The effect of food on the pharmacokinetics of oral ibrutinib in healthy participants and patients with chronic lymphocytic leukemia.

PURPOSE: To assess ibrutinib pharmacokinetics under fasted and fed conditions, impact of food-intake timing, and the safety and tolerability. METHODS: Three studies were analyzed. Study 1 was a randomized, open-label, single-dose, four-way crossover study in 44 healthy participants. Study 2 was a randomized, repeat-dose crossover study in 16 patients with previously treated chronic lymphocytic leukemia (CLL). Ibrutinib dose was 420 mg in both studies. Study 3 was an open-label, sequential study to assess the effect of a standard breakfast on ibrutinib 560 mg in eight healthy participants. RESULTS: Administration of single-dose ibrutinib under fasting conditions (study 1) resulted in approximately 60 % of exposure compared with drug intake either 30 min before, 30 min after (fed), or 2 h after a high-fat meal. Similar food effect was observed (study 3) when ibrutinib was given 30 min before meal. In CLL patients (study 2), the C max and AUC under fasting conditions were 43 and 61 %, respectively, relative to fed conditions. When administered once-daily in uncontrolled food-intake conditions (≥30 min before or 2 h after), exposures were slightly (≈30 %) lower than in fed condition. When corrected for repeated dosing, pharmacokinetic parameters in healthy participants and patients were comparable. Ibrutinib was generally well tolerated in all settings studied. CONCLUSIONS: Ibrutinib administered in fasted condition reduces exposure to approximately 60 % as compared with dosing in proximity to food-intake, regardless of timing/type of meal. Because repeated drug intake in fasted condition is unlikely, no food restrictions may be needed to administer ibrutinib.

Population pharmacokinetic model of ibrutinib, a Bruton tyrosine kinase inhibitor, in patients with B cell malignancies.

PURPOSE: Ibrutinib is an oral Bruton's tyrosine kinase inhibitor, recently approved for the treatment of mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) patients with at least one prior therapy. We developed a population pharmacokinetic (PK) model for ibrutinib in patients. METHODS: Ibrutinib PK data (3,477 observations/245 patients) were available from the following clinical studies: (1) A phase I dose-escalation study in recurrent B cell malignancies (dose levels of 1.25-12.5 mg/kg/day and fixed dose of 560 mg/day); (2) a phase II study in MCL (fixed dose level of 560 mg/day); (3) a phase Ib/II dose-finding study in CLL (fixed dose levels of 420 and 840 mg/day). Different compartmental PK models were explored using nonlinear mixed effects modeling. RESULTS: A two-compartment PK model with sequential zero-first-order absorption and first-order elimination was able to characterize the PK of ibrutinib. The compound was rapidly absorbed, had a high oral plasma clearance (approximately 1,000 L/h) and a high apparent volume of distribution at steady state (approximately 10,000 L). PK parameters were not dependent on dose, study, or clinical indication. The fasting state was characterized by a 67 % relative bioavailability compared with the meal conditions used in the trials and administration after a high-fat meal. Body weight and coadministration of antacids marginally increased volume of distribution and duration of absorption, respectively. CONCLUSIONS: The proposed population PK model was able to describe the plasma concentration-time profiles of ibrutinib across various trials. The linear model indicated that the compound's PK was dose independent and time independent.

Pharmacokinetic/pharmacodynamic modelling-based optimisation of administration schedule for the histone deacetylase inhibitor abexinostat (S78454/PCI-24781) in phase I.

Abexinostat, an oral pan-histone deacetylase inhibitor (HDACi), was evaluated in patients with advanced solid tumours in two single agent phase I studies (PCYC-402 and CL1-78454-002). In PCYC-402 study testing four different administration schedules, the maximum tolerated dose (MTD) was established at 75 mg/m(2) BID (twice daily) and the recommended dose at 60 mg/m(2) BID regardless of the schedule tested. The dose limiting toxicity (DLT), consistently observed across all these schedules, was reversible thrombocytopenia. The CL1-78454-002 study was initially investigating an additional schedule of 14 days on/7 days off. While testing two first cohorts, thrombocytopenia was observed without reaching DLT. To address this issue, a pharmacokinetic/pharmacodynamic (PK/PD) model was used to predict the optimal schedule allowing higher doses with minimal thrombocytopenia. Several administration schedules were simulated using this model. A 4 days on/3 days off schedule was associated with the smallest platelet decrease. Accordingly, the CL1-78454-002 study was amended. After reaching MTD1 (75 mg/m(2) BID) with the initial schedule, subsequent cohorts received abexinostat on a revised schedule of 4 days on/3 days off, starting at one dose level below MTD1 (60 mg/m(2) BID). As expected, the dose-escalation continued for two more dose levels beyond MTD1. The MTD2 reached for this optimised schedule was 105 mg/m(2) BID and the recommended dose 90 mg/m(2) BID. In conclusion, early understanding of toxicities and PK determination allowed us to build a PK/PD model of thrombocytopenia, which predicted the optimal administration schedule. This optimised schedule is currently used in the trials in solid tumours with abexinostat.

The Bruton tyrosine kinase inhibitor PCI-32765 blocks B-cell activation and is efficacious in models of autoimmune disease and B-cell malignancy.

Activation of the B-cell antigen receptor (BCR) signaling pathway contributes to the initiation and maintenance of B-cell malignancies and autoimmune diseases. The Bruton tyrosine kinase (Btk) is specifically required for BCR signaling as demonstrated by human and mouse mutations that disrupt Btk function and prevent B-cell maturation at steps that require a functional BCR pathway. Herein we describe a selective and irreversible Btk inhibitor, PCI-32765, that is currently under clinical development in patients with B-cell non-Hodgkin lymphoma. We have used this inhibitor to investigate the biologic effects of Btk inhibition on mature B-cell function and the progression of B cell-associated diseases in vivo. PCI-32765 blocked BCR signaling in human peripheral B cells at concentrations that did not affect T cell receptor signaling. In mice with collagen-induced arthritis, orally administered PCI-32765 reduced the level of circulating autoantibodies and completely suppressed disease. PCI-32765 also inhibited autoantibody production and the development of kidney disease in the MRL-Fas(lpr) lupus model. Occupancy of the Btk active site by PCI-32765 was monitored in vitro and in vivo using a fluorescent affinity probe for Btk. Active site occupancy of Btk was tightly correlated with the blockade of BCR signaling and in vivo efficacy. Finally, PCI-32765 induced objective clinical responses in dogs with spontaneous B-cell non-Hodgkin lymphoma. These findings support Btk inhibition as a therapeutic approach for the treatment of human diseases associated with activation of the BCR pathway.

Quinazolinone fungal efflux pump inhibitors. Part 3: (N-methyl)piperazine variants and pharmacokinetic optimization.

Further structure-activity relationships of a novel series of fungal efflux pump inhibitors with respect to potentiation of the activity of fluconazole against strains of C. albicans and C. glabrata over-expressing ABC-type efflux pumps are systematically explored. Rat protein binding and pharmacokinetics of selected analogues are reported.