Document:

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                                                                   EXHIBIT 10.17

                                                May 6, 2005

Mr. Sheldon Berkle
450 Terracina Lane
Naples, FLA 34119

Dear Shelly:

We are very pleased to extend an offer for you to join Altus Pharmaceuticals
Inc. ("Altus" or the "Company") as President, Chief Executive Officer and a
member of the Board of Directors. Through the discussions the Board of Directors
has had with you during the interview process, we have been impressed with your
substantial pharmaceutical industry experience, track record of accomplishments,
strong business intellect, and overall leadership skills. Our impressions have
been reinforced by the extremely positive set of reference calls that we also
conducted. We believe you are well qualified to assume the Chief Executive
Officer role at Altus and have every confidence that you will be successful in
this capacity.

Commensurate with this position, the Board is prepared to offer you an
exceptional compensation package. The position provides an annualized base
salary of $400,000 which will be paid on a biweekly basis. In addition to your
base salary, you will have the opportunity to earn an annual performance bonus
of up to 50% of your earned salary based on achievement of a series of personal
and Company objectives that the Board of Directors and you will define annually.
For 2005, objectives will be recommended by you for the Board's review and
approval within thirty days after the Commencement Date (as defined below). The
2005 performance bonus will be awarded based on achievement against these
objectives and prorated based on the Commencement Date.

You will begin employment as Altus' President and Chief Executive Officer on May
9, 2005 (the "Commencement Date"), working two days per week through May 31 in
order to accelerate your transition. During this period you will be paid at the
rate of two-fifths of your base salary. Starting on June 1, 2005, your work
schedule will shift to full-time, and your salary will commensurately increase.

You will also be eligible for a $150,000 loan from the Company on the
Commencement Date. Based on your continued employment, the loan will be forgiven
as to $75,000 on each of the first and second anniversaries of the Commencement
Date. Should you voluntarily terminate your employment before either
anniversary, the outstanding loan amount as of that date will be repaid by you
to the Company. Please note that if you resign for good reason (as defined
below), it will not be considered a voluntary termination by you of your
employment, and you will have no repayment obligation.
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Mr. Sheldon Berkle
May 6, 2005
Page 2 of 16

You will also have no repayment obligation if your employment is terminated by
Altus, except if such termination is for cause (as defined below).

You will also be entitled to 12 months severance at a rate equal to your
then-current base salary in the event that (1) Altus terminates your employment
without cause or you resign for good reason, or (2) you resign for good reason
within 6 months after a change in control (as defined below). The Company will
also, in such circumstances, assume payments under your house and automobile
leases in the Boston area for the 12-month severance period (or, if shorter,
until the expiration of the respective terms of such leases), up to an aggregate
of $25,000.

The President and Chief Executive Officer position provides you an initial grant
of stock options exercisable for a total of 1,300,000 shares of common stock at
an exercise price of $1.71 per share, the fair market value of Altus' common
stock on the Commencement Date. This is a significant equity award and should be
viewed as a source of substantial long-term wealth creation potential assuming
you achieve success in leading the Company. One quarter of the options will vest
on the first anniversary of the Commencement Date. After this time, an
additional 1/48th of the total underlying option grant will vest on a monthly
basis, such that all the options will be vested after four years. The options
will have a ten-year term and will be subject to customary terms and conditions
set forth in a stock option agreement that we will provide you. In addition to
this initial grant, the Board of Directors would also plan to make annual stock
option grants to you based on the performance of the Company.

Your employment will be subject to employee non-disclosure and inventions
assignment covenants, as well as non-competition and non-solicitation covenants,
as set forth in the agreement annexed to this letter as Appendix A.

In addition to this compensation, you will be entitled to 5 weeks of paid
vacation annually, together with standard employee benefits which may be changed
from time to time as the Company deems appropriate. A description of current
benefits is set forth on Appendix B to this letter for your information.

As used in this letter, "cause" and "change in control" have the meanings set
forth in Altus' 2002 Employee, Director and Consultant Stock Plan. Those
definitions are set forth in Appendix C to this letter. The definition of for
"good reason" is also set forth in Appendix C.
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Mr. Sheldon Berkle
May 6, 2005
Page 3 of 16

We hope you find the Altus offer and position attractive and look forward to
your favorable response. Please return one copy of this letter indicating your
acceptance by May 9, 2005.

                                             Sincerely,

                                             /s/ John Richard

                                             John Richard
                                             Chairman of the Board

I accept the terms of employment offered in this letter.

Signature:  /s/ Sheldon Berkle                Date:  May 10, 2005
            -------------------------------          ----------------------
            Sheldon Berkle
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Mr. Sheldon Berkle
May 6, 2005
Page 4 of 16

                                   APPENDIX A

                                                May 6, 2005

Mr. Sheldon Berkle
450 Terracina Lane
Naples, FL 34119

            Re:  Non-Competition, Non-Solicitation, Non-Disclosure, Assignment
of Inventions

Dear Sheldon:

This letter is to confirm our understanding with respect to certain conditions
to your employment by Altus Pharmaceuticals Inc. (the "Company"), including (i)
your agreement not to compete with the Company, or any present or future parent,
subsidiary or affiliate of the Company (collectively with the Company, the
"Company Group"), (ii) your agreement to protect and preserve information and
property which is confidential and proprietary to the Company Group and (iii)
your agreement with respect to the ownership of inventions, ideas, copyrights
and patents which may be used in the business of the Company Group (the terms
and conditions agreed to in this letter are hereinafter referred to as the
"Agreement"). In consideration of the mutual promises and covenants contained in
this Agreement, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby mutually acknowledged, we have agreed as
follows:

1.    Prohibited Competition.

            (a) Certain Acknowledgements and Agreements.

                  (i) We have discussed, and you recognize and acknowledge, the
      competitive and proprietary aspects of the business of the Company Group.

                  (ii) You acknowledge that a business will be deemed
      competitive with the Company Group if it engages in a business activity
      which is, directly or indirectly, related to the research, development,
      manufacture, marketing, selling or servicing of products or services that
      are competitive with or otherwise similar to the products or services
      being marketed, sold, serviced or under development or consideration by or
      on behalf of the Company Group, including, but not limited to, services
      and products related to the crystallization of proteins, antibodies or any
      other matter.
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Mr. Sheldon Berkle
May 6, 2005
Page 5 of 16

                  (iii) You further acknowledge that, while you are employed by
      the Company, the Company Group will furnish, disclose or make available to
      you Confidential Information (as defined below) related to the business of
      the Company Group and that the Company Group may provide you with unique
      and specialized training. You also acknowledge that such Confidential
      Information and such training have been developed and will be developed by
      the Company Group through the expenditure by the Company Group of
      substantial time, effort and money and that all such Confidential
      Information and training could be used by you to compete with the Company
      Group. You also acknowledge that if you become employed or affiliated with
      any competitor of the Company Group in violation of your obligations in
      this Agreement, it is inevitable that you would disclose the Confidential
      Information to such competitor and would use such Confidential
      Information, knowingly or unknowingly, on behalf of such competitor.
      Further, while you are employed by the Company, you will be introduced to
      customers and others with important relationships to the Company Group.
      You acknowledge that any and all "goodwill" created through such
      introductions belongs exclusively to the Company Group, including, without
      limitation, any goodwill created as a result of direct or indirect
      contacts or relationships between yourself and any strategic partners,
      research and development collaborators, customers, patrons, vendors and
      suppliers of the Company Group.

