Pionyr Immunotherapeutics Presents on Third Myeloid-Directed Therapeutic Program at Keystone Symposium

  • PY265 program further demonstrates Pionyr’s Myeloid Tuning platform to enhance antitumor immunity

SOUTH SAN FRANCISCO, CA, March 22, 2022 – 

Pionyr Immunotherapeutics, Inc., a company developing first-in-class Myeloid TuningTM antibody therapeutics that enhance the body’s antitumor immunity by altering, or “tuning”, immune cells within the tumor microenvironment, announced today preclinical results from its PY265 program demonstrating efficacy both as single-agent and in combination with anti-PD1. The latest preclinical research from the program was presented in a poster at the Keystone Symposium titled Cancer Immunotherapy: Decoding the Cancer Immunity Interactome and in a talk today, March 22.

“PY265 further demonstrates our Myeloid Tuning platform by engaging the macrophage receptor, MARCO, to repolarize immunosuppressive myeloid populations in the tumor and induce rapid immune activation,” said Kevin P. Baker, Ph.D., SVP and Chief Development Officer at Pionyr. “Our lead programs, PY314 (anti-TREM2) and PY159 (anti-TREM1), are currently in the clinic, and PY265 is on track to complete IND-enabling studies and enter the clinic in 2023.”

PY265 targets the macrophage receptor with collagenous structure (MARCO), leveraging a distinct mechanism of action from other myeloid-directed therapeutics currently in development and is expected to be first-in-class. MARCO is expressed on immunosuppressive tumor associated macrophages (TAMs) and monocytic myeloid-derived suppressor cells (mMDSCs), and its expression correlates with aggressive and advanced disease. These subpopulations of tumor myeloid cells are different from those that express the targets of Pionyr’s current lead clinical programs, TREM1 and TREM2. By targeting MARCO, PY265 induces immune activation by reprogramming pro-tumorigenic, M2-like TAMs and mMDSCs to pro-inflammatory macrophages and monocytes, leading to an increase in intra-tumoral infiltration of activated CD8+ T cells and NK cells.

The poster presentation is available on the company website at

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 TuningTM,” 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

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