# EDGAR Filing Document

**Accession Number:** 0001687968
**File Stem:** 0000950170-25-108341
**Filing Date:** 2025-8
**Character Count:** 25056
**Document Hash:** 972cd9c0e1c620120284885a4b1b96b5
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000950170-25-108341.hdr.sgml**: 20250813

**ACCESSION NUMBER**: 0000950170-25-108341

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20250813

**DATE AS OF CHANGE**: 20250813

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** X4 Pharmaceuticals, Inc
- **CENTRAL INDEX KEY:** 0001501697
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 273181608
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-90199
- **FILM NUMBER:** 251213873

**BUSINESS ADDRESS:**
- **STREET 1:** 61 NORTH BEACON STREET
- **STREET 2:** 4TH FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02134
- **BUSINESS PHONE:** 857-529-8300

**MAIL ADDRESS:**
- **STREET 1:** 61 NORTH BEACON STREET
- **STREET 2:** 4TH FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02134

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Arsanis, Inc.
- **DATE OF NAME CHANGE:** 20100920
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Bain Capital Life Sciences Fund, L.P.
- **CENTRAL INDEX KEY:** 0001687968

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** E9
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D

**BUSINESS ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 617-516-2000

**MAIL ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116

### Attached PDF Documents

**Attachment 1:** `ck0000000000-ex99_a.pdf`

_No text found in this document._

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**X4 PHARMACEUTICALS, INC.**

*(Name of Issuer)*

**Common Stock, par value $0.001 per share**

*(Title of Class of Securities)*

**98420X202**

*(CUSIP Number)*

**Bain Capital Life Sciences Inv**<br>200 Clarendon Street<br>Boston MA 02116<br>617-516-2000

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**08/11/2025**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **98420X202** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Bain Capital Life Sciences Fund, L.P.** | Name of reporting person<br>**Bain Capital Life Sciences Fund, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**2436526.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**2436526.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.99%** | Percent of class represented by amount in Row (11)<br>**9.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **98420X202** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Bain Capital Life Sciences Fund II, L.P.** | Name of reporting person<br>**Bain Capital Life Sciences Fund II, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**2436526.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**2436526.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.99%** | Percent of class represented by amount in Row (11)<br>**9.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **98420X202** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**BCIP Life Sciences Associates, LP** | Name of reporting person<br>**BCIP Life Sciences Associates, LP** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**2436526.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**2436526.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.99%** | Percent of class represented by amount in Row (11)<br>**9.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **98420X202** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**BCLS II Investco, LP** | Name of reporting person<br>**BCLS II Investco, LP** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**2436526.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**2436526.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.99%** | Percent of class represented by amount in Row (11)<br>**9.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **98420X202** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**BCLS I Investco, LP** | Name of reporting person<br>**BCLS I Investco, LP** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**2436526.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**2436526.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | Aggregate amount beneficially owned by each reporting person<br>**2436526.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**9.99%** | Percent of class represented by amount in Row (11)<br>**9.99%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, par value $0.001 per share

**(b) Name of Issuer:**
X4 PHARMACEUTICALS, INC.

**(c) Address of Issuer's Principal Executive Offices:**
61 North Beacon Street, 4th Floor, Boston, MA, 02134

**Item 4. Purpose of Transaction**

Concurrent with the August 2025 Financing, the Issuer's board of directors (the "Board") approved (i) the termination of each of the Chief Executive Officer and Chief Financial Officer of the Company and (ii) the appointment of an Executive Chairman, a new Chief Financial Officer and a new President of the Company.

**Item 5. Interest in Securities of the Issuer**

**(a)**
The information set forth in Items 2, 3 and 6 and on the cover pages of this Schedule 13D is incorporated by reference in its entirety into this Item 5.

As of the date hereof, (i) BCLS Fund I directly holds 18,898 shares of Common Stock and a pre-funded warrant exercisable for up to 18,898 shares of Common Stock; (ii) BCLS Fund II directly holds 44,409 shares of Common Stock and pre-funded warrants exercisable for up to 20,056 shares of Common Stock; (iii) BCIPLS directly holds 7,343 shares of Common Stock and pre-funded warrants exercisable for up to 4,376 shares of Common Stock; (iv) BCLS II Investco directly holds 309,002 shares of Common Stock, pre-funded warrants to purchase up to 7,290,677 shares of Common Stock, a Warrant (as defined below) exercisable for up to 214,956 shares of Common Stock and a Classs C Warrant (as defined below) exercisable for up to 68,818 shares of Common Stock; and (v) BCLS I Investco directly holds 116,339 shares of Common Stock, pre-funded warrants exercisable for up to 62,952 shares of Common Stock, a Warrant exercisable for up to 89,633 shares of Common Stock and a Class C Warrant exercisable for up to 28,696 shares of Common Stock.

