CONSENT TO SUBLEASE AGREEMENT
THIS CONSENT TO SUBLEASE AGREEMENT (this "Agreement") is made as of March 28,
2016, by and among HCP BTC, LLC, a Delaware limited liability company
("Landlord"), AMGEN INC., a Delaware corporation ("Tenant"), and PROTHENA
BIOSCIENCES INC, a Delaware corporation ("Subtenant").
R E C I T A L S
A.Reference is hereby made to that certain Build-to-Suit Lease dated December
20, 2001, between Landlord, formerly known as Slough BTC, LLC, and Tenant, as
successor in interest to Tularik Inc. (the "Original Lease"), as amended by that
certain First Amendment to Build-to-Suit Lease dated January 22, 2003 (the
"First Amendment"), that certain Second Amendment to Build-to-Suit Lease dated
March 26, 2004 (the "Second Amendment"), that certain Third Amendment to
Build-to-Suit Lease dated August 12, 2004 (the "Third Amendment"), that certain
Fourth Amendment to Build-to-Suit Lease and First Amendment to Workletter dated
June 19, 2006 (the "Fourth Amendment"), that certain Fifth Amendment to
Build-to-Suit Lease and Second Amendment to Workletter dated June 19, 2006 (the
"Fifth Amendment"), that certain Sixth Amendment to Build-to-Suit Lease and
Third Amendment to Workletter dated November 21, 2006 (the "Sixth Amendment"),
and that certain Seventh Amendment to Build-to-Suit Lease and Fourth Amendment
to Workletter dated February 21, 2008 (the "Seventh Amendment", and together
with the Original Lease, the First Amendment, Second Amendment, Third Amendment,
Fourth Amendment, Fifth Amendment and Sixth Amendment, collectively, the
"Lease"), for seven (7) buildings in the Oyster Point center located in South
San Francisco, California (the "Premises"), including the building located at
331 Oyster Point Boulevard, consisting of 128,751 rentable square feet (the
"Building").
B.Pursuant to the terms of Article 15 of the Original Lease, Tenant has
requested Landlord's consent to that certain Sublease dated March 22, 2016,
between Tenant and Subtenant (the "Sublease"), with respect to a subletting by
Subtenant of the entire Building, as more particularly described in the Sublease
(the "Sublet Premises"). A copy of the Sublease is attached hereto as Exhibit A.
Landlord is willing to consent to the Sublease on the terms and conditions
contained herein.
C.All defined terms not otherwise expressly defined herein shall have the
respective meanings given in the Lease.
A G R E E M E N T
1.Landlord's Consent. Landlord hereby consents to the Sublease; provided,
however, notwithstanding anything contained in the Sublease to the contrary,
such consent is granted by Landlord only upon the terms and conditions set forth
in this Agreement. The Sublease is subject and subordinate to the Lease.
Landlord shall not be bound by any of the terms, covenants, conditions,
provisions or agreements of the Sublease. Subtenant acknowledges for the benefit
of Landlord that Landlord has made no representation or warranty to Subtenant as
to the compliance of the Sublet Premises with any law, statute, ordinance, rule
or regulation nor is Landlord obligated to provide, or pay for, any work or
improvements relating to Subtenant's occupancy of the Sublet Premises except

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as specifically set forth in the Lease (as between Landlord and Tenant) or in
the Subtenant Workletter (the "Workletter"), attached hereto as Exhibit B;
provided that (i) the foregoing shall not modify Landlord's ongoing repair and
maintenance obligations set forth in the Lease; (ii) Tenant and Subtenant
acknowledge and agree that, as set forth in the Lease, including Section 13.4 of
the Original Lease, as between Landlord and Tenant, Tenant shall be responsible
to make all alterations or additions to the Property required by any and all
Requirements (as defined in the Lease) because of Tenant's (including
Subtenant's) construction of improvements (provided, that, nothing herein is
waiving any rights Tenant may have with respect to latent defects, as referenced
in Section 5.2 of the Original Lease); and (iii) Subtenant and Tenant
acknowledge and agree that, as between Tenant and Subtenant, nothing herein
shall modify or change the allocation of responsibility and costs set forth in
the Sublease with respect to any such alterations or additions to the Property
required by applicable Requirements. Tenant and Subtenant hereby represent and
warrant to Landlord that the copy of the Sublease attached hereto is a full,
complete and accurate copy of the Sublease, and that there are no other
documents or instruments relating to the use of the Sublet Premises by Subtenant
other than the Sublease. To the extent any terms or provisions of the Lease or
the Sublease are inconsistent with the terms of this Agreement, the terms of
this Agreement control.
2.Reimbursement of Landlord. Within thirty (30) days after invoice, Tenant shall
reimburse Landlord all of Landlord's reasonable costs and expenses incurred in
connection with its review and consent of the Sublease and preparation and
negotiation of this Agreement.
3.Non-Release of Tenant; Further Transfers. Neither the Sublease nor this
consent thereto shall release or discharge Tenant from any liability, whether
past, present or future, under the Lease or alter the primary liability of the
Tenant to pay the rent and perform and comply with all of the obligations of
Tenant to be performed under the Lease (including the payment of all bills
rendered by Landlord for charges incurred by Subtenant for services and
materials supplied to the Sublet Premises during the Term of the Sublease).
Neither the Sublease nor this consent thereto shall be construed as a waiver of
Landlord's right to consent to any further subletting either by Tenant or by
Subtenant, or to any assignment by Tenant of the Lease or assignment by
Subtenant of the Sublease, or as a consent to any portion of the Sublet Premises
being used or occupied by any other party. Without limiting the generality of
the foregoing, nothing herein shall modify or amend Landlord's or Tenant's
respective rights and obligations under the Lease with respect to any future
assignments or subleases. Notwithstanding the preceding portion of this Section
3 or any provision to the contrary set forth in the Lease or the Sublease,
Landlord's consent shall not be required in connection with any assignment or
subleasing of Subtenant's interest in the Sublease that would constitute a
"Permitted Transfer" pursuant to the terms of Section 15.1 of the Original
Lease, if all references in Section 15.1 were deemed to refer to "Subtenant"
instead of "Tenant" and to the "Sublease" instead of the "Lease". The foregoing
shall not release Subtenant of any of Subtenant's obligations with respect to
any transfer as set forth in Section 9.16 of the Sublease.
4.Relationship With Landlord. Tenant hereby assigns and transfers to Landlord
Tenant's interest in the Sublease and all rentals and income arising therefrom,
subject to the terms of this Section 4. Landlord, by consenting to the Sublease
agrees that until an event of default beyond all applicable notice and cure
periods shall occur in the performance of Tenant's obligations under the Lease,
Tenant may receive, collect and enjoy the full benefits of such interest in the
Sublease, including, without limitation, the rents and income arising therefrom.
In the event Tenant shall be in default in the performance of its obligations to
Landlord under Section 18.1 of the Original Lease (as amended)

