Document:

EX-10.8

 Exhibit 10.8 

BIDMC Agreement No: A9456 
 BIDMC
Case No: 1952 
 BETH ISRAEL DEACONESS MEDICAL CENTER 

EXCLUSIVE LICENSE AGREEMENT 

This License Agreement (“Agreement”) is made as of the date immediately above the signatures of the Parties below
(“Effective Date”) between Beth Israel Deaconess Medical Center, a not-for-profit Massachusetts corporation, with a principal place of operation
at 330 Brookline Avenue, Boston, Massachusetts 02215 (“BIDMC”), and X4 Pharmaceuticals, Inc. a corporation, having a principal place of business at 784 Massachusetts Avenue, Suite 140, Cambridge MA 02139
(“Licensee”), each referred to individually as a “Party” and collectively as the “Parties”. 

RECITALS 
 BIDMC, as a
center for patient care, research and education, owns certain Patent Rights (defined below) through assignment and desires to benefit the public by disseminating the results of its research through the grant of a license of those Patent Rights to
Licensee for the commercial development, manufacture, distribution and use of Products and Processes (defined below). 
 Licensee has the
capability to commercially develop, manufacture, distribute and use Products and Processes for public use and benefit and desires to receive a license to such Patent Rights. 

For good and valuable consideration, the sufficiency of which the Parties acknowledge, the Parties agree as follows: 

1. DEFINITIONS 
 The
following terms have the following meanings: 
 1.1    “Affiliate” with respect to either Party, means
any corporation or other legal entity other than that Party, in whatever country organized, that directly or indirectly controls, is controlled by or is under common control with that Party. For the purposes of this definition, the term
“control” means (a) for Licensee, (i) beneficial ownership of at least fifty percent (50%) of the voting securities of a corporation or other business organization with voting securities or (ii) a fifty percent (50%) or
greater interest in the net assets or profits of a partnership or other business organization without voting securities; and (b) for BIDMC, the power, direct or indirect, to elect or appoint fifty percent (50%) or more of the directors or
trustees, or to cause direction of management and policies, whether through the ownership of voting securities, by contract or otherwise. 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 1.2    “Claim” means any pending or issued claim of any
Patent Right that has not been permanently revoked, nor held unenforceable or invalid by a decision of a court or other governmental agency of competent jurisdiction that is unappealable or unappealed in the time allowed for appeal. 

1.3    “Distributor” means any entity to whom Licensee, a Licensee Affiliate or a Sublicensee has granted,
express or implied, the right to Sell and/or distribute any Product or Process on behalf of Licensee, such Licensee Affiliate or such Sublicensee, without granting such entity the right to make, have made, use or have used. A Distributor shall not
be considered a Sublicensee under this Agreement. 
 1.4    “Field” means all fields of use. 

1.5    “Patent Costs” means all costs and expenses of any kind, including attorneys’ fees, associated
with the preparation, filing, prosecution and maintenance of all Patent Rights. 
 1.6    “Patent
Challenge” means a challenge in a legal or administrative proceeding to the validity, patentability or enforceability of any of the Patent Rights or otherwise opposing in a legal or administrative proceeding any of the Patent Rights. 

1.7    “Patent Rights” means the United States and international patents, patent applications and
provisional applications listed on Appendix A, and the patents resulting from any of the foregoing applications; and any divisions, continuations, and
continuations-in-part (but only to the extent the claims are directed to subject matter specifically described in the patent applications listed in Appendix A),
including foreign patent applications or patents that are equivalent to the foregoing; and any reissues, reexaminations or extensions of any of the foregoing; and any and all patents and patent applications claiming priority benefit from or to any
of the foregoing, and all patents and patent applications from which any of the foregoing claim priority benefit from or to. 

1.8    “Process” means any process, method or service the use or performance of which, in whole or in
part, is (a) covered by any Claim in the Patent Rights; or (b) which, absent the license granted hereunder, would infringe one or more Claims of the Patent Rights. 

1.9    “Product” means 

(a)    any product (including any apparatus or kit) that in whole or through a component part thereof, the manufacture,
use, practice or Sale of which is covered by one or more Claims of the Patent Rights or, in the absence of a license from BIDMC, would infringe one or more Claims of the Patent Rights; or 

(b)    any product (including any apparatus or kit) that is developed, produced or manufactured with, or used pursuant to,
a Process as defined in Section 1.9. 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 1.10    “Related Information” means any research data,
designs, formulae, process information and other information pertaining to any invention claimed in the Patent Rights owned by BIDMC, for which there is no obligation to any third party, and (i) is known as of the Effective Date and disclosed
to the BIDMC Technology Ventures Office by Dr. Mier; and (ii) is in addition to the disclosures in the patent application for the Patent Rights. Licensee shall maintain all such Related Information as the Confidential Information of BIDMC.

 1.11    “Sale” (and “Sell” and “Sold” as the case may be) shall mean to sell or
have sold, to lease or have leased, to import or have imported or otherwise to transfer or have transferred a Product or Process for consideration (in the form of cash or otherwise), and further in the case of a Process to use or perform such
Process in exchange for consideration for the benefit of a third party. 
 1.12    “Sublicensee” means
any sublicensee of the rights granted to Licensee pursuant to Section 2.1(a). Sublicensee shall not include Distributors. 

1.13    “Term” means the term of this Agreement, which shall commence on the Effective Date and shall
remain in effect until the date on which all issued patents and filed patent applications within the Patent Rights have expired or been permanently abandoned, unless this Agreement is terminated earlier as provided herein. 

1.14    “Territory” means worldwide. 

2. LICENSE 

2.1    Grant of License. 

(a)    Subject to the terms of this Agreement and BIDMC’s rights in the Patent Rights, BIDMC hereby grants to Licensee
and its Affiliates in the Field in the Territory for the Term, an exclusive, royalty-free, fully paid-up (upon payment of the License Issue Fee pursuant to Section 3.1) license under BIDMC’s rights
in the Patent Rights to make, have made, use, have used, Sell and have Sold Products and Processes. 
 (b)    Subject to
the terms of this Agreement and specifically Section 2.2, BIDMC grants Licensee the right to grant sublicenses under the rights granted in Section 2.1(a) and Section 2.1(c), provided that in each case Licensee shall be responsible for
the performance of any obligations of Sublicensees relevant to this Agreement as if such performance were carried out by Licensee itself, which right to grant sublicenses will be exclusive with respect to the rights granted in Section 2.1(a)
and will be non-exclusive with respect to the rights granted in Section 2.1(c). 

(c)    Subject to the terms of this Agreement, BIDMC hereby grants to Licensee and its Affiliates (subject to
Section 2.1(e)) in the Field in the Territory for the 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 
Term, a nonexclusive royalty-free, fully paid-up (upon payment of the License Issue Fee pursuant to Section 3.1) right to use Related Information
disclosed by BIDMC to Licensee to develop, make, have made, use, have used, Sell and have Sold and otherwise commercialize the Products and Processes. 

(d)    The licenses granted in Sections 2.1(a) and 2.1(c) above include: 

 

	 	(i)	 the right to grant to the purchaser, user or consumer of Products the right to use such purchased Products in a
method coming within the scope of Patent Rights, and such purchasers, users and consumers will not be considered Sublicensees hereunder; and 

  

	 	(ii)	 the right to grant a Distributor the right to Sell (but not to make, have made, use or have used) such Products
and/or Processes for or on behalf of Licensee, Licensee Affiliates and Sublicensees in a manner consistent with this Agreement. 

(e)    The foregoing license grants to Licensee Affiliates are subject to each such 

Affiliate assuming the same obligations as those of Licensee and becoming subject to the same terms and conditions under this Agreement; and
further provided that Licensee shall be responsible for the performance of all of such obligations and for compliance with all of such terms and conditions by Affiliate. 

2.2    Sublicenses. Each sublicense granted hereunder shall be consistent with and comply with all terms of this
Agreement, and shall incorporate terms and conditions sufficient to enable Licensee to comply with this Agreement. Licensee shall provide to BIDMC a fully signed copy of all sublicense agreements and amendments thereto, including all exhibits,
attachments and related documents, within [***] of executing the same, excluding sublicenses granted to third parties that are clinical research organizations, contract manufacturers, contract laboratory organizations, and other similar third
parties that support the development and commercialization of Products and/or Processes on a fee-for-service basis as Sublicensees hereunder (“Third Party
Contractors”). Licensee will be permitted to redact from such fully signed copies proprietary and other sensitive information to the extent that such redaction does not impact BIDMC’s ability to confirm Licensee’s compliance with this
Agreement. Notwithstanding the foregoing, Licensee will disclose to BIDMC the identity of the Sublicensee (excluding, for avoidance of doubt, Third Party Contractors). Any sublicense which is not in accordance with the forgoing provisions shall be
null and void. Any Sublicensee and Distributor agreement under this Agreement shall provide for termination of any sublicense granted hereunder upon termination of this Agreement for any reason. Upon termination of this Agreement for any reason, any
Sublicensee and Distributor not then in default under its agreement shall have the right to seek a license from BIDMC. BIDMC agrees to negotiate such licenses in good faith under reasonable terms and conditions consistent with this Agreement. 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 Upon Licensee’s request during the term of this Agreement, BIDMC agrees to provide, on
a timely basis, a letter to an existing or potential Sublicensee specifically named by Licensee stating that, in the event of termination of this Agreement, BIDMC will grant a license to Sublicensee under terms and conditions to be no less favorable
as a whole than those granted to Sublicensee by Licensee, provided that Sublicensee is not in default of its sublicense agreement with Licensee at the time such license is to be granted by BIDMC and provided that BIDMC shall not assume any
obligation of Licensee to Sublicensee under such agreement, except for the license granted. Licensee’s right to request and Sublicensee’s right to acquire such letter are specifically conditioned on BIDMC’s review of the final,
executed sublicense agreement between Sublicensee and Licensee and on BIDMC’s conclusion, at its reasonable discretion, that such sublicense agreement is reasonable and in the best interests of the commercialization of the Patent Rights. 

2.3    Retained Rights; Requirements. Any and all licenses granted hereunder are subject to: 

(a)    the royalty-free right of BIDMC and BIDMC’s Affiliates and of academic, government and not-for-profit institutions to make, use and/or practice the technology or method described and/or claimed in the Patent Rights solely for
non-commercial research purposes; and 
 (b)    for Patent Rights supported by
federal funding, the rights, conditions and limitations imposed by U.S. law (see 35 U.S.C. § 202 et seq. and regulations pertaining thereto), including without limitation: 

 

	 	(i)	 the royalty-free non-exclusive license granted to the U.S. government;
and 

  

	 	(ii)	 to the extent required by the National Institutes of Health (as the federal funding agency), the requirement
that any Products (if they qualify as “subject inventions” under 35 U.S.C. § 204) used or sold in the United States shall be manufactured substantially in the United States. 

If Licensee or any of its Affiliates or Sublicensees wishes to obtain a waiver of the requirement under Section 2.3(b)(ii), BIDMC agrees
to reasonably cooperate with Licensee or such Affiliates or Sublicensees in obtaining such waiver, including by directly filing for such waiver if required by applicable law and regulations. 

2.4    No Additional Rights. Nothing in this Agreement shall be construed to grant Licensee an express or implied
license under any patent, technology or intellectual property right owned solely or jointly by BIDMC, other than the Patent Rights and Related Information expressly licensed hereunder. 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 3. PAYMENTS 

3.1    License Issue Fee. Licensee shall pay BIDMC a non-refundable, non-creditable license issue fee in the sum of twenty thousand dollars ($20,000) (“License Issue Fee”) within twenty (20) business days of the Effective Date of this Agreement. For avoidance of doubt,
upon payment of the License Issue Fee, the licenses and rights granted to Licensee under Section 2.1 shall be fully paid-up and royalty-free. 

3.2    Form of Payment. All payments due under this Agreement shall be drawn on a United States bank and shall be
payable in United States dollars. Each payment shall reference this Agreement and identify the obligation under this Agreement that the payment satisfies. Conversion of foreign currency to U.S. dollars shall be made at the conversion rate existing
in the United States, as reported in The Wall Street Journal, on the last working day of the applicable Reporting Period. Such payments shall be without deduction of exchange, collection or other charges, and, specifically, without deduction of
withholding or similar taxes or other government imposed fees or taxes. Checks for all payments due to BIDMC under this Agreement shall be made payable to BIDMC and addressed as set forth in Section 12.2. Payments via wire transfer should be
made as follows: 
 [***] 

3.3    Overdue Payments. The payments due under this Agreement shall, if overdue, bear interest at two percentage
Points above the Prime Rate of interest as reported in the Wall Street Journal on the date payment is due until payment thereof, not to exceed the maximum permitted by law. Any such overdue payments when made shall be accompanied by all interest so
accrued. Payment and acceptance, in whole or in part, of interest and the overdue payment shall not preclude BIDMC from exercising any other rights it may have as a consequence of the lateness of any payment. 

3.4    Consequences of a Patent Challenge. In the event that (i) Licensee, any of its Affiliates, or any
Sublicensee brings a Patent Challenge against BIDMC, or (ii) Licensee, any of its Affiliates, or any Sublicensee assists another party in bringing a Patent Challenge against BIDMC (except as required under a court order or subpoena), and
(iii) BIDMC does not choose to exercise its rights to terminate this Agreement pursuant to Section 9.4, then if such a Patent Challenge is successful, Licensee will have no right to recoup any monies paid during the period of challenge.

 4. PATENT PROSECUTION AND MAINTENANCE 

4.1    Prosecution. Provided that Licensee seeks and maintains the strongest and broadest patent claims reasonably
practicable and uses patent attorneys acceptable to BIDMC, such acceptance not to be unreasonably withheld, BIDMC appoints Licensee as its exclusive agent to prepare, file, prosecute (including to seek extensions of), maintain and defend (including
inter partes and opposition proceedings) all of the Patent Rights 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 
during the Term. Licensee shall copy BIDMC on all patent prosecution documents and give BIDMC reasonable opportunities to advise Licensee on such filing, prosecution, maintenance and defense.
BIDMC shall reasonably cooperate with Licensee in the filing, prosecution, maintenance and defense of the Patent Rights. Such cooperation includes promptly executing all documents, or requiring inventors, subcontractors, employees and consultants
and agents of BIDMC and its Affiliates to execute all documents, and joining as a party in any proceedings, as reasonable and appropriate so as to enable the filing, prosecution, maintenance and defense of any Patent Right in any country. In the
event Licensee desires to abandon the prosecution, maintenance or defense of any patent, patent application, or any Claims within the Patent Rights where such Claims are not included in a continuation, divisional or other patent or patent
application, Licensee shall provide BIDMC with [***] prior written notice of such intended abandonment or decline of responsibility and, as to Claims, shall reasonably consider BIDMC’s judgment in whether or not to abandon or not defend such
Claim, and, as to such patent or patent application, such abandonment or election not to defend shall only be with prior notice to BIDMC on a patent by patent and country by country basis. If BIDMC desires to prosecute, maintain or defend any such
Patent Rights proposed to be abandoned by Licensee under this Agreement, the right to prepare, file, prosecute, maintain and defend the relevant Patent Rights shall revert, as between Licensor and Licensee, to BIDMC, at BIDMC’s expense, subject
to any third party rights. In such event, such BIDMC paid-for rights shall be removed from the definition of Patent Rights under this Agreement, the licenses granted to Licensee and its Affiliates as to such
Patent Rights shall terminate, and BIDMC shall have the right to abandon or maintain and license such Patent Rights in its discretion. 

4.2    Confidentiality of Prosecution and Maintenance Information. Each Party agrees to treat all information
related to prosecution and maintenance of Patent Rights as Confidential Information in accordance with the provisions of Appendix B. 
 5.
REPORTS 
 5.1    Progress Reports. Within [***] after the end of each calendar year, Licensee shall report
in writing to BIDMC on progress during such preceding [***] period in developing and/or commercializing Products and/or Processes, including, without limitation, progress on research and development, status of applications for regulatory approvals,
manufacturing, sales, sublicensing and the number of sublicenses (excluding Third Party Contractors) entered into and marketing. 
 6.
THIRD PARTY INFRINGEMENT AND LEGAL ACTIONS 
 6.1    Licensee Right to Prosecute. Licensee shall have the
first right, but not the obligation, to initiate legal proceedings to protect the Patent Rights from infringement, with respect to a Claim of a Patent Right in the Field in the Territory, and prosecute infringers at Licensee’s expense. Before
commencing such action, Licensee and, as applicable, any Affiliate, shall consult with BIDMC, concerning the advisability of bringing suit, the selection of counsel and the jurisdiction for such action (provided

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 
Licensee must have BIDMC’s prior written consent (not to be unreasonably withheld) with respect to selection of jurisdiction for any action in which BIDMC may be joined as a party-plaintiff)
and shall use reasonable efforts to accommodate the views of BIDMC regarding the proposed action, especially but without limitation with respect to potential effects on the public interest. Licensee shall be responsible to BIDMC for all costs,
expenses and liabilities arising out or and in connection with any such action and shall indemnify and hold BIDMC harmless therefrom, regardless of whether BIDMC is a party-plaintiff, except for the expense of any independent counsel retained by
BIDMC in accordance with Section 6.2 below. Licensee shall keep BIDMC informed of the progress of such proceedings and shall make its counsel reasonably available to BIDMC for discussion of such proceedings. BIDMC shall also be entitled to
independent counsel in such proceedings but at its own expense, said expense to be offset against any damages received by the Licensee bringing suit in accordance with Section 6.4 

6.2    BIDMC Right to Prosecute and/or Join as a Party-Plaintiff. 

(a)    In the event that Licensee elects not to take action pursuant to this Section 6.1, Licensee shall so notify
BIDMC promptly in writing of its intention in good time to enable BIDMC to meet any deadlines by which an action must be taken to establish or preserve any enforcement rights and BIDMC shall have the right to take steps to protect the Patent Rights
from infringement, with respect to a Claim of a Patent Right in the Field in the Territory, and prosecute infringers at BIDMC’s expense and subject to any third party rights. If BIDMC notifies Licensee that it intends to so prosecute, subject
to any third party rights, BIDMC shall use reasonable efforts, within [***] of its notice to Licensee, to (i) cause such infringement to terminate; (ii) reach a settlement with infringers; or (iii) initiate legal proceedings against
the infringer. Nothing in this Section 6.2 shall be construed to prevent Licensee from initiating legal proceedings, in accordance with its independent judgement of the merits of an infringement action, as provided in Section 6.1. 

(b)    If Licensee elects to commence an action as described in Section 6.1 above, BIDMC shall have, in its sole
discretion and at its own expense, the option to voluntarily join such action as a party-plaintiff. If required by law for the purposes of Licensee bringing an action against an alleged infringer, BIDMC agrees that it shall allow Licensee to join
BIDMC in such action as a party-plaintiff 
 6.3    Notice of Actions; Settlement. Licensee shall promptly inform
BIDMC of any action or suit relating to Patent Rights and shall not enter into any settlement, consent judgment or other voluntary final disposition of any action relating to Patent Rights, including but not limited to appeals, that would adversely
affect the validity, patentability or enforceability of the Patent Rights without the prior written consent of BIDMC, which shall not be unreasonably withheld or delayed. 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 6.4    Recovery. Subject to any third party rights, any award
paid by third parties as the result of such proceedings (whether by way of settlement or otherwise) shall first be applied to reimbursement of any legal fees and expenses incurred by both Parties, in proportion to their expenditures, and then the
remainder, if any, shall be distributed between the Parties as follows: 
 (a)    Licensee shall receive an amount equal
to its lost profits or a reasonable royalty on the infringing sales, or whichever measure of damages the court shall have applied; and 

(b)    the balance, if any, remaining after Licensee and BIDMC have been compensated under Section 6.4(a) shall be
shared equally by the Parties. 
 7. INDEMNIFICATION AND INSURANCE 

7.1    Indemnification. 

(a)    Licensee shall indemnify, defend and hold harmless BIDMC and its Affiliates and their respective trustees,
directors, officers, medical and professional staff, employees, and agents and their respective successors, heirs and assigns (the “Indemnitees”), against any liability, damage, loss or expense (including reasonable attorney’s fees
and expenses of litigation) incurred by or imposed upon the Indemnitees or any one of them in connection with any claims, suits, actions, demands or judgments commenced or obtained by a third party arising out of any theory of liability, including
without limitation, any theory of product liability (including, but not limited to, actions in the form of contract, tort, warranty, or strict liability) concerning any Product or Process made, used or sold pursuant to any right or license granted
under this Agreement. BIDMC shall promptly provide written notice to Licensee of any claim to which indemnification applies under this Section 7.1(a). 

(b)    Licensee agrees, at its own expense, to, defend against and resolve, and will have the right to assume and control
the defense and resolution of, any actions or claims brought or filed against any party indemnified hereunder with respect to the subject of indemnity contained herein, whether or not such actions are rightfully brought; provided, however, that any
Indemnitee shall have the right to retain its own counsel, at the expense of Licensee, if representation of such Indemnitee by counsel retained by Licensee would be inappropriate because of actual or potential conflicts of interests of such
Indemnitee and any other party represented by such counsel. Licensee agrees to keep BIDMC informed of the progress in the defense and disposition of such claim and to consult with BIDMC prior to any proposed settlement. The party indemnified
hereunder will reasonably cooperate with Licensee at Licensee’s expense and will make available to Licensee relevant information under the control of such indemnified party. 

(b)    This Section 7.1 shall survive expiration or termination of this Agreement. 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 7.2    Insurance. 

(a)    Beginning at such time as any Product or Process licensed under this Agreement is being commercially distributed,
sold, leased or otherwise transferred, or performed or used (other than for the purpose of obtaining regulatory approvals), by Licensee, Licensee shall, at its sole cost and expense, procure and maintain commercial general liability insurance in
amounts not less than $[***] per incident and $[***] annual aggregate and naming the Indemnitees as additional insureds. Such commercial general liability insurance shall provide (i) product liability coverage and (ii) broad form
contractual liability coverage for the indemnification obligations under Section 7.1 of this Agreement. If Licensee or its Affiliates or Sublicensees elects to self-insure all or part of the limits described above (including deductibles or
retentions which are in excess of $[***] annual aggregate), such self-insurance program must be reasonably acceptable to the Licensor, provided that if a Sublicensee elects to self-insure and such Sublicensee has a market capitalization of at least
[***] dollars ($[***]), then such Sublicensee’s self-insurance program shall automatically be deemed reasonably acceptable to Licensor and not subject to Licensor’s review. The minimum amounts of insurance coverage required under this
Section 7.2 shall not be construed to create a limit of liability with respect to the indemnification obligations under Section 7.1 of this Agreement. 

