Boston — PureTech Health said its Founded Entity Gallop Oncology reported initial topline results from a Phase 1b trial of LYT-200, an anti–galectin-9 monoclonal antibody, in patients with relapsed/refractory acute myeloid leukemia (AML) and high‑risk myelodysplastic syndrome (MDS). The data show a favorable tolerability profile and evidence of antileukemic activity in a heavily pretreated population, supporting advancement toward a potentially registrational Phase 2 trial.
The open‑label, dose‑escalation and dose‑expansion study evaluated LYT-200 both in combination with venetoclax (VEN) and a hypomethylating agent (HMA) and as monotherapy. Median prior lines of treatment was three (range 1–7). A total of 101 patients were treated for safety assessment.
Safety results indicated no LYT-200‑related serious adverse events or dose‑limiting toxicities and no overlapping or additive toxicities when combined with VEN/HMA.
In combination cohorts, 87.5% of patients had prior exposure to VEN/HMA. Across 43 evaluable patients treated with LYT-200 plus VEN/HMA, the combined complete response rate (CR + CRi) was 33%. Half of patients achieving a complete response proceeded to stem cell transplant. Responses were observed across diverse high‑risk mutations, including KRAS, NRAS, JAK2 and KIT.
At the proposed Phase 2 dose of 12 mg/kg (32 evaluable patients), the combination produced a 38% combined complete response rate, a 97% disease control rate, and an initial median overall survival of 13.2 months. Overall survival data at this dose continue to mature, with final results expected in the first half of 2026.
As monotherapy (26 evaluable patients), LYT-200 demonstrated clinical activity and disease stabilization in patients with heavily pretreated disease. Median overall survival in the monotherapy cohort was 6.5 months. One partial response has been maintained for 27 months in a patient whose disease had progressed after five prior lines of therapy.
LYT-200 has been granted Fast Track and Orphan Drug designations by the U.S. Food and Drug Administration for the treatment of AML. Gallop plans to engage with regulatory authorities to discuss the proposed Phase 2 dose and a potential registrational path once overall survival data have fully matured.
Full trial details will be presented at the 67th American Society of Hematology Annual Meeting on December 6, 2025; the poster will be made available on Gallop’s website.
Acute myeloid leukemia is an aggressive blood cancer with poor outcomes in the relapsed/refractory setting. New therapies that improve durability and broaden applicability across mutation profiles remain an unmet need.
LYT-200 is a fully human IgG4 monoclonal antibody that targets galectin‑9, a protein implicated in tumor cell survival and immune suppression. Blocking galectin‑9 is intended to have both direct antitumor and immune‑restorative effects.
Gallop Oncology is a clinical‑stage biopharmaceutical company focused on treatments for hematologic malignancies. Gallop was founded by and is wholly owned by PureTech Health.
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