Background: Volasertib (V) is a potent and selective cell cycle kinase inhibitor that induces mitotic arrest and apoptosis by targeting Polo-like kinases. Nintedanib (N) is a triple angiokinase inhibitor of VEGF, PDGF, and FGF receptors. Both have shown clinical activity with a manageable safety profile in patients (pts) with advanced solid tumors. This study was designed to determine the maximum tolerated dose (MTD) of V combined with N in these pts. Methods: Cohorts of 3–6 pts received V (100–450 mg IV Q3W) + oral standard dose N (200 mg BID continuously, except V infusion day). Treatment continued until clinical progression. Up to 12 pts were treated at the MTD for additional safety data. Primary endpoint was the MTD; secondary endpoints were pharmacokinetics (PK), overall safety, and preliminary efficacy. Results: 30 pts were treated (median age, 56.5 yr; ECOG PS 0/1/2, 33%/60%/7%; ≥3 prior therapies, 87%). At V doses >200 mg, 7 pts experienced 13 dose-limiting toxicities (DLTs) during cycle 1: increased alanine aminotransferase [ALT] or aspartate aminotransferase [AST], neutropenia and thrombocytopenia. The MTD was V 300 mg (Table). At the MTD, the most common all grade (Gr) adverse events (AEs) were neutropenia (69%), asthenia and thrombocytopenia (62% each), increased ALT, increased AST and diarrhea (54% each). Median (range) duration on treatment was 4 (1–18) cycles. Treatment was discontinued due to progressive disease (80%), DLT (3%) and other non-AE related reasons (17%). 2 objective responses were observed (1 complete [breast cancer] and 1 partial [NSCLC]), both with the 300 mg dose. 6 pts had SD for ≥ 6 mo. PK data will be presented at the meeting. Conclusions: MTD of V + standard dose N (200 mg BID) was determined to be 300 mg Q3W (the same as the recommended phase II single agent dose of V in solid tumors). This combination had a manageable safety profile without unexpected or overlapping toxicities and showed preliminary antitumor activity. Clinical trial information: NCT01022853.