Document:

EX-4.1

 Exhibit 4.1 

SYNDAX PHARMACEUTICALS, INC. 

WARRANT TO PURCHASE COMMON STOCK 
  

			
		  	 Number of Shares: [            ]

(subject to adjustment)

	 Warrant No.
	  	Original Issue Date: [            ]

 Syndax Pharmaceuticals, Inc., a Delaware corporation (the “Company”), hereby certifies that,
for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, [            ] or its permitted registered assigns (the “Holder”), is
entitled, subject to the terms set forth below, to purchase from the Company up to a total of [            ] shares of common stock, $0.0001 par value per share (the “Common
Stock”), of the Company (each such share, a “Warrant Share” and all such shares, the “Warrant Shares”) at an exercise price per share equal to $0.0001 per share (as adjusted from time to time as provided in
Section 9 herein, the “Exercise Price”), upon surrender of this Warrant to Purchase Common Stock (including any Warrants to Purchase Common Stock issued in exchange, transfer or replacement hereof, the
“Warrant”) at any time and from time to time on or after the date hereof (the “Original Issue Date”) and through and including 5:30 P.M., New York City time, on the date that is 20 years following the Original Issue
Date (the “Expiration Date”), and subject to the following terms and conditions: 
 1. Definitions. For purposes of this Warrant,
the following terms shall have the following meanings: 
 (a) “Affiliate” means any Person directly or indirectly
controlled by, controlling or under common control with, a Holder, but only for so long as such control shall continue. For purposes of this definition, “control” (including, with correlative meanings, “controlled by,”
“controlling” and “under common control with”) means, with respect to a Person, possession, direct or indirect, of (a) the power to direct or cause direction of the management and policies of such Person (whether through
ownership of securities or partnership or other ownership interests, by contract or otherwise), or (b) at least 50% of the voting securities (whether directly or pursuant to any option, warrant or other similar arrangement) or other comparable
equity interests. 
 (b) “Commission” means the United States Securities and Exchange Commission. 

(c) “Closing Sale Price” means, for any security as of any date, the last trade price for such security on the Principal
Trading Market for such security, as reported by Bloomberg Financial Markets, or, if such Principal Trading Market begins to operate on an extended hours basis and does not designate the last trade price, then the last trade price of such security
prior to 4:00 P.M., New York City time, as reported by Bloomberg Financial Markets, or if the foregoing do not apply, the last trade price of such security in the
over-the-counter market on the electronic bulletin board for such security as reported by Bloomberg Financial Markets, or, if no last trade price is reported for such
security by Bloomberg Financial Markets, the average of the bid and ask prices, of any market makers for such security as reported in the “pink sheets” by Pink Sheets LLC. If the Closing Sale Price cannot be calculated for a security on a
particular date on any of the foregoing bases, the Closing Sale Price of such security on such date shall be the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair
market value of such security, then the Board of Directors of the Company shall use its good faith judgment to determine the fair market value. The Board of Directors’ determination shall be binding upon all parties absent demonstrable error.
All such determinations shall be appropriately adjusted for any stock dividend, stock split, stock combination or other similar transaction during the applicable calculation period. 

(d) “Principal Trading Market” means the national securities exchange or other trading market on which the Common Stock is
primarily listed on and quoted for trading, which, as of the Original Issue Date, shall be The Nasdaq Global Select Market. 
 (e)
“Securities Act” means the Securities Act of 1933, as amended. 
 (f) “Trading Day” means any weekday on
which the Principal Trading Market is open for trading. 
 (g) “Transfer Agent” means Computershare Trust Company, N.A.,
the Company’s transfer agent and registrar for the Common Stock, and any successor appointed in such capacity. 
 2. Registration of Warrants.
The Company shall register this Warrant, upon records to be maintained by the Company for that 

  
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purpose (the “Warrant Register”), in the name of the record Holder (which shall include the initial Holder or, as the case may be, any registered assignee to which this Warrant
is permissibly assigned hereunder) from time to time. The Company may deem and treat the registered Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or any distribution to the Holder, and for all other
purposes, absent actual notice to the contrary. 
 3. Registration of Transfers. Subject to compliance with all applicable securities laws, the
Company shall, or will cause its Transfer Agent to, register the transfer of all or any portion of this Warrant in the Warrant Register, upon surrender of this Warrant, and payment for all applicable transfer taxes (if any). Upon any such
registration or transfer, a new warrant to purchase Common Stock in substantially the form of this Warrant (any such new warrant, a “New Warrant”) evidencing the portion of this Warrant so transferred shall be issued to the
transferee, and a New Warrant evidencing the remaining portion of this Warrant not so transferred, if any, shall be issued to the transferring Holder. The acceptance of the New Warrant by the transferee thereof shall be deemed the acceptance by such
transferee of all of the rights and obligations in respect of the New Warrant that the Holder has in respect of this Warrant. The Company shall, or will cause its Transfer Agent to, prepare, issue and deliver at the Company’s own expense any
New Warrant under this Section 3. Until due presentment for registration of transfer, the Company may treat the registered Holder hereof as the owner and holder for all purposes, and the Company shall not be affected by any
notice to the contrary. 
 4. Exercise and Duration of Warrants. 

