ABSTRACT: Abstract BACKGROUND Saposin C-dioleylphosphatidylserine (SapC-DOPS) is a novel blood-brain barrier penetrant nanoliposomal agent that targets externalized phosphatidylserine overexpressed on tumor cell membranes. A recent Phase 1a BXQ-350 trial (NCT02859857) reported SapC-DOPS was well tolerated in both solid tumor and high-grade glioma (HGG) patients with potential for treating clinically challenging gliomas, including their diffuse infiltrative components. METHODS We evaluated the HGG subset of the ongoing Phase 1 study of IV BXQ-350 administered on Days 1–5, 8, 10, 12, 15, 22 (cycle 1) and each 28 day cycles thereafter. MRI neuroimaging (e.g. Axial T1-post-contrast Ax SE T1 POST-FC and medically necessary views) at Days 29, 57, 113, and 171 (or withdrawal) were completed. RANO assessment, functional neurological deficits, ECOG Performance Status, and safety were assessed. RESULTS The HGG patients (9/17) were dosed at 0.7 (N = 1), 1.1 (N = 1), 1.4 (N = 2), 1.8 (N = 2), or 2.4 (N = 3) mg/kg, with 8/9 completing a full cycle before withdrawal (7 due to progression, 1 voluntary withdrawal). BXQ-350 was not linked to dose limiting toxicities or severe adverse reactions. Functional neurological deficits and ECOG decline were proportional to radiological progression, with ECOG scores declining from a baseline 0–1 in 2/9 (22%) to 3. One patient completing 6 cycles (>12 months) of BXQ-350 therapy (0.7 mg/kg) exhibited stable disease, -7% lesion size, and no significant progressive functional neurological deficits. Three patients underwent surgery for progression while on treatment. CONCLUSIONS: BXQ-350 was well tolerated by GBM patients with promising best response apparent in neuroimaging, suggesting therapeutic benefit warranting further trials. Updates from the ongoing trial will be presented.