(b)    Licensee shall provide BIDMC with written evidence of such insurance upon request of BIDMC. Licensee shall provide
BIDMC with written notice at least [***] prior to the cancellation, non-renewal or material change in such insurance; if Licensee does not obtain replacement insurance providing comparable coverage prior to
the expiration of such [***] period, BIDMC shall have the right to terminate this Agreement pursuant to Section 9.3 (and subject to the cure right therein). 

(c)    Licensee shall maintain such commercial general liability insurance beyond the expiration or termination of this
Agreement during (i) the period that any such Product or Process, is being commercially distributed, sold, leased or otherwise transferred, or performed or used (other than for the purpose of obtaining regulatory approvals), by Licensee or by a
licensee, affiliate or agent of Licensee and (ii) a reasonable period after the period referred to in (c) (i) above which in no event shall be less than [***]. 

(d)    This Section 7.2 shall survive expiration of termination of this Agreement. 

7.3    Affiliates and Sublicensees. Licensee shall require all its Affiliates and Sublicensees (other than Third
Party Contractors) to comply with the provisions and obligations under this Section 7 as if such entity were the Licensee. 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 8. REPRESENTATION; DISCLAIMER OF WARRANTIES; LIMITATION OF LIABILITY 

8.1    Representation. To the best knowledge of BIDMC’s Technology Ventures Office, BIDMC represents that:

 (a)    No approval, authorization, consent or other order or action of or filing with any court, administrative agency
or other governmental authority is required for the execution and delivery by it of this Agreement or the consummation by it of the transactions contemplated hereby; 

(b)    it has full right and authority to enter into this Agreement and to grant the licenses and other rights to Licensee
as herein described; 
 (c)    the execution, delivery and performance of this Agreement does not conflict with any other
agreement, contract, instrument or understanding, oral or written, to which BIDMC is a party, or by which it is bound; and 

(d)    none of BIDMC nor any of its Affiliates has entered into any agreement or otherwise licensed, granted, assigned,
transferred, conveyed or otherwise encumbered or disposed of any right, title or interest in or to any of the Patent Rights that would conflict with or impair the scope of any rights or licenses granted hereunder. 

8.2    No Warranties. BIDMC HEREBY DISCLAIMS AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND, EXPRESS OR
IMPLIED, CONCERNING THE PATENT RIGHTS AND ANY OF THE RIGHTS GRANTED HEREUNDER, INCLUDING, WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NONINFRINGEMENT, VALIDITY OF PATENT RIGHTS CLAIMS, WHETHER ISSUED OR
PENDING, AND THE ABSENCE OF LATENT OR OTHER DEFECTS, WHETHER OR NOT DISCOVERABLE. SPECIFICALLY, AND NOT TO LIMIT THE FOREGOING, BIDMC MAKES NO WARRANTY OR REPRESENTATION (i) REGARDING THE VALIDITY OR SCOPE OF ANY OF THE CLAIM(S), WHETHER ISSUED
OR PENDING, OF ANY OF THE PATENT RIGHTS, AND (ii) THAT THE EXPLOITATION OF THE PATENT RIGHTS OR ANY PRODUCT OR PROCESS WILL NOT INFRINGE ANY PATENTS OR OTHER INTELLECTUAL PROPERTY RIGHTS OF BIDMC OR OF ANY THIRD PARTY. 

8.3    Limitation of Liability. IN NO EVENT SHALL BIDMC OR ANY OF ITS AFFILIATES OR ANY OF THEIR RESPECTIVE
TRUSTEES, DIRECTORS, OFFICERS, MEDICAL AND PROFESSIONAL STAFF, EMPLOYEES AND AGENTS BE LIABLE TO LICENSEE OR ANY OF ITS AFFILIATES, SUBLICENSEES OR DISTRIBUTORS FOR INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND ARISING IN ANY
WAY OUT OF THIS AGREEMENT 

  
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Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 
OR THE LICENSE RIGHTS GRANTED HEREUNDER, HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, INCLUDING WITHOUT LIMITATION ECONOMIC DAMAGES OR INJURY TO PROPERTY OR LOST PROFITS, REGARDLESS OF WHETHER
BIDMC SHALL BE ADVISED, SHALL HAVE OTHER REASON TO KNOW, OR IN FACT SHALL KNOW OF THE POSSIBILITY OF THE FOREGOING. 
 9. TERMINATION

 9.1    Termination for Failure to Pay. If Licensee fails to make any payment due hereunder, BIDMC shall
have the right to terminate this Agreement upon fifteen (15) business days written notice, unless Licensee makes such payments plus any interest due, as set forth in Section 3.3, within said fifteen (15) day notice period. If payments
are not made, BIDMC may immediately terminate this Agreement at the end of said fifteen (15) business day period. 

9.2    Termination for Insolvency. BIDMC may terminate this Agreement immediately upon written notice with no
further notice obligation or opportunity to cure if Licensee shall become insolvent, shall make an assignment for the benefit of creditors, or shall have a petition in bankruptcy filed for or against it that is not dismissed within sixty
(60) days of filing. 
 9.3    Termination for Non-Financial Default.
If Licensee or any of its Affiliates shall materially default in the performance of any of its material obligations under this Agreement (including any such obligations undertaken by Sublicensees) (excluding as provided for in Sections 9.1 and 9.2)
and if such material default has not been cured within sixty (60) days after notice by BIDMC in writing of such material default, then at the end of such cure period, BIDMC may, at its option, in its sole discretion, either (i) immediately
terminate any licenses granted hereunder with respect to the country or countries in which such material default has occurred, or (ii) terminate the Agreement in its entirety. BIDMC shall have the foregoing termination rights immediately, upon
written notice, if any such same material default occurs more than three times, even if cured within such sixty (60) day periods. 

9.4    Patent Challenge. During the Term, if a Sublicensee (excluding a Third Party Contractor) brings a Patent
Challenge or assists another party in bringing a Patent Challenge (except as required under a court order or subpoena or except as raised as a defense against a claim, action or proceeding asserted by BIDMC or its Affiliates against such
Sublicensee), then BIDMC may send a written demand to Licensee to terminate such sublicense. If Licensee fails to so terminate such sublicense within sixty (60) days after BIDMC’ s demand, BIDMC may immediately terminate this Agreement
and/or any licenses granted hereunder. 
 9.5    Termination by Licensee. Licensee shall have the right to
terminate this Agreement for any reason by giving ninety (90) days advance written notice to BIDMC. 

  
 12 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 9.6    Effects of Termination of Agreement. 

(a)    General. Upon termination of this Agreement or any of the licenses hereunder for any reason, final reports in
accordance with Section 5.1 shall be submitted to BIDMC and all payments, including without limitation any unreimbursed Patent Costs, accrued or due to BIDMC as of the termination date shall become immediately payable. The termination or
expiration of this Agreement or any licenses granted hereunder shall not relieve any Party or its Affiliates of obligations arising before such termination or expiration. For the avoidance of doubt, termination of this Agreement shall not affect the
right of Licensee, its Affiliates, Sublicensees and Distributors to continue operating under Licensee’s rights as joint owner and co-applicant of the Patent Rights. 

(b)    Survival. The following provisions shall survive the expiration or termination of this Agreement: Sections 1,
2.2 (last two sentences of the first paragraph), 3, 7, 8, 11 and 9.6 and Appendix B. 
 10. COMPLIANCE WITH LAW 

10.1    Compliance. Licensee shall have the sole responsibility for compliance with all government statutes and
regulations that relate to Products and Processes, including, but not limited to, those of the Food and Drug Administration and the Export Administration, and any applicable laws and regulations of any other country in the Territory. Licensee agrees
that it shall be solely responsible for obtaining any necessary licenses to export, re¬export, or import Products or Processes covered by Patent Rights and/or Confidential Information and that it will indemnify, defend, and hold BIDMC harmless
(in accordance with Section 8.1) for the consequences of any violation by Licensee, its Affiliates, Sublicensees or Distributors of any such laws or regulations. 

10.2    Patent Numbers. Licensee shall cause all Products sold in the United States to be marked with all applicable
U.S. Patent Numbers, to the full extent required by United States law. Licensee shall similarly cause all Products shipped to or sold in any other country to be marked in such a manner as to conform with the patent laws and practices of such
country. 
 11. ASSIGNMENT 

11.1    Assignment. This Agreement is personal to Licensee and no rights or obligations may be assigned by Licensee
without the prior written consent of BIDMC, except that Licensee may assign its rights and obligations under this Agreement to an Affiliate or to a successor in connection with the merger, consolidation, or sale of all or substantially all of its
assets or equity or that portion of its business to which this Agreement relates (“Assignment”); provided, however, that Licensee shall provide notification to BIDMC within [***] of such Assignment 

  
 13 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 12. MISCELLANEOUS 

12.1    Entire Agreement. This Agreement and the Sponsored Research Agreement (BIDMC Agreement No. A8755) and its
Amendment No. 1 (BIDMC Agreement No. A8755) between the Parties, dated January 1, 2015 and February 2, 2016 respectively with continuing obligations, non-disclosure agreement constitutes the
entire understanding between the Parties with respect to the subject matter hereof. 
 12.2    Notices. Any
notice, communication or payment required or permitted to be given or made hereunder shall be in writing and, except as otherwise expressly provided in this Agreement, shall be deemed given or made and effective (i) when delivered personally;
or (ii) when delivered by telex or telecopy (if not a payment); or (iii) when received if sent by overnight express or mailed by certified, registered or regular mail, postage prepaid, addressed to parties at their address stated below, or
to such other address as such party may designate by written notice in accordance with the provisions of this Section 10.2. 
  

	BIDMC:	 Attn: [***] 

Beth Israel Deaconess Medical Center 

330 Brookline Avenue, BR2 

Boston, MA 02215 

Phone: 617 667-9490 

Fax: 617-667-4445 

Email: [***] 
  

	With a copy to:	 General Counsel 

Legal Department 

Beth Israel Deaconess Medical Center 

330 Brookline Avenue, Suite 300 

Boston, MA 02215 
  

	LICENSEE:	 Attn: John Celebi 

Chief Operating Officer 

X4 Pharmaceuticals, Inc. 

784 Massachusetts Avenue, Suite 140 

Cambridge MA 02139 

12.3    Amendment; Waiver. This Agreement may be amended and any of its terms or conditions may be waived only by a
written instrument executed by an authorized signatory of the Parties or, in the case of a waiver, by the Party waiving compliance. The failure of either Party at any time or rimes to require performance of any provision hereof shall in no manner
affect its rights at a later time to enforce the same. No waiver by either Party of any condition or term shall be deemed as a further or continuing waiver of such condition or term or of any other condition or term. 

  
 14 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 12.4    Binding Effect. This Agreement shall be binding upon and
inure to the benefit of and be enforceable by the Parties hereto and their respective permitted successors and assigns. 

12.5    Force Majeure. Neither Party shall be responsible for delays resulting from fire, explosion, flood, war,
sabotage, strike or riot, or similar causes beyond the reasonable control of such Party, provided that the nonperforming Party uses commercially reasonable efforts to avoid or remove such causes of nonperformance and continues performance under this
Agreement with reasonable dispatch whenever such causes are removed. 
 12.6    Use of Name. Neither Party shall
use the name of the other Party or of any trustee, director, officer, staff member, employee, student or agent of the other Party or any adaptation thereof in any advertising, promotional or sales literature, publicity or in any document employed to
obtain funds or financing without the prior written approval of the Party or individual whose name is to be used. 

12.7    Governing Law. This Agreement shall be governed by and construed and interpreted in accordance with the laws
of the Commonwealth of Massachusetts, excluding with respect to conflict of laws, except that questions affecting the construction and effect of any patent shall be determined by the law of the country in which the patent shall have been granted.
Each Party agrees to submit to the exclusive jurisdiction of the Superior Court for Suffolk County, Massachusetts, and the United States District Court for the District of Massachusetts with respect to any claim, suit or action in law or equity
arising in any way out of this Agreement or the subject matter hereof. 
 12.8    BIDMC Policies. Licensee
acknowledges that BIDMC’s employees and medical and professional staff members and the employees and staff members of BIDMC’s Affiliates are subject to the applicable policies of BIDMC and such Affiliates, including, without limitation,
policies regarding conflicts of interest, intellectual property and other matters. Licensee shall provide BIDMC with any agreement it proposes to enter into with any employee or staff member of BIDMC or any of BIDMC’s Affiliates for
BIDMC’s prior review and shall not enter into any oral or written agreement with such employee or staff member which it knows conflicts with any such policy. BIDMC shall provide Licensee, at Licensee’s request, with copies of any such
policies applicable to any such employee or staff member. 
 12.9    Severability. If any provision(s) of this
Agreement are or become invalid, are ruled illegal by any court of competent jurisdiction or are deemed unenforceable under then current applicable law from time to time in effect during the term hereof; it is the intention of the parties that the
remainder of this agreement shall not be effected thereby. It is further the intention of the parties that in lieu of each such provision which is invalid, illegal or unenforceable, there be substituted or added as part of this Agreement a provision
which shall be as similar as possible in economic and business objectives as intended by the parties to such invalid, illegal or enforceable provision, but shall be valid, legal and enforceable. 

  
 15 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 12.10    Interpretation. The parties hereto are sophisticated,
have had the opportunity to consult legal counsel with respect to this transaction and hereby waive any presumptions of any statutory or common law rule relating to the interpretation of contracts against the drafter. 

12.11    Headings. All headings are for convenience only and shall not affect the meaning of any provision of this
Agreement. 
 [Remainder of page intentionally left blank] 

  
 16 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed by their duly
authorized representatives as of the date first written above. 
 The Effective Date of this License Agreement is December 23,
2016. 
  

													
	X4 PHARMACEUTICALS, INC.	 	BETH ISRAEL DEACONESS MEDICAL CENTER
					
	BY:	 	/s/ John Celebi	 		 	BY:	 	/s/ Vikas Sukhatme, M.D., Sc. D.
		 	  Name:	 	John Celebi	 		 		 	  Name:	 	Vikas Sukhatme, M.D., Sc. D.
					
	TITLE:	 	Chief Operating Officer	 		 	TITLE:	 	Chief Academic Officer
					
	DATE:	 	12/29/2016	 		 	DATE:	 	12/27/2016

  
 17 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 Appendix A 

[***] 

  
 18 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 Appendix B 

CONFIDENTIALITY TERMS AND CONDITIONS 

1.    Definition of Confidential Information. “Confidential Information” shall mean any information,
including but not limited to data, techniques, protocols or results, or business, financial, commercial or technical information, disclosed by one Party (each a “Discloser” as applicable) to the other Party (each a “Recipient” as
applicable) in connection with the terms of that certain Exclusive License Agreement dated December , 2016 (the “License Agreement”) and identified as confidential at the time of disclosure. Capitalized terms used in this Appendix that are
not otherwise defined herein have the meanings ascribed in the License Agreement to which this Appendix is attached and made a part thereof. 

2.    Exclusions. “Confidential Information” under this Agreement shall not include any information that
(i) is or becomes publicly available through no wrongful act of Recipient; (ii) was known by Recipient prior to disclosure by Discloser, as evidenced by tangible records; (iii) becomes known to Recipient after disclosure from a third
party having an apparent bona fide right to disclose it without any confidentiality obligation; (iv) is independently developed or discovered by Recipient without use of Discloser’s Confidential Information, as evidenced by tangible
records; or (v) is disclosed to another party by Discloser without restriction on further disclosure. The obligations of confidentiality and non-use set forth in this Agreement shall not apply with
respect to any information that Recipient is required to disclose or produce pursuant to applicable law, court order or other valid legal process provided that Recipient promptly notifies Discloser prior to such required disclosure, discloses such
information only to the extent so required and cooperates reasonably with Discloser’s efforts to contest or limit the scope of such disclosure. 

3.    Permitted Purpose. Recipient shall have the right to, and agrees that it will, use Discloser’s
Confidential Information solely for the performance of its obligations and exercise of its rights under the License Agreement (the “Purpose”), except as may be otherwise specified in a separate definitive written agreement negotiated and
executed between the parties. 
 4.    Restrictions. For the term of the License Agreement and a period of [***]
thereafter (and indefinitely with respect to any individually identifiable health information disclosed by BIDMC to Licensee, if any), each Recipient agrees that: (i) it will not use such Confidential Information for any purpose other than as
specified herein; and (ii) it will use reasonable efforts (but no less than the efforts used to protect its own confidential and/or proprietary information of a similar nature) not to disclose such Confidential Information to any other person
or entity except as expressly permitted hereunder or the License Agreement. Recipient may, however, disclose Discloser’s Confidential Information only on a
need-to-know basis to its and its Affiliates employees, staff members and agents (“Receiving Individuals”) who are directly participating in the Purpose and
who are informed of the confidential nature of such information, provided Recipient shall be responsible for compliance by Receiving Individuals with the terms of this Agreement and any breach thereof Each party further agrees not to use the name of
the other party or any of its Affiliates or any of their respective trustees, directors, officers, staff members, 

  
 19 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended. 

 
employees, students or agents in any advertising, promotional or sales literature, publicity or in any document employed to obtain funds or financing without the prior written approval of the
party or individual whose name is to be used, in the case of BIDMC such approval to be given by the Public Affairs Department. This Section 4 shall survive termination or expiration of this Agreement. 

5.    Right to Disclose. Discloser represents that to the best of its knowledge it has the right to disclose to each
Recipient all of Discloser’s Confidential Information that will be disclosed hereunder. 
 6.    Ownership.
All Confidential Information disclosed pursuant to this Agreement, including without limitation all written and tangible forms thereof, shall be and remain the property of the Discloser. Upon termination of this Agreement, if requested by Discloser,
Recipient shall return or destroy at Discloser’s discretion all of Discloser’s Confidential Information, provided that Recipient shall be entitled to keep one copy of such Confidential Information in a secure location solely for the
purpose of determining Recipient’s legal obligations hereunder. 
 7.    No License. Nothing in this
Agreement shall be construed as granting or conferring, expressly or impliedly, any rights by license or otherwise, under any patent, copyright, or other intellectual property rights owned or controlled by Discloser relating to Confidential
Information, except as specifically set forth in the License Agreement. 
 8.    Remedies. Each party acknowledges
that any breach of this Agreement by it may cause irreparable harm to the other party and that each party is entitled to seek injunctive relief and any other remedy available at law or in equity. 

9.    Export Restrictions. The Confidential Information is subject to the export and customs laws and regulations of
the United States and any other applicable country and neither party will export, re-export or transship, directly or indirectly, such information to any country without first obtaining proper governmental
approval, as necessary. Licensee will not disclose any export controlled information to BIDMC without the express prior written consent of BIDMC Technology Ventures Office. Licensee will indemnify BIDMC for any and all claims, actions, damages or
liabilities of any kind related to Company’s failure to comply with this section. 
 10.    General. These
Confidentiality Terms and Conditions, along with the License Agreement, contain the entire understanding of the parties with respect to the subject matter hereof, and supersede any prior oral or written understandings between the parties relating to
confidential treatment of information. Sections 1, 2, 4, 7, 10 and 11 of these Confidentiality Terms and Conditions shall survive any expiration or termination of the License Agreement. 

  
 20 

Portions of this Exhibit, indicated by the mark “[***],” were omitted and have been filed separately with the Securities and Exchange Commission
pursuant to the Registrant’s application requesting confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended.EX-10.9

 Exhibit 10.9 

LOAN AND SECURITY AGREEMENT 

THIS LOAN AND SECURITY AGREEMENT is made and dated as of October 19, 2018 and is entered into by and between X4 PHARMACEUTICALS, INC. a
Delaware corporation, and each of its Qualified Subsidiaries (hereinafter collectively referred to as the “Borrower”), the several banks and other financial institutions or entities from time to time parties to this Agreement
(collectively, referred to as “Lender”) and HERCULES CAPITAL, INC., a Maryland corporation, in its capacity as administrative agent and collateral agent for itself and the Lender (in such capacity, the “Agent”). 

RECITALS 
 A. Borrower has
requested Lender to make available to Borrower a loan in an aggregate principal amount of up to Thirteen Million ($13,000,000.00) (the “Term Loan”); and 

B.Lender is willing to make the Term Loan on the terms and conditions set forth in this Agreement. 

AGREEMENT 
 NOW,
THEREFORE, Borrower, Agent and Lender agree as follows: 
 SECTION 1 DEFINITIONS AND RULES OF CONSTRUCTION  

1.1 Unless otherwise defined herein, the following capitalized terms shall have the following meanings: 

“Account Control Agreement(s)” means any agreement entered into by and among the Agent, Borrower and a third party Bank or other
institution (including a Securities Intermediary) in which Borrower maintains a Deposit Account or an account holding Investment Property and which perfects Agent’s first priority security interest in the subject account or accounts. 

“ACH Authorization” means the ACH Debit Authorization Agreement in substantially the form of Exhibit H, which account numbers shall
be redacted for security purposes if and when filed publicly by the Borrower. 
 “Advance(s)” means a Term Loan Advance. 

“Advance Date” means the funding date of any Advance. 

“Advance Request” means a request for an Advance submitted by Borrower to Agent in substantially the form of Exhibit A, which
account numbers shall be redacted for security purposes if and when filed publicly by the Borrower. 

  
 1 

 “Affiliate” means, with respect to any person, (a) any Person that directly
or indirectly controls, is controlled by, or is under common control with the Person in question, (b) any Person directly or indirectly owning, controlling or holding with power to vote ten percent (10%) or more of the outstanding voting
securities of such Person, or (c) any Person ten percent (10%) or more of whose outstanding voting securities are directly or indirectly owned, controlled or held by such Person with power to vote such securities. As used in the definition of
“Affiliate,” the term “control” means the possession, directly or indirectly, of the power to direct or cause the direction of the management and policies of a Person, whether through ownership of voting securities, by contract
or otherwise. 
 “Agent” has the meaning given to it in the preamble to this Agreement. 

“Agreement” means this Loan and Security Agreement, as amended from time to time. 

“Amortization Date” means September 1, 2019; provided however, if Interest Only Extension Conditions A are achieved, then
March 1, 2020; and if Interest Only Extension Conditions B are achieved, then December 1, 2020. 
 “Anti-Corruption
Laws” shall mean all laws, rules, and regulations of any jurisdiction applicable to Borrower or any of its Affiliates from time to time concerning or relating to bribery or corruption, including without limitation the United States Foreign
Corrupt Practices Act of 1977, as amended, the UK Bribery Act 2010 and other similar legislation in any other jurisdictions. 

