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# Orphan Status for Breast Cancer Radiotherapy
- URL: https://www.fdaweb.com/orphan-status-for-breast-cancer-radiotherapy/
- Published: 2023-11-06T12:00:00.000Z
- Updated: 2026-09-14T14:15:22.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5155722

FDA has granted Plus Therapeutics an orphan drug designation for rhenium obisbemeda, an injectable radiotherapy for treating breast cancer with leptomeningeal metastases (LM). The therapy is currently being evaluated in the ReSPECT-LM Phase 1/2a dose escalation clinical trial. FDA previously granted rhenium obisbemeda a fast track designation for treating LM.

Plus describes LM as a rare complication of cancer in which the primary cancer spreads to the cerebrospinal fluid (CSF) and leptomeninges surrounding the brain and spinal cord. “All malignancies originating from solid tumors, primary brain tumors, or hematological malignancies have this LM complication potential with breast cancer as the most common cancer linked to LM, with 3-5% of breast cancer patients developing LM,” it says. “Additionally, lung cancer, GI cancers and melanoma can also spread to the CSF and result in LM.”

Rhenium obisbemeda is a novel injectable radiotherapy formulated to deliver highly targeted high-dose radiation in CNS tumors, the company says. It is believed to be an “ideal radioisotope for CNS therapeutic applications due to its short half-life, beta energy for destroying cancerous tissue and gamma energy for live imaging,” it adds.