As a result of the Beneficial Ownership Blockers (as defined below), the Reporting Persons are precluded from (i) exercising the Warrants or pre-funded warrants into shares of Common Stock to the extent that the Reporting Persons would, after such exercise, collectively beneficially own in excess of 9.99% of the outstanding Common Stock of the Issuer and (ii) exercising the Class C Warrants into shares of Common Stock to the extent that the Reporting Persons would, after such exercise, collectively beneficially own in excess of 4.99% of the outstanding Common Stock of the Issuer. Accordingly, pursuant to Rule 13d-3 of the Act and the relationships described in Item 2 of this Schedule 13D, the Reporting Persons may be deemed to collectively beneficially own 9.99% of the outstanding Common Stock of the Issuer, representing 2,436,526 shares of Common Stock as of the date hereof.

The calculation of the beneficial ownership of the Reporting Persons is based on (i) 11,408,357 shares of Common Stock issued and outstanding as of August 4, 2025, as reported by the Issuer in its Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025, filed with the Securities and Exchange Commission on August 8, 2025; (ii) 11,040,776 shares of Common Stock issued by the Issuer in the August 2025 Financing; and (iii) 1,940,535 shares of Common Stock issuable upon the exercise of Warrants, Class C Warrants and pre-funded warrants held by the Reporting Persons, which reflects the Beneficial Ownership Blockers.

**(b)**
See Item 5(a) hereof.

**(c)**
See Item 3 of this Schedule 13D.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

Pre-Funded Warrants

References to and the description of the pre-funded warrants set forth in this Item 6 do not purport to be complete and are qualified in their entirety by reference to the form of pre-funded warrant, which is attached hereto as Exhibit C and incorporated by reference herein.

Exercisability. Each pre-funded warrant held by the Reporting Persons is exercisable at any time after its original issuance.

Exercise Blocker. Exercise of each pre-funded warrant is prohibited if, as a result of such exercise, the holder, together with its affiliates and other persons whose beneficial ownership would be aggregated with the holder's for purposes of Section 13(d) of the Act, would beneficially own more than 9.99% of the total number of shares of Common Stock then issued and outstanding immediately after giving effect to the exercise (the "Pre-Funded Warrant Exercise Blocker").

Exercise Price. The Reporting Persons hold pre-funded warrants exercisable for up to (i) 7,047,216 shares of Common Stock with an exercise price of $0.001 per share; (ii) 255,589 shares of Common Stock with an exercise price of $0.03 per share; and (iii) 94,154 shares of Common Stock with an exercise price of $0.30 per share. The exercise price is subject to appropriate adjustment in the event of certain stock dividends and distributions, stock splits, stock combinations or reclassifications affecting the Common Stock.

Fundamental Transaction. If a Fundamental Transaction (as defined in the pre-funded warrant) occurs while a pre-funded warrant is outstanding, then upon any subsequent exercise of the pre-funded warrant, the holder thereof has the right to receive the same amount and kind of securities, cash or property as such holder would have been entitled to receive upon the occurrence of such Fundamental Transaction if it had been, immediately prior to such Fundamental Transaction, the holder of the number of shares of Common Stock then issuable upon exercise in full of the pre-funded warrant (without regard to any limitations on exercise).

Rights as a Stockholder. Except as otherwise provided in the pre-funded warrant or by virtue of the holder's ownership of Common Stock, the holder of a pre-funded warrant does not have the rights or privileges of a holder of Common Stock, including any voting rights, until the holder exercises the pre-funded warrant.

Warrant

References to and the description of the Warrant (the "Warrant") set forth in this Item 6 do not purport to be complete and are qualified in their entirety by reference to the form of Warrant, which is attached hereto as Exhibit D and incorporated by reference herein.

Exercisability. The Warrant is exercisable at any time after its original issuance and will expire on July 6, 2027.

Exercise Blocker. Exercise of the Warrant is prohibited if, as a result of such exercise, the holder, together with its affiliates and other persons whose beneficial ownership would be aggregated with the holder's for purposes of Section 13(d) of the Act, would beneficially own more than 9.99% of the total number of shares of Common Stock then issued and outstanding immediately after giving effect to the exercise (the "Warrant Exercise Blocker").