“Anti-Terrorism Laws” means any laws, rules, regulations or orders relating to terrorism or money laundering, including without
limitation Executive Order No. 13224 (effective September 24, 2001), the USA PATRIOT Act, the laws comprising or implementing the Bank Secrecy Act, and the laws administered by OFAC. 

“Assignee” has the meaning given to it in Section 11.13. 

“Blocked Person” means any Person: (a) listed in the annex to, or is otherwise subject to the provisions of, Executive Order
No. 13224, (b) a Person owned or controlled by, or acting for or on behalf of, any Person that is listed in the annex to, or is otherwise subject to the provisions of, Executive Order No. 13224, (c) a Person with which any Lender is
prohibited from dealing or otherwise engaging in any transaction by any Anti-Terrorism Law, (d) a Person that commits, threatens or conspires to commit or supports “terrorism” as defined in Executive Order No. 13224, or
(e) a Person that is named a “specially designated national” or “blocked person” on the most current list published by OFAC or other similar list. 

“Borrower Products” means all products, software, service offerings, technical data or technology currently being designed,
manufactured or sold by Borrower or which Borrower intends to sell, license, or distribute in the future including any products or service offerings under development, collectively, together with all products, software, service offerings, technical
data or technology that have been sold, licensed or distributed by Borrower since its incorporation. 
 “Business Day” means any
day other than Saturday, Sunday and any other day on which banking institutions in the State of California or the Commonwealth of Massachusetts are closed for business. 

  
 2 

 “Cash” means all cash, cash equivalents and liquid funds. 

“Change in Control” means any reorganization, recapitalization, consolidation or merger (or similar transaction or series of related
transactions) of Borrower, sale or exchange of outstanding shares (or similar transaction or series of related transactions) of Borrower in which the holders of Borrower’s outstanding shares immediately before consummation of such transaction
or series of related transactions do not, immediately after consummation of such transaction or series of related transactions, retain shares representing more than fifty percent (50%) of the voting power of the surviving entity of such transaction
or series of related transactions (or the parent of such surviving entity if such surviving entity is wholly owned by such parent), in each case without regard to whether Borrower is the surviving entity. Notwithstanding the foregoing, an Initial
Public Offering and any financing transaction related to Performance Milestone I or Performance Milestone II is not a Change of Control. 

“Charter” means Borrower’s Certificate of Incorporation, as amended from time to time. 

“Claims” has the meaning given to it in Section 11.10. 

“Closing Date” means the date of this Agreement. 

“Collateral” means the property described in Section 3. 

“Common Stock” means the Common Stock, $0.001 par value per share, of the Borrower. 

“Confidential Information” has the meaning given to it in Section 11.12. 

“Contingent Obligation” means, as applied to any Person, any direct or indirect liability, contingent or otherwise, of that Person
with respect to (i) any Indebtedness, dividend, letter of credit or other obligation of another, including any such obligation directly or indirectly guaranteed, endorsed, co-made or discounted or sold
with recourse by that Person, or in respect of which that Person is otherwise directly or indirectly liable; (ii) any obligations with respect to undrawn letters of credit, corporate credit cards or merchant services issued for the account of
that Person; and (iii) all obligations arising under any interest rate, currency or commodity swap agreement, interest rate cap agreement, interest rate collar agreement, or other agreement or arrangement designated to protect a Person against
fluctuation in interest rates, currency exchange rates or commodity prices; provided, however, that the term “Contingent Obligation” shall not include endorsements for collection or deposit in the ordinary course of business or guaranties
of leases that do not constitute Indebtedness. The amount of any Contingent Obligation shall be deemed to be an amount equal to the stated or determined amount of the primary obligation in respect of which such Contingent Obligation is made or, if
not stated or determinable, the maximum reasonably anticipated liability in respect thereof as determined by such Person in good faith; provided, however, that such amount shall not in any event exceed the maximum amount of the obligations under the
guarantee or other support arrangement. 

  
 3 

 “Copyright License” means any written agreement granting any right to use any
Copyright or Copyright registration, now owned or hereafter acquired by Borrower or in which Borrower now holds or hereafter acquires any interest. 

“Copyrights” means all copyrights, whether registered or unregistered, held pursuant to the laws of the United States of America,
any State thereof, or of any other country. 
 “Deposit Accounts” means any “deposit accounts,” as such term is defined
in the UCC, and includes any checking account, savings account, or certificate of deposit. 
 “Domestic Subsidiary” means any
Subsidiary that is not a Foreign Subsidiary. 
 “Due Diligence Fee” means $25,000, which fee has been paid to Lender prior to the
Closing Date, and shall be deemed fully earned on such date regardless of the early termination of this Agreement. 
 “Eligible Foreign
Subsidiary” means any Foreign Subsidiary whose execution of a Joinder Agreement could not result in a material adverse tax consequence to Borrower. 

“Equity Interests” means, with respect to any Person, the capital stock, partnership or limited liability company interest, or other
equity securities or equity ownership interests of such Person. 
 “ERISA” means the Employee Retirement Income Security Act of
1974, as amended, and the regulations promulgated thereunder. 
 “Event of Default” has the meaning given to it in Section 9.

 “Excluded Account” means any “zero balance” deposit account or securities account used exclusively for payroll,
employee benefits or employee taxes, the funds of which shall not exceed the amount required to pay the next payroll or other relevant cycle, and identified to the Agent in writing by the Borrower as such. 

“Facility Charge” means $65,000. 

“Financial Statements” has the meaning given to it in Section 7.1. 

“Foreign Subsidiary” means any Subsidiary other than a Subsidiary organized under the laws of any state within the United States of
America. 
 “GAAP” means generally accepted accounting principles in the United States of America, as in effect from time to time.

 “Indebtedness” means indebtedness of any kind, including (a) all indebtedness for borrowed money or the deferred purchase
price of property or services (excluding trade credit entered into in the ordinary course of business due within ninety (90) days), including reimbursement and other obligations with respect to surety bonds and letters of credit, (b) all
obligations evidenced by notes, bonds, debentures or similar instruments, (c) all capital lease obligations within the meaning of GAAP as in effect on the Closing Date, and (d) all Contingent Obligations; provided that Indebtedness shall
not include endorsements of checks or drafts arising in the ordinary course of business. 

  
 4 

 “Initial Public Offering” means the initial firm commitment underwritten offering
of Borrower’s Common Stock pursuant to a registration statement under the Securities Act of 1933 filed with and declared effective by the Securities and Exchange Commission. 

“Insolvency Proceeding” is any proceeding by or against any Person under the United States Bankruptcy Code, or any other bankruptcy
or insolvency law, including assignments for the benefit of creditors, compositions, extensions generally with its creditors, or proceedings seeking reorganization, arrangement, or other similar relief. 

“Intellectual Property” means all of Borrower’s Copyrights; Trademarks; Patents; Licenses; trade secrets and inventions; mask
works; Borrower’s applications therefor and reissues, extensions, or renewals thereof; and Borrower’s goodwill associated with any of the foregoing, together with Borrower’s rights to sue for past, present and future infringement of
Intellectual Property and the goodwill associated therewith. 
 “Interest Only Extension Conditions A” means satisfaction of each
of the following events: (a) no default or Event of Default shall have occurred and remains continuing; and (b) Borrower shall have received a Tranche 3 Term Loan Advance. 

“Interest Only Extension Conditions B” means satisfaction of each of the following events: (a) no default or Event of Default
shall have occurred and remains continuing; (b) Borrower shall have received a Tranche 3 Term Loan Advance; and (c) Borrower shall have achieved Performance Milestone II. 

“Inventory” means “inventory” as defined in Article 9 of the UCC. 

“Investment” means any beneficial ownership (including stock, partnership or limited liability company interests) of or in any
Person, or any loan, advance or capital contribution to any Person or the acquisition of any asset of another Person. 
 “IP Security
Agreement” means that certain Intellectual Property Security Agreement, executed and delivered by Borrower to Agent and dated as of the Closing Date. 

“Joinder Agreements” means for each Qualified Subsidiary, a completed and executed Joinder Agreement in substantially the form
attached hereto as Exhibit G. 
 “Lender” has the meaning given to it in the preamble to this Agreement. 

“License” means any Copyright License, Patent License, Trademark License or other license of rights or interests. 

“Lien” means any mortgage, deed of trust, pledge, hypothecation, assignment for security, security interest, encumbrance, levy, lien
or charge of any kind, whether voluntarily incurred or arising by operation of law or otherwise, against any property, any conditional sale or other title retention agreement, and any lease in the nature of a security interest. 

  
 5 

 “Loan” means the Advances made under this Agreement. 

“Loan Documents” means this Agreement, the Notes (if any), the ACH Authorization, the Account Control Agreements, the Joinder
Agreements, all UCC Financing Statements, the Warrant, the IP Security Agreement, the Pledge Agreement and any other documents executed in connection with the Secured Obligations or the transactions contemplated hereby, as the same may from time to
time be amended, modified, supplemented or restated. 
 “Material Adverse Effect” means a material adverse effect upon:
(i) the business, operations, properties, assets or financial condition of Borrower and its Subsidiaries taken as a whole; or (ii) the ability of Borrower to perform or pay the Secured Obligations in accordance with the terms of the Loan
Documents, or the ability of Agent or Lender to enforce any of its rights or remedies with respect to the Secured Obligations; or (iii) the Collateral or Agent’s Liens on the Collateral or the priority of such Liens. 

“Maximum Term Loan Amount” means Thirteen Million and No/100 Dollars ($13,000,000.00). 

“Maximum Rate” shall have the meaning assigned to such term in Section 2.3. 

“Non-Disclosure Agreement” means that certain Confidential Disclosure Agreement by and
between X4 Pharmaceuticals, Inc. and Hercules Capital, Inc. dated as of August 14, 2018. 
 “Note(s)” means a Term Note. 

“OFAC” is the U.S. Department of Treasury Office of Foreign Assets Control. 

“OFAC Lists” are, collectively, the Specially Designated Nationals and Blocked Persons List maintained by OFAC pursuant to Executive
Order No. 13224, 66 Fed. Reg. 49079 (Sept. 25, 2001) and/or any other list of terrorists or other restricted Persons maintained pursuant to any of the rules and regulations of OFAC or pursuant to any other applicable Executive Orders. 

“Patent License” means any written agreement granting any right with respect to any invention on which a Patent is in existence or a
Patent application is pending, in which agreement Borrower now holds or hereafter acquires any interest. 
 “Patents” means all
letters patent of, or rights corresponding thereto, in the United States of America or in any other country, all registrations and recordings thereof, and all applications for letters patent of, or rights corresponding thereto, in the United States
of America or any other country. 
 “Performance Milestone I” means Borrower shall have: (a) obtained a minimum of
$45,000,000 in unrestricted (including, not subject to any redemption, clawback, escrow or similar restriction) gross cash proceeds from an equity financing (or a series of equity financings), 

  
 6 

 
including through private financings led by an institutional investor reasonably acceptable to Lender and/or public offerings, during the period commencing on the Closing Date through
March 31, 2019, including an amount of up to $7,500,000 of investor funded indebtedness converted into equity in such financing(s), subject to verification by Agent (including supporting documentation requested by Agent); and (b) achieved
the “First Patient In” Phase 3 portion of a Phase 2/3 clinical evaluation of X4P-001 in patients with WHIM. 

“Performance Milestone II” means Borrower shall have: (a) achieved Performance Milestone I, and (b) obtained a minimum of
$80,000,000 (inclusive of amounts raised to achieve Performance Milestone I) in unrestricted (including, not subject to any redemption, clawback, escrow or similar restriction) gross cash proceeds from an equity financing (or a series of equity
financings), including through private financings and/or public offerings, during the period commencing on the Closing Date through December 31, 2019, including an amount of up to $7,500,000 of investor funded indebtedness converted into equity
in such financings to the extent not previously converted in connection with Performance Milestone I, subject to verification by Agent (including supporting documentation requested by Agent). 

“Permitted Indebtedness” means: (i) Indebtedness of Borrower in favor of Lender or Agent arising under this Agreement or any
other Loan Document; (ii) Indebtedness existing on the Closing Date which is disclosed in Schedule 1A; (iii) Indebtedness of up to $500,000 outstanding at any time secured by a Lien described in clause (vii) of the defined term
“Permitted Liens,” provided such Indebtedness does not exceed the cost of the Equipment financed with such Indebtedness; (iv) Indebtedness to trade creditors incurred in the ordinary course of business, and Indebtedness incurred in
the ordinary course of business with corporate credit cards; (v) Indebtedness that also constitutes a Permitted Investment; (vi) Subordinated Indebtedness; (vii) reimbursement obligations in connection with letters of credit that are
secured by Cash and issued on behalf of the Borrower or a Subsidiary thereof in an amount not to exceed $200,000 at any time outstanding, (viii) other unsecured Indebtedness in a principal amount not to exceed $200,000 at any time outstanding,
(ix) intercompany Indebtedness as long as either (A) each of the Subsidiary obligor and the Subsidiary obligee under such Indebtedness is a Qualified Subsidiary that has executed a Joinder Agreement and (x) extensions, amendments,
restatements, refinancings and renewals of any items of Permitted Indebtedness, provided that the principal amount is not increased or the terms modified to impose materially more burdensome terms upon Borrower or its Subsidiary, as the case may be.

 “Permitted Investment” means: (i) Investments existing on the Closing Date which are disclosed in Schedule 1B;
(ii) (a) marketable direct obligations issued or unconditionally guaranteed by the United States of America or any agency or any State thereof maturing within one year from the date of acquisition thereof currently having a rating of at least A-2 or P-2 from either Standard & Poor’s Corporation or Moody’s Investors Services, (b) commercial paper maturing no more than one year from the date
of creation thereof and currently having a rating of at least A-2 or P-2 from either Standard & Poor’s Corporation or Moody’s Investors Service,
(c) certificates of deposit issued by any bank with assets of at least $500,000,000 maturing no more than one year from the date of investment therein, and (d) money market accounts; (iii) repurchases of stock from current or former
employees, directors, or consultants of Borrower under the terms of applicable repurchase agreements at the original issuance price of such securities in an aggregate amount not to exceed $250,000 in any fiscal year, provided that no Event of
Default has occurred 

  
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and is continuing or would immediately result after giving effect to the repurchases; (iv) Investments consisting of the endorsement of negotiable instruments for deposit or collection or
similar transactions in the ordinary course of business; (v) Investments accepted in connection with Permitted Transfers; (vi) Investments (including debt obligations) received in connection with the bankruptcy or reorganization of
customers or suppliers and in settlement of delinquent obligations of, and other disputes with, customers or suppliers arising in the ordinary course of Borrower’s business; (vii) Investments consisting of notes receivable of, or prepaid
royalties and other credit extensions, to customers and suppliers who are not Affiliates, in the ordinary course of business, provided that this subparagraph (vii) shall not apply to Investments of Borrower in any Subsidiary;
(viii) Investments consisting of loans not involving the net transfer on a substantially contemporaneous basis of cash proceeds to employees, officers or directors relating to the purchase of capital stock of Borrower pursuant to employee stock
purchase plans or other similar agreements approved by Borrower’s Board of Directors; (ix) Investments consisting of travel advances, employee relocation loans, and other employee loans and advances in the ordinary course of business in an
aggregate amount not to exceed $250,000 in any fiscal year or $500,000 during the term hereof; (x) Investments in newly-formed Domestic Subsidiaries, provided that each such Domestic Subsidiary other than one (1) Security Corporation
enters into a Joinder Agreement promptly after its formation by Borrower and execute such other documents as shall be reasonably requested by Agent; (xi) Investments in Foreign Subsidiaries approved in advance in writing by Agent;
(xii) joint ventures or strategic alliances in the ordinary course of Borrower’s business consisting of the licensing of technology, the development of technology or the providing of technical support, provided that any cash Investments by
Borrower do not exceed $500,000 in the aggregate in any fiscal year; (xiii) Investments in one (1) Subsidiary qualifying as a “security corporation” under Massachusetts law (a “Security Corporation”); and
(xiv) additional Investments that do not exceed $250,000 in the aggregate. 
 “Permitted Liens” means any and all of the
following: (i) Liens in favor of Agent or Lender; (ii) Liens existing on the Closing Date which are disclosed in Schedule 1C; (iii) Liens for taxes, fees, assessments or other governmental charges or levies, either not delinquent or
being contested in good faith by appropriate proceedings; provided, that Borrower maintains adequate reserves therefor in accordance with GAAP (to the extent required hereby); (iv) Liens securing claims or demands of materialmen, artisans,
mechanics, carriers, warehousemen, landlords and other like Persons arising in the ordinary course of Borrower’s business and imposed without action of such parties; provided, that the payment thereof is not yet required; (v) Liens arising
from judgments, decrees or attachments in circumstances which do not constitute an Event of Default hereunder; (vi) deposits to secure the performance of obligations not to exceed $100,000 in the aggregate, and the following deposits, to the
extent made in the ordinary course of business: deposits under worker’s compensation, unemployment insurance, social security and other similar laws, or to secure the performance of bids, tenders or contracts (other than for the repayment of
borrowed money) or to secure indemnity, performance or other similar bonds for the performance of bids, tenders or contracts (other than for the repayment of borrowed money) or to secure statutory obligations (other than Liens arising under ERISA or
environmental Liens) or surety or appeal bonds, or to secure indemnity, performance or other similar bonds; (vii) Liens on Equipment or software or other intellectual property constituting purchase money Liens and Liens in connection with
capital leases securing Indebtedness permitted in clause (iii) of “Permitted Indebtedness”; (viii) Liens incurred in connection with Subordinated Indebtedness; (ix) leasehold interests in leases or subleases and licenses or
sublicenses granted in the ordinary course of 

  
 8 

 
business and not interfering in any material respect with the business of the lessor licensor, as applicable; (x) Liens in favor of customs and revenue authorities arising as a matter of law
to secure payment of custom duties that are promptly paid on or before the date they become due; (xi) Liens on insurance proceeds securing the payment of financed insurance premiums that are promptly paid on or before the date they become due
(provided that such Liens extend only to such insurance proceeds and not to any other property or assets); (xii) statutory and common law rights of set-off and other similar rights as to deposits of cash and
securities in favor of banks, other depository institutions and brokerage firms; (xiii) easements, zoning restrictions, rights-of-way and similar encumbrances on
real property imposed by law or arising in the ordinary course of business so long as they do not materially impair the value or marketability of the related property; (xiv) (A) Liens on Cash securing obligations permitted under clause
(vii) of the definition of Permitted Indebtedness and (B) security deposits in connection with real property leases, the combination of (A) and (B) in an aggregate amount not to exceed $200,000 at any time; (xv) Liens incurred in
connection with the extension, renewal or refinancing of the Indebtedness secured by Liens of the type described in clauses (i) through (xi) above; provided, that any extension, renewal or replacement Lien shall be limited to the property
encumbered by the existing Lien and the principal amount of the Indebtedness being extended, renewed, refinanced, modified, amended, restated or amended and restated (as may have been reduced by any payment thereon) does not increase; and
(xvi) other Liens securing obligations not to exceed the principal amount of $250,000 outstanding at any time. 
 “Permitted
Transfers” means (i) sales of Inventory in the ordinary course of business, (ii) non-exclusive outbound licenses and similar arrangements for the use of Intellectual Property in the ordinary
course of business, (iii) exclusive licenses for the use of the Intellectual Property of Borrower or Borrower Products in the field of Immuno-Oncology entered into the ordinary course of business provided that each such license constitutes an
arms-length transaction, that could not result in a legal transfer of title of the licensed property, and so long as after giving effect to each such non-exclusive or exclusive license, Borrower and its
Subsidiaries retain sufficient rights to use or benefit from the subject Intellectual Property as to enable them to conduct their business in the ordinary course, (iv) dispositions of worn-out, obsolete
or surplus Equipment at fair market value in the ordinary course of business, (v) transfers consisting of Permitted Investments or Permitted Liens, (vi) transfers of Cash in the ordinary course of business to the extent not otherwise
inconsistent with the terms and conditions of this Agreement, and (vii) other Transfers of assets having a fair market value of not more than $250,000 in the aggregate in any fiscal year. 

“Person” means any individual, sole proprietorship, partnership, joint venture, trust, unincorporated organization, association,
corporation, limited liability company, institution, other entity or government. 
 “Pledge Agreement” means the Pledge Agreement
dated as of the Closing Date between Borrower and Agent, as the same may from time to time be amended, restated, modified or otherwise supplemented. 

“Preferred Stock” means at any given time any equity security issued by Borrower that has any rights, preferences or privileges
senior to Borrower’s Common Stock. 

  
 9 

 “Prepayment Charge” shall have the meaning assigned to such term in
Section 2.5. 
 “Qualified Subsidiary” means any direct or indirect Domestic Subsidiary (other than one (1) Security
Corporation) or Eligible Foreign Subsidiary. 
 “Receivables” means (i) all of Borrower’s Accounts, Instruments,
Documents, Chattel Paper, Supporting Obligations, letters of credit, proceeds of any letter of credit, and Letter of Credit Rights, and (ii) all customer lists, software, and business records related thereto. 

“Required Lenders” means at any time, the holders of more than 50% of the aggregate unpaid principal amount of the Term Loans then
outstanding. 
 “Sanctioned Country” shall mean, at any time, a country or territory which is the subject or target of any
Sanctions. 
 “Sanctioned Person” shall mean, at any time, (a) any Person listed in any Sanctions-related list of designated
Persons maintained by the Office of Foreign Assets Control of the U.S. Department of the Treasury or the U.S. Department of State, or by the United Nations Security Council, the European Union or any EU member state, (b) any Person operating,
organized or resident in a Sanctioned Country or (c) any Person controlled by any such Person. 
 “Sanctions” shall mean
economic or financial sanctions or trade embargoes imposed, administered or enforced from time to time by (a) the U.S. government, including those administered by the Office of Foreign Assets Control of the U.S. Department of the Treasury or
the U.S. Department of State, or (b) the United Nations Security Council, the European Union or Her Majesty’s Treasury of the United Kingdom. 

“SBA” shall have the meaning assigned to such term in Section 7.16. 

“SBIC” shall have the meaning assigned to such term in Section 7.16. 

“SBIC Act” shall have the meaning assigned to such term in Section 7.16. 

“SEC” means the Securities and Exchange Commission, or any successor thereto. 

“Secured Obligations” means Borrower’s obligations under this Agreement and any Loan Document (other than the Warrant),
including any obligation to pay any amount now owing or later arising. 
 “Subordinated Indebtedness” means Indebtedness
subordinated to the Secured Obligations in amounts and on terms and conditions satisfactory to Agent in its sole discretion and subject to a written subordination agreement in form and substance satisfactory to Agent in its sole discretion. 

