Exhibit 10.17


 



 


[Date]


 


Jefferies LLC


Piper Jaffray & Co


As Representatives of the Several Underwriters


 


c/o Jefferies LLC

520 Madison Avenue

New York, New York 10022


 


c/o Piper Jaffray & Co


345 Park Avenue, 12th Floor


New York, New York 10154






	RE:	Parnell Pharmaceuticals Holdings Ltd (including any successor entity, the “Company”)


 


Ladies & Gentlemen:


 


The undersigned is a record or beneficial owner of ordinary
shares of the Company (“Ordinary Shares”) or of securities convertible into or exchangeable or exercisable
for Ordinary Shares. The Company proposes to conduct a public offering of the Ordinary Shares (the “Offering”)
for which Jefferies LLC (“Jefferies”) and Piper Jaffray & Co (“Piper Jaffray”) will act
as the representatives of the underwriters. The undersigned recognizes that the Offering will benefit each of the Company, the
selling stockholders named in the Underwriting Agreement (the “Selling Stockholders”) and the undersigned. The
undersigned acknowledges that the underwriters are relying on the representations and agreements of the undersigned contained in
this letter agreement in conducting the Offering and, at a subsequent date, in entering into an underwriting agreement (the “Underwriting
Agreement”) and other underwriting arrangements with the Company and the Selling Stockholders with respect to the Offering.


 


Annex A sets forth definitions for capitalized terms used in
this letter agreement that are not defined in the body of this agreement. Those definitions are a part of this agreement.


 


In consideration of the foregoing, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the undersigned hereby agrees that, during the Lock-up
Period, the undersigned will not (and will cause any Family Member not to), without the prior written consent of Jefferies, which
may withhold its consent in its sole discretion:


 


		·	Sell or Offer to Sell any Ordinary Shares or Related Securities currently or hereafter owned either of record or beneficially
(as defined in Rule 13d-3 under the Exchange Act) by the undersigned or such Family Member,



 


		·	enter into any Swap,



 


		·	make any demand for, or exercise any right with respect to, the registration under the Securities Act of the offer and sale
of any Ordinary Shares or Related Securities, or cause to be filed a registration statement, prospectus or prospectus supplement
(or an amendment or supplement thereto) with respect to any such registration, or



 




    	



    	 



    

  


		·	publicly announce any intention to do any of the foregoing.



 


The foregoing will not apply to the registration of the offer
and sale of the Offered Shares to the underwriters, in each case as contemplated by the Underwriting Agreement. In addition, the
foregoing restrictions shall not apply to the transfer of Ordinary Shares or Related Securities by gift or transfer without consideration,
or by operation of law or will or intestate succession (1) if the undersigned is a natural person (a) to a Family Member, (b) to
a trust whose beneficiaries either directly or indirectly consist of one or more of the undersigned’s Family Members, (c)
to a corporation, partnership, limited liability company or other entity of which the undersigned and/or the Family Members of
the undersigned are the direct or indirect legal and beneficial owners of all the outstanding equity securities or similar interests
of such corporation, partnership, limited liability company or other entity; (2) if the undersigned is a corporation, partnership,
limited liability company or other entity (a) to any trust or other entity for the direct or indirect benefit of the undersigned
or any affiliate, wholly-owned subsidiary, limited partner, member or stockholder of the undersigned, (b) to a corporation, partnership,
limited liability company or other entity of which the undersigned and any affiliate, wholly-owned subsidiary, limited partner,
member or stockholder of the undersigned are the direct or indirect legal and beneficial owners of all the outstanding equity securities
or similar interests of such corporation, partnership, limited liability company or other entity; (C) distributions of Ordinary
Shares or other share capital of the Company to shareholders of the undersigned; and (D) transfers to any investment fund or other
entity controlled or managed by the undersigned; provided, however, that in any such case, it shall be a condition to such
transfer that:


 


		·	each transferee executes and delivers to Jefferies an agreement in form and substance satisfactory to Jefferies stating that
such transferee is receiving and holding such Ordinary Shares and/or Related Securities subject to the provisions of this letter
agreement and agrees not to Sell or Offer to Sell such Ordinary Shares and/or Related Securities, engage in any Swap or engage
in any other activities restricted under this letter agreement except in accordance with this letter agreement (as if such transferee
had been an original signatory hereto), and



 


		·	prior to the expiration of the Lock-up Period, no public disclosure or filing under the Exchange Act by any party to the transfer
(donor, donee, transferor or transferee) shall be required, or made voluntarily, reporting a reduction in beneficial ownership
of Ordinary Shares or Related Securities in connection with such transfer.



 


Furthermore, notwithstanding the restrictions imposed by this
letter agreement, the undersigned may, without the prior written consent of Jefferies, establish a trading plan pursuant to Rule
10b5-1 under the Exchange Act for the transfer of Shares; provided, however, that such plan shall not provide for or permit
any transfers, sales or other dispositions of Shares during the Lock-up Period and no filing or other public announcement, whether
under the Exchange Act or otherwise, shall be required or shall be made by the undersigned or the Company in connection with such
plan during the Lock-up Period.


 


If the undersigned is an officer or director of the Company, the undersigned further agrees that the foregoing provisions shall be equally applicable to any Company-directed Ordinary Shares the undersigned may purchase or otherwise receive in the Offering (including pursuant to a directed share program).


