Document:

Exhibit 4.3

 

WARRANT EXCHANGE AGREEMENT

 

This WARRANT
EXCHANGE AGREEMENT dated as of October 6, 2021, is by and between LifeSci Acquisition II Corp. a Delaware corporation (the “Company”)
LifeSci Holdings LLC, a Delaware limited liability company (“Holder”).

 

WHEREAS,
on November 24, 2020, the Company entered into a Private Warrant Agreement (the “Warrant Agreement”) by and
between the Company and the Holder;

 

WHEREAS, simultaneous with the closing
of the Company’s initial public offering, the Company sold warrants (the “Private Warrants”) to purchase 3,146,453
shares of the Company’s common stock, par value $0.0001 per share (“Common Stock”) at a price of $11.50 per
share;

 

WHEREAS, the Company and Holder
entered into that certain Support Agreement dated as of May 6, 2021 (the “Support Agreement”) with Science 37,
Inc., a Delaware corporation (“Science 37”), pursuant to which Holder agreed to, among other things, amend the
Warrant Agreement or enter into such other agreement that provides for the Private Warrants to convert into the right to receive
3,146,453 shares of Common Stock, in the aggregate, immediately prior to the effective time of the Merger (as defined below);
and

 

WHEREAS, the Support Agreement was entered
into in connection with that certain Merger Agreement dated as of May 6, 2021 (“Merger Agreement”), by and among the
Company, Science 37, and LifeSci Acquisition II Merger Sub, Inc., a Delaware corporation and wholly-owned subsidiary of the Parent (“Merger
Sub”), pursuant to which, among other things Merger Sub will merge with and into Science 37, with Science 37 surviving as the
surviving corporation and a wholly owned subsidiary of the Parent (“Merger”)

 

NOW, THEREFORE, for good and valuable
consideration, the receipt and sufficiency of which is hereby acknowledged, the parties agree as follows:

 

1.                 
The Holder is the registered owner of 3,146,453 Private Warrants. Contingent upon consummation of the Merger, and effective as
of immediately prior to the effective time of the Merger, the Holder is returning the Private Warrants to the Company for cancellation
and the Company is issuing to the Holder an equal number of shares of Common Stock.

 

2.                 
The Company and the Holder have the full legal capacity to enter into this Agreement on their own behalf.

 

3.                 
No further authorization or approval is required on the part of the Company or Holder to enter into this Agreement and carry out
the provisions hereof.

 

[Intentionally Blank. Signature
Page Follows.]

     

     

    

 

IN WITNESS WHEREOF, the parties hereto
have caused this Agreement to be duly executed as of the date first above written.

 

	 	LIFESCI ACQUISITION
    II CORP.	 
	 	 	 	 	 
	 	By:	 	/s/ Andrew McDonald	 
	 	 	 	Name: Andrew McDonald	 
	 	 	 	Title: Chief Executive Officer	 

 

	Holder:	 
	 	 	 	 
	Accepted and Agreed:	 
	 	 	 	 
	LIFESCI HOLDINGS,
    LLC	 
	 	 	 	 
	 	 	 	 
	By:	 	/s/ Andrew McDonald	 
	Name: Andrew McDonald	 
	Title: Manager	 
	 	 	 	 
	 	 	 	 
	By:	 	/s/ David Dobkin	 
	Name: David Dobkin	 
	Title: Manager	 
	 	 	 	 
	 	 	 	 
	By:	 	/s/ Michael Rice	 
	Name: Michael Rice	 
	Title: Manager	 

 

 

[Signature Page to Warrant
Exchange Agreement]

 

2Exhibit 10.18

 

SPONSOR LOCK-UP AGREEMENT

 

THIS
SPONSOR LOCK-UP AGREEMENT (this “Agreement”) is dated as of May 6, 2021, by and between the undersigned (the “Holder”)
and LifeSci Acquisition II Corp., a Delaware corporation (“Parent”). Capitalized terms used and not otherwise defined
herein shall have the meanings given such terms in the Merger Agreement (as defined below).

 

BACKGROUND

 

A.                
Parent, LifeSci Acquisition II Merger Sub, Inc. a Delaware corporation and wholly owned subsidiary of Parent, and Science 37, Inc.,
a Delaware corporation (the “Company”), entered into a Merger Agreement dated as of May 6, 2021 (the “Merger
Agreement”).

 

B.                 
Pursuant to the Merger Agreement, Parent will become the 100% stockholder of the Company (the “Transaction”).

