A phase I clinical and pharmacokinetic study of oral CI-1033 in combination with docetaxel in patients with advanced solid tumors.

PURPOSE CI-1033 is an orally available 4-anilinoquinazolone irreversible tyrosine kinase inhibitor of erbB-1, erbB-2, and erbB-4. We conducted a dose escalation study of CI-1033 with docetaxel to assess the safety profile and pharmacokinetics of the combination and to establish the maximum tolerated dose. EXPERIMENTAL DESIGN Twenty-six patients with advanced solid tumors were treated on four dosing cohorts starting at CI-1033 (50 mg/d) + docetaxel (75 mg/m2). An intermittent dosing schedule avoided concurrent drug dosing. RESULTS CI-1033 alone was escalated from 50 to 75 mg/d (dose level 2), where diarrhea was dose limiting; a 38% incidence of cycle 1 febrile neutropenia prompted dose de-escalation of both CI-1033 and docetaxel for dose level 3, where dose-limiting toxicities prompted further de-escalation of CI-1033 to 45 mg/d. Given equivalent safety profiles for dose level 1 [CI-1033 (50 mg/d) + docetaxel (75 mg/m2)] and dose level 4 [CI-1033 (45 mg/d) + docetaxel (60 mg/m2)], the former was determined to be the recommended phase II dose, given greater dose intensity of both drugs. Antitumor activity was noted in three patients, including a complete response in a patient with cervix uteri cancer. Pharmacokinetic analysis showed a possible effect of docetaxel on CI-1033 pharmacokinetics. CONCLUSIONS It is feasible to combine the irreversible pan-erbB tyrosine kinase inhibitor CI-1033 with docetaxel on an intermittent dosing schedule in advanced cancer patients. We established the maximum tolerated dose and recommended phase II dose for the combination. Further investigation of this combination should include a rigorous analysis of the effect of docetaxel on CI-1033 pharmacokinetics.