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beyond all applicable notice and cure periods, Landlord may, at its option by
notice to Tenant, elect to receive and collect, directly from Subtenant, all
rent and any other sums owing and to be owed under the Sublease, as further set
forth in Section 4.1, below. In the event that the Lease shall be terminated,
Landlord may, at its option by notice to Tenant, either (i) terminate the
Sublease, or (ii) elect to succeed to Tenant's interest in the Sublease and
cause Subtenant to attorn to Landlord, as further set forth in Section 4.2,
below.
4.1    Landlord's Election to Receive Rents. Landlord shall not, by reason of
the Sublease, or by reason of the collection of rents or any other sums from
Subtenant pursuant to Section 4 above, be deemed liable to Subtenant for any
failure of Tenant to perform and comply with any obligation of Tenant, and
Tenant hereby irrevocably authorizes and directs Subtenant, upon receipt of any
written notice from Landlord stating that an event of default exists in the
performance of Tenant's obligations under the Lease beyond all applicable notice
and cure periods, to pay to Landlord the rents and any other sums due and to
become due under the Sublease. Tenant agrees that Subtenant shall have the right
to rely upon any such statement and request from Landlord, and that Subtenant
shall pay any such rents and any other sums to Landlord without any obligation
or right to inquire as to whether such default exists and notwithstanding any
notice from or claim from Tenant to the contrary. Tenant shall not have, and
hereby waives, any right or claim against Subtenant for any such rents or any
other sums so paid by Subtenant to Landlord. Landlord shall credit Tenant with
any rent or other sums received by Landlord under such assignment but the
acceptance of any payment on account of rent from Subtenant as the result of any
such default shall in no manner whatsoever be deemed an attornment by the
Landlord to Subtenant or by Subtenant to Landlord, be deemed a waiver by
Landlord of any provision of the Lease, or serve to release Tenant from any
liability under the terms, covenants, conditions, provisions or agreements under
the Lease. Notwithstanding the foregoing, any other payment of rent from
Subtenant directly to Landlord, regardless of the circumstances or reasons
therefor, shall in no manner whatsoever be deemed an attornment by Subtenant to
Landlord in the absence of a specific written agreement signed by Landlord to
such an effect.
4.2    Landlord's Election of Tenant's Attornment. In the event Landlord elects,
at its option, to cause Subtenant to attorn to Landlord pursuant to Section 4
above, Landlord shall undertake the obligations of Tenant under the Sublease
from the time of the termination by Landlord of the Lease, but Landlord shall
not (i) be liable for any prepayment of more than one month's rent or any
security deposit paid by Subtenant unless such prepayment or security deposit
has been actually received by Landlord, (ii) be liable for any previous act or
omission of Tenant under the Lease or for any other defaults of Tenant under the
Sublease, except for any default of a continuing nature that continues after the
date Landlord undertakes the obligations of Tenant under the Sublease, (iii) be
subject to any defenses or offsets previously accrued which Subtenant may have
against Tenant, or (iv) be bound by any changes or modifications made to the
Sublease without the written consent of Landlord, which consent shall not be
unreasonably withheld, conditioned, or delayed.
4.3    Operational Matters. Notwithstanding Landlord's consent to the Sublease
as set forth herein, Landlord shall not be obligated to accept from Subtenant
any payments of the Minimum Rental, additional rent, and Tenant's Operating Cost
Share due under the Lease, all of which shall be paid by Tenant as set forth in
the Lease. Requests for services as provided under the Lease, including without
limitation, repair and maintenance services of the Common Areas of the Center
and structural portions of the roofs and Buildings, parking services, or any
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to be performed by Landlord under the terms of the Lease, may be made directly
by Subtenant to Landlord with a copy of such request to be provided to Tenant.
So long as a copy of any such request is also provided to Tenant, Landlord
hereby agrees to respond to any such direct request of Subtenant. The right of
Subtenant to request services directly from Landlord is granted for convenience
only.
4.4    No Waiver. The acceptance of any amounts by Landlord from Subtenant or
any other party shall not be deemed a waiver by Landlord of the obligation of
Tenant to pay any or all amount due and owing under the Lease. Landlord shall
credit Tenant with such amounts received by Landlord, but the acceptance of any
payment from Subtenant or any other party shall in no manner whatsoever be
deemed an attornment by Landlord to Subtenant or by Subtenant to Landlord, be
deemed a waiver by Landlord of any provision of the Lease, or serve to release
Tenant from any liability under the terms, covenants, conditions, provisions or
agreements under the Lease. The performance of any obligation required by Tenant
under the Lease by Subtenant or any other party shall not be deemed a waiver by
Landlord of the duty of Tenant to perform any other obligation as to which
performance is or becomes due under the Lease.
4.5    Acts of Subtenant. Any act or omission by Subtenant, or by any other
person or entity for whose acts or omissions Tenant is liable or responsible
under the terms of the Lease, that violates any of the provisions of the Lease,
shall be deemed a violation of the Lease by Tenant, subject to any applicable
notice and cure provisions contained in the Lease.
4.6    Indemnification. Subtenant shall indemnify, defend and hold Landlord and
its members, partners, shareholders, officers, directors, agents, employees and
contractors harmless from any and all liability for bodily injury to or death of
any person, or loss of or damage to the property of any person, and all actions,
claims, demands, costs (including, but not limited to, reasonable attorneys'
fees), damages or expenses of any kind arising therefrom which may be brought or
made against Landlord or which Landlord may pay or incur by reason of the use,
occupancy and enjoyment of the Sublet Premises by Subtenant or any invitees,
sublessees, licensees, assignees, agents, employees or contractors of Subtenant
or holding under Subtenant (including, but not limited to, any such matters
arising out of or in connection with any early entry upon the Sublet Premises by
Subtenant pursuant to the terms of the Sublease) from any cause whatsoever other
than negligence or willful misconduct or omission by Landlord or its agents,
employees or contractors. Landlord and its members, partners, shareholders,
officers, directors, agents, employees and contractors shall not be liable for,
and Subtenant hereby waives all claims against such persons for, damages to
goods, wares and merchandise in or upon the Sublet Premises, or for injuries to
Subtenant, its agents or third persons in or upon the Sublet Premises, from any
cause whatsoever other than negligence or willful misconduct or omission by
Landlord or its agents, employees or contractors. Subtenant shall give prompt
notice to Landlord of any casualty or accident in, on or about the Sublet
Premises. Tenant confirms that Subtenant's indemnity above is in addition to
(and does not replace, modify, or negate) Tenant's indemnification obligations
under the Lease, including, without limitation, Tenant's indemnification of
Landlord set forth in Section 14.6(a) of the Original Lease. The provisions of
this Section 4.6 shall survive the expiration or sooner termination of the
Sublease with respect to any claims or liability arising in connection with any
event occurring prior to such expiration or termination.
4.7    Insurance. Prior to Subtenant's occupancy of the Sublet Premises,
Subtenant shall provide Landlord with certificates of all of the insurance
required to be carried by Subtenant by the terms of the Sublease, which shall
show Landlord as being an additional insured thereunder. The

