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]


 


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