United States securities and exchange commission logo

                          December 23, 2020

       Iraj Ali, Ph.D.
       Chief Executive Officer
       Achilles Therapeutics plc
       245 Hammersmith Road
       London W6 8PW
       United Kingdom

                                                        Re: Achilles
Therapeutics plc
                                                            Draft Registration
Statement on Form F-1
                                                            Submitted November
27, 2020
                                                            CIK No. 0001830749

       Dear Dr. Ali:

              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

             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

       Draft Registration Statement on Form F-1

       Overview, page 1

   1.                                                   It appears you have
developed PELEUS as a platform to accumulate bioinformatic data to
                                                        identify clonal
neoantigens, and VELOS as a manufacturing process to create cNeT
                                                        therapies. Please
explain your Material Acquisition Platform and how it differs from
 Iraj Ali, Ph.D.
FirstName   LastNameIraj
Achilles Therapeutics  plcAli, Ph.D.
December    NameAchilles
                2020       Therapeutics plc
Page  2     23, 2020 Page 2
FirstName LastName
Our cNeT approach, page 3

2.       In the graphic on page 3 please include the total amount of time
required between
         extracting blood and tumor samples from the patient to when your
products can be
         reinfused into the patient for treatment.
Our pipeline, page 5

3.       We note that your pipeline table includes preclinical programs for
TNBC and bladder
         cancer. As your narrative disclosure only briefly discusses these
programs and you have
         not allocated any proceeds for their development in your use of
proceeds section, please
         explain to us why you believe these programs are sufficiently material
to your business to
         be included in a pipeline table.

4.       Please state whether larger Phase IIb clinical trials will be required
prior to commencing
         Phase III clinical trials and if so, please revise your table to
clarify that there will be
         multiple Phase II trials.
Use of proceeds, page 106

5.       Please revise your disclosure in this section to disclose the cNeT
programs to which you
         intend to allocate proceeds from the offering. Please disclose how far
the proceeds from
         the offering will allow you to advance your programs for the treatment
of advanced
         NSCLC and metastatic or recurrent melanoma. In addition, please
specify the amounts
         you intend to allocate to each of the PELEUS platform and to the VELOS
License agreements, page 120

6.       Please expand your discussion to quantify the value of the 1,568,420 B
ordinary shares
         and 268,420 C ordinary shares that were issued to CRT upon execution
of the license
7.       Please expand your disclosure to describe the LOHHLA patent in greater
detail and how it
         is used in your business. We note that the additional sample period
that was extended in
         the most recent amendment has now expired. Please tell us the impacts
of this expiration
         has on your business.
Management   s Discussion and Analysis of Financial Condition and Results of
Determination of the fair value of the ordinary shares , page 132

8.       Once you have an estimated offering price or range, please explain to
us how you
         determined the fair value of the common stock underlying your equity
issuances and the
         reasons for any differences between the recent valuations of your
common stock leading
         up to the IPO and the estimated offering price. This information will
help facilitate our
         review of your accounting for equity issuances including stock
compensation. Please
 Iraj Ali, Ph.D.
Achilles Therapeutics plc
December 23, 2020
Page 3
         discuss with the staff how to submit your response.
Overview, page 137

9.       Please expand your discussion of MAP to clarify your stage of
development of this
         platform. For example, we note you intend to use proceeds from the
offering to further
         the development of HNSCC and RCC but it does not appear that you
intend to use
         proceeds to further develop MAP. Is this platform fully developed?
Our Programs, page 151

10.      We note the disclosure on page 25 regarding the ongoing the THETIS
trial patient who
         experienced immune effector cell-associated neurotoxicity syndrome,
which was deemed
         possibly related to ATL001. Please expand the discussion here to
discuss all serious
         adverse events related, or possibly related, to treatment. Please
include the nature of each
         such event and the number of patients that experienced it.
Our current manufacturing and expansion plans, page 155

11.      Please disclose the material terms of your agreement with Cell Therapy
Employees, page 178

12.      Please revise to describe any specific measures or objectives that
management focuses on
         in managing the business, such as measures or objectives that address
the development,
         attraction and retention of personnel. Refer to Item 101(c)(2)(ii) of
Regulation S-K and
         SEC Release No. 33-10825.

13.    Please supplementally provide us with copies of all written
communications, as defined in
FirstName LastNameIraj Ali, Ph.D.
       Rule 405 under the Securities Act, that you or anyone authorized to do
so on your behalf,
Comapany    NameAchilles
       present to potential Therapeutics  plc
                            investors in reliance on Section 5(d) of the
Securities Act, whether or
       not they
December        retainPage
           23, 2020    copies
                           3 of the communications.
FirstName LastName
 Iraj Ali, Ph.D.
FirstName   LastNameIraj
Achilles Therapeutics  plcAli, Ph.D.
December    NameAchilles
                2020       Therapeutics plc
Page  4     23, 2020 Page 4
FirstName LastName
       You may contact Julie Sherman at 202-551-3640 or Kevin Kuhar at
202-551-3662 if you
have questions regarding comments on the financial statements and related
matters. Please
contact Chris Edwards at 202-551-6761 or Suzanne Hayes at 202-551-3675 with any


                                                        Division of Corporation
                                                        Office of Life Sciences
cc:      Seo Salimi