Amendment No. 1 to the ExclusiveLicense Agreement

Exhibit 10.12B

[***] Certain information in this document has been omitted and filed separately with the Securities and Exchange Commission. Confidential treatment has been requested with respect to the omitted portions.

Amendment No. 1

to the

Exclusive License Agreement

This Amendment No. 1, dated as of August 4, 2014, is entered into between Seattle Children’s Hospital d/b/a Seattle Children’s Research Institute, a Washington non-profit corporation (“Licensor”) and Juno Therapeutics, Inc., a Delaware corporation (“Licensee”)

Accordingly, the parties agree as follows:

1. Exhibit A. Exhibit A is hereby amended to add the following patent application(s):

2. Exhibit A Restated. Exhibit A, in full, now reads as follows:

3. Full Force and Effect. Except as modified by this Amendment No. 1, all other terms of the Original Agreement will remain in full force and effect.

Seattle Children’s Hospital d/b/a Seattle Children’s Research Institute and Juno Therapeutics, Inc., Exclusive License Agreement, Amendment 1, Page 2 of 2

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