 

C.                 
The Holder is the record and/or beneficial owner of (i) certain shares Parent Common Stock and (ii) certain Parent Warrants.

 

D.                
As a condition of, and as a material inducement for the Company to enter into and consummate the transactions contemplated by the
Merger Agreement, the Holder has agreed to execute and deliver this Agreement.

 

NOW, THEREFORE,
for and in consideration of the mutual covenants and agreements set forth herein, and other good and valuable consideration, the receipt
and sufficiency of which is hereby acknowledged, the parties, intending to be legally bound, agree as follows:

 

AGREEMENT

 

		1.	Lock-Up.

 

(a)               
Subject to Section 1(e), during the Lock-up Period (as defined below), the Holder irrevocably agrees that it, he
or she will not (i) offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any of the Lock-up Shares (as
defined below), (ii) enter into a transaction that would have the same effect, or enter into any swap, hedge or other arrangement that
transfers, in whole or in part, any of the economic consequences of ownership of such Lock-up Shares, whether any such transaction described
in clause (i) or (ii) above is to be settled by delivery of any such Lock-up Shares, in cash or otherwise, (iii) publicly disclose the
intention to make any offer, sale, pledge or disposition, or to enter into any transaction, swap, hedge or other arrangement or (iv) engage
in any Short Sales (as defined below) with respect to any security of Parent; provided, for the avoidance of doubt, that nothing in this
Agreement shall restrict the Holder’s right to cause the Company to file and cause to become effective a registration statement
with the U.S. Securities and Exchange Commission (the “SEC”) naming such Holder as a selling securityholder (and to
make any required disclosures in respect thereof), if applicable.

 

(b)               
In furtherance of the foregoing, Parent will (i) place an irrevocable stop order on all Lock-up Shares, including those
which may be covered by a registration statement, and (ii) notify Parent’s transfer agent in writing of the stop order and the restrictions
on such Lock-up Shares under this Agreement and direct Parent’s transfer agent not to process any attempts by the Holder to resell
or transfer any Lock-up Shares, except in compliance with this Agreement.

 

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(c)               
For purposes hereof, “Short Sales” include, without limitation, all “short sales” as defined
in Rule 200 promulgated under Regulation SHO under the Securities Exchange Act of 1934, as amended (the “Exchange Act”),
and all types of direct and indirect stock pledges, forward sale contracts, options, puts, calls, swaps and similar arrangements (including
on a total return basis), and sales and other transactions through non-U.S. broker dealers or foreign regulated brokers.

 

(d)               
For purpose of this Agreement, the “Lock-up Period” means, with respect to the Lock-up Shares, the period
commencing on the Closing Date and ending on the date that is 180 calendar days thereafter.

 

(e)               
Notwithstanding the provisions set forth in this Section 1, the restrictions set forth herein shall not apply to:
(i) transfers or distributions to the Holder’s current or former general or limited partners, managers or members, stockholders,
other equityholders or other direct or indirect affiliates (within the meaning of Rule 405 under the Securities Act of 1933, as amended)
or to the estates of any of the foregoing; (ii) transfers by operation of law; (iii) the establishment of a trading plan pursuant to
Rule 10b5-1 under the Exchange Act for the transfer of Lock-up Shares; provided, that such plan does not pro- vide for the transfer
of Lock-up Shares during the Lock-up Period; (iv) gifts to a charitable organization; (v) transfers in connection with any bona fide
mortgage, encumbrance or pledge to a financial institution in connection with any bona fide loan or debt transaction or enforcement thereunder;
(vi) transfers to Parent or the Company; (vii) transfers to (A) Parent’s or the Company’s officers or directors or (B) any
affiliates or family members of Parent’s or the Company’s officers or directors; (viii) the exercise of warrants to purchase
shares of Parent Common Stock and any related transfer of shares of Parent Common Stock in connection therewith (A) deemed to occur upon
the “cashless” or “net” exercise of such warrants or (B) for the purpose of paying the exercise price of such
warrants or for paying taxes due as a result of the exercise of such warrants or the vesting of such warrants, it being understood that
all shares of Parent Common Stock received upon such exercise or transfer will remain subject to the restrictions of this Agreement during
the Lock-up Period or (ix) transactions relating to shares of Parent Common Stock acquired in open market transactions, in each of clauses
(i), (ii), (iii), (iv) and (vii), where such transferee agrees to be bound by the terms of this Agreement.

