Pionyr Immunotherapeutics announced the initiation of a Phase 1 clinical study investigating PY314 in patients with solid tumors.

PY314 targets TREM2, a protein found on the surface of a subpopulation of immunosuppressive, pro-tumor myeloid cells. PY314 works by depleting TREM2-expressing immune suppressive tumor associated macrophages (TAMs), which leads to activation of productive anti-tumor immunity. In preclinical studies, PY314 treatment not only depleted TAMs, but also promoted infiltration of activated anti-tumor cytotoxic T lymphocytes into the tumor microenvironment.

"Pionyr moving PY314 into clinical development is a major milestone for our company and our scientific platform," said Steven P. James, President and Chief Executive Officer, Pionyr. "This study initiation also comes shortly after receiving the FDA clearance of our Investigational New Drug (IND) Application for our second antibody program, PY159, which 'turbocharges' anti-tumor activity by targeting TREM1-expressing myeloid cells in the tumor microenvironment. With the acceptance of two INDs in two months, the start of the PY314 Phase 1 trial and the anticipated initiation of the PY159 trial by year end, we are rapidly advancing our mission of creating the new frontier of immuno-oncology therapies."

The Phase 1 study will enroll patients at multiple academic centers in the US and will evaluate PY314 as both a single agent and in combination with an approved checkpoint inhibitor. Once safety is determined, additional patients will be recruited in predefined tumor types where TREM2 expression is most likely implicated as a driver of resistant metastatic disease.

"PY314 represents a potentially foundational therapeutic opportunity to expand immunotherapy options for patients with advanced solid tumors," said Leonard Reyno, M.D., Senior Vice President and Chief Medical Officer, Pionyr. "We are excited to make this transition into a clinical-stage company and work with the leading clinical sites and investigators who have enthusiastically joined in this effort alongside us."