Phase Ib Study of Combination Therapy with MEK Inhibitor Binimetinib and Phosphatidylinositol 3-Kinase Inhibitor Buparlisib in Patients with Advanced Solid Tumors with RAS/RAF Alterations.

BACKGROUND: This multicenter, open-label, phase Ib study investigated the safety and efficacy of binimetinib (MEK inhibitor) in combination with buparlisib (phosphatidylinositol 3-kinase [PI3K] inhibitor) in patients with advanced solid tumors with RAS/RAF alterations. MATERIALS AND METHODS: Eighty-nine patients were enrolled in the study. Eligible patients had advanced solid tumors with disease progression after standard therapy and/or for which no standard therapy existed. Evaluable disease was mandatory, per RECIST version 1.1 and Eastern Cooperative Oncology Group performance status 0-2. Binimetinib and buparlisib combinations were explored in patients with KRAS-, NRAS-, or BRAF-mutant advanced solid tumors until the maximum tolerated dose and recommended phase II dose (RP2D) were defined. The expansion phase comprised patients with epidermal growth factor receptor (EGFR)-mutant, advanced non-small cell lung cancer, after progression on an EGFR inhibitor; advanced RAS- or BRAF-mutant ovarian cancer; or advanced non-small cell lung cancer with KRAS mutation. RESULTS: At data cutoff, 32/89 patients discontinued treatment because of adverse events. RP2D for continuous dosing was buparlisib 80 mg once daily/binimetinib 45 mg twice daily. The toxicity profile of the combination resulted in a lower dose intensity than anticipated. Six (12.0%) patients with RAS/BRAF-mutant ovarian cancer achieved a partial response. Pharmacokinetics of binimetinib were not altered by buparlisib. Pharmacodynamic analyses revealed downregulation of pERK and pS6 in tumor biopsies. CONCLUSION: Although dual inhibition of MEK and the PI3K pathways showed promising activity in RAS/BRAF ovarian cancer, continuous dosing resulted in intolerable toxicities beyond the dose-limiting toxicity monitoring period. Alternative schedules such as pulsatile dosing may be advantageous when combining therapies. IMPLICATIONS FOR PRACTICE: Because dysregulation of the mitogen-activated protein kinase (MAPK) and the phosphatidylinositol 3-kinase (PI3K) pathways are both frequently involved in resistance to current targeted therapies, dual inhibition of both pathways may be required to overcome resistance mechanisms to single-agent tyrosine kinase inhibitors or to treat cancers with driver mutations that cannot be directly targeted. A study investigating the safety and efficacy of combination binimetinib (MEK inhibitor) and buparlisib (PI3K inhibitor) in patients harboring alterations in the RAS/RAF pathway was conducted. The results may inform the design of future combination therapy trials in patients with tumors harboring mutations in the PI3K and MAPK pathways.

A phase II pharmacodynamic study of erlotinib in patients with advanced non-small cell lung cancer previously treated with platinum-based chemotherapy.

PURPOSE: To examine potential markers of clinical benefit and the effects of erlotinib on the epidermal growth factor receptor (EGFR) signaling pathway in advanced non-small cell lung cancer patients refractory to platinum-based chemotherapy. EXPERIMENTAL DESIGN: Patients were given erlotinib (150 mg/d). Tumor biopsies were done immediately before treatment and in a subgroup of patients after 6 weeks' treatment. RESULTS: Of 73 evaluable patients, 7 (10%) had partial response and 28 (38%) had stable disease. In 53 patients with baseline tumor samples, no relationship was observed between pretreatment levels of EGFR, phosphorylated (p)-EGFR, p-AKT, p-mitogen-activated protein kinase (MAPK), or p27 and clinical benefit (i.e., response, or stable disease >/=12 weeks). Tumors from 15 of 57 patients had high EGFR gene copy number, assessed using fluorescence in situ hybridization (FISH positive), 10 of whom had clinical benefit, compared with 5 of 42 FISH-negative patients. FISH-positive patients had longer median progression-free [137 versus 43 days, P = 0.002; hazard ratio (HR), 0.37] and overall (226 versus 106 days, P = 0.267; HR, 0.70) survival than FISH-negative patients. In paired biopsy samples from 14 patients, p-EGFR (P = 0.002), p-MAPK (P = 0.001), and Ki-67 (P = 0.025) levels were significantly reduced after 6 weeks' treatment. Apoptosis was significantly increased in patients with clinical benefit (P = 0.029), and may be a marker of clinical benefit. CONCLUSION: In this study, EGFR FISH-positive status was associated with improved outcome after erlotinib therapy. Erlotinib led to reduced levels of p-EGFR, p-MAPK, and Ki-67, and stimulated apoptosis in tumor samples from patients with clinical benefit.

