VIA
ELECTRONIC MAIL


 


	 	Re:	Agreement
    to Amend Conversion Price and Convert – LOC Obligation;
	 	 	Agreement
    to Amend Line of Credit Warrants


 


Dear
Investor:


 


Reference
is made to that certain October 26, 2016 Promissory Note, as amended pursuant to Amendment 1 on May 2, 2017, Amendment 2 on August
18, 2017, and Amendment 3 on January 30, 2018, in the Principal Amount of $4,000,000 (the “Promissory Note”) issued
by the Company to you and Common Stock Purchase Warrants issued in connection therewith (the “Line of Credit Warrants”
and, together with the Promissory Note, the “Line of Credit Documents”).


 


You
are being sent this letter as you are currently the holder of: (i) the Promissory Note pursuant to which you are owed principal
along with accrued interest and cash/stock fee (the “LOC Obligation”); and (ii) Line of Credit Warrants.


 


What
We Need From You


 


By
executing and delivering this letter, you hereby agree:


 


	 	I	Upon
    execution of this Letter Agreement, to automatically convert (the “Conversion”) the LOC Obligation ($4,750,000)
    into shares of Series AA Preferred at a conversion price equal to $2.50 per common share. The Series AA Preferred Certificate
    of Designation is attached hereto as Exhibit A. 
	 	 	 
	 	II	Your
    LOC Warrants will be amended via an amendment in the form attached hereto as Exhibit B (the “Amended Warrant”)
    to reflect an adjustment in exercise price from $12.00 to $3.50 per share.
	 	 	 
	 	III	You
    will receive a new warrant to purchase such number of shares of Common Stock as equal 100% of the number of shares of Common
    Stock issuable upon  conversion of the Series AA Preferred shares you receive as a result of the Conversion of your LOC
    Obligation, with a $3.50 exercise price, in the form  attached hereto as Exhibit C. 





 


Upon
the triggering of Conversion, the Company shall, within ten (10) business days, send you: (i) written notice specifying the number
of shares of Series AA Preferred Stock to be issued to you, and the number of Warrants to be issued to you; (ii) a stock certificate
for the Series AA Preferred Stock shares; (iii) the Amended Warrant; and (iv) the Warrants. 


 


 


 







    	 



    	 



    




 


By
your agreement and acknowledgment below, this Letter Agreement shall serve as written confirmation that:


 


	 	1.	You
    agree to the terms of the Conversion, the Amended Warrants, and the Warrants.
	 	 	 
	 	2.	Upon
    the date of the Conversion, the Amended Warrants shall be deemed issued as described herein irrespective of your physical
    receipt of same. 
	 	 	 
	 	3.	Upon
    the date of the Conversion, the Warrants shall be deemed issued as described herein irrespective of your physical receipt
    of same. 
	 	 	 
	 	4.	You
    acknowledge and agree that upon the execution of this Letter Agreement, the October 26, 2016 Promissory Note (including Amendments
     1, 2, and 3) and the LOC Obligation shall be cancelled and no longer in full force or effect. 


 


As
further consideration for this agreement, without your prior written consent, the Company shall not grant or permit to exist any
security interest, lien, charge or other encumbrance on its assets or the assets of any subsidiary, other than the granting of
a security interest on accounts receivable granted in connection with an account receivable financing transaction. The foregoing
restriction shall expire and be of no further force or effect at such time at the Company’s common stock is traded on a
National Securities Exchange.


 


By
signing below, this Letter Agreement shall serve as written confirmation that you have reviewed this Letter Agreement (and consulted
with your legal and tax advisors to the extent you deemed necessary) and agree to the terms and conditions of the Conversion,
the Amended Warrants, and the Warrants as described herein. By signing below, you understand that you will be releasing and discharging
the Company and its affiliates from any and all obligations and duties that such persons may have to you with respect to the LOC
Obligation.


 


This
Letter Agreement contains the entire understanding between and among the parties and supersedes any prior understandings and agreements
among them respecting the subject matter of this Letter Agreement. In addition, you hereby represent that you meet the requirements
of at least one of the suitability standards for an “accredited investor” as that term is defined in Regulation D
promulgated under the Securities Act of 1933, as amended and that you have had the opportunity to obtain any additional information,
to the extent the Company has such information in its possession or could acquire it without unreasonable effort or expense, necessary
in connection with the matters set forth in this Letter Agreement including, without limitation, information concerning the financial
condition, results of operations, capitalization and business of the Company deemed relevant by you or your advisors, if any,
and all such requested information, to the extent the Company had such information in its possession or could acquire it without
unreasonable effort or expense, has been provided to your full satisfaction. This Letter Agreement shall be governed by and construed
in accordance with the laws of the Commonwealth of Massachusetts without regard to the choice of law principles. This Letter Agreement
may be executed in any number of counterparts, each of which shall be an original but all of which together shall constitute one
and the same instrument. In case any provision of this Letter Agreement shall be held to be invalid, illegal or unenforceable,
such provision shall be severable from the rest of this Letter Agreement, and the validity legality and enforceability of the
remaining provisions shall not in any way be affected or impaired thereby.


 








This
letter evidences waiver by the undersigned with respect to any and all defaults or events of default by the Company with respect
to any failure by the Company to comply with any covenants contained in the Line of Credit Documents.


 


The
parties hereby consent and agree that if this Letter Agreement shall at any time be deemed by the parties for any reason insufficient,
in whole or in part, to carry out the true intent and spirit hereof or thereof, the parties will execute or cause to be executed
such other and further assurances and documents as in the reasonable opinion of the parties may be reasonably required in order
more effectively to accomplish the purposes of this Letter Agreement.


 


***REMAINDER
OF PAGE INTENTIONALLY LEFT BLANK***


 


 


 




    	 



    	 



    

 


Please
indicate confirmation of the terms provided herein by executing and returning this letter in the space provided below.


 


	 	Very
    truly yours,
	 	 
	 	PRESSURE
    BIOSCIENCES, INC.
	 	 	 
	 	By:	 
	 	Name:	Richard
    T. Schumacher
	 	Title:	Chief
    Executive Officer
	 	 	 
	 	Date:
    ____________, 2018


 


	ACCEPTED
    AND AGREED:	 
	 	 
	 	 
	Date:
    ____________, 2018