Pionyr Immunotherapeutics Doses First Patient in Phase 1b Expansion Study of PY314

SOUTH SAN FRANCISCO, Calif., March 8, 2022 /PRNewswire/ -- Pionyr Immunotherapeutics, Inc., a company developing first-in-class Myeloid Tuning^TM antibody therapeutics that enhance the body's antitumor immunity by altering, or "tuning", immune cells within the tumor microenvironment, announced today that the first patient has been dosed in Phase 1b expansion studies investigating PY314 in patients with solid tumors.

PY314 is a monoclonal antibody that binds Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) on the surface of immunosuppressive, pro-tumor myeloid cells, and is designed to deplete TREM2-expressing tumor associated macrophages (TAMs), leading to productive anti-tumor immunity. Preclinical data generated by Pionyr suggest that when TAMs are depleted from tumors, pro-inflammatory, anti-tumor immune cells such as CD8 T-cells, natural killer (NK) and M1-like macrophages become activated and penetrate tumors leading to tumor destruction.

This Phase 1b portion of the study follows Pionyr's Phase 1a dose escalation trial which evaluated the safety and tolerability of PY314 alone and in combination with pembrolizumab in multiple solid tumors. The multi-centered, US-based Phase 1a study has completed enrollment and determined a recommended Phase 1b dose for expansion.

"Dosing the first patient in our Phase 1b expansion study is an important milestone for the clinical development of PY314, having passed the first safety analysis and identifying a recommended dose for further evaluation," said Leonard Reyno, M.D., Executive Vice President and Chief Medical Officer, Pionyr. "PY314 represents an opportunity to expand immunotherapy options for patients with advanced solid tumors, which continues to represent a major unmet need, especially among patients with checkpoint resistant tumors. We are excited to begin this expansion study with leading clinical sites and investigators who have enthusiastically joined in this effort alongside us." 

The Phase 1b study will evaluate PY314 administered alone and in combination with pembrolizumab in predefined tumor types, including ovarian, breast, lung, renal, and colorectal cancers. The first patient has been dosed as a single agent in advanced ovarian cancer and combination cohorts have begun enrollment. In addition to characterizing the anti-tumor activity of PY314, this study will continue to evaluate the safety, tolerability and pharmacokinetics of PY314. Additional exploratory biomarkers will be evaluated, including analysis of TREM2-expressing macrophages in tumor biopsy samples. For more information, please visit www.clinicaltrials.gov (Identifier: NCT04691375).

"PY314 is intended to clear the way for pro-inflammatory, anti-tumor immune cells to take control of the tumor microenvironment and destroy tumor cells," said Alicia Levey, Ph.D., Chief Operating Officer, Pionyr.  "As a further demonstration of our Myeloid Tuning^TM platform, we also expect to initiate an expansion study in the first half of 2022 of our PY159 program, which 'turbocharges' anti-tumor activity by reprogramming TREM1-expressing immunosuppressive myeloid cells."

About Pionyr Immunotherapeutics

Pionyr is exploiting novel target discovery and antibody generation platform technologies to create the next generation of immuno-oncology therapeutics after checkpoint inhibitors. The company's initial approach, termed "Myeloid Tuning^TM," is designed to enhance the immune system's anti-tumor response by specifically altering the cellular infiltrate of the tumor microenvironment. Pionyr's lead programs PY314 and PY159, targeting TREM2 and TREM1 respectively, are designed to selectively deplete and in some cases reprogram certain tumor-associated macrophages responsible for immunosuppression. In July 2020, Pionyr entered into a transformational alliance with Gilead Sciences whereby Gilead acquired a minority interest in the company and has an exclusive option to acquire Pionyr upon completion of certain Phase 1b studies. Pionyr's additional investors include New Enterprise Associates, OrbiMed, SV Health Investors, Sofinnova Ventures, Vida Ventures, Osage University Partners, Mission Bay Capital, and Trinitas Ventures. For more information, please visit www.pionyrtx.com.

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SOURCE PIONYR Immunotherapeutics, Inc.