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waiver of subrogation contained in Section 14.4 of the Lease shall apply as
between Landlord and Subtenant.
4.8    No Consent to Alterations or Particular Use. Notwithstanding anything
contained in the Sublease to the contrary, Landlord's consent to the Sublease as
contained in this Agreement shall not be deemed to be a consent to (i) any
alteration or work of improvement that Tenant or Subtenant may desire or intend
in the Sublet Premises, except as set forth in the Workletter and this Section
4.8, (ii) any use of hazardous, radioactive or toxic materials in or about the
Sublet Premises, except as expressly permitted in the Lease, including without
limitation pursuant to Sections 13.1 and 13.6 of the Lease, or (iii) any signage
proposed to be installed for the benefit of Subtenant, except as set forth in
Section 4.10 below. Notwithstanding the foregoing, Subtenant shall not be
required to obtain Landlord's consent for interior alterations costing less than
One Hundred Thousand Dollars ($100,000.00) for any single project (i.e., any
single item of alterations or set of related alterations in the Sublet
Premises). Regardless of whether Landlord's consent would otherwise be required
under the Sublease or this Agreement, Subtenant shall provide Landlord with
prior written notice of any proposed alterations, additions or improvements
having a cumulative estimated cost of more than Four Hundred Thousand Dollars
($400,000.00) in any twelve (12) month period. Notwithstanding any other
provisions of this Section 4.8, under no circumstances shall Subtenant make any
structural alterations or improvements, or any substantial changes to the roof
or substantial equipment installations on the roof, or any substantial changes
or alterations to building systems, without Landlord's prior written consent.
4.9    Existing Improvements. Notwithstanding anything to the contrary set forth
in the Lease, Landlord confirms and agrees that Landlord shall not require the
removal or restoration of any of the Tenant Improvements (as defined in the
Lease) or any other alterations, additions, or improvements existing in the
Sublet Premises as of the date hereof. Upon expiration or earlier termination of
the Lease, all such existing improvements (including the Tenant Improvements),
alterations and additions shall be surrendered to Landlord in the condition
required for such surrender set forth in the Lease.
4.10    Signage. Pursuant to Section 11.5 of the Original Lease (x) Tenant has
the right to display its corporate name, logo and/or insignia with lighted
signage on the exterior of the Building and in front of the entrance to the
Building, subject to (a) Landlord's prior approval as to location, size, design
and composition (which approval shall not be unreasonably withheld, conditioned
or delayed), (b) the sign criteria established for the Center (as defined in the
Lease) from time to time and (c) all restrictions and requirements of applicable
law and of any covenants, conditions and restrictions or other written
agreements now or hereafter applicable to the Property, and (y) in the event
Landlord installs at the Project (as defined in the Lease) any monument sign(s)
on which identification signage for any individual tenants is included, Tenant
shall be entitled to have identification signage on such monument sign(s) on a
basis comparable to that made available to any other tenants ("Tenant's Signage
Rights"). Pursuant to the Sublease, Tenant grants to Subtenant signage rights
("Subtenant's Signage Rights") that are substantially the same as Tenant's
Signage Rights applicable to the Sublet Premises. Landlord agrees that Subtenant
may exercise Subtenant's Signage Rights to the same extent as Tenant is
permitted to exercise Tenant's Signage Rights applicable to the Sublet Premises
so that during the Sublease Term, Tenant's Signage Rights shall apply to
Subtenant as if the word "Subtenant" replaced the references to Tenant in
Section 11.5 of the Original

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Lease. Subtenant shall immediately repair any damage caused by installation and
removal of signs under this Section 4.10 from time to time.
5.General Provisions.
5.1    Consideration for Sublease. Tenant and Subtenant represent and warrant
that there are no additional payments of rent or any other consideration of any
type payable by Subtenant to Tenant with regard to the Sublet Premises other
than as disclosed in the Sublease. Landlord acknowledges that the consideration
payable by Subtenant under the Sublease is less than the amount payable by
Tenant for the Sublet Premises under the Lease and, accordingly, no transfer
premium is payable in connection with the Sublease.
5.2    Brokerage Commission. Tenant and Subtenant covenant and agree that under
no circumstances shall Landlord be liable for any brokerage commission or other
charge or expense in connection with the Sublease and Tenant and Subtenant agree
to protect, defend indemnify and hold Landlord harmless from and against the
same and from any cost or expense (including, but not limited to, reasonable
attorney's fees) incurred by Landlord in resisting any claim for any such
brokerage commission.
5.3    Controlling Law. The terms and provisions of this Agreement shall be
construed in accordance with and governed by the laws of the State of
California.
5.4    Binding Effect. This Agreement shall be binding upon and inure to the
benefit of the parties hereto, their heirs, successors and permitted assigns. As
used herein, the singular number includes the plural and the masculine gender
includes the feminine and neuter.
5.5    Captions. The paragraph captions utilized herein are in no way intended
to interpret or limit the terms and conditions hereof; rather, they are intended
for purposes of convenience only.
5.6    Partial Invalidity. If any term, provision or condition contained in this
Agreement shall, to any extent, be invalid or unenforceable, the remainder of
this Agreement, or the application of such term, provision or condition to
persons or circumstances other than those with respect to which it is invalid or
unenforceable, shall not be affected thereby, and each and every other term,
provision and condition of this Agreement shall be valid and enforceable to the
fullest extent permitted by law.
5.7    Attorneys' Fees. If any party or parties commence litigation against any
other party or parties for the specific performance of this Agreement, for
damages for the breach hereof or otherwise for enforcement of any remedy
hereunder, the parties hereto agree to and hereby do waive any right to a trial
by jury and, in the event of any such commencement of litigation, the prevailing
party or parties shall be entitled to recover from the other party or parties
such costs and reasonable attorneys' fees as may have been incurred.
5.8    Notices. All notices, consents, waivers and other communications shall be
delivered in accordance with Article 21 of the Original Lease to the parties at
their respective addresses as set forth below (or such other notice addresses
provided by any party to the other parties in accordance with the terms hereof.
Further, in addition to the notice methods set forth in the Lease,

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the parties may send notice by electronic mail with a hard copy to follow by one
of the methods set forth in the Lease. Any notice sent by email shall be deemed
delivered on the date that such email was sent, unless there is an automatic
reply indicating that the recipient is out of the office or that the email was
not delivered (in which event, delivery shall be determined based on delivery of
the hard copy pursuant to one of the methods set forth in the Lease).
To Landlord:
HCP, Inc.
1920 Main Street, Suite 1200
Irvine, CA 92614
Attention: Legal Department

Email: aplayle@hcpi.com
with a copy to
HCP Life Science Estates
950 Tower Lane, Suite 1650
Foster City, CA 94404
Attention: Jonathan M. Bergschneider
Email: jbergschneider@hcpi.com
and
Allen Matkins Leck Gamble Mallory & Natsis LLP
1901 Avenue of the Stars, Suite 1800
Los Angeles, California 90067
Attention: Anton N. Natsis, Esq.
Email: tnatsis@allenmatkins.com

To Tenant:
Amgen Inc.

