Plus Therapeutics completed its Phase 1 single-dose escalation trial of Rhenium (¹⁸⁶Re) Obisbemeda, administered intrathecally, for patients with leptomeningeal metastases (LM), identifying a recommended Phase 2 dose (RP2D). The RP2D of 44.1 mCi was determined based on safety and tolerability, with one patient at this dose level achieving a complete response indicated by the elimination of cerebrospinal fluid tumor cells. The company now plans to initiate both a single dose-expansion Phase 2 trial and a multiple-dose Phase 1 trial using the established RP2D.
This development is particularly promising for LM patients, a population with limited treatment options and a grim prognosis. Current treatments often struggle to effectively penetrate the cerebrospinal fluid, leaving tumor cells untouched. The observed complete response in a patient treated with Rhenium (¹⁸⁶Re) Obisbemeda suggests a potential for this radiotherapeutic to reach and eliminate these otherwise inaccessible cancer cells, offering a new avenue for treating this devastating complication.
The Phase 1 trial evaluated the safety, tolerability, and preliminary efficacy of the treatment across escalating dose cohorts, culminating in the identification of the 44.1 mCi RP2D. Notably, no dose-limiting toxicities were observed at this dose level. The company aims to complete enrollment in both the Phase 2 single-dose expansion trial and the Phase 1 multiple-dose trial within the year and is working with the FDA to determine the most effective pathway for a pivotal trial.
The completion of the Phase 1 trial and the establishment of an RP2D represent a crucial step towards potentially providing a much-needed effective treatment for LM. The upcoming trials will be instrumental in further validating the efficacy and safety of Rhenium (¹⁸⁶Re) Obisbemeda, potentially paving the way for a new standard of care for patients with LM and offering a renewed hope for improved survival outcomes.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