 

(f)                
In addition, after the Closing Date, if there is a Change of Control, then upon the consummation of such Change of Control,
all Lock-up Shares shall be automatically released from the restrictions contained herein. A “Change of Control” means:
(a) the sale of all or substantially all of the consolidated assets of Parent and its Subsidiaries to a third-party purchaser; (b) a sale
resulting in no less than a majority of the voting power of the Parent being held by any Person that did not own a majority of the voting
power prior to such sale; or (c) a merger, consolidation, recapitalization or reorganization of Parent with or into a third-party purchaser
that results in the inability of the pre-transaction equity holders of Parent to designate or elect a majority of the board of directors
(or its equivalent) of the resulting entity or its parent company.

 

2.                  
Representations and Warranties. Each party hereto, by its respective execution and delivery of this Agreement, hereby
represents and warrants to the other party hereto and to all third party beneficiaries of this Agreement that (a) such party has the full
right, capacity and authority to enter into, deliver and perform such party’s respective obligations under this Agreement, (b) this
Agreement has been duly executed and delivered by such party and is the binding and enforceable obligation of such party, enforceable
against such party in accordance with the terms of this Agreement, and (c) the execution, delivery and performance of such party’s
obligations under this Agreement will not conflict with or breach the terms of any other agreement, contract, commitment or understanding
to which such party is a party or to which the assets or securities of such party are bound.

 

    	 	2	 

     

    

3.                  
Beneficial Ownership. The Holder hereby represents and warrants that it does not beneficially own, directly or through
its nominees (as determined in accordance with Section 13(d) of the Exchange Act, and the rules and regulations promulgated thereunder),
any shares of capital stock of Parent, or any economic interest in or derivative of such stock, other than those securities specified
on the signature page hereto. For purposes of this Agreement, (i) the shares of Parent Common Stock and (ii) Parent Warrants beneficially
owned by the Holder as specified on the signature page hereto are collectively referred to as the “Lock-up Shares.”

 

4.                  
No Additional Fees/Payment. Other than the consideration specifically referenced herein, the parties hereto agree
that no fee, payment or additional consideration in any form has been or will be paid to the Holder in connection with this Agreement.

 

5.                   Notices.
All notices and other communications to be given or made hereunder shall, unless otherwise specified herein, be in writing and shall
be deemed to have been duly given or made on the date of receipt by the recipient thereof if received prior to 5:00 p.m. Eastern
Time in the place of receipt and such day is a Business Day (or otherwise on the next succeeding Business Day) if (a) served by
personal delivery or by a nationally recognized overnight courier service upon the party for whom it is intended, (b)  delivered
by registered or certified mail, return receipt requested, or (c) sent by email. Such communications shall be sent to the respective
parties at the following street addresses or email addresses or at such other street address or email address for a party as shall
be specified for such purpose in a notice given in accordance with this Section 5:

 

		(a)	If to Parent, to:

 

LifeSci Acquisition II Corp.

250 West 55th Street,
#3401

New York, NY 10019

Attention: Andrew McDonald

E-mail: andrew@lifesciacquisition.com

 

with a copy to (which shall not constitute notice):

 

Loeb & Loeb

345 Park Avenue, 19th Floor New York, NY 10154

Attention: Mitchell S. Nussbaum, Esq.

E-mail: mnussbaum@loeb.com

 

		(b)	If to the Holder, to the addresses set forth on the Holder’s
signature page hereto.

 

or to such other address as any party
may have furnished to the others in writing in accordance herewith.

 

6.                  
Enumeration and Headings. The enumeration and headings contained in this Agreement are for convenience of reference
only and shall not control or affect the meaning or construction of any of the provisions of this Agreement.

 

7.                  
Counterparts. This Agreement may be executed in any number of counterparts, each such counterpart being deemed to
be an original instrument, and all such counterparts shall together constitute the same agreement. The exchange of copies of this Agreement
and signature pages by email in .pdf or .tif

    	 	3	 

     

    

format (and including, without limitation,
any electronic signature complying with the U.S. ESIGN Act of 2000, e.g., www.docusign.com), or by any other electronic means intended
to preserve the original graphic and pictorial appearance of a document, or by combination of such means, shall constitute effective execution
and delivery of this Agreement as to the parties hereto and may be used in lieu of the original Agreement for all purposes. Such execution
and delivery shall be considered valid, binding and effective for all purposes.

