On June 22, 2020 PureTech Health plc (LSE: PRTC) ("PureTech" or the "Company"), a clinical-stage biotherapeutics company dedicated to discovering, developing and commercializing highly differentiated medicines for devastating diseases, reported that new data establishing galectin-9 as a novel target for cancer immunotherapy and providing compelling evidence that therapies targeting galectin-9 may enable the immune system to attack an array of solid tumors (Press release, PureTech Health, JUN 22, 2020, View Source [SID1234561346]). The data were shared in a scientific poster presented at the June session of the American Association for Cancer Research (AACR) (Free AACR Whitepaper) 2020 Virtual Annual Meeting.

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PureTech is developing a first-in-class, fully human monoclonal antibody targeting galectin-9. The product candidate, LYT-200, is expected to enter a first-in-human, Phase 1a/1b study in 2020 in hard-to-treat cancers, including pancreatic, cholangiocarcinoma and certain types of colorectal and liver cancers, which remain insufficiently responsive or resistant to currently approved checkpoint inhibitors. PureTech has previously presented data demonstrating LYT-200’s efficacy in reducing tumor growth and reactivating human effector T cells in preclinical, patient-derived tumor culture models.

"These new data clearly establish the importance of galectin-9 as a therapeutic target, given that its high expression across tumor types correlates with poor patient outcomes. Our analysis of more than 1,000 samples from human breast cancer tumors found that high levels of galectin-9 are associated with shorter time to disease relapse as well as with a tumor microenvironment that lacks cytotoxic CD8+ T cells that would otherwise be able to attack the tumor," said Joseph Bolen, PhD, chief scientific officer at PureTech. "Our first-in-class monoclonal antibody, LYT-200, is designed to target and inhibit galectin-9 and thereby reverse this suppression of the immune system to boost its ability to destroy tumors. We’re proud to be presenting this research at AACR (Free AACR Whitepaper) and look forward to advancing LYT-200 into the clinic later this year, as well as to progressing our work on galectin-9 as a biomarker."

The AACR (Free AACR Whitepaper) poster details a study undertaken by PureTech and its academic collaborators to evaluate the importance of galectin-9 expression in the tissues of cancer patients. The study is believed to include the largest cohort of breast cancer patient samples ever evaluated in this context, as well as robust cohorts of pancreatic and cholangiocarcinoma cases, and it found high expression of galectin-9 across all of these tumor types. Importantly, the highest levels of galectin-9 correlated with shorter time to disease relapse and poor survival. Strong galectin-9 expression was observed on the membranes of tumors with poor prognosis, which indicates this target is attractive for an antibody therapeutic such as LYT-200. In breast cancer, galectin-9 expression was associated with tumors showing worse pathological features, such as high tumor grade and estrogen receptor negativity, as well as features characteristic of an immunosuppressed tumor microenvironment, including the absence of CD8+ T cells. Collectively, these data suggest that galectin-9 could be significant both as a therapeutic target for a range of cancers and as a cancer biomarker, which PureTech intends to explore further for patient stratification.