2073 Background: ZK304709 is a novel MTGI that selectively inhibits activity of Cyclin Dependent Kinases (CDKs) 1, 2, 4, 7, 9, and the tyrosine kinase activity of VEGF-R 1, 2, 3 and PDGF-βR. Methods: Adult patients (pts) with a good performance status (WHO PS ≤2) and a histologically or cytologically confirmed relapsed/refractory solid tumor were eligible. ZK304709 is administered, as a monotherapy, orally on days 1–7 of a 21-day cycle to fasting patients at a starting dose of 15 mg qd. Dose escalation has ranged from 33% - 100% of prior dose, depending on occurrence of drug-related toxicity ≥ grade (gr) 2 (CTC v2.0). Between 3 and 7 patients are to be enrolled per dose level, depending on DLTs that are observed. The primary objective is determination of the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT) of ZK304709. Secondary objectives include tolerability, pharmacokinetic (PK) profile, and preliminary efficacy. Results: Interim results are available for 22 pts (15 M/7 F, median age 60.5 yrs; range 37–71) treated with ZK304709 at 6 dose levels (15 - 180 mg qd). Patients completed a median of 2 cycles (range 0–8). Common AEs were nausea, vomiting, diarrhea, and lethargy. Two DLT were observed: supraventricular tachycardia and vomiting, but the MTD was not reached. The PK profile shows rapid absorption, with a Tmax of 2–4 hrs, and a dose-dependent increase in systemic exposure over the 15–90 mg dose range. Disease stabilization for ≥4 cycles has been observed. Conclusions: ZK304709 is rapidly absorbed and has been tolerated on this schedule at doses up to 180 mg qd. The MTD has not been reached, and enrolment is ongoing. These preliminary data demonstrate that oral delivery on this schedule of an agent that inhibits both cell cycle and angiogenesis is feasible. [Table: see text]