An Adaptive Physiologically Based Pharmacokinetic-Driven Design to Investigate the Effect of Itraconazole and Rifampicin on the Pharmacokinetics of Molibresib (GSK525762) in Healthy Female Volunteers.

Molibresib (GSK525762), an orally bioavailable small molecule with 2 major equipotent active metabolites, is being developed for the treatment of cancers. Molibresib is a substrate of cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp). To enable administering safe doses of molibresib to healthy volunteers, this 2-part randomized, open-label, crossover drug-drug interaction trial was conducted as an adaptive design study using physiologically based pharmacokinetic (PBPK) modeling and simulation to predict the lowest doses of molibresib that could be safely administered alone (10 mg) or with itraconazole and rifampicin (strong inhibitors and inducers of CYP3A and P-gp, respectively). PBPK simulation guided the molibresib dose (5 mg) to be administered along with itraconazole in part 1. Itraconazole increased total exposure (AUC) of molibresib by 4.15-fold with a 66% increase in Cmax , whereas the total AUC and Cmax for the 2 major active metabolites of molibresib decreased by about 70% and 87%, respectively. A second PBPK simulation was conducted with part 1 data to also include the active metabolites to update the recommendation for the molibresib dose (20 mg) with rifampicin. With rifampicin, the AUC and Cmax of molibresib decreased by approximately 91% and 80%, respectively, whereas the AUC of the 2 active metabolites decreased to a lesser extent (8%), with a 2-fold increase in Cmax . The results of this study confirmed the in vitro data that molibresib is a substrate for CYP3A4. The adaptive design, including Simcyp simulations, allowed evaluation of 2 drug interactions of an oncology drug in a single trial, thus minimizing time and exposures administered to healthy subjects.

A Phase 1/1b Study Evaluating Trametinib Plus Docetaxel or Pemetrexed in Patients With Advanced Non-Small Cell Lung Cancer.

OBJECTIVES: This two-part study evaluated trametinib, a MEK1/2 inhibitor, in combination with anticancer agents. Inhibition of MEK, a downstream effector of KRAS, demonstrated preclinical synergy with chemotherapy in KRAS-mutant NSCLC cell lines. Part 1 of this study identified recommended phase 2 doses of trametinib combinations. Part 2, reported herein, evaluated the safety, tolerability, pharmacokinetics, and efficacy of trametinib combinations in patients with NSCLC with and without KRAS mutations. METHODS: Phase 1b evaluated trametinib plus docetaxel with growth factor support (trametinib, 2.0 mg once daily, and docetaxel, 75 mg/m2 every 3 weeks) or pemetrexed (trametinib, 1.5 mg once daily, and pemetrexed, 500 mg/m2 every 3 weeks). Eligibility criteria for the expansion cohorts included metastatic NSCLC with measurable disease, known KRAS mutation status, Eastern Cooperative Oncology Group performance status of 1 or lower, and no more than two prior regimens. RESULTS: The primary end point of overall response rate (ORR) was met for both combinations. A confirmed partial response (PR) was observed in 10 of the 47 patients with NSCLC who received trametinib plus docetaxel (21%). The ORR was 18% (four PRs in 22 patients) in those with KRAS wild-type NSCLC versus 24% (six PRs in 25 patients) in those with KRAS-mutant NSCLC. Of the 42 patients with NSCLC treated with trametinib plus pemetrexed, six (14%) had a PR; the ORR was 17% (four of 23) in patients with KRAS-mutated NSCLC versus 11% (two of 19) in KRAS wild-type NSCLC. Adverse events-most commonly diarrhea, nausea, and fatigue-were manageable. CONCLUSIONS: Trametinib-plus-chemotherapy combinations were tolerable. Clinical activity exceeding the ORRs previously reported with docetaxel or pemetrexed alone in KRAS-mutated NSCLC and meeting prespecified criteria was observed.

Activity of the oral mitogen-activated protein kinase kinase inhibitor trametinib in RAS-mutant relapsed or refractory myeloid malignancies.

BACKGROUND: RAS/RAF/mitogen-activated protein kinase activation is common in myeloid malignancies. Trametinib, a mitogen-activated protein kinase kinase 1 (MEK1)/MEK2 inhibitor with activity against multiple myeloid cell lines at low nanomolar concentrations, was evaluated for safety and clinical activity in patients with relapsed/refractory leukemias. METHODS: This phase 1/2 study accrued patients with any relapsed/refractory leukemia in phase 1. In phase 2, this study accrued patients with relapsed/refractory acute myeloid leukemia (AML) or high-risk myelodysplastic syndromes (MDS) with NRAS or KRAS mutations (cohort 1); patients with AML, MDS, or chronic myelomonocytic leukemia (CMML) with a RAS wild-type mutation or an unknown mutation status (cohort 2); and patients with CMML with an NRAS or KRAS mutation (cohorts 3). RESULTS: The most commonly reported treatment-related adverse events were diarrhea, rash, nausea, and increased alanine aminotransferase levels. The phase 2 recommended dose for Trametinib was 2 mg orally daily. The overall response rates were 20%, 3%, and 27% for cohorts 1, 2, and 3, respectively, and this indicated preferential activity among RAS-mutated myeloid malignancies. Repeated cycles of trametinib were well tolerated with manageable or reversible toxicities; these results were similar to those of other trametinib studies. CONCLUSIONS: The selective, single-agent activity of trametinib against RAS-mutated myeloid malignancies validates its therapeutic potential. Combination strategies based on a better understanding of the hierarchical role of mutations and signaling in myeloid malignancies are likely to improve the response rate and duration. Cancer 2016;122:1871-9. © 2016 American Cancer Society.