One Amgen Center Drive
Mail Stop: 28-1-A
Thousand Oaks, CA 91320-1799
Attention: Corporate Real Estate
Email: chbarry@amgen.com; and
    jthaker@amgen.com

with a copy to

Amgen Inc.
One Amgen Center Drive
Mail Stop: 35-2-A
Thousand Oaks, CA 91320-1799
Attention: Operations Law Group
Email: gmintz@amgen.com

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To Subtenant:
Prothena Biosciences Inc.
650 Gateway Boulevard
South San Francisco, CA 94080
Attention: Chief Financial Officer
Email: tran.nguyen@prothena.com

with a copy to:

Prothena Biosciences Inc.
650 Gateway Boulevard
South San Francisco, CA 94080
Attention: Chief Legal Officer
Email: bill.homan@prothena.com

5.9    SEC Filings. In the event either Tenant or Subtenant or any of its
affiliates (such party, a "Filing Party") is required to file with the
Securities and Exchange Commission or the securities regulators of any state or
other jurisdiction a registration statement or any other disclosure document
which describes or refers to the Sublease, this Agreement, or the Workletter
under the Securities Act of 1933, as amended, the Securities Exchange Act, of
1934, as amended, any other applicable securities law or the rules of any
national securities exchange, the Filing Party shall be entitled to file an
unredacted copy of the Original Lease, the Sublease, this Agreement, and the
Workletter, and a copy of the Fifth Amendment with those redactions of the Fifth
Amendment reflected in the version attached to Exhibit A of the Sublease.

[Remainder of page left intentionally blank; signature pages follow.]

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IN WITNESS WHEREOF, the parties have executed this Consent to Sublease Agreement
as of the day and year first above written.
"Landlord"
HCP BTC, LLC,
a Delaware limited liability company
By: HCP Estates USA Inc.,
a Delaware corporation
By: /s/ Jonathan M. Bergschneider 
Jonathan M. Bergschneider
Executive Vice President

"Tenant"

AMGEN INC.,
a Delaware corporation

By: /s/ David Meline
Name: David Meline

Title: Executive Vice President and
Chief Financial Officer

"Subtenant"

PROTHENA BIOSCIENCES INC,
a Delaware corporation

By: /s/ Tran Nguyen
Name: Tran Nguyen
Title: CFO
By: /s/ A. W. Homan
Name: A. W. Homan
Title: CLO & Secretary
    

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EXHIBIT A
THE SUBLEASE
[See attached.]

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EXHIBIT B
SUBTENANT WORKLETTER

[To be inserted]

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WORKLETTER
This Workletter ("Workletter") is attached to and made part of that certain
Consent to Sublease Agreement dated March 28, 2016 (the "Consent"), by and among
HCP BTC, LLC, a Delaware limited liability company ("Landlord"), Amgen Inc., a
Delaware corporation ("Tenant") and Prothena Biosciences Inc, a Delaware
corporation ("Subtenant"), with reference to that certain Build-to-Suit Lease
dated as of December 20, 2001 (the "Original Lease" and, as amended to date, the
"Lease"), by and between Landlord (formerly known as Slough BTC, LLC) and Tenant
(as successor in interest to Tularik Inc.) and that certain Sublease dated March
22, 2016 (the "Sublease"), by and between Tenant and Subtenant. The terms of
this Workletter are incorporated in the Consent for all purposes. In the event
of any conflict between the terms of the Lease (including Exhibit C attached to
the Original Lease) or the Consent and this Workletter, this Workletter shall
control (i) with respect to the Lease, for purposes of the Subtenant
Improvements and Subtenant's Work (as such terms are defined below) only, and
(ii) with respect to the Consent, for all purposes.
1.Defined Terms. As used in this Workletter, the following capitalized terms
have the following meanings:
(a)    Architect. Any architect selected by Subtenant with the written approval
of Landlord and Tenant (which shall not be unreasonably withheld, conditioned or
delayed) with respect to the Subtenant Improvements which Subtenant is to design
pursuant to this Workletter. Landlord and Tenant hereby agree that DG
Architects, Inc dba DGA is an architect reasonably acceptable to Landlord and
Tenant and shall be deemed an approved architect pursuant to this Paragraph
1(a).
(b)    Building. The building located at 331 Oyster Point Boulevard, South San
Francisco, California.
(c)    Business Days. Monday through Friday of each week in the calendar year,
excluding nationally recognized holidays and any days during Tenant's Observed
U.S. Winter and Summer Shutdowns.
(d)    Calendar Days. All the days of the calendar year, including weekends and
holidays, provided that, for purposes of this Workletter, Calendar Days shall
not include any days during Tenant's Observed U.S. Winter and Summer Shutdowns.
(e)    General Contractor. Any general contractor selected by Subtenant with the
prior written approval of Landlord and Tenant (which shall not be unreasonably
withheld, conditioned or delayed) with respect to Subtenant's Work. Landlord and
Tenant hereby agree that App Landmark Builders is a general contractor
reasonably acceptable to Landlord and Tenant and shall be deemed an approved
general contractor pursuant to this Paragraph 1(e).
(f)    Improvements. The construction of Subtenant Improvements and other
improvements shown on the Approved Plans from time to time and to be constructed
in the Building pursuant to this Workletter.

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(g)    Sublet Premises. The premises subleased by Subtenant pursuant to the
Sublease, as more particularly described in the Sublease.
(h)    Subtenant Improvements. The improvements within the Building, shown on
the Approved Plans from time to time and to be constructed by Subtenant pursuant
to the Sublease, Consent and this Workletter, including (but not limited to) the
improvements described in Schedule 1 attached to this Workletter.
(i)    Subtenant's Work. All of the Subtenant Improvements as Subtenant deems
necessary or appropriate for Subtenant's use and occupancy of the Building
pursuant to the Sublease.
(j)    Tenant's Observed U.S. Winter and Summer Shutdowns. The observed dates
during which Tenant shuts down its business operations in late December through
early January and on and around the 4th of July. Tenant confirms that Tenant's
Observed U.S. Winter and Summer Shutdowns are currently scheduled through
January 2019, as follows:
◦
July 2, 2016 through July 10, 2016

◦
December 23, 2016 through January 2, 2017

◦
July 1, 2017 through July 9, 2017

◦
December 22, 2017 through January 2, 2018

◦
June 30, 2018 through July 8, 2018

◦
December 22, 2018 through January 1, 2019

Upon request after they are scheduled, Tenant shall confirm the dates of
Tenant's Observed U.S. Winter Summer Shutdowns for later dates.
(k)    Unavoidable Delays. Delays due to acts of God, action or inaction of
public agencies, labor disputes, strikes, fires, freight embargoes, rainy,
stormy or other inclement weather (but only to the extent such weather prevents
the affected party from conducting any substantial element of its construction
work for a period of at least one full Business Day), inability to obtain
supplies, materials, fuels or permits, delays of contractors or subcontractors,
utility curtailments, or other causes or contingencies beyond the reasonable
control of Tenant or Subtenant, as applicable.
(l)    Cost of Improvements. The sum of the following (unless otherwise agreed
in writing by the relevant parties with respect to any specific item or
component or any category of items or components): (i) all sums paid to
contractors or subcontractors for labor and materials furnished in connection
with construction of such item or component; (ii) all costs, expenses, payments,
fees, taxes, levies and charges (other than penalties) paid or incurred to or at
the direction of any city, county or other governmental or quasi-governmental
authority or agency which are required to be paid in order to obtain all
necessary governmental permits, licenses, inspections and approvals relating to
construction of such item or component; (iii) engineering and architectural fees
for services rendered in connection with the design and construction of such
item or component

