PureTech Health presents new data on clinical potential of LYT-200

PureTech Health shared new data supporting the clinical potential of LYT-200, a fully human monoclonal antibody, or mAb, designed to inhibit the activity of galectin-9, as a therapeutic agent for the treatment of leukemia. The data were shared in a scientific poster presented at the American Society of Hematology, or ASH, 64th Annual Meeting. LYT-200 is a therapeutic candidate targeting galectin-9, which is expressed by tumors and immune cells and plays a key role in cancer treatment resistance. It is also in development as a treatment for a range of cancer indications with otherwise poor survival rates. The ASH poster evaluates galectin-9 expression and the effects of LYT-200 in multiple types of leukemia. Compared to healthy human peripheral blood mononuclear cells, where galectin-9 surface expression was low or absent, galectin-9 was highly expressed on the surface of all human blood cancer cells tested. Notably, surface expression of galectin-9 often exceeded that of the known inhibitory checkpoint proteins TIM-3 and PD-1. In all models used, LYT-200 demonstrated significant anti-tumor activity and in addition to its established effects on the immune system in solid tumor models, it also notably induced direct apoptosis or cell death across all leukemia cell types. In a model assessing DNA damage in AML cells, LYT-200 significantly outperformed an anti-TIM3 antibody and had effects that were comparable to Venetoclax, an approved therapeutic for AML. The effects were greatest when both compounds were combined. The in vitro efficacy of LYT-200 against the leukemia subtypes also extended to in vivo survival benefit in both immunocompromised and immunocompetent patient-derived xenograft mouse models. In these models, LYT-200 outperformed chemotherapy and produced the greatest effect in combination. Collectively, these new data support galectin-9 as a strong potential therapeutic target for a range of cancers. Based on this and other preclinical data generated with LYT-200 in blood cancers, PureTech has initiated a clinical trial to evaluate LYT-200 as a single agent for the treatment of AML with results expected in 2023. PureTech has also completed the bi-monthly and weekly, monotherapy dose escalation portion of the Phase 1 program assessing the safety and tolerability of escalating doses of LYT-200 as a potential treatment of metastatic solid tumors. No dose-limiting toxicities were reported, and the full results will be presented in an upcoming scientific forum. The combination part of the Phase 1 trial in certain metastatic solid tumors with LYT-200 in combination with tislelizumab is expected to begin in the first quarter of 2023.