                  (iv) For purposes of this Agreement, "Confidential
      Information" means confidential and proprietary information of the Company
      Group, whether in written, oral, electronic or other form, including but
      not limited to, any and all versions of the Company Group's proprietary
      pharmaceutical systems, data and documentation, all proprietary computer
      system software, firmware, data, documentation and information now or
      later created, developed, produced or marketed by the Company Group, or
      any other information and facts concerning business plans, customers,
      future customers, suppliers, licensors, licensees, partners,
      collaborators, investors, affiliates or others, training methods and
      materials, financial information, sales prospects, client lists,
      inventions, or any other scientific, technical or trade secrets of the
      Company Group or of any third party provided to you or the Company Group
      under a condition of confidentiality, provided that Confidential
      Information will not include information that is in the public domain
      other than through any fault or act by you. The term "trade secrets," as
      used in this Agreement, will be given its broadest possible interpretation
      under the law of the Commonwealth of Massachusetts and will include,
      without limitation, anything tangible or intangible or electronically kept
      or stored, which constitutes, represents, evidences or records secret,
      scientific, technical, merchandising, production or management
      information, or any design, process, procedure, formula, invention,
      improvement or other confidential or proprietary information or documents.

            (b) Non-Competition; Non-Solicitation. While you are employed by the
Company and for a period of twelve (12) months following the termination of your
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Mr. Sheldon Berkle
May 6, 2005
Page 6 of 16

employment by the Company for any reason or for no reason, you will not, without
the prior written consent of the Company:

                  (i) For yourself or on behalf of any other person or entity,
      directly or indirectly, either as principal, partner, stockholder,
      officer, director, member, employee, consultant, agent, representative or
      in any other capacity, own, manage, operate or control, or be connected
      with or employed by, or otherwise associate in any manner with, engage in
      or have a financial interest in, any business or business activity which
      is related to the research, development, manufacture, marketing, selling
      or servicing of products or services that are competitive with the
      products or services being marketed, sold, serviced or under active
      development or serious consideration by or on behalf of the Company Group
      anywhere in the world, including, but not limited to, services and
      products related to the crystallization of proteins, antibodies or any
      other matter, except that nothing contained herein will preclude you from
      purchasing or owning securities of any such business if such securities
      are publicly traded, and provided that your holdings do not exceed one
      percent (1%) of the issued and outstanding securities of any class of
      securities of such business; or

                  (ii) Either individually or on behalf of or through any third
      party, directly or indirectly, solicit, divert or appropriate, or attempt
      to solicit, divert or appropriate, for the purpose of competing with or
      disrupting the relationship with the Company Group, any persons or
      entities that are, or were, partners, collaborators, customers, patrons,
      vendors or suppliers of the Company Group, or any prospective partners,
      collaborators, customers, patrons, vendors or suppliers with respect to
      which the Company Group has developed or made a presentation or engaged in
      substantive discussions concerning establishing a relationship material to
      the Company Group; or

                  (iii) Either individually or on behalf of or through any third
      party, directly or indirectly, (A) hire, retain, solicit, entice,
      encourage or persuade, or attempt to hire, retain, solicit, entice,
      encourage or persuade, any director or employee of, or consultant to, the
      Company Group to leave the service of the Company Group for any reason, or
      (B) employ, cause to be employed, or solicit the employment or service of,
      any director or employee of, or consultant to, the Company Group, in each
      case while any such person is providing services to the Company Group or
      within six months after any such person has ceased providing services to
      the Company Group; or

                  (iv) Either individually or on behalf of or through any third
      party, directly or indirectly, interfere with, or attempt to interfere
      with, the relations between the Company Group and any partner,
      collaborator, customer, patron, vendor or supplier of the Company Group.

            (c) Reasonableness of Restrictions. You further recognize and
acknowledge that (i) the types of employment which are prohibited by this
Section 1 are narrow and reasonable in relation to the skills which represent
your principal salable asset both to the Company Group and to your other
prospective employers and (ii) the time
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 7 of 16

period and the geographical scope of the provisions of this Section 1 are
reasonable, legitimate and fair to you in light of the Company Group's need to
pursue its business objectives and relationships, including, but not limited to,
its therapeutic product research and development efforts and the establishment
of collaborative partnerships, and in light of the limited restrictions on the
type of employment prohibited herein compared to the types of employment for
which you are qualified to earn your livelihood.

            (d) Survival of Acknowledgements and Agreements. Your
acknowledgements and agreements set forth in this Section 1 will survive the
termination of this Agreement and the termination of your employment by the
Company for any reason or for no reason.

2.    Protected Information. You will at all times, both during the period while
you are employed by the Company and after the termination of this Agreement and
the termination of your employment by the Company for any reason or for no
reason, maintain in confidence and will not, without the prior written consent
of the Company Group, use, except as required in the course of performance of
your duties for the Company Group or by court order, disclose or give to others
any Confidential Information. Upon the termination of your employment by the
Company for any reason or for no reason, or if the Company Group otherwise
requests, you will return to the Company Group all tangible Confidential
Information and copies thereof (regardless how such Confidential Information or
copies are maintained, including whether or not in electronic form or
otherwise). The terms of this Section 2 are in addition to, and not in lieu of,
any statutory or other contractual or legal obligation that you may have
relating to the protection of the Company Group's Confidential Information. The
terms of this Section 2 will survive indefinitely any termination of this
Agreement and/or any termination of your employment by the Company for any
reason or for no reason.