Mechanistic Insights of an Immunological Adverse Event Induced by an Anti-KIT Antibody Drug Conjugate and Mitigation Strategies.

Purpose: Hypersensitivity reactions (HSRs) were observed in three patients dosed in a phase I clinical trial treated with LOP628, a KIT targeted antibody drug conjugate. Mast cell degranulation was implicated as the root cause for the HSR. Underlying mechanism of this reported HSR was investigated with an aim to identifying potential mitigation strategies.Experimental Design: Biomarkers for mast cell degranulation were evaluated in patient samples and in human peripheral blood cell-derived mast cell (PBC-MC) cultures treated with LOP628. Mitigation strategies interrogated include pretreatment of mast cells with small molecule inhibitors that target KIT or signaling pathways downstream of FcεR1, FcγR, and treatment with Fc silencing antibody formats.Results: Transient elevation of serum tryptase was observed in patients 1-hour posttreatment of LOP628. In agreement with the clinical observation, LOP628 and its parental antibody LMJ729 induced degranulation of human PBC-MCs. Unexpectedly, KIT small molecule inhibitors did not abrogate mast cell degranulation. By contrast, small molecule inhibitors that targeted pathways downstream of Fc receptors blunted degranulation. Furthermore, interference of the KIT antibody to engage Fc receptors by pre-incubation with IgG or using engineered Fc silencing mutations reduced or prevented degranulation. Characterization of Fcγ receptors revealed human PBC-MCs expressed both FcγRII and low levels of FcγRI. Interestingly, increasing the level of FcγRI upon addition of IFNγ, significantly enhanced LOP628-mediated mast cell degranulation.Conclusions: Our data suggest LOP628-mediated mast cell degranulation is the likely cause of HSR observed in the clinic due to co-engagement of the FcγR and KIT, resulting in mast cell activation. Clin Cancer Res; 24(14); 3465-74. ©2018 AACR.

LJM716 in Japanese patients with head and neck squamous cell carcinoma or HER2-overexpressing breast or gastric cancer.

PURPOSE: Human epidermal growth factor receptor 3 (HER3) has been identified as an important component of many receptor tyrosine kinase-driven cancers. LJM716 is a human IgG monoclonal antibody that binds HER3, trapping it in an inactive conformation. In this study, a phase I dose escalation was performed with a primary objective to establish the maximum tolerated dose and/or the recommended dose of LJM716 in Japanese patients with selected advanced solid tumors. Secondary objectives included the evaluation of the safety and tolerability, preliminary antitumor activity, and pharmacokinetics of LJM716 in Japanese patients. METHODS: LJM716 was administered intravenously at doses of 10, 20, or 40 mg/kg once weekly, in 28-day cycles, to 12 patients with HER2-amplified breast cancer or gastric cancer, or with esophageal squamous cell carcinoma or squamous cell carcinoma of the head and neck, regardless of HER2 status. RESULTS: The maximum tolerated dose was not reached, and the recommended dose was established at 40 mg/kg. No dose-limiting toxicities were observed in the first cycle. The most frequently reported adverse events were diarrhea, fatigue, stomatitis, pyrexia, and paronychia. One unconfirmed partial response was observed in a patient with breast cancer, and 50% of the patients achieved stable disease as the best overall response. Exposure increased with ascending dose, and half-life was estimated to be 11-14 days. No anti-LJM716 antibodies were detected. CONCLUSIONS: LJM716 was well tolerated in Japanese patients, and a degree of tumor shrinkage was observed. CLINICAL TRIAL INFORMATION: ClinicalTrials.gov NCT01911936.