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(including, but not limited to, the Architect for such item or component and an
electrical engineer, mechanical engineer and civil engineer); (iv) sales and use
taxes; (v) testing and inspection costs; (vi) the cost of power, water and other
utility facilities and the cost of collection and removal of debris required in
connection with construction of such item or component; (vii) costs incurred for
the management and administration of the construction of the Subtenant
Improvements, including, without limitation, wages, labor burden, and
expediting, procurement and administrative expenses; and (viii) all other "hard"
costs incurred in the construction of such item or component in accordance with
the applicable Approved Plans and this Workletter.
(m)    Capitalized terms not otherwise defined in this Workletter shall have the
definitions set forth in the Sublease (or the Lease, as incorporated therein).
2.    Approved Plans. Landlord, Tenant and Subtenant shall comply with the
procedures set forth in this Paragraph 2 in preparing, delivering and approving
matters relating to the Subtenant Improvements.
(a)    Approved Plans and Working Drawings for Subtenant's Work. Subtenant shall
promptly and diligently cause to be prepared and delivered to Tenant, for
approval, a space plan and detailed plans and specifications for the Subtenant
Improvements constituting Subtenant's Work (the "Subtenant Plans"). Tenant shall
approve or disapprove of the Subtenant Plans, within ten (10) Calendar Days of
receipt thereof from Subtenant, which approval shall not be unreasonably
withheld, conditioned or delayed; provided, however, that should Tenant fail to
provide its written approval or disapproval of the Subtenant Plans within ten
(10) Calendar Days following Subtenant's delivery thereof, then Subtenant shall,
on or after such tenth (10th) Calendar Day, send Tenant a second written request
for approval, and if Tenant shall fail to provide its written approval or
disapproval of the Subtenant Plans within two (2) Business Days following
Subtenant's second request, then Tenant shall be deemed to have approved the
Subtenant Plans. Upon Tenant's approval or deemed approval, Tenant shall submit
the Subtenant Plans to Landlord for approval. Landlord shall approve or
disapprove of the Subtenant Plans within ten (10) Calendar Days of receipt by
Landlord of confirmation of Tenant's approval or deemed approval of such version
of the Subtenant Plans. If either Landlord or Tenant disapproves the Subtenant
Plans, such notice of disapproval shall include specific comments setting forth
the basis for such disapproval. Following approval of the Subtenant Plans by
both Landlord and Tenant (the Subtenant Plans as so approved, the "Approved
Plans"), Subtenant shall then cause to be prepared and delivered to Tenant, for
approval, final working drawings and specifications for the Subtenant
Improvements constituting Subtenant's Work, including any applicable life
safety, mechanical and electrical working drawings and final architectural
drawings (collectively, the "Final Working Drawings"). The Final Working
Drawings shall substantially conform to the Approved Plans. Tenant shall approve
or disapprove of the Final Working Drawings within ten (10) Calendar Days of
receipt thereof from Subtenant, which approval shall not be unreasonably
withheld, conditioned or delayed; provided, however, that should Tenant fail to
provide its written approval or disapproval of the Final Working Drawings within
ten (10) Calendar Days following Subtenant's delivery thereof, then Subtenant
shall, on or after such tenth (10th) Calendar Day, send Tenant a second written
request for approval, and if Tenant shall fail to provide its written approval
or disapproval of the Final Working Drawings within two (2) Business Days
following Subtenant's second request, then Tenant shall be deemed to have
approved the Final

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Working Drawings. Upon Tenant's approval or deemed approval, Tenant shall submit
the Final Working Drawings to Landlord for approval. Landlord shall approve or
disapprove of the Final Working Drawings within ten (10) Calendar Days of
receipt by Landlord of confirmation of Tenant's approval or deemed approval of
such version of the Final Working Drawings. Landlord and Tenant shall not
unreasonably withhold their respective approval of the Final Working Drawings;
provided, however, that Subtenant hereby agrees that it shall be deemed
reasonable for Landlord or Tenant to withhold approval of the Final Working
Drawings if a "Design Problem" exists or if the Final Working Drawings are not a
logical extension of the Approved Plans. A "Design Problem" shall mean and refer
to any design criteria which would (a) have an adverse effect on the Building
Shell or Improvements; (b) be in non-compliance with any applicable law; (c) can
be seen from the exterior of the Sublet Premises; (d) cause material
interference with other tenants of the Project; or (e) adversely affect the
certificate of occupancy issued for the Project. Upon approval of the Final
Working Drawings by both Landlord and Tenant, the Final Working Drawings shall
be deemed to be incorporated in and considered part of the Approved Plans,
superseding (to the extent of any inconsistencies) any inconsistent features of
the previously existing Approved Plans.
(b)    Landlord Approval Rights; Subtenant Security System. Without limiting the
breadth of the approval rights otherwise reserved to Landlord as set forth
above, Landlord reserves the right, in reviewing Subtenant's proposed drawings
and specifications pursuant to the terms of this Workletter, to require specific
modifications to the proposed Subtenant Improvements, at no additional cost to
Subtenant, in order to maintain or enhance flexibility with respect to other
potential future uses of the Building ("Landlord's Required Changes"). Landlord
has reviewed certain preliminary drawings dated January 7, 2016 (the
"Preliminary Plans") for the sole purpose of identifying any Landlord's Required
Changes. Landlord hereby notifies Subtenant that (i) the Subtenant Improvements
shown in the Preliminary Plans do not require any Landlord's Required Changes,
and (ii) to the extent the Subtenant Plans or Final Working Drawings contain
Subtenant Improvements that are not a logical extension of, or are not otherwise
clearly indicated in, the Preliminary Plans ("Newly Indicated SIs"),
concurrently with Landlord's approval of the Subtenant Plans and Final Working
Drawings, as applicable, Landlord shall notify Tenant whether any of the Newly
Indicated SIs will require any Landlord's Required Changes. For the avoidance of
doubt, Landlord has reviewed the Preliminary Plans solely for the purpose of
identifying any Landlord's Required Changes, and reserves all rights to review
and approve the Subtenant Plans and Final Working Drawings pursuant to the
provisions of this Workletter. Landlord's and Tenant's review of the Subtenant
Plans, the Approved Plans, and the Final Working Drawings (collectively, the
"Construction Documents") as set forth in this Section 2, shall be for each of
their respective sole purposes and shall not imply Landlord's or Tenant's review
of the same, or obligate Landlord or Tenant to review the same, for quality,
design, governmental or code compliance or other like matters. Accordingly,
notwithstanding that any Construction Documents are reviewed by Landlord or
Tenant, or their respective space planners, architects, engineers and
consultants, and notwithstanding any advice or assistance which may be rendered
to Subtenant by Landlord or Tenant or their respective space planners,
architects, engineers, and consultants, neither Landlord nor Tenant shall have
any liability whatsoever in connection therewith and shall not be responsible
for any omissions or errors contained in the Construction Documents. In
addition, Subtenant's waiver and indemnity set forth in Section 4.6 of the
Consent shall specifically apply to the Construction Documents; provided,
however, such waiver and indemnities shall not apply to any liability of

