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Mail Stop 6010

								November 15, 2005


Sheldon Berkle
President and Chief Executive Officer
Altus Pharmaceuticals Inc.
125 Sidney Street
Cambridge, MA 02139

	Re:	Altus Pharmaceuticals Inc.
		Registration Statement on Form S-1
		Filed October 17, 2005
		File No. 333-129037

Dear Mr. Berkle:

	We have reviewed your filing and have the following comments.
Where indicated, we think you should revise your document in
response
to these comments.  If you disagree, we will consider your
explanation
as to why our comment is inapplicable or a revision is
unnecessary.
Please be as detailed as necessary in your explanation.  In some
of
our comments, we may ask you to provide us with information so we
may
better understand your disclosure.  After reviewing this
information,
we may raise additional comments.

	Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your filing.
We
look forward to working with you in these respects.  We welcome
any
questions you may have about our comments or any other aspect of
our
review.  Feel free to call us at the telephone numbers listed at
the
end of this letter.

FORM S-1

General

1. Please provide us proofs of all graphic, visual, or
photographic
information you will provide in the printed prospectus prior to
its
use, for example in a preliminary prospectus.  Please note we may
have
comments regarding these materials.

2. Please note that when you file a pre-effective amendment
containing
pricing-related information, we may have additional comments.  As
you
are likely aware, you must file this amendment prior to
circulating
the prospectus.

3. Please note that when you file a pre-effective amendment that
includes your price range, it must be bona fide.  We interpret
this to
mean your range may not exceed $2 if you price below $20 and 10%
if
you price above $20.

4. We have received your application for confidential treatment of
certain exhibits.  We will send our comments on the confidential
treatment application under separate cover.  These comments will
need
to be resolved prior to effectiveness.

Prospectus Summary, page 1

5. Your Summary is much longer and more detailed than is
anticipated
by Item 503(a) of Regulation S-K.  We also note that much of the
information in the Summary is repeated verbatim in the Business
section of your document.  Please revise to provide a
substantially
shorter Summary.  For example, any discussion of your product
candidates in the Summary should be limited to the product`s name,
a
brief description of what it does or is designed to do, and its
development status.  This information is currently included in the
"Our Company" discussion, so the "Our Product Candidates" and "Our
Product Pipeline" discussions do not appear to be necessary for
the
Summary.  We may have further comments on your Summary section
after
seeing your revisions.

6. Please revise the "Risks Associated with Our Business" to
quantify
your losses in each of the past three fiscal years.  Similarly
revise
the risk factor titled "We have a history of net losses, which we
expect to continue for at least the next several years and, as a
result, we are unable to predict the extent of any future losses
or
when, if ever, we will achieve, or be able to maintain,
profitability."

Risk Factors

7. If any participants in clinical trials have experienced
material
adverse effects, please revise to include a separate risk factor
describing these adverse effects.

If we fail to obtain the additional capital . . . , page 8

8. We note you expect that the proceeds from this offering, your
existing cash resources and investment securities, and payments
you
expect to receive from your collaborators will be sufficient to
support your operations through the first half of 2007.  Please
explain the assumptions on which you have based this projection.
For
example:
* does the projection assume you will make any of the payments to
CFFTI prior to the first half of 2007;
* what clinical trials or preclinical trials does this assumption
assume you will have performed; and
* does this projection assume you have received milestone
payments?
If so, how much does it assume you have earned in milestone
payments?

9. Please include as a separate risk factor the discussion of the
amounts you will be obligated to pay CFFTI if you obtain FDA
approval.

We may not be successful in maintaining our existing
collaborations .
. . , page 10

10. Please discuss the dispute with Dr. Falk in a separate risk
factor.  The risk factor should identify the country in which the
third-party patent is held.  It should also discuss how this claim
could affect ALTU-135 in that country, the other countries covered
by
the agreement with Dr. Falk, and worldwide.

