BOSTON — PureTech Health plc reported positive topline results from a Phase 1b clinical trial of its investigational therapy LYT-200, showing encouraging signs of effectiveness and a favorable safety profile in patients with advanced blood cancers who had limited treatment options.
The study evaluated LYT-200, a first-in-class monoclonal antibody targeting galectin-9, in patients with relapsed or refractory high-risk myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). These patients had undergone multiple prior treatments and typically face poor outcomes.
In patients with high-risk MDS, the therapy demonstrated a 45.5 percent overall response rate, including complete, partial, and marrow responses. Among AML patients, the overall response rate was 42.3 percent, with a composite complete response rate of 30.8 percent. Some patients were able to proceed to stem cell transplant following treatment.
The company said the treatment showed a favorable and consistent safety profile, with no dose-limiting toxicities, treatment-related serious adverse events, or discontinuations reported. While some patients experienced higher-grade blood-related side effects, these were consistent with the underlying diseases and commonly seen in this patient population.
“The data from the completed Phase 1b trial highlight the potential for LYT-200 to offer a differentiated treatment approach across a range of myeloid hematological malignancies,” said Aleksandra Filipovic, M.D., Ph.D., Head of Oncology at PureTech and Chief Medical Officer of Gallop Oncology. “Across patients with R/R HR-MDS and R/R AML, treatment with LYT-200 resulted in deep responses with an exceptionally favorable safety profile. Importantly, the data in R/R HR-MDS were particularly compelling and support prioritizing this indication, especially given the significant unmet need and lack of successful innovation to help these patients. We intend to engage with the FDA to discuss the design of a subsequent trial in R/R HR-MDS, as our goal is to accelerate delivery of this promising first-in-class therapy to patients while also laying the foundation for broader clinical development, including in AML.”
Amir T. Fathi, M.D., Program Director of the Center for Leukemia at the Mass General Brigham Cancer Institute, said the findings are notable given the limited treatment options for high-risk MDS.
“The safety profile, combinatorial potential, and level of clinical activity observed with LYT-200 in this Phase 1b study across both R/R HR-MDS and R/R AML is very encouraging, particularly given the number of prior lines of treatment and the risk profile in the populations studied,” Fathi said. “In R/R high-risk MDS, where treatment options are extremely limited and outcomes are poor, the findings are particularly notable. In this context, the potential to achieve clinical responses without added toxicity would represent a meaningful advance in the MDS treatment landscape and warrants continued clinical development.”
PureTech said it plans to meet with the U.S. Food and Drug Administration to discuss the design of a subsequent trial aimed at supporting potential regulatory approval, with an initial focus on high-risk MDS. Company officials added that the results provide a foundation for advancing LYT-200 into later-stage development while continuing to explore its use in other blood cancers.