(a) All or any part of this Warrant shall be exercisable by the registered Holder in any manner permitted by
Section 10 of this Warrant at any time and from time to time on or after the Original Issue Date and through and including 5:30 P.M. New York City time, on the Expiration Date. At 5:30 P.M., New York City time, on the
Expiration Date, the portion of this Warrant not exercised prior thereto shall be and become void and of no value and this Warrant shall be terminated and no longer outstanding. 

(b) The Holder may exercise this Warrant by delivering to the Company (i) an exercise notice, in the form attached as Schedule 1
hereto (the “Exercise Notice”), completed and duly signed, and (ii) payment of the Exercise Price for the number of Warrant Shares as to which this Warrant is being exercised (which may take the form of a “cashless
exercise” if so indicated in the Exercise Notice pursuant to Section 10 below), and the date on which the last of such items is delivered to the Company (as determined in accordance with the notice provisions hereof)
is an “Exercise Date.” The Holder shall not be required to deliver the original Warrant in order to effect an exercise hereunder. Execution and delivery of the Exercise Notice shall have the same effect as cancellation of the
original Warrant and issuance of a New Warrant evidencing the right to purchase the remaining number of Warrant Shares. 
 5. Delivery of Warrant
Shares. 
 (a) Upon exercise of this Warrant, the Company shall promptly (but in no event later than two Trading Days after the Exercise
Date), upon the request of the Holder, credit such aggregate number of shares of Common Stock to which the Holder is entitled pursuant to such exercise to the Holder’s or its designee’s balance account with The Depository Trust Company
(“DTC”) through its Deposit Withdrawal Agent Commission system, or if the Transfer Agent is not participating in the Fast Automated Securities Transfer Program (the “FAST Program”) or if the certificates are
required to bear a legend regarding restriction on transferability, issue and dispatch by overnight courier to the address as specified in the Exercise Notice, a certificate, registered in the Company’s share register in the name of the Holder
or its designee, for the number of shares of Common Stock to which the Holder is entitled pursuant to such exercise. The Holder, or any natural person or legal entity (each, a “Person”) permissibly so designated by the Holder to
receive Warrant Shares, shall be deemed to have become the holder of record of such Warrant Shares as of the Exercise Date, irrespective of the date such Warrant Shares are credited to the Holder’s DTC account or the date of delivery of the
certificates evidencing such Warrant Shares, as the case may be. 
 (b) If by the close of the second Trading Day after the Exercise Date,
the Company fails to deliver to the Holder a certificate representing the required number of Warrant Shares in the manner required pursuant to Section 5(a) or fails to credit the Holder’s balance account with DTC for
such number of Warrant Shares to which the Holder is entitled, and if after such second Trading Day and prior to the receipt of such Warrant Shares, the Holder purchases (in an open market transaction or otherwise) shares of Common Stock to deliver
in satisfaction of a sale by the Holder of the Warrant Shares which the Holder anticipated receiving upon such exercise (a “Buy-In”), then the Company shall, within two Trading Days after the
Holder’s request and in the Holder’s sole discretion, either (1) pay in cash to the Holder an amount equal to the Holder’s total purchase price (including brokerage commissions, if any) for the shares of Common Stock so purchased
(the “Buy-In Price”), at which point the Company’s obligation to deliver such certificate (and to issue such Warrant Shares) shall terminate or (2) promptly honor its obligation to
deliver to the Holder a certificate or certificates representing such Warrant Shares and pay cash to the Holder in an amount equal to the excess (if any) of Holder’s total purchase price (including brokerage commissions, if any) for the shares
of Common Stock so purchased in the Buy-In over the product of (A) the number of shares of Common Stock purchased in the Buy-In, times (B) the Closing Sale
Price of a share of Common Stock on the Exercise Date. 

  
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 (c) To the extent permitted by law and subject to 5(b), the Company’s obligations to issue
and deliver Warrant Shares in accordance with and subject to the terms hereof (including the limitations set forth in Section 11 below) are absolute and unconditional, irrespective of any action or inaction by the Holder to
enforce the same, any waiver or consent with respect to any provision hereof, the recovery of any judgment against any Person or any action to enforce the same, or any setoff, counterclaim, recoupment, limitation or termination, or any breach or
alleged breach by the Holder or any other Person of any obligation to the Company or any violation or alleged violation of law by the Holder or any other Person, and irrespective of any other circumstance that might otherwise limit such obligation
of the Company to the Holder in connection with the issuance of Warrant Shares. Subject to Section 5(b), nothing herein shall limit the Holder’s right to pursue any other remedies available to it hereunder, at law or in equity including,
without limitation, a decree of specific performance and/or injunctive relief with respect to the Company’s failure to timely deliver certificates representing shares of Common Stock upon exercise of the Warrant as required pursuant to the
terms hereof. 
 6. Charges, Taxes and Expenses. Issuance and delivery of certificates for shares of Common Stock upon exercise of this Warrant shall
be made without charge to the Holder for any issue or transfer tax, transfer agent fee or other incidental tax or expense (excluding any applicable stamp duties) in respect of the issuance of such certificates, all of which taxes and expenses shall
be paid by the Company; provided, however, that the Company shall not be required to pay any tax that may be payable in respect of any transfer involved in the registration of any certificates for Warrant Shares or the Warrants in a name
other than that of the Holder or an Affiliate thereof. The Holder shall be responsible for all other tax liability that may arise as a result of holding or transferring this Warrant or receiving Warrant Shares upon exercise hereof. 

