A first-in-human phase I study of oral pan-CDK inhibitor BAY 1000394 in patients with advanced solid tumors: Dose escalation with an intermittent 3 days on/4 days off schedule.
3012 Background: BAY 1000394 (BAY) is an oral pan-CDK inhibitor targeting CDKs 1,2,4, 7 and 9 in the low nanomolar range. A phase I dose escalation study was initiated to determine the maximum tolerated dose (MTD), pharmacokinetics (PK), and pharmacodynamics (PD) in patients (pts) with advanced solid tumors. Methods: BAY was administered twice daily in a 3 days on / 4 days off schedule (cycle length 21 days, 3+3 design). PK was evaluated on cycle 1 day 1 and day 10. Response rate was assessed according to RECIST 1.1. PD markers included CK18 fragments in plasma. Results: As of Jan 08 2011, 34 pts were treated at doses of 0.6 (3 pts), 1.2 (4), 2.4 (3), 4.8 (3), 9.6 (3), 19.2 (6) mg per day as oral solution and at doses of 10 (4), 15 (6) and 20 (2) mg per day as tablet. Tumor types included 10 colorectal, 4 mesothelioma and 20 others. Cohort 9 (20 mg tablet) is ongoing. Frequent CTCAEv4 grade 1/2 drug related AEs occurring in more than 25% of patients up to cohort 8 were asthenia, diarrhea, nausea, vomiting and anorexia. DLTs (grade 3, 1 pt each) were hyponatremia, aphtous stomatitis at 19.2 mg solution and arterial thrombosis at 15 mg tablet. Aphthous stomatitis (20%) has not been observed with the tablet formulation. Other grade 3 related AEs were asthenia in 2 and nausea and vomiting in one pt each. Nausea and vomiting on treatment days were observed despite antiemetic treatment (aprepitant +/- setron). PK was dose proportional up to 9.6 mg, T1/2 was 10 hours, and relative bioavailability of tablet formulation was excellent; major metabolite levels were low (<10%). Levels of CK18 fragments did not correlate with dose or tumor response. Stable disease (SD) lasting for 2-4 months was observed in 9 patients, among others in 4 of 4 mesothelioma and 2 of 2 ovarian pts. One additional pt with cholangiocarcinoma has ongoing SD lasting for 5 months. One of the ovarian pts had a significant decline of CA125 lasting for 3 months. Conclusions: The tablet formulation of BAY 1000394 was better tolerated than oral solution. So far, doses up to a 15 mg per day with concomitant antiemetic treatment showed an acceptable tolerability. SD was observed in 10 of 25 heavily pretreated pts across cohorts 3 – 8.