Spyryx Biosciences Launches Phase 1b Study of Potential CF Therapy SPX-101

Spyryx Biosciences has marked Feb. 28, Rare Disease Day, by announcing it will initiate a Phase 1b study to assess the safety of its SPX-101 in cystic fibrosis (CF) patients.

SPX-101 is an experimental peptide designed to block the function of the lungs’ sodium channels, which move sodium and water from the airway surface. Blocking these channels may help maintain fluid within the airways, improving the clearing of mucus in patients with CF — a disease characterized by dehydration of fluid on the airway surface.

SPX-101’s mechanism of action is independent of the genetic mutations that cause CF, which is why this therapy may potentially benefit all CF patients, says Spyryx.

“This Phase 1b study is an important final step as we move into a full-fledged Phase 2 study with cystic fibrosis patients,” Alistair Wheeler, MD, the company’s chief medical officer, said in a press release. “Having completed the study in healthy subjects and found SPX-101 to be safe and well tolerated, we look forward to advancing into patients and further evaluating this novel and exciting peptide. It is fitting on Rare Disease Day that we are able to share our progress in bringing a new potential treatment to these patients.”

Planning for the Phase 1b trial (NCT03056989) comes after a successful Phase 1 trial evaluating the safety, tolerability and pharmacokinetics of SPX-101. The drug was well tolerated in all 64 participants, and all subjects completed the study protocol.

Researchers found no adverse effects on lung function, no shifts in serum or urinary electrolytes, and no evidence of hyperkalemia (high serum potassium concentration). The peptide behaved as expected, with very low systemic exposure and rapid clearance from the circulation.

“With the absence of dose-limiting adverse effects in healthy adults, we are anticipating a similar result in cystic fibrosis patients,” Wheeler said. “Combined with the strong scientific rationale for a meaningful effect on pulmonary function, we are eager to move the program into the CF patient population in Phase 2.”

The Phase 2 trial will be a 28-day, adaptive-design study of multiple SPX-101 doses in up to 80 CF patients. The trial will evaluate the safety, tolerability and efficacy of SPX-101, as well as lung function changes and quality of life improvements in CF patients, regardless of their genetic mutation.