3.    Ownership of Ideas, Copyrights and Patents.

            (a) Property of the Company. You acknowledge and agree that all
ideas, discoveries, creations, manuscripts and properties, innovations,
improvements, know-how, inventions, designs, developments, apparatus,
techniques, methods, biological processes, cell lines, laboratory notebooks and
formulae (collectively, the "Inventions") which may be used in the current or
planned business of the Company Group or which in any way relates to such
business, whether patentable, copyrightable or not, which you may conceive,
reduce to practice or develop while you are employed by the Company (and, if
based on or related to any Confidential Information, within two years after
termination of such employment for any reason or for no reason), alone or in
conjunction with another or others, whether during or out of regular business
hours, whether or not on the Company Group's premises or with the use of its
equipment, and whether at the request or upon the suggestion of the Company
Group or otherwise, will be the sole and exclusive property of the Company
Group, and you will not publish any of the Inventions without the prior written
consent of the Company Group. Without limiting the foregoing,
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 8 of 16

you also acknowledge and agree that all original works of authorship which are
made by you (solely or jointly with others) within the scope of your employment
or which relate to the business of the Company Group and which are protectable
by copyright are "works made for hire" pursuant to the United States Copyright
Act (17 U.S.C. Section 101). You hereby assign to the Company Group all of your
right, title and interest in and to all of the foregoing. You further represent
that, to the best of your knowledge and belief, none of the Inventions will
violate or infringe upon any right, patent, copyright, trademark or right of
privacy, or constitute libel or slander against or violate any other rights of
any person, firm or corporation, and that you will use your best efforts to
prevent any such violation.

            (b) Cooperation. At any time during your employment by the Company
or after the termination of your employment by the Company for any reason or for
no reason, you will cooperate fully with the Company Group and its attorneys and
agents in the preparation and filing of all papers and other documents as may be
required to perfect the Company Group's rights in and to any of such Inventions,
including, but not limited to, joining in any proceeding to obtain letters
patent, copyrights, trademarks or other legal rights with respect to any such
Inventions in the United States and in any and all other countries, provided
that the Company Group will bear the expense of such proceedings, and that any
patent or other legal right so issued to you personally will be assigned by you
to the Company Group without charge by you.

            (c) Licensing and Use of Inventions. With respect to any Inventions,
and work of any similar nature (from any source), whenever created, which you
have not prepared or originated in the performance of your employment, but which
you provide to the Company Group or incorporate in any Company Group product or
system, you hereby grant to the Company Group a royalty-free, fully paid-up,
non-exclusive, perpetual and irrevocable license throughout the world to use,
modify, create derivative works from, disclose, publish, translate, reproduce,
deliver, perform, and dispose of, all such Inventions, and to authorize others
to do so. You will not include in any Inventions you deliver to the Company
Group or use on its behalf, without the prior written approval of the Company
Group, any material which is or will be patented, copyrighted or trademarked by
you or others unless you provide the Company Group with the written permission
of the holder of any patent, copyright or trademark owner for the Company Group
to use such material in a manner consistent with then-current Company Group
policy.

            (d) Prior Inventions. Listed on Exhibit 3(d) to this Agreement are
any and all Inventions in which you claim or intend to claim any right, title
and interest (collectively, "Prior Inventions"), including, without limitation,
patent, copyright and trademark interests, which to the best of your knowledge
will be or may be delivered to the Company Group in the course of your
employment, or incorporated into any Company Group product or system. You
acknowledge that your obligation to disclose such information is ongoing while
you are employed by the Company.
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 9 of 16

4.    Disclosure to Future Employers. You will provide, and the Company, in its
discretion, may similarly provide, a copy of the covenants contained in Sections
1, 2 and 3 of this Agreement to any business or enterprise which you may,
directly or indirectly, own, manage, operate, finance, join, control, or in
which you may participate in the ownership, management, operation, financing, or
control, or with which you may be connected as an officer, director, employee,
partner, principal, agent, representative, consultant or otherwise.

5.    Records. Upon termination of your employment by the Company for any reason
or for no reason and at any other time requested by the Company, you will
deliver to the Company Group any property of the Company Group which may be in
your possession, including products, materials, memoranda, notes, records,
reports, or other documents or photocopies of the same (regardless of how they
are maintained, including whether or not in electronic form).

6.    Assignment. This Agreement will be binding upon and inure to the benefit
of (a) your heirs, executors and legal representatives upon your death and (b)
any successor of the Company. Any such successor of the Company will be deemed
substituted for the Company under the terms of this Agreement for all purposes.
For this purpose, "successor" means any person, firm, corporation or other
business entity which at any time, whether by purchase, merger or otherwise,
directly or indirectly acquires all or substantially all of the assets or
business of the Company. None of your rights to receive any form of compensation
payable pursuant to this Agreement may be assigned or transferred except by will
or the laws of descent and distribution. Any other attempted assignment,
transfer, conveyance or other disposition of your right to compensation or other
benefits will be null and void.

7.    Notices. All notices, requests, demands and other communications called
for hereunder will be in writing and will be deemed given (a) on the date of
delivery if delivered personally, (b) one (1) day after being sent by a well
established commercial overnight service, or (c) four (4) days after being
mailed by registered or certified mail, return receipt requested, prepaid and
addressed to the parties or their successors at the following addresses, or at
such other addresses as the parties may later designate in writing:

If to the Company:
      Altus Pharmaceuticals Inc.
      125 Sidney Street
      Cambridge, MA 02139
      Attn: Chairman of the Board
With a copy to:
      Jonathan L. Kravetz, Esq.
      Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 10 of 16

      One Financial Center
      Boston, MA 02111

If to you:

At your home address as listed in your personnel file at the Company from time
to time

8.    Representations. You hereby represent and warrant to the Company that you
understand this Agreement, that you enter into this Agreement voluntarily and
that your employment by the Company will not conflict with any legal duty owed
by you to any other party, or with any agreement to which you are a party or by
which you are bound, including, without limitation, any non-competition or
non-solicitation provision contained in any such agreement. You will indemnify
and hold harmless the Company Group and its officers, directors, security
holders, partners, members, employees, agents and representatives against loss,
damage, liability or expense arising from any claim based upon circumstances
alleged to be inconsistent with such representation and warranty.

9.    Entire Agreement. This Agreement represents the entire agreement and
understanding between you and the Company concerning the subject matter herein,
and supersedes and replaces any and all prior or contemporaneous agreements and
understandings whether written or oral between you and the Company concerning
the subject matter herein.

10.   Injunctive Relief. You hereby expressly acknowledge that any breach or
threatened breach of any of the terms and/or conditions set forth in Section 1,
2 or 3 of this Agreement will result in substantial, continuing and irreparable
injury to the Company Group. Therefore, in addition to any other remedy that may
be available to the Company Group, the Company Group will be entitled to
injunctive or other equitable relief by a court of appropriate jurisdiction in
the event of any breach or threatened breach of the terms of Section 1, 2 or 3
of this Agreement. The period during which the covenants contained in Section 1
will apply will be extended by any periods during which you are found by a court
to have been in violation of such covenants.