Exercise Price. The Warrant has an exercise price equal to $32.85 per share. The exercise price is subject to appropriate adjustment in the event of certain stock dividends and distributions, stock splits, stock combinations or reclassifications affecting the Common Stock.

Fundamental Transaction. If a Fundamental Transaction (as defined in the Warrant) occurs while a Warrant is outstanding, then upon any subsequent exercise of the Warrant, the holder thereof has the right to receive the same amount and kind of securities, cash or property as such holder would have been entitled to receive upon the occurrence of such Fundamental Transaction if it had been, immediately prior to such Fundamental Transaction, the holder of the number of shares of Common Stock then issuable upon exercise in full of the Warrant (without regard to any limitations on exercise).

Rights as a Stockholder. Except as otherwise provided in the Warrant or by virture of the holder's ownership of Common Stock, the holder of a Warrant does not have the rights or privileges of a holder of Common Stock, including any voting rights, until the holder exercises the Warrant.

Class C Warrant

References to and descriptions of the Class C Warrant (the "Class C Warrant") set forth in this Item 6 do not purport to be complete and are qualified in their entirety by reference to the form of Class C Warrant, which is attached hereto as Exhibit E and incorporated by reference herein.

Exercisability. The Class C Warrant is exercisable at any time after its original issuance and will expire on December 9, 2027.

Exercise Blocker. Exercise of the Class C Warrant is prohibited if, as a result of such exercise, the holder, together with its affiliates and other persons whose beneficial ownership would be aggregated with the holder's for purposes of Section 13(d) of the Act, would beneficially own more than 4.99% of the total number of shares of Common Stock then issued and outstanding immediately after giving effect to the exercise (together with the Pre-Funded Warrant Exercise Blocker and the Warrant Exercise Blocker, the "Beneficial Ownership Blockers").

Exercise Price. The Class C Warrant has an exercise price equal to $45.00 per share. The exercise price is subject to appropriate adjustment in the event of certain stock dividends and distributions, stock splits, stock combinations or reclassifications affecting the Common Stock.

Fundamental Transaction. If a Fundamental Transaction (as defined in the Class C Warrant) occurs while a Class C Warrant is outstanding, then upon any subsequent exercise of the Class C Warrant, the holder thereof has the right to receive the same amount and kind of securities, cash or property as such holder would have been entitled to receive upon the occurrence of such Fundamental Transaction if it had been, immediately prior to such Fundamental Transaction, the holder of the number of shares of Common Stock then issuable upon exercise in full of the Class C Warrant (without regard to any limitations on exercise).

Rights as a Stockholder. Except as otherwise provided in the Class C Warrant or by viture of the holder's ownership of Common Stock, the holder of a Class C Warrant does not have the rights or privileges of a holder of Common Stock, including any voting rights, until the holder exercises the Class C Warrant.

Registration Rights Agreements

References to and descriptions of the registration rights agreements set forth in this Item 6 do not purport to be complete and are qualified in their entirety by reference to the registration rights agreements that are attached hereto as Exhibits F through K and incorporated by reference herein.

The Reporting Persons have entered into resale registration rights agreements with the Issuer pursuant to which the Issuer agreed to file registration statements covering the resale, by the Reporting Persons, of certain shares of Common Stock held by the Reporting Persons and to use commercially reasonable efforts to cause such registration statements to remain effective until such time as all such shares of Common Stock have been sold or no longer qualify as registrable securities.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Bain Capital Life Sciences Fund, L.P.

**Signature:** /s/ Andrew Hack

**Name/Title:** Andrew Hack, Partner of Bain Capital Life Sciences Investors, LLC

**Date:** 08/13/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Bain Capital Life Sciences Fund II, L.P.

**Signature:** /s/ Andrew Hack

**Name/Title:** Andrew Hack, Partner of Bain Capital Life Sciences Investors, LLC

**Date:** 08/13/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** BCIP Life Sciences Associates, LP

**Signature:** /s/ Andrew Hack

**Name/Title:** Andrew Hack, Authorized Signatory of Boylston Coinvestors, LLC

**Date:** 08/13/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** BCLS II Investco, LP

**Signature:** /s/ Andrew Hack

**Name/Title:** Andrew Hack, Partner of Bain Capital Life Sciences Investors, LLC

**Date:** 08/13/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** BCLS I Investco, LP

**Signature:** /s/ Andrew Hack

**Name/Title:** Andrew Hack, Partner of Bain Capital Life Sciences Investors, LLC

**Date:** 08/13/2025