PureTech Announces Presentation of New Data Supporting Wholly Owned Immuno-Oncology Programs LYT-200 (anti-galectin-9) and LYT-210 (anti-delta-1)

Findings further validate targeting galectin-9 as therapeutic approach and biomarker for a number of difficult-to-treat cancers

Preclinical data show potency of LYT-210 against pathogenic γδ1 T cells, major sources of immunosuppression and resistance to immunotherapy in cancer

Posters Presented at Society for Immunotherapy of Cancer (SITC) 34^th Annual Meeting

BOSTON–(BUSINESS WIRE)–PureTech Health plc (LSE: PRTC) (“PureTech”), a clinical-stage biotechnology company dedicated to discovering, developing and commercializing highly differentiated medicines for devastating diseases, today announced the presentation of new preclinical data from its wholly-owned immuno-oncology programs at the Society for Immunotherapy of Cancer (SITC) 34^th Annual Meeting in National Harbor, Md.

The two scientific posters detail the Company’s continued progress in advancing two fully human monoclonal antibodies (mAbs) developed to inhibit two foundational immunosuppressive orchestrators, galectin-9 (LYT-200) and pathogenic gamma delta-1 (γδ1) T cells (LYT-210).

“These data further show the unique position and importance of galectin-9 and γδ1 as immunosuppressors in cancer biology. Both have been observed to have powerful properties to disable immune-mediated cancer attack, which may explain some of the fundamental efficacy limitations of other immuno-oncology therapies,” said Joseph Bolen, PhD, chief scientific officer at PureTech. “Our novel antibodies targeting galectin-9 and γδ1 have produced compelling single-agent preclinical data against a number of difficult-to-treat cancers in models where approved immunotherapies haven’t worked. We are excited to share our continued progress with the scientific community at premier conferences such as SITC.”

The new data presented at SITC indicate that galectin-9 is not only a potent therapeutic target, but also a potentially relevant biomarker. Across multiple cohorts, galectin-9 was significantly increased in blood samples of individuals with primary and metastatic pancreatic cancer, lung tumors, and colorectal carcinoma, compared to healthy individuals.

“These findings validate the importance of galectin-9 in cancer biology and its potency as a target,” said George Miller, MD, Director of S. Arthur Localio Laboratories and Director of the Cancer Immunology Program at NYU School of Medicine and a PureTech collaborator. “Our research indicates that galectin-9 is a master immunosuppressor; it induces a highly favorable microenvironment for tumor growth. LYT-200 has potential both as a single agent and in combination with checkpoint inhibitors to have therapeutic potential by reversing the immunosuppression which can be present in the tumor microenvironment.”

PureTech expects to file an Investigational New Drug application (IND) for LYT-200 in the first half of 2020 and to initiate a Phase 1a/1b clinical trial in solid tumors in 2020. The mAb has been tested as a single agent as well as in combination with anti-PD1 checkpoint inhibitors in preclinical murine and human-derived ex vivo models, showing robust and reproducible activity, immune activation potential as well as excellent drug properties.

PureTech also presented data on its monoclonal antibody LYT-210 that targets γδ1 T cells whose immunosuppressive features leads to a tumor permissive microenvironment. The research presented at SITC showed that γδ1 T cells were the most abundant T cell within the studied tumors, which included pancreatic, colorectal, cholangiocarcinoma, and liver cancer, and represented up to 50% of all infiltrating T cells. PureTech also presented data showing that LYT-210 depletes immunosuppressive γδ1 T cells through cytotoxicity and phagocytosis. Together, these findings further support the ability of LYT-210 to potentially restore the immune system’s ability to fight difficult-to-treat cancers. PureTech expects to file an IND for LYT-210 in 2021 for solid tumors.

“These data show that γδ1 cells play a key role in suppressing the immune system’s ability to attack tumors. LYT-210 is designed to remove and destroy pathogenic γδ1 T cells enabling immune mediated cancer attack. We therefore believe LYT-210 holds significant promise as a potential immunotherapy,” said Dr. Miller.

About PureTech

PureTech is a clinical stage biotechnology company dedicated to discovering, developing and commercializing 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 affiliates, is comprised of 24 product candidates and one product that has been cleared by the US Food and Drug Administration (FDA). All of the underlying programs 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.

Forward Looking Statement

This press release contains statements that are or may be forward-looking statements, including statements that relate to the company’s future prospects, developments, and strategies. The forward-looking statements are based on current expectations and are subject to known and unknown risks and uncertainties that could cause actual results, performance and achievements to differ materially from current expectations, including, but not limited to, those risks and uncertainties described in the risk factors included in the regulatory filings for PureTech Health plc. These forward-looking statements are based on assumptions regarding the present and future business strategies of the company and the environment in which it will operate in the future. Each forward-looking statement speaks only as at the date of this press release. Except as required by law and regulatory requirements, neither the company nor any other party intends to update or revise these forward-looking statements, whether as a result of new information, future events or otherwise.

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