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Landlord, or damage suffered by Landlord, resulting from the design of any of
Landlord's Required Changes. Subtenant shall have the right to provide, install
and maintain, at its sole cost and expense, a security system (including,
without limitation, automatic door latches, card-key systems, etc.)
("Subtenant's Security System") in the Building. Subtenant shall provide
Landlord, Landlord's property manager, and Tenant with copies of any card-keys
or other required access devices in order to facilitate emergency entry by
Landlord, Tenant or their respective agents during the term of the Sublease,
subject to the provisions of Section 16.1 of the Original Lease, and Section
9.17 of the Sublease (as applicable).
(c)    Changes. If Subtenant at any time desires to make any changes,
alterations or additions to the Approved Plans, such changes, alterations or
additions shall be subject to approval by Landlord and Tenant in the same manner
as the original Approved Plans as provided above. Landlord shall bear all costs
and expenses that Subtenant may incur in connection with any Landlord's Required
Changes, and such amounts shall not be applied against any Allowance. Landlord
shall reimburse Subtenant for such costs and expenses, including any cost of
Improvements, within thirty (30) days after Landlord receives Subtenant's
invoice therefore.
(d)    Representatives and Responsibilities.
(i)    Landlord's Representative. Tenant shall coordinate with Project
Management Advisors, Inc. ("Landlord's Representative") (who shall have full
authority and responsibility to act on behalf of Landlord pursuant to this
Workletter) with regard to all approval and other rights of Landlord hereunder
and any logistical or coordination matters arising in connection with the
Subtenant Improvements or this Workletter. Landlord and Landlord's
Representative will interact with Subtenant directly as and to the extent
expressly set forth in this Workletter, but otherwise requests that all
interaction and coordination with Landlord and the Landlord's Representative
occur through the Tenant or Tenant's Representative. Landlord agrees to, and to
cause Landlord's Representative to agree to, respond to any approval requests by
Tenant (or Subtenant, when applicable) within the timeframes set forth herein.
Neither Tenant nor Subtenant shall be obligated to pay Landlord in connection
with Landlord's review and supervision of the Subtenant's Work or otherwise in
connection with Landlord's performance of the above obligations.
(ii)    Tenant's Representative. Tenant has designated Charles Barry ("Tenant's
Representative") as its sole representative with respect to the matters set
forth in this Workletter, who, until further notice to both Landlord and
Subtenant, shall have full authority and responsibility to act on behalf of the
Tenant as required in this Workletter. In addition, Tenant plans to hire
Landlord's Representative, Project Management Advisors, Inc., to advise and
consult with Tenant with regard to all matters covered by this Workletter and to
simplify the approval of plans and coordination of Subtenant's Work. Tenant
expressly acknowledges and agrees that, as between Tenant and Landlord, Tenant
remains fully liable for any Improvements installed in the Sublet Premises (by
Subtenant or otherwise) and Tenant's obligations under the Lease with respect
thereto remain in full force and effect, except as expressly modified by this
Workletter or the Consent. Tenant and/or Tenant's Representative agree to use
commercially reasonable efforts to respond to any approval requests by Subtenant
within the timeframes set forth herein. Subtenant shall not be

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obligated to pay Tenant in connection with Tenant's performance of its
obligations hereunder, including Tenant's review of the Subtenant's Work.
(iii)    Subtenant's Representative. Subtenant has designated Kevin J. Hickey as
its sole representative with respect to the matters set forth in this
Workletter, who, until further notice to Landlord and Tenant, shall have full
authority and responsibility to act on behalf of the Subtenant as required in
this Workletter.
(iv)    Notices. Notwithstanding the foregoing or anything to the contrary
herein, requests for consent or approvals hereunder must be sent in accordance
with the notice provisions set forth in the Consent to commence the time periods
for review and response set forth herein (provided that Tenant hereby notifies
Landlord and Subtenant that Tenant no longer maintains a fax number that can be
used for notice purposes and notices sent to Tenant by fax will not constitute
notice to Tenant). Without limiting the generality of the foregoing, it is
expressly understood that, while representatives identified herein are
authorized to provide approvals from the party they are representing, requests
for approvals or other notices sent solely to a party's representative (without
also sending such requests or notices in compliance with the notice provisions
of the Consent) shall not constitute notice under this Workletter or commence
the applicable time period for completing such party's review.
3.    [Intentionally Omitted]
4.    Payment of Costs; Allowances. The cost of construction of Subtenant's Work
shall be borne by Subtenant at its sole cost and expense, including any costs or
cost increases incurred as a result of Unavoidable Delays, governmental
requirements or unanticipated conditions. Notwithstanding the foregoing, it is
acknowledged that (a) Tenant is providing Subtenant an allowance (the "Subtenant
Improvement Allowance") to apply towards Subtenant's costs to construct the
Subtenant Improvements, as more particularly set forth in the Sublease (which
shall govern the disbursement of the Subtenant Improvement Allowance for all
purposes); and (b) Tenant has agreed to provide to Subtenant the benefit of, and
shall be responsible to disburse to Subtenant pursuant to the terms of the
Sublease and this Workletter, the remaining portion of the allowance funds
available to Tenant under the Lease with respect to the Sublet Premises (the
"Master Lease Allowance") on the terms set forth in Section 7 below.
5.    Subtenant's Work. Subtenant shall construct and install in the Building
the Subtenant's Work, substantially in accordance with the Approved Plans or,
with respect to Subtenant's Work not otherwise shown on the Approved Plans,
substantially in accordance with plans and specifications prepared by Subtenant
and approved in writing by both Landlord and Tenant (which approval shall not be
unreasonably withheld, conditioned or delayed). Subtenant's Work shall be
performed in accordance with, and shall in all respects be subject to, the terms
and conditions of the Lease other than the terms of Exhibit C thereto (to the
extent not inconsistent with this Workletter), and shall also be subject to the
following conditions:
(a)    Contractor Requirements. The contractor engaged by Subtenant for
Subtenant's Work, and any subcontractors, shall be duly licensed in California
and shall be subject to Tenant's and Landlord's prior written approval, which
approval shall not be unreasonably withheld,

