PureTech’s Founded Entity Gallop Oncology Announces Positive Initial Topline Data from Phase 1b Trial of LYT-200 in Relapsed/Refractory Acute Myeloid Leukemia and High-Risk Myelodysplastic Syndrome

PureTech Health plc (Nasdaq: PRTC, LSE: PRTC) ("PureTech" or the "Company"), a hub-and-spoke biotherapeutics company dedicated to giving life to science and transforming innovation into value, notes that its Founded Entity, Gallop Oncology, today announced initial topline results from the Phase 1b clinical trial evaluating LYT-200, a first-in-class anti-galectin-9 monoclonal antibody, in patients with relapsed/refractory acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS). The data demonstrated a favorable tolerability profile and strong efficacy, supporting the advancement of LYT-200 into a potentially registrational Phase 2 trial in AML. Additional details will be shared at the 67th American Society of Hematology (ASH) Annual Meeting on December 6^th, 2025.

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“Patients with relapsed/refractory AML or high-risk MDS face extremely limited treatment options, and overall survival at this stage is typically less than 2.5 months. With LYT-200, we have demonstrated durable responses, enabled a substantially meaningful proportion of patients to proceed to transplant, and shown initial median overall survival data of 13.2 months at the proposed Phase 2 dose - all alongside a very favorable safety profile. Together, these findings represent a potential step change in the treatment of AML,” said Luba Greenwood, JD, Chief Executive Officer of Gallop Oncology. “Importantly, these compelling results were observed in patients across several high-risk mutations, underscoring the central role of galectin-9 in driving this disease as well as the potential broad applicability of LYT-200 in AML and beyond. The strength of the data gives us confidence as we advance toward a potentially registrational Phase 2 study in AML and supports future evaluation of LYT-200 in earlier lines of treatment. We look forward to engaging with regulatory authorities once the maturing overall survival data are finalized.”

The Phase 1b, open-label, dose-escalation and dose-expansion trial evaluated LYT-200 both in combination with the standard-of-care (SOC) regimen of venetoclax (VEN) and a hypomethylating agent (HMA) and as a monotherapy in a heavily pretreated patient population (median prior lines of treatment: 3; range: 1-7).

TOPLINE SAFETY
LYT-200 demonstrated a favorable safety profile, with no LYT-200–related serious adverse events or dose-limiting toxicities observed in the trial (n=101). Importantly, no overlapping or additive toxicities were seen when LYT-200 was combined with VEN/HMA.