Exhibit 10.6

[***] Certain information in this document has been excluded pursuant to
Regulation S-K, Item 601(b)(10). Such excluded information is not material and
would likely cause competitive harm to the registrant if publicly disclosed.

AMENDMENT TO LICENSE, DEVELOPMENT, AND COMMERCIALIZATION AGREEMENT
This AMENDMENT TO LICENSE, DEVELOPMENT, AND COMMERCIALIZATION AGREEMENT (the
“Amendment”) is made effective June 6, 2018 (the “Amendment Effective Date”)
hereby amends the and is to the LICENSE, DEVELOPMENT, AND COMMERCIALIZATION
AGREEMENT (the “Agreement”) December 11, 2013 by and between NEOTOPE BIOSCIENCES
LIMITED (as of January 5, 2015 PROTHENA BIOSCIENCES LIMITED, “Prothena Ireland”)
with respect to all rights and obligations under this Agreement outside of the
United States, and PROTHENA BIOSCIENCES INC. (“Prothena US”) with respect to all
rights and obligations under this Agreement in the United States (Prothena US,
together with Prothena Ireland, “Prothena”), on the one hand, and F. HOFFMANN-LA
ROCHE LTD (“Roche Basel”) with respect to all rights and obligations under this
Agreement outside of the United States, and HOFFMANN-LA ROCHE INC. (“Roche
Nutley”) with respect to all rights and obligations under this Agreement in the
United States (Roche Nutley, together with Roche Basel, “Roche”), on the other
hand. All capitalized terms used herein shall have the meaning ascribed herein
or in the Agreement.
RECITALS
WHEREAS, Roche [***];
WHEREAS, [***] as of the Amendment Effective Date;
WHEREAS, Prothena and Roche want to amend the Agreement to reflect this change.
AGREEMENT
NOW, THEREFORE, in consideration of the foregoing and the covenants and promises
contained in this Amendment and intending to be legally bound, the Parties agree
as follows:
Sections 3.1 and 3.2 of the Agreement are hereby replaced as of the Amendment
Effective Date with the following new Sections 3.1 and 3.2 which read as
follows:
3.1     Antibody Products targeting Alpha-Synuclein. During the Term, except as
otherwise provided below, each Party and its Affiliates, [***], shall work
exclusively with the other Party and its Affiliates to research and develop
Antibody Products targeting Alpha-Synuclein. In particular, Prothena and its
Affiliates will not conduct, participate in, or fund,

-1-

--------------------------------------------------------------------------------

directly or indirectly, alone or with a Third Party, research, development or
commercialization activities specifically directed to any Antibody Products
targeting Alpha-Synuclein except pursuant to this Agreement, and Roche and its
Affiliates, [***], will not conduct, participate in, or fund, directly or
indirectly, alone or with a Third Party, research, development or
commercialization activities specifically directed to any Antibody Product
targeting Alpha-Synuclein except pursuant to this Agreement. [***].
3.2    [***]. [***].

-2-
[***] Certain information in this document has been excluded pursuant to
Regulation S-K, Item 601(b)(10). Such excluded information is not material and
would likely cause competitive harm to the registrant if publicly disclosed.

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the Parties have caused this Amendment to be executed
effective as of the Amendment Effective Date by their duly authorized
representatives as set forth below.

PROTHENA BIOSCIENCES LIMITED        PROTHENA BIOSCIENCES INC

By: /s/ Ashley Keating     By: /s/ Karin Walker
Name: Ashley Keating    Name: Karin Walker
Title: VP Technical Operations    Title: Chief Accounting
Officerprothenarocheamendmen_image1.gif [prothenarocheamendmen_image1.gif]
F. HOFFMANN-LA ROCHE LTD        HOFFMANN-LA ROCHE INC.

By: /s/ Stefan Arnold    By: /s/ John P. Parise    
Name: Stefan Arnold    Name: John P. Parise
Title: Head Legal Pharma    Title: Authorized Signatory

By: /s/ Tim Steven    
Name: Tim Steven
Title: Global Alliance and Asset Management Director        

3