The cyclin-dependent kinase inhibitor UCN-01 plus cisplatin in advanced solid tumors: A California cancer consortium phase I pharmacokinetic and molecular correlative trial

Background: UCN-01 (7-hydroxy-staurosporine) is a novel antineoplastic agent targeting cyclin-dependent kinases, which shows potent in vitro and in vivo activity against a broad range of tumor types. Our group has previously shown that UCN-01 potentiates the apoptotic response of agents such as cisplatin in vitro by preventing sequence-specific abrogation of G(2) arrest caused by DNA-damaging chemotherapies. Patients and Methods: This National Cancer Institute-sponsored phase I trial was designed to determine the safety, maximum tolerated dose, and pharmacokinetics of escalating doses of cisplatin in combination with UCN-01 in patients with advanced malignant solid tumors, as well as to do molecular correlative studies on tumor specimens. Cisplatin was infused over 1 hour before UCN-01 (45 mg/m(2)/d) given as a 72-hour continuous infusion. Escalation of cisplatin was planned through five dose levels at 20, 30, 45, 60, and 75 mg/m(2). Results: Ten patients were accrued. Accrual was halted at dose level 2 (cisplatin, 30 mg/m(2)) due to dose-limiting toxicities consisting of grade 5 sepsis with respiratory failure associated with grade 3 creatinine (one patient) and grade 3 atrial fibrillation (one patient). Plasma and salivary pharmacokinetics of UCN-01 were unaffected by cisplatin. Pretreatment and post-treatment tumor biopsies showed that UCN-01 was active against a key molecular target, the checkpoint kinase Chk1. Conclusions: This phase I trial failed to achieve targeted therapeutic dose levels of cisplatin when combined with prolonged infusion UCN-01. However, because preclinical data indicate that UCN-01 potentiates response to platinum, further studies with alternative dose schedules of the combination, or with other platinum analogues, are warranted.