7. Replacement of Warrant. If this Warrant is mutilated, lost, stolen or destroyed, the Company shall issue or cause to be issued in exchange and
substitution for and upon cancellation hereof, or in lieu of and substitution for this Warrant, a New Warrant, but only upon receipt of evidence reasonably satisfactory to the Company of such loss, theft or destruction (in such case) and, in each
case, a customary and reasonable indemnity and surety bond, if requested by the Company. Applicants for a New Warrant under such circumstances shall also comply with such other reasonable regulations and procedures and pay such other reasonable
third-party costs as the Company may prescribe. If a New Warrant is requested as a result of a mutilation of this Warrant, then the Holder shall deliver such mutilated Warrant to the Company as a condition precedent to the Company’s obligation
to issue the New Warrant. 
 8. Reservation of Warrant Shares. The Company covenants that it will at all times while this Warrant is outstanding
reserve and keep available out of the aggregate of its authorized but unissued and otherwise unreserved Common Stock, solely for the purpose of enabling it to issue Warrant Shares upon exercise of this Warrant as herein provided, the number of
Warrant Shares that are initially issuable and deliverable upon the exercise of this entire Warrant, free from preemptive rights or any other contingent purchase rights of persons other than the Holder (taking into account the adjustments and
restrictions of Section 9). The Company covenants that all Warrant Shares so issuable and deliverable shall, upon issuance and the payment of the applicable Exercise Price in accordance with the terms hereof, be duly and
validly authorized, issued and fully paid and nonassessable. The Company will take all such action as may be reasonably necessary to assure that such shares of Common Stock may be issued as provided herein without violation of any applicable law or
regulation, or of any requirements of any securities exchange or automated quotation system upon which the Common Stock may be listed. 
 9. Certain
Adjustments. The number of Warrant Shares issuable upon exercise of this Warrant is subject to adjustment from time to time as set forth in this Section 9. 

(a) Stock Dividends and Splits. If the Company, at any time while this Warrant is outstanding, (i) pays a stock dividend on its
Common Stock or otherwise makes a distribution on any class of capital stock issued and outstanding on the Original Issue Date and in accordance with the terms of such stock on the Original Issue Date or as amended, that is payable in shares of
Common Stock, (ii) subdivides its outstanding shares of Common Stock into a larger number of shares of Common Stock, (iii) combines its outstanding shares of Common Stock into a smaller number of shares of Common Stock or (iv) issues
by reclassification of shares of capital stock any additional shares of Common Stock of the Company, then in each such case the number of Warrant Shares then underlying this Warrant shall be divided by a fraction, the numerator of which shall be the
number of shares of Common Stock outstanding immediately before such event and the denominator of which shall be the number of shares of Common Stock outstanding immediately after such event. Any adjustment made pursuant to clause (i) of this
paragraph shall become effective immediately after the record date for the determination of stockholders entitled to receive such dividend or distribution, provided, however, that if such record date shall have been fixed and such dividend is not
fully paid on the date fixed therefor, the number of Warrant Shares shall be recomputed accordingly as of the close of business on such record date and thereafter the Warrant Shares shall be adjusted pursuant to this paragraph as of the time of
actual payment of such dividends. Any adjustment pursuant to clause (ii) or (iii) of this paragraph shall become effective immediately after the effective date of such subdivision or combination. 

  
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 (b) Pro Rata Distributions. If the Company, at any time while this Warrant is outstanding,
distributes to all holders of Common Stock for no consideration (i) evidences of its indebtedness, (ii) any security (other than a distribution of Common Stock covered by the preceding paragraph), (iii) rights or warrants to subscribe for
or purchase any security, or (iv) cash or any other asset (in each case, “Distributed Property”), then, upon any exercise of this Warrant that occurs after the record date fixed for determination of stockholders entitled to
receive such distribution, the Holder shall be entitled to receive, in addition to the Warrant Shares otherwise issuable upon such exercise (if applicable), the Distributed Property that such Holder would have been entitled to receive in respect of
such number of Warrant Shares had the Holder been the record holder of such Warrant Shares immediately prior to such record date without regard to any limitation on exercise contained therein. 

