EX-10.3





 Exhibit 10.3 

TSCAN THERAPEUTICS, INC. 

2021 EQUITY INCENTIVE PLAN 

(As Adopted on April 22, 2021) 












 TSCAN THERAPEUTICS, INC. 

2021 EQUITY INCENTIVE PLAN 

ARTICLE 1.    INTRODUCTION. 

The Board adopted the Plan to become effective immediately, although no Awards may be granted prior to the IPO Date. The purpose of the Plan is
to promote the long-term success of the Company and the creation of stockholder value by (a) encouraging Service Providers to focus on critical long-range corporate objectives, (b) encouraging the attraction and retention of Service
Providers with exceptional qualifications and (c) linking Service Providers directly to stockholder interests through increased stock ownership. The Plan seeks to achieve this purpose by providing for Awards in the form of Options (which may be
ISOs or NSOs), SARs, Restricted Shares and Restricted Stock Units. Capitalized terms used in this Plan are defined in Article 14. 
 ARTICLE
2.    ADMINISTRATION. 
 2.1    General. The Plan may be administered by the
Board or one or more Committees to which the Board (or an authorized Board committee) has delegated authority. If administration is delegated to a Committee, the Committee shall have the powers theretofore possessed by the Board, including, to the
extent permitted by applicable law, the power to delegate to a subcommittee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to either the Board or the Administrator shall hereafter also encompass
the Committee or subcommittee, as applicable). The Board may abolish the Committee’s delegation at any time and the Board shall at all times also retain the authority it has delegated to the Committee. The Administrator shall comply with rules
and regulations applicable to it, including under the rules of any exchange on which the Common Shares are traded, and shall have the authority and be responsible for such functions as have been assigned to it. 

2.2    Section 16. To the extent desirable to qualify transactions hereunder as exempt under Exchange Act
Rule 16b-3, the transactions contemplated hereunder will be approved by the entire Board or a Committee of two or more “non-employee directors” within the
meaning of Exchange Act Rule 16b-3. 
 2.3    Powers of
Administrator. Subject to the terms of the Plan, and in the case of a Committee, subject to the specific duties delegated to the Committee, the Administrator shall have the authority to (a) select the Service Providers who are to receive
Awards under the Plan, (b) determine the type, number, vesting requirements and other features and conditions of such Awards, (c) interpret the Plan and Awards granted under the Plan, (d) determine whether, when and to what extent an
Award has become vested and/or exercisable and whether any performance-based vesting conditions have been satisfied, (e) make, amend and rescind rules relating to the Plan and Awards granted under the Plan, including rules relating to sub-plans established for the purposes of satisfying applicable foreign laws or for qualifying for favorable tax treatment under applicable foreign laws, (f) impose such restrictions, conditions or limitations
as it determines appropriate as to the timing and manner of any resales by a Participant of any Common Shares issued pursuant to an Award, including restrictions under an insider trading policy and restrictions as to the use of a specified brokerage
firm for such resales, 












 
and (g) make all other decisions relating to the operation of the Plan and Awards granted under the Plan. In addition, with regard to the terms and conditions of Awards granted to Service
Providers outside of the United States, the Administrator may vary from the provisions of the Plan (other than any requiring stockholder approval pursuant to Section 13.3) to the extent it determines it necessary and appropriate to do so. 

2.4    Effect of Administrator’s Decisions. The Administrator’s decisions, determinations and
interpretations shall be final and binding on all interested parties. 
 2.5    Governing Law. The Plan
shall be governed by, and construed in accordance with, the laws of the State of Delaware (except its choice-of-law provisions). 

ARTICLE 3.    SHARES AVAILABLE FOR GRANTS. 

3.1    Basic Limitation. Common Shares issued pursuant to the Plan may be authorized but unissued shares or
treasury shares. The aggregate number of Common Shares issued under the Plan shall not exceed the sum of (a) 26,880,000 Common Shares, (b) any Common Shares subject to awards granted under the Predecessor Plan that are outstanding on the
IPO Date that subsequently are forfeited, expire or lapse unexercised or unsettled and Common Shares issued pursuant to awards granted under the Predecessor Plan that are outstanding on the IPO Date and that are subsequently forfeited to or
reacquired by the Company, (c) the number of Common Shares reserved under the Predecessor Plan that are not issued or subject to outstanding awards under the Predecessor Plan on the IPO Date and (d) the additional Common Shares described
in Articles 3.2 and 3.3. The Company shall reserve and keep available such number of Common Shares as will be sufficient to satisfy the requirements of the Plan. The numerical limitations in this Article 3.1 shall be subject to
adjustment pursuant to Article 9. 
 3.2    Annual Increase in Shares. On the first day of each fiscal year of the Company during the term of the Plan, commencing in 2022 and ending in (and including) 2031, the aggregate number of Common Shares that may be issued under the Plan shall
automatically increase by a number equal to the lesser of (a) 5% of the total number of Common Shares actually issued and outstanding on the last day of the preceding fiscal year or (b) a number of Common Shares determined by the Board.

