Salarius hits pause on enrollment of lead sarcoma asset trial after patient death

Salarius Pharmaceuticals has paused enrollment on a phase 1/2 trial of its lead candidate following the death of a patient.

The trial of the therapy, called seclidemstat, was assessing its use on patients with Ewing sarcoma—or similar types of sarcomas—a cancer that forms in the bone or connective tissues. One of the patients with the latter form of the cancer died during the trial, with the death classified as a so-called suspected unexpected serious adverse reaction (SUSAR), the biotech said.

The company has already communicated the details of the death to the FDA and intends to further analyze the data so it can understand how best to proceed and ideally restart enrollment as soon as possible.

Patients already enrolled in the trial can continue to receive the therapy after consulting their physician, said the company, which plans to release more data from the trial as planned later this year.

“Patient safety is our primary concern, and this is reflected in the design of our clinical trial protocol, which automatically paused enrollment based upon this SUSAR,” Salarius CEO David Arthur said in the release Tuesday. “Unfortunately, pauses to enrollment occur in early-stage drug development, but these pauses allow time to understand new data and adjust clinical protocols and development plans as needed.”

The three-arm trial aims to recruit 30 patients with Ewing sarcoma, a rare and deadly pediatric bone cancer, who are receiving seclidemstat in combination with chemotherapy. The trial’s second and third arms will each consist of a cohorts of 15 patients receiving seclidemstat as a single agent. One of these groups is comprised of patients with myxoid liposarcoma, which affects fat cells, while the other have select sarcomas that share a similar biology to Ewing sarcoma, known as FET-rearranged sarcomas.

Seclidemstat is a differentiated inhibitor of the LSD1 enzyme that has received fast-track, orphan-drug and rare pediatric disease designations from the FDA. In addition to sarcoma, Salarius is also exploring the therapy’s potential in several cancers with high unmet medical need, including an investigator-initiated phase 1/2 study in hematologic cancers at MD Anderson Cancer Center.

The only other asset in Salarius’ pipeline is SP-3164, an oral, small-molecule protein degrader designed to degrade oncoproteins implicated in hematological and solid tumors. SP-3164 is expected to enter the clinic in 2023.

Salarius’ shares were trading down a hefty 20% at $3.91 in premarket trading on Tuesday morning.