Janna Christy‐Bittel

BACKGROUND: V600E mutation have a poor prognosis, with a median overall survival of 4 to 6 months after failure of initial therapy. Inhibition of BRAF alone has limited activity because of pathway reactivation through epidermal growth factor receptor signaling. METHODS: V600E-mutated metastatic colorectal cancer who had had disease progression after one or two previous regimens. Patients were randomly assigned in a 1:1:1 ratio to receive encorafenib, binimetinib, and cetuximab (triplet-therapy group); encorafenib and cetuximab (doublet-therapy group); or the investigators' choice of either cetuximab and irinotecan or cetuximab and FOLFIRI (folinic acid, fluorouracil, and irinotecan) (control group). The primary end points were overall survival and objective response rate in the triplet-therapy group as compared with the control group. A secondary end point was overall survival in the doublet-therapy group as compared with the control group. We report here the results of a prespecified interim analysis. RESULTS: The median overall survival was 9.0 months in the triplet-therapy group and 5.4 months in the control group (hazard ratio for death, 0.52; 95% confidence interval [CI], 0.39 to 0.70; P<0.001). The confirmed response rate was 26% (95% CI, 18 to 35) in the triplet-therapy group and 2% (95% CI, 0 to 7) in the control group (P<0.001). The median overall survival in the doublet-therapy group was 8.4 months (hazard ratio for death vs. control, 0.60; 95% CI, 0.45 to 0.79; P<0.001). Adverse events of grade 3 or higher occurred in 58% of patients in the triplet-therapy group, in 50% in the doublet-therapy group, and in 61% in the control group. CONCLUSIONS: V600E mutation. (Funded by Array BioPharma and others; BEACON CRC ClinicalTrials.gov number, NCT02928224; EudraCT number, 2015-005805-35.).

PURPOSE BEACON CRC evaluated encorafenib plus cetuximab with or without binimetinib versus investigators' choice of irinotecan or FOLFIRI plus cetuximab in patients with BRAFV600E–mutant metastatic colorectal cancer (mCRC), after progression on 1-2 prior regimens. In the previously reported primary analysis, encorafenib, binimetinib plus cetuximab (ENCO/BINI/CETUX; triplet) and encorafenib plus cetuximab (ENCO/CETUX; doublet) regimens improved overall survival (OS) and objective response rate (ORR; by blinded central review) versus standard of care. The purpose of this analysis was to report updated efficacy and safety data. METHODS In this open-label, phase III trial, 665 patients with BRAF V600E–mutant mCRC were randomly assigned 1:1:1 to receive triplet, doublet, or control. Primary end points were OS and independently reviewed ORR comparing triplet to control. OS for doublet versus control was a key secondary end point. Updated analyses include 6 months of additional follow-up and ORR for all randomized patients. RESULTS Patients received triplet (n = 224), doublet (n = 220), or control (n = 221). Median OS was 9.3 months (95% CI, 8.2 to 10.8) for triplet and 5.9 months (95% CI, 5.1 to 7.1) for control (hazard ratio [HR], 0.60 [95% CI, 0.47 to 0.75]). Median OS for doublet was 9.3 months (95% CI, 8.0 to 11.3) (HR v control, 0.61 [95% CI, 0.48 to 0.77]). Confirmed ORR was 26.8% (95% CI, 21.1% to 33.1%) for triplet, 19.5% (95% CI, 14.5% to 25.4%) for doublet, and 1.8% (95% CI, 0.5% to 4.6%) for control. Adverse events were consistent with the prior primary analysis, with grade ≥ 3 adverse events in 65.8%, 57.4%, and 64.2% for triplet, doublet, and control, respectively. CONCLUSION In the BEACON CRC study, encorafenib plus cetuximab improved OS, ORR, and progression-free survival in previously treated patients in the metastatic setting compared with standard chemotherapy. Based on the primary and updated analyses, encorafenib plus cetuximab is a new standard care regimen for previously treated patients with BRAF V600E mCRC.

PURPOSE To determine the safety and preliminary efficacy of selective combination targeted therapy for BRAF V600E–mutant metastatic colorectal cancer (mCRC) in the safety lead-in phase of the open-label, randomized, three-arm, phase III BEACON Colorectal Cancer trial ( ClinicalTrials.gov identifier: NCT02928224; European Union Clinical Trials Register identifier: EudraCT2015-005805-35). PATIENTS AND METHODS Before initiation of the randomized portion of the BEACON Colorectal Cancer trial, 30 patients with BRAF V600E–mutant mCRC who had experienced treatment failure with one or two prior regimens were to be recruited to a safety lead-in of encorafenib 300 mg daily, binimetinib 45 mg twice daily, plus standard weekly cetuximab. The primary end point was safety, including the incidence of dose-limiting toxicities. Efficacy end points included overall response rate, progression-free survival, and overall survival. RESULTS Among the 30 treated patients, dose-limiting toxicities occurred in five patients and included serous retinopathy (n = 2), reversible decreased left ventricular ejection fraction (n = 1), and cetuximab-related infusion reactions (n = 2). The most common grade 3 or 4 adverse events were fatigue (13%), anemia (10%), increased creatine phosphokinase (10%), increased AST (10%), and urinary tract infections (10%). In 29 patients with BRAF V600E–mutant tumors (one patient had a non– BRAF V600E–mutant tumor and was not included in the efficacy analysis), the confirmed overall response rate was 48% (95% CI, 29.4% to 67.5%), median progression-free survival was 8.0 months (95% CI, 5.6 to 9.3 months), and median overall survival was 15.3 months (95% CI, 9.6 months to not reached), with median duration of follow-up of 18.2 months (range, 16.6 to 19.8 months). CONCLUSION In the safety lead-in, the safety and tolerability of the encorafenib, binimetinib, and cetuximab regimen is manageable and acceptable for initiation of the randomized portion of the study. The observed efficacy is promising compared with available therapies and, if confirmed in the randomized portion of the trial, could establish this regimen as a new standard of care for previously treated BRAF V600E–mutant mCRC.

