Exhibit 10.1
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VIA EMAIL

March 10, 2020

Celgene Corporation
86 Morris Avenue
Summit, NJ 07901

Re:
Clarification of Rights and Obligations under the Sotatercept Agreement (as
defined below)

Dear Sir or Madam:

Reference is hereby made to that certain Amended and Restated Collaboration,
License and Option Agreement by and between Acceleron Pharma Inc. (“Acceleron”)
and Celgene Corporation (“Celgene”), dated as of September 18, 2017 (the
“Sotatercept Agreement”). Capitalized terms used herein that are not otherwise
defined have the meanings set forth in the Sotatercept Agreement.

The parties acknowledge that Acceleron is actively developing the Sotatercept
Licensed Compound in the PH Field, and the parties desire to amend certain
provisions of the Sotatercept Agreement to allow Acceleron to conduct certain
activities relating to the development of the Sotatercept Licensed Compound as
set forth below.

Accordingly, the Parties agree as follows:

1.    Celgene shall use reasonable efforts to complete the Development Safety
Update Report to the Investigational Medicinal Product Dossier required to be
submitted to relevant Health Authorities with respect to the Sotatercept
Licensed Compound as soon as practicable and, following review of such annual
report by Acceleron pursuant to Section 2.3.4 of the Sotatercept Agreement,
Celgene shall submit such annual report to the FDA. Following such submission,
Celgene shall transfer to Acceleron the responsibility for the Investigational
Medicinal Product Dossier at a mutually agreed date.

2.    Notwithstanding Section 2.3.5(a) of the Sotatercept Agreement, Acceleron
shall maintain the global safety database and clinical study database (the
“Databases”) for the Sotatercept Licensed Compound and Sotatercept Licensed
Product in the Field in the Territory, and Celgene shall provide reasonable
assistance to Acceleron in its maintenance of the Databases, at each Party’s own
expense. Celgene shall transfer to Acceleron such Databases at a mutually agreed
date.

128 Sidney Street, Cambridge, MA 02139
tel 617 649-9200
www.acceleronpharma.com

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3.    Celgene shall use reasonable efforts to complete the Investigator Brochure
update related to the Sotatercept Licensed Compound as soon as practicable and,
following completion of such update, Celgene shall transfer responsibility for
such Investigator Brochure to Acceleron as soon as practicable.

4.    As soon as practicable following the date of this letter, Celgene shall
transfer responsibility for the Material Safety Data Sheet for the Sotatercept
Licensed Compound.

5.    Celgene hereby provides notice, pursuant to Section 2.4.3 of the
Sotatercept Agreement, that: (i) Celgene has elected not to Manufacture
Sotatercept Drug Product for the Commercial Supplies of the Sotatercept Licensed
Compound and the Sotatercept Licensed Product for the Commercialization of
Sotatercept Licensed Products in the PH Field; and (ii) Acceleron is hereby
granted an exclusive license under the Celgene Technology and Celgene's interest
in the Joint Technology to Manufacture Commercial Supplies of the Sotatercept
Licensed Compound and the Sotatercept Licensed Products for the
Commercialization of Sotatercept Licensed Products in the PH Field in the
Territory.

For the avoidance of doubt, (a) the foregoing does not grant any right or
license under any Celgene Technology or Joint Technology to Acceleron to
Manufacture Sotatercept Drug Product, the Sotatercept Licensed Compound or the
Sotatercept Licensed Product for any purpose other than Commercial Supply of the
Sotatercept Licensed Compound and the Sotatercept Licensed Product for the
Commercialization of Sotatercept Licensed Product in the PH Field in the
Territory; (b) nothing in this letter agreement shall be deemed to preclude,
prevent or otherwise restrict Celgene' s right to Manufacture Sotatercept Drug
Product in the Celgene Field (for either Clinical Supply or Commercialization
purposes); (c) nothing in this letter agreement shall be deemed to designate
Acceleron as, or grant Acceleron the right to be, the “Distributing Party” for
Sotatercept Licensed Products in the PH Field, as provided in Section 2.6.2 of
the Sotatercept Agreement; and (d) nothing in this letter agreement shall be
deemed to alter the obligations of the Parties in Section 2.4.3(b) with regard
to the technology transfer or the costs associated with such transfer.

128 Sidney Street, Cambridge, MA 02139
tel 617 649-9200
www.acceleronpharma.com

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Except as expressly amended by this letter agreement, all other terms and
conditions of this Sotatercept Agreement shall remain unchanged, and the
Sotatercept Agreement shall remain in full force and effect as presently written
and the rights, duties, liabilities and obligations of Celgene and Acceleron
thereto, as currently constituted, will continue in full force and effect.

Please contact me if you have any questions.

Regards,
Acknowledged and Agreed:
 
 
/s/ Habib Dable
Celgene Corporation
 
 
Habib Dable
By: /s/ Nadim Ahmed    
President and CEO
Name: Nadim Ahmed    
 
Title: President, Hematology    
 
 
 
 
 
 

128 Sidney Street, Cambridge, MA 02139
tel 617 649-9200
www.acceleronpharma.com