(c) Fundamental Transactions. If, at any time while this Warrant is outstanding (i) the Company effects any merger or
consolidation of the Company with or into another Person, in which the Company is not the surviving entity or the stockholders of the Company immediately prior to such merger or consolidation do not own, directly or indirectly, at least 50% of the
voting power of the surviving entity immediately after such merger or consolidation, (ii) the Company effects any sale to another Person of all or substantially all of its assets in one transaction or a series of related transactions,
(iii) pursuant to any tender offer or exchange offer (whether by the Company or another Person), holders of capital stock who tender shares representing more than 50% of the voting power of the capital stock of the Company and the Company or
such other Person, as applicable, accepts such tender for payment, (iv) the Company consummates a stock purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with another Person whereby such other Person acquires more than the 50% of the voting power of the capital stock of the Company (except for any such transaction in which the
stockholders of the Company immediately prior to such transaction maintain, in substantially the same proportions, the voting power of such Person immediately after the transaction) or (v) the Company effects any reclassification of the Common
Stock or any compulsory share exchange pursuant to which the Common Stock is effectively converted into or exchanged for other securities, cash or property (other than as a result of a subdivision or combination of shares of Common Stock covered by
Section 9(a) above) (in any such case, a “Fundamental Transaction”), then following such Fundamental Transaction the Holder shall have the right to receive, upon exercise of this Warrant, the same amount
and kind of securities, cash or property as it 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 Warrant Shares then
issuable upon exercise in full of this Warrant without regard to any limitations on exercise contained herein (the “Alternate Consideration”). The Company shall not effect any Fundamental Transaction in which the Company is not the
surviving entity or the Alternate Consideration includes securities of another Person unless (i) the Alternate Consideration is solely cash and the Company provides for the simultaneous “cashless exercise” of this Warrant pursuant to
Section 10 below or (ii) prior to or simultaneously with the consummation thereof, any successor to the Company, surviving entity or other Person (including any purchaser of assets of the Company) shall assume the obligation to deliver to
the Holder, such Alternate Consideration as, in accordance with the foregoing provisions, the Holder may be entitled to receive, and the other obligations under this Warrant. The provisions of this paragraph (c) shall similarly apply to
subsequent transactions analogous of a Fundamental Transaction type. 
 (d) Calculations. All calculations under this
Section 9 shall be made to the nearest share. 
 (e) Notice of Adjustments. Upon the occurrence of each
adjustment pursuant to this Section 9, the Company at its expense will, at the written request of the Holder, promptly compute such adjustment, in good faith, in accordance with the terms of this Warrant and prepare a
certificate setting forth such adjustment, including a statement of the adjusted number or type of Warrant Shares or other securities issuable upon exercise of this Warrant (as applicable), describing the transactions giving rise to such adjustments
and showing in detail the facts upon which such adjustment is based. Upon written request, the Company will promptly deliver a copy of each such certificate to the Holder and to the Company’s transfer agent. 

(f) Notice of Corporate Events. If, while this Warrant is outstanding, the Company (i) declares a dividend or any other
distribution of cash, securities or other property in respect of its Common Stock, including, without limitation, any granting of rights or warrants to subscribe for or purchase any capital stock of the Company or any subsidiary,
(ii) authorizes or approves, enters into any agreement contemplating or solicits stockholder approval for any Fundamental Transaction or (iii) authorizes the voluntary dissolution, liquidation or winding up of the affairs of the Company,
then, except if such notice and the contents thereof shall be deemed to constitute material non-public information, the Company shall deliver to the Holder a notice of such transaction at least ten
(10) days prior to the applicable record or effective date on which a Person would need to hold Common Stock in order to participate in or vote with respect to such transaction; provided, however, that the failure to deliver such notice
or any defect therein shall not affect the validity of the corporate action required to be described in such notice. In addition, if while this Warrant is outstanding, the Company authorizes or approves, enters into any agreement contemplating or
solicits stockholder approval for any Fundamental Transaction contemplated by Section 9(c), other than a Fundamental Transaction 

  
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under clause (iii) of Section 9(c), the Company shall deliver to the Holder a notice of such Fundamental Transaction at least thirty (30) days prior to the date such Fundamental
Transaction is consummated. Holder agrees to maintain any information disclosed pursuant to this Section 9(f) in confidence until such information is publicly available, and shall comply with applicable law with respect to trading in the
Company’s securities following receipt any such information. 
 10. Payment of Exercise Price. Notwithstanding anything contained herein to the
contrary, the Holder may, in its sole discretion, satisfy its obligation to pay the Exercise Price through a “cashless exercise,” in which event the Company shall issue to the Holder the number of Warrant Shares determined as follows: 

X = Y [(A-B)/A] 

where: 
 “X” equals
the number of Warrant Shares to be issued to the Holder; 
 “Y” equals the total number of Warrant Shares with respect to which
this Warrant is then being exercised; 
 “A” equals the average of the Closing Sale Prices of the shares of Common Stock (as
reported by Bloomberg Financial Markets) for the five (5) consecutive Trading Days ending on the date immediately preceding the Exercise Date; and 

“B” equals the Exercise Price then in effect for the applicable Warrant Shares at the time of such exercise. 

For purposes of Rule 144 promulgated under the Securities Act, it is intended, understood and acknowledged that the Warrant Shares issued in a “cashless
exercise” transaction shall be deemed to have been acquired by the Holder, and the holding period for the Warrant Shares shall be deemed to have commenced, on the date this Warrant was originally issued (provided that the Commission continues
to take the position that such treatment is proper at the time of such exercise). Except as set forth in Section 5(b) (Buy-In remedy) and Section 12 (payment of cash in lieu of fractional shares), in
no event will the exercise of this Warrant be settled in cash. 
 11. Limitations on Exercise. 