 3.3    Shares Returned to Reserve. To the extent that Options, SARs, Restricted Stock Units or other
Awards are forfeited, cancelled or expire for any reason before being exercised or settled in full, the Common Shares subject to such Awards shall again become available for issuance under the Plan. If SARs are exercised or Restricted Stock Units
are settled, then only the number of Common Shares (if any) actually issued to the Participant upon exercise of such SARs or settlement of such Restricted Stock Units, as applicable, shall reduce the number of Common Shares available under
Article 3.1 and the balance shall again become available for issuance under the Plan. If Restricted Shares or Common Shares issued upon the exercise of Options are reacquired by the Company pursuant to a forfeiture provision, repurchase right
or for any other reason, then such Common Shares shall again become available for issuance under the Plan. Common Shares applied to pay the Exercise Price of Options or to satisfy tax withholding obligations related to any Award shall again become
available for issuance under the Plan. To the extent that an Award is settled in cash rather than Common Shares, the cash settlement shall not reduce the number of Shares available for issuance under the Plan. 












 3.4    Awards Not Reducing Share Reserve. To the extent
permitted under applicable exchange listing standards, any dividend equivalents paid or credited under the Plan with respect to Restricted Stock Units shall not be applied against the number of Common Shares that may be issued under the Plan,
whether or not such dividend equivalents are converted into Restricted Stock Units. In addition, Common Shares subject to Substitute Awards granted by the Company shall not reduce the number of Common Shares that may be issued under Article 3.1, nor
shall shares subject to Substitute Awards again be available for Awards under the Plan in the event of any forfeiture, expiration or cash settlement of such Substitute Awards. 

3.5    Code Section 422 and Other Limits. Subject to adjustment in accordance with
Article 9: 
 (a)    No more than 26,880,000 Common Shares may be issued under the Plan upon the exercise of ISOs. 

(b)    The aggregate grant date fair value of Awards granted to an Outside Director during any one fiscal year of the
Company, together with the value of any cash compensation paid to the Outside Director during such fiscal year, may not exceed $750,000 (on a per-Director basis); provided however that the limitation that will
apply in the fiscal year in which the Outside Director is initially appointed or elected to the Board shall instead be $1,500,000. For purposes of this limitation, the grant date fair value of an Award shall be determined in accordance with the
assumptions that the Company uses to estimate the value of share-based payments for financial reporting purposes. For the sake of clarity, neither Awards granted, nor compensation paid, to an individual for his or her service as an Employee or
Consultant, but not as an Outside Director, shall count towards this limitation. 
 ARTICLE 4.    ELIGIBILITY. 

4.1    Incentive Stock Options. Only Employees who are common-law
employees of the Company, a Parent or a Subsidiary shall be eligible for the grant of ISOs. In addition, an Employee who owns more than 10% of the total combined voting power of all classes of outstanding stock of the Company or any of its Parents
or Subsidiaries shall not be eligible for the grant of an ISO unless the additional requirements set forth in Code Section 422(c)(5) are satisfied. 

4.2    Other Awards. Awards other than ISOs may be granted to both Employees and other Service
Providers. 
 ARTICLE 5.    OPTIONS. 

5.1    Stock Option Agreement. Each grant of an Option under the Plan shall be evidenced by a Stock Option
Agreement between the Optionee and the Company. Such Option shall be subject to all applicable terms of the Plan and may be subject to any other terms that are not inconsistent with the Plan. The Stock Option Agreement shall specify whether the
Option is intended to be an ISO or an NSO. The provisions of the various Stock Option Agreements entered into under the Plan need not be identical. 

5.2    Number of Shares. Each Stock Option Agreement shall specify the number of Common Shares subject to
the Option, which number shall adjust in accordance with Article 9. 












 5.3    Exercise Price. Each Stock Option Agreement shall
specify the Exercise Price, which shall not be less than 100% of the Fair Market Value of a Common Share on the date of grant. The preceding sentence shall not apply to an Option that is a Substitute Award granted in a manner that would satisfy the
requirements of Code Section 409A and, if applicable, Code Section 424(a). 
 5.4    Exercisability
and Term. Each Stock Option Agreement shall specify the date or event when all or any installment of the Option is to become vested and/or exercisable. The vesting and exercisability conditions applicable to the Option may include service-based
conditions, performance-based conditions, such other conditions as the Administrator may determine, or any combination of such conditions. The Stock Option Agreement shall also specify the term of the Option; provided that, except to the extent
necessary to comply with applicable foreign law, the term of an Option shall in no event exceed 10 years from the date of grant. A Stock Option Agreement may provide for accelerated vesting and/or exercisability upon certain specified events
and may provide for expiration prior to the end of its term in the event of the termination of the Optionee’s service. 

5.5    Death of Optionee. After an Optionee’s death, any vested and exercisable Options held by
such Optionee may be exercised by his or her beneficiary or beneficiaries. Each Optionee may designate one or more beneficiaries for this purpose by filing the prescribed form with the Company. A beneficiary designation may be changed by filing the
prescribed form with the Company at any time before the Optionee’s death. If no beneficiary was designated or if no designated beneficiary survives the Optionee, then any vested and exercisable Options held by the Optionee may be exercised by
his or her estate. 
 5.6    Modification or Assumption of Options. Within the limitations of the Plan,
the Administrator may modify, extend or assume outstanding options. The foregoing notwithstanding, no modification of an Option shall, without the consent of the Optionee, materially impair his or her rights or obligations under such Option.
Notwithstanding anything in this Plan to the contrary, and except for the adjustments provided in Article 9, neither the Administrator nor any other person may (a) decrease the exercise price for any outstanding Option after the date of grant,
(b) cancel or allow an Optionee to surrender an outstanding Option to the Company in exchange for cash or as consideration for the grant of a new Option with a lower exercise price or the grant of another type of Award the effect of which is to
reduce the exercise price of any outstanding Option, or (c) take any other action with respect to an Option that would be treated as a repricing under the rules and regulations of the Nasdaq Stock Market (or such other principal U.S. national
securities exchange on which the Common Shares are traded). 
 5.7    Buyout Provisions. Except to the
extent prohibited by Article 5.6, the Administrator may at any time (a) offer to buy out for a payment in cash or cash equivalents an Option previously granted or (b) authorize an Optionee to elect to cash out an Option previously granted,
in either case at such time and based upon such terms and conditions as the Administrator shall establish. 