If clinical trials for our product candidates are prolonged . . .
,
page 13

11. If any of the items in the bullet points have actually
occurred
and materially affected your business in the past, please discuss
the
situation.

If we do not obtain required regulatory approvals . . . , page 13

12. This risk factor is similar to "If we are unable to
commercialize
. . ." on page 11 and "Because our product candidates are in
early- or
mi-stage development . . ." on pages 12-13.  Please consolidate it
into one or both of these risk factors and remove any repetitive
text.

Our product candidates will remain subject to ongoing regulatory .
. .
, page 15

13. Please explain what "untitled letters" are.

Our development of ALTU-238 could be significantly delayed . . . ,
page 14

14. We note you may use a supplier with an approved NDA for its
hGH
product, in which case you will seek a right of reference to the
safety and efficacy data underlying the supplier`s NDA.  Please
clarify what the supplier would provide.  For example, would the
supplier provide only an ingredient, or would it provide an
approved
drug that you will somehow modify?  If it will provide an approved
drug, please explain what you will do to the drug that will
necessitate further FDA approval.  We may have further comments.

15. We note the FDA has informed you that the FDA has not approved
any
hGH product under section 505(b)(2).  Does this mean there
currently
does not exist a supplier with an approved NDA from which you
could
obtain a right of reference?  If so, please make that fact clearer
at
the beginning of the risk factor.  Also, please clarify the
section
under which your competitors identified at the bottom of page 9
received approval for their hGH products.

16. Please briefly explain what section 505(b)(1) and section
505(b)(2) of the FDCA say.

Failure to obtain regulatory approvals . . . , page 14

17. If you believe your business is dependent on obtaining
approval in
any specific countries, please identify those countries.

We deal with hazardous materials and must comply . . . , page 16

18. We note you are subject to environmental laws and regulations.
Please provide the information required by Item 101(c)(xii) of
Regulation S-K in your Business section.

19. Please disclose the limitations on your insurance coverage.
Similarly revise the risk factor titled "There is a substantial
risk
of product liability claims in our business.  If we are unable to
obtain sufficient insurance, a product liability claim against us
could adversely affect our business."

Risks Related to Our Dependence on Third Parties, page 16

20. If your business or product development efforts have been
materially harmed due to a third party`s failure to perform,
please
discuss the situation in one of the risk factors in this section.

We currently rely on a single manufacturer . . . , page 17

21. We note you rely on Amano Enzymes for the manufacture of ALTU-
135.
Please identify the manufacturer of ALTU-238, and disclose in this
risk factor that you do not have a written agreement with this
party.

22. Please update this risk factor during the course of our review
if
you learn whether Amano will be your primary manufacturer.


If third parties successfully assert that we have infringed . . .
,
page 21

23. To the extent you are aware that you have any intellectual
property that is being infringed upon or that you have been
notified
of a third party`s belief that you are infringing on their
intellectual property, please revise to disclose the situation and
potential consequences.

24. Please state which party has the obligation to enforce patent
patents under your material license or collaboration agreements.
If
your company does not have the obligation, state whether it has
the
right.

A significant portion of our total outstanding shares are
restricted .
. . , page 26

25. Please state how many shares are currently restricted from
resale
and when the restrictions expire.

Investors in this offering will pay . . . , page 27

26. Please revise this risk factor to explain that investors who
purchase shares will contribute ___% of the total amount to fund
the
company but will own only ___% of the voting rights.

Use of Proceeds, page 29

27. Please disclose approximately how much funds you plan to use
for
the items described in each of the bullet points.

Management`s Discussion and Analysis of Financial Condition and
Results of Operations

Financial Operations Overview, page 36

Research and Development Expense, page 37

28. We note that you include a discussion of the estimated costs
to
complete ALTU-135, but not any of the other significant projects
such
as ALTU-238.  We also note that you include costs by project for
the
most recent two years presented.  To further enhance your
disclosures
please provide the following:

* The costs incurred during each period presented, including FY
2002
and to date, on the project;
* The nature, timing and estimated costs of the efforts necessary
to
complete the project;
* The anticipated completion dates;
* The risks and uncertainties associated with completing
development
on schedule, and the consequences to operations, financial
position
and liquidity if the project is not completed timely; and finally
* The period in which material net cash inflows from significant
projects are expected to commence.

