– Collaboration will evaluate combination of SNDX-6352 with durvalumab (ImfinziTM) in solid tumors –

WALTHAM, MA, USA I February 1, 2018 I Syndax Pharmaceuticals, Inc. (“Syndax,” the “Company” or “we”) (Nasdaq: SNDX), a clinical stage biopharmaceutical company developing an innovative pipeline of cancer therapies, today announced a new clinical collaboration with AstraZeneca  to evaluate the safety and efficacy of AstraZeneca’s durvalumab, a human monoclonal antibody directed against programmed death-ligand 1 (PD-L1), in combination with SNDX-6352, Syndax’s monoclonal antibody inhibitor of Colony-Stimulating Factor 1 Receptor (CSF1R), across a variety of solid tumors.

Under the terms of the agreement, Syndax and AstraZeneca will collaborate on a non-exclusive basis to evaluate the combination of the two drugs in multiple solid tumor types. Syndax expects to initiate a Phase Ib study in the first half of 2018 to establish the safety and recommended dose regimen of SNDX-6352 in combination with durvalumab. Data from this study will enable both companies to sponsor, design and initiate subsequent Phase II studies aimed at exploring the safety and efficacy of the combination across a number of defined tumor types.

“It is thought that tumor associated macrophages (TAMs) mediate immunosuppressive effects in the tumor microenvironment, which may limit the benefit of some immunotherapies, including those targeting PD-L1. SNDX-6352 has been shown to reduce the activity of TAMs, which we hope will translate to improved patient outcomes,” said Briggs W. Morrison, M.D., Chief Executive Officer of Syndax. “This collaboration seeks to determine whether SNDX-6352 combined with durvalumab could offer patients a greater benefit than either therapy alone, in specific clinical settings. We look forward to working closely with AstraZeneca to address this important question.”

Financial and other terms of the agreement were not disclosed.

About SNDX-6352

SNDX-6352 is a monoclonal antibody that blocks the colony stimulating factor 1 (CSF-1) receptor. Inhibition of signaling through the CSF-1 receptor has been shown to lead to the depletion of cells known as Tumor Associated Macrophages, or TAMS, immunosuppressive cells found in the tumor microenvironment that can inhibit the ability of Tumor Infiltrating Lymphocytes to attack and kill tumor cells. SNDX-6352 is currently being evaluated in a Phase 1 multiple ascending dose clinical trial, and is expected to be developed to treat a variety of solid tumor and immune-related diseases.

About Syndax Pharmaceuticals, Inc.

Syndax Pharmaceuticals is a clinical stage biopharmaceutical company developing an innovative pipeline of cancer therapies. The Company is developing its lead product candidate, entinostat, a once-weekly, oral, small molecule, class I HDAC inhibitor, in combination with exemestane and several approved PD-1/PD-L1 antagonists. The Company’s pipeline also includes SNDX-6352, a monoclonal antibody that blocks the colony stimulating factor 1 (CSF-1) receptor, as well as a portfolio of potent and selective inhibitors targeting the binding interaction of Menin with MLLr. For more information, please visit www.syndax.com or follow the Company on Twitter and LinkedIn.

SOURCE: Syndax Pharmaceuticals