PURPOSE: Copanlisib in combination with immune checkpoint inhibitors demonstrated synergy and favorable antitumor immune responses in preclinical models. This study evaluated copanlisib plus nivolumab in adults with advanced solid tumors. PATIENTS AND METHODS: In this phase Ib, nonrandomized, open-label, dose-escalation study, patients received intravenous nivolumab 240 mg (day 15 of cycle 1 and days 1 and 15 of subsequent cycles) plus intravenous copanlisib (45 or 60 mg on days 1, 8, and 15 of each cycle) in 28-day cycles. The primary objective was to determine the MTD and/or recommended phase II dose of copanlisib plus nivolumab. Secondary objectives were safety, tolerability, and efficacy. Exploratory objectives included evaluation of potentially predictive biomarkers. RESULTS: Overall, 16 patients were treated [copanlisib: 45 mg (n = 5)
60 mg (n = 11)]. The most common cancer types at baseline were bladder (25.0%) and oropharyngeal (18.8%) cancers. No dose-limiting toxicities were observed
copanlisib 60 mg was deemed the recommended phase II dose in combination with nivolumab 240 mg. Grade 3 and 4 treatment-emergent adverse events were reported in 56.3% and 12.5% of patients, respectively
one grade 5 event was reported (unrelated to treatment). Overall, 18.8% of patients achieved a partial response. Evaluations of potential biomarkers did not correlate with response, but copanlisib-modulated biomarker changes were observed before nivolumab administration and were consistent and dose-dependent. CONCLUSIONS: No new safety concerns were identified with this combination, and preliminary efficacy indicated an antitumor effect. Data supported an immunomodulatory effect of copanlisib, suggesting that this combination may enhance the efficacy of immune checkpoint inhibitors. SIGNIFICANCE: The combination of copanlisib and nivolumab was well tolerated and showed antitumor effects in patients with advanced solid tumors. The number of circulating myeloid-derived suppressive cells decreased 24 to 48 hours after treatment with copanlisib. Further investigation of copanlisib and nivolumab is warranted as a novel strategy to enhance the efficacy of checkpoint inhibitors.