Surface Oncology Pauses CD39 Program, Slashes Workforce by 20%


Massachusetts-based Surface Oncology will pause the development of its CD39-targeted antibody SRF617 and cut around 20% of its workforce to focus on its lead anti-IL-27 program SRF388, the company announced Wednesday.

In an investor call, Robert Ross, M.D., CEO of Surface, emphasized that the company continues to believe in its anti-CD39 candidate. Ross called the decision to pause the development of SRF617 "a strategic business decision," adding that it "certainly is not a reflection of the outstanding work our team has done advancing this molecule."

“We continue to believe that SRF617 holds therapeutic potential in a variety of tumor types in combination with other agents," Ross said. "However, we believe it is in the best interest of patients and our shareholders to invest our finite resources where they can have the greatest potential impact in the near-term.”

Surface is actively looking for business development opportunities for SRF617.

These strategic decisions come after a portfolio review and a string of promising efficacy signals for SRF388. An ongoing study in non-small cell lung cancer (NSCLC) has confirmed two cases of partial response after monotherapy with the anti-IL-27 antibody. 

Meanwhile, a third patient showed durable disease stabilization that lasted for over 56 weeks. All three patients showing promising clinical data had previously been treated with anti-PD-(L)1 agents.

Based on these findings, Surface has decided to proceed to the second stage of the trial. The company has also started a single-arm Phase II study to assess SRF388 in combination with Merck’s Keytruda (pembrolizumab) in NSCLC.

Data from ongoing SRF388 are expected to start rolling in the first half of next year. During the call, Ross said the company will be "very well-positioned" for regulatory discussions about a registration trial in NSCLC in the next 12-18 months. 

SRF388 is a fully human antibody designed to bind and target the immunosuppressive cytokine IL-27, which works to help ease T cell-mediated inflammation. In its studies, Surfaces identified specific types of cancer where IL-27 contributes to resistance to checkpoint inhibitors.

Surface has also found markers that could identify patients who are likely to respond to SRF388 treatment. According to the company, SRF388 is the first IL-27 antibody to enter clinical studies.

To focus its resources on SRF388 and NSCLC, Surface has decided to suspend enrollment for studies in renal cell carcinoma. In addition, this strategic realignment will help fund Surface into the second quarter of 2024.

Like SRF388, SRF617 is a fully human antibody that targets CD39, an enzyme important for the production of adenosine and the breakdown of ATP. Through this action, SRF617 triggers a two-pronged attack against cancer: lowering the concentrations of the immunosuppressive adenosine in the tumor microenvironment, while elevating levels of the immunostimulatory ATP.

Aside from SRF388, Surface is retaining SRF114, its CCR8-targeted antibody with potential best-in-class performance. The FDA cleared SRF114’s Investigational New Drug application earlier this month, and the company expects to enroll its first patient soon.

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