5.8    Payment for Option Shares. The entire Exercise Price of Common Shares issued upon exercise of Options
shall be payable in cash or cash equivalents at the time when such Common Shares are purchased. In addition, the Administrator may, in its sole discretion 












 
and to the extent permitted by applicable law, accept payment of all or a portion of the Exercise Price through any one or a combination of the following forms or methods: 

(a)    Subject to any conditions or limitations established by the Administrator, by surrendering, or attesting to the
ownership of, Common Shares that are already owned by the Optionee with a value on the date of surrender equal to the aggregate exercise price of the Common Shares as to which such Option will be exercised; 

(b)    By delivering (on a form prescribed by the Company) an irrevocable direction to a securities broker approved by the
Company to sell all or part of the Common Shares being purchased under the Plan and to deliver all or part of the sales proceeds to the Company; 

(c)    Subject to such conditions and requirements as the Administrator may impose from time to time, through a net
exercise procedure; or 
 (d)    Through any other form or method consistent with applicable laws, regulations and
rules. 
 ARTICLE 6.    STOCK APPRECIATION RIGHTS. 

6.1    SAR Agreement. Each grant of a SAR under the Plan shall be evidenced by a SAR Agreement between the
Optionee and the Company. Such SAR shall be subject to all applicable terms of the Plan and may be subject to any other terms that are not inconsistent with the Plan. The provisions of the various SAR Agreements entered into under the Plan need not
be identical. 
 6.2    Number of Shares. Each SAR Agreement shall specify the number of Common Shares to
which the SAR pertains, which number shall adjust in accordance with Article 9. 
 6.3    Exercise
Price. Each SAR Agreement shall specify the Exercise Price, which shall in no event be less than 100% of the Fair Market Value of a Common Share on the date of grant. The preceding sentence shall not apply to a SAR that is a Substitute Award
granted in a manner that would satisfy the requirements of Code Section 409A. 
 6.4    Exercisability
and Term. Each SAR Agreement shall specify the date when all or any installment of the SAR is to become vested and exercisable. The vesting and exercisability conditions applicable to the SAR may include service-based conditions,
performance-based conditions, such other conditions as the Administrator may determine, or any combination thereof. The SAR Agreement shall also specify the term of the SAR; provided that except to the extent necessary to comply with applicable
foreign law, the term of a SAR shall not exceed 10 years from the date of grant. A SAR Agreement may provide for accelerated vesting and exercisability upon certain specified events and may provide for expiration prior to the end of its term in the
event of the termination of the Optionee’s service. 
 6.5    Exercise of SARs. Upon exercise of a
SAR, the Optionee (or any person having the right to exercise the SAR after his or her death) shall receive from the Company (a) Common Shares, (b) cash or (c) a combination of Common Shares and cash, as the Administrator shall
determine. The amount of cash and/or the Fair Market Value of Common Shares received upon exercise of SARs shall, in the aggregate, not exceed the amount by which the Fair Market Value 












 
(on the date of surrender) of the Common Shares subject to the SARs exceeds the Exercise Price. If, on the date when a SAR expires, the Exercise Price is less than the Fair Market Value on such
date but any portion of such SAR has not been exercised or surrendered, then such SAR shall automatically be deemed to be exercised as of such date with respect to such portion. A SAR Agreement may also provide for an automatic exercise of the SAR
on an earlier date. 
 6.6    Death of Optionee. After an Optionee’s death, any vested and
exercisable SARs held by such Optionee may be exercised by his or her beneficiary or beneficiaries. Each Optionee may designate one or more beneficiaries for this purpose by filing the prescribed form with the Company. A beneficiary designation may
be changed by filing the prescribed form with the Company at any time before the Optionee’s death. If no beneficiary was designated or if no designated beneficiary survives the Optionee, then any vested and exercisable SARs held by the Optionee
at the time of his or her death may be exercised by his or her estate. 
 6.7    Modification or Assumption of
SARs. Within the limitations of the Plan, the Administrator may modify, extend or assume outstanding SARs. The foregoing notwithstanding, no modification of a SAR shall, without the consent of the Optionee, materially impair his or her rights or
obligations under such SAR. Notwithstanding anything in this Plan to the contrary, and except for the adjustments provided in Article 9, neither the Administrator nor any other person may (a) decrease the exercise price for any outstanding SAR
after the date of grant, (b) cancel or allow an Optionee to surrender an outstanding SAR to the Company in exchange for cash or as consideration for the grant of a new SAR with a lower exercise price or the grant of another type of Award the
effect of which is to reduce the exercise price of any outstanding SAR, or (c) take any other action with respect to a SAR that would be treated as a repricing under the rules and regulations of the Nasdaq Stock Market (or such other principal
U.S. national securities exchange on which the Common Shares are traded). 
 ARTICLE 7.    RESTRICTED SHARES. 