(a) Notwithstanding anything to the contrary contained herein, the number of Warrant Shares that may be acquired by the Holder
upon any exercise of this Warrant (or otherwise in respect hereof) shall be limited to the extent necessary to ensure that, following such exercise (or other issuance), the total number of shares of Common Stock then beneficially owned by the Holder
and its Affiliates and any other Persons whose beneficial ownership of Common Stock would be aggregated with the Holder’s for purposes of Section 13(d) of the Exchange Act, does not exceed 9.99% of the total number of then issued and
outstanding shares of Common Stock (including for such purpose the shares of Common Stock issuable upon such exercise), it being acknowledged by the Holder that the Company is not representing to such Holder that such calculation is in compliance
with Section 13(d) of the Exchange Act and such Holder is solely responsible for any schedules required to be filed in accordance therewith. To the extent that the limitation contained in this Section 11(a) applies,
the determination of whether this Warrant is exercisable (in relation to other securities owned by such Holder) and of which a portion of this Warrant is exercisable shall be in the sole discretion of the Holder, and the submission of a Notice of
Exercise shall be deemed to be the Holder’s determination of whether this Warrant is exercisable (in relation to other securities owned by such Holder) and of which portion of this Warrant is exercisable, in each case subject to such aggregate
percentage limitation, and the Company shall have no obligation to verify or confirm the accuracy of such determination. In addition, a determination under this Section 11(a) as to any group status shall be determined in
accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated thereunder. For purposes of this Section 11(a), in determining the number of outstanding shares of Common Stock, the Holder
may rely on the number of outstanding shares of Common Stock as reflected in (x) the Company’s most recent Form 10-Q or Form 10-K, as the case may be,
(y) a more recent public announcement by the Company or (z) any other notice by the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding. Upon the written request of the Holder, the Company shall,
within three (3) Trading Days, confirm orally and in writing to such Holder the number of shares of Common Stock then outstanding. By written notice to the Company, which will not be effective until the sixty-first (61st) day after such notice is delivered to the Company, the Holder may waive the provisions of this Section 11(a) or increase the beneficial ownership limitation to such
percentage of the number of shares of the Common Stock outstanding immediately after giving effect to the issuance of shares of Common Stock upon exercise of this Warrant as the Holder shall determine, in its sole discretion, subject to
Section 11(b), and the provisions of this Section 11(a) shall continue to apply. Upon such a change by a Holder of the beneficial ownership limitation from such 9.99% limitation to such other
percentage limitation, the beneficial ownership limitation may not be further waived or increased by such Holder without first providing the minimum notice required by this Section 11(a). Notwithstanding the foregoing, at
any time following notice of a Fundamental Transaction under 

  
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Section 9(f)(ii) with respect to a Section 9(c)(iii) Fundamental Transaction, the Holder may waive and/or change the beneficial ownership
limitation effective immediately upon written notice to the Company and may reinstitute a beneficial ownership limitation at any time thereafter effective immediately upon written notice to the Company. 

(b) Notwithstanding anything to the contrary contained herein, including Section 11(a), the Company shall not effect
any exercise of this Warrant, and the Holder shall not be entitled to exercise this Warrant for a number of Warrant Shares in excess of that number of Warrant Shares which, upon giving effect to such exercise, would cause (i) the aggregate
number of shares of Common Stock beneficially owned by the Holder and its Affiliates and any other Persons whose beneficial ownership of Common Stock would be aggregated with the Holder’s for purposes of Section 13(d) of the Exchange Act,
to exceed 19.99% of the total number of issued and outstanding shares of Common Stock of the Company following such exercise, or (ii) the combined voting power of the securities of the Company beneficially owned by the Holder and its Affiliates
and any other Persons whose beneficial ownership of Common Stock would be aggregated with the Holder’s for purposes of Section 13(d) of the Exchange Act to exceed 19.99% of the combined voting power of all of the securities of the Company
then outstanding following such exercise. For purposes of this Section 11(b), the aggregate number of shares of Common Stock or voting securities beneficially owned by the Holder and its Affiliates and any other Persons
whose beneficial ownership of Common Stock would be aggregated with the Holder’s for purposes of Section 13(d) of the Exchange Act shall include the shares of Common Stock issuable upon the exercise of this Warrant with respect to which
such determination is being made, but shall exclude the number of shares of Common Stock which would be issuable upon (x) exercise of the remaining unexercised and non-cancelled portion of this Warrant by
the Holder and (y) exercise or conversion of the unexercised, non-converted or non-cancelled portion of any other securities of the Company that do not have voting
power (including without limitation any securities of the Company which would entitle the holder thereof to acquire at any time Common Stock, including without limitation any debt, preferred stock, right, option, warrant or other instrument that is
at any time convertible into or exercisable or exchangeable for, or otherwise entitles the holder thereof to receive, Common Stock), is subject to a limitation on conversion or exercise analogous to the limitation contained herein and is
beneficially owned by the Holder or any of its Affiliates and other Persons whose beneficial ownership of Common Stock would be aggregated with the Holder’s for purposes of Section 13(d) of the Exchange Act. 

(c) This Section 11 shall not restrict the number of shares of Common Stock which a Holder may receive or
beneficially own in order to determine the amount of securities or other consideration that such Holder may receive in the event of a Fundamental Transaction as contemplated in Section 9 of this Warrant. 

12. No Fractional Shares. No fractional Warrant Shares will be issued in connection with any exercise of this Warrant. In lieu of any fractional shares
that would otherwise be issuable, the number of Warrant Shares to be issued shall be rounded down to the next whole number and the Company shall pay the Holder in cash the fair market value (based on the Closing Sale Price) for any such fractional
shares. 
 13. Notices. Any and all notices or other communications or deliveries hereunder (including, without limitation, any Exercise Notice)
shall be in writing and shall be deemed given and effective on the earliest of (i) the date of transmission, if such notice or communication is delivered via facsimile or confirmed e-mail at the facsimile
number or e-mail address specified below prior to 5:30 P.M., New York City time, on a Trading Day, (ii) the next Trading Day after the date of transmission, if such notice or communication is
delivered via facsimile or confirmed e-mail at the facsimile number or e-mail address specified below on a day that is not a Trading Day or later than 5:30 P.M., New
York City time, on any Trading Day, (iii) the Trading Day following the date of mailing, if sent by nationally recognized overnight courier service specifying next business day delivery, or (iv) upon actual receipt by the Person to whom
such notice is required to be given, if by hand delivery. 
 14. Warrant Agent. The Company shall initially serve as warrant agent under this
Warrant. Upon thirty (30) days’ notice to the Holder, the Company may appoint a new warrant agent. Any corporation into which the Company or any new warrant agent may be merged or any corporation resulting from any consolidation to which
the Company or any new warrant agent shall be a party or any corporation to which the Company or any new warrant agent transfers substantially all of its corporate trust or shareholders services business shall be a successor warrant agent under this
Warrant without any further act. Any such successor warrant agent shall promptly cause notice of its succession as warrant agent to be mailed (by first class mail, postage prepaid) to the Holder at the Holder’s last address as shown on the
Warrant Register. 
 15. Miscellaneous. 