Regarding the second and third bullet points, disclose the amount
or
range of estimated costs and timing to complete the phase in
process
and each future phase. To the extent that information is not
estimable, disclose those facts and circumstances indicating the
uncertainties that preclude you from making a reasonable estimate.

Critical Accounting Policies and Significant Judgments and
Estimates,
page 39

Revenue, page 39

29. We note that your discussion of the impact that these costs
estimates seems to be limited to the CFFTI revenues, and not any
of
the other revenues.  Please expand your discussion to include the
impact that all changes in estimates had for the periods
presented.
Also provide a sensitivity analysis to help understand the impact
that
changes in these estimates may have on future operations.

Stock-Based Compensation, page 40

30. Your disclosure here and elsewhere in the filing, refers to an
independent appraisal.  The reference to an independent valuation
firm
equates to the use of a valuation expert.  Please name the
independent
appraiser and provide the consent of the appraiser in the
registration
statement.

Business, page 49

31. Please provide your basis for the following statements:

* hGH disorders in both pediatric and adult populations generated
approximately $2.2 billion in worldwide sales of hGH in 2004 and
the
market grew at a compound annual growth rate of approximately 15%
from
2002 to 2004 (page 50); and
* We estimate that chronic pancreatitis results in more than
500,000
physician visits per year in the United States (page 53).

If your estimates are based on independent third party
documentation,
please provide this documentation.  Please note, such materials
should
be marked to indicate the information used in making your
estimates.

Overview, page 49

32. Please explain the basis for your belief that some
manufacturers
of existing pancreatic enzyme replacement products may not be able
to
meet the April 28, 2008 deadline for obtaining FDA approval.

33. Please disclose what it means to have the orphan drug and fast
track designations.

34. We note from the second full paragraph on page 50 that you
apply
your technology to existing, well-understood proteins with well-
defined mechanisms of action.  Please revise to clarify what your
product development entails.  For example, do the drugs already
exist,
and your technology crystallizes them so they are usable?  Also,
clarify how your products differ from existing protein therapies.

Our Strategy, page 50

35. We note the reference to a phase II/III clinical trial for
ALTU-
238.  In order to use the term II/III, we require that the study
meet
the requirements of both phase II and phase III.  Please confirm
that
the phase II/III clinical trial in pediatric patients is expected
to
meet the requirements of both phase II and phase III.  Otherwise,
revise to eliminate the reference to phase II/III.  If you retain
the
reference to phase II/III and there is a possibility that you may
need
to perform an additional trial after the phase II/III trial,
please
disclose this possibility.

Our Product Candidates, page 51

36. Since it appears you plan to market your products throughout
the
world, please discuss the products` development status in
countries
other than the United States.

ALTU-135 Development Activities and Strategy, page 55

37. Since you discuss the results of your phase II trials on ALTU-
135,
please disclose what statistical analysis was performed and the
degree
of statistical significance found as measured by the p-values
obtained.  In doing so, you should define any technical terms you
use.

Dr. Falk Pharma GmbH, page 62

38. We note the license with Dr. Falk continues in each country
until
the expiration of the last-to-expire patent in the country or a
specified term from the date of first commercial sale in that
country.
Please state when the last-to-expire patent is scheduled to expire
in
each of the principal countries covered by the agreement.  Also,
state
the "specified term" applicable to each of these countries.

39. We note that Dr. Falk has agreed to pay a portion of the
development expenses in connection with an international Phase III
clinical trial.  Please revise to quantify the portion he has
agreed
to pay.