“Subsequent Financing” means the closing of any Borrower institutional financing which becomes effective after the Closing Date, but
specifically excluding Borrower’s Series B Preferred financing round, and Borrower’s Initial Public Offering. 

  
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 “Subsidiary” means an entity, whether corporate, partnership, limited liability
company, joint venture or otherwise, in which Borrower owns or controls 50% or more of the outstanding voting securities, including each entity listed on Schedule 1 hereto. 

“Term Commitment” means as to any Lender, the obligation of such Lender, if any, to make a Term Loan Advance to the Borrower in a
principal amount not to exceed the amount set forth under the heading “Term Commitment” opposite such Lender’s name on Schedule 1.1. 

“Term Loan Advance” means any Term Loan funds advanced under this Agreement. 

“Term Loan Maturity Date” means November 1, 2021, provided however, if Borrower receives a Tranche 2 Term Loan Advance, and no
default or Event of Default shall have occurred and be continuing, then May 1, 2022. 
 “Term Note” means a Promissory Note
in substantially the form of Exhibit B. 
 “Trademark License” means any written agreement granting any right to use any Trademark
or Trademark registration, now owned or hereafter acquired by Borrower or in which Borrower now holds or hereafter acquires any interest. 

“Trademarks” means all trademarks (registered, common law or otherwise) and any applications in connection therewith, including
registrations, recordings and applications in the United States Patent and Trademark Office or in any similar office or agency of the United States of America, any State thereof or any other country or any political subdivision thereof. 

“Tranche 1 Term Loan Advance” shall mean a Term Loan Advance with the meaning assigned to such term in Section 2.2(a)(i). 

“Tranche 1 Warrant” means that certain Warrant to purchase a number of shares of Borrower’s Preferred Stock at an aggregate
exercise price equal to $396,000 issued by Borrower to Lender on the Closing Date in connection with the extension of the Tranche 1 Term Loan Advance. 

“Tranche 1 Term Loan Interest Rate” means for any day a per annum rate of interest equal to the greater of either (i) 9.50% plus the
prime rate as reported in The Wall Street Journal minus 5.25%, and (ii) 9.50%. 
 “Tranche 2 Term Loan Advance” shall mean a Term
Loan Advance with the meaning assigned to such term in Section 2.2(a)(ii). 
 “Tranche 2 Warrant” means that certain Warrant
issued by Borrower to Lender on the date Borrower draws the Tranche 2 Term Loan Advance in connection with the extension of the Tranche 2 Term Loan Advance; if the Tranche 2 Term Loan Advance is drawn before Borrower achieves Performance Milestone
I, the aggregate exercise price shall be $99,000, but if the Tranche 2 Term Loan Advance is drawn after Borrower achieves Performance Milestone I, then the aggregate exercise price shall be $40,000. 

  
 11 

 “Tranche 3 Term Loan Advance” shall mean a Term Loan Advance with the meaning
assigned to such term in Section 2.2(a)(iii). 
 “Tranche 3 Term Loan Interest Rate” means for any day a per annum rate of
interest equal to the greater of either (i) 8.75% plus the prime rate as reported in The Wall Street Journal minus 5.25%, and (ii) 8.75%. 

“Tranche 3 Warrant” means that certain Warrant to purchase a number of shares of Borrower’s Preferred Stock at an aggregate
exercise price equal to $60,000 issued by Borrower to Lender on the date Borrower draws the Tranche 3 Term Loan Advance in connection with the extension of the Tranche 3 Term Loan Advance. 

“UCC” means the Uniform Commercial Code as the same is, from time to time, in effect in the State of California; provided, that in
the event that, by reason of mandatory provisions of law, any or all of the attachment, perfection or priority of, or remedies with respect to, Agent’s Lien on any Collateral is governed by the Uniform Commercial Code as the same is, from time
to time, in effect in a jurisdiction other than the State of California, then the term “UCC” shall mean the Uniform Commercial Code as in effect, from time to time, in such other jurisdiction solely for purposes of the provisions thereof
relating to such attachment, perfection, priority or remedies and for purposes of definitions related to such provisions. 

“Warrant” means any warrant, including the Tranche 1 Warrant, the Tranche 2 Warrant and the Tranche 3 Warrant, entered into in
connection with the Loan, as may be amended, restated or modified from time to time. 
 Unless otherwise specified, all references in this
Agreement or any Annex or Schedule hereto to a “Section,” “subsection,” “Exhibit,” “Annex,” or “Schedule” shall refer to the corresponding Section, subsection, Exhibit, Annex, or Schedule in or to
this Agreement. Unless otherwise specifically provided herein, any accounting term used in this Agreement or the other Loan Documents shall have the meaning customarily given such term in accordance with GAAP, and all financial computations
hereunder shall be computed in accordance with GAAP, consistently applied. Unless otherwise defined herein or in the other Loan Documents, terms that are used herein or in the other Loan Documents and defined in the UCC shall have the meanings given
to them in the UCC. 
 SECTION 2 THE LOAN 

2.1 [Intentionally omitted.] 

2.2 Term Loan. 
  

	 	(a)	 Advances. 

  

	 	(i)	 Tranche 1 Term Loan Advances. Subject to the terms and conditions of this Agreement, Lender will severally (and
not jointly) make in an amount not to exceed its respective Term Commitment, and Borrower agrees to draw, a Term Loan Advance of $8,000,000 (a “Tranche 1 Term Loan Advance”) on the Closing Date. 

  
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	 	(ii)	 Tranche 2 Term Loan Advance. Subject to the terms and conditions of this Agreement, beginning on
January 1, 2019 and continuing through March 31, 2019, and subject to Borrower’s satisfactory progress towards the achievement of Performance Milestone I in Lender’s sole discretion, Borrower may request and Lender will make a
Term Loan Advance of $2,000,000 (the “Tranche 2 Term Loan Advance”). 

  

	 	(iii)	 Tranche 3 Term Loan Advance. Subject to the terms and conditions of this Agreement and Borrower’s prior
receipt of the Tranche 2 Term Loan Advance, beginning on the date Borrower achieves Performance Milestone I and continuing through March 31, 2019, Borrower may request and Lender will make a Term Loan Advance of $3,000,000 (the “Tranche 3
Term Loan Advance”). 

 Subject to the terms above, the aggregate outstanding Term Loan Advances may be up to the
Maximum Term Loan Amount. 
 (b) Advance Request. To obtain a Term Loan Advance, Borrower shall complete, sign and deliver an
Advance Request (at least three (3) Business Days before the Advance Date other than with respect to the Tranche 1 Term Loan Advance, which shall be at least one (1) Business Day) to Agent. Lender shall fund the Term Loan Advance in the
manner requested by the Advance Request provided that each of the conditions precedent to such Term Loan Advance is satisfied as of the requested Advance Date. 

(c) Term Loan Interest Rate. 
  

	 	(i)	 Tranche 1 Term Loan Advance. The principal balance of the Tranche 1 Term Loan Advance shall bear interest
thereon from such Advance Date at the Tranche 1 Term Loan Interest Rate based on a year consisting of 360 days, with interest computed daily based on the actual number of days elapsed. 

 

	 	(ii)	 Tranche 2 Term Loan Advance. If the Tranche 2 Term Loan Advance is drawn before Borrower achieves Performance
Milestone I, the principal balance of the Tranche 2 Term Loan Advance shall bear interest thereon from such Advance Date at the Tranche 1 Term Loan Interest Rate based on a year consisting of 360 days, with interest computed daily based on the
actual number of days elapsed. If the Tranche 2 Term Loan Advance is drawn after Borrower achieves Performance Milestone I, the principal balance of the Tranche 2 Term Loan Advance shall bear interest thereon from such Advance Date at the Tranche 3
Term Loan Interest Rate based on a year consisting of 360 days, with interest computed daily based on the actual number of days elapsed. 

  
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	 	(iii)	 Tranche 3 Term Loan Advance. The principal balance of the Tranche 3 Term Loan Advance shall bear interest
thereon from the applicable Advance Date at the Tranche 3 Term Loan Interest Rate based on a year consisting of 360 days, with interest computed daily based on the actual number of days elapsed. 

The Tranche 1 Term Loan Interest Rate and the Tranche 3 Term Loan Interest Rate will float and change on the day the prime rate changes from
time to time. 
 (d) Payment. Borrower will pay interest on each Term Loan Advance on the first Business Day of each month,
beginning the month after the corresponding Advance Date. Borrower shall repay the aggregate Term Loan principal balance that is outstanding on the day immediately preceding the Amortization Date, in equal monthly installments of principal and
interest (mortgage style) beginning on the Amortization Date and continuing on the first Business Day of each month thereafter until the Secured Obligations (other than inchoate indemnity obligations and other obligations that are stated to survive
termination of this Agreement) are repaid. The entire Term Loan principal balance and all accrued but unpaid interest hereunder, shall be due and payable on Term Loan Maturity Date. Borrower shall make all payments under this Agreement without
setoff, recoupment or deduction and regardless of any counterclaim or defense. Lender will initiate debit entries to the Borrower’s account as authorized on the ACH Authorization (i) on each payment date of all periodic obligations payable
to Lender under each Term Advance and (ii) reasonable and documented out-of-pocket legal fees and costs incurred by Agent or Lender in connection with
Section 11.11 of this Agreement; provided that, with respect to clause (i) above, in the event that Lender or Agent informs Borrower that Lender will not initiate a debit entry to Borrower’s account for a certain amount of the
periodic obligations due on a specific payment date, Borrower shall pay to Lender such amount of periodic obligations in full in immediately available funds on such payment date; provided, further, that, with respect to clause (i) above, if
Lender or Agent informs Borrower that Lender will not initiate a debit entry as described above later than the date that is three (3) Business Days prior to such payment date, Borrower shall pay to Lender such amount of periodic obligations in
full in immediately available funds on the date that is three (3) Business Days after the date on which Lender or Agent notifies Borrower of such; provided, further, that, with respect to clause (ii) above, in the event that Lender or
Agent informs Borrower that Lender will not initiate a debit entry to Borrower’s account for certain amount of such out-of-pocket legal fees and costs incurred by
Agent or Lender, Borrower shall pay to Lender such amount in full in immediately available funds within three (3) Business Days. 

2.3 Maximum Interest. Notwithstanding any provision in this Agreement or any other Loan Document, it is the parties’
intent not to contract for, charge or receive interest at a rate that is greater than the maximum rate permissible by law that a court of competent jurisdiction shall deem applicable hereto (which under the laws of the State of California shall be
deemed to be the laws relating to permissible rates of interest on commercial loans) (the “Maximum Rate”). If a court of competent jurisdiction shall 

  
 14 

 
finally determine that Borrower has actually paid to Lender an amount of interest in excess of the amount that would have been payable if all of the Secured Obligations had at all times borne
interest at the Maximum Rate, then such excess interest actually paid by Borrower shall be applied as follows: first, to the payment of the Secured Obligations consisting of the outstanding principal; second, after all principal is repaid, to the
payment of Lender’s accrued interest, costs, expenses, professional fees and any other Secured Obligations permitted under this Agreement; and third, after all Secured Obligations are repaid, the excess (if any) shall be refunded to Borrower.

 2.4 Default Interest. In the event any payment is not paid on the scheduled payment date, an amount equal to four percent
(4%) of the past due amount shall be payable on demand. In addition, upon the occurrence and during the continuation of an Event of Default hereunder, all unpaid Secured Obligations, including principal, interest, compounded interest, and
professional fees, shall bear interest at a rate per annum equal to the rate set forth in 2.2(c), plus four percent (4%) per annum. In the event any interest is not paid when due hereunder, delinquent interest shall be added to principal and shall
bear interest on interest, compounded at the rate set forth in 2.2(c) or Section 2.4, as applicable. 
 2.5 Prepayment.
At its option upon at least seven (7) Business Days prior written notice to Agent (or such shorter notice period as agreed by Agent in its discretion), Borrower may prepay all, but not less than all, of the outstanding Advances by paying the
entire principal balance, all accrued and unpaid interest thereon, together with a prepayment charge equal to the following percentage of the Advance amount being prepaid: if such prepayment is made (a) during any of the first twelve
(12) months following the Closing Date, 2.0%; (b) after twelve (12) months but prior to twenty four (24) months following the Closing Date, 1.0%; and (c) after twenty four (24) months following the Closing Date, but prior to
the Term Loan Maturity Date, 0.5% (each, a “Prepayment Charge”). Borrower agrees that the Prepayment Charge is a reasonable calculation of Lender’s lost profits in view of the difficulties and impracticality of determining actual
damages resulting from an early repayment of the Advances. Borrower shall prepay the outstanding amount of all principal and accrued interest through the prepayment date and the Prepayment Charge upon the occurrence of a Change in Control.
Notwithstanding the foregoing, Agent and Lender agree to waive the Prepayment Charge if Agent and Lender (in its sole and absolute discretion) agree in writing to refinance the Advances prior to the Term Loan Maturity Date. 

2.6 End of Term Charges. 

(a) On the earliest to occur of (i) the Term Loan Maturity Date, (ii) the date that Borrower prepays the outstanding
Secured Obligations (other than any inchoate indemnity obligations and any other obligations which, by their terms, are to survive the termination of this Agreement) in full, or (iii) the date that the Secured Obligations become due and
payable, Borrower shall pay Lender a charge of $636,000 in connection with the Tranche 1 Term Loan Advance. Notwithstanding the required payment date of such charge, it shall be deemed earned by Lender as of the Closing Date. 

  
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 (b) On the earliest to occur of (i) the Term Loan Maturity Date,
(ii) the date that Borrower prepays the outstanding Secured Obligations (other than any inchoate indemnity obligations and any other obligations which, by their terms, are to survive the termination of this Agreement) in full, or (iii) the
date that the Secured Obligations become due and payable, Borrower shall pay Lender a charge of $159,000 in connection with the Tranche 2 Term Loan Advance if the Term 2 Term Loan Advance is drawn before Borrower achieves Performance Milestone I,
but if the Tranche 2 Term Loan Advance is drawn after Borrower achieves Performance Milestone I, then Borrower shall instead pay Lender a charge of $105,000. Notwithstanding the required payment date of such charge, it shall be deemed earned by
Lender as of the Closing Date, to the extent Borrower draws the Tranche 2 Term Loan Advance. 
 (c) On the earliest to occur
of (i) the Term Loan Maturity Date, (ii) the date that Borrower prepays the outstanding Secured Obligations (other than any inchoate indemnity obligations and any other obligations which, by their terms, are to survive the termination of
this Agreement) in full, or (iii) the date that the Secured Obligations become due and payable, Borrower shall pay Lender a charge of $157,500 in connection with the Tranche 3 Term Loan Advance. Notwithstanding the required payment date of such
charge, it shall be deemed earned by Lender as of the Closing Date, to the extent Borrower draws the Tranche 3 Term Loan Advance. 

2.7 Notes. If so requested by Lender by written notice to Borrower, then Borrower shall execute and deliver to Lender (and/or,
if applicable and if so specified in such notice, to any Person who is an assignee of Lender pursuant to Section 11.13) (promptly after the Borrower’s receipt of such notice) a Note or Notes to evidence Lender’s Loans. 

2.8 Pro Rata Treatment. Each payment (including prepayment) on account of any fee and any reduction of the Term Loans shall be
made pro rata according to the Term Commitments of the relevant Lender. 
 SECTION 3 SECURITY INTEREST 

3.1 As security for the prompt and complete payment when due (whether on the payment dates or otherwise) of all the Secured
Obligations, Borrower grants to Agent a security interest in all of Borrower’s right, title, and interest in, to and under all of Borrower’s personal property and other assets including without limitation the following (except as set forth
herein) whether now owned or hereafter acquired (collectively, the “Collateral”): (a) Receivables; (b) Equipment; (c) Fixtures; (d) General Intangibles; (e) Inventory; (f) Investment Property; (g) Deposit Accounts;
(h) Cash; (i) Goods; and all other tangible and intangible personal property of Borrower whether now or hereafter owned or existing, leased, consigned by or to, or acquired by, Borrower and wherever located, and any of Borrower’s property
in the possession or under the control of Agent; and, to the extent not otherwise included, all Proceeds of each of the foregoing and all accessions to, substitutions and replacements for, and rents, profits and products of each of the foregoing.
Notwithstanding the above, upon Borrower’s achievement of Performance Milestone I, Agent shall promptly release its lien on Intellectual Property, 

  
 16 

 
provided, however, that from and after such release, the Collateral shall include all Accounts and General Intangibles that consist of rights to payment and proceeds from the sale, licensing or
disposition of all or any part, or rights in, the Intellectual Property (the “Rights to Payment”). Notwithstanding the foregoing, if a judicial authority (including a U.S. Bankruptcy Court) holds that a security interest in the underlying
Intellectual Property is necessary to have a security interest in the Rights to Payment, then the Collateral shall automatically, and effective as of the date of this Agreement, include the Intellectual Property to the extent necessary to permit
perfection of Agent’s security interest in the Rights to Payment. 
 3.2 Notwithstanding the broad grant of the security
interest set forth in Section 3.1 above, the Collateral shall not include (a) more than 65% of the presently existing and hereafter arising issued and outstanding shares of capital stock owned by Borrower of any Foreign Subsidiary (other
than an Eligible Foreign Subsidiary) which shares entitle the holder thereof to vote for directors or any other matter, (b) any “intent to use” trademarks at all times prior to the first use thereof, whether by the actual use thereof
in commerce, the recording of a statement of use with the United States Patent and Trademark Office or otherwise, provided, that upon submission and acceptance by the United States Patent and Trademark Office of an amendment to allege use of
an intent-to-use trademark application pursuant to 15 U.S.C. Section 1060(a) (or any successor provision) such intent-to-use application shall constitute Collateral, (c) nonassignable licenses or contracts, which by their terms require the consent of the licensor thereof or another party (but only to the extent
such prohibition on transfer is enforceable under applicable law, including, without limitation, Sections 9406, 9407 and 9408 of the UCC), and (d) any leasehold real property interest, license, lease or other contract or agreement or any
property subject to a purchase money security interest or similar arrangement to the extent that a grant of a security interest therein would violate or invalidate such lease, license, contract or agreement or purchase money arrangement or create a
right of termination in favor of any other party thereto (but only to the extent such prohibition on transfer or grant of a security interest is enforceable under applicable law, including, without limitation, Sections 9406, 9407 and 9408 of the
UCC), (e) any property to the extent that, and for as long as, such grant of a security interest is prohibited by any applicable law, rule or regulation; provided that the foregoing exclusion in this clause (e) shall in no way be construed
(i) to apply to the extent that any described prohibition is unenforceable under Section 9406, 9407 or 9408 of the UCC or other applicable law or (ii) to apply to the extent that any consent or waiver has been obtained, or is
hereafter obtained, that would permit the Agent’s security interest or Lien notwithstanding the prohibition on the grant of a security interest in such property (f) Excluded Accounts, (g) motor vehicles or other assets in which a
security interest may be perfected only though compliance with a certificate of title statute, (h) any property subject to the Sanofi Agreement as disclosed on Schedule 3.2 hereto, and (i) any Cash securing reimbursement obligations
permitted under this Agreement. 

  
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 SECTION 4 CONDITIONS PRECEDENT TO LOAN 

The obligations of Lender to make the Loan hereunder are subject to the satisfaction by Borrower of the following conditions: 

4.1 Initial Advance. On or prior to the Closing Date, Borrower shall have delivered to Agent the following: 

(a) executed copies of the Loan Documents (other than the Tranche 1 Warrant, which shall be an original), Account Control
Agreements, and all other documents and instruments reasonably required by Agent to effectuate the transactions contemplated hereby or to create and perfect the Liens of Agent with respect to all Collateral, in all cases in form and substance
reasonably acceptable to Agent; 
 (b) certified copy of resolutions of Borrower’s board of directors evidencing
approval of (i) the Loan and other transactions evidenced by the Loan Documents; and (ii) the Warrant and transactions evidenced thereby; 

(c) certified copies of the Certificate of Incorporation and the Bylaws, as amended through the Closing Date, of Borrower; 

(d) a certificate of good standing for Borrower from its state of incorporation and similar certificates from all other
jurisdictions in which it does business and where the failure to be qualified could have a Material Adverse Effect; 
 (e)
payment of the Facility Charge and reimbursement of Agent’s and Lender’s reasonable and documented expenses reimbursable pursuant to this Agreement, which amounts may be deducted from the initial Advance; 

(f) all certificates of insurance with respect to insurance required hereunder; and 

(g) such other documents as Agent may reasonably request. 

4.2 All Advances. On each Advance Date: 

(a) Agent shall have received (i) an Advance Request for the relevant Advance as required by 2.2(b), each duly executed by
Borrower’s Chief Executive Officer or Chief Financial Officer, (ii) the Tranche 2 Warrant or Tranche 3 Warrant, as applicable, and (iii) any other documents Agent may reasonably request. 

(b) The representations and warranties set forth in this Agreement shall be true and correct in all material respects on and as
of the Advance Date with the same effect as though made on and as of such date, except to the extent such representations and warranties expressly relate to an earlier date, and representations and warranties that may be updated pursuant to this
Agreement shall be true and correct in all material respects as of the date made, provided that such updated representations and warranties shall not apply to an earlier date and shall not cure any default arising from any false or incorrect
representations and warranties previously made. 
 (c) Borrower shall be in compliance with all the terms and provisions set
forth herein and in each other Loan Document on its part to be observed or performed, and at the time of and immediately after such Advance no Event of Default shall have occurred and be continuing. 

  
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 (d) Each Advance Request shall be deemed to constitute a representation and
warranty by Borrower on the relevant Advance Date as to the matters specified in paragraphs (b) and (c) of this Section 4.2 and as to the matters set forth in the Advance Request. 

4.3 No Default. As of the Closing Date and each Advance Date, (i) no fact or condition exists that could reasonably (or
could reasonably, with the passage of time, the giving of notice, or both) constitute an Event of Default and (ii) no event that has had or could reasonably be expected to have a Material Adverse Effect has occurred and is continuing. 

SECTION 5 REPRESENTATIONS AND WARRANTIES OF BORROWER 

Borrower represents and warrants that: 

5.1 Corporate Status. Borrower is a corporation duly organized, legally existing and in good standing under the laws of the
State of Delaware, and is duly qualified as a foreign corporation in all jurisdictions in which the nature of its business or location of its properties require such qualifications and where the failure to be qualified could reasonably be expected
to have a Material Adverse Effect. Borrower’s present name, former names (if any), locations, place of formation, tax identification number, organizational identification number and other information are correctly set forth in Exhibit C, as may
be updated by Borrower in a written notice (including any Compliance Certificate) provided to Agent after the Closing Date. 

