EX-10.4



 Exhibit 10.4 

MABVAX THERAPEUTICS, INC. 

February 12, 2014 
 MabVax Therapeutics,
Inc. 
 11588 Sorrento Valley Road, Suite 20 
 Sand Diego,
California 92121 
 Re: MabVax Therapeutics, Inc. – Lock-Up Agreement 

Dear Sirs: 
 This Lock-Up Agreement is being
delivered to you in connection with the Securities Purchase Agreement (the “Purchase Agreement”), dated as of February 12, 2014 by and among MabVax Therapeutics, Inc. (the “Company”) and the investors party
thereto (the “Buyers”), with respect to the issuance of (i) shares of Series C-1 Preferred Stock which are convertible into shares of common stock of common stock of the Company, par value $0.001 per share (the “Common
Stock”), (ii) Series C-1 Warrants which will be exercisable to purchase Series C-1 Preferred Stock and (iii) Initial Warrants which will be exercisable to purchase Common Stock. Capitalized terms used herein and not otherwise
defined herein shall have the respective meanings set forth in the Purchase Agreement. 
 In order to induce the Buyers to enter into the
Purchase Agreement, the undersigned agrees that, commencing on the date hereof and ending on the one (1) year anniversary of the Public Company Date (the “Lock-Up Period”), the undersigned will not, and will cause all
Affiliates of the undersigned or any person in privity with the undersigned or any Affiliate of the undersigned not to, (i) sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option to purchase, make any short sale
or otherwise dispose of or agree to dispose of, directly or indirectly, any shares of Common Stock or Common Stock Equivalents, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning
of Section 16 of the Securities and Exchange Act of 1934, as amended and the rules and regulations of the Securities and Exchange Commission promulgated thereunder with respect to any shares of Common Stock or Common Stock Equivalents owned
directly by the undersigned (including holding as a custodian) or with respect to which the undersigned has beneficial ownership within the rules and regulations of the Securities and Exchange Commission (collectively, the
“Undersigned’s Shares”), or (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any of the Undersigned’s Shares, whether any
such transaction described in clause (i) or (ii) above is to be settled by delivery of shares of Common Stock or other securities, in cash or otherwise, (3) make any demand for or exercise any right or cause to be filed a registration
statement, including any amendments thereto, with respect to the registration of any shares of Common Stock or Common Stock Equivalents or (4) publicly disclose the intention to do any of the foregoing. 

The foregoing restriction is expressly agreed to preclude the undersigned, and any Affiliate of the undersigned and any person in privity with
the undersigned or any Affiliate of the undersigned, from engaging in any hedging or other transaction which is designed to or which reasonably could be expected to lead to or result in a sale or disposition of the Undersigned’s Shares even if
the Undersigned’s Shares would be disposed of by someone other than the undersigned. Such prohibited hedging or other transactions would include, without limitation, any short sale or any purchase, sale or grant of any right (including, without
limitation, any put or call option) with respect to any of the Undersigned’s Shares or with respect to any security that includes, relates to, or derives any significant part of its value from the Undersigned’s Shares. 

Notwithstanding the foregoing, the undersigned may transfer the Undersigned’s Shares (i) as a bona fide gift or gifts,
provided that the donee or donees thereof agree to be bound in writing by the restrictions set forth herein, or (ii) to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, provided that
the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided further that any such transfer shall not involve a disposition for value. For purposes of this Lock-Up Agreement, “immediate family”
shall mean any relationship by blood, marriage or adoption, not more remote than first cousin. The 

  
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undersigned now has, and, except as contemplated by the immediately preceding sentence, for the duration of this Lock-Up Agreement will have, good and marketable title to the Undersigned’s
Shares, free and clear of all liens, encumbrances, and claims whatsoever. The undersigned also agrees and consents to the entry of stop transfer instructions with the Company’s transfer agent (the “Transfer Agent”) and
registrar against the transfer of the Undersigned’s Shares except in compliance with the foregoing restrictions. 
 In order to enforce
this covenant, the Company shall impose irrevocable stop-transfer instructions preventing the Transfer Agent from effecting any actions in violation of this Lock-Up Agreement. 

The undersigned acknowledges that the execution, delivery and performance of this Lock-Up Agreement is a material inducement to each Buyer to
complete the transactions contemplated by the Purchase Agreement and that the Company shall be entitled to specific performance of the undersigned’s obligations hereunder. The undersigned hereby represents that the undersigned has the power and
authority to execute, deliver and perform this Lock-Up Agreement, that the undersigned has received adequate consideration therefor and that the undersigned will indirectly benefit from the closing of the transactions contemplated by the Purchase
Agreement. 
 The undersigned understands and agrees that this Lock-Up Agreement is irrevocable and shall be binding upon the
undersigned’s heirs, legal representatives, successors, and assigns. 
 This Lock-Up Agreement may be executed in two counterparts,
each of which shall be deemed an original but both of which shall be considered one and the same instrument. 
 This Lock-Up Agreement
constitutes the entire agreement and understanding of the parties hereto with respect to the subject matter hereof and supersedes all prior agreements and understandings relating to such subject matter, including, without limitation, that certain
Amended and Restated Investors’ Rights Agreement, dated as of November 2, 2012, by and among the Company and the other parties thereto. 

This Lock-Up Agreement will be governed by and construed in accordance with the laws of the State of New York, without giving effect to any
choice of law or conflicting provision or rule (whether of the State of New York, or any other jurisdiction) that would cause the laws of any jurisdiction other than the State of New York to be applied. In furtherance of the foregoing, the internal
laws of the State of New York will control the interpretation and construction of this Lock-Up Agreement, even if under such jurisdiction’s choice of law or conflict of law analysis, the substantive law of some other jurisdiction would
ordinarily apply. 
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	Very truly yours,
	
	RTP VENTURE FUND, LLC
		
	By:	 	 /s/ Philip O. Livingston

	Name:	 	 Philip O. Livingston, M.D.

	Title:	 	 Manager

	
	Very truly yours,
	
	JOAN L. TWEEDY 2011 REVOCABLE TRUST
		
	By:	 	 /s/ Philip O. Livingston

	Name:	 	 Philip O. Livingston, M.D.

	Title:	 	 Trustee




 

			
	Very truly yours,
	
	 /s/ Philip O. Livingston

	Philip O. Livingston, M.D.


  

			
	Agreed to and Acknowledged:
	
	MABVAX THERAPEUTICS, INC.
		
	By:	 	 /s/ J. David Hansen

		 	J. David Hansen, President and
		 	Chief Executive Officer


  
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