Phase 1 lead‐in to a phase 2 factorial study of temozolomide plus memantine, mefloquine, and metformin as postradiation adjuvant therapy for newly diagnosed glioblastoma

<jats:sec><jats:title>Background</jats:title><jats:p>Repurposed memantine, mefloquine, and metformin have putative anticancer activity. The objective of this phase 1 study was to determine the maximum tolerated doses (MTDs) of combinations of these agents with temozolomide (TMZ).</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Adults with newly diagnosed glioblastoma who completed chemoradiation were eligible. The patients were assigned to receive doublet, triplet, or quadruplet therapy with TMZ combined with mefloquine, memantine, and/or metformin. Dose‐limiting toxicities (DLTs) were determined, using a 3 + 3 study design.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Of 85 enrolled patients, 4 did not complete cycle 1 (the DLT observation period) for nontoxicity reasons, and 81 were evaluable for DLT. The MTDs for doublet therapy were memantine 20 mg twice daily, mefloquine 250 mg 3 times weekly, and metformin 850 mg twice daily. For triplet therapy, the MTDs were memantine 10 mg twice daily, mefloquine 250 mg 3 times weekly, and metformin 850 mg twice daily. For quadruplet therapy, the MTDs were memantine 10 mg twice daily, mefloquine 250 mg 3 times weekly, and metformin 500 mg twice daily. DLTs included dizziness (memantine) and gastrointestinal effects (metformin). Lymphopenia was the most common adverse event (66%). From study entry, the median survival was 21 months, and the 2‐year survival rate was 43%.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Memantine, mefloquine, and metformin can be combined safely with TMZ in patients with newly diagnosed glioblastoma.</jats:p></jats:sec>