11.   Arbitration. Any controversy, dispute or claim arising out of or in
connection with this Agreement, other than a controversy, dispute or claim
arising under Section 1, 2 or 3 hereof, will be settled by final and binding
arbitration to be conducted in Boston, Massachusetts pursuant to the national
rules for the resolution of employment disputes of the American Arbitration
Association then in effect. The decision or award in any such arbitration will
be final and binding upon the parties, and judgment upon such decision or award
may be entered in any court of competent jurisdiction, or application may be
made to any such court for judicial acceptance of such decision or award and an
order of enforcement. In the event that any procedural matter is not covered by
the aforesaid rules, the procedural law of Massachusetts will govern. Any
disagreement as to whether
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 11 of 16

a particular dispute is arbitrable under this Agreement shall itself be subject
to arbitration in accordance with the procedures set forth herein.

12.   No Oral Modification, Cancellation or Discharge; Seal. This Agreement may
be amended or terminated only in writing signed by you and the Company. This
Agreement shall operate in all respects as an instrument under seal.

13.   Governing Law; Jurisdiction and Venue. This Agreement will be governed by
the laws of the Commonwealth of Massachusetts, without giving effect to the
conflict of law principles thereof. Any legal action or proceeding with respect
to this Agreement that is not subject to arbitration pursuant to Section 11 will
be brought in the courts of the Commonwealth of Massachusetts or of the United
States of America for the District of Massachusetts. By execution and delivery
of this Agreement, each of the parties hereto accepts for itself and in respect
of its property, generally and unconditionally, the exclusive jurisdiction of
the aforesaid courts.

14.   Acknowledgment. You acknowledge that you have had the opportunity to
discuss this matter with and obtain advice from your private attorney, have had
sufficient time to, and have carefully read and fully understand all the
provisions of this Agreement, and are knowingly and voluntarily entering into
this Agreement.

15.   Severability. The parties intend this Agreement to be enforced as written.
However, (a) if any portion or provision of this Agreement is to any extent
declared illegal or unenforceable by a duly authorized court having
jurisdiction, then the remainder of this Agreement, or the application of such
portion or provision in circumstances other than those as to which it is so
declared illegal or unenforceable, will not be affected thereby, and each
portion and provision of this Agreement will be valid and enforceable to the
fullest extent permitted by law, and (b) if any provision, or part thereof, is
held to be unenforceable because of the duration of such provision, the
geographic area covered thereby, or other aspect or scope of such provision, the
court making such determination will have the power to reduce the duration or
geographic area of such provision, or other aspect or scope of such provision,
and/or to delete specific words and phrases ("blue-penciling"), and in its
reduced or blue-penciled form, such provision will then be enforceable and will
be enforced.

16.   Counterparts. This Agreement may be executed in two or more counterparts,
and by different parties hereto on separate counterparts, each of which will be
deemed an original, but all of which together will constitute one and the same
instrument.
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 12 of 16

By signing below, you acknowledge and agree to the foregoing understandings and
agreements set forth herein.

                                    ALTUS PHARMACEUTICALS INC.

                                          By:  /s/ John Richard
                                               ----------------------------
                                               John Richard
                                               Chairman of the Board Member

ACKNOWLEDGED AND AGREED:

/s/ Sheldon Berkle      May 10, 2005
-------------------     ------------
Sheldon Berkle          Date
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 13 of 16

                                  EXHIBIT 3(d)

                                PRIOR INVENTIONS
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 14 of 16

                                   APPENDIX B

Altus offers a medical and dental plan which includes coverage of most
prescription drugs, annual physicals, young well-child care and vaccinations,
women's health checkups, vision care, dental coverage, and other features. Altus
requires a 15% premium co-payment to be applied to health insurance costs, but
this co-payment is capped at a maximum of 1% of gross salary. We may advise you
to undergo a baseline medical surveillance exam, at our expense, for purposes of
occupational health screening. We offer Altus-paid life insurance in an amount
equal to approximately twice your base salary, as well as an industry-standard
disability insurance program. We also have a 401(k) tax-deferred savings plan.
This is a voluntary plan which you will be eligible for after your first full
calendar quarter of employment. The plan is administered at our expense,
allowing you to save a portion of your income in a tax-deferred manner. Employee
savings through the 401(k) plan are matched by a Company contribution in the
form of cash, currently on the basis of $0.75 of cash for every $1.00 saved by
the employee, up to the first 6% of salary, subject to certain limits required
by law.
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 15 of 16

                                   APPENDIX C

For purposes of this letter agreement, "CAUSE" shall include (and is not limited
to) (i) dishonesty with respect to the Company or any Affiliate (an "Affiliate"
being any corporation which, for purposes of Section 424 of the Internal Revenue
Code, is a parent or subsidiary of the Company, direct or indirect), (ii)
insubordination, (iii) substantial malfeasance or nonfeasance of duty, (iv)
unauthorized disclosure of confidential information, (v) breach by you of any
material provision of any employment, consulting, advisory, nondisclosure,
non-competition or similar material agreement between you and the Company, which
breach is not cured to the satisfaction of the Board of Directors within ten
(10) days after notice to you by the Company of such breach, and (vi) conduct
substantially prejudicial to the business of the Company or any Affiliate. The
determination of the Board of Directors (unless it has delegated power to act on
its behalf to a committee, in which case the determination of the committee) as
to the existence of "cause" will be conclusive on you and the Company.

For purposes of this letter agreement, "CHANGE IN CONTROL" shall mean:

                        (i) the shareholders of the Company approve (a) any
consolidation or merger of the Company (x) where the shareholders of the
Company, immediately prior to the consolidation or merger, would not,
immediately after the consolidation or merger, beneficially own, directly or
indirectly, shares representing in the aggregate more than 50% of the combined
voting power of all the outstanding securities of the corporation issuing cash
or securities in the consolidation or merger (or of its ultimate parent
corporation, if any) or (y) where the members of the Board of Directors of the
Company, immediately prior to the consolidation or merger, would not,
immediately after the consolidation or merger, constitute more than 50% of the
board of directors of the corporation issuing cash or securities in the
consolidation or merger (or of its ultimate parent corporation, if any), (b) any
sale, lease, exchange or other transfer (in one transaction or a series of
transactions contemplated or arranged by any party as a single plan) of all or
substantially all of the assets of the Company, or (c) any plan or proposal for
the liquidation or dissolution of the Company.