5.2 Collateral. Borrower owns the Collateral, including, as applicable, the Intellectual Property, free of all Liens, except
for Permitted Liens. Borrower has the power and authority to grant to Agent a Lien in the Collateral as security for the Secured Obligations. 

5.3 Consents. Borrower’s execution, delivery and performance of this Agreement and all other Loan Documents, and
Borrower’s execution of the Warrant, (i) have been duly authorized by all necessary corporate action of Borrower, (ii) will not result in the creation or imposition of any Lien upon the Collateral, other than Permitted Liens and the
Liens created by this Agreement and the other Loan Documents, (iii) do not violate any provisions of Borrower’s Certificate or Articles of Incorporation (as applicable), bylaws, or any, law, regulation, order, injunction, judgment, decree
or writ to which Borrower is subject and (iv) except as described on Schedule 5.3, do not violate any material contract or agreement or require the consent or approval of any other Person which has not already been obtained. The individual or
individuals executing the Loan Documents and the Warrant are duly authorized to do so. 
 5.4 Material Adverse Effect. No
event that has had or could reasonably be expected to have a Material Adverse Effect has occurred and is continuing. Borrower is not aware of any event likely to occur that is reasonably expected to result in a Material Adverse Effect. 

  
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 5.5 Actions Before Governmental Authorities. There are no actions, suits or
proceedings at law or in equity or by or before any governmental authority now pending or, to the knowledge of Borrower, threatened in writing against Borrower or its property, that is reasonably expected to result in a Material Adverse Effect. 

5.6 Laws. Neither Borrower nor any of its Subsidiaries is in violation of any law, rule or regulation, or in default with
respect to any judgment, writ, injunction or decree of any governmental authority, where such violation or default is reasonably expected to result in a Material Adverse Effect. Borrower is not in default in any manner under any provision of any
agreement or instrument evidencing material Indebtedness, or any other material agreement to which it is a party or by which it is bound. 

Neither Borrower nor any of its Subsidiaries is an “investment company” or a company “controlled” by an
“investment company” under the Investment Company Act of 1940, as amended. Neither Borrower nor any of its Subsidiaries is engaged as one of its important activities in extending credit for margin stock (under Regulations X, T and U of the
Federal Reserve Board of Governors). Borrower and each of its Subsidiaries has complied in all material respects with the Federal Fair Labor Standards Act. Neither Borrower nor any of its Subsidiaries is a “holding company” or an
“affiliate” of a “holding company” or a “subsidiary company” of a “holding company” as each term is defined and used in the Public Utility Holding Company Act of 2005. Neither Borrower’s nor any of its
Subsidiaries’ properties or assets has been used by Borrower or such Subsidiary or, to Borrower’s Knowledge, by previous Persons, in disposing, producing, storing, treating, or transporting any hazardous substance other than in material
compliance with applicable laws. Borrower and each of its Subsidiaries has obtained all consents, approvals and authorizations of, made all declarations or filings with, and given all notices to, all Governmental Authorities that are necessary to
continue their respective businesses as currently conducted. 
 None of Borrower, any of its Subsidiaries, or any of
Borrower’s or its Subsidiaries’ Affiliates or any of their respective agents acting or benefiting in any capacity in connection with the transactions contemplated by this Agreement is (i) in violation of any Anti-Terrorism Law,
(ii) engaging in or conspiring to engage in any transaction that evades or avoids, or has the purpose of evading or avoiding or attempts to violate, any of the prohibitions set forth in any Anti-Terrorism Law, or (iii) is a Blocked Person.
None of Borrower, any of its Subsidiaries, or to the knowledge of Borrower and any of their Affiliates or agents, acting or benefiting in any capacity in connection with the transactions contemplated by this Agreement, (x) conducts any business
or engages in making or receiving any contribution of funds, goods or services to or for the benefit of any Blocked Person, or (y) deals in, or otherwise engages in any transaction relating to, any property or interest in property blocked
pursuant to Executive Order No. 13224, any similar executive order or other Anti-Terrorism Law. None of the funds to be provided under this Agreement will be used, directly or indirectly, (a) for any activities in violation of any
applicable anti-money laundering, economic sanctions and anti-bribery laws and 

  
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regulations laws and regulations or (b) for any payment to any governmental official or employee, political party, official of a political party, candidate for political office, or anyone
else acting in an official capacity, in order to obtain, retain or direct business or obtain any improper advantage, in violation of the United States Foreign Corrupt Practices Act of 1977, as amended. 

5.7 Information Correct and Current. No information, report, Advance Request, financial statement, exhibit or schedule
furnished, by or on behalf of Borrower to Agent in connection with any Loan Document or included therein or delivered pursuant thereto contained, or, when taken as a whole, contains or will contain any material misstatement of fact or, when taken
together with all other such information or documents, omitted, omits or will omit to state any material fact necessary to make the statements therein, in the light of the circumstances under which they were, are or will be made, not materially
misleading at the time such statement was made or deemed made. Additionally, any and all financial or business projections provided by Borrower to Agent, whether prior to or after the Closing Date, shall be (i) provided in good faith and based
on the most current data and information available to Borrower, and (ii) the most current of such projections provided to Borrower’s Board of Directors (it being understood that such projections are subject to significant uncertainties and
contingencies, many of which are beyond the control of Borrower, that no assurance is given that any particular projections will be realized, and that actual results may differ). 

5.8 Tax Matters. Except as described on Schedule 5.8 and except those being contested in good faith with adequate reserves
under GAAP, (a) Borrower has filed all material federal, state and local tax returns that it is required to file, (b) Borrower has duly paid or fully reserved for all taxes or installments thereof (including any interest or penalties) as
and when due, which have or may become due pursuant to such returns, and (c) Borrower has paid or fully reserved for any tax assessment received by Borrower for the three (3) years preceding the Closing Date, if any (including any taxes
being contested in good faith and by appropriate proceedings), in each case, other than with respect to taxes that do not exceed, individually or in the aggregate, $25,000. 

5.9 Intellectual Property Claims. Borrower is the sole owner of, or otherwise has the right to use, the Intellectual Property
material to Borrower’s business. Except as described on Schedule 5.9, (i) each of the material Copyrights, Trademarks and Patents is valid and enforceable, (ii) no material part of the Intellectual Property has been judged invalid or
unenforceable, in whole or in part, and (iii) no claim has been made to Borrower that any material part of the Intellectual Property violates the rights of any third party. Exhibit D is a true, correct and complete list of each of
Borrower’s Patents, registered Trademarks, registered Copyrights, and material agreements under which Borrower licenses Intellectual Property from third parties (other than shrink-wrap software licenses), together with application or
registration numbers, as applicable, owned by Borrower or any Subsidiary, in each case as of the Closing Date. Borrower is not in material breach of, nor has Borrower failed to perform any material obligations under, any of the foregoing contracts,
licenses or agreements and, to Borrower’s knowledge, no third party to any such contract, license or agreement is in material breach thereof or has failed to perform any material obligations thereunder. 

  
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 5.10 Intellectual Property. Except as described on Schedule 5.10, Borrower
has all material rights with respect to Intellectual Property that it uses in, and that is necessary or material in the operation or conduct of Borrower’s business as currently conducted and proposed to be conducted by Borrower. Without
limiting the generality of the foregoing, and in the case of Licenses, except for restrictions that are unenforceable under Division 9 of the UCC, Borrower has the right, to the extent required to operate Borrower’s business, to freely
transfer, license or assign Intellectual Property necessary or material in the operation or conduct of Borrower’s business as currently conducted by Borrower, without condition, restriction or payment of any kind (other than license payments in
the ordinary course of business) to any third party, and Borrower owns or has the right to use, pursuant to valid licenses, all software development tools, library functions, compilers and all other third-party software and other items that are
material to Borrower’s business and used in the design, development, promotion, sale, license, manufacture, import, export, use or distribution of Borrower Products that are material to Borrower’s business except customary covenants in
inbound license agreements and equipment leases where Borrower is the licensee or lessee. 
 5.11 Borrower Products. Except
as described on Schedule 5.11, which may be updated by Borrower in a written notice provided after the Closing Date, no Intellectual Property owned by Borrower or Borrower Product has been or is subject to any actual or, to the knowledge of
Borrower, threatened in writing litigation, proceeding (including any proceeding in the United States Patent and Trademark Office or any corresponding foreign office or agency) or outstanding decree, order, judgment, settlement agreement or
stipulation that restricts in any manner Borrower’s use, transfer or licensing thereof or that may affect the validity, use or enforceability thereof, in such case, which could reasonably be expected to have a Material Adverse Effect. There is
no decree, order, judgment, agreement, stipulation, arbitral award or other provision entered into in connection with any litigation or proceeding that obligates Borrower to grant licenses or ownership interest in any future Intellectual Property
related to the operation or conduct of the business of Borrower or Borrower Products. Except as set forth on Schedule 5.11, Borrower has not received any written notice or claim, challenging or questioning Borrower’s ownership in any
Intellectual Property material to Borrower’s business (or written notice of any claim challenging or questioning the ownership in any licensed Intellectual Property of the owner thereof) or suggesting that any third party has any claim of legal
or beneficial ownership with respect thereto nor, to Borrower’s knowledge, is there a reasonable basis for any such claim. Neither Borrower’s use of its Intellectual Property material to Borrower’s business nor the production and sale
of Borrower Products material to Borrower’s business infringes the Intellectual Property or other rights of others. 

5.12 Financial Accounts. Exhibit E, as may be updated by the Borrower in a written notice provided to Agent after the Closing
Date, is a true, correct and complete list of (a) all banks and other financial institutions at which Borrower or any Subsidiary maintains Deposit Accounts and (b) all institutions at which Borrower or any Subsidiary maintains an account
holding Investment Property, and such exhibit correctly identifies the name, address and telephone number of each bank or other institution, the name in which the account is held, a description of the purpose of the account, and the complete account
number therefor. 

  
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 5.13 Employee Loans. Except as described on Schedule 5.13, which may be
updated by Borrower in a written notice provided after the Closing Date, Borrower has no outstanding loans to any employee, officer or director of the Borrower nor has Borrower guaranteed the payment of any loan made to an employee, officer or
director of the Borrower by a third party. 
 5.14 Capitalization and Subsidiaries. Borrower’s capitalization as of the
Closing Date is set forth on Schedule 5.14 annexed hereto. Borrower does not own any stock, partnership interest or other securities of any Person, except for Permitted Investments. Attached as Schedule 5.14, as may be updated by Borrower in a
written notice provided after the Closing Date, is a true, correct and complete list of each Subsidiary. 
 5.15 Foreign
Subsidiary Voting Rights. No decision or action in any governing document of any Foreign Subsidiary (other than an Eligible Foreign Subsidiary) requires a vote of greater than 50.1% of the Equity Interests or voting rights of such Foreign
Subsidiary. 
 SECTION 6 INSURANCE; INDEMNIFICATION 

6.1 Coverage. Borrower shall cause to be carried and maintained commercial general liability insurance, on an occurrence form,
against risks customarily insured against in Borrower’s line of business. Such risks shall include the risks of bodily injury, including death, property damage, personal injury, advertising injury, and contractual liability per the terms of the
indemnification agreement found in Section 6.3. Borrower must maintain a minimum of $2,000,000 of commercial general liability insurance for each occurrence. Borrower has and agrees to maintain a minimum of $2,000,000 of directors’ and
officers’ insurance for each occurrence and $5,000,000 in the aggregate. So long as there are any Secured Obligations outstanding (other than inchoate indemnity obligations and other obligations which are expressly stated to survive termination
of this Agreement), Borrower shall also cause to be carried and maintained insurance upon the Collateral, insuring against all risks of physical loss or damage howsoever caused, in an amount not less than the full replacement cost of the Collateral,
provided that such insurance may be subject to standard exceptions and deductibles. 
 6.2 Certificates. Borrower shall
deliver to Agent certificates of insurance that evidence Borrower’s compliance with its insurance obligations in Section 6.1 and the obligations contained in this Section 6.2. Borrower’s insurance certificate shall state Agent
(shown as “Hercules Capital, Inc.”, as Agent”) is an additional insured for commercial general liability, a loss payee for all risk property damage insurance, subject to the insurer’s approval, and a loss payee for property
insurance and additional insured for liability insurance for any future insurance that Borrower may acquire from such insurer. Attached to the certificates of insurance will be additional insured endorsements for liability and lender’s loss
payable endorsements for all risk property damage 

  
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insurance. All certificates of insurance will provide for a minimum of thirty (30) days advance written notice to Agent of cancellation (other than cancellation for non-payment of premiums, for which ten (10) days’ advance written notice shall be sufficient) or any other change adverse to Agent’s interests. Any failure of Agent to scrutinize such insurance
certificates for compliance is not a waiver of any of Agent’s rights, all of which are reserved. Borrower shall provide Agent with copies of each insurance policy within thirty (30) days of the Closing Date, and upon entering or amending
any insurance policy required hereunder, Borrower shall provide Agent with copies of such policies and shall promptly deliver to Agent updated insurance certificates with respect to such policies. 

6.3 Indemnity. Borrower agrees to indemnify and hold Agent, Lender and their officers, directors, employees, agents, in-house attorneys, representatives and shareholders (each, an “Indemnified Person”) harmless from and against any and all claims, costs, expenses, damages and liabilities (including such claims, costs,
expenses, damages and liabilities based on liability in tort, including strict liability in tort), including reasonable attorneys’ fees and disbursements and other costs of investigation or defense (including those incurred upon any appeal)
(collectively, “Liabilities”), that may be instituted or asserted against or incurred by such Indemnified Person as the result of credit having been extended, suspended or terminated under this Agreement and the other Loan Documents or the
administration of such credit, or in connection with or arising out of the transactions contemplated hereunder and thereunder, or any actions or failures to act in connection therewith, or arising out of the disposition or utilization of the
Collateral, excluding in all cases Liabilities to the extent resulting solely from any Indemnified Person’s gross negligence or willful misconduct. Borrower agrees to pay, and to save Agent and Lender harmless from, any and all liabilities with
respect to, or resulting from any delay in paying, any and all excise, sales or other similar taxes (excluding taxes imposed on or measured by the net income of Agent or Lender) that may be payable or determined to be payable with respect to any of
the Collateral or this Agreement. In no event shall any Indemnified Person be liable on any theory of liability for any special, indirect, consequential or punitive damages (including any loss of profits, business or anticipated savings). This
Section 6.3 shall survive the repayment of indebtedness under, and otherwise shall survive the expiration or other termination of, the Loan Agreement. 

SECTION 7 COVENANTS OF BORROWER 

Borrower agrees as follows: 

7.1 Financial Reports. Borrower shall furnish to Agent the financial statements and reports listed hereinafter (the
“Financial Statements”): 
 (a) as soon as practicable (and in any event within 30 days) after the end of each
month, unaudited interim and year-to-date financial statements as of the end of such month (prepared on a consolidated and consolidating basis, if applicable), including
balance sheet and related statements of income and cash flows accompanied by a report detailing any material contingencies (including the commencement of any material litigation by or against Borrower) or any other occurrence that could reasonably
be 

  
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expected to have a Material Adverse Effect, prepared in accordance with GAAP, except (i) for the absence of footnotes, (ii) that they are subject to normal year end adjustments, and
(iii) they do not contain certain non-cash items that are customarily included in quarterly and annual financial statements; 

(b) as soon as practicable (and in any event within 45 days) after the end of each calendar quarter, unaudited interim and year-to-date financial statements as of the end of such calendar quarter (prepared on a consolidated and consolidating basis, if applicable), including balance sheet and
related statements of income and cash flows accompanied by a report detailing any material contingencies (including the commencement of any material litigation by or against Borrower) or any other occurrence that could reasonably be expected to have
a Material Adverse Effect, certified by Borrower’s Chief Executive Officer or Chief Financial Officer to the effect that they have been prepared in accordance with GAAP, except (i) for the absence of footnotes, and (ii) that they are
subject to normal year end adjustments; as well as the most recent capitalization table for Borrower, including the weighted average exercise price of employee stock options; 

(c) as soon as practicable (and in any event within one hundred eighty (180) days) after the end of each fiscal year,
unqualified audited financial statements as of the end of such year (prepared on a consolidated and consolidating basis, if applicable), including balance sheet and related statements of income and cash flows, and setting forth in comparative form
the corresponding figures for the preceding fiscal year, certified by a firm of independent certified public accountants selected by Borrower and reasonably acceptable to Agent, accompanied by any management report from such accountants (Agent
hereby acknowledges that PwC is an acceptable firm of independent public accounts); 
 (d) as soon as practicable (and in any
event within 30 days) after the end of each month, a Compliance Certificate in the form of Exhibit F; 
 (e) as soon as
practicable (and in any event within 30 days) after the end of each month, a report showing agings of accounts receivable and accounts payable; 

(f) promptly and in any event within 5 days after the sending or filing thereof, as the case may be, copies of any proxy
statements, financial statements or reports that Borrower has made generally available to holders of its Preferred Stock and copies of any regular, periodic and special reports or registration statements that Borrower files with the Securities and
Exchange Commission or any governmental authority that may be substituted therefor, or any national securities exchange; 

(g) at the same time and in the same manner as it gives to its Board of Directors, copies of all board packages that Borrower
provides to its directors in connection with meetings of the Board of Directors, and within 30 days after each such meeting, minutes of such meeting, provided that in all cases Borrower may exclude confidential compensation information, information
presenting a conflict of interest with Agent or Lender and information covered by attorney-client privilege; 

  
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 (h) any budget and any forecast of Borrower promptly following its approval
by Borrower’s Board of Directors, and in any event, not less than once annually, no later than 60 days following the end of the fiscal year; 

(i) such other financial information reasonably requested by Agent; and 

(j) immediate notice if Borrower or any Subsidiary has knowledge that Borrower, or any Subsidiary or Affiliate of Borrower, is
listed on the OFAC Lists or (a) is convicted on, (b) pleads nolo contendere to, (c) is indicted on, or (d) is arraigned and held over on charges involving money laundering or predicate crimes to money laundering. 

Borrower shall not (without the consent of Agent, such consent not to be unreasonably withheld or delayed), make any change in its (a) accounting
policies or reporting practices, except as required by GAAP or (b) fiscal years or fiscal quarters. As of the Closing Date, the fiscal year of Borrower ends on December 31. 

The executed Compliance Certificate may be sent via email to Agent at legal@herculestech.com. All Financial Statements required to be delivered pursuant to
clauses (a), (b) and (c) shall be sent via e-mail to financialstatements@herculestech.com with a copy to legal@herculestech.com provided, that if e-mail is not
available or sending such Financial Statements via e-mail is not possible, they shall be faxed to Agent at: (650) 473-9194, attention Account Manager: X4
Pharmaceuticals, Inc. 
 Notwithstanding the foregoing, documents required to be delivered pursuant to the terms hereof (to the extent any such documents
are included in materials otherwise filed with the SEC) may be delivered electronically and if so delivered, shall be deemed to have been delivered on the date on which Borrower emails a link thereto to Agent. 

7.2 Management Rights. Borrower shall permit any representative that Agent or Lender authorizes, including its attorneys and
accountants, to inspect the Collateral and examine and make copies and abstracts of the books of account and records of Borrower at reasonable times and upon reasonable notice during normal business hours; provided, however, that so long as no Event
of Default has occurred and is continuing, such examinations shall be limited to no more often than twice per fiscal year. In addition, any such representative shall have the right to meet with management and officers of Borrower to discuss such
books of account and records at reasonable times and upon reasonable notice during normal business hours. In addition, Agent or Lender shall be entitled at reasonable times and intervals to consult with and advise the management and officers of
Borrower concerning significant business issues affecting Borrower; provided that management and officers of Borrower shall not be bound to accept such advisement. Such consultations shall not unreasonably interfere with Borrower’s business
operations. The parties intend that the rights granted Agent and Lender shall constitute “management rights” within the meaning of 29 C.F.R. Section 2510.3-101(d)(3)(ii), but that any advice,
recommendations or participation by Agent or Lender with respect to any business issues shall not be deemed to give Agent or Lender, nor be deemed an exercise by Agent or Lender of, control over Borrower’s management or policies. 

  
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 7.3 Further Assurances. Borrower shall from time to time following
Agent’s request execute, deliver and file, alone or with Agent, any financing statements, security agreements, collateral assignments, notices, control agreements, or other documents to perfect or give the highest priority to Agent’s Lien
on the Collateral. Borrower shall from time to time procure any instruments or documents as may be reasonably requested by Agent, and take all further action that may be necessary, or that Agent may reasonably request, to perfect and protect the
Liens granted hereby and thereby. In addition, and for such purposes only, Borrower hereby authorizes Agent to execute and deliver on behalf of Borrower and to file such financing statements (including an indication that the financing statement
covers “all assets or all personal property” of Borrower in accordance with Section 9-504 of the UCC), collateral assignments, notices, control agreements, security agreements and other
documents without the signature of Borrower either in Agent’s name or in the name of Agent as agent and attorney-in-fact for Borrower. Borrower shall protect and
defend Borrower’s title to the Collateral and Agent’s Lien thereon against all Persons claiming any interest adverse to Borrower or Agent other than Permitted Liens. 

7.4 Indebtedness. Borrower shall not create, incur, assume, guarantee or be or remain liable with respect to any Indebtedness,
or permit any Subsidiary so to do, other than Permitted Indebtedness, or prepay any Indebtedness or take any actions which impose on Borrower an obligation to prepay any Indebtedness, except for (a) the conversion of Indebtedness into equity
securities and the payment of cash in lieu of fractional shares in connection with such conversion, (b) purchase money Indebtedness pursuant to its then applicable payment schedule, (c) prepayment by any Subsidiary of
(i) inter-company Indebtedness owed by such Subsidiary to any Borrower, or (ii) if such Subsidiary is not a Borrower, intercompany Indebtedness owed by such Subsidiary to another Subsidiary that is not a Borrower or (d) as otherwise
permitted hereunder or approved in writing by Agent. 
 7.5 Collateral. Borrower shall at all times keep the Collateral, the
Intellectual Property and all other property and assets used in Borrower’s business or in which Borrower now or hereafter holds any interest free and clear from any legal process or Liens whatsoever (except for Permitted Liens), and shall give
Agent prompt written notice of any legal process affecting the Collateral, the Intellectual Property, such other property and assets, or any Liens thereon, provided however, that the Collateral and such other property and assets may be subject to
Permitted Liens except that there shall be no Liens whatsoever on Intellectual Property other than (i) customary restrictions on assignment, sublicense or transfer that may exist in any license agreement where Borrower or a Subsidiary is the
licensee (and not the licensor) and (ii) licenses of Intellectual Property that constitute Permitted Transfers. Borrower shall not agree with any Person other than Agent or Lender not to encumber its property other than pursuant to customary
restrictions in leases, licenses and agreements in respect of Permitted Indebtedness. Borrower shall not enter into or suffer to exist or become effective any agreement that prohibits or limits the ability of any Borrower to create, incur, assume or
suffer to exist any Lien upon any of its Intellectual Property, whether now owned or hereafter acquired, to secure its obligations under the Loan Documents to which it is a party other than (a) this Agreement and the other Loan Documents,
(b) any agreements 

  
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governing any purchase money Liens or capital lease obligations otherwise permitted hereby (in which case, any prohibition or limitation shall only be effective against the assets financed
thereby) and (c) customary restrictions on the assignment of leases, licenses and other agreements. Borrower shall cause its Subsidiaries to protect and defend such Subsidiary’s title to its assets from and against all Persons claiming any
interest adverse to such Subsidiary, and Borrower shall cause its Subsidiaries at all times to keep such Subsidiary’s property and assets free and clear from any legal process or Liens whatsoever (except for Permitted Liens, provided however,
that there shall be no Liens whatsoever on Intellectual Property other than (i) customary restrictions on assignment, sublicense or transfer that may exist in any license agreement where Borrower or a Subsidiary is the licensee (and not the
licensor) and (ii) licenses of Intellectual Property that constitute Permitted Transfers), and shall give Agent prompt written notice of any legal process affecting such Subsidiary’s assets. 