(a) No Rights as a Stockholder. The Holder, solely in such Person’s capacity as a holder of this Warrant, shall not be entitled to
vote or receive dividends or be deemed the holder of share capital of the Company for any purpose, nor shall anything contained in this Warrant be construed to confer upon the Holder, solely in such Person’s capacity as the Holder of this
Warrant, any of the rights of a stockholder of the Company or any right to vote, give or withhold consent to any corporate action 

  
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(whether any reorganization, issue of stock, reclassification of stock, consolidation, merger, amalgamation, conveyance or otherwise), receive notice of meetings, receive dividends or
subscription rights, or otherwise, prior to the issuance to the Holder of the Warrant Shares which such Person is then entitled to receive upon the due exercise of this Warrant. In addition, nothing contained in this Warrant shall be construed as
imposing any liabilities on the Holder to purchase any securities (upon exercise of this Warrant or otherwise) or as a stockholder of the Company, whether such liabilities are asserted by the Company or by creditors of the Company. 

(b) Authorized Shares. 

(i) Except and to the extent as waived or consented to by the Holder, the Company shall not by any action, including, without limitation,
amending its certificate or articles of incorporation or through any reorganization, transfer of assets, consolidation, merger, dissolution, issue or sale of securities or any other voluntary action, avoid or seek to avoid the observance or
performance of any of the terms of this Warrant, but will at all times in good faith assist in the carrying out of all such terms and in the taking of all such actions as may be necessary or appropriate to protect the rights of Holder as set forth
in this Warrant against impairment. Without limiting the generality of the foregoing, the Company will (a) not increase the par value of any Warrant Shares above the amount payable therefor upon such exercise immediately prior to such increase
in par value, (b) take all such action as may be necessary or appropriate in order that the Company may validly and legally issue fully paid and nonassessable Warrant Shares upon the exercise of this Warrant, and (c) use commercially
reasonable efforts to obtain all such authorizations, exemptions or consents from any public regulatory body having jurisdiction thereof as may be necessary to enable the Company to perform its obligations under this Warrant. 

(ii) Before taking any action which would result in an adjustment in the number of Warrant Shares for which this Warrant is exercisable or in
the Exercise Price, the Company shall obtain all such authorizations or exemptions thereof, or consents thereto, as may be necessary from any public regulatory body or bodies having jurisdiction thereof. 

(c) Successors and Assigns. Subject to the restrictions on transfer set forth in this Warrant and the restrictions on transfer set
forth in this Warrant and compliance with applicable securities laws, this Warrant may be assigned by the Holder. This Warrant may not be assigned by the Company without the written consent of the Holder except to a successor in the event of a
Fundamental Transaction. This Warrant shall be binding on and inure to the benefit of the Company and the Holder and their respective successors and assigns. Subject to the preceding sentence, nothing in this Warrant shall be construed to give to
any Person other than the Company and the Holder any legal or equitable right, remedy or cause of action under this Warrant. This Warrant may be amended only in writing signed by the Company and the Holder, or their successors and assigns. 

(d) Amendment and Waiver. Except as otherwise provided herein, the provisions of the Warrants may be amended and the Company may take
any action herein prohibited, or omit to perform any act herein required to be performed by it, only if the Company has obtained the written consent of the Holders of Warrants representing no less than a majority of the Warrant Shares obtainable
upon exercise of the Warrants then outstanding. 
 (e) Acceptance. Receipt of this Warrant by the Holder shall constitute acceptance
of and agreement to all of the terms and conditions contained herein. 
 (f) Governing Law; Jurisdiction. ALL QUESTIONS CONCERNING
THE CONSTRUCTION, VALIDITY, ENFORCEMENT AND INTERPRETATION OF THIS WARRANT SHALL BE GOVERNED BY AND CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF LAW THEREOF. EACH OF THE
COMPANY AND THE HOLDER HEREBY IRREVOCABLY SUBMITS TO THE EXCLUSIVE JURISDICTION OF THE STATE AND FEDERAL COURTS SITTING IN THE CITY OF NEW YORK, BOROUGH OF MANHATTAN, FOR THE ADJUDICATION OF ANY DISPUTE HEREUNDER OR IN CONNECTION HEREWITH OR WITH
ANY TRANSACTION CONTEMPLATED HEREBY OR DISCUSSED HEREIN (INCLUDING WITH RESPECT TO THE ENFORCEMENT OF ANY OF THE TRANSACTION DOCUMENTS), AND HEREBY IRREVOCABLY WAIVES, AND AGREES NOT TO ASSERT IN ANY SUIT, ACTION OR PROCEEDING, ANY CLAIM THAT IT IS
NOT PERSONALLY SUBJECT TO THE JURISDICTION OF ANY SUCH COURT. EACH OF THE COMPANY AND THE HOLDER HEREBY IRREVOCABLY WAIVES PERSONAL SERVICE OF PROCESS AND CONSENTS TO PROCESS BEING SERVED IN ANY SUCH SUIT, ACTION OR PROCEEDING BY MAILING A COPY
THEREOF VIA REGISTERED OR CERTIFIED MAIL OR OVERNIGHT DELIVERY (WITH EVIDENCE OF DELIVERY) TO SUCH PERSON AT THE ADDRESS IN EFFECT FOR NOTICES TO IT AND AGREES THAT SUCH SERVICE SHALL CONSTITUTE GOOD AND SUFFICIENT SERVICE OF PROCESS AND NOTICE
THEREOF. NOTHING CONTAINED HEREIN SHALL BE DEEMED TO LIMIT IN ANY WAY ANY RIGHT TO SERVE PROCESS IN ANY MANNER PERMITTED BY LAW. EACH OF THE COMPANY AND THE HOLDER HEREBY WAIVES ALL RIGHTS TO A TRIAL BY JURY. 

