The SRF617 program

About the target
CD39 is an enzyme critical to both the production of adenosine and the breakdown of adenosine triphosphate (ATP). The accumulation of adenosine leads to immunosuppression, whereas maintained levels of ATP increases T cell proliferation, dendritic cell maturation and pro-inflammatory cytokine levels.

About our antibody candidate
SRF617 is a fully human antibody designed to inhibit the enzymatic activity of CD39 in the tumor microenvironment, allowing for a dual mechanism of action to promote anti-tumor immunity via reduction of immunosuppressive adenosine in addition to increasing levels of immunostimulatory ATP. A substantial body of research supports a role for CD39 in allowing cancer to evade immune responses. For example, pancreatic cancer stromal cells within the tumor micro-environment express high levels of CD39 which may inhibit anti-cancer immune responses. In preclinical studies, SRF617 has exhibited strong affinity for and inhibition of CD39, the ability to reduce adenosine and increase ATP levels and anti-tumor activity both as a single agent and in combination with multiple therapeutic agents.

Clinical trial information
The first-in-human study in patients with advanced solid tumors is enrolling in multiple cohorts including SRF617 monotherapy, SRF617 in combination with gemcitabine and albumin-bound paclitaxel (ABRAXANE®), and SRF617 in combination with Merck’s KEYTRUDA® (pembrolizumab).  Additional combination therapy expansion arms are planned. Further planned cohorts will focus on several tumors of high unmet need, including pancreatic cancer, gastric cancer and tumors that have demonstrated resistance to anti-PD-1 therapy. A biopsy expansion cohort has been designed to provide data on changes in tumor tissue CD39 enzymatic activity related to SRF617 treatment. For more information about our clinical trials, visit

Compassionate Use Statement
Expanded access, or compassionate use, is the use of an investigational medicine prior to regulatory approval and outside of a clinical trial.

Surface Oncology does not currently have an expanded access program or compassionate use program for any of our investigational products.

We understand that for patients with serious diseases such as cancer, waiting for an approved treatment can be difficult. We believe that devoting ourselves to current and future clinical trial programs provides the best path to meet our goal of providing therapeutics to patients with cancer.

We encourage you to speak with your physician about options that may be right for you.