Exhibit 10.2(B)
SECOND AMENDMENT TO SUBLEASE

This Second Amendment to the Sublease (this “Second Amendment”) is effective as
of this 15 day of FEBRUARY , 2017, between Seattle Biomedical Research
Institute, a Washington nonprofit corporation ("Sublandlord"), and Juno
Therapeutics, Inc., a Delaware corporation (“Subtenant”) with reference to the
following facts:

RECITALS

A.    Subtenant and Sublandlord entered into that certain Sublease between the
parties, dated November 20, 2014 (the “Sublease”), as amended by that certain
First Amendment dated February 11, 2015, for the sublease by Subtenant of
Sublease Premises located on the second floor in the building located at 307
Westlake Avenue North, Seattle, Washington.

B.    Subtenant desires to extend the Sublease for a term of three months.

NOW, THEREFORE, in consideration of the foregoing and the mutual covenant herein
contained, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

1.    Sublandlord and Subtenant agree that Sublandlord has offered, and
Subtenant has accepted, an Extension of the Sublease and that the Sublease
Extension Term shall commence June 30, 2017 and shall expire on September 30,
2017.

2.    The Monthly Rent for the Sublease Extension Term shall be as follows:
    
 
                Period
Annual Rate 
Per Square Foot
            Monthly
               Rent
 
July 1, 2017 - September 30, 2017
$45.90
$68,237.07

                   
3.    The section in paragraph 2, which states

“Subtenant may terminate this Sublease with respect to all, but not less than
all, of the Sublease Premises effective any date following March 31, 2016 by
providing one hundred and twenty (120) days prior written notice of its election
to early terminate this Sublease to the Sublandlord.”

is hereby deleted and Subtenant shall have no right to early termination of the
Sublease.

4.    On June 1, 2017, the sentence in section 3.1 of the Sublease stating

“Monthly Rent for any partial month at the beginning or the end of the

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Term shall be prorated in proportion to the number of days in such
month.”

shall be deleted and Subtenant shall not be entitled to prorations of Monthly
Rent or Additional Rent subsequent to June 1, 2017.

5.    Each party executing this Second Amendment represents and warrants that
the person signing below on its behalf is duly authorized and empowered to
execute the Second Amendment, and does so as the act and on behalf of the party
indicated below. This Second Amendment may be executed in counterparts and may
be delivered electronically.

6.    Except as modified by this Second Amendment, the terms and provisions of
the Sublease are hereby ratified and confirmed and are and shall remain in full
force and effect. Should any inconsistency arise between this Second Amendment
and the Sublease as to the specific matters that are the subject of this Second
Amendment, the terms of this Second Amendment shall control.

7.    This Second Amendment shall be binding upon and inure to the benefit of
the parties hereto, their heirs, personal representatives, successors and
assigns.

8.    Capitalized terms used herein and not otherwise defined in this Second
Amendment shall have the meanings given in the Sublease.

IN WITNESS WHEREFOR, the parties have executed this Second Amendment.

SUBLANDLORD:

Seattle Biomedical Research Institute,
a Washington nonprofit corporation

By:    /s/ Kent Irwin            
Name:    KENT IRWIN            
Title:    SENIOR DIRECTOR,    
OPERATIONS & FACILITIES

SUBTENANT:

Juno Therapeutics, Incorporated,
a Delaware corporation
By:    /s/ Andy Walker        
Name:    Andy Walker            
Title:    SVP, Technical Operations    

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STATE OF WASHINGTON    )
) ss.
COUNTY OF King     )

I certify that I know or have satisfactory evidence that Kent Irwin is the
person who appeared before me, and said person acknowledged that s/he signed
this instrument, on oath stated that s/he was authorized to execute the
instrument and acknowledged it as the Sr Director Operations & Facilities of
Seattle Biomedical Research Institute to be the free and voluntary act of such
party for the uses and purposes mentioned in the instrument.

Dated: 2/28/2017    

                     [stamp]

/s/ Katherine E. Weybright
Notary Public
Print Name Katherine E. Weybright         
My commission expires 3/26/18         

(Use this space for notarial stamp/seal

STATE OF Washington     )
) ss.
COUNTY OF King     )

I certify that I know or have satisfactory evidence that Andy Walker is the
person who appeared before me, and said person acknowledged that s/he signed
this instrument, on oath stated that s/he was authorized to execute the
instrument and acknowledged it as the SVP, Tech Ops/Manuf. of Juno Therapeutics,
Inc. to be the free and voluntary act of such party for the uses and purposes
mentioned in the instrument.

Dated: 2/15/17    

                       [seal]
/s/ Patricia Grossbard
Notary Public
Print Name Patricia Grossbard         
My commission expires 5/12/20         

(Use this space for notarial stamp/seal)

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