Karen Small

Dinaciclib is a Novel Cyclin Dependent Kinase Inhibitor with Significant Clinical Activity in Relapsed and Refractory Chronic Lymphocytic Leukemia

Dinaciclib (SCH727965) is a selective CDKi chosen for clinical development based upon a favorable therapeutic index in cancer xenograft models. We performed a phase I dose escalation study of dinaciclib in relapsed and refractory chronic lymphocytic leukemia (CLL) patients with intact organ function and WBC<200 × 109 /l. Five separate dose levels (5 mg/m2, 7 mg/m2, 10 mg/m2, 14 mg/m2 and 17 mg/m2) were explored dosing on a weekly schedule × 3 with 1 week off (4-week cycles) using a standard 3+3 design with expansion cohorts to optimize safety. Fifty-two patients were enrolled with relapsed and refractory CLL. Escalation through cohorts occurred with two dose-limiting toxicity (DLTs) at the 17 mg/m2 dose (tumor lysis syndrome (TLS) and pneumonia). The phase II expansion occurred at 14 mg/m2 with 16 patients receiving this dose with one DLT (TLS). Additional stepped up dosing to the maximum tolerated dose was examined in 19 patients at this dose. Adverse events included cytopenias, transient laboratory abnormalities and TLS. Responses occurred in 28 (54%) of patients independent of del(17)(p13.1) with a median progression-free survival of 481 days. Dinaciclib is clinically active in relapsed CLL including those patients with high risk del(17)(p13.1) disease and warrants future study.

Randomized phase 2 study of the cyclin-dependent kinase inhibitor dinaciclib (MK-7965) versus erlotinib in patients with non-small cell lung cancer☆

OBJECTIVES Dinaciclib (MK-7965, formerly SCH 727965), a novel, small-molecule inhibitor of cyclin-dependent kinases, has been shown to induce apoptosis in preclinical studies of human tumor cell lines, including non-small cell lung cancer (NSCLC) cells. Erlotinib, an epidermal growth factor receptor inhibitor, is approved for the treatment of advanced NSCLC as second- or third-line therapy. This phase 2, randomized, multicenter, open-label study compared dinaciclib with erlotinib in patients with previously treated NSCLC. MATERIALS AND METHODS The study was comprised of 2 parts: in part 1, patients were randomized to either intravenous (IV) dinaciclib (50 mg/m2) or oral erlotinib (150 mg) using an adaptive Bayesian design that adjusted the randomization ratio in favor of the more active arm, and in part 2, patients who had progressed on erlotinib were permitted to cross over to receive dinaciclib at the same dosage as in part 1. Patients were followed until disease progression or death, initiation of nonstudy cancer treatment, discontinuation, or withdrawal of consent. The primary efficacy end point was time-to-progression (TTP) in part 1 and objective response rate (ORR) in part 2. RESULTS Based on Kaplan-Meier estimates, the median TTP was 1.49 months (95% confidence interval [CI]: 1.31, 2.63) following initial treatment with dinaciclib, compared with 1.58 months (95% CI: 1.38, 2.83) with erlotinib. No objective responses were observed following initial treatment with dinaciclib. Common severe (grade 3 or 4) drug-related adverse effects included neutropenia, leukopenia, vomiting, and diarrhea. CONCLUSIONS Dinaciclib, administered IV, was well tolerated at the 50 mg/m2 dose, but does not have activity as monotherapy in previously treated NSCLC. Evaluation of dinaciclib in combination with other agents for other indications including breast cancer and multiple myeloma is in progress.

Efficacy and safety of dinaciclib versus ofatumumab in patients with relapsed/refractory chronic lymphocytic leukemia

To the editor: Novel approaches targeting molecules involved in intracellular pathways that are crucial for the survival and proliferation of the leukemic clone have been recently approved for the treatment of chronic lymphocytic leukemia (CLL) patients. Nevertheless, CLL remains incurable outside

Phase 1 safety, pharmacokinetic and pharmacodynamic study of the cyclin-dependent kinase inhibitor dinaciclib administered every three weeks in patients with advanced malignancies

Background:Dinaciclib is a potent inhibitor of cell cycle and transcriptional cyclin-dependent kinases. This Phase 1 study evaluated the safety, tolerability and pharmacokinetics of various dosing schedules of dinaciclib in advanced solid tumour patients and assessed pharmacodynamic and preliminary anti-tumour activity.Methods:In part 1, patients were enrolled in escalating cohorts of 2-h infusions administered once every 3 weeks, utilising an accelerated titration design until a recommended phase 2 dose (RP2D) was defined. In part 2, 8- and 24-h infusions were evaluated. Pharmacokinetic parameters were determined for all schedules. Pharmacodynamic effects were assessed with an ex vivo stimulated lymphocyte proliferation assay performed in whole blood.Effects of dinaciclib on retinoblastoma (Rb) phosphorylation and other CDK targets were evaluated in skin and tumour biopsies. In addition to tumour size, metabolic response was evaluated by 18F-fluorodeoxyglucose-positron emission tomography.Results:Sixty-one patients were enrolled to parts 1 and 2. The RP2Ds were 50, 7.4 and 10.4 mg m−2 as 2- 8- and 24-hour infusions, respectively. Dose-limiting toxicities included pancytopenia, neutropenic fever, elevated transaminases, hyperuricemia and hypotension. Pharmacokinetics demonstrated rapid distribution and a short plasma half-life. Dinaciclib suppressed proliferation of stimulated lymphocytes. In skin and tumour biopsies, dinaciclib reduced Rb phosphorylation at CDK2 phospho-sites and modulated expression of cyclin D1 and p53, suggestive of CDK9 inhibition. Although there were no RECIST responses, eight patients had prolonged stable disease and received between 6 and 30 cycles. Early metabolic responses occurred.Conclusions:Dinaciclib is tolerable at doses demonstrating target engagement in surrogate and tumour tissue.