  
 7 

 (g) Headings. The headings herein are for convenience only, do not constitute a part of
this Warrant and shall not be deemed to limit or affect any of the provisions hereof. 
 (h) Severability. In case any one or more of
the provisions of this Warrant shall be invalid or unenforceable in any respect, the validity and enforceability of the remaining terms and provisions of this Warrant shall not in any way be affected or impaired thereby, and the Company and the
Holder will attempt in good faith to agree upon a valid and enforceable provision which shall be a commercially reasonable substitute therefor, and upon so agreeing, shall incorporate such substitute provision in this Warrant. 

[REMAINDER OF PAGE INTENTIONALLY LEFT BLANK] 

  
 8 

 IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed by its authorized officer as of the
date first indicated above. 
  

			
	SYNDAX PHARMACEUTICALS, INC.

  

			
	By:	 	  

	Name:
	Title:

  
 9 

 SCHEDULE 1 

FORM OF EXERCISE NOTICE 
 [To be
executed by the Holder to purchase shares of Common Stock under the Warrant] 
 Ladies and Gentlemen: 

 

	(1)	The undersigned is the Holder of Warrant No.      (the “Warrant”) issued by Syndax Therapeutics, Inc., a Delaware corporation (the “Company”). Capitalized
terms used herein and not otherwise defined herein have the respective meanings set forth in the Warrant. 

  

	(2)	The undersigned hereby exercises its right to purchase Warrant Shares pursuant to the Warrant. 

  

	(3)	The Holder intends that payment of the Exercise Price shall be made as (check one): 

  

	 	☐	Cash Exercise 

  

	 	☐	“Cashless Exercise” under Section 10 of the Warrant 

  

	(4)	If the Holder has elected a Cash Exercise, the Holder shall pay the sum of $                in immediately available funds to the Company
in accordance with the terms of the Warrant. 

  

	(5)	Pursuant to this Exercise Notice, the Company shall deliver to the Holder Warrant Shares determined in accordance with the terms of the Warrant. 

 

	(6)	By its delivery of this Exercise Notice, the undersigned represents and warrants to the Company that in giving effect to the exercise evidenced hereby the Holder will not beneficially own in excess of the number of
shares of Common Stock (as determined in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended) permitted to be owned under Section 11(a) or Section 11(b), as
applicable, of the Warrant to which this notice relates. 

  

			
	Dated:	 	  

		
	Name of Holder:	 	  

		
	By:	 	  

	Name:      	 	  

	Title:	 	  

 (Signature must conform in all respects to name of Holder as specified on the face of the Warrant)EX-10.1

 Exhibit 10.1 

June 18, 2018 
 Briggs W. Morrison, M.D. 

Chief Executive Officer 
 Syndax Pharmaceuticals, Inc. 

Building D, Floor 3 
 35 Gatehouse Drive 

Waltham, Massachusetts 02451 
 Re: 3(a)(9)
Exchange Agreement
 Dear Dr. Morrison: 

This letter agreement (the “Agreement”) confirms the agreement of Syndax Pharmaceuticals, Inc., a Delaware corporation
(the “Company”), and the holders of the Common Stock listed on Schedule I attached hereto (each a “Common Stock Holder” and collectively, the “Common Stock Holders”),
pursuant to which the Common Stock Holders have agreed to exchange an aggregate of 2,000,000 shares (the “Shares”) of Common Stock, par value $0.0001 per share (the “Common Stock”), of the Company
beneficially owned by the Common Stock Holders for one or more Common Stock Warrants in the form attached hereto as Exhibit A (each a “Warrant”) to purchase an aggregate of 2,000,000 shares of Common Stock (the
“Warrant Shares”) of the Company, pursuant to Section 3(a)(9) of the Securities Act of 1933, as amended (the “Securities Act”), on terms specified below. 

