PureTech Presents Data from Phase 1 Trial of LYT-200 Targeting Galectin-9 in Solid Tumors at the ESMO Immuno-Oncology Congress 2023

PureTech Health plc (Nasdaq: PRTC, LSE: PRTC) ("PureTech" or the "Company"), a clinical-stage biotherapeutics company dedicated to changing the lives of patients with devastating diseases, today announced a poster presentation with results from the Phase 1 portion of the Phase 1/2 dose escalation and expansion clinical trial of LYT-200 at the ESMO Immuno-Oncology Congress 2023. LYT-200 is an anti-galectin-9 antibody being evaluated as a monotherapy and in combination with tislelizumab, an anti-PD-1 antibody developed by BeiGene, in metastatic solid tumors, including urothelial and head and neck cancers. LYT-200 is also in development for the treatment of hematological malignancies, such as acute myeloid leukemia.

The data being presented from an ongoing study including all evaluable patients demonstrate that LYT-200 has a favorable safety profile in all cohorts, including the monotherapy and combination arms, and shows disease control and initial anti-tumor activity in combination with tislelizumab. In the combination cohort, anti-tumor activity was observed in patients with relapsed or refractory head and neck squamous cell carcinoma, a patient population that has historically demonstrated a low response rate to anti-PD-1 agents of around 20 percent and 10 percent with chemotherapy¹.

“Galectin-9 is thought to play a foundational role in suppressing immune-mediated activity against tumor cells, and increases in galectin-9 expression have been shown to correlate with aggressive disease and higher mortality, as is seen in patients with head and neck and urothelial cancers,” said Julie Krop, M.D., Chief Medical Officer at PureTech Health. “LYT-200 is the most advanced clinical program against this target, and we are very encouraged by the initial results and look forward to completing this study and advancing this program into late-stage development.”

The Phase 1/2 clinical trial includes a dose finding/dose escalation phase (part 1) and an expansion cohort phase (part 2) in patients with relapsed and refractory, locally advanced/metastatic solid tumors. In the monotherapy cohort, 20 patients received LYT-200 across seven escalation doses, with dose levels of 0.2 mg/kg to 16 mg/kg once every two weeks or 10 mg/kg once a week. LYT-200 was well-tolerated with no observed dose-limiting toxicities and only low-grade adverse events, as well as long-term disease stabilization exceeding one year in patients with heavily pre-treated pancreatic cancer and in one patient with colorectal cancer. The monotherapy arm of the trial has been completed, and the clinically relevant dose was selected for the Phase 2 portion of the trial.