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conditioned or delayed. Subtenant shall engage only union contractors for the
construction of Subtenant's Work and for the installation of Subtenant's
fixtures and equipment in the Building, and shall require all such contractors
engaged by Subtenant, and all of their subcontractors, to use only union labor
on or in connection with such work, except to the extent Landlord determines, in
its reasonable discretion, that the use of non-union labor would not create a
material risk of labor disputes, picketing or work interruptions at the
Property, in which event Landlord shall, to that extent, waive such union labor
requirement. Landlord hereby waives the union labor requirement for Subtenant's
contractors, App Landmark Builders, Howell Electric, and InsideSource, and for
all subcontractors of such contractors, subject to Subtenant's compliance with
any reasonable rules and regulations that Landlord may implement to minimize
disruption as a result thereof, including, without limitation, requirements that
non-union contractors and subcontractors use a different gate or access point to
the Sublet Premises than union members.
(b)    Costs and Expenses of Subtenant's Work. Without limiting (i) Tenant's
obligation to fund the Subtenant Improvement Allowance and to disburse the
Master Lease Allowance in accordance with the terms and conditions set forth in
the Sublease and this Workletter, as applicable, or (ii) Landlord's obligation
to fund to Tenant the Master Lease Allowance in accordance with the terms and
conditions of the Lease, as modified by Section 7 below, Subtenant shall timely
pay all costs and expenses arising out of the performance of Subtenant's Work
(including the costs of permits) and shall furnish Tenant and Landlord with
evidence of payment on request. Subtenant shall provide Landlord and Tenant with
seven (7) Calendar Days' prior written notice before commencing any Subtenant's
Work. On completion of Subtenant's Work, Subtenant shall deliver to each of
Landlord and Tenant a release and unconditional lien waiver executed by (a) each
contractor and subcontractor that performed any of Subtenant's Work, and (b) any
materialman that has lien rights with respect to Subtenant's Work. If any lien
is filed against the Property or any portion thereof or against Subtenant's
leasehold interest as a result of the construction of any Subtenant Improvements
or other actions taken by Subtenant or its agents, employees or contractor,
Subtenant shall obtain, within ten (10) Calendar Days after Subtenant is
notified of the filing, the release or discharge of that lien. If Subtenant
fails to do so, Landlord and Tenant shall each have the right (but not the
obligation) to obtain the release or discharge of the lien and Subtenant shall,
within fifteen (15) Calendar Days after written demand by Landlord or Tenant (as
applicable, and accompanied by reasonable documentation of the items claimed),
reimburse Landlord or Tenant for all costs, including (but not limited to)
reasonable attorneys' fees, incurred by Landlord or Tenant (as the case may be)
in obtaining the release or discharge of such lien, together with interest from
the date of demand at the interest rate set forth in Section 3.2 of the Original
Lease.
(c)    Indemnification. Subtenant shall indemnify, defend (with counsel
satisfactory to Landlord or Tenant, as applicable) and hold Landlord and Tenant
and their respective agents and employees harmless from all suits, claims,
actions, losses, costs and expenses (including, but not limited to, claims for
workers' compensation, attorneys' fees and costs) based on personal injury or
property damage or contract claims (including, but not limited to, claims for
breach of warranty) arising from the performance of Subtenant's Work, other than
those resulting from the negligence or willful misconduct or omission by
Landlord or Tenant or any of their agents, employees or contractors. Subtenant
shall repair or replace (or, at the election of the party incurring the expense,
reimburse Landlord or Tenant for the cost of repairing or replacing) any portion
of the Building

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and/or any of Landlord's or Tenant's real or personal property or equipment that
is damaged, lost or destroyed in the course of or in connection with the
performance of Subtenant's Work.
(d)    Insurance. Subtenant's contractors shall obtain and provide to Tenant and
Landlord certificates evidencing workers' compensation, public liability,
property damage, and with respect to contractors providing construction
workmanship or materials, "Builder's All Risk" insurance in amounts and forms
and with companies reasonably satisfactory to Landlord and Tenant and shall name
each of Landlord and its agents (specifically including HCP Life Science REIT,
Inc., HCP, Inc., CBRE, Inc., Project Management Advisors, Inc., and HCP BTC,
LLC) and Tenant as additional insureds. All such policies of insurance must
contain a provision that the company writing said policy will give Landlord and
Tenant thirty (30) Calendar Days' prior written notice of any cancellation or
lapse of the effective date or any reduction in the amounts of such insurance.
All insurance, except workers' compensation, maintained by Subtenant shall
preclude subrogation claims by the insurer against anyone insured thereunder.
Such insurance shall provide that it is primary insurance as respects Landlord
and Tenant and that any other insurance maintained by Landlord or Tenant is
excess and noncontributing with the insurance required of Subtenant hereunder.
(e)    Rules and Regulations. Subtenant and Subtenant's contractors shall comply
with Landlord's rules, regulations and requirements with respect to the
performance of Subtenant's Work. Subtenant's agreement with Subtenant's
contractors shall require each contractor to reasonably clean up, in accordance
with industry standards applicable to construction projects at first-class
buildings, the construction area to the extent that such cleanup is necessitated
by the performance of Subtenant's Work. Commencing upon the execution of the
Sublease, Subtenant shall hold regularly scheduled formal meetings with
Architect and General Contractor regarding the progress of the preparation of
Construction Documents and the construction of the Subtenant Improvements.
Subtenant shall inform Landlord and Tenant of the time and location of such
meetings and Landlord and Tenant shall have the right to attend any such
meetings. Such meetings shall be held at 650 Gateway Boulevard, South San
Francisco, California 94080, or at the Sublet Premises, but Subtenant shall also
provide the option to participate in such meetings by phone. Subtenant shall
provide customary meeting minutes of all such meetings to Landlord and Tenant.
(f)    Risk of Loss. All materials, work, installations and decorations of any
nature brought onto or installed in the Building, by or at the direction of
Subtenant or in connection with the performance of Subtenant's Work shall be at
Subtenant's risk, and neither Landlord, Tenant nor any party acting on
Landlord's or Tenant's behalf shall be responsible for any damage, loss or
destruction thereof. Each of Subtenant's agents and contractors providing
construction workmanship or materials (including the General Contractor, but
excluding the Architect) shall warrant to Subtenant and for the benefit of
Landlord and Tenant that the portion of the Subtenant Improvements for which it
is responsible shall be free from any defects in workmanship and materials for a
period of not less than one (1) year from the date of substantial completion
thereof. Each of Subtenant's agents and contractors providing construction
workmanship or materials shall be responsible for the replacement or repair,
without additional charge, of all work done or furnished in accordance with its
contract if such contractor or subcontractor is notified that such work is
defective within one (1) year after substantial completion of the work performed
by such contractor or subcontractors. The