7.1    Restricted Stock Agreement. Each grant of Restricted Shares under the Plan shall be evidenced by a
Restricted Stock Agreement between the recipient and the Company. Such Restricted Shares shall be subject to all applicable terms of the Plan and may be subject to any other terms that are not inconsistent with the Plan. The provisions of the
various Restricted Stock Agreements entered into under the Plan need not be identical. 
 7.2    Payment for
Awards. Restricted Shares may be sold or awarded under the Plan for such consideration as the Administrator may determine, including (without limitation) cash, cash equivalents, property, cancellation of other equity awards, promissory notes,
past services and future services, and such other methods of payment as are permitted by applicable law. 

7.3    Vesting Conditions. Each Award of Restricted Shares may or may not be subject to vesting and/or other
conditions as the Administrator may determine. Vesting shall occur, in full or in installments, upon satisfaction of the conditions specified in the Restricted Stock Agreement. A Restricted Stock Agreement may provide for accelerated vesting upon
certain specified events. 
 7.4    Voting and Dividend Rights. The holders of Restricted Shares awarded
under the Plan shall have the same voting, dividend and other rights as the Company’s other stockholders, unless the Administrator otherwise provides. A Restricted Stock Agreement, 












 
however, may require that any cash dividends paid on Restricted Shares (a) be accumulated and paid when such Restricted Shares vest, or (b) be invested in additional Restricted Shares.
Such additional Restricted Shares shall be subject to the same conditions and restrictions as the shares subject to the Award with respect to which the dividends were paid. In addition, if any dividends or other distributions are paid in Common
Shares, such Common Shares shall be subject to the same restrictions on transferability and forfeitability as the Restricted Shares with respect to which they were paid. 

7.5    Modification or Assumption of Restricted Shares. Within the limitations of the Plan, the
Administrator may modify or assume outstanding Restricted Shares or may accept the cancellation of outstanding restricted shares (whether granted by the Company or by another issuer) in return for the grant of new Restricted Shares for the same or a
different number of shares or in return for the grant of a different type of Award. The foregoing notwithstanding, no modification of Restricted Shares shall, without the consent of the Participant, materially impair his or her rights or obligations
under such Restricted Shares. 
 ARTICLE 8.    RESTRICTED STOCK UNITS. 

8.1    Restricted Stock Unit Agreement. Each grant of Restricted Stock Units under the Plan shall be
evidenced by a Restricted Stock Unit Agreement between the recipient and the Company. Such Restricted Stock Units shall be subject to all applicable terms of the Plan and may be subject to any other terms that are not inconsistent with the Plan. The
provisions of the various Restricted Stock Unit Agreements entered into under the Plan need not be identical. 

8.2    Payment for Awards. To the extent that an Award is granted in the form of Restricted Stock Units, no
cash consideration shall be required of the Award recipients. 
 8.3    Vesting Conditions. Each Award of
Restricted Stock Units may or may not be subject to vesting, as determined by the Administrator. Vesting shall occur, in full or in installments, upon satisfaction of the conditions specified in the Restricted Stock Unit Agreement. Vesting
conditions may include service-based conditions, performance-based conditions, such other conditions as the Administrator may determine, or any combination thereof. A Restricted Stock Unit Agreement may provide for accelerated vesting upon certain
specified events. 
 8.4    Voting and Dividend Rights. The holders of Restricted Stock Units shall have
no voting rights. Prior to settlement or forfeiture, Restricted Stock Units awarded under the Plan may, at the Administrator’s discretion, provide for a right to dividend equivalents. Such right entitles the holder to be credited with an amount
equal to all cash dividends paid on one Common Share while the Restricted Stock Unit is outstanding. Dividend equivalents may be converted into additional Restricted Stock Units. Settlement of dividend equivalents may be made in the form of cash, in
the form of Common Shares, or in a combination of both. Prior to distribution, any dividend equivalents shall be subject to the same conditions and restrictions as the Restricted Stock Units to which they attach. 

8.5    Form and Time of Settlement of Restricted Stock Units. Settlement of vested Restricted
Stock Units may be made in the form of (a) cash, (b) Common Shares or (c) any combination of both, as determined by the Administrator. The actual number of Restricted Stock Units eligible for settlement may be larger or smaller than
the number included in the original 












 
Award, based on predetermined performance factors. Methods of converting Restricted Stock Units into cash may include (without limitation) a method based on the average value of Common Shares
over a series of trading days. Vested Restricted Stock Units shall be settled in such manner and at such time(s) as specified in the Restricted Stock Unit Agreement. Until an Award of Restricted Stock Units is settled, the number of such Restricted
Stock Units shall be subject to adjustment pursuant to Article 9. 
 8.6    Death of Recipient. Any
Restricted Stock Units that become payable after the recipient’s death shall be distributed to the recipient’s beneficiary or beneficiaries. Each recipient of Restricted Stock Units under the Plan may designate one or more beneficiaries
for this purpose by filing the prescribed form with the Company. A beneficiary designation may be changed by filing the prescribed form with the Company at any time before the Award recipient’s death. If no beneficiary was designated or if no
designated beneficiary survives the Award recipient, then any Restricted Stock Units that become payable after the recipient’s death shall be distributed to the recipient’s estate. 