                        (ii) individuals who, as of the date hereof, constitute
the entire Board of Directors of the Company (the "Incumbent Directors") cease
for any reason to constitute at least 50% of the Board, provided that any
individual becoming a director subsequent to the date hereof whose election, or
nomination for election by the Company's shareholders, was approved by a vote of
at least a majority of the then Incumbent Directors shall be, for purposes
hereof, considered as though such individual were an Incumbent Director; or
<PAGE>
Mr. Sheldon Berkle
May 6, 2005
Page 16 of 16

                        (iii) any "person", as such term is used in Section
13(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act")
(other than the Company, any employee benefit plan of the Company or any entity
organized, appointed or established by the Company for or pursuant to the terms
of such plan), together with all "affiliates" and "associates" (as such terms
are defined in Rule 12b-2 under the Exchange Act) of such person, shall after
the date hereof become the "beneficial owner" or "beneficial owners" (as defined
in Rules 13d-3 and 13d-5 under the Exchange Act), directly or indirectly, of
securities of the Company representing in the aggregate 25% or more of either
(a) the then outstanding shares of the Common Stock of the Company or (b) the
combined voting power of all then outstanding securities of the Company having
the right under ordinary circumstances to vote in an election of the Board of
Directors of the Company ("Voting Securities") (in either such case, other than
as a result of acquisitions of such securities directly from the Company).

            Notwithstanding the foregoing, a "change in control" of the Company
shall not be deemed to have occurred for purposes of the foregoing clause (iii)
solely as the result of an acquisition of securities by the Company which, by
reducing the number of shares of Common Stock or other Voting Securities
outstanding, increases (a) the proportionate number of shares of Common Stock
beneficially owned by any person to 25% or more of the Common Stock then
outstanding or (b) the proportionate voting power represented by the Voting
Securities beneficially owned by any person to 25% or more of the combined
voting power of all then outstanding Voting Securities; provided, however, that
if any person referred to in clause (a) or (b) of this sentence shall thereafter
become the beneficial owner of any additional shares of Common Stock or other
Voting Securities (other than pursuant to a stock split, stock dividend or
similar transaction), then a "change in control" shall be deemed to have
occurred for purposes of the foregoing clause (iii).

For purposes of this letter agreement, resigning for "GOOD REASON" means you
terminate your employment after there has occurred (i) a material adverse change
in your duties, authority or responsibilities which causes your position with
the Company to become of significantly less responsibility or authority than it
was immediately prior to such change, or (ii) a reduction in your base salary or
(ii) a material diminution in the overall package of employee benefits as
described in Appendix B to the Offer Letter dated May 6, 2005, which change does
not also apply to other executive employees of the Company.
<PAGE>

                               September 29, 2005

Mr. Sheldon Berkle
450 Terracina Lane
Naples, FL 34119

Dear Shelly:

         The purpose of this letter agreement (this "Agreement") is to amend
that certain letter agreement between you and Altus Pharmaceuticals Inc. (the
"Company") dated May 6, 2005 (the "Offer Letter"), in order to convert the loan
set forth in the fourth paragraph thereof into a stay bonus in order to comply
with the provisions of Section 402 of the Sarbanes-Oxley Act of 2002.
Capitalized terms used but not defined herein shall have the meanings ascribed
to them in the Offer Letter.

         In consideration of your continued service to the Company as the
President, Chief Executive Officer and a member of the Board of Directors, and
the promises, conditions and representations set forth herein, and other good
and valuable consideration, the receipt and sufficiency of which is hereby
acknowledged by you and the Company, you and the Company hereby agree that the
Offer Letter is amended as follows:

         1. AGREED AMENDMENT. In consideration of the termination of the
$150,000 loan made to you by the Company on the Commencement Date, you are
hereby granted a bonus of $153,500 (the "Bonus") as of the date hereof. Such
Bonus shall be paid to you as follows: (a) $150,000 of the Bonus shall be paid
to you by means of your retention of the amount of the aforementioned loan,
which the Company hereby forgives, and (b) $3,500 shall be paid to you by means
of an additional payment from the Company. The Bonus will be fully taxable to
you upon payment. Should you voluntarily terminate your employment or the
Company terminates your employment for cause (as defined in the Offer Letter)
before the first anniversary of the Commencement Date, you shall repay to the
Company within ninety (90) days of such termination an amount equal to $150,000
less the amount of taxes incurred by you in connection with your receipt of such
portion of the Bonus. Should you voluntarily terminate your employment or the
Company terminates your employment for cause after the first anniversary and
before the second anniversary of the Commencement Date, you shall repay to the
Company within ninety (90) days of such termination an amount equal to $75,000
less the amount of taxes incurred by you in connection with your receipt of such
portion of the Bonus. If you remain in the continuous employment of the Company
between the Commencement Date and the second anniversary of the Commencement
Date, any obligation to repay the Bonus or a portion thereof shall lapse in its
entirety. Please note that if you resign for good reason (as defined in the
Offer Letter), it will not be considered a voluntary termination by you of your
employment, and you will have no repayment obligation. You will also have no
repayment obligation if your employment is terminated by Altus, except if such
termination is for cause.

<PAGE>

Mr. Sheldon Berkle
September 29, 2005
Page 2

         2. GOVERNING LAW. This Agreement shall be deemed to have been made in
Massachusetts, shall take effect as an instrument under seal within
Massachusetts, and shall be governed by and construed in accordance with the
laws of Massachusetts, without giving effect to conflict of law principles.

         3. EFFECT ON ORIGINAL AGREEMENT. Except as specifically provided in
this Agreement, no other amendments, revisions or changes are made to the Offer
Letter. All other terms and provisions of the Offer Letter shall remain in full
force and effect.

         4. COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

         By executing this Agreement, you are acknowledging that you have been
afforded sufficient time to understand, and seek advice from your personal
counsel, on the terms and effects of this Agreement, and that your agreements
hereunder are made voluntarily, knowingly and without duress, and that neither
the Company nor its agents or representatives have made any representations
inconsistent with the provisions of this Agreement.

                                  Sincerely,

                                  ALTUS PHARMACEUTICALS INC.

                                  By:  /s/ John Richard
                                      ---------------------------
                                      John Richard
                                      Chairman of the Board

CONFIRMED, ACKNOWLEDGED AND AGREED:

/s/ Sheldon Berkle
-----------------------------
Sheldon Berkle

Dated: September 29, 2005<PAGE>

                                                                   EXHIBIT 10.26

                               PURCHASE AGREEMENT

      Agreement made as of the 10 day of October, 2005 (the "Agreement Date"),
between Altus Pharmaceuticals Inc., a Delaware corporation with its principal
office at 125 Sidney Street, Cambridge, MA 01239, USA ("ALTUS"), and Sandoz
GmbH, a company organized under the laws of Austria with its principal office at
Biochemiestrasse 10, Kundl, AUSTRIA ("SANDOZ").

