Plus Therapeutics reaches FDA agreement to initiate ReSPECT-LM trial

Plus Therapeutics (PSTV) announces the initiation of the ReSPECT-LM dose optimization trial for REYOBIQ for the treatment of leptomeningeal metastases. The dose optimization trial follows encouraging results from the Company’s single-dose escalation trial and is designed to evaluate multiple-dose regimens of REYOBIQ administered at defined intervals via intraventricular catheter. The study design is consistent with the FDA’s Project Optimus, and aims to optimize treatment dosing for maximum efficacy and safety. The primary objectives of the trial include determining the safety and tolerability of multiple REYOBIQ doses administered via intraventricular catheter at defined intervals in patients with LM from any primary solid tumor cancer and to identify both the maximum tolerated dose and minimum effective dose. Key additional elements of the trial design include: Enrollment of up to 24 patients, evaluating REYOBIQ administered at the recommended Phase 2 dose or R2PD of 44.1 mCi, fractionated across three dosing intervals, with up to six patients per cohort interval: Cohort 1: 56 days Cohort 2: 28 days Cohort 3a: 14 days Cohort 3b: 14 days The trial will evaluate both safety, pharmacokinetics/dosimetry, and select efficacy-related endpoints such as objective response rate, neurologic progression-free survival, overall survival, changes in neurologic status Furthermore, the trial will analyze cerebrospinal fluid tumor cell counts via Plus’ CNSide CSF assay platform, other pharmacodynamic markers, and compare these to standard CSF cytology Because of the anticipated pace of enrollment, the trial is being limited initially to only two prestigious and high enrolling cancer centers, both in Texas, the University of Texas Health Science Center at San Antonio and the University of Texas Southwestern Medical Center but may expand to more sites if needed.