7.6 Investments. Borrower shall not directly or indirectly acquire or own, or make any Investment in or to any Person, or
permit any of its Subsidiaries so to do, other than Permitted Investments. 
 7.7 Distributions. Borrower shall not, and
shall not allow any Subsidiary to, (a) repurchase or redeem any class of stock or other Equity Interest other than pursuant to employee, director or consultant repurchase plans or other similar agreements, provided, however, in each case the
repurchase or redemption price does not exceed the original consideration paid for such stock or Equity Interest, or (b) declare or pay any cash dividend or make a cash distribution on any class of stock or other Equity Interest, except that a
Subsidiary may pay dividends or make distributions to Borrower, or (c) lend money to any employees, officers or directors (except for Permitted Investments) or guarantee the payment of any such loans granted by a third party in excess of
$100,000 in the aggregate or (d) waive, release or forgive any Indebtedness owed by any employees, officers or directors in excess of $100,000 in the aggregate. 

7.8 Transfers. Except for Permitted Transfers, Borrower shall not, and shall not allow any Subsidiary to, voluntarily or
involuntarily transfer, sell, lease, license, lend or in any other manner convey any equitable, beneficial or legal interest in any material portion of its assets. 

7.9 Mergers or Acquisitions. Borrower shall not merge or consolidate, or permit any of its Subsidiaries to merge or
consolidate, with or into any other business organization (other than mergers or consolidations of (a) a Subsidiary which is not a Borrower into another Subsidiary or into Borrower or (b) a Borrower into another Borrower), or acquire, or
permit any of its Subsidiaries to acquire, all or substantially all of the capital stock or property of another Person. 

7.10 Taxes. Borrower and its Subsidiaries shall pay when due all material taxes, fees or other charges of any nature whatsoever
(together with any related interest or penalties) now or hereafter imposed or assessed against Borrower, Agent, Lender or the Collateral or upon Borrower’s ownership, possession, use, operation or disposition thereof or upon Borrower’s
rents, receipts or earnings arising therefrom. Borrower shall file on or before the due date therefor all personal property tax returns in respect of the Collateral. Notwithstanding the foregoing, Borrower may contest, in good faith and by
appropriate proceedings, taxes for which Borrower maintains adequate reserves therefor in accordance with GAAP. 

  
 28 

 7.11 Corporate Changes. Neither Borrower nor any Subsidiary shall change its
corporate name, legal form or jurisdiction of formation without twenty (20) days’ prior written notice to Agent. Neither Borrower nor any Subsidiary shall suffer a Change in Control. Neither Borrower nor any Subsidiary shall relocate its
chief executive office or its principal place of business unless: (i) it has provided prior written notice to Agent; and (ii) such relocation shall be within the continental United States of America. Neither Borrower nor any Qualified
Subsidiary shall relocate any item of Collateral (other than (x) sales of Inventory in the ordinary course of business, (y) relocations of Equipment having an aggregate value of up to $150,000 in any fiscal year, and (z) relocations
of Collateral from a location described on Exhibit C to another location described on Exhibit C) unless (i) it has provided prompt written notice to Agent, (ii) such relocation is within the continental United States of America and,
(iii) if such relocation is to a third party bailee, it has delivered a bailee agreement in form and substance reasonably acceptable to Agent. 

7.12 Deposit Accounts. Neither Borrower nor any Qualified Subsidiary shall maintain any Deposit Accounts, or accounts holding
Investment Property, except (i) for Excluded Accounts, or (ii) with respect to which Agent has an Account Control Agreement. 

7.13 Borrower shall notify Agent of each Subsidiary formed subsequent to the Closing Date and, within 15 days of formation,
shall cause any such Qualified Subsidiary to execute and deliver to Agent a Joinder Agreement. 
 7.14 [Reserved.] 

7.15 Notification of Event of Default. Borrower shall notify Agent immediately of the occurrence of any Event of Default. 

7.16 Agent and Lender have received a license from the U.S. Small Business Administration (“SBA”) to extend loans as
a small business investment company (“SBIC”) pursuant to the Small Business Investment Act of 1958, as amended, and the associated regulations (collectively, the “SBIC Act”). Portions of the loan to Borrower will be made under
the SBA license and the SBIC Act. Addendum 1 to this Agreement outlines various responsibilities of Agent, Lender and Borrower associated with an SBA loan, and such Addendum 1 is hereby incorporated in this Agreement. 

7.17 Use of Proceeds. Borrower agrees that the proceeds of the Loans shall be used solely to refinance existing indebtedness,
to pay related fees and expenses in connection with this Agreement and for working capital and general corporate purposes. The proceeds of the Loans will not be used in violation of Anti-Corruption Laws or applicable Sanctions. 

  
 29 

 7.18 Foreign Subsidiary Voting Rights. Borrower shall not, and shall not
permit any Subsidiary, to amend or modify any governing document of any Foreign Subsidiary of Borrower (other than an Eligible Foreign Subsidiary) the effect of which is to require a vote of greater than 50.1% of the Equity Interests or voting
rights of such entity for any decision or action of such entity. 
 7.19 Compliance with Laws. 

Borrower shall maintain, and shall cause its Subsidiaries to maintain, compliance in all material respect with all applicable laws, rules or
regulations (including any law, rule or regulation with respect to the making or brokering of loans or financial accommodations), and shall, or cause its Subsidiaries to, obtain and maintain all required governmental authorizations, approvals,
licenses, franchises, permits or registrations reasonably necessary in connection with the conduct of Borrower’s business. 
 Neither
Borrower nor any of its Subsidiaries shall, nor shall Borrower or any of its Subsidiaries permit any Affiliate controlled by Borrower or any Subsidiary to, directly or indirectly, knowingly enter into any documents, instruments, agreements or
contracts with any Person listed on the OFAC Lists. Neither Borrower nor any of its Subsidiaries shall, nor shall Borrower or any of its Subsidiaries, permit any Affiliate controlled by Borrower or any Subsidiary to, directly or indirectly,
(i) conduct any business or engage in any transaction or dealing with any Blocked Person, including, without limitation, the making or receiving of any contribution of funds, goods or services to or for the benefit of any Blocked Person,
(ii) deal in, or otherwise engage in any transaction relating to, any property or interests in property blocked pursuant to Executive Order No. 13224 or any similar executive order or other Anti-Terrorism Law, or (iii) engage in or
conspire to engage in any transaction that evades or avoids, or has the purpose of evading or avoiding, or attempts to violate, any of the prohibitions set forth in Executive Order No. 13224 or other Anti-Terrorism Law. 

Borrower and its Subsidiaries and their respective officers and employees and to the knowledge of Borrower, its directors and agents, are in
compliance with Anti-Corruption Laws and applicable Sanctions in all material respects. 
 None of Borrower, any of its Subsidiaries or any
of their respective directors, officers or employees, or to the knowledge of Borrower, any agent for Borrower or its Subsidiaries that will act in any capacity in connection with or benefit from the credit facility established hereby, is a
Sanctioned Person. No Loan, use of proceeds or other transaction contemplated by this Agreement will violate Anti-Corruption Laws or applicable Sanctions. 

7.20 Intellectual Property. Each Borrower shall protect, defend and maintain the validity and enforceability of its
Intellectual Property material to its business; (ii) promptly advise Agent in writing of material infringements of its Intellectual Property; and (iii) not allow any Intellectual Property material to Borrowers’ business to be
abandoned, forfeited or dedicated to the public without Agent’s written consent. If a Borrower (i) obtains any Patent, registered Trademark, registered Copyright, registered mask work, or any pending application for any of the foregoing,
whether as owner, licensee or otherwise, or (ii) applies for any Patent or the registration of any Trademark, 

  
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then such Borrower shall promptly, and in any event, within thirty (30) days thereof, provide written notice thereof to Agent and shall execute such intellectual property security agreements
and other documents and take such other actions as Agent may request in its good faith business judgment to perfect and maintain a first priority perfected security interest in favor of Agent in such property. If a Borrower decides to register any
Copyrights or mask works in the United States Copyright Office, such Borrower shall: (x) provide Agent with at least fifteen (15) days prior written notice of such Borrower’s intent to register such Copyrights or mask works together
with a copy of the application it intends to file with the United States Copyright Office (excluding exhibits thereto); (y) execute an intellectual property security agreement and such other documents and take such other actions as Agent may request
in its good faith business judgment to perfect and maintain a first priority perfected security interest in favor of Agent in the Copyrights or mask works intended to be registered with the United States Copyright Office; and (z) record such
intellectual property security agreement with the United States Copyright Office contemporaneously with filing the Copyright or mask work application(s) with the United States Copyright Office. Borrowers shall promptly provide to Agent copies of all
applications that it files for Patents or for the registration of Trademarks, Copyrights or mask works, together with evidence of the recording of the intellectual property security agreement required for Agent to perfect and maintain a first
priority perfected security interest in such property. 
 7.21 Transactions with Affiliates. Borrower shall not and shall not
permit any Subsidiary to, directly or indirectly, enter into or permit to exist any transaction of any kind with any Affiliate of Borrower or such Subsidiary on terms that are less favorable to Borrower or such Subsidiary, as the case may be, than
those that might be obtained in an arm’s length transaction from a Person who is not an Affiliate of Borrower or such Subsidiary. 

7.22 Minimum Cash. Borrower at all times shall maintain Cash in an account or accounts of X4 Pharmaceuticals, Inc. subject to
an Account Control Agreement, in an aggregate amount greater than or equal to the lesser of: (i) 125% of the aggregate Term Loan Advances outstanding under this Agreement; and (ii) 100% of Borrower’s Cash reserves. 

7.23 Post-Closing Items. On or before the corresponding dates set forth on Schedule 7.23, Borrower shall use its commercially
reasonable efforts to deliver or cause to be delivered or completed the items listed on Schedule 7.23. 
 SECTION 8 RIGHT TO INVEST

 8.1 Lender or its assignee or nominee shall have the right, in its discretion, to participate, in a cumulative amount
of up to $1,000,000, in one or more Subsequent Financings, on the same terms, conditions and pricing afforded to others participating in any such Subsequent Financing, provided, however, Lender may not participate in any “Exempted
Issuances,” as such term is defined in the Charter. This Section 8.1, and all rights and obligations hereunder, shall survive the repayment of indebtedness under, and otherwise shall survive the expiration or other termination of, the Loan
Agreement, but shall terminate upon the earliest to occur of: (a) the Initial Public Offering, (b) the date Borrower becomes subject to the reporting obligations of the Securities and Exchange Act of 1934, and (c) a “Deemed
Liquidation Event,” as such term is defined in the Charter. 

  
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 SECTION 9 EVENTS OF DEFAULT 

The occurrence of any one or more of the following events shall be an Event of Default: 

9.1 Payments. Borrower fails to pay any amount due under this Agreement or any of the other Loan Documents on the due date;
provided, however, that an Event of Default shall not occur on account of a failure to pay due solely to an administrative or operational error of Agent or Lender or Borrower’s bank if Borrower had the funds to make the payment when due and
makes the payment within three (3) Business Days following Borrower’s knowledge of such failure to pay; or 
 9.2
Covenants. Borrower breaches or defaults in the performance of any covenant or Secured Obligation under this Agreement, or any of the other Loan Documents or any other agreement among Borrower, Agent and Lender, and (a) with respect to a
default under any covenant under this Agreement (other than under Sections 6, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 7.15, 7.16, 7.17, 7.18, 7.19, 7.20 and 7.22) any other Loan Document or any other agreement among Borrower, Agent and Lender, such default
continues for more than ten (10) Business Days after the earlier of the date on which (i) Agent or Lender has given notice of such default to Borrower and (ii) Borrower has actual knowledge of such default or (b) with respect to
a default under any of Sections 6, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 7.15, 7.16, 7.17, 7.18, 7.19, 7.20 and 7.22, the occurrence of such default; or 

9.3 Material Adverse Effect. A circumstance has occurred that could reasonably be expected to have a Material Adverse Effect;
or 
 9.4 Representations. Any representation or warranty made by Borrower in any Loan Document or in the Warrant shall have
been false or misleading in any material respect when made or when deemed made; or 
 9.5 Insolvency. Borrower (A) (i)
shall make an assignment for the benefit of creditors; or (ii) shall be unable to pay its debts as they become due, or be unable to pay or perform under the Loan Documents, or shall become insolvent; or (iii) shall file a voluntary
petition in bankruptcy; or (iv) shall file any petition, answer, or document seeking for itself any reorganization, arrangement, composition, readjustment, liquidation, dissolution or similar relief under any present or future statute, law or
regulation pertinent to such circumstances; or (v) shall seek or consent to or acquiesce in the appointment of any trustee, receiver, or liquidator of Borrower or of all or any substantial part (i.e., 33¬1/3% or more) of the assets or
property of Borrower; or (vi) shall cease operations of its business as its business has normally been conducted, or terminate substantially all of its employees; or (vii) Borrower or its directors or majority shareholders shall take any
action initiating any of the foregoing actions described in 

  
 32 

 
clauses (i) through (vi); or (B) either (i) forty-five (45) days shall have expired after the commencement of an involuntary action against Borrower seeking reorganization,
arrangement, composition, readjustment, liquidation, dissolution or similar relief under any present or future statute, law or regulation, without such action being dismissed or all orders or proceedings thereunder affecting the operations or the
business of Borrower being stayed; or (ii) a stay of any such order or proceedings shall thereafter be set aside and the action setting it aside shall not be timely appealed; or (iii) Borrower shall file any answer admitting or not
contesting the material allegations of a petition filed against Borrower in any such proceedings; or (iv) the court in which such proceedings are pending shall enter a decree or order granting the relief sought in any such proceedings; or
(v) forty-five (45) days shall have expired after the appointment, without the consent or acquiescence of Borrower, of any trustee, receiver or liquidator of Borrower or of all or any substantial part of the properties of Borrower without
such appointment being vacated; or 
 9.6 Attachments; Judgments. Any portion of Borrower’s assets is attached or
seized, or a levy is filed against any such assets, or a judgment or judgments is/are entered for the payment of money (not covered by independent third party insurance as to which liability has not been rejected by such insurance carrier),
individually or in the aggregate, of at least $250,000, or Borrower is enjoined or in any way prevented by court order from conducting any part of its business and such attachment, seizure, levy, judgment or enjoinment is not, within thirty
(30) days after the occurrence thereof, discharged or stayed (whether through the posting of a bond or otherwise); or 

9.7 Other Obligations. The occurrence of any “event of default” under any agreement or obligation of Borrower
involving any Indebtedness in excess of $250,000 after giving effect to any applicable grace period thereunder which results in a right by such third party to accelerate the maturity of such Indebtedness. 

SECTION 10 REMEDIES  

10.1 General. Upon and during the continuance of any one or more Events of Default, (i) Agent may, and at the direction
of the Required Lenders shall, accelerate and demand payment of all or any part of the Secured Obligations together with a Prepayment Charge and declare them to be immediately due and payable (provided, that upon the occurrence of an Event of
Default of the type described in Section 9.5, all of the Secured Obligations shall automatically be accelerated and made due and payable, in each case without any further notice or act), (ii) Agent may, at its option, sign and file in
Borrower’s name any and all collateral assignments, notices, control agreements, security agreements and other documents it deems necessary or appropriate to perfect or protect the repayment of the Secured Obligations, and in furtherance
thereof, Borrower hereby grants Agent an irrevocable power of attorney coupled with an interest during the continuance of such Event of Default, and (iii) Agent may notify any of Borrower’s account debtors to make payment directly to
Agent, compromise the amount of any such account on Borrower’s behalf and endorse Agent’s name without recourse on any such payment for deposit directly to Agent’s account. Agent may, and at the direction of the Required Lenders
shall, exercise all rights and remedies with respect to the Collateral 

  
 33 

 
under the Loan Documents or otherwise available to it under the UCC and other applicable law, including the right to release, hold, sell, lease, liquidate, collect, realize upon, or otherwise
dispose of all or any part of the Collateral and the right to occupy, utilize, process and commingle the Collateral. All Agent’s rights and remedies shall be cumulative and not exclusive. 

10.2 Collection; Foreclosure. Upon the occurrence and during the continuance of any Event of Default, Agent may, and at the
direction of the Required Lenders shall, at any time or from time to time, apply, collect, liquidate, sell in one or more sales, lease or otherwise dispose of, any or all of the Collateral, in its then condition or following any commercially
reasonable preparation or processing, in such order as Agent may elect. Any such sale may be made either at public or private sale at its place of business or elsewhere. Borrower agrees that any such public or private sale may occur upon ten
(10) calendar days’ prior written notice to Borrower. Agent may require Borrower to assemble the Collateral and make it available to Agent at a place designated by Agent that is reasonably convenient to Agent and Borrower. The proceeds of
any sale, disposition or other realization upon all or any part of the Collateral shall be applied by Agent in the following order of priorities: 

First, to Agent and Lender in an amount sufficient to pay in full Agent’s and Lender’s reasonable costs and professionals’ and
advisors’ fees and expenses as described in Section 11.11; 
 Second, to Lender in an amount equal to the then unpaid amount of the
Secured Obligations (including principal, interest, and the Default Rate interest), in such order and priority as Agent may choose in its sole discretion; and 

Finally, after the full and final payment in Cash of all of the Secured Obligations (other than inchoate obligations), to any creditor holding
a junior Lien on the Collateral, or to Borrower or its representatives or as a court of competent jurisdiction may direct. 
 Agent shall be
deemed to have acted reasonably in the custody, preservation and disposition of any of the Collateral if it complies with the obligations of a secured party under the UCC. 

10.3 No Waiver. Agent shall be under no obligation to marshal any of the Collateral for the benefit of Borrower or any other
Person, and Borrower expressly waives all rights, if any, to require Agent to marshal any Collateral. 
 10.4 Cumulative
Remedies. The rights, powers and remedies of Agent hereunder shall be in addition to all rights, powers and remedies given by statute or rule of law and are cumulative. The exercise of any one or more of the rights, powers and remedies provided
herein shall not be construed as a waiver of or election of remedies with respect to any other rights, powers and remedies of Agent. 

  
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 SECTION 11 MISCELLANEOUS  

11.1 Severability. Whenever possible, each provision of this Agreement shall be interpreted in such manner as to be effective
and valid under applicable law, but if any provision of this Agreement shall be prohibited by or invalid under such law, such provision shall be ineffective only to the extent and duration of such prohibition or invalidity, without invalidating the
remainder of such provision or the remaining provisions of this Agreement. 
 11.2 Notice. Except as otherwise provided
herein, any notice, demand, request, consent, approval, declaration, service of process or other communication (including the delivery of Financial Statements) that is required, contemplated, or permitted under the Loan Documents or with respect to
the subject matter hereof shall be in writing, and shall be deemed to have been validly served, given, delivered, and received upon the earlier of: (i) the day of transmission by electronic mail or hand delivery or delivery by an overnight
express service or overnight mail delivery service; or (ii) the third calendar day after deposit in the United States of America mails, with proper first class postage prepaid, in each case addressed to the party to be notified as follows: 

 

	 	(a)	 If to Agent: 

HERCULES CAPITAL, INC. 
 Legal
Department 
 Attention: Chief Legal Officer and Bryan Jadot 

400 Hamilton Avenue, Suite 310 

Palo Alto, CA 94301 
 email:
legal@herculestech.com 
 Telephone: 650-289-3060 

 

	 	(b)	 If to Lender: 

HERCULES CAPITAL, INC. 
 Legal
Department 
 Attention: Chief Legal Officer and Bryan Jadot 

400 Hamilton Avenue, Suite 310 

Palo Alto, CA 94301 
 email: 

Telephone: 
  

	 	(c)	 If to Borrower: 

X4 PHARMACEUTICALS, INC. 

Attention: Adam Mostafa and Brian Bowersox 

955 Massachusetts Avenue, 4th Floor 

Boston, MA 02139 
 email: 

Telephone: 

  
 35 

 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. 

One Financial Center 
 Boston, MA
02111 
 Attention: John Cheney 

email: jcheney@mintz.com 

Telephone: 617-542-6000 

or to such other address as each party may designate for itself by like notice. 

11.3 Entire Agreement; Amendments. 

(a) This Agreement and the other Loan Documents constitute the entire agreement and understanding of the parties hereto in
respect of the subject matter hereof and thereof, and supersede and replace in their entirety any prior proposals, term sheets, non-disclosure or confidentiality agreements, letters, negotiations or other
documents or agreements, whether written or oral, with respect to the subject matter hereof or thereof (including Agent’s revised proposal letter dated September 13, 2018 and the Non-Disclosure
Agreement). 
 (b) Neither this Agreement, any other Loan Document, nor any terms hereof or thereof may be amended,
supplemented or modified except in accordance with the provisions of this Section 11.3(b). The Required Lenders and Borrower party to the relevant Loan Document may, or, with the written consent of the Required Lenders, the Agent and the
Borrower party to the relevant Loan Document may, from time to time, (i) enter into written amendments, supplements or modifications hereto and to the other Loan Documents for the purpose of adding any provisions to this Agreement or the other
Loan Documents or changing in any manner the rights of the Lenders or of the Borrower hereunder or thereunder or (ii) waive, on such terms and conditions as the Required Lenders or the Agent, as the case may be, may specify in such instrument,
any of the requirements of this Agreement or the other Loan Documents or any default or Event of Default and its consequences; provided, however, that no such waiver and no such amendment, supplement or modification shall (A) forgive the
principal amount, extend the final scheduled date of maturity of any Loan, extend the scheduled date of any amortization payment in respect of any Term Loan, or reduce the stated rate of any interest or fee payable hereunder, in each case without
the written consent of each Lender directly affected thereby; (B) eliminate or reduce the voting rights of any Lender under this Section 11.3(b) without the written consent of such Lender; (C) reduce any percentage specified in the
definition of Required Lenders, consent to the assignment or transfer by the Borrower of any of its rights and obligations under this Agreement and the other Loan Documents, release all or substantially all of the Collateral or release a Borrower
from its obligations under the Loan Documents, in each case without the written consent of all Lenders; or (D) amend, modify or waive any provision of Section 11.17 without the written consent of the Agent. Any such waiver and any such
amendment, supplement or modification shall apply equally to each Lender and shall be binding upon Borrower, the Lender, the Agent and all future holders of the Loans. 