8.7    Modification or Assumption of Restricted Stock Units. Within the limitations of the
Plan, the Administrator may modify or assume outstanding restricted stock units or may accept the cancellation of outstanding restricted stock units (whether granted by the Company or by another issuer) in return for the grant of new Restricted
Stock Units for the same or a different number of shares or in return for the grant of a different type of Award. The foregoing notwithstanding, no modification of a Restricted Stock Unit shall, without the consent of the Participant, materially
impair his or her rights or obligations under such Restricted Stock Unit. 

8.8    Creditors’ Rights. A holder of Restricted Stock Units shall have no rights other
than those of a general creditor of the Company. Restricted Stock Units represent an unfunded and unsecured obligation of the Company, subject to the terms and conditions of the applicable Restricted Stock Unit Agreement. 

ARTICLE 9.    ADJUSTMENTS; DISSOLUTIONS AND LIQUIDATIONS; CORPORATE TRANSACTIONS. 

9.1    Adjustments. In the event of a subdivision of the outstanding Common Shares, a declaration of a
dividend payable in Common Shares, a combination or consolidation of the outstanding Common Shares (by reclassification or otherwise) into a lesser number of Common Shares or any other increase or decrease in the number of issued Common Shares
effected without receipt of consideration by the Company, proportionate adjustments shall be made to the following: 

(a)    The number and kind of shares available for issuance under Article 3, including the numerical share limits in
Articles 3.1 and 3.5; 
 (b)    The number and kind of shares covered by each outstanding Option, SAR, and Restricted
Stock Unit; and/or 
 (c)    The Exercise Price applicable to each outstanding Option and SAR, and the repurchase price,
if any, applicable to Restricted Shares. 
 In the event of a declaration of an extraordinary dividend payable in a form other than Common Shares in an
amount that has a material effect on the price of Common Shares, a recapitalization, 












 
a spin-off or a similar occurrence, the Administrator shall make such adjustments as it, in its sole discretion, deems appropriate to the foregoing. Any
adjustment in the number of shares subject to an Award under this Article 9.1 shall be rounded down to the nearest whole share, although the Administrator in its sole discretion may make a cash payment in lieu of a fractional share. Except as
provided in this Article 9, a Participant shall have no rights by reason of any issuance by the Company of stock of any class or securities convertible into stock of any class, any subdivision or consolidation of shares of stock of any class,
the payment of any stock dividend or any other increase or decrease in the number of shares of stock of any class. 

9.2    Dissolution or Liquidation. To the extent not previously exercised or settled, Options, SARs and
Restricted Stock Units shall terminate immediately prior to the dissolution or liquidation of the Company. 

9.3    Corporate Transactions. In the event that the Company is a party to a merger, consolidation, or a
Change in Control (other than one described in Article 14.6(d)), all Common Shares acquired under the Plan and all Awards outstanding on the effective date of the transaction shall be treated in the manner described in the definitive transaction
agreement (or, in the event the transaction does not entail a definitive agreement to which the Company is party, in the manner determined by the Administrator, with such determination having final and binding effect on all parties), which agreement
or determination need not treat all Awards (or portions thereof) in an identical manner. Unless an Award Agreement provides otherwise, the treatment specified in the transaction agreement or by the Administrator may include (without limitation) one
or more of the following with respect to each outstanding Award: 
 (a)    The continuation of such
outstanding Award by the Company (if the Company is the surviving entity); 
 (b)    The assumption of
such outstanding Award by the surviving entity or its parent, provided that the assumption of an Option or a SAR shall comply with applicable tax requirements; 

(c)    The substitution by the surviving entity or its parent of an equivalent award for such outstanding
Award (including, but not limited to, an award to acquire the same consideration paid to the holders of Common Shares in the transaction), provided that the substitution of an Option or a SAR shall comply with applicable tax requirements; 

(d)    In the case of an Option or SAR, the cancellation of such Award without payment of any
consideration. An Optionee shall be able to exercise his or her outstanding Option or SAR, to the extent such Option or SAR is then vested or become vested as of the effective time of the transaction, during a period of not less than five full
business days preceding the closing date of the transaction, unless (i) a shorter period is required to permit a timely closing of the transaction and (ii) such shorter period still offers the Optionees a reasonable opportunity to exercise
such Option or SAR. Any exercise of such Option or SAR during such period may be contingent on the closing of the transaction; 

(e)    The cancellation of such Award and a payment to the Participant with respect to each share subject
to the portion of the Award that is vested or 












 
becomes vested as of the effective time of the transaction equal to the excess of (A) the value, as determined by the Administrator in its absolute discretion, of the property
(including cash) received by the holder of a Common Share as a result of the transaction, over (if applicable) (B) the per-share Exercise Price of such Award (such excess, if any, the “Spread”). Such payment shall be made
in the form of cash, cash equivalents, or securities of the surviving entity or its parent having a value equal to the Spread. In addition, any escrow, holdback, earn-out or similar provisions in the
transaction agreement may apply to such payment to the same extent and in the same manner as such provisions apply to the holders of Common Shares. If the Spread applicable to an Award (whether or not vested) is zero or a negative number,
then the Award may be cancelled without making a payment to the Participant. In the event that an Award is subject to Code Section 409A, the payment described in this clause (e) shall be made on the settlement date specified in the
applicable Award Agreement, provided that settlement may be accelerated in accordance with Treasury Regulation Section 1.409A-3(j)(4); or 

(f)    The assignment of any reacquisition or repurchase rights held by the Company in respect of an Award
of Restricted Shares to the surviving entity or its parent, with corresponding proportionate adjustments made to the price per share to be paid upon exercise of any such reacquisition or repurchase rights. 

