LONDON — September 21, 2026

PureTech Health announced the successful completion of an End-of-Phase 1 meeting with the U.S. FDA and receipt of Fast Track designation for LYT-200 in combination with a hypomethylating agent for patients with relapsed/refractory (R/R) high-risk myelodysplastic syndromes (HR-MDS). FDA feedback supports advancement of LYT-200 into the planned Phase 2 STRIDE-MDS trial, which will evaluate the fully human monoclonal antibody in a randomized, double-blind, placebo-controlled setting. LYT-200 targets galectin-9, an oncogenic driver and immunosuppressive protein, and is being advanced by PureTech’s Founded Entity, Gallop Oncology.

STRIDE-MDS to Evaluate Two LYT-200 Dose Regimens

The STRIDE-MDS Phase 2 trial is expected to enroll approximately 125 patients with R/R HR-MDS and will randomize participants 2:2:1 to LYT-200 at 12 mg/kg plus an HMA, LYT-200 at 7.5 mg/kg plus an HMA, or placebo plus an HMA. The study will evaluate efficacy based on complete and partial response rates and is designed to support dose selection. Its two-dose approach is also intended to address dose-selection requirements under the FDA’s Project Optimus framework. PureTech said the randomized design will enable assessment of the contribution of LYT-200 to treatment outcomes.

Phase 1b Data Support Continued Clinical Development

The planned Phase 2 program follows positive topline results from a Phase 1b study evaluating LYT-200 in combination with azacitidine or decitabine in heavily pretreated patients whose HR-MDS had relapsed or become refractory following prior HMA treatment. Among 11 efficacy-evaluable patients receiving LYT-200 at 12 mg/kg plus an HMA, the study reported a 27.3% complete response rate, 36.3% complete response plus partial response rate and 45.5% overall response rate. An 18% conversion-to-transplant rate was also reported, with no dose-limiting toxicities and no myeloid suppression observed in the evaluated population.

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PureTech Plans External Financing for LYT-200 Development

The FDA Fast Track designation provides PureTech and Gallop Oncology with opportunities for more frequent interactions with the agency during LYT-200 development, while the company prepares for the next clinical stage. PureTech intends to secure external capital in the first half of 2027 to support development of LYT-200 through completion of the Phase 2 trial. The candidate is being positioned as a mutation-agnostic approach for R/R HR-MDS, potentially addressing patients regardless of a specific actionable genetic mutation. LYT-200 has also received FDA Fast Track designation for acute myeloid leukemia (AML), expanding its potential development scope in hematologic malignan

Source :PureTech Health press release