HOUSTON, March 06, 2025 — Plus Therapeutics, Inc. (NASDAQ: PSTV) (the “Company” or “Plus Therapeutics”), a clinical-stage pharmaceutical company developing targeted radiotherapeutics with advanced platform technologies for central nervous system cancers, today announces that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to Rhenium (186Re) Obisbemeda for the treatment of leptomeningeal metastases (LM) in patients with lung cancer.
“Receiving Orphan Drug Designation for Rhenium (186Re) Obisbemeda marks a significant milestone in our efforts to develop a much-needed therapy for lung cancer patients with leptomeningeal metastases,” said Mike Rosol, Ph.D., Plus Therapeutics Chief Development Officer. “These patients currently have limited treatment options, and the growing incidence of LM in lung cancer underscores the urgency for new therapies. This designation, in combination with our previously granted Fast Track designation, strengthens our pathway toward delivering an innovative, targeted radiotherapeutic solution for this highly underserved patient population.”
The FDA grants ODD status to an investigational drug or biologic intended to prevent, diagnose, or treat a rare disease or condition affecting fewer than 200,000 people in the United States. ODD provides certain benefits to drug developers, including seven potential years of market exclusivity, tax credits for qualified clinical trials, and exemptions from significant regulatory fees, including the Prescription Drug User Fee Act (PDUFA) charge of $4.3 million in 2025 and the Pediatric Research Equity Act (PREA) requirements.
This milestone follows the recent completion of the ReSPECT-LM Phase 1 single-dose trial, which established the recommended Phase 2 dose (RP2D). The Company is now advancing a Phase 2 single-dose expansion trial and a Phase 1 multiple-dose trial while actively engaging the FDA to define the optimal pivotal trial strategy.
Additional details on the ReSPECT-LM trial can be found here.
About Leptomeningeal Metastases (LM)
LM is 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. Additionally, lung cancer, GI cancers and melanoma can also spread to the CSF and result in LM. LM occurs in approximately 5% of people with cancer and is usually terminal with 1-year and 2-year survival of just 7% and 3%, respectively. The incidence of LM is on the rise, partly because cancer patients are living longer and partly because many standard chemotherapies cannot reach sufficient concentrations in the spinal fluid to kill the tumor cells, yet there are no FDA-approved therapies specifically for LM patients, who often succumb to this complication within weeks to several months, if untreated.
About Rhenium (186Re) obisbemeda
Rhenium (186Re) obisbemeda is a novel injectable radiotherapy specifically formulated to deliver highly targeted high dose radiation in CNS tumors in a safe, effective and convenient manner to optimize patient outcomes. Rhenium (186Re) obisbemeda has the potential to reduce risks and improve outcomes for CNS cancer patients, versus currently approved therapies, with a more targeted and potent radiation dose. Rhenium-186 is 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. Rhenium (186Re) obisbemeda is being evaluated for the treatment of recurrent glioblastoma and leptomeningeal metastases in the ReSPECT-GBM and ReSPECT-LM clinical trials. ReSPECT-GBM is supported by an award from the National Cancer Institute (NCI), part of the U.S. National Institutes of Health (NIH), and ReSPECT-LM is funded by a three-year $17.6M grant by the Cancer Prevention & Research Institute of Texas (CPRIT).
About Plus Therapeutics
Plus Therapeutics, Inc. is a clinical-stage pharmaceutical company developing targeted radiotherapeutics for difficult-to-treat cancers of the central nervous system with the potential to enhance clinical outcomes for patients. Combining image-guided local beta radiation and targeted drug delivery approaches, the Company is advancing a pipeline of product candidates with lead programs in recurrent glioblastoma (GBM) and LM. The Company has built a supply chain through strategic partnerships that enable the development, manufacturing and future potential commercialization of its products. Plus Therapeutics is led by an experienced and dedicated leadership team and has operations in key cancer clinical development hubs, including Austin and San Antonio, Texas. For more information, visit https://plustherapeutics.com/.