April 17, 2025

Hugh S. Griffith
Chief Executive Officer
NuCana plc
3 Lochside Way
Edinburgh, EH12 9DT
United Kingdom

        Re: NuCana plc
            Draft Registration Statement on Form F-1
            Submitted April 4, 2025
            CIK No. 0001709626
Dear Hugh S. Griffith:

       We have conducted a limited review of your draft registration statement
and have the
following comments.

        Please respond to this letter by providing any requested information
and by publicly
filing your registration statement and non-public draft submission on EDGAR. If
you do not
believe a comment applies 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 this letter
and your filed
registration statement, we may have additional comments.

Draft Registration Statement on Form F-1
Cover Page

1.     We note your disclosure on page 10 that the Series A Warrants and Series
B Warrants
       contain reset provisions that may result in a downward adjustment to the
exercise
       price of such warrants, and that may result in a corresponding increase
to the number
       of ADSs issuable upon the exercise of such warrants, and that,
additionally, if the
       Series B Warrants are exercised by way of an "alternative cashless
exercise," such
       exercising holder will receive three ADSs for each ADS they would
receive in a cash
       exercise for the Series B Warrants they exercise, without any cash
payment to the
       company (subject to the mandatory nominal exercise price). Please revise
the cover
       page headings, the cover page narrative and the Prospectus Summary to
highlight the
       maximum number of ADSs that could be issued upon the exercise of your
Series A
 April 17, 2025
Page 2

       Warrants and Series B Warrants, and, if similar formulas apply, the
Pre-Funded
       Warrants. For guidance, refer to Regulation S-K Item 501(b)(2).
Additionally, as
       appropriate for each of the respective warrants, disclose that the
number of ADSs
       issuable upon the exercise of such warrants increases as the stock price
falls further
       below the initial exercise price of such warrants.
2.     With respect to the "alternative cashless exercise" feature of the
Series B Warrants,
       please revise the cover page narrative and Prospectus Summary to
explain, if true, that
       as a result of this feature you do not expect to receive any cash
proceeds from the
       exercise of those warrants because it is highly unlikely that a warrant
holder would
       wish to pay an exercise price to receive one ADS when they could choose
the
       "alternative cashless exercise" option and pay no money, except for the
mandatory
       nominal exercise price, to receive three ADSs. Additionally, please
include in your
       disclosure, where appropriate, the value of the "mandatory nominal
exercise price"
       referenced on page 10.
Risk Factors
Risks Related to This Offering
We are selling a substantial number of ADSs in this offering, which could cause
the price of
our ADSs to decline., page 9

3.     We note your risk factor disclosure on page 10 that the Series A
Warrants and the
       Series B Warrants contain exercise price adjustments, adjustments to
increase the
       number of ADSs "issuable" upon exercise, and, in the case of the Series
B Warrants,
       an "alternative cashless exercise" feature, which, if triggered, may
cause substantial
       dilution. Please revise the risk factor disclosure, or add a new risk
factor, to address
       potential dilution from the reset provisions that could adjust upward
the number of
       ADSs underlying the Series A Warrants and the Series B Warrants and from
the
       "alternative cashless exercise" feature of the Series B Warrants. The
risk factor should
       disclose the maximum number of ADSs that may be issuable upon exercise
of all of
       the Warrants.
4.     Please include a risk factor stating, if true, that this offering could
cause the price of
       your ADSs to fall below the minimum bid price required by the Nasdaq
Listing Rules,
       which could result in your ADSs being delisted from Nasdaq. To the
extent you have
       plans to seek shareholder approval for a reverse stock split or have
plans to increase
       the number of ordinary shares represented by your ADSs, please disclose
such plans
       in this registration statement, including the proposed ratio, if known.
General

5.     We note your references in your prospectus to an "alternative cashless
exercise" of the
       Series B Warrants. The term "cashless exercise" is generally understood
to allow a
       warrant holder to exercise a warrant without paying cash for the
exercise price and
       reducing the number of shares receivable by the holder by an amount
equal in value to
       the aggregate exercise price the holder would otherwise pay to exercise
the warrants.
       In cashless exercises, it is expected that the warrant holder receives
fewer shares than
       they would if they opted to pay the exercise price in cash. Please
clarify your
       disclosure throughout the prospectus by removing the references to
"alternative
 April 17, 2025
Page 3

       cashless exercise" and exclusively using the term "zero exercise price"
or another
       appropriate term that conveys that, in addition to the company receiving
no, or
       nominal, cash upon the "alternative cashless exercise," the warrant
holders would be
       entitled to receive more ADSs than they would under the cash exercise
terms.
        We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence
of action by the staff.

       We also remind you that your registration statement must be on file at
least two
business days prior to the requested effective date and time. Refer to Rules
460 and 461
regarding requests for acceleration. Please allow adequate time for us to
review any
amendment prior to the requested effective date of the registration statement.

       Please contact Joshua Gorsky at 202-551-7836 or Tim Buchmiller at
202-551-3635
with any other questions.



                                                            Sincerely,

                                                            Division of
Corporation Finance
                                                            Office of Life
Sciences
cc:   John T. Rudy, Esq.