The effect of ketoconazole on the pharmacokinetics and pharmacodynamics of ixabepilone: a first in class epothilone B analogue in late-phase clinical development.

PURPOSE: To determine if ixabepilone is a substrate for cytochrome P450 3A4 (CYP3A4) and if its metabolism by this cytochrome is clinically important, we did a clinical drug interaction study in humans using ketoconazole as an inhibitor of CYP3A4. EXPERIMENTAL DESIGN: Human microsomes were used to determine the cytochrome P450 enzyme(s) involved in the metabolism of ixabepilone. Computational docking (CYP3A4) studies were done for epothilone B and ixabepilone. A follow-up clinical study was done in patients with cancer to determine if 400 mg/d ketoconazole (inhibitor of CYP3A4) altered the pharmacokinetics, drug-target interactions, and pharmacodynamics of ixabepilone. RESULTS: Molecular modeling and human microsomal studies predicted ixabepilone to be a good substrate for CYP3A4. In patients, ketoconazole coadministration resulted in a maximum ixabepilone dose administration to 25 mg/m(2) when compared with single-agent therapy of 40 mg/m(2). Coadministration of ketoconazole with ixabepilone resulted in a 79% increase in AUC(0-infinity). The relationship of microtubule bundle formation in peripheral blood mononuclear cells to plasma ixabepilone concentration was well described by the Hill equation. Microtubule bundle formation in peripheral blood mononuclear cells correlated with neutropenia. CONCLUSIONS: Ixabepilone is a good CYP3A4 substrate in vitro; however, in humans, it is likely to be cleared by multiple mechanisms. Furthermore, our results provide evidence that there is a direct relationship between ixabepilone pharmacokinetics, neutrophil counts, and microtubule bundle formation in PBMCs. Strong inhibitors of CYP3A4 should be used cautiously in the context of ixabepilone dosing.

The Fast Real-time Assessment of Combination Therapies in Immuno-ONcology (FRACTION) program: innovative, high-throughput clinical screening of immunotherapies.

BACKGROUND: The unprecedented success of immuno-oncology (I-O) agents targeting the cytotoxic T lymphocyte-associated antigen 4 and programmed death-1/programmed death-ligand 1 pathways has stimulated the rapid development of other I-O agents against novel immune targets. Bristol-Myers Squibb has designed a novel phase II platform trial, the Fast Real-time Assessment of Combination Therapies in Immuno-ONcology (FRACTION) Program, to efficiently identify promising combinations for patients with specific malignancies. The concept and study design of the FRACTION Program-currently ongoing in patients with advanced non-small-cell lung cancer (FRACTION-Lung), gastric cancer (FRACTION-Gastric Cancer) and renal cell carcinoma (FRACTION-RCC)-are described. METHODS: The FRACTION Program comprises open-label, phase II studies that use adaptive randomisation designs with rolling combination regimens. Master Protocols provide the overall study design framework, whereas Sub-Protocols introduced over time provide details on specific I-O combination therapies to which patients may be randomised. In a Master Protocol, patients are enrolled into different Study Tracks based on characteristics such as prior I-O therapy experience. Patients who progress may be rerandomised to other combination regimens from any ongoing Sub-Protocol. Primary objectives are to assess objective response rate, median duration of response and progression-free survival rate at 24 weeks; the secondary objective is to investigate safety and tolerability. Biomarker collection before and on treatment will facilitate identification of patient subsets who benefit most from each therapy. CONCLUSIONS: The FRACTION Program allows for the evaluation of multiple I-O combinations through individual studies for specific tumours using an adaptive trial design and continuous enrolment.