Relay Drug Shows Early Promise against Rare Blood Vessel Diseases

Relay Therapeutics reported early clinical trial results showing its targeted therapy drug shrank tumors in patients with rare blood vessel cancers. The Silicon Review reports on the promising data for malignant peripheral nerve sheath tumors.

Relay Therapeutics announced early clinical trial results showing its targeted therapy drug RLY-2608 demonstrated tumor shrinkage in patients with rare blood vessel cancers known as malignant peripheral nerve sheath tumors. The data was presented at the American Society of Clinical Oncology annual meeting.

The targeted therapy drugs represent a new class of precision medicine that attacks cancer cells with specific genetic mutations while sparing healthy tissue. RLY-2608 is designed to inhibit the PI3K-alpha pathway, which is overactive in approximately 30 percent of MPNST patients.

The new drug clinical trials enrolled 42 patients with advanced MPNST who had failed at least two prior lines of therapy. Results showed that 15 patients, or 36 percent, achieved partial remission with tumor shrinkage of at least 30 percent. Another 18 patients, or 43 percent, achieved stable disease. The median progression-free survival was 7.2 months.

The rare blood vessel disease affects approximately 2,000 new patients annually in the United States. There are currently no FDA-approved therapies specifically for MPNST, with patients typically treated with surgery, radiation, and chemotherapy.

RLY-2608 was generally well tolerated. The most common side effects were nausea, fatigue, and diarrhea, all Grade 1 or 2 in severity. No patients discontinued treatment due to adverse events. Two patients experienced Grade 3 elevated liver enzymes, which resolved with dose interruption.

Relay is planning a pivotal Phase 3 trial for MPNST based on the positive Phase 2 data. The company expects to enroll 120 patients across 30 sites in the United States and Europe starting in the first quarter of 2027. If successful, the drug could receive FDA approval by 2029.

The MPNST program is part of Relay's broader pipeline targeting PI3K-alpha mutations across multiple cancer types. The company is also studying RLY-2608 in breast cancer and other solid tumors.

By the second quarter of 2027, Relay expects to report additional data from an expansion cohort of the MPNST trial, including duration of response data. The company is also exploring combination regimens pairing RLY-2608 with immunotherapy.

The Silicon Review's analysis indicates that the Relay data represents meaningful progress for a disease with no approved targeted therapies. For MPNST patients, who are typically diagnosed in their 30s and 40s, a new treatment option cannot come soon enough.

Q: What is the Relay Therapeutics drug RLY-2608?
A: RLY-2608 is a targeted therapy drug designed to inhibit the PI3K-alpha pathway, which is overactive in approximately 30 percent of malignant peripheral nerve sheath tumor patients.

Q: What were the results of the clinical trial for MPNST patients?
A: Of 42 patients with advanced MPNST, 36 percent achieved partial remission with tumor shrinkage of at least 30 percent, and 43 percent achieved stable disease. Median progression-free survival was 7.2 months.

Q: How many new MPNST patients are diagnosed annually in the United States?
A: Approximately 2,000 new patients are diagnosed with MPNST annually in the United States. There are currently no FDA-approved therapies specifically for this rare cancer.

Q: What were the side effects of RLY-2608?
A: The most common side effects were nausea, fatigue, and diarrhea, all Grade 1 or 2 in severity. No patients discontinued treatment due to adverse events.

Q: When will Relay Therapeutics start the Phase 3 trial for MPNST?
A: Relay expects to enroll 120 patients across 30 sites in the United States and Europe starting in the first quarter of 2027.

Q: When could RLY-2608 receive FDA approval if the Phase 3 trial is successful?
A: If the Phase 3 trial is successful, the drug could receive FDA approval by 2029.