Clinical-stage pharmaceutical company Plus Therapeutics Inc (Nasdaq:PSTV) announced on Thursday that the US Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to Rhenium (186Re) Obisbemeda for treating leptomeningeal metastases (LM) in lung cancer patients.

LM is a rare and fatal cancer complication where tumour cells spread to the cerebrospinal fluid and leptomeninges surrounding the brain and spinal cord. It affects approximately 5% of cancer patients, with survival rates of 7% at one year and 3% at two years. There are currently no FDA-approved treatments for LM.

Rhenium (186Re) Obisbemeda is an injectable radiotherapy designed to deliver targeted radiation to central nervous system tumours.

The FDA's ODD status provides Plus Therapeutics with incentives such as potential seven-year market exclusivity, tax credits for clinical trials, and regulatory fee exemptions.

This designation follows completion of the ReSPECT-LM Phase 1 trial, which established the recommended Phase 2 dose. Plus Therapeutics is advancing Phase 2 and Phase 1 multiple-dose trials and working with the FDA on a pivotal trial strategy.