EXHIBIT 1
 
JOINT FILING AGREEMENT
 
The undersigned hereby agree that the Statement on this Schedule 13D, dated May 15, 2015 (the “Schedule 13D”), with respect to the ordinary shares of Adaptimmune Therapeutics plc is filed, and all amendments thereto will be filed, on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities and Exchange Act of 1934, as amended, and that this Agreement shall be included as an Exhibit to this Schedule 13D.  Each of the undersigned agrees to be responsible for the timely filing of the Schedule 13D, and for the completeness and accuracy of the information concerning itself contained therein.  This Agreement may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument.
 
IN WITNESS WHEREOF, the undersigned have executed this Agreement as of the 15th day of May, 2015.
                               
 
OrbiMed Advisors LLC
a Delaware Limited Liability Company
 
         
         
  By: /s/ Samuel D. Isaly  
    Name: Samuel D. Isaly  
    Title: Managing Member  
         
                        
 
OrbiMed Capital GP V LLC
a Delaware Limited Liability Company
 
         
  By:
OrbiMed Advisors LLC
A Delaware Limited Liability Company and its Managing Member
 
         
         
  By: /s/ Samuel D. Isaly  
    Name: Samuel D. Isaly  
    Title: Managing Member  
         
                           
                               
  Samuel D. Isaly  
         
         
  By: /s/ Samuel D. Isaly  
    Name: Samuel D. Isaly