Management, page 77

40. Please disclose Dr. Navia`s business experience since March
2003.
Also, disclose Dr. Klibanov`s business experience for the past
five
years.  If he has been a professor for the past five years, make
that
fact clear by stating the date he became a professor.

Principal Stockholders, page 92

41. For each shareholder in the principal stockholders table that
is
neither a natural person nor a public reporting company, please
revise
to identify the natural person with voting and investment control.
Also, identify the natural persons in addition to Jonathan D. Root
who
beneficially own the shares held by Entities affiliated with U.S.
Venture Partners.

Underwriting, page 103

42. Please tell us whether you intend to include a directed share
offering as part of your public offering.  If so, provide
appropriate
disclosure in the Underwriting section.  Advise us as to the
procedures you will follow and how your directed share offering
will
be in compliance with Section 5 of the Securities Act of 1933 and
Rule
134 of the Act.  Also provide us with all material you will
provide to
the participants in the directed share offering prior to its use.
We
may have further comments.

Electronic Distribution, page 105

43. We note the underwriters will post an electronic prospectus on
their website, and they might allocate shares for sale to their
online
brokerage account holders.  Please tell us the procedures they
will
use in their selling efforts and how they intend to comply with
the
requirements of Section 5 of the Securities Act of 1933,
particularly
with regard to how offers and final confirmations will be made and
how
and when purchasers will fund their purchases.  Provide us copies
of
all electronic communications including the proposed web pages.

44. Please tell us and briefly disclose in the prospectus whether
you
intend to use any forms of prospectus other than print and the
electronic prospectus already discussed, such as CD-ROMs, videos,
etc., and provide all such prospectuses for our examination.
Please
refer to SEC Releases No. 33-7233 and No. 33-7289.  We may have
additional comments.

Financial Statements, page F-1

Consolidated Statements of Operations, page F-4

45. Please revise you presentation to include a pro forma EPS that
reflects the conversion of the preferred shares for the most
recent
fiscal year and interim period.

2.  Summary of Significant Accounting Policies, page F-8

Intangible Assets, page F-9

46. Please explain to us your basis for capitalizing the warrants
issued to CFFTI in connection with this arrangement.  Include a
discussion of what this intangible asset represents under the
guidance
of SFAS 142.  Include any other references to the specific
paragraphs
within the authoritative literature that support this treatment.

Revenue Recognition, page F-9

47. We note that you use the percentage of completion method to
record
revenues associated with the various research and development
agreements.  We also note that the applicability of SOP 81-1
excludes
service contracts such as this one.  Please explain to us why you
feel
that this accounting is appropriate.  Please note that the
instances
where we accept similar treatment are generally allowed based on
the
ability of a company to use an output measure instead of an input
measure such as costs to support the revenue earned to date under
these agreements.

9.  Commitments and Contingencies, page F-15

Commitment to CFFTI, page F-15

48. Please explain to us how you arrived at the accounting for
this
potential obligation to repay the funding provided by CFFTI.
Include
a discussion of what obligations you have with respect to
continuing
this project and the implications that terminating this project
has on
your potential obligation to repay this amount.  Include any
references to the applicable authoritative literature upon which
you
relied in arriving at this treatment.

14.  Stock Options, page F-21

49. Please provide us with an analysis of how you determined the
fair
value of the underlying common stock and any related stock-based
compensation for each equity and redeemable convertible preferred
issuance.  Please include an itemized chronological schedule
covering
all equity instruments issued, including options, warrants and
preferred stock, since December 31, 2003 through the date of your
response.  Please provide the following information separately for
each equity and convertible preferred issuance or grant:

a. Date of each issuance or transaction;
b. Number of shares granted, issued or issuable;
c. Purchase price or exercise price per share;
d. Any restrictions or vesting terms;
e. Management`s fair value per share estimate;
f. The significant factors, assumptions and methodologies
management
used in determining fair value;
g. Identity of the recipient, indicating if the recipient was a
related party;
h. The nature of any concurrent transactions with the recipient;
i. Significant factors contributing to the difference between fair
value as of the date of each grant and fair value as of the date
of
your response;
j. How the grant or issuance was treated for purposes of computing
earnings per share; and
k. The valuation alternative selected and, if appropriate, the
reason
management chose not to obtain a contemporaneous valuation by an
unrelated valuation specialist.

