EXHIBIT 10.1

CERTAIN MATERIAL (INDICATED BY AN ASTERISK) HAS BEEN OMITTED FROM THIS DOCUMENT
PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT. THE OMITTED MATERIAL HAS BEEN
FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

FIRST AMENDMENT TO

LICENSE AGREEMENT

THIS FIRST AMENDMENT TO LICENSE AGREEMENT (the “Amendment”) is made and entered
into as of August 31, 2011 (“Amendment Effective Date”) and amends the License
Agreement effective as of January 6, 2011 (the “Agreement”) by and between
Ligand Pharmaceuticals Incorporated, a corporation organized under the laws of
Delaware (“Ligand”), and Chiva Pharmaceuticals, Inc., a corporation organized
under the laws of the Cayman Islands (“Chiva”).

WHEREAS, Ligand and Chiva have previously entered into the Agreement; and

WHEREAS, Ligand and Chiva desire to amend certain terms of the Agreement as set
forth herein.

NOW THEREFORE, in consideration of the foregoing premises and the mutual
covenants contained herein, the Parties, intending to be legally bound, agree as
follows:

 

1. Capitalized Terms. The capitalized terms used herein and not otherwise
defined shall have the same definitions as provided in the Agreement.

 

2. Amendments.

 

  (a) Equity. Section 4.2 of the Agreement is hereby deleted in its entirety and
replaced by the following:

“[Section Intentionally Omitted]”

 

  (b) Milestone Payments. Section 4.3(a) of the Agreement is hereby amended in
its entirety as follows:

“(a) In partial consideration of the rights and licenses granted by Ligand
hereunder, Chiva shall pay a one-time, non-refundable and non-creditable
milestone fee of one hundred fifty thousand US Dollars for Pradefovir
(US$150,000) and three hundred fifty thousand US Dollars ($350,000) for MB07133
to Ligand by September 1, 2011.”

 

  (c) Royalty Rates. Section 4.4(a) of the Agreement is hereby amended in its
entirety as follows:

“(a) Royalty Rates. In further consideration of the rights and licenses granted
by Ligand hereunder, Chiva shall pay to Ligand six percent (6%) of aggregate Net
Sales of Licensed Products, except for Pradefovir which shall be paid at the
percentage of nine percent (9%) of aggregate Net Sales. If a generic version of
a Licensed Product enters the market, then the royalty rate will be reduced by
[***] for that Licensed Product [***].”

 

*** Certain information on this page has been omitted and filed separately with
the Commission. Confidential treatment has been requested with respect to the
omitted portions.

1

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  (d) Representations and Covenants of Chiva. A new section 8.5 is added to the
Agreement as follows:

“8.5 Representations and Covenants of Chiva.

(a) Anti-Corruption Provisions. Chiva has not, directly or indirectly, offered,
promised, paid, authorized or given, and will not in the future, offer, promise,
pay, authorize or give, money or anything of value, directly or indirectly, to
any Government Official (as defined below) or Other Covered Party (as defined
below) for the purpose, pertaining to this Agreement, of: (i) influencing any
act or decision of the Government Official or Other Covered Party; (ii) inducing
the Government Official or Other Covered Party to do or omit to do an act in
violation of a lawful duty; (iii) securing any improper advantage; or
(iv) inducing the Government Official or Other Covered Party to influence the
act or decision of a government or government instrumentality, in order to
obtain or retain business, or direct business to, any person or entity, in any
way related to this Agreement.

For purposes of this Agreement: (i) “Government Official” means any official,
officer, employee or representative of: (A) any federal, state, provincial,
county or municipal government or any department or agency thereof; (B) any
public international organization or any department or agency thereof; or
(C) any company or other entity owned or controlled by any government; and
(ii) “Other Covered Party” means any political party or party official, or any
candidate for political office.

 

  (b) Anti-Corruption Compliance.

(i) In performing under this Agreement, Chiva and its Affiliates agree to comply
with all applicable anti-corruption laws, including, without limitation: Foreign
Corrupt Practices Act of 1977, as amended (“FCPA”); the anti-corruption laws of
China; and all laws enacted to implement the OECD Convention on Combating
Bribery of Foreign Officials in International Business Transactions.

(ii) Chiva is not aware of any Government Official or Other Covered Party having
any financial interest in the subject matter of this Agreement or in any way
personally benefiting, directly or indirectly, from this Agreement.

(iii) No political contributions or charitable donations shall be given,
offered, promised or paid at the request of any Government Official or Other
Covered Party that is in any way related to this Agreement or any related
activity, without Ligand’s prior written approval.

(iv) In the event that Chiva violates the FCPA, the anti-corruption laws of
China or any applicable anti-corruption law or breaches any provision in this
Section, Ligand shall have the right to unilaterally terminate this Agreement.”

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3. No other Amendment. Except as provided herein, the Agreement shall continue
in full force and effect.

 

4. Governing Law. This rights and obligations of the Parties under this
Amendment shall be governed, and shall be interpreted, construed, and enforced,
in all respects by the Law of the State of California, without giving effect to
any conflict of Law rule that would result in the application of the Law of any
jurisdiction other than the internal Law of the State of California to the
rights and duties of the Parties.

 

5. Counterparts. This Amendment may be executed in counterparts (including by
facsimile or electronic signature), each of which shall be deemed an original
and all of which together shall constitute one instrument.

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IN WITNESS WHEREOF, the Parties have executed this First Amendment to License
Agreement through their duly authorized representatives to be effective as of
the Amendment Effective Date.

 

LIGAND PHARMACEUTICALS INCORPORATED     CHIVA PHARMACEUTICALS, INC.   By:  

/s/ Charles Berkman

      By:  

/s/ Zhigian (David) Xi

  Title:  

Vice President, General Counsel & Secretary

      Title:  

Chief Executive Officer

  Date:  

9-1-11

      Date  

8-31-2011