Gilead Sciences has agreed to acquire a 49.9% equity interest and hold an exclusive option to purchase the remaining equity in Pionyr Immunotherapeutics for $275m.

Under the terms of the agreement, Gilead would pay up to an additional $1.47bn in option exercise fees and future milestone payments for Pionyr shareholders.

Gilead Sciences chairman and CEO Daniel O’Day said: “Pionyr is pursuing promising, novel biology in the field of immuno-oncology.

“The agreement represents important progress as we continue to build out Gilead’s presence in immuno-oncology with innovative and complementary approaches. We look forward to seeing the programs advance with the goal of developing new therapies that will improve the treatment of cancer.”

Pionyr develops Myeloid Tuning to rebalance the tumour microenvironment (TME)

Pionyr is a privately held pharmaceutical company, engaged in developing a research approach called Myeloid Tuning, to rebalance the tumour microenvironment (TME) and promote anti-tumour immunity.

Myeloid Tuning therapies are said to play a key role in the activation and the suppression of the immune response to cancer and are used to treat patients who do not benefit from checkpoint inhibitor therapies.

The company’s drug candidates PY314 and PY159 have shown preclinical efficacy, confirming their potential to treat solid tumours in combination with established anti-PD (L)-1 agents.

PY314 targets TREM2, a protein commonly found on the surface of a certain type of immunosuppressive, pro-tumour myeloid cells, to rebalance the tumour microenvironment for anti-tumour immunity.

PY159 targets TREM1, a protein that is expressed on multiple immunosuppressive myeloid cells such as macrophages, neutrophils and myeloid-derived suppressor cells, to reprogram the immunosuppressive cells to stimulate a pro-inflammatory, anti-tumour immune response.

Pionyr intends to seek investigational new drug (IND) applications with the US Food and Drug Administration for both PY314 and PY159 in the third quarter of 2020.

Pionyr president and CEO Steven P James said: “This agreement underscores the value of our myeloid tuning platform and the potential of our pipeline of antibody therapeutics designed to turbocharge the immune system within the tumour microenvironment.

“PY314 and PY159 are first-in-class antibodies designed to remove or reprogram, respectively, the immune suppressive cells in the tumour microenvironment and thereby enhance anti-tumour immunity.

“We are grateful that Gilead has acknowledged the promise of this transformational approach to potentially benefit patients across a range of solid tumours.”