PURPOSE Low-grade serous ovarian carcinomas (LGSOCs) have historically low chemotherapy responses. Alterations affecting the MAPK pathway, most commonly KRAS/BRAF, are present in 30%-60% of LGSOCs. The purpose of this study was to evaluate binimetinib, a potent MEK1/2 inhibitor with demonstrated activity across multiple cancers, in LGSOC. METHODS This was a 2:1 randomized study of binimetinib (45 mg twice daily) versus physician’s choice chemotherapy (PCC). Eligible patients had recurrent measurable LGSOC after ≥ 1 prior platinum-based chemotherapy but ≤ 3 prior chemotherapy lines. The primary end point was progression-free survival (PFS) by blinded independent central review (BICR); additional assessments included overall survival (OS), overall response rate (ORR), duration of response (DOR), clinical-benefit rate, biomarkers, and safety. RESULTS A total of 303 patients were randomly assigned to an arm of the study at the time of interim analysis (January 20, 2016). Median PFS by BICR was 9.1 months (95% CI, 7.3 to 11.3) for binimetinib and 10.6 months (95% CI, 9.2 to 14.5) for PCC (hazard ratio,1.21; 95%CI, 0.79 to 1.86), resulting in early study closure according to a prespecified futility boundary after 341 patients had enrolled. Secondary efficacy end points were similar in the two groups: ORR 16% (complete response [CR]/partial responses[PRs], 32) versus 13% (CR/PRs, 13); median DOR, 8.1 months (range, 0.03 to ≥ 12.0 months) versus 6.7 months (0.03 to ≥ 9.7 months); and median OS, 25.3 versus 20.8 months for binimetinib and PCC, respectively. Safety results were consistent with the known safety profile of binimetinib; the most common grade ≥ 3 event was increased blood creatine kinase level (26%). Post hoc analysis suggests a possible association between KRAS mutation and response to binimetinib. Results from an updated analysis (n = 341; January 2019) were consistent. CONCLUSION Although the MEK Inhibitor in Low-Grade Serous Ovarian Cancer Study did not meet its primary end point, binimetinib showed activity in LGSOC across the efficacy end points evaluated. A higher response to chemotherapy than expected was observed and KRAS mutation might predict response to binimetinib.

BACKGROUND: Binimetinib (MEK162; ARRY-438162) is a potent and selective oral MEK 1/2 inhibitor. This phase 1 study determined the maximum tolerated dose (MTD), safety, pharmacokinetic and pharmacodynamic profiles, and preliminary anti-tumour activity of binimetinib in patients with advanced solid tumours, with expansion cohorts of patients with biliary cancer or KRAS- or BRAF-mutant colorectal cancer. METHODS: Binimetinib was administered twice daily. Expansion cohorts were enroled after MTD determination following a 3+3 dose-escalation design. Pharmacokinetic properties were determined from plasma samples. Tumour samples were assessed for mutations in RAS, RAF, and other relevant genes. Pharmacodynamic properties were evaluated in serum and skin punch biopsy samples. RESULTS: Ninety-three patients received binimetinib (dose-escalation phase, 19; expansion, 74). The MTD was 60 mg twice daily, with dose-limiting adverse events (AEs) of dermatitis acneiform and chorioretinopathy. The dose for expansion patients was subsequently decreased to 45 mg twice daily because of the frequency of treatment-related ocular toxicity at the MTD. Common AEs across all dose levels included rash (81%), nausea (56%), vomiting (52%), diarrhoea (51%), peripheral oedema (46%), and fatigue (43%); most were grade 1/2. Dose-proportional increases in binimetinib exposure were observed and target inhibition was demonstrated in serum and skin punch biopsy samples. Three patients with biliary cancer had objective responses (one complete and two partial). CONCLUSIONS: Binimetinib demonstrated a manageable safety profile, target inhibition, and dose-proportional exposure. The 45 mg twice daily dose was identified as the recommended phase 2 dose. The three objective responses in biliary cancer patients are encouraging and support further evaluation in this population.