Company: NCNA
Filing Date: 2025-06-27
Form Type: 424B5
Source: 0001193125-25-151464
Chunk: 21

Company: NuCana plc
Filing Date: 2025-06-27
Form: 424B5
Chunk 21
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 is qualified in all respects by that reference. Copies of all or any part of the registration statement, including the documents incorporated by reference or the exhibits, are available to you on the SEC’s website at http://www.sec.gov, as listed above in “Where You Can Find More Information.” The documents we are incorporating by reference are:

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We are also incorporating by reference all subsequent Annual Reports on Form 20-F that we file with the SEC and certain reports on Form 6-K that we furnish to the SEC after the date of this prospectus supplement (if they state that they are
incorporated by reference into this prospectus supplement) prior to the termination of this offering. In all cases, you should rely on the later information over different information included in this prospectus supplement or any accompanying
prospectus.

Unless expressly incorporated by reference, nothing in this prospectus supplement shall be deemed to incorporate by reference
information furnished to, but not filed with, the SEC. Copies of all documents incorporated by reference in this prospectus supplement, other than exhibits to those documents unless such exhibits are specifically incorporated by reference in this
prospectus supplement, will be provided at no cost to each person, including any beneficial owner, who receives a copy of this prospectus supplement on the written or oral request of that person made to:

NuCana plc

3 Lochside Way

Edinburgh, EH12 9DT

United Kingdom

Telephone: +44 (0)131 357 1111

You may also access these documents on our website, www.nucana.com. The information contained on, or that can be accessed through, our website
is not a part of this prospectus supplement. We have included our website address in this prospectus supplement solely as an inactive textual reference.

You should rely only on information contained in, or incorporated by reference into, this prospectus supplement. We have not authorized anyone
to provide you with information different from that contained in this prospectus supplement or incorporated by reference in this prospectus supplement. We are not making offers to sell the securities in any jurisdiction in which such an offer or
solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make such offer or solicitation.

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PROSPECTUS

$150,000,000

American Depositary Shares representing Ordinary Shares

Debt Securities

Warrants

Rights

Units

This prospect