 




    	



    	 



    

  


In addition, if the undersigned is an officer or director of
the Company, (i) Jefferies agrees that, at least three business days before the effective date of any release or waiver of the
foregoing restrictions in connection with a transfer of Ordinary Shares, Jefferies will notify the Company of the impending release
or waiver, and (ii) the Company (in accordance with the provisions of the Underwriting Agreement) will announce the impending release
or waiver by press release through a major news service at least two business days before the effective date of the release or
waiver. Any release or waiver granted by Jefferies hereunder to any such officer or director shall only be effective two business
days after the publication date of such press release. The provisions of this paragraph will not apply if both (a) the release
or waiver is effected solely to permit a transfer not for consideration and (b) the transferee has agreed in writing to be bound
by the same terms described in this letter agreement that are applicable to the transferor to the extent and for the duration that
such terms remain in effect at the time of the transfer.


 


The undersigned also agrees and consents to the entry of stop
transfer instructions with the Company’s transfer agent and registrar against the transfer of Ordinary Shares and/or Related
Securities held by the undersigned and the undersigned’s Family Members, if any, except in compliance with the foregoing
restrictions.


 


With respect to the Offering only, the undersigned waives any
registration rights relating to registration under the Securities Act of the offer and sale of any Ordinary Shares and/or any Related
Securities owned either of record or beneficially by the undersigned, including any rights to receive notice of the Offering.


 


The undersigned confirms that the undersigned has not, and has
no knowledge that any Family Member has, directly or indirectly, taken any action designed to or that might reasonably be expected
to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale of the
Ordinary Shares. The undersigned will not, and will cause any Family Member not to take, directly or indirectly, any such action.


 


Whether or not the Offering occurs as currently contemplated
or at all depends on market conditions and other factors. The Offering will only be made pursuant to the Underwriting Agreement,
the terms of which are subject to negotiation between the Company, the Selling Stockholders and the underwriters.


 


The undersigned hereby represents and warrants that the undersigned
has full power, capacity and authority to enter into this letter agreement. This letter agreement is irrevocable and will be binding
on the undersigned and the successors, heirs, personal representatives and assigns of the undersigned.


 


This letter agreement shall be governed by, and construed in
accordance with, the laws of the State of New York.


 


This letter agreement shall automatically terminate upon the
date that the Company provides written notice to Jefferies that the Company has determined not to proceed with the proposed Offering
and is terminating this letter agreement on behalf of all of the holders of Ordinary Shares subject to this letter agreement, provided
that the Company and Jefferies shall not have executed the Underwriting Agreement on or prior to such date. Assuming the Underwriting
Agreement has been executed, this letter agreement shall automatically terminate upon the date that the Underwriting Agreement
is terminated in accordance with its terms. This letter agreement shall lapse and become null and void if the closing of the Offering
has not occurred prior to  December 31, 2014. The undersigned understands that the underwriters are entering into the Underwriting
Agreement and proceeding with the Offering in reliance upon this letter agreement.


 




    	



    	 



    

  

  

  

  


	 	 
	Signature	 
	 	 
	 	 
	Printed Name of Person Signing	 
	 	 
	(Indicate capacity of person signing if signing as custodian or trustee, or on behalf of an entity)	 


 


 




    	



    	 



    

  


Certain Defined Terms

Used in Lock-up Agreement






 


For purposes of the letter agreement to which this Annex A is
attached and of which it is made a part:


 


		·	“Call Equivalent Position” shall have the meaning set forth in Rule 16a-1(b) under the Exchange Act.



 


		·	“Exchange Act” shall mean the Securities Exchange Act of 1934, as amended.



 


		·	“Family Member” shall mean the spouse of the undersigned, an immediate family member of the undersigned
or an immediate family member of the undersigned’s spouse, in each case living in the undersigned’s household or whose
principal residence is the undersigned’s household (regardless of whether such spouse or family member may at the time be
living elsewhere due to educational activities, health care treatment, military service, temporary internship or employment or
otherwise). “Immediate family member” as used above shall have the meaning set forth in Rule 16a-1(e) under
the Exchange Act.



 


		·	“Lock-up Period” shall mean the period beginning on the date hereof and continuing through the close of
trading on the date that is 180 days after the date of the Prospectus (as defined in the Underwriting Agreement).



 


		·	“Put Equivalent Position” shall have the meaning set forth in Rule 16a-1(h) under the Exchange Act.



 


		·	“Related Securities” shall mean any options or warrants or other rights to acquire Ordinary Shares or any
securities exchangeable or exercisable for or convertible into Ordinary Shares, or to acquire other securities or rights ultimately
exchangeable or exercisable for or convertible into Ordinary Shares.



 


		·	“Securities Act” shall mean the Securities Act of 1933, as amended.



 


		·	“Sell or Offer to Sell” shall mean to:



 


		-	sell, offer to sell, contract to sell or lend,



 


		-	effect any short sale or establish or increase a Put Equivalent Position or liquidate or decrease any Call Equivalent Position



 


		-	pledge, hypothecate or grant any security interest in, or



 


		-	in any other way transfer or dispose of,



 


in each case whether effected directly or
indirectly.


 


		·	“Swap” shall mean any swap, hedge or similar arrangement or agreement that transfers, in whole or in part,
the economic risk of ownership of Ordinary Shares or Related Securities, regardless of whether any such transaction is to be settled
in securities, in cash or otherwise.



 


Capitalized terms not defined in this Annex A shall have the
meanings given to them in the body of this lock-up agreement.