Unless an Award Agreement provides otherwise, each outstanding Award held by a Participant who remains a Service Provider as of the effective time of a
merger, consolidation or Change in Control (other than one described in Article 14.6(d)) (a “Current Participant”) shall become fully vested and, if applicable, exercisable immediately prior to the effective time of the transaction
and, in the case of an Award subject to performance-based vesting conditions, such performance-based vesting conditions shall be deemed achieved at 100% of target levels. However, the prior sentence shall not apply, and an outstanding Award
shall not become vested and, if applicable, exercisable, if and to the extent the Award is continued, assumed or substituted as provided for in clauses (a), (b) or (c) above. In addition, the prior two sentences shall not apply to an
Award held by a Participant who is not a Current Participant unless an Award Agreement provides otherwise or unless the Company and the acquirer agree otherwise. 

For avoidance of doubt, the Administrator shall have the discretion, exercisable either at the time an Award is granted or at any time while the Award remains
outstanding, to provide for the acceleration of vesting upon the occurrence of a Change in Control, whether or not the Award is to be assumed or replaced in the transaction, or in connection with a termination of the Participant’s service
following a transaction. 
 Any action taken under this Article 9.3 shall either preserve an Award’s status as exempt from Code Section 409A or
comply with Code Section 409A. 
 ARTICLE 10.    OTHER AWARDS. 

Subject in all events to the limitations under Article 3 above as to the number of Common Shares available for issuance under this Plan, the
Company may grant other forms of Awards not specifically described herein and may grant awards under other plans or programs, where such awards are settled in the form of Common Shares issued under this Plan. Such Common Shares shall be treated for
all purposes under the Plan like Common Shares issued in settlement of Restricted Stock Units and shall, when issued, reduce the number of Common Shares available under Article 3. 












 ARTICLE 11.    LIMITATION ON RIGHTS. 

11.1    Retention Rights. Neither the Plan nor any Award granted under the Plan shall be deemed to give any
individual a right to remain a Service Provider. The Company and its Parents, Subsidiaries and Affiliates reserve the right to terminate the Service of any Service Provider at any time, with or without cause, subject to applicable laws, the
Company’s certificate of incorporation and by-laws and a written employment agreement (if any). 

11.2    Stockholders’ Rights. Except as set forth in Article 7.4 or 8.4 above, a
Participant shall have no dividend rights, voting rights or other rights as a stockholder with respect to any Common Shares covered by his or her Award prior to the time when a stock certificate for such Common Shares is issued or, if applicable,
the time when he or she becomes entitled to receive such Common Shares by filing any required notice of exercise and paying any required Exercise Price. No adjustment shall be made for cash dividends or other rights for which the record date is
prior to such time, except as expressly provided in the Plan. 
 11.3    Regulatory Requirements. Any
other provision of the Plan notwithstanding, the obligation of the Company to issue Common Shares under the Plan shall be subject to all applicable laws, rules and regulations and such approval by any regulatory body as may be required. The Company
reserves the right to restrict, in whole or in part, the delivery of Common Shares pursuant to any Award prior to the satisfaction of all legal requirements relating to the issuance of such Common Shares, to their registration, qualification or
listing or to an exemption from registration, qualification or listing. The inability of the Company to obtain authority from any regulatory body having jurisdiction, which authority is deemed necessary by the Company’s counsel to be necessary
to the lawful issuance and sale of any Common Shares hereunder, will relieve the Company of any liability in respect of the failure to issue or sell such Common Shares as to which such requisite authority will not have been obtained. 

11.4    Transferability of Awards. The Administrator may, in its sole discretion, permit
transfer of an Award in a manner consistent with applicable law. Unless otherwise determined by the Administrator, Awards shall be transferable by a Participant only by (a) beneficiary designation, (b) a will or (c) the laws of
descent and distribution; provided that, in any event, an ISO may only be transferred by will or by the laws of descent and distribution and may be exercised during the lifetime of the Optionee only by the Optionee or by the Optionee’s guardian
or legal representative. 
 11.5    Recoupment Policy. All Awards granted under the Plan, all
amounts paid under the Plan and all Common Shares issued under the Plan shall be subject to recoupment, clawback or recovery by the Company in accordance with applicable law and with Company policy (whenever adopted) regarding same, whether or not
such policy is intended to satisfy the requirements of the Dodd-Frank Wall Street Reform and Consumer Protection Act, the Sarbanes-Oxley Act, or other applicable law, as well as any implementing regulations and/or listing standards thereunder. 

11.6    Other Conditions and Restrictions on Common Shares. Any Common Shares issued under the Plan shall be
subject to such forfeiture conditions, rights of repurchase, rights of 












 
first refusal, other transfer restrictions and such other terms and conditions as the Administrator may determine. Such conditions and restrictions shall be set forth in the applicable Award
Agreement and shall apply in addition to any restrictions that may apply to holders of Common Shares generally. In addition, Common Shares issued under the Plan shall be subject to such conditions and restrictions imposed either by applicable law or
by Company policy, as adopted from time to time, designed to ensure compliance with applicable law or laws with which the Company determines in its sole discretion to comply including in order to maintain any statutory, regulatory or tax advantage.

 ARTICLE 12.    TAXES. 