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correction of such work shall include, without additional charge, all additional
expenses and damages incurred in connection with such removal or replacement of
all or any part of the Subtenant Improvements, and/or the Building and/or common
areas that may be damaged or disturbed thereby. All such warranties or
guarantees as to materials or workmanship of or with respect to the Subtenant
Improvements shall be contained in each of Subtenant's agent's contracts or
subcontracts and shall be written such that such guarantees or warranties shall
inure to the benefit of Landlord, Tenant, and Subtenant, as their respective
interests may appear, and can be directly enforced by any of them. Subtenant
covenants to give to Landlord and Tenant, as applicable, any commercially
reasonable assignment or other commercially reasonable assurances which may be
necessary to effect such right of direct enforcement.
(g)    Condition of Subtenant's Work. All work performed by Subtenant shall be
performed in a good and workmanlike manner, shall be free from defects in
design, materials and workmanship, and shall be completed in compliance with the
Approved Plans in all material respects and in compliance with all applicable
governmental laws, ordinances, codes and regulations in force at the time such
work is completed. Without limiting the generality of the foregoing, Subtenant
shall be responsible for compliance of all Subtenant Improvements designed and
constructed by Subtenant with the requirements of the Americans with
Disabilities Act and all similar or related requirements pertaining to access by
persons with disabilities. Landlord and Tenant shall each have the right to
inspect the Subtenant Improvements subject to the terms of Section 16.1 of the
Lease, as incorporated into the Sublease, provided however, that Landlord's or
Tenant's failure to inspect the Subtenant Improvements shall in no event
constitute a waiver of any of Landlord's or Tenant's rights hereunder nor shall
Landlord's or Tenant's inspection of the Subtenant Improvements constitute
Landlord's or Tenant's approval of the same. Should Landlord disapprove any
portion of the Subtenant Improvements, Landlord shall notify Tenant (or, at
Landlord's option, Landlord may directly notify Subtenant) in writing of such
disapproval and shall specify the items disapproved. Should Tenant disapprove
any portion of the Subtenant Improvements, or should Tenant receive notice of
Landlord's disapproval pursuant to the previous sentence, Tenant shall notify
Subtenant (on behalf of Landlord and/or Tenant, as applicable) in writing of
such disapproval and shall specify the items disapproved. Notwithstanding
anything to the contrary herein, however, Landlord and Tenant shall have the
right to disapprove of the Subtenant Improvements only to the extent the
Subtenant Improvements (i) do not materially comply with the Approved Plans,
(ii) do not comply with applicable laws, rules or regulations, or (iii) were not
completed in a good and workmanlike manner (any such notice, the "Disapproval
Notice"). Following the receipt of a valid Disapproval Notice, Subtenant shall
rectify such matters set forth in the Disapproval Notice meeting the above
criteria at no expense to Landlord or Tenant, provided however, that should
Subtenant fail to rectify such matters within thirty (30) Calendar Days
following the receipt of a valid Disapproval Notice, then Landlord or Tenant may
take such action as Landlord or Tenant deem reasonably necessary, at Subtenant's
expense and without incurring any liability on Landlord's or Tenant's part, to
correct such matters, including, without limitation, causing the cessation of
performance of the construction of the Subtenant Improvements until such time as
such matters are corrected.

6.    [Intentionally Deleted].

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7.    Disbursement of Master Lease Allowance. Landlord and Tenant acknowledge
and agree that the remaining Master Lease Allowance (which the parties agree is
an amount equal to $2,204,830.49 as of the date hereof) may be used for
improvements in the Sublet Premises, including the Subtenant Improvements, in
accordance with the terms of the Lease. Tenant shall have the right to receive
reimbursement directly from Landlord (as opposed to Landlord directly paying
Subtenant or any applicable contractors, subcontractors, materialmen or agents
of Tenant or Subtenant) for funds actually disbursed by Tenant to Subtenant for
the Cost of Improvement (as defined in the Lease) incurred in connection with
the Subtenant Improvements and otherwise subject to, and in accordance with, the
requirements of the Lease, up to the remaining amount of the Master Lease
Allowance.
8.    Removable Property. Section 11.2 of the Original Lease shall apply with
respect to Subtenant's rights and obligations with respect to the removal of the
Subtenant Improvements and restoration of the Sublet Premises. Notwithstanding
the foregoing, Subtenant shall not be required to remove Subtenant's Security
System from the Sublet Premises upon expiration or earlier termination of the
Sublease. Subtenant's Security System shall be surrendered to Landlord in the
condition required for such surrender set forth in the Lease. Subtenant shall
not be obligated to install or construct any Subtenant Improvements on the
second (2nd) floor of the Sublet Premises; provided, however, that if
construction of any Subtenant Improvements on the second (2nd) floor of the
Sublet Premises is commenced (excluding any Subtenant Improvements that are on
or within the second (2nd) floor of the Sublet Premises, but required solely in
connection with, or otherwise relate to, Subtenant Improvements on other floors
of the Sublet Premises, such as HVAC or electrical work), such Subtenant
Improvements shall be diligently pursued to completion. For the avoidance of
doubt, the foregoing shall not limit Tenant's (or Subtenant's) obligations on
the second (2nd) floor of the Sublet Premises with respect to repair,
maintenance, compliance with laws and similar obligations under the Lease (and
Sublease).
9.    Notice of Completion. Within ten (10) Calendar Days after the final
completion of construction of the Subtenant Improvements, including, without
limitation, the completion of any punch list items, Subtenant shall cause a
Notice of Completion to be recorded in the office of the Recorder of the County
of San Mateo in accordance with Section 8182 of the Civil Code of the State of
California or any successor statute, and shall furnish a copy thereof to
Landlord and Tenant upon such recordation. If Subtenant fails to do so, either
Landlord or Tenant may execute and file the same on behalf of Subtenant as
Subtenant's agent for such purpose, at Subtenant's sole cost and expense.
10.    No Agency. Nothing contained in this Workletter shall make or constitute
Subtenant as the agent of Landlord or Tenant. Nothing contained in this
Workletter shall make or constitute Tenant as the agent of Landlord.
11.    Survival. Without limiting survival provisions which would otherwise be
implied or construed under applicable law, the provisions of Paragraph 5(c) of
this Workletter shall survive the termination of the Lease, Sublease, and
Consent with respect to matters occurring prior to expiration of the Lease,
Sublease or Consent, as the case may be.

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12.    Time Is Of Essence. Time is of essence in respect of each and every term,
covenant and condition of this Workletter.
13.    Miscellaneous. All references in this Workletter to a number of days
shall be construed to refer to Calendar Days, unless otherwise specified herein.
[SIGNATURES ARE ON NEXT PAGE]

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IN WITNESS WHEREOF, the parties have executed this Workletter concurrently with
and as of the date of the Consent.
LANDLORD:
HCP BTC, LLC,
a Delaware limited liability company
By: HCP Estates USA Inc.,
          a Delaware corporation
          By: /s/ Jonathan Mr. Bergschneider
                      Jonathan M. Bergschneider
                      Executive Vice President

TENANT:
AMGEN INC.,
a Delaware corporation
By: /s/ David Meline
Name: David Meline
Its: Executive Vice President and
       Chief Financial Officer

SUBTENANT:
PROTHENA BIOSCIENCES INC, 
a Delaware corporation
By: /s/ Tran Nguyen
Name: Tran Nguyen          
Its: CFO
By: /s/ A. W. Homan
Name: A. W. Homan
Its: CLO & Secretary
 
 

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Schedule l to Workletter
SUBTENANT IMPROVEMENTS DESCRIPTION
The "Subtenant Improvements" as defined in the Workletter to which this
Schedule 1 is attached and in the Workletter described therein shall include,
but not necessarily be limited to, the following:
All tenant construction, fixtures, furnishings, etc. to support tenant
operations, including, without limitation, use space, offices, lobbies,
circulation, restrooms, and all other features, including security systems, not
specifically identified as being part of the Warm Shell Condition described in
Exhibit C attached to the Sublease.
"Subtenant Improvements" shall not include the design and/or construction of
infrastructure, landscaping or other site improvements unless specifically
requested by Subtenant or as a result of Subtenant Improvements or Subtenant's
requested modifications to existing improvements.

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