X0306 4 2017-10-02 0 0001594864 Juno Therapeutics, Inc. JUNO 0001616640 AGARWAL SUNIL C/O 400 DEXTER AVENUE NORTH SUITE 1200 SEATTLE WA 98109 0 1 0 0 President of R & D Common Stock 2017-10-02 4 S 0 7285 44.7616 D 84549 D The sales reported on this Form 4 were executed pursuant to a trading plan adopted by the reporting person on April 27, 2017 pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934. This transaction was executed in multiple trades at prices ranging from $44.50 to $45.10. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. /s/ Zachary D. Hale, attorney-in-fact 2017-10-04