  
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 11.4 No Strict Construction. The parties hereto have participated jointly in
the negotiation and drafting of this Agreement. In the event an ambiguity or question of intent or interpretation arises, this Agreement shall be construed as if drafted jointly by the parties hereto and no presumption or burden of proof shall arise
favoring or disfavoring any party by virtue of the authorship of any provisions of this Agreement. 
 11.5 No Waiver. The
powers conferred upon Agent and Lender by this Agreement are solely to protect its rights hereunder and under the other Loan Documents and its interest in the Collateral and shall not impose any duty upon Agent or Lender to exercise any such powers.
No omission or delay by Agent or Lender at any time to enforce any right or remedy reserved to it, or to require performance of any of the terms, covenants or provisions hereof by Borrower at any time designated, shall be a waiver of any such right
or remedy to which Agent or Lender is entitled, nor shall it in any way affect the right of Agent or Lender to enforce such provisions thereafter. 

11.6 Survival. All agreements, representations and warranties contained in this Agreement and the other Loan Documents or in
any document delivered pursuant hereto or thereto shall be for the benefit of Agent and Lender and shall survive the execution and delivery of this Agreement. Sections 6.3 and 8.1 shall survive the termination of this Agreement. 

11.7 Successors and Assigns. The provisions of this Agreement and the other Loan Documents shall inure to the benefit of and be
binding on Borrower and its permitted assigns (if any). Borrower shall not assign its obligations under this Agreement or any of the other Loan Documents without Agent’s express prior written consent, and any such attempted assignment shall be
void and of no effect. Agent and Lender may assign, transfer, or endorse its rights hereunder and under the other Loan Documents without prior notice to Borrower, and all of such rights shall inure to the benefit of Agent’s and Lender’s
successors and assigns; provided that as long as no Event of Default has occurred and is continuing, neither Agent nor any Lender may assign, transfer or endorse its rights hereunder or under the Loan Documents to any party that is a direct
competitor of Borrower (as reasonably determined by Agent), it being acknowledged that in all cases, any transfer to an Affiliate of any Lender or Agent shall be allowed. 

11.8 Governing Law. This Agreement and the other Loan Documents have been negotiated and delivered to Agent and Lender in the
State of California, and shall have been accepted by Agent and Lender in the State of California. Payment to Agent and Lender by Borrower of the Secured Obligations is due in the State of California. This Agreement and the other Loan Documents shall
be governed by, and construed and enforced in accordance with, the laws of the State of California, excluding conflict of laws principles that would cause the application of laws of any other jurisdiction. 

11.9 Consent to Jurisdiction and Venue. All judicial proceedings (to the extent that the reference requirement of
Section 11.10 is not applicable) arising in or under or related to this Agreement or any of the other Loan Documents may be brought in any state or federal court located in the State of California. By execution and delivery of this

  
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Agreement, each party hereto generally and unconditionally: (a) consents to nonexclusive personal jurisdiction in Santa Clara County, State of California; (b) waives any objection as to
jurisdiction or venue in Santa Clara County, State of California; (c) agrees not to assert any defense based on lack of jurisdiction or venue in the aforesaid courts; and (d) irrevocably agrees to be bound by any judgment rendered thereby
in connection with this Agreement or the other Loan Documents. Service of process on any party hereto in any action arising out of or relating to this Agreement shall be effective if given in accordance with the requirements for notice set forth in
Section 11.2, and shall be deemed effective and received as set forth in Section 11.2. Nothing herein shall affect the right to serve process in any other manner permitted by law or shall limit the right of either party to bring
proceedings in the courts of any other jurisdiction. 
 11.10 Mutual Waiver of Jury Trial / Judicial Reference. 

(a) Because disputes arising in connection with complex financial transactions are most quickly and economically resolved by an
experienced and expert Person and the parties wish applicable state and federal laws to apply (rather than arbitration rules), the parties desire that their disputes be resolved by a judge applying such applicable laws. EACH OF BORROWER, AGENT AND
LENDER SPECIFICALLY WAIVES ANY RIGHT IT MAY HAVE TO TRIAL BY JURY OF ANY CAUSE OF ACTION, CLAIM, CROSS-CLAIM, COUNTERCLAIM, THIRD PARTY CLAIM OR ANY OTHER CLAIM (COLLECTIVELY, “CLAIMS”) ASSERTED BY BORROWER AGAINST AGENT, LENDER OR THEIR
RESPECTIVE ASSIGNEE OR BY AGENT, LENDER OR THEIR RESPECTIVE ASSIGNEE AGAINST BORROWER. This waiver extends to all such Claims, including Claims that involve Persons other than Agent, Borrower and Lender; Claims that arise out of or are in any way
connected to the relationship among Borrower, Agent and Lender; and any Claims for damages, breach of contract, tort, specific performance, or any equitable or legal relief of any kind, arising out of this Agreement, any other Loan Document. 

(b) If the waiver of jury trial set forth in Section 11.10(a) is ineffective or unenforceable, the parties agree that all
Claims shall be resolved by reference to a private judge sitting without a jury, pursuant to Code of Civil Procedure Section 638, before a mutually acceptable referee or, if the parties cannot agree, a referee selected by the Presiding Judge of
the Santa Clara County, California. Such proceeding shall be conducted in Santa Clara County, California, with California rules of evidence and discovery applicable to such proceeding. 

(c) In the event Claims are to be resolved by judicial reference, either party may seek from a court identified in
Section 11.9, any prejudgment order, writ or other relief and have such prejudgment order, writ or other relief enforced to the fullest extent permitted by law notwithstanding that all Claims are otherwise subject to resolution by judicial
reference. 

  
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 11.11 Professional Fees. Borrower promises to pay Agent’s and
Lender’s reasonable and documented fees and expenses necessary to finalize the loan documentation, including but not limited to reasonable and documented attorneys’ fees, UCC searches, filing costs, and other miscellaneous expenses. In
addition, Borrower promises to pay any and all reasonable and documented attorneys’ and other professionals’ fees and expenses incurred by Agent and Lender after the Closing Date in connection with or related to: (a) the Loan;
(b) the administration, collection, or enforcement of the Loan; (c) the amendment or modification of the Loan Documents; (d) any waiver, consent, release, or termination under the Loan Documents; (e) the protection, preservation,
audit, field exam, sale, lease, liquidation, or disposition of Collateral or the exercise of remedies with respect to the Collateral; (f) any legal, litigation, administrative, arbitration, or out of court proceeding in connection with or
related to Borrower or the Collateral, and any appeal or review thereof; and (g) any bankruptcy, restructuring, reorganization, assignment for the benefit of creditors, workout, foreclosure, or other action related to Borrower, the Collateral,
the Loan Documents, including representing Agent or Lender in any adversary proceeding or contested matter commenced or continued by or on behalf of Borrower’s estate, and any appeal or review thereof. 

11.12 Confidentiality. Agent and Lender acknowledge that certain items of Collateral and information provided to Agent and
Lender, including items provided in connection with the Non-Disclosure Agreement, by Borrower are confidential and proprietary information of Borrower, if and to the extent such information either (x) is
marked as confidential by Borrower at the time of disclosure, or (y) should reasonably be understood to be confidential (the “Confidential Information”). Accordingly, Agent and Lender agree that any Confidential Information it may
obtain during the term of this Agreement shall not be disclosed to any other Person or entity in any manner whatsoever, in whole or in part, without the prior written consent of Borrower, except that Agent and Lender may disclose any such
information: (a) to its own directors, officers, employees, accountants, counsel and other professional advisors and to its Affiliates if Agent or Lender in its sole discretion determines that any such party should have access to such
information in connection with such party’s responsibilities in connection with the Loan or this Agreement and, provided that such recipient of such Confidential Information either (i) agrees to be bound by the confidentiality provisions
of this paragraph or (ii) is otherwise subject to confidentiality restrictions that reasonably protect against the disclosure of Confidential Information; (b) if such information is generally available to the public through no fault of
Agent or Lender; (c) if required or appropriate in any report, statement or testimony submitted to any governmental authority having or claiming to have jurisdiction over Agent or Lender; (d) if required or appropriate in response to any
summons or subpoena or in connection with any litigation, to the extent permitted or deemed advisable by Agent’s or Lender’s counsel; (e) to comply with any legal requirement or law applicable to Agent or Lender; (f) to the
extent reasonably necessary in connection with the exercise of any right or remedy under any Loan Document, including Agent’s sale, lease, or other disposition of Collateral after an Event of Default; (g) to any participant or assignee of
Agent or Lender or any prospective participant or assignee; provided, that such participant or assignee or prospective participant or assignee agrees in writing to be bound by this Section prior to disclosure; or (h) otherwise with the prior
consent of Borrower; provided, that any disclosure made in violation of this Agreement shall not affect the obligations of Borrower or any of its Affiliates or any guarantor under this Agreement or the other Loan Documents. Agent’s and
Lender’s obligations under this Section 11.12 shall supersede all of their respective obligations under the Non-Disclosure Agreement. 

  
 39 

 11.13 Assignment of Rights. Borrower acknowledges and understands that Agent
or Lender may, subject to Section 11.7, sell and assign all or part of its interest hereunder and under the Loan Documents to any Person or entity (an “Assignee”). After such assignment the term “Agent” or “Lender”
as used in the Loan Documents shall mean and include such Assignee, and such Assignee shall be vested with all rights, powers and remedies of Agent and Lender hereunder with respect to the interest so assigned; but with respect to any such interest
not so transferred, Agent and Lender shall retain all rights, powers and remedies hereby given. No such assignment by Agent or Lender shall relieve Borrower of any of its obligations hereunder. Lender agrees that in the event of any transfer by it
of the Note(s)(if any), it will endorse thereon a notation as to the portion of the principal of the Note(s), which shall have been paid at the time of such transfer and as to the date to which interest shall have been last paid thereon. 

11.14 Revival of Secured Obligations. This Agreement and the Loan Documents shall remain in full force and effect and continue
to be effective if any petition is filed by or against Borrower for liquidation or reorganization, if Borrower becomes insolvent or makes an assignment for the benefit of creditors, if a receiver or trustee is appointed for all or any significant
part of Borrower’s assets, or if any payment or transfer of Collateral is recovered from Agent or Lender. The Loan Documents and the Secured Obligations and Collateral security shall continue to be effective, or shall be revived or reinstated,
as the case may be, if at any time payment and performance of the Secured Obligations or any transfer of Collateral to Agent, or any part thereof is rescinded, avoided or avoidable, reduced in amount, or must otherwise be restored or returned by, or
is recovered from, Agent, Lender or by any obligee of the Secured Obligations, whether as a “voidable preference,” “fraudulent conveyance,” or otherwise, all as though such payment, performance, or transfer of Collateral had not
been made. In the event that any payment, or any part thereof, is rescinded, reduced, avoided, avoidable, restored, returned, or recovered, the Loan Documents and the Secured Obligations shall be deemed, without any further action or documentation,
to have been revived and reinstated except to the extent of the full, final, and indefeasible payment to Agent or Lender in Cash. 

11.15 Counterparts. This Agreement and any amendments, waivers, consents or supplements hereto may be executed in any number of
counterparts, and by different parties hereto in separate counterparts, each of which when so delivered shall be deemed an original, but all of which counterparts shall constitute but one and the same instrument. 

11.16 No Third Party Beneficiaries. No provisions of the Loan Documents are intended, nor will be interpreted, to provide or
create any third-party beneficiary rights or any other rights of any kind in any Person other than Agent, Lender and Borrower unless specifically provided otherwise herein, and, except as otherwise so provided, all provisions of the Loan Documents
will be personal and solely among Agent, the Lender and the Borrower. 

  
 40 

 11.17 Agency. 

(a) Lender hereby irrevocably appoints Hercules Capital, Inc. to act on its behalf as the Agent hereunder and under the other
Loan Documents and authorizes the Agent to take such actions on its behalf and to exercise such powers as are delegated to the Agent by the terms hereof or thereof, together with such actions and powers as are reasonably incidental thereto. 

(b) Lender agrees to indemnify the Agent in its capacity as such (to the extent not reimbursed by Borrower and without limiting
the obligation of Borrower to do so), according to its respective Term Commitment percentages (based upon the total outstanding Term Loan Commitments) in effect on the date on which indemnification is sought under this Section 11.17, from and
against any and all liabilities, obligations, losses, damages, penalties, actions, judgments, suits, costs, expenses or disbursements of any kind whatsoever that may at any time be imposed on, incurred by or asserted against the Agent in any way
relating to or arising out of, this Agreement, any of the other Loan Documents or any documents contemplated by or referred to herein or therein or the transactions contemplated hereby or thereby or any action taken or omitted by the Agent under or
in connection with any of the foregoing; The agreements in this Section shall survive the payment of the Loans and all other amounts payable hereunder. 

(c) Agent in Its Individual Capacity. The Person serving as the Agent hereunder shall have the same rights and powers in its
capacity as a Lender as any other Lender and may exercise the same as though it were not the Agent and the term “Lender” shall, unless otherwise expressly indicated or unless the context otherwise requires, include each such Person serving
as Agent hereunder in its individual capacity. 
 (d) Exculpatory Provisions. The Agent shall have no duties or obligations
except those expressly set forth herein and in the other Loan Documents. Without limiting the generality of the foregoing, the Agent shall not: 
  

	 	(i)	 be subject to any fiduciary or other implied duties, regardless of whether any default or any Event of Default
has occurred and is continuing; 

  

	 	(ii)	 have any duty to take any discretionary action or exercise any discretionary powers, except discretionary
rights and powers expressly contemplated hereby or by the other Loan Documents that the Agent is required to exercise as directed in writing by the Lender, provided that the Agent shall not be required to take any action that, in its opinion or the
opinion of its counsel, may expose the Agent to liability or that is contrary to any Loan Document or applicable law; and 

  

	 	(iii)	 except as expressly set forth herein and in the other Loan Documents, have any duty to disclose, and the Agent
shall not be liable for the failure to disclose, any information relating to the Borrower or any of its Affiliates that is communicated to or obtained by any Person serving as the Agent or any of its Affiliates in any capacity.

  
 41 

 (e) The Agent shall not be liable for any action taken or not taken by it
(i) with the consent or at the request of the Lender or as the Agent shall believe in good faith shall be necessary, under the circumstances or (ii) in the absence of its own gross negligence or willful misconduct. 

(f) The Agent shall not be responsible for or have any duty to ascertain or inquire into (i) any statement, warranty or
representation made in or in connection with this Agreement or any other Loan Document, (ii) the contents of any certificate, report or other document delivered hereunder or thereunder or in connection herewith or therewith, (iii) the
performance or observance of any of the covenants, agreements or other terms or conditions set forth herein or therein or the occurrence of any default or Event of Default, (iv) the validity, enforceability, effectiveness or genuineness of this
Agreement, any other Loan Document or any other agreement, instrument or document or (v) the satisfaction of any condition set forth in Section 4 or elsewhere herein, other than to confirm receipt of items expressly required to be
delivered to the Agent. 
 (g) Reliance by Agent. Agent may rely, and shall be fully protected in acting, or refraining to
act, upon, any resolution, statement, certificate, instrument, opinion, report, notice, request, consent, order, bond or other paper or document that it has no reason to believe to be other than genuine and to have been signed or presented by the
proper party or parties or, in the case of cables, telecopies and telexes, to have been sent by the proper party or parties. In the absence of its gross negligence or willful misconduct, Agent may conclusively rely, as to the truth of the statements
and the correctness of the opinions expressed therein, upon any certificates or opinions furnished to Agent and conforming to the requirements of the Loan Agreement or any of the other Loan Documents. Agent may consult with counsel, and any opinion
or legal advice of such counsel shall be full and complete authorization and protection in respect of any action taken, not taken or suffered by Agent hereunder or under any Loan Documents in accordance therewith. Agent shall have the right at any
time to seek instructions concerning the administration of the Collateral from any court of competent jurisdiction. Agent shall not be under any obligation to exercise any of the rights or powers granted to Agent by this Agreement, the Loan
Agreement and the other Loan Documents at the request or direction of Lenders unless Agent shall have been provided by Lender with adequate security and indemnity against the costs, expenses and liabilities that may be incurred by it in compliance
with such request or direction. 
 11.18 Publicity. None of the parties hereto nor any of its respective member businesses
and Affiliates shall, without the other parties’ prior written consent (which shall not be unreasonably withheld or delayed), publicize or use (a) the other party’s name (including a brief description of the relationship among the
parties hereto), logo or hyperlink to such other parties’ web site, separately or together, in written and oral presentations, advertising, promotional and marketing materials, client lists, public relations materials or on its web site
(together, the “ Publicity Materials”); (b) the names 

  
 42 

 
of officers of such other parties in the Publicity Materials; and (c) such other parties’ name, trademarks, servicemarks in any news or press release concerning such party; provided
however, notwithstanding anything to the contrary herein, no such consent shall be required (i) to the extent necessary to comply with the requests of any regulators, legal requirements or laws applicable to such party, pursuant to any listing
agreement with any national securities exchange (so long as such party provides prior notice to the other party hereto to the extent reasonably practicable) and (ii) to comply with Section 11.12. 

(SIGNATURES TO FOLLOW) 

  
 43 

 IN WITNESS WHEREOF, Borrower, Agent and Lender have duly executed and delivered this Loan
and Security Agreement as of the day and year first above written. 
  

			
	BORROWER:
	
	X4 PHARMACEUTICALS, INC.
		
	Signature:	 	/s/ Adam Mostafa
		
	Print Name:	 	Adam Mostafa
		
	Title:	 	Chief Financial Officer

 Accepted in Palo Alto, California: 

 

			
	AGENT:
	
	HERCULES CAPITAL, INC.
		
	Signature:	 	/s/ Jennifer Choe
		
	Print Name:	 	Jennifer Choe
		
	Title:	 	Associate General Counsel

  

			
	LENDER:
	
	HERCULES CAPITAL, INC.
		
	Signature:	 	/s/ Jennifer Choe
		
	Print Name:	 	Jennifer Choe
		
	Title:	 	Associate General Counsel

 Table of Exhibits and Schedules 

			
	
	Addendum 1 SBA Provisions
		
	Exhibit A:	  	Advance Request
	
	Attachment to Advance Request
		
	Exhibit B:	  	Term Note
		
	Exhibit C:	  	Name, Locations, and Other Information for Borrower
		
	Exhibit D:	  	Borrower’s Patents, Trademarks, Copyrights and Licenses
		
	Exhibit E:	  	Borrower’s Deposit Accounts and Investment Accounts
		
	Exhibit F:	  	Compliance Certificate
		
	Exhibit G:	  	Joinder Agreement
		
	Exhibit H:	  	ACH Debit Authorization Agreement
		
	Schedule 1	  	Subsidiaries
	Schedule 1.1	  	Commitments
	Schedule 1A	  	Existing Permitted Indebtedness
	Schedule 1B	  	Existing Permitted Investments
	Schedule 1C	  	Existing Permitted Liens
	Schedule 5.3	  	Consents, Etc.
	Schedule 5.5	  	Actions Before Governmental Authorities
	Schedule 5.8	  	Tax Matters
	Schedule 5.9	  	Intellectual Property Claims
	Schedule 5.10	  	Intellectual Property
	Schedule 5.11	  	Borrower Products
	Schedule 5.14	  	Capitalization

  
 2 

 ADDENDUM 1 to LOAN AND SECURITY AGREEMENT 

(a) Borrower’s Business. For purposes of this Addendum 1, Borrower shall be deemed to include its “affiliates” as
defined in Title 13 Code of Federal Regulations Section 121.103. Borrower represents and warrants to Agent and Lender as of the Closing Date and covenants to Agent and Lender for a period of one year after the Closing Date with respect to
subsections 2, 3, 4, 5, 6 and 7 below, as follows: 
  

	 	1.	 Size Status. Borrower’s primary NAICS code is 541714 and has fewer than 1,000 employees in the aggregate;

  

	 	2.	 No Relender. Borrower’s primary business activity does not involve, directly or indirectly, providing
funds to others, purchasing debt obligations, factoring, or long-term leasing of equipment with no provision for maintenance or repair; 

  

	 	3.	 No Passive Business. Borrower is engaged in a regular and continuous business operation (excluding the mere
receipt of payments such as dividends, rents, lease payments, or royalties). Borrower’s employees are carrying on the majority of day to day operations. Borrower will not pass through substantially all of the proceeds of the Loan to another
entity; 

  

	 	4.	 No Real Estate Business. Borrower is not classified under Major Group 65 (Real Estate) or Industry
No. 1531 (Operative Builders) of the SIC Manual. The proceeds of the Loan will not be used to acquire or refinance real property unless Borrower (x) is acquiring an existing property and will use at least 51 percent of the usable
square footage for its business purposes; (y) is building or renovating a building and will use at least 67 percent of the usable square footage for its business purposes; or (z) occupies the subject property and uses at least
67 percent of the usable square footage for its business purposes. 

  

	 	5.	 No Project Finance. Borrower’s assets are not intended to be reduced or consumed, generally without
replacement, as the life of its business progresses, and the nature of Borrower’s business does not require that a stream of cash payments be made to the business’s financing sources, on a basis associated with the continuing sale of
assets (e.g., real estate development projects and oil and gas wells). The primary purpose of the Loan is not to fund production of a single item or defined limited number of items, generally over a defined production period, where such production
will constitute the majority of the activities of Borrower (e.g., motion pictures and electric generating plants). 

  

	 	6.	 No Farm Land Purchases. Borrower will not use the proceeds of the Loan to acquire farm land which is or is
intended to be used for agricultural or forestry purposes, such as the production of food, fiber, or wood, or is so taxed or zoned. 