      WHEREAS, ALTUS desires to purchase, and SANDOZ desires to sell, certain
quantities of human growth hormone ("HGH"), for the consideration set forth
below, subject to the terms and conditions of this Agreement;

      WHEREAS, ALTUS desires to use the HGH in its research and development
program for ALTU-238, including preclinical and clinical activities, which may
take place both inside and outside the United States; and

      WHEREAS, ALTUS and SANDOZ anticipate [***] between the parties regarding
the [***] [***] with respect to HGH.

      NOW, THEREFORE, in consideration of the mutual promises hereinafter set
forth and other good and valuable consideration, the receipt and sufficiency of
which is hereby acknowledged, the parties hereby agree as follows:

      1. Sale and Delivery of HGH

            1.1 Orders. Upon SANDOZ's receipt of a purchase order (an "Order")
from ALTUS submitted in accordance with the terms set forth on Exhibit B, SANDOZ
shall sell, based on EXW (INCOTERM 2000) - Kundl plant to ALTUS such quantities
of HGH specified in each such Order. Unless otherwise agreed to by the parties,
the aggregate amount of HGH covered by all Order(s) shall not [***] of [***] HGH
and [***] [***] [***]HGH, except as stated in Exhibit B. ALTUS shall have right
to submit Orders based on conditions as set forth in Exhibit B to this contract.

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

            1.2 Supply of HGH. SANDOZ shall fill each Order submitted by ALTUS
after ALTUS' submission of the Order in accordance with Exhibit B. [***] SANDOZ
shall include with each [***] shipment a Certificate of Analysis confirming that
such shipment conforms to the specifications set forth on Exhibit A. The [***]
shipments will be chosen from SANDOZ Batch [***] (Exhibit C) or Batch [***]
(Exhibit D). The HGH shall be frozen and packaged for shipment in appropriate
amounts of dry ice and supplied by SANDOZ ex works Kundl plant for delivery to
ALTUS. Shipment shall be arranged by SANDOZ utilizing a commercial carrier
approved by ALTUS. All packages shall contain a data logger to monitor package
disposition during shipping, and such information shall be accessible by both
parties.

            1.3 Purchase Price. The purchase price (the "Purchase Price") for
HGH shall be as follows: [***] HGH purchased by ALTUS hereunder shall be [***]
per gram and [***]HGH purchased by ALTUS hereunder shall be [***] per gram.

            Upon ALTUS having purchased [***] [***] [***] [***] HGH hereunder
according to Exhibit B, SANDOZ shall supply [***] [***] [***] HGH [***] in
accordance with Exhibit B. Upon ALTUS having purchased [***] [***] [***] HGH
hereunder according to Exhibit B, SANDOZ shall supply [***] [***] in accordance
with Exhibit B.

            The Purchase Price for each shipment of HGH delivered under ALTUS'
Orders shall be payable at [***] after acceptance of an individual Order by
Sandoz 30 days prior to scheduled delivery and at [***] within 30 days of the
invoice date, being understood that invoicing will be done upon shipment of the
material; provided, however, that if ALTUS reasonably determines that any [***]
HGH delivered by SANDOZ does not conform to the specifications set forth in
Exhibit A or was not prepared under cGMP, and notifies SANDOZ of such
non-conformity within 30 days after receipt and provides supporting
documentation, (i) SANDOZ shall immediately replace at SANDOZ' expense the
non-conforming [***] HGH with conforming [***] HGH, (ii) the cost of shipping
and any other costs associated with the supply of the replacement [***] HGH will
be borne by [***] and (iii) ALTUS shall not be obligated to pay for the shipment
of non-conforming HGH but shall be obligated to pay for the

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

replacement HGH within 30 days from the date of its receipt thereof. If ALTUS
reasonably determines that any [***] HGH delivered by SANDOZ does not conform to
the specifications set forth in Exhibit C or D, as appropriate, and notifies
SANDOZ of such non-conformity within 30 days after receipt and provides
supporting documentation, Altus shall be entitled to a refund of any invoices
paid.

      2. Covenants by SANDOZ. SANDOZ hereby covenants that:

            2.1 Prior to December 31, 2005, SANDOZ will provide ALTUS with a
written authorization (a Letter of Authorization) to reference [***]has
previously filed or files with the U.S. Food and Drug Administration ("FDA")
with respect to their HGH product. In the event that ALTUS decides to conduct a
clinical trial in a non-U.S. jurisdiction, ALTUS shall notify SANDOZ of the
information required for regulatory purposes regarding the HGH. It is likely
such information will include at least information comparable to and present in
a US FDA Drug Master File. SANDOZ shall provide such information to the extent
existing in Sandoz and access to such information where filed with regulatory
authorities via a Letter of Authorisation to the appropriate regulatory
authorities as soon as reasonably practicable after receiving notice of ALTUS'
intent to conduct such trial. ALTUS shall reimburse SANDOZ for the reasonable
costs incurred in providing such assistance in accordance with Section 4.3.

            2.2 SANDOZ agrees to allow ALTUS to inspect SANDOZ' hGH
manufacturing facility [***] per year and limited to [***] days and to cooperate
with requests from the FDA and other regulatory authorities relating to the HGH
sold to ALTUS hereunder. The parties shall mutually agree in good faith on the
appropriate scope and timing of any audit or audits initiated by ALTUS. Only
ALTUS employees shall conduct such audit(s) unless SANDOZ consents to the use of
a specific consultant or consultant(s) identified by ALTUS, such consent not to
be unreasonably withheld or conditioned.

            2.3 SANDOZ shall keep ALTUS informed of any warning letters relating
to the manufacture of HGH received from any national regulatory authorities
(e.g. US, EU, Australian) and shall keep ALTUS informed of any responses
thereto.

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

      3. Representations and Warranties

            3.1 Ownership of the HGH. SANDOZ warrants that with respect to any
HGH supplied to ALTUS hereunder, SANDOZ is the true and lawful owner of such
HGH, and has the right to sell and transfer to ALTUS good and clear title to the
HGH.

            3.2 Conformance With Specifications and Regulatory Requirements. The
[***] HGH supplied hereunder shall (i) conform to the specifications set forth
in Exhibit A and any Certificate of Analysis which accompanies such shipment
through the product expiration date for such shipment, which expiration date
shall not be earlier than [***] HGH manufactured and shipped under this Purchase
Agreement, (ii) shall have been manufactured in accordance with Current Good
Manufacturing Practices as defined in Title 21 Code of Federal Regulations Parts
210 and 211, and in compliance with all applicable laws, rules and regulations,
and (iii) conform to the product characteristics and manufacturing procedures
set forth in the DMF. The [***] HGH supplied hereunder shall conform to the
Exhibit C or D Certificate of Analyses, as appropriate.

