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Safety Signal Prompts Surface Oncology to Scale Down Lead Program

Xconomy Boston — 

Signs of a safety problem have Surface Oncology cutting back clinical trial plans for its lead drug only eight months after the company completed a $108 million IPO to finance clinical tests of the drug.

The discovery of potential toxic effects of the drug, SRF231, in the dose-escalation portion of a Phase 1 study has led Surface (NASDAQ: SURF) to “significantly reduce” plans for its lead candidate and turn its attention to two others, the company said after the market close Tuesday.

Shares of Surface dipped more than 16 percent in after-hours trading following the announcement.

Surface developed SRF231 to block a protein, CD47, that is overabundant on the surface of tumors. The Phase 1 study was expected to enroll up to 48 patients who have advanced solid tumors or blood cancers. Surface had tested its drug in 18 patients to date, each given a dose every three weeks. The company said dose-limiting side effects were observed in two patients and were resolved. But the company added that these effects were seen in lower-than-expected doses.

The safety signal, combined with competition from other drugs targeting the same protein, were factors in deciding to scale back work on SRF231, CEO Jeff Goater said in a prepared statement. The company said it will explore additional dosing schedules for the drug but will not expand the study as planned. Surface expects to present more data about the drug in the second half of 2019.

In the meantime, Surface will turn its attention to two preclinical programs. The company said it will speed up plans to apply for authorization to start clinical tests of SRF388, a drug developed to target a protein called IL-27. An application for a clinical trial testing SRF617, which targets the CD39 protein, is on track for the fourth quarter of 2019, Surface said. The company estimated its cash holdings will total $160 million at the end of this year.

Image by the National Cancer Institute