Adaptimmune Therapeutics plc Proposes Public Offering of American Depositary Shares PHILADELPHIA, Pa. and OXFORD, UK., January 21 , 2020 - Adaptimmune Therapeutics plc (Nasdaq: ADAP), a leader in T-cell therapy to treat

Adaptimmune Therapeutics plc Proposes

Public Offering of American Depositary Shares

Pa. and OXFORD, UK., January 21, 2020 - Adaptimmune

Therapeutics plc (Nasdaq: ADAP), a leader in T-cell therapy to treat cancer, today announced that it intends to offer and sell

American Depositary Shares ("ADSs") in an underwritten public offering. The offering is subject to market conditions,

and there can be no assurance as to whether or when the offering may be completed, or as to the actual size or terms of the offering.

Adaptimmune also expects to grant the underwriters a 30-day option to purchase additional ADSs at the public offering price. All

of the ADSs in the offering are to be sold by Adaptimmune, with net proceeds to be used to advance the development of Adaptimmune's

immunotherapies into and through clinical trials as well as for other general corporate purposes.

Cowen is acting as sole book-running manager for the offering.

A shelf registration statement on Form S-3 relating to the public

offering of the ADSs described above was declared effective by the Securities and Exchange Commission ("SEC") on September

10, 2019. The offering is being made only by means of a written prospectus and prospectus supplement that form a part of the registration

statement. A preliminary prospectus supplement relating to and describing the terms of the offering will be filed with the SEC

and will be available on the SEC's web site at www.sec.gov. When available, copies of the preliminary prospectus supplement

relating to these securities may also be obtained by sending a request to: Cowen and Company, LLC, c/o Broadridge Financial Solutions,

1155 Long Island Avenue, Edgewood, NY, 11717, Attn: Prospectus Department, by email at PostSaleManualRequests@broadridge.com or

by telephone at (833) 297-2926.

This press release does not constitute an offer to sell or the

solicitation of an offer to buy any of these securities, nor will there be any sale of these securities in any state or other jurisdiction

in which such offer, solicitation or sale is not permitted.

For readers in the European Economic Area

In any EEA Member State, this communication is only addressed

to and directed at qualified investors in that Member State within the meaning of the Prospectus Regulation. The term "Prospectus

Regulation" means Regulation (EU) 2017/1129.

For readers in the United Kingdom

This communication, in so far as it constitutes an invitation

or inducement to enter into investment activity (within the meaning of s21 Financial Services and Markets Act 2000 as amended)

in connection with the securities which are the subject of the offering described in this press release or otherwise, is being

directed only at (i) persons who are outside the United Kingdom or (ii) persons who have professional experience in matters relating

to investments who fall within Article 19(5) (Investment professionals) of the Financial Services and Markets Act 2000 (Financial

Promotion) Order 2005 (the "Order") or (iii) certain high value persons and entities who fall within Article 49(2)(a)

to (d) (High net worth companies, unincorporated associations etc) of the Order; or (iv) any other person to whom it may lawfully

be communicated (all such persons in (i) to (iv) together being referred to as "relevant persons"). The ADSs are only

available to, and any invitation, offer or agreement to subscribe, purchase or otherwise acquire such ADSs will be engaged in only

with, relevant persons. Any person who is not a relevant person should not act or rely on this communication or any of its contents.

Adaptimmune is a clinical-stage biopharmaceutical company focused

on the development of novel cancer immunotherapy products for people with cancer. The Company's unique SPEAR (Specific

Peptide Enhanced Affinity Receptor) T-cell platform enables the engineering of T-cells to target and destroy cancer across multiple

Forward-Looking Statements

This release contains "forward-looking statements"

within the meaning of the Private Securities Litigation Reform Act of 1995 (PSLRA). These forward-looking statements involve certain

risks and uncertainties. Such risks and uncertainties could cause our actual results to differ materially from those indicated

by such forward-looking statements, and include, without limitation: the success, cost and timing of our product development activities

and clinical trials and our ability to successfully advance our TCR therapeutic candidates through the regulatory and commercialization

processes. For a further description of the risks and uncertainties that could cause our actual results to differ materially from

those expressed in these forward-looking statements, as well as risks relating to our business in general, we refer you to our

Quarterly Report on Form 10-Q filed with the SEC on November 6, 2019, and our other SEC filings. The forward-looking statements

contained in this press release speak only as of the date the statements were made and we do not undertake any obligation to update

such forward-looking statements to reflect subsequent events or circumstances.

Adaptimmune Contacts:

S bastien Desprez - VP, Communications and Investor

Juli P. Miller, Ph.D. - Senior Director, Investor Relations