Achilles Therapeutics Announces Pricing of Initial Public Offering

Achilles Therapeutics plc (NASDAQ: ACHL), a clinical-stage biopharmaceutical company developing precision T cell therapies to treat solid tumors, today announced the pricing of its initial public offering in the United States of 9,750,000 American Depositary Shares (“ADSs”) representing 9,750,000 ordinary shares at an initial public offering price of $18.00 per ADS for total gross proceeds of $175.5 million. All ADSs sold in the offering are being offered by Achilles. The ADSs are expected to begin trading on The Nasdaq Global Select Market on March 31, 2021 under the ticker symbol “ACHL.”  In addition, Achilles has granted the underwriters a 30-day option to purchase up to an additional 1,462,500 ADSs at the initial public offering price, less underwriting discounts and commissions. The offering is expected to close on April 6, 2021, subject to customary closing conditions.

J.P. Morgan, BofA Securities and Piper Sandler are acting as joint book-running managers for the offering. Chardan, Oppenheimer & Co, and Kempen & Co are acting as co-managers.

A registration statement relating to these securities was declared effective on March 30, 2021. The securities referred to in this announcement are to be offered only by means of a prospectus. A copy of the final prospectus, when available, may be obtained from:

• J.P. Morgan Securities LLC, Attention Equity Syndicate Desk, 383 Madison Avenue, New York, New York 10179, or via email: [e-mail];
• BofA Securities, Attention: Prospectus Department, NC1-004-03-43, 200 North College Street, 3rd Floor, Charlotte, NC 28255-0001, or via email: [e-mail]; or
• Piper Sandler & Co., Attention: Prospectus Department, 800 Nicollet Mall, J12S03, Minneapolis, MN 55402, by telephone: [phone], or via email: [e-mail].

About Achilles Therapeutics

Achilles is a clinical-stage, biopharmaceutical company developing precision T cell therapies targeting clonal neoantigens: protein markers unique to the individual that are expressed on the surface of every cancer cell. Achilles has two ongoing Phase I/IIa trials, the CHIRON trial in patients with advanced non-small cell lung cancer (NSCLC) and the THETIS trial in patients with recurrent or metastatic melanoma. Achilles uses DNA sequencing data from each patient, together with its proprietary PELEUS™ bioinformatics platform, to identify clonal neoantigens specific to that patient, and then develop precision T cell-based product candidates specifically targeting those clonal neoantigens.

Lee M. Stern – VP, IR & External Communications+1 (332) [e-mail]

Consilium Strategic CommunicationsMary-Jane Elliott, Sukaina Virji, Melissa Gardiner+44 (0) 203 709 [e-mail]