The clinical practice guidelines for the treatment of patients with colorectal cancer have been updated by NCCN to include the combination of encorafenib plus binimetinib in addition to EGFR inhibition with either cetuximab or panitumumab as a Category 2a treatment recommendation for patients with <em>BRAF</em> V600E–mutant metastatic CRC, after 1 or 2 prior therapies for metastatic disease.
Scott Kopetz, MD, PhD, FACP
The clinical practice guidelines for the treatment of patients with colorectal cancer (CRC) have been updated by the NCCN to include the combination of encorafenib (Braftovi) plus binimetinib (Mektovi) in addition to EGFR inhibition with either cetuximab (Erbitux) or panitumumab (Vectibix) as a Category 2a treatment recommendation for patients withBRAFV600Emutant metastatic CRC (mCRC), after 1 or 2 prior therapies for metastatic disease.
NCCN based this recommendation on results from the BEACON CRC trial, according to a press release from Array BioPharma Inc, the manufacturer of encorafenib and binimetinib. The safety lead-in (SLI) phase of this trial demonstrated that clinical outcomes with the combination of the BRAF inhibitor encorafenib, the MEK inhibitor binimetinib, and cetuximab exceeded historic data in patients withBRAFV600E-mutant metastatic CRC, according to data reported at the 2019 Gastrointestinal Cancers Symposium.
Results from 30 patients showed an estimated median progression-free survival (PFS) of 8.0 months and an estimated median overall survival (OS) of 15.3 months with a median duration of follow-up of 18.2 months. The overall response rate (ORR) was 48% by local assessment, with 3 patients achieving a complete response (CR).
"With no current FDA-approved therapies forBRAFCRC, this combination represents an important treatment option for this patient population," BEACON trial lead author Scott Kopetz, MD, PhD., FACP, Associate Professor, Department of Gastrointestinal Medical Oncology, Division of Cancer Medicine at The University of Texas MD Anderson Cancer Center, said in a statement.
"Historical published benchmarks inBRAFV600Emutant mCRC patients, whose disease has progressed after one or two prior lines of therapy, are an overall response generally between 4% to 8%, a median progression-free survival of 2 to 3 months, and median overall survival of 4 to 6 months. The NCCN recommendation underscores the potential for this triplet combination to benefit these patients in critical need."
BEACON CRC is a randomized open-label 3-arm phase III study evaluating the triplet compared with irinotecan-based chemotherapy plus cetuximab and encorafenib plus cetuximab in patients withBRAFV600E-mutant metastatic colorectal cancer after 1 or 2 prior lines of treatment in the metastatic setting. Enrollment was completed in 2018. BEACON SLI was conducted to evaluate safety and efficacy of the triplet prior to randomizing patients to the phase III portion.
The primary endpoint of BEACON CRC is OS associated with the triplet combination compared with the control arm.
Previously, as reported at the 2018 Gastrointestinal Cancers Symposium, the triplet combination was generally well-tolerated in the SLI. Of the 2 patients who discontinued treatment due to adverse events, 1 was considered related to treatment. The most common grade ≥3 adverse events were fatigue (n = 4), urinary tract infection (n = 3), an increase in the level of aspartate aminotransferase (n = 3), and an increase in the level of blood creatine kinase (n = 3). At that report, in the 29 patients with aBRAFV600E mutation, the estimated median PFS was 8 months and the confirmed ORR was 48%, with 3 patients achieving complete responses.2
The 30 patients treated in the SLI portion of the study received encorafenib at 300 mg daily, binimetinib at 45 mg twice daily, and cetuximab at the standard weekly dose of 400 mg/m2, then 250 mg/m2once weekly. Of the 30 patients, 29 had aBRAFV600E mutation. Median patient age was 59 years. Sixty percent had received 1 prior line of therapy and 40% received 2 prior lines. Forty-three percent received prior irinotecan. At the data cutoff of September 2, 2018, 6 patients remained on treatment.
Efficacy was evaluated in the 29 patients withBRAFV600E mutations, who were on study treatment for a median of 7.9 months. The confirmed 48% ORR by local assessment consisted of 3 CRs, 11 (38%) partial responses (PRs), and 13 (45%) with stable disease (SD). The 41% ORR by central assessment included 2 CRs, 10 (34%) PRs, and 13 (45%) with SD. The median duration of response was 5.5 months by local assessment and 8.2 months by central assessment. The duration of response estimate was ≥6 months in 43% of the responders by local assessment and 73% by central assessment.
When response was stratified by number of previous lines of therapy, the ORR by local assessment was 59% with 1 previous line (8 PRs and 2 CRs) and 33% (3 PRs and 1 CR) with 2 previous lines, and by central assessment, the ORR was 53% (8 PRs and 1 CR) with 1 previous line of therapy and 25% (2 PRs and 1 CR) with 2 previous lines.
The 6-month OS was 86.2% and the 12-month OS was 62.1%. Adverse events (AEs) were similar to those previously reported with BRAF, MEK, and EGFR inhibitors. The most common grade 3/4 AEs were fatigue (n = 4), anemia, increased level of creatine kinase, asthenia, and urinary tract infection (n = 3 for each AE); dyspnea (n = 2); and gastrointestinal toxicities such as nausea, vomiting, decreased appetite (n = 2 for each). Six patients (20%) had at least 1 drug discontinued due to AEs, 1 of whom discontinued all 3 drugs due to grade-2 fatigue.