PureTech Presents Clinical Trial Design Supporting Wholly Owned Immuno-Oncology Candidate LYT-200 at the Society for Immunotherapy of Cancer (SITC) 36th Annual Meeting

LYT-200 is being advanced in a range of difficult-to-treat solid tumors including pancreatic cancer, colorectal cancer and cholangiocarcinoma

Phase 1 portion of its adaptive Phase 1/2 trial with LYT-200 in solid tumors continues to progress, with a maximum tolerated dose not yet reached

PureTech Health plc (Nasdaq: PRTC, LSE: PRTC) ("PureTech" or the "Company"), a clinical-stage biotherapeutics company dedicated to discovering, developing and commercializing highly differentiated medicines for devastating diseases, today announced that a poster presentation describing the adaptive Phase 1/2 trial of LYT-200 for the potential treatment of difficult-to-treat solid tumors will be given at the Society for Immunotherapy of Cancer (SITC) 36^th annual meeting.

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PureTech announced that a poster presentation describing the Phase 1/2 trial of LYT-200 for the potential treatment of difficult-to-treat solid tumors, including pancreatic cancer, colorectal cancer and cholangiocarcinoma, will be given at the Society for Immunotherapy of Cancer (SITC) 36th annual meeting. (Graphic: Business Wire)

The scientific poster to be presented at SITC details the Company’s adaptive Phase 1/2 clinical trial of LYT-200, an investigational monoclonal antibody targeting galectin-9, which is an immunosuppressive protein prominently expressed in multiple difficult-to-treat cancers, including, but not limited to, pancreatic cancer, cholangiocarcinoma, and breast cancer. The clinical study includes a dose finding/dose escalation phase (part 1) and an expansion cohort phase (part 2) in patients with relapsed and refractory metastatic solid tumors. The trial will assess the safety, tolerability, pharmacokinetics, pharmacodynamics, immunogenicity and preliminary anti-tumor activity of LYT-200 both as a single agent and in combination with either BeiGene’s tislelizumab or chemotherapy. Topline results from the Phase 1 portion of the study are now expected in the first half of 2022 to allow for continued dose escalation as a maximum tolerated dose has not yet been reached.

“PureTech’s preclinical data package elegantly supports the significance of galectin-9 as a therapeutic target, showing it is a multifaceted immunosuppressor in cancer biology and potential biomarker of prognosis,” said Zev Wainberg, M.D., Professor of Medicine at UCLA and Co-director of the UCLA GI Oncology Program and the lead primary investigator of the study.

“High galectin-9 levels in patients have been associated with a worse prognosis, and our anti-galectin-9 research candidates outperformed approved immunotherapies in multiple preclinical models of difficult-to-treat cancers, giving us confidence as we moved into the clinical phase to establish key safety and therapeutic parameters and initial insights into efficacy,” said Aleksandra Filipovic, M.D., Ph.D., Head of Oncology at PureTech.

Part 1 is a dose-finding study being conducted using a reassessment method to evaluate safety and establish the recommended Phase 2 dose. Two to six patients per treatment cohort are assigned to receive sequentially higher intravenous infusions of LYT-200 every two weeks on day one and day 15 of each 28-day cycle, starting at a dose of 0.2 mg/kg, with escalating dose cohorts up to 16 mg/kg. Part 1 will be completed when six consecutive patients have received the optimal biologic dose and/or the maximal tolerated dose. The study is currently evaluating patients enrolled in the fourth cohort of part 1 at an active dose measuring 6.3 mg/kg. The Phase 2 portion of the study is currently planned to enroll patients with a range of solid tumor types, including pancreatic cancer and other GI solid tumor types.

The U.S. Food and Drug Administration (FDA) recently granted orphan drug designation for LYT-200 for the treatment of pancreatic cancer. The FDA grants orphan drug designation to novel drug and biologic products for the treatment, diagnosis or prevention of conditions affecting fewer than 200,000 persons in the U.S. Orphan drug designation qualifies PureTech for incentives under the Orphan Drug Act, including tax credits for some clinical trials and eligibility for seven years of market exclusivity in the U.S. if the drug is approved.

About LYT-200

LYT-200 is a fully human IgG4 monoclonal antibody targeting a foundational immunosuppressive protein, galectin-9, for the potential treatment of solid tumors, including pancreatic ductal adenocarcinoma, colorectal cancer and cholangiocarcinoma, that are difficult to treat and have poor survival rates. PureTech has presented preclinical data demonstrating high expression of galectin-9 across breast cancer, pancreatic and cholangiocarcinoma samples and found that the highest levels of galectin-9 correlated with shorter time to disease relapse and poor survival. These data suggest that galectin-9 could be significant both as a therapeutic target for a range of cancers and as a cancer biomarker. Preclinical animal and patient-derived organoid tumor models also showed the potential efficacy of LYT-200 and the importance of galectin-9 as a target. LYT-200 is currently being evaluated in a Phase 1/2 adaptive design trial, and results from the Phase 1 portion of the dose escalation trial are expected in the first half of 2022.

About PureTech Health

PureTech is a clinical-stage biotherapeutics company dedicated to discovering, developing and commercializing highly differentiated medicines for devastating diseases, including inflammatory, fibrotic and immunological conditions, intractable cancers, lymphatic and gastrointestinal diseases and neurological and neuropsychological disorders, 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 25 therapeutics and therapeutic candidates, including two that have received both U.S. FDA clearance and European marketing authorization, as of the date of PureTech's most recently filed Half Year Report and corresponding Form 6-K. All of the underlying programs and platforms that resulted in this pipeline of therapeutic 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

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation statements that relate to our expectations regarding the potential therapeutic benefits of LYT-200 in patients with solid tumors, the design of the Company’s adaptive design Phase 1/2 trial for LYT-200, the progression and expected timing of results from our Phase 1/2 trial of LYT-200, and any incentives that the Company may receive as a result of LYT-200 receiving orphan drug designation. The forward-looking statements are based on current expectations and are subject to known and unknown risks, uncertainties and other important factors that could cause actual results, performance and achievements to differ materially from current expectations, including, but not limited to, those risks, uncertainties and other important factors described under the caption "Risk Factors" in our Annual Report on Form 20-F for the year ended December 31, 2020 filed with the SEC and in our other regulatory filings. 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, we disclaim any obligation to update or revise these forward-looking statements, whether as a result of new information, future events or otherwise.

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