12.1    General. It is a condition to each Award under the Plan that a Participant or his or her successor
shall make arrangements satisfactory to the Company for the satisfaction of any federal, state, local or foreign withholding tax obligations that arise in connection with any Award granted under the Plan. The Company shall not be required to issue
any Common Shares or make any cash payment under the Plan unless such obligations are satisfied. 

12.2    Share Withholding. To the extent that applicable law subjects a Participant to tax withholding
obligations, the Administrator may permit such Participant to satisfy all or part of such obligations by having the Company withhold all or a portion of any Common Shares that otherwise would be issued to him or her or by surrendering all or a
portion of any Common Shares that he or she previously acquired. Such Common Shares shall be valued on the date when they are withheld or surrendered. Any payment of taxes by assigning Common Shares to the Company may be subject to restrictions
including any restrictions required by SEC, accounting or other rules. 
 12.3    Section 409A Matters.
Except as otherwise expressly set forth in an Award Agreement, it is intended that Awards granted under the Plan either be exempt from, or comply with, the requirements of Code Section 409A. To the extent an Award is subject to Code
Section 409A (a “409A Award”), the terms of the Plan, the Award and any written agreement governing the Award shall be interpreted to comply with the requirements of Code Section 409A so that the Award is not subject to
additional tax or interest under Code Section 409A, unless the Administrator expressly provides otherwise. A 409A Award shall be subject to such additional rules and requirements as specified by the Administrator from time to time in order for
it to comply with the requirements of Code Section 409A. In this regard, if any amount under a 409A Award is payable upon a “separation from service” to an individual who is considered a “specified employee” (as each term is
defined under Code Section 409A), then no such payment shall be made prior to the date that is the earlier of (i) six months and one day after the Participant’s separation from service or (ii) the Participant’s death, but
only to the extent such delay is necessary to prevent such payment from being subject to Code Section 409A(a)(1). 

12.4    Limitation on Liability. Neither the Company nor any person serving as Administrator shall have any
liability to a Participant in the event an Award held by the Participant fails to achieve its intended characterization under applicable tax law. 

ARTICLE 13.    FUTURE OF THE PLAN. 

13.1    Term of the Plan. The Plan, as set forth herein, shall become effective on the date of its adoption
by the Board, subject to approval of the Company’s stockholders under Article 13.3 below. The Plan shall terminate automatically 10 years after the date when the Board adopted the Plan. 












 13.2    Amendment or Termination. The Board may, at any
time and for any reason, amend or terminate the Plan. No Awards shall be granted under the Plan after the termination thereof. The termination of the Plan, or any amendment thereof, shall not affect any Award previously granted under the Plan. 

13.3    Stockholder Approval. To the extent required by applicable law, the Plan will be subject to the
approval of the Company’s stockholders within 12 months of its adoption date. An amendment of the Plan shall be subject to the approval of the Company’s stockholders only to the extent required by applicable laws, regulations or rules.

 ARTICLE 14.    DEFINITIONS. 

14.1    “Administrator” means the Board or any Committee administering the Plan in accordance with Article
2. 
 14.2    “Affiliate” means any entity other than a Subsidiary, if the Company and/or one or more
Subsidiaries own not less than 50% of such entity. 
 14.3    “Award” means any award granted under the
Plan, including as an Option, a SAR, a Restricted Share award, a Restricted Stock Unit award or another form of equity-based compensation award. 

14.4    “Award Agreement” means a Stock Option Agreement, a SAR Agreement, a Restricted Stock Agreement,
a Restricted Stock Unit Agreement or such other agreement evidencing an Award granted under the Plan. 

14.5    “Board” means the Company’s Board of Directors, as constituted from time to time and, where
the context so requires, reference to the “Board” may refer to a Committee to whom the Board has delegated authority to administer any aspect of this Plan. 

14.6    “Change in Control” means: 

(a)    Any “person” (as such term is used in Sections 13(d) and 14(d) of the Exchange Act) becomes the
“beneficial owner” (as defined in Rule 13d-3 of the Exchange Act), directly or indirectly, of securities of the Company representing more than fifty percent (50%) of the total voting power
represented by the Company’s then-outstanding voting securities; 
 (b)    The consummation of the sale or
disposition by the Company of all or substantially all of the Company’s assets; 
 (c)    The consummation of a
merger or consolidation of the Company with or into any other entity, other than a merger or consolidation which would result in the voting securities of the Company outstanding immediately prior thereto continuing to represent (either by remaining
outstanding or by being converted into voting securities of the surviving entity or its parent) more than fifty percent (50%) of the total voting power represented by the voting securities of the Company or such surviving entity or its parent
outstanding immediately after such merger or consolidation; or 












 (d)    Individuals who are members of the Board (the “Incumbent
Board”) cease for any reason to constitute at least a majority of the members of the Board over a period of 12 months; provided, however, that if the appointment or election (or nomination for election) of any new Board member was approved
or recommended by a majority vote of the members of the Incumbent Board then still in office, such new member shall, for purposes of this Plan, be considered as a member of the Incumbent Board. 

A transaction shall not constitute a Change in Control if its sole purpose is to change the state of the Company’s incorporation or to create a holding
company that will be owned in substantially the same proportions by the persons who held the Company’s securities immediately before such transaction. In addition, if a Change in Control constitutes a payment event with respect to any
Award which provides for a deferral of compensation and is subject to Code Section 409A, then notwithstanding anything to the contrary in the Plan or applicable Award Agreement the transaction with respect to such Award must also constitute a
“change in control event” as defined in Treasury Regulation Section 1.409A-3(i)(5) to the extent required by Code Section 409A. 