SANDOZ warrants that the HGH delivered hereunder will not be adulterated or
misbranded within the meaning set forth in Federal Food, Drug, and Cosmetic Act
(FDCA) or any state or local law or regulation substantially similar to FDCA.
SANDOZ further warrants that any [***] HGH supplied hereunder will conform to
the specifications set forth in Exhibit A upon release by SANDOZ.

            3.3 No Clinical Hold. SANDOZ represents that as of the date of this
Agreement, there is no clinical hold in the United States or the EU based on the
suitability of the HGH for human use.

            3.4 No Implied Warranties. EXCEPT FOR THE WARRANTIES IN 3.1 AND 3.2
SANDOZ DISCLAIMS ALL WARRANTIES, WHETHER EXPRESS OR IMPLIED, WITH RESPECT TO THE
HGH PROVIDED HEREUNDER, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE.

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

      4. Covenants by ALTUS. ALTUS here by covenants that:

            4.1 The [***] HGH covered by this Agreement will only be used in
ALTUS' [***], which activities may take place inside or outside of the United
States. The [***] HGH covered by this Agreement will only be used in ALTUS'
[***] activities, which activities may take place inside or outside of the
United States.

            4.2 The HGH will not be resold.

            4.3 ALTUS agrees to reimburse SANDOZ for the reasonable time spent
by SANDOZ personnel in handling FDA requests relating exclusively to ALTUS' use
of the HGH sold to ALTUS hereunder and/or in assisting an inspection conducted
by ALTUS pursuant to Section 2.2, such assistance to be reimbursed at a rate of
[***] per man-hour; provided, however, upon request, SANDOZ shall provide ALTUS
with a good faith estimate of the number of man-hours required to accommodate
ALTUS' requests in advance of any such inspection. VAT shall be added if
required by law.

      5. Indemnification; Limitation of Liability.

            5.1 ALTUS shall indemnify SANDOZ and hold SANDOZ harmless from and
against any and all liability for death, illness or injury to any third party or
for loss or damage to any third party's property and against all claims,
demands, proceedings and causes of action resulting directly or indirectly
therefrom and arising out of any act or default on the part of ALTUS, its
employees, agents or sub-contractors in the performance of or in compliance with
any of their obligations under this Agreement, including without limitation any
and all loss in relation to defective HGH including any liability arising under
any relevant product liability legislation which may apply from time to time due
to defective HGH, except to the extent any such loss or damage is caused by a
breach of SANDOZ's representations or warranties to ALTUS hereunder.

            5.2 SANDOZ shall indemnify ALTUS and hold ALTUS harmless from and
against any and all loss or liability for claims, demands, proceedings and
causes of

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

action arising from, relating to or caused by a breach of SANDOZ's
representations or warranties to ALTUS in 3.1 and 3.2 hereunder.

            5.3 In no event shall either party in any circumstances be liable to
the other for any consequential or indirect loss or damage or loss of profit of
whatsoever nature, including damage to goodwill, loss of market share, existing
or prospective.

      6. Confidentiality. Each party shall during the term of this Agreement and
for 5 years thereafter keep strictly confidential information disclosed by the
other party under this Agreement, not disclose the information to any third
party without the prior written consent of the other party and exclusively use
such information for no other purpose than its performance under this Agreement;
however, the above provisions shall not apply to any information which falls
into any of the following exceptions:

      (a) information already in the public domain at the time of disclosure;

      (b) information which has become part of the public domain due to reasons
other than the fault of receiving party;

      (c) information already in the possession of receiving party at the time
of disclosure, which fact the receiving party shall prove by documentary
evidence;

      (d) information disclosed to the receiving party by a third party
authorized to do so; or

      (e) information whose disclosure to the appropriate governmental
authorities is necessary in connection with the performance of the parties'
obligations and rights under this Agreement, including, without limitation,
disclosure in connection with the clinical development and regulatory approval
of products developed by ALTUS.

      7. Term; Termination. This Agreement shall take effect as of the date
first above written and shall remain in effect until December 31, 2006, or such
later date as shall be mutually agreed upon by the parties. Either party may
terminate this Agreement upon written notice in the event the other party shall
have breached this Agreement and failed to cure such breach within 30 days of
receipt of written notice

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

thereof. Notwithstanding any termination or expiration of this Agreement,
neither party shall be relieved of any obligations incurred prior to such
termination or expiration and the obligations of the parties with respect to
confidentiality, indemnification and any other provision which by its nature is
intended to survive any such termination or expiration, shall survive and
continue to be enforceable.

      8. Notices. Any notices or other communications required or permitted
hereunder shall be sufficiently given if delivered personally or sent by telex,
federal express, registered or certified mail, postage prepaid, addressed as
follows or to such other address of which the parties may have given notice:

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

To SANDOZ:

                Sandoz GmbH
                Biochemiestrasse 10
                A- 6250 Kundl
                AUSTRIA
                Telecopier No.:
                Attn:  Head Biotech Cooperations

To ALTUS:

                Altus Pharmaceuticals Inc.
                125 Sidney Street
                Cambridge, MA 01239
                USA
                Telecopier No.:  001-617-299-2999
                Attn: President

Unless otherwise specified herein, such notices or other communications shall be
deemed received (a) on the date delivered, if delivered personally; or (b) three
business days after being sent, if sent by registered or certified mail.

      9. Successors and Assigns. This Agreement shall be binding upon and inure
to the benefit of the parties hereto and their respective successors and
permitted assigns.

      10. Entire Agreement. This Agreement, and all Exhibits hereto, represent
the entire understanding and agreement between the parties hereto with respect
to the subject matter hereof and supersede all prior oral and written and all
contemporaneous oral negotiations, commitments and understandings between such
parties.

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

      11. Expenses. Except as otherwise expressly provided herein, ALTUS and
SANDOZ shall each pay their own expenses in connection with this Agreement and
the transactions contemplated hereby.

      12. Governing Law; Arbitration. This Agreement shall be governed by and
construed in accordance with the laws of the state of New York, USA. Any dispute
hereunder shall be resolved through binding arbitration under the rules of the
International Chamber of Commerce in Paris. Any such arbitration shall be held
in Zurich/Switzerland in the English language. The arbitrator(s) shall also
allocate the cost of such proceedings including reasonable attorneys' fees.

      13. Section Headings. The section headings are for the convenience of the
parties and in no way alter, modify, amend, limit, or restrict the contractual
obligations of the parties.

      14. Severability. The invalidity or unenforceability of any provision of
this Agreement shall not affect the validity or enforceability of any other
provision of this Agreement.

      15. Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original, but all of which
shall be one and the same document.

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

      IN WITNESS WHEREOF, this Agreement has been duly executed by the parties
hereto as of and on the date first above written.