	 	7.	 No Foreign Investment. The proceeds of the Loan will not be used substantially for a foreign operation. At the
time of the Loan, Borrower will not have more than 49 percent of its employees or tangible assets located outside the United States of America. The representation in this subsection (7) is made only as of the date hereof and shall not
continue for one year as contemplated in the first sentence of this Section 1. 

 (b) Small Business
Administration Documentation. Agent and Lender acknowledge that Borrower completed, executed and delivered to Agent SBA Forms 480, 652 and 1031 (Parts A and B) together with a business plan showing Borrower’s financial projections
(including balance sheets and income and cash flows statements) for the period described therein and a written statement (whether included in the purchase agreement or pursuant to a separate statement) from Agent regarding its intended use of
proceeds from the sale of securities to Lender (the “Use of Proceeds Statement”). Borrower represents and warrants to Agent and Lender that the information regarding Borrower and its affiliates set forth in the SBA Form 480, Form 652 and
Form 1031 and the Use of Proceeds Statement delivered as of the Closing Date is accurate and complete. 
 (c) Inspection. The
following covenants contained in this Section (c) are intended to supplement and not to restrict the related provisions of the Loan Documents. Subject to the preceding sentence, Borrower will permit, for so long as Lender holds any debt or
equity securities of Borrower, Agent, Lender or their representative, at Agent’s or Lender’ expense, and examiners of the SBA to visit and inspect the properties and assets of Borrower, to examine its books of account and records, and to
discuss Borrower’s affairs, finances and accounts with Borrower’s officers, senior management and accountants, all at such reasonable times as may be requested by Agent or Lender or the SBA. 

(d) Annual Assessment. Promptly after the end of each calendar year (but in any event prior to February 28 of each year) and at
such other times as may be reasonably requested by Agent or Lender, Borrower will deliver to Agent a written assessment of the economic impact of Lender’s investment in Borrower, specifying the full-time equivalent jobs created or retained in
connection with the investment, the impact of the investment on the businesses of Borrower in terms of expanded revenue and taxes, other economic benefits resulting from the investment (such as technology development or commercialization, minority
business development, or expansion of exports) and such other information as may be required regarding Borrower in connection with the filing of Lender’s SBA Form 468. Lender will assist Borrower with preparing such assessment. In addition to
any other rights granted hereunder, Borrower will grant Agent and Lender and the SBA access to Borrower’s books and records for the purpose of verifying the use of such proceeds. Borrower also will furnish or cause to be furnished to Agent and
Lender such other information regarding the business, affairs and condition of Borrower as Agent or Lender may from time to time reasonably request. 

(e) Use of Proceeds. Borrower will use the proceeds from the Loan only for purposes set forth in Section 7.17. Borrower will
deliver to Agent from time to time promptly following Agent’s request, a written report, certified as correct by Borrower’s Chief Financial Officer, verifying the purposes and amounts for which proceeds from the Loan have been disbursed.
Borrower will supply to Agent such additional information and documents as Agent reasonably requests with respect to its use of proceeds and will permit Agent and Lender and the SBA to have access to any and all Borrower records and information and
personnel as Agent deems necessary to verify how such proceeds have been or are being used, and to assure that the proceeds have been used for the purposes specified in Section 7.17. 

  
 2 

 (f) Activities and Proceeds. Neither Borrower nor any of its affiliates (if any) will
engage in any activities or use directly or indirectly the proceeds from the Loan for any purpose for which a small business investment company is prohibited from providing funds by the SBIC Act, including 13 C.F.R. §107.720. Without obtaining
the prior written approval of Agent, Borrower will not change within 1 year of the date hereof, Borrower’s current business activity to a business activity which a licensee under the SBIC Act is prohibited from providing funds by the SBIC Act.

 (g) Redemption Provisions. Notwithstanding any provision to the contrary contained in the Certificate of Incorporation of
Borrower, as amended from time to time (the “Charter”), if, pursuant to the redemption provisions contained in the Charter, Lender is entitled to a redemption of its Warrant, such redemption (in the case of Lender) will be at a price equal
to the redemption price set forth in the Charter (the “Existing Redemption Price”). If, however, Lender delivers written notice to Borrower that the then current regulations promulgated under the SBIC Act prohibit payment of the Existing
Redemption Price in the case of an SBIC (or, if applied, the Existing Redemption Price would cause the Series B Preferred Stock, or next round, to the extent applicable, to lose its classification as an “equity security” and Lender has
determined that such classification is unadvisable), the amount Lender will be entitled to receive shall be the greater of (i) fair market value of the securities being redeemed taking into account the rights and preferences of such securities
plus any costs and expenses of the Lender incurred in making or maintaining the Warrant, and (ii) the Existing Redemption Price where the amount of accrued but unpaid dividends payable to the Lender is limited to Borrower’s earnings plus
any costs and expenses of the Lender incurred in making or maintaining the Warrant; provided, however, the amount calculated in subsections (i) or (ii) above shall not exceed the Existing Redemption Price. 

(h) Compliance and Resolution. Borrower agrees that a failure to comply with Borrower’s obligations under this Addendum, or any
other set of facts or circumstances where it has been asserted by any governmental regulatory agency (or Agent or Lender believes that there is a substantial risk of such assertion) that Agent, Lender and their affiliates are not entitled to hold,
or exercise any significant right with respect to, any securities issued to Lender by Borrower, will constitute a breach of the obligations of Borrower under the financing agreements among Borrower, Agent and Lender. In the event of (i) a
failure to comply with Borrower’s obligations under this Addendum; or (ii) an assertion by any governmental regulatory agency (or Agent or Lender believes that there is a substantial risk of such assertion) of a failure to comply with
Borrower’s obligations under this Addendum, then (i) Agent, Lender and Borrower will meet and resolve any such issue in good faith to the satisfaction of Borrower, Agent, Lender, and any governmental regulatory agency, and (ii) upon
request of Lender or Agent, Borrower will cooperate and assist with any assignment of the financing agreements among Hercules Technology III, L.P., Hercules Technology IV, L.P. and Hercules Capital, Inc. 

  
 3 

 EXHIBIT A 

ADVANCE REQUEST 
  

							
	To:	  	 Agent:
	  	Date:	  	_______________, 2018
		  	 Hercules Capital, Inc. (the “Agent”)
	  		  	
		  	 400 Hamilton Avenue, Suite 310
	  		  	
		  	 Palo Alto, CA 94301
	  		  	
		  	 email: legal@herculestech.com
	  		  	
		  	 Attn:
	  		  	

 X4 Pharmaceuticals, Inc. (“Borrower”) hereby requests from Hercules Capital, Inc. (“Lender”) an Advance in
the amount of _____________________ Dollars ($_____________) on _____________, _____ (the “Advance Date”) pursuant to the Loan and Security Agreement among Borrower, Agent and Lender (the “Agreement”). Capitalized
words and other terms used but not otherwise defined herein are used with the same meanings as defined in the Agreement. 
 Please: 

 

	 	(a)	 Issue a check payable to Borrower 

 

	 	or	 

  

	 	(b)	 Wire Funds to Borrower’s account 

 

			
	 Bank: 
	  	 
	 Address: 
	  	 
		  	 
	 ABA Number: 
	  	 
	 Account Number: 
	  	 
	 Account Name: 
	  	 
	 Contact Person: 
	  	 
	 Phone Number
	  	
	 To Verify Wire Info: 
	  	 
	 Email address: 
	  	 

 Borrower represents that the conditions precedent to the Advance set forth in the Agreement are satisfied and
shall be satisfied upon the making of such Advance, including but not limited to: (i) that no event that has had or could reasonably be expected to have a Material Adverse Effect has occurred and is continuing; (ii) that the
representations and warranties set forth in the Agreement and in the Warrant are and shall be true and correct in all material respects on and as of the Advance Date with the same effect as though made on and as of such date, except to the extent
such representations and warranties expressly relate to an earlier date; (iii) that Borrower is in compliance with all the terms and provisions set forth in each Loan Document on its part to be observed or performed; and (iv) that as of
the Advance Date, no fact or condition exists that could (or could, with the passage of time, the giving of notice, or both) constitute an Event of Default under the Loan Documents. Borrower understands and acknowledges that Agent has the right to
review the financial information supporting this representation and, based upon such review in its sole discretion, Lender may decline to fund the requested Advance. 

 Borrower hereby represents that Borrower’s corporate status and locations have not
changed since the date of the Agreement or, if the Attachment to this Advance Request is completed, are as set forth in the Attachment to this Advance Request. 

Borrower agrees to notify Agent promptly before the funding of the Loan if any of the matters which have been represented above shall not be
true and correct on the Borrowing Date and if Agent has received no such notice before the Advance Date then the statements set forth above shall be deemed to have been made and shall be deemed to be true and correct as of the Advance Date. 

Executed as of [            ], 20[    ]. 

 

			
	BORROWER: X4 PHARMACEUTICALS, INC.

 
			
		
	SIGNATURE:	 	 

 
			
	TITLE:	 	 

 
			
	PRINT NAME:	 	 

 ATTACHMENT TO ADVANCE REQUEST 

Dated: ________________________ 
 Borrower hereby
represents and warrants to Agent that Borrower’s current name and organizational status is as follows: 
  

			
	 Name:
	  	X4 Pharmaceuticals, Inc.
		
	 Type of organization:
	  	Corporation
		
	 State of organization:
	  	Delaware
		
	 Organization file number:
	  	5568691

 Borrower hereby represents and warrants to Agent that the street addresses, cities, states and postal codes of its current
locations are as follows: 

 EXHIBIT B 

SECURED TERM PROMISSORY NOTE 
  

			
	$[    ],000,000	  	Advance Date: ___ __, 20[    ]
		
		  	Maturity Date: _____ ___, 20[    ]

 FOR VALUE RECEIVED, X4 PHARMACEUTICALS, INC., a Delaware corporation, for itself and each of its Qualified
Subsidiaries (the “Borrower”) hereby promises to pay to the order of Hercules Capital, Inc., a Maryland corporation, or the holder of this Note (the “Lender”) at 400 Hamilton Avenue, Suite 310, Palo Alto, CA 94301 or such other
place of payment as the holder of this Secured Term Promissory Note (this “Promissory Note”) may specify from time to time in writing, in lawful money of the United States of America, the principal amount of [ ] Million Dollars ($[
],000,000) or such other principal amount as Lender has advanced to Borrower, together with interest at a rate as set forth in Section 2.2(c) of the Loan Agreement based upon a year consisting of 360 days, with interest computed daily based on
the actual number of days in each month. 
 This Promissory Note is the Note referred to in, and is executed and delivered in connection
with, that certain Loan and Security Agreement dated October 19, 2018, by and among Borrower, Hercules Capital, Inc., a Maryland corporation (the “Agent”) and the several banks and other financial institutions or entities from time to
time party thereto as lender (as the same may from time to time be amended, modified or supplemented in accordance with its terms, the “Loan Agreement”), and is entitled to the benefit and security of the Loan Agreement and the other Loan
Documents (as defined in the Loan Agreement), to which reference is made for a statement of all of the terms and conditions thereof. All payments shall be made in accordance with the Loan Agreement. All terms defined in the Loan Agreement shall have
the same definitions when used herein, unless otherwise defined herein. An Event of Default under the Loan Agreement shall constitute a default under this Promissory Note. 

Borrower waives presentment and demand for payment, notice of dishonor, protest and notice of protest under the UCC or any applicable law.
Borrower agrees to make all payments under this Promissory Note without setoff, recoupment or deduction and regardless of any counterclaim or defense. This Promissory Note has been negotiated and delivered to Lender and is payable in the State of
California. This Promissory Note shall be governed by and construed and enforced in accordance with, the laws of the State of California, excluding any conflicts of law rules or principles that would cause the application of the laws of any other
jurisdiction. 
  

							
	BORROWER FOR ITSELF AND	  		 		  	
	ON BEHALF OF ITS QUALIFIED SUBSIDIARIES:	  		 	 X4 PHARMACEUTICALS, INC.

							
				
		  		 	By: 	  	 
				
		  		 	Title: 	  	 

 EXHIBIT C 

NAME, LOCATIONS, AND OTHER INFORMATION FOR BORROWER 

1. Borrower represents and warrants to Agent that Borrower’s current name and organizational status as of the Closing Date is as follows:

  

			
	 Name:
	  	X4 Pharmaceuticals, Inc.
		
	 Type of organization:
	  	Corporation
		
	 State of organization:
	  	Delaware
		
	 Organization file number:
	  	5568691

 2. Borrower represents and warrants to Agent that for five (5) years prior to the Closing Date, Borrower
did not do business under any other name or organization or form except the following: 
 Name: 

Used during dates of: 
 Type of
Organization: 
 State of organization: 

Organization file Number: 

Borrower’s fiscal year ends on _____ 

Borrower’s federal employer tax identification number is: 

3. Borrower represents and warrants to Agent that its chief executive office is located at _________________. 

 EXHIBIT F 

COMPLIANCE CERTIFICATE 
 Hercules Capital,
Inc. (as “Agent”) 
 400 Hamilton Avenue, Suite 310 

Palo Alto, CA 94301 
 Reference is made to that
certain Loan and Security Agreement dated October 19, 2018 and the Loan Documents (as defined therein) entered into in connection with such Loan and Security Agreement all as may be amended from time to time (hereinafter referred to
collectively as the “Loan Agreement”) by and among Hercules Capital, Inc. (the “Agent”), the several banks and other financial institutions or entities from time to time party thereto (collectively, the “Lender”) and
Hercules Capital, Inc., as agent for the Lender (the “Agent”) and X4 Pharmaceuticals, Inc. (the “Company”) as Borrower. All capitalized terms not defined herein shall have the same meaning as defined in the Loan Agreement. 

The undersigned is an Officer of the Company, knowledgeable of all Company financial matters, and is authorized to provide certification of
information regarding the Company; hereby certifies, in such capacity, that in accordance with the terms and conditions of the Loan 

Agreement, the Company is in compliance for the period ending of all covenants, conditions and terms and hereby reaffirms that all
representations and warranties contained therein are true and correct on and as of the date of this Compliance Certificate with the same effect as though made on and as of such date, except to the extent such representations and warranties expressly
relate to an earlier date, after giving effect in all cases to any standard(s) of materiality contained in the Loan Agreement as to such representations and warranties. Attached are the required documents supporting the above certification. The
undersigned further certifies that these are prepared in accordance with GAAP (except for the absence of footnotes with respect to unaudited financial statement and subject to normal year end adjustments) and are consistent from one period to the
next except as explained below. 
  

					
	REPORTING
REQUIREMENT	  	REQUIRED	  	 CHECK IF

ATTACHED

			
	Interim Financial Statements	  	Monthly within 30 days	  	
			
	Interim Financial Statements	  	Quarterly within 45 Days	  	
			
	Audited Financial Statements	  	FYE within 180 days	  	
			
	Budget and forecast	  	At least annually within 60 days following FYE	  	

 7.22 MINIMUM CASH 
  

			
	(A) Are all Cash balances held by Borrower held in accounts subject to an Account Control Agreement? ____ Yes ____ No
		
	 (B)  If Yes,
	 	
		
	 (i) Balance of Cash Reserves
	 	$__________________________
		
	 (ii)  Aggregate Term Loan Advances outstanding
	 	$__________________________
		
	 (iii)  Cash balances held in accounts subject to an Account Control Agreement
	 	$__________________________
		
	Is item (iii) above equal to or greater than the lesser (i) and (ii)?	 	____ Yes ____ No
		
	Current statements showing balances held in all accounts subject to an Account Control Agreement are attached.	 	____ Yes ____ No

 The undersigned hereby also confirms the below disclosed accounts represent all depository accounts and securities accounts
presently open in the name of each Borrower or Borrower Subsidiary/Affiliate, as applicable. 
  

													
	 	  	 Depository
AC #
	  	 Financial
Institution
	  	 Account Type
(Depository /
Securities)
	  	 Last Month
Ending
Account
Balance
	  	 Purpose of
Account

	BORROWER Name/Address:	  	
							
		  	1	  		  		  		  		  	
							
		  	2	  		  		  		  		  	
							
		  	3	  		  		  		  		  	
							
		  	4	  		  		  		  		  	
							
		  	5	  		  		  		  		  	
							
		  	6	  		  		  		  		  	
							
		  	7	  		  		  		  		  	

													
						
	 	  	 	  	 	  	 	  	 	  	 
	BORROWER 
SUBSIDIARY / 
AFFILIATE 
COMPANY 
Name/Address	  	
							
		  	1	  		  		  		  		  	
							
		  	2	  		  		  		  		  	
							
		  	3	  		  		  		  		  	
							
		  	4	  		  		  		  		  	
							
		  	5	  		  		  		  		  	
							
		  	6	  		  		  		  		  	
							
		  	7	  		  		  		  		  	
	
	

  

			
	Very Truly Yours,
	
	X4 PHARMACEUTICALS, INC.

 
			
		
	By:         	 	 

 
			
		
	Name:   	 	 

 
			
		
	Its:         	 	 

 EXHIBIT G 

FORM OF JOINDER AGREEMENT 
 This Joinder
Agreement (the “Joinder Agreement”) is made and dated as of [        ], 20[    ], and is entered into by and between __________________., a __________ corporation
(“Subsidiary”), and HERCULES CAPITAL, INC., a Maryland corporation (as “Agent”). 
 RECITALS 

A. Subsidiary’s Affiliate, X4 Pharmaceuticals, Inc. (“Company”) has entered into that certain Loan and Security Agreement dated
October 19, 2018, with the several banks and other financial institutions or entities from time to time party thereto as lender (collectively, the “Lender”) and the Agent, as such agreement may be amended (the “Loan
Agreement”), together with the other agreements executed and delivered in connection therewith, including but not limited to the IP Security Agreement; 

B. Subsidiary acknowledges and agrees that it will benefit both directly and indirectly from Company’s execution of the Loan Agreement
and the other agreements executed and delivered in connection therewith; 
 AGREEMENT 

NOW THEREFORE, Subsidiary and Agent agree as follows: 
  

	1.	 The recitals set forth above are incorporated into and made part of this Joinder Agreement. Capitalized terms
not defined herein shall have the meaning provided in the Loan Agreement. 

  

	2.	 By signing this Joinder Agreement, Subsidiary shall be bound by the terms and conditions of the Loan Agreement
the same as if it were the Borrower (as defined in the Loan Agreement) under the Loan Agreement, mutatis mutandis, provided however, that (a) with respect to (i) Section 5.1 of the Loan Agreement, Subsidiary represents that it is an
entity duly organized, legally existing and in good standing under the laws of [        ], (b) neither Agent nor Lender shall have any duties, responsibilities or obligations to Subsidiary arising under or
related to the Loan Agreement or the other Loan Documents, (c) that if Subsidiary is covered by Company’s insurance, Subsidiary shall not be required to maintain separate insurance or comply with the provisions of Sections 6.1 and 6.2 of
the Loan Agreement, and (d) that as long as Company satisfies the requirements of Section 7.1 of the Loan Agreement, Subsidiary shall not have to provide Agent separate Financial Statements. To the extent that Agent or Lender has any
duties, responsibilities or obligations arising under or related to the Loan Agreement or the other Loan Documents, those duties, responsibilities or obligations shall flow only to Company and not to Subsidiary or any other Person or entity. By way
of example (and not an exclusive list): (i) Agent’s providing notice to Company in accordance with the Loan Agreement or as otherwise agreed among Company, Agent and Lender shall be deemed provided to Subsidiary; (ii) a Lender’s
providing an Advance to Company shall be deemed an Advance to Subsidiary; and (iii) Subsidiary shall have no right to request an Advance or make any other demand on Lender. 

	3.	 Subsidiary agrees not to certificate its equity securities without Agent’s prior written consent, which
consent may be conditioned on the delivery of such equity securities to Agent in order to perfect Agent’s security interest in such equity securities. 

  

	4.	 Subsidiary acknowledges that it benefits, both directly and indirectly, from the Loan Agreement, and hereby
waives, for itself and on behalf on any and all successors in interest (including without limitation any assignee for the benefit of creditors, receiver, bankruptcy trustee or itself as
debtor-in-possession under any bankruptcy proceeding) to the fullest extent provided by law, any and all claims, rights or defenses to the enforcement of this Joinder
Agreement on the basis that (a) it failed to receive adequate consideration for the execution and delivery of this Joinder Agreement or (b) its obligations under this Joinder Agreement are avoidable as a fraudulent conveyance.

  

	5.	 As security for the prompt, complete payment when due (whether on the payment dates or otherwise) of all the
Secured Obligations, Subsidiary grants to Agent a security interest in all of Subsidiary’s right, title, and interest in and to the Collateral. 

[REMAINDER OF PAGE INTENTIONALLY LEFT BLANK] 

 [SIGNATURE PAGE TO JOINDER AGREEMENT] 

SUBSIDIARY: 
  

			
	
———————————————————

		
	
                   
 
	 	By:
		 	Name:
		 	Title:
		
		 	Address:
		
		 	Telephone: _____________________
		 	email: ______________________
	
	 AGENT:

	
	 HERCULES CAPITAL, INC.

		
		 	By:       ————————————————
		 	Name:  ————————————————
		 	Title:    ———————————————––
		
		 	 Address:
 400 Hamilton Ave., Suite 310

Palo Alto, CA 94301
 email: legal@herculestech.com

Telephone: 650-289-3060

 EXHIBIT H 

ACH DEBIT AUTHORIZATION AGREEMENT 

Hercules Capital, Inc. 
 400 Hamilton Avenue, Suite 310 

Palo Alto, CA 94301 
  

	 	Re:	 Loan and Security Agreement dated October 19, 2018 (the “Agreement”) by and among X4
Pharmaceuticals, Inc. (“Borrower”) and Hercules Capital, Inc., as agent (“Company”) and the lenders party thereto (collectively, the “Lender”) 

In connection with the above referenced Agreement, the Borrower hereby authorizes the Company to initiate debit entries for (i) the periodic payments due
under the Agreement and (ii) out-of-pocket legal fees and costs incurred by Agent or Lender pursuant to Section 11.11 of the Agreement to the Borrower’s
account indicated below. The Borrower authorizes the depository institution named below to debit to such account. 
  

			
	DEPOSITORY NAME	  	BRANCH
		
	CITY	  	STATE AND ZIP CODE
		
	TRANSIT/ABA NUMBER	  	ACCOUNT NUMBER

 This authority will remain in full force and effect so long as any amounts are due under the Agreement. 

 

			
	X4 PHARMACEUTICALS, INC.

			
		
	By: 	 	 

			
		
	Date:

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