3040 Background: BAY 57–9352 is a potent competitive inhibitor of the VEGFR-2 (IC50: 6 nM), VEGFR-3 (IC50: 4 nM), PDGFR-β and c-KIT tyrosine kinases. BAY 57–9352 showed tumor efficacy in colon, breast, pancreatic and NSCLC models. Methods: Patients with advanced solid tumors received oral BAY 57–9352 on a continuous basis, in escalating doses. One cycle was defined as 21 days of treatment. Extensive PK and PD (dynamic contrast-enhanced MRI [DCE-MRI]) evaluations were performed. Plasma biomarkers (e.g. VEGF)were also evaluated. Results: Forty patients (median 54 yrs) were enrolled at seven dose levels from 20 mg solution once daily to1500 mg twice daily (bid; 150 mg tablets) for a total of 169 cycles (range 1–17). The most frequent drug-related adverse events were nausea, hypertension, headache, vomiting, hoarseness, rash, dry skin and anorexia. One patient treated at 600 mg bid had a dose-limiting toxicity defined by an increase from grade 2 to 3 hypertension, despite the addition of an ACE-inhibitor and Ca-antagonist on day 8 of cycle 2. Another patient at that same dose level and also on day 8 cycle 2, had grade 3 AST/ALT increase, however this was not assessed as dose-limiting. Both patients continued treatment after dose reductions. Treatment was well tolerated, even at the highest dose levels. One patient with a hemangio-endothelioma (600 mg bid) had a clinical response and one desmoid tumor patient (900 mg bid) had a 53% reduction in tumor volume. BAY 57–9352 AUC increased dose proportionally up to 900 mg bid. The target AUC, based on animal models (5 mg × h/L) was reached in all patients at 900 mg bid. Dose levels exceeding 900 mg bid had similar plasma VEGF biomarker levels. Conclusions: BAY 57–9352 was well tolerated in doses up to 1500 mg bid. Based on safety, PK, PD and biomarker assessments, the recommended dose level is 900 mg bid. A 300 mg tablet is being tested for patient convenience. Combination chemotherapy studies have been started. [Table: see text]