14.7    “Code” means the Internal Revenue Code of 1986, as amended. 

14.8    “Committee” means a committee of one or more members of the Board, or of other individuals
satisfying applicable laws, appointed by the Board to administer the Plan. 
 14.9    “Common Share”
means one share of the Company’s common stock. 
 14.10    “Company” means TScan Therapeutics,
Inc., a Delaware corporation. 
 14.11    “Consultant” means a consultant or adviser who provides
bona fide services to the Company, a Parent, a Subsidiary or an Affiliate as an independent contractor and who qualifies as a consultant or advisor under Instruction A.1.(a)(1) of Form S-8 under the
Securities Act. 
 14.12    “Employee” means a common-law
employee of the Company, a Parent, a Subsidiary or an Affiliate. 
 14.13    “Exchange Act” means the
Securities Exchange Act of 1934, as amended. 
 14.14    “Exercise Price,” in the case of an Option,
means the amount for which one Common Share may be purchased upon exercise of such Option, as specified in the applicable Stock Option Agreement. “Exercise Price,” in the case of a SAR, means an amount, as specified in the applicable SAR
Agreement, which is subtracted from the Fair Market Value of one Common Share in determining the amount payable upon exercise of such SAR. 

14.15    “Fair Market Value” means the closing price of a Common Share on any established stock exchange
or a national market system on the applicable date or, if the applicable date is not a trading day, on the last trading day prior to the applicable date, as reported in a source that the Administrator deems reliable. If Common Shares are not traded
on an established stock exchange or a national market system, the Fair Market Value shall be determined by the Administrator in good faith on such basis as it deems appropriate. The Administrator’s determination shall be conclusive and binding
on all persons. Notwithstanding the foregoing, the determination of the Fair Market Value in all cases shall be in accordance with the requirements set forth under Section 409A of the Code to the extent necessary for an Award to comply with, or
be exempt from, Section 409A of the Code. 












 14.16    “IPO Date” means the effective date of the
registration statement filed by the Company with the Securities and Exchange Commission for its initial offering of the Common Shares to the public. 

14.17    “ISO” means an incentive stock option described in Code Section 422(b). 

14.18    “NSO” means a stock option not described in Code Sections 422 or 423. 

14.19    “Option” means an ISO or NSO granted under the Plan and entitling the holder to purchase Common
Shares. 
 14.20    “Optionee” means an individual or estate holding an Option or SAR. 

14.21    “Outside Director” means a member of the Board who is not an Employee. 

14.22    “Parent” means any corporation (other than the Company) in an unbroken chain of corporations
ending with the Company, if each of the corporations other than the Company owns stock possessing 50% or more of the total combined voting power of all classes of stock in one of the other corporations in such chain. A corporation that attains the
status of a Parent on a date after the adoption of the Plan shall be considered a Parent commencing as of such date. 

14.23    “Participant” means an individual or estate holding an Award. 

14.24    “Plan” means this TScan Therapeutics, Inc. 2021 Equity Incentive Plan, as amended from time to
time. 
 14.25    “Predecessor Plan” means the Company’s 2018 Stock Plan, as amended. 

14.26    “Restricted Share” means a Common Share awarded under the Plan. 

14.27    “Restricted Stock Agreement” means the agreement consistent with the terms of the Plan between
the Company and the recipient of a Restricted Share that contains the terms, conditions and restrictions pertaining to such Restricted Share. 

14.28    “Restricted Stock Unit” means a bookkeeping entry representing the equivalent of one Common
Share, as awarded under the Plan. 
 14.29    “Restricted Stock Unit Agreement” means the agreement
consistent with the terms of the Plan between the Company and the recipient of a Restricted Stock Unit that contains the terms, conditions and restrictions pertaining to such Restricted Stock Unit. 

14.30    “SAR” means a stock appreciation right granted under the Plan. 

14.31    “SAR Agreement” means the agreement consistent with the terms of the Plan between the Company
and an Optionee that contains the terms, conditions and restrictions pertaining to his or her SAR. 












 14.32    “Securities Act” means the Securities Act of
1933, as amended. 
 14.33    “Service Provider” means any individual who is an Employee, Outside
Director or Consultant, including any prospective Employee, Outside Director or Consultant who has accepted an offer of employment or service and will be an Employee, Outside Director or Consultant after the commencement of their service. 

14.34    “Stock Option Agreement” means the agreement consistent with the terms of the Plan between the
Company and an Optionee that contains the terms, conditions and restrictions pertaining to his or her Option. 

14.35    “Subsidiary” means any corporation (other than the Company) in an unbroken chain of corporations
beginning with the Company, if each of the corporations other than the last corporation in the unbroken chain owns stock possessing 50% or more of the total combined voting power of all classes of stock in one of the other corporations in such
chain. A corporation that attains the status of a Subsidiary on a date after the adoption of the Plan shall be considered a Subsidiary commencing as of such date 

14.36    “Substitute Awards” means Awards or Common Shares issued by the Company in assumption of, or
substitution or exchange for, awards previously granted, or the right or obligation to make future awards, in each case by a corporation acquired by the Company or any Affiliate or with which the Company or any Affiliate combines to the extent
permitted by the applicable exchange listing standards.