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United States securities and exchange commission logo
June 20, 2021
Ren Russo, Pharm.D.
President and Chief Executive Officer
Xilio Therapeutics, Inc.
828 Winter Street
Waltham, Massachusetts 02451
Re: Xilio Therapeutics,
Inc.
Draft Registration
Statement on Form S-1
Submitted May 24,
2021
CIK No. 0001840233
Dear Dr. Russo:
We have reviewed your draft registration statement and have the
following comments. In
some of our comments, we may ask you to provide us with information so
we may better
understand your disclosure.
Please respond to this letter by providing the requested
information and either submitting
an amended draft registration statement or publicly filing your
registration statement on
EDGAR. If you do not believe our comments apply to your facts and
circumstances or do not
believe an amendment is appropriate, please tell us why in your
response.
After reviewing the information you provide in response to these
comments and your
amended draft registration statement or filed registration statement, we
may have additional
comments.
Draft Registration Statement on Form S-1
Our Pipeline, page 4
1. Please include the
indication for each program in the pipeline table here and on page 117.
Overview, page 4
2. We note your disclosure
that cytokines have demonstrated the ability to generate sustained
complete responses. If
this disclosure is based on the data in the chart presented on page
112, please balance
your disclosure to indicate, if true, that only a small subset of patients
who received high-dose
IL-2 achieved a complete response, or tell us the basis for this
disclosure. Please also
disclose the nature of the compelling clinical efficacy
demonstrated by
cytokines in certain tumors.
Ren Russo, Pharm.D.
Xilio Therapeutics, Inc.
June 20, 2021
Page 2
Our GPS Platform, page 6
3. We note your disclosure that your engineered molecules are designed to
be turned on
selectively in the TME, thereby reducing potential toxicities and
improving their
therapeutic index. We note, however, that some of your statements in
this section and
elsewhere indicate less activity outside of the TME and some
statements indicate no
activity. For example, we note your disclosure in this section that
MMPs are
preferentially active in the TME by comparison to non-tumor
organs or tissues, and that
your GPS-enabled cytokines minimize or reduce the risk of activity
outside of the TME
and, therefore, the risk of toxicity. Given those disclosures, please
tell us why your
disclosure in this section that MMP activity can be leveraged to
activate molecules within
the TME that "remain inactive outside of the TME", and that the
features of your GPS-
enabled molecules work in concert to enable your molecules
potential ability to induce
tumor selective biological activity and tumor growth inhibition
"without toxicity outside
of the TME," are appropriate, or revise your disclosure as necessary.
Our History and Team, page 7
4. We note that you identify certain entities as investors in your
company here and on page
107. However, certain of these entities do not appear to be among your
principal
stockholders as disclosed on page 186. If material, please expand your
disclosure to
describe the nature of each such entity's investment in you and
explain to us why
including this information is appropriate. Please also explain in the
response your plans to
update investors about any changes these entities make with respect to
their investments in
your company.
Our Strategy, page 8
5. We note your disclosure here and throughout the prospectus comparing
XTX202
to aldesleukin, and XTX101 to an ipilimumab analog. Please clarify, if
true, that these
observations were made in mouse models and may not be replicated in
clinical trials.
Risk Factors, page 16
6. Given the length of your risk factor section, please revise to comply
with Regulation S-K
Item 105 by relocating risks that could generically apply to any
registrant or offering to
the end of the section under the caption "General Risk Factors."
Some intellectual property that we have in-licensed may have been discovered
through
government funded programs,
FirstName LastNameRen pagePharm.D.
Russo, 52
Comapany
7. NameXilio
Please revise to Therapeutics, Inc. candidates that are or may be
subject to march-
identify the product
in2021
June 20, rights.
Page 2
FirstName LastName
Ren Russo, Pharm.D.
FirstName LastNameRen
Xilio Therapeutics, Inc. Russo, Pharm.D.
Comapany
June NameXilio Therapeutics, Inc.
20, 2021
June 20,
Page 3 2021 Page 3
FirstName LastName
Capitalization, page 82
8. Please revise to reflect the convertible preferred stock outside of
permanent equity
consistent with your interim balance sheet on page F-40.
Dilution, page 84
9. Please revise your disclosure to clarify that historical net tangible
book value (deficit)
excludes convertible preferred stock classified outside of equity.
Management's Discussion and Analysis of Financial Condition and Results of
Operations
Critical Accounting Policies and Use of Estimates
Determination of Fair Value of Common Units and Common Stock, page 104
10. Please disclose the actual specific factors underlying the increase in
the May 2021
common stock valuation to $1.06.
Business
Key Features of Our GPS-Enabled Cytokines, page 114
11. We note your disclosure on pages 115 and 116 that you have validated
your GPS platform
through your preclinical studies with XTX202 and by your
tumor-selective anti-CTLA-4
antibody. Please revise to explain what you mean by validated given
the current stage of
development of your product candidates.
Cytokine programs, page 117
12. We note your disclosure on page 27 that you rely on matrix
metalloproteases to activate
your molecules within the tumor microenvironment and that if MMP
activity in human
tumors is not sufficient to cleave the masking protein domain, the
potential efficacy of
your product candidates would be limited. For each of your cytokine
programs, please
clarify whether you have observed that the MMPs native to human cells
are sufficient to
cleave the masking domain.
Measured PK Parameters (1 mg/kg dose), page 123
13. We note your statement that you expect XTX202 to achieve monotherapy
activity in
clinical trials and have a better tolerability profile than
aldesleukin based on your
preclinical data. Given the unpredictability of drug development,
please remove this
statement and any similar statements as such statements would appear
to be speculative.
Principal Stockholders, page 186
14. Please revise your disclosure to identify all of the natural person or
persons who have
voting and investment control of the shares held by the entities
affiliated with Atlas
Ventures, F-Prime Capital Partners Healthcare Fund IV LP and
affiliates, Takeda
Ventures, Inc. and SV7 Impact Medicine Fund LP.
Ren Russo, Pharm.D.
Xilio Therapeutics, Inc.
June 20, 2021
Page 4
General
15. Please supplementally provide us with copies of all written
communications, as defined in
Rule 405 under the Securities Act, that you, or anyone authorized to do
so on your behalf,
present to potential investors in reliance on Section 5(d) of the
Securities Act, whether or
not they retain copies of the communications.
You may contact Michael Fay at (202) 551-3812 or Vanessa Robertson at
(202) 551-
3649 if you have questions regarding comments on the financial statements and
related matters.
Please contact Ada Sarmento at (202) 551-3798 or Tim Buchmiller at (202)
551-3635 with any
other questions.
Sincerely,
FirstName LastNameRen Russo, Pharm.D.
Division of
Corporation Finance
Comapany NameXilio Therapeutics, Inc.
Office of Life
Sciences
June 20, 2021 Page 4
cc: Cynthia T. Mazareas, Esq.
FirstName LastName