PRTC Presents New Immuno-oncology Data at AACR

22 June 2020

PureTech Health plc

PureTech Presents New Data Reinforcing Galectin-9 as a Compelling Therapeutic Target and Biomarker for a Range of Cancers at the American Association for Cancer Research Annual Meeting

Data include largest cohort of breast cancer samples ever evaluated in this context and demonstrate that high levels of galectin-9 are associated with shorter time to disease relapse

Wholly-owned novel monoclonal antibody (LYT-200) is designed to selectively inhibit galectin-9, with a first-in-human clinical trial expected to begin in 2H 2020

PureTech Health plc (LSE: PRTC) ("PureTech" or the "Company"), a clinical-stage biotherapeutics company dedicated to discovering, developing and commercialising highly differentiated medicines for devastating diseases, today shared 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 tumours. The data were shared in a scientific poster presented at the June session of the American Association for Cancer Research (AACR) 2020 Virtual Annual Meeting.

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 tumour growth and reactivating human effector T cells in preclinical, patient-derived tumour culture models.

"These new data clearly establish the importance of galectin-9 as a therapeutic target, given that its high expression across tumour types correlates with poor patient outcomes. Our analysis of more than 1,000 samples from human breast cancer tumours found that high levels of galectin-9 are associated with shorter time to disease relapse as well as with a tumour microenvironment that lacks cytotoxic CD8+ T cells that would otherwise be able to attack the tumour," 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 tumours. We're proud to be presenting this research at AACR 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 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 tumour 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 tumours 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 tumours showing worse pathological features, such as high tumour grade and estrogen receptor negativity, as well as features characteristic of an immunosuppressed tumour 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.

About PureTech Health

PureTech is a clinical-stage biotherapeutics company dedicated to discovering, developing and commercialising highly differentiated medicines for devastating diseases, including intractable cancers, lymphatic and gastrointestinal diseases, central nervous system disorders and inflammatory and immunological diseases, among others. The Company has created a broad and deep pipeline through the expertise of its experienced research and development team and its extensive network of scientists, clinicians and industry leaders. This pipeline, which is being advanced both internally and through PureTech's Founded Entities, is comprised of 24 products and product candidates, including two that have been cleared by the US Food and Drug Administration (FDA). All of the underlying programmes and platforms that resulted in this pipeline of product candidates were initially identified or discovered and then advanced by the PureTech team through key validation points based on the Company's unique insights into the biology of the brain, immune and gut, or BIG, systems and the interface between those systems, referred to as the BIG Axis.

For more information, visit www.puretechhealth.com or connect with us on Twitter @puretechh.

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