Highlight transactions with unrelated parties, if any, that
management
believes to be particularly evident of an objective fair market
value
per share determination.  Progressively bridge management`s fair
value
per share determinations to the current estimated IPO price per
share.
Include when the company began discussions with the underwriter.
Please note that, because the initial filing did not include an
estimated offering price, we are deferring evaluation of common
stock
related compensation until you specify the estimated offering
price.

Item 16. Exhibits and Financial Statement Schedules, page II-4

50. We note some of your exhibits are not yet filed.  Please be
aware
that we may have comments on the exhibits after they are filed,
and
any comments will need to be resolved prior to effectiveness.

51. It does not appear you have discussed the material terms of
exhibits 10.8-10.12 in the body of your filing.  Please revise to
include such a discussion in "Liquidity and Capital Resources."

*	*	*

	As appropriate, please amend your registration statement in
response to these comments.  You may wish to provide us with
marked
copies of the amendment to expedite our review.  Please furnish a
cover letter with your amendment that keys your responses to our
comments and provides any requested information.  Detailed cover
letters greatly facilitate our review.  Please understand that we
may
have additional comments after reviewing your amendment and
responses
to our comments.

	We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filing to be certain that the
filing
includes all information required under the Securities Act of 1933
and
that they have provided all information investors require for an
informed investment decision.  Since the company and its
management
are in possession of all facts relating to a company`s disclosure,
they are responsible for the accuracy and adequacy of the
disclosures
they have made.

	Notwithstanding our comments, in the event the company
requests
acceleration of the effective date of the pending registration
statement, it should furnish a letter, at the time of such
request,
acknowledging that:

* should the Commission or the staff, acting pursuant to delegated
authority, declare the filing effective, it does not foreclose the
Commission from taking any action with respect to the filing;

* the action of the Commission or the staff, acting pursuant to
delegated authority, in declaring the filing effective, does not
relieve the company from its full responsibility for the adequacy
and
accuracy of the disclosure in the filing; and

* the company may not assert staff comments and the declaration of
effectiveness as a defense in any proceeding initiated by the
Commission or any person under the federal securities laws of the
United States.

	In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division
of Corporation Finance in connection with our review of your
filing or
in response to our comments on your filing.

	We will consider a written request for acceleration of the
effective date of the registration statement as confirmation of
the
fact that those requesting acceleration are aware of their
respective
responsibilities under the Securities Act of 1933 and the
Securities
Exchange Act of 1934 as they relate to the proposed public
offering of
the securities specified in the above registration statement.  We
will
act on the request and, pursuant to delegated authority, grant
acceleration of the effective date.

	We direct your attention to Rules 460 and 461 regarding
requesting acceleration of a registration statement.  Please allow
adequate time after the filing of any amendment for further review
before submitting a request for acceleration.  Please provide this
request at least two business days in advance of the requested
effective date.

	You may contact James Peklenk at (202) 551-3661 or James
Atkinson
at (202) 551-3674 if you have questions regarding comments on the
financial statements and related matters.  Please contact Greg
Belliston at (202) 551-3861 or me at (202) 551-3715 with any other
questions.

								Sincerely,



								Jeffrey Riedler
								Assistant Director

cc:	Jonathan L. Kravetz, Esq.
	Megan N. Gates, Esq.
	Scott A. Samuels, Esq.
	Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
	One Financial Center
	Boston, MA 02111
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Sheldon Berkle
Altus Pharmaceuticals Inc.
November 15, 2005
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