LMAP-21 PRELIMINARY CLINICAL DATA IN THE PHASE 1/2A DOSE ESCALATION TRIAL OF RHENIUM (186RE) OBISBEMEDA (186RNL) IN LEPTOMENINGEAL METASTASES (LM): THE RESPECT-LM TRIAL

Abstract OBJECTIVES Leptomeningeal metastases (LM) are an increasing complication of metastatic cancer with limited treatment options and poor survival. 186RNL is BMEDA-chelated 186Re encapsulated in nanoliposomes. 186Re’s ~2 mm beta emission path length provides direct delivery radiation therapy while sparing surrounding healthy tissue. A Phase I dose escalation safety efficacy study (ReSPECT-LM, NCT05034497) current enrolling. METHODS ReSPECT-LM a multi-center, sequential cohort, open-label, dose-escalation, 1/2a clinical trial adults evaluating the safety, tolerability, activity single given via Ommaya reservoir. The primary objectives maximum tolerated dose, progression, Using modified 3x3 Fibonacci design, doses were administered 5 mL followed by whole body planar SPECT/CT imaging for dosimetry distribution. CSF tumor cell count/mL using microfluidic chamber assay was assessed up to 56 days. RESULTS total 7 LM patients have been treated (3 male, 4 female) oropharyngeal, breast, lung cancer. One patient twice (retreatment). showed prompt, complete distribution throughout durable retention subarachnoid space leptomeninges. Absorbed ≥20 Gy ventricles cranial spaces measured. In positive cells, decrease counts ranging from 50-92% observed. Six remain alive, 1 has died due progression. No had related adverse events (AEs) greater than Grade 1, most common AE headache. CONCLUSION Preliminary, interim results this ongoing that delivered intraventricular catheter well tolerated, without limiting toxicity decreased through at least 30 Enrollment continuing, repeated dosing will be further explored.