PRTC's Gallop to Present Ph1b LYT-200 Data at ESMO

PureTech Announces Presentation of Phase 1b Results for LYT-200 in Relapsed/Refractory (R/R) High-Risk Myelodysplastic Syndromes (HR-MDS) and Acute Myeloid Leukemia (AML) at ESMO 2026

Oral presentation to highlight encouraging clinical activity and favorable safety of LYT-200 in heavily pretreated patients with R/R HR-MDS and AML

Results reinforce the potential of LYT-200 as a first-in-class, mutation-agnostic treatment for a broad R/R HR-MDS population, where treatment options remain extremely limited

PureTech Founded Entity, Gallop Oncology, plans to advance LYT-200 into Phase 2 STRIDE-MDS trial in patients with R/R HR-MDS following successful FDA End-of-Phase 1 meeting and receipt of Fast Track designation

PureTech Health plc (LSE: PRTC) ("PureTech" or the "Company"), a hub-and-spoke biotherapeutics company dedicated to giving life to science and transforming innovation into value, today announced that results from the completed Phase 1b clinical trial of LYT-200 will be presented at the European Society for Medical Oncology (ESMO) Congress 2026, taking place October 23-27 in Madrid, Spain. LYT-200 is a first-in-class monoclonal antibody targeting galectin-9, an important oncogenic driver and potent immunosuppressor, being advanced by PureTech's Founded Entity, Gallop Oncology (Gallop).

"The Phase 1b results provide a strong foundation for the continued development of LYT-200, particularly in relapsed/refractory high-risk MDS, where patients have extremely limited treatment options," said Aleksandra Filipovic, MD, PhD, Head of Oncology at PureTech and Chief Medical Officer of Gallop Oncology. "The encouraging clinical activity observed, together with the favorable safety profile, reinforces our confidence in the potential of LYT-200 to offer a differentiated treatment approach for a broad population of patients, regardless of mutation status. We look forward to sharing these findings with the oncology community in an oral presentation at ESMO as we prepare to advance LYT-200 into Phase 2 development."

Details of the presentation are as follows:

Title: Topline Results from a Phase 1b Study of LYT-200 (Anti-Galectin-9 mAb) Alone and with HMA ± Venetoclax in Relapsed/Refractory High-Risk MDS and AML

Presenter: Guenther Koehne, MD, PhD, Deputy Director and Chief of Blood & Marrow Transplant and Hematologic Oncology at Baptist Health Herbert Wertheim Cancer Institute

Session: Proffered Paper: Hematological Malignancies (located at Salamanca Auditorium - Hall 10)

Date and Time: October 24, 2026, 8:30 AM - 10:00 AM CEST

About LYT-200

LYT-200 is a Phase 2-ready, fully human monoclonal antibody in development for the treatment of relapsed/refractory (R/R) high-risk myelodysplastic syndromes (HR-MDS). It is the most advanced therapeutic candidate targeting galectin-9, which is an important oncogenic driver and potent immunosuppressor that plays a central role in some of the most difficult-to-treat cancers. With its mutation-agnostic, dual mechanism of action, LYT-200 is designed to address both the malignant cells and the immunosuppressive environment that sustain disease. LYT-200 has been granted Fast Track designation from the U.S. Food and Drug Administration (FDA) for the treatment of R/R HR-MDS in combination with a hypomethylating agent. LYT-200 has also been granted Fast Track designation from the U.S. FDA for the treatment of acute myeloid leukemia (AML).

About Gallop Oncology

Gallop Oncology is a clinical-stage biotechnology company dedicated to transforming the treatment paradigm for hematological malignancies. Its lead candidate, LYT-200, is a first-in-class, mutation-agnostic antibody in development for the treatment of relapsed/refractory (R/R) high-risk myelodysplastic syndromes (HR-MDS). Gallop Oncology was founded by and is currently wholly owned by PureTech Health plc (LSE: PRTC). For more information, please visit www.galloponcology.com.