Third Patient Treated with HG-CT-1 CAR-T Therapy

15 August 2025

Hemogenyx Pharmaceuticals plc

("Hemogenyx Pharmaceuticals" or the "Company")

Third Patient Treated with HG-CT-1 CAR-T Therapy and Completion of First Adult Dose Cohort

Hemogenyx Pharmaceuticals plc (LSE: HEMO) is pleased to announce that the third patient has been successfully treated as part of the Company's ongoing Phase I clinical trial of HG-CT-1, its proprietary CAR-T cell therapy for relapsed or refractory acute myeloid leukemia ("R/R AML") in adults.

Treatment of this patient, the final participant in the first adult dose cohort, was made possible after the Company secured special permission from the U.S. Food and Drug Administration (FDA) to proceed under exceptional circumstances. This regulatory clearance reflects the Company's ability to navigate complex clinical challenges to ensure eligible patients can access potentially life-saving therapies.

Completion of the first adult dose cohort, which received the lowest dose of HG-CT-1, represents a pivotal milestone in the Company's trial. If no dose-limiting toxicities are observed, Hemogenyx Pharmaceuticals will:

·      Advance to the second adult dose cohort at twice the initial dose, and

·      Initiate recruitment for the pediatric arm of the trial, addressing a critical unmet need in childhood AML.

The Phase I trial is a dose-escalation study designed to assess safety and collect data on key secondary endpoints, including anti-leukemic activity, overall survival, progression-free survival, and duration of response. The Company is pleased to report that the first two patients treated with HG-CT-1 remain alive at six months and three months post-treatment, respectively.

Dr. Vladislav Sandler, CEO & Co-Founder of Hemogenyx Pharmaceuticals, commented:

"Completing the first adult dose cohort is a major achievement in our Phase I trial of HG-CT-1. I am proud of our team's persistence in working with the FDA to obtain the necessary clearance to treat this patient. With this milestone reached, we are well positioned to move into the higher-dose cohort and to open our pediatric arm, advancing our mission to deliver transformative therapies for AML patients of all ages."

Market Abuse Regulation (MAR) Disclosure

Certain information contained in this announcement would have been inside information for the purposes of Article 7 of Regulation No 596/2014 (as it forms part of UK domestic law by virtue of the European Union (Withdrawal) Act 2018) until the release of this announcement. The person responsible for arranging for the release of this announcement on behalf of Hemogenyx Pharmaceuticals plc is Dr Vladislav Sandler, Chief Executive Officer & Co-Founder.

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About Hemogenyx Pharmaceuticals plc

Hemogenyx Pharmaceuticals is a publicly traded company (LSE: HEMO) headquartered in London, with its US operating subsidiaries, Hemogenyx Pharmaceuticals LLC and Immugenyx LLC, located in New York City.

The Company is a clinical-stage biopharmaceutical group developing new medicines and treatments to treat blood and autoimmune diseases. Hemogenyx Pharmaceuticals is developing several distinct and complementary product candidates, as well as platform technologies that it uses as engines for novel product development.