 

8.                  
Successors and Assigns. This Agreement shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and permitted assigns. No party hereto shall be permitted to assign any of such party’s rights or delegate
any of its obligations under this Agreement, in whole or in part, by operation of Law or otherwise, without the prior written consent
of the other party hereto, and any attempted or purported assignment or delegation in violation of this Section 8 shall be null
and void.

 

9.                  
Severability. The provisions of this Agreement shall be deemed severable and the illegality, invalidity or unenforceability
of any provision shall not affect the legality, validity or enforceability of the other provisions of this Agreement. If any provision
of this Agreement, or the application of such provision to any Person or any circumstance, is illegal, invalid or unenforceable, (a) a
suitable and equitable provision to be negotiated by the parties hereto, each acting reasonably and in good faith, shall be substituted
therefor in order to carry out, so far as may be legal, valid and enforceable, the intent and purpose of such legal, invalid or unenforceable
provision, and (b) the remainder of this Agreement and the application of such provision to other Persons or circumstances shall not be
affected by such illegality, invalidity or unenforceability, nor shall such illegality, invalidity or unenforceability affect the legality,
validity or enforceability of such provision, or the application of such provision, in any other jurisdiction.

 

10.                
Amendment. This Agreement may be amended or modified by written agreement executed by each of the parties hereto.

 

11.                
Further Assurances. Each party hereto shall do and perform, or cause to be done and performed, all such further acts
and things, and shall execute and deliver all such other agreements, certificates, instruments and documents, as any other party hereto
may reasonably request in order to carry out the intent and accomplish the purposes of this Agreement and the consummation of the transactions
contemplated hereby.

 

12.                
No Strict Construction. The language used in this Agreement will be deemed to be the language chosen by the parties
hereto to express their mutual intent, and no rules of strict construction will be applied against any party hereto.

 

13.                
Governing Law. This Agreement, and any claims or Proceedings arising out of this Agreement or the subject matter
hereof (whether at law or equity, in contract or in tort or otherwise), shall be governed by and construed in accordance with the laws
of the State of Delaware without regard to the conflict of law principles thereof (or any other jurisdiction) to the extent that such
principles would direct a matter to another jurisdiction.

 

14.                
Controlling Agreement. To the extent the terms of this Agreement (as amended, supplemented, restated or otherwise
modified from time to time) directly conflicts with a provision in the Merger Agreement, the terms of this Agreement shall control.

 

 

[Signature Page Follows]

    	 	4	 

     

    

 

IN
WITNESS WHEREOF, the parties hereto have caused this Lock-up Agreement to be duly executed by their respective authorized signatories
as of the date first indicated above.

 

 

	 	LIFESCI ACQUISITION
                                           II CORP.	 
	 	 	 	 
	 	 	 	 
		By:	/s/
                                            Andrew McDonald	 
	 	 	Name: Andrew McDonald
	 	 	Title: Chief Executive Officer

 

 

    [Signature Page to Sponsor Lock-Up Agreement]

     

    

 

IN WITNESS WHEREOF, the parties
hereto have caused this Lock-up Agreement to be duly executed by their respective authorized signatories as of the date first indicated
above.

 

 

	 	HOLDER	 
	 	 	 
	 	LIFESCI
                                            HOLDINGS LLC 	 
	 	 	 	 
	 	 	 	 
		By:	/s/
                                            Andrew McDonald	 
	 	 	Name:
                                            Andrew McDonald
	 	 	Title:
                                            Chief Executive Officer

 

	 	 	Address for Notice:
	 	 	 
	 	 	LifeSci Holdings LLC
	 	 	250 West 55th Street, #3401
	 	 	New York, NY 10019
	 	 	(646) 889-1200
	 	 	Attn: Andrew McDonald
	 	 	Email: andrew@lifesciacquisition.com
	 	 	 
	 	 	with a copy, which shall not constitute notice,
    to:
	 	 	 
	 	 	Loeb and Loeb LLP
	 	 	345 Park Avenue, 19th Floor
	 	 	New York, NY 10154
	 	 	Attn: Mitchell Nussbaum
	 	 	Email: mnussbaum@loeb.com

 

 

	 	NUMBER OF LOCK-UP SHARES:
	 	 
	 	1,772,034 shares of Parent Common Stock
	 	 
	 	3,146,453 Parent Warrants

 

    [Signature Page to Sponsor Lock-Up Agreement]

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