ALTUS PHARMACEUTICALS INC.                   SANDOZ GMBH

By:_________________________                 By:________________________

Name:_______________________                 Name:______________________

Title:______________________                 Title:_____________________

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

                                    Exhibit A

               HUMAN GROWTH HORMONE DRUG SUBSTANCE SPECIFICATIONS

The specifications for the HGH to be supplied by SANDOZ under this Agreement are
as follows:

<TABLE>
<CAPTION>
       TEST                                                            ANALYTICAL PROCEDURE                     ACCEPTANCE CRITERIA
       ----                                                            --------------------                     -------------------
<S>                                                                    <C>                                      <C>
1.     DESCRIPTION

1.1.   Appearance                                                      Visual inspection                        [***]

1.2.   pH                                                              Potentiometry                            [***]

1.3.   Clarity                                                         Ph. Eur.                                 [***]

2.     IDENTITY OF EP2000

2.1.   Primary structure                                               Peptide map by RP-HPLC                   [***]

2.2.   Hydrophobicity                                                  Reversed phase chromatography            [***]

2.3.   Isoelectric point                                               Isoelectric focusing                     [***]

2.4.   Molecular size                                                  Size exclusion chromatography            [***]

2.5.   Molecular size                                                  SDS-PAGE                                 [***]

3.     PURITY

3.1.   Product related substances and impurities by RP-HPLC            Reversed phase chromatography (RP-HPLC)  [***]

3.1.1  Product related substances (deamidated, succinimide, oxidized)  Reversed phase chromatography (RP-HPLC)  [***]

3.1.2  Product related impurities (clipped and other variants)         Reversed phase chromatography (RP-HPLC)  [***]

3.1.3. Product related substances and impurity by CZE                  Capillary zone electrophoresis           [***]

3.2.   High molecular weight proteins                                  Size exclusion chromatography            [***]

3.3.   Charge isoforms                                                 Isoelectric focusing                     [***]

3.4.   High and low molecular weight                                   SDS-PAGE                                 [***]
</TABLE>

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

<TABLE>
<S>                                                                    <C>                                      <C>
       proteins

3.5.   Residual acetonitrile                                           Headspace GC                             [***]

3.6.   E. coli host cell proteins                                      Immuno ligand assay (ILA)                [***]

3.7.   Residual DNA                                                    Threshold method                         [***]

3.8.   Bioburden                                                       Microbial limit test filtration method
                                                                       Specify microorganism if found           [***]

3.9.   Bacterial endotoxins                                            LAL, kinetic chromogenic                 [***]

3.10.  Residual urea                                                   Enzymatic determination with urease      [***]

4.     CONTENT

4.1.   Assay                                                           Size exclusion chromatography            [***]

4.3.   Phosphate                                                       Photometry                               [***]
</TABLE>

--------
* To be provided to ALTUS prior to or upon shipment

Storage and transport conditions: < or = -20 degrees C

The HGH shall have been manufactured in accordance with current good
manufacturing practices ("cGMP") for pharmaceuticals as described in applicable
regulations promulgated by the U.S. Food and Drug Administrative, including
those set forth in 21 CFR Parts 210 and 211.

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

                                    Exhibit B

                       Order Schedule and Shipping Details

1. No order will be considered placed and no HGH will be shipped without ALTUS
submitting an Order for the HGH.

2. SANDOZ shall have no obligation to fill Orders for [***] HGH scheduled for
delivery in [***] unless ALTUS has placed such Order(s) prior to [***]. It is
currently anticipated that Orders for cGMP HGH will be placed to meet the
following delivery schedule:

      -     [***] [***]

3. Additional [***] HGH may be purchased by ALTUS [***] with the submission of
an Order. SANDOZ will fill these orders as Sandoz may have commercial quantities
of HGH available for sale to third parties up to a maximum of [***] g.

4. Orders for [***] HGH will be placed by ALTUS by [***] the latest to meet the
following delivery schedule:

      -     [***]

      Unless otherwise specified in an Order, all HGH shall be shipped to:

Altus Pharmaceuticals Inc.
Attn: Sujit Basu, PhD.
625 Putnam Ave.
Cambridge, MA  02139
USA

2. SANDOZ shall ship such HGH corresponding to above mentioned delivery schedule
after ALTUS' submission of the corresponding Order. The purchase order will
contain instructions as to where the [***] HGH is to be shipped and how the
shipment is to be labeled.

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

                                    Exhibit C

                                      [***]

                                      [***]

[SANDOZ LOGO]

                              CERTIFICATE OF ANALYSIS       Order No.

                                                            Material No. 454994

                                                            KNGL

Product
[***]
Batch                         Manufacture date              Expiry date
[***]                         [***]                         [***]

<TABLE>
<CAPTION>
               Tests                   Specifications           Results
               -----                   --------------           -------
<S>                           <C>                           <C>
[***]                         [***]                         [***]
[***]                         [***]                         [***]
[***]                         [***]                         [***]
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                              [***]
</TABLE>

The manufacturing records have been reviewed, the batch was manufactured [***]

We certify that the above mentioned product conforms with the
specifications:                                                        PAGE 1/1

[***]

                                  SANDOZ GmbH
DATE OF RELEASE [***]         A-6250 KUNDL/AUSTRIA               Rejected

                                                            Dr. Brigitte Latal

KUNDL,                                                 SANDOZ QUALITY ASSURANCE

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

<PAGE>

                                    Exhibit D

                                      [***]

                                      [***]

[SANDOZ LOGO]

                              CERTIFICATE OF ANALYSIS       Order No.

                                                            Material No. 454994

                                                            KNGL

Product
[***]
Batch                         Manufacture date              Expiry date
[***]                         [***]                         [***]

<TABLE>
<CAPTION>
              Tests                   Specifications             Results
              -----                   --------------             -------
<S>                           <C>                           <C>
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                              [***]
</TABLE>

The manufacturing records have been reviewed, the batch was manufactured [***]

We certify that the above mentioned product conforms with the
specifications:                                                        PAGE 1/1

[***]
                                  SANDOZ GmbH
DATE OF RELEASE [***]         A-6250 KUNDL/AUSTRIA            Rejected

                                                          Dr. Brigitte Latal

KUNDL,                                                 SANDOZ QUALITY ASSURANCE

PORTIONS OF THIS EXHIBIT WERE OMITTED AND HAVE BEEN FILED SEPARATELY WITH THE
SECRETARY OF THE COMMISSION PURSUANT TO THE COMPANY'S APPLICATION REQUESTING
CONFIDENTIAL TREATMENT UNDER RULE 406 OF THE SECURITIES ACT.

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00095-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00095-of-00352.parquet"}]]