(1) No later than the close of business on the first business day after the date hereof (the “Closing Date”) and
subject to the satisfaction or waiver of the conditions set forth herein, the Common Stock Holders shall exchange the Shares for the Warrants representing the Warrant Shares (the “Exchange”) in the respective amounts listed
on Schedule I. On the Closing Date: (a) the Company and the Common Stock Holders shall jointly and irrevocably instruct the Transfer Agent to cancel the direct registration book-entry statements from the Transfer Agent evidencing the
Shares; and (b) the Company shall issue and deliver to the Common Stock Holders the Warrants representing the Warrant Shares, in the amounts and registered in the names set forth on Schedule I. 

(2) The Company represents and warrants to each Common Stock Holder as follows: 

(a) Neither the Company nor any of its affiliates nor any person acting on behalf of or for the benefit of any of the forgoing,
has paid or given, or agreed to pay or give, directly or indirectly, any commission or other remuneration (within the meaning of Section 3(a)(9) of the Securities Act and the rules and regulations of the Commission promulgated thereunder) for
soliciting the Exchange. Assuming the representations and warranties of the Common Stock Holders contained herein are true and complete, the Exchange will qualify for the registration exemption contained in Section 3(a)(9) of the Securities
Act. 
 (b) It has the requisite corporate power and authority and power to enter into this Agreement and to consummate the
Exchange and such transactions shall not contravene any contractual, regulatory, statutory or other obligation or restriction applicable to the Company. 

(c) It has reserved a sufficient number of shares of Common Stock as may be necessary to fully permit the exercise of the
Warrants and the issuance of the Warrant Shares, without regard to any beneficial ownership limits set forth in the Warrant. 
 (3) Each
Common Stock Holder, as to itself only, represents and warrants to the Company as follows: 
 (a) It has the requisite power
and authority to enter into this Agreement and consummate the Exchange. 

 (b) It is the record and beneficial owner of, and has valid and marketable title
to, the Shares being exchanged by it pursuant to this Agreement, free and clear of any lien, pledge, restriction or other encumbrance (other than restrictions arising pursuant to applicable securities laws), and has the absolute and unrestricted
right, power and capacity to surrender and exchange the Shares being exchanged by it pursuant to this Agreement, free and clear of any lien, pledge, restriction or other encumbrance. It is not a party to or bound by, and the Shares being exchanged
by it pursuant to this Agreement are not subject to, any agreement, understanding or other arrangement (i) granting any option, warrant or right of first refusal with respect to such Shares to any person, (ii) restricting its right to
surrender and exchange such Shares as contemplated by this Agreement, or (iii) restricting any other of its rights with respect to such Shares. 

(c) Neither it nor any of its affiliates nor any person acting on behalf of or for the benefit of any of the forgoing, has paid
or given, or agreed to pay or give, directly or indirectly, any commission or other remuneration (within the meaning of Section 3(a)(9) and the rules and regulations of the Commission promulgated thereunder) for soliciting the Exchange. 

(4) This agreement, and any action or proceeding arising out of or relating to this agreement, shall be exclusively governed by the laws of
the State of New York. 
 (5) In the event that any part of this agreement is declared by any court or other judicial or administrative body
to be null, void or unenforceable, said provision shall survive to the extent it is not so declared, and all of the other provisions of this agreement shall remain in full force and effect. In such an event, the Common Stock Holders and the Company
shall endeavor in good faith negotiations to modify this agreement so as to affect the original intent of the parties as closely as possible. 

(6) This Agreement may be executed in two or more counterparts, each of which shall constitute an original, but all of which, when taken
together, shall constitute but one instrument, and shall become effective when one or more counterparts have been signed by each party hereto and delivered to the other parties. 

[SIGNATURE PAGE FOLLOWS] 

  
 2 

 Please sign to acknowledge agreement with the above terms and return to the undersigned. 

 

			
	Common Stockholder:
	
	Biotechnology Value Fund, L.P.
	
	By: BVF Partners L.P., General Partner
		
	By:	 	 BVF, Inc., General Partner

		
	By:	 	 /s/ Mark Lampert

	Name:	 	Mark Lampert
	Title:	 	President
	
	Biotechnology Value Fund II, L.P.
	
	By: BVF Partners L.P., General Partner
		
	By:	 	 BVF, Inc., General Partner

		
	By:	 	 /s/ Mark Lampert

	Name:	 	Mark Lampert
	Title:	 	President
	
	Biotechnology Value Trading Fund OS, L.P.
	
	By: BVF Partners OS, Ltd., General Partner
	
	By: BVF Partners L.P., Sole Member
		
	By:	 	 BVF, Inc. General Partner

		
	By:	 	 /s/ Mark Lampert

	Name:	 	Mark Lampert
	Title:	 	President

 Acknowledged and agreed to: 

Syndax Pharmaceuticals, Inc. 
  

			
	By:	 	 /s/ Luke J. Albrecht

		 	Luke J. Albrecht
		 	Vice President and General Counsel

 SCHEDULE I 
  

									
	 Common Stock Holder
	  	Shares of Common Stock
to be Exchanged	 	  	Warrant Shares	 
	 Biotechnology Value Fund, L.P.
	  	 	1,105,391	 	  	 	1,105,391	 
	 Biotechnology Value Fund II, L.P.
	  	 	705,863	 	  	 	705,863	 
	 Biotechnology Value Trading Fund OS, L.P.
	  	 	188,746	 	  	 	188,746	 
		  	  
	  
	 	  	  
	  
	 
	 Total
	  	 	2,000,000	 	  	 	2,000,000	 
		  	  
	  
	 	  	  
	  
	 

 Exhibit A 

Form of Warrant to Purchase Common Stock

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