Feb 9, 2020

Low-Dose Rapamycin Prevents Progression in Men With Prostate Cancer Under Active Surveillance

By Ed Susman

ORLANDO, Fla -- February 9, 2020 -- Low-dose rapamycin (sirolimus) may safely prevent disease progression in men with intermediate grade prostate cancer who are under active surveillance, according to a study presented here at the 2020 Clinical Immuno-Oncology Symposium.

“No patient demonstrated clinical evidence of disease progression during the 6-month trial,” said Philip Kemp Bohan, MD, Brooke Army Medical Center, San Antonio, Texas.

For the study, 15 men aged 65 to 69 years with prostate cancer (Gleason score, 6-7) received encapsulated rapamycin 0.5 mg once a week, rapamycin 1 mg per week, or rapamycin 0.5 mg/day for 3 months. Patients were followed-up for another 3 months after treatment ended.

The trial used polymer capsules of rapamycin, which “improves the bioavailability of the drug and allows for a more sustained, predictable flow of the drug,” said Dr. Bohan.

“We are trying to show that we can give these patients a low dose of the drug to try to get an immune response against the cancer,” he said. “No medical therapies have been shown to reliably and safely decrease low-grade disease progression.”

The key, he noted, is to accomplish treatment without adverse events. In the study, the only dose-limiting toxicity was observed in 1 man receiving rapamycin daily. He developed grade 3 neutropenia and discontinued the study. Two other patients also discontinued the study, but not due to toxicities. All other adverse events in the 2 lower doses were grade 1.

Dr. Bohan said that the pharmacokinetics showed that treatment with the encapsulated rapamycin produced a consistent trough level of the drug. The low-dose encapsulated oral medication is not available commercially at this time.

The 2020 Clinical Immuno-Oncology Symposium is co-sponsored by the American Society of Clinical Oncology (ASCO) and the Society for Immunotherapy of Cancer (SITC).

[Presentation title: Results of a Phase Ib Trial of Encapsulated Rapamycin in Prostate Cancer Patients Under Active Surveillance to Prevent Progression. Abstract 34]

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