On September 9, 2017 Array BioPharma (Nasdaq: ARRY) and Pierre Fabre reported results from Part 2 of the Phase 3 COLUMBUS study evaluating binimetinib, a MEK inhibitor, and encorafenib, a BRAF inhibitor, in patients with BRAF-mutant advanced, unresectable or metastatic melanoma (Press release, Array BioPharma, SEP 9, 2017, View Source [SID1234520436]). The primary analysis of Part 2 compared progression free survival (PFS) in patients treated with binimetinib 45 mg twice daily plus encorafenib 300 mg daily (COMBO300) to patients treated with encorafenib 300 mg daily as a single agent. Part 2 of the study was designed specifically to measure the contribution of binimetinib to the combination by holding the dose of encorafenib at 300 mg in both arms.

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The median PFS for patients treated with COMBO300 was 12.9 months compared to 9.2 months for patients treated with single agent encorafenib, with HR of 0.77 [95% CI 0.61-0.97, p=0.029]. As part of the trial design, the analysis was based on a Blinded Independent Central Review (BICR) of patient scans, while results by local review at the investigative site were also analyzed. COMBO300 was generally well-tolerated and reported dose intensity and adverse events were consistent with binimetinib 45 mg twice daily plus encorafenib 450 mg daily (COMBO450) results in COLUMBUS Part 1. Grade 3/4 adverse events (AEs) that occurred in 5% or more of patients receiving COMBO300 were increased gamma-glutamyltransferase (GGT) (5%), increased blood creatine phosphokinase (CK) (5%) and increased alanine aminotransferase (ALT) (5%). The incidence of selected any grade AEs of special interest, defined based on toxicities commonly associated with commercially available MEK+BRAF-inhibitor treatments for patients receiving COMBO300 included: pyrexia (17%), rash (15%), retinal pigment epithelial detachment (9%) and photosensitivity (2%). Full safety results of COLUMBUS Part 2 were presented at the 2017 ESMO (Free ESMO Whitepaper) Congress.

"The totality of the COLUMBUS results, across Part 1 and 2, including median PFS, objective response rate, dose intensity and tolerability of the combination, provide a strong and consistent theme across multiple endpoints, underscoring the promise of binimetinib plus encorafenib as an attractive treatment option for patients diagnosed with BRAF-mutant melanoma," said Keith T. Flaherty, M.D., Director of the Termeer Center for Targeted Therapy, Massachusetts General Hospital and Professor of Medicine, Harvard Medical School.

Reinhard Dummer, M.D., investigator, University Hospital Zurich, noted: "Results from COLUMBUS Part 2 clearly demonstrated the contribution of MEK to the combination and suggest that the robust activity seen with COMBO450 in COLUMBUS Part 1 may be related to the ability to increase the dose of encorafenib."

On July 5, 2017, Array announced that it submitted two NDAs to the FDA to support use of the combination of binimetinib 45 mg twice daily and encorafenib 450 mg once daily (COMBO450) for the treatment of patients with BRAF-mutant advanced, unresectable or metastatic melanoma. Array completed its NDA submissions based on findings from the pivotal Phase 3 COLUMBUS trial. In addition, Array’s European partner, Pierre Fabre, announced on August 28, 2017, that the European Medicines Agency has validated the review of the MAAs for binimetinib and encorafenib.

COLUMBUS Results
As presented at the 2016 Society for Melanoma Research Annual Congress, results from Part 1 of the COLUMBUS study showed that COMBO450 significantly extended PFS in patients with advanced BRAF-mutant melanoma, with a PFS of 14.9 months compared with 7.3 months observed with vemurafenib [hazard ratio (HR) 0.54, (95% CI 0.41-0.71, P<0.001)]. As part of the trial design, the primary analysis was based on a BICR of patient scans, while results by local review at the investigative site were also analyzed. The table below outlines the median PFS (mPFS) results, as determined by both assessments, for COMBO450 versus vemurafenib, COMBO450 versus encorafenib, and encorafenib versus vemurafenib:

mPFS BICR

mPFS Local Review
COMBO450
vs.
Vemurafenib

COMBO450
Vemurafenib

COMBO450
Vemurafenib

14.9 months
7.3 months

14.8 months
7.3 months

HR (95% CI): 0.54 (0.41-0.71); P<0.001

HR (95% CI): 0.49 (0.37-0.64); P<0.001

COMBO450
vs.
Encorafenib

COMBO450
Encorafenib

COMBO450
Encorafenib

14.9 months
9.6 months

14.8 months
9.2 months

HR (95% CI): 0.75 (0.56-1.00); P=0.051

HR (95% CI): 0.68 (0.52-0.90); P=0.006

Encorafenib
vs.
Vemurafenib

Encorafenib
Vemurafenib

Encorafenib
Vemurafenib

9.6 months
7.3 months

9.2 months
7.3 months

HR (95% CI): 0.68 (0.52-0.90); P=0.007

HR (95% CI): 0.70 (0.54-0.91); P=0.008
In this study, COMBO450 was generally well-tolerated, with a median duration of treatment of 51 weeks and median relative dose intensity for encorafenib and binimetinib of 100% and 99.6%, respectively. Grade 3/4 AEs that occurred in more than 5% of patients receiving COMBO450 were increased GGT (9%), increased blood CK (7%) and hypertension (6%). The incidence of selected any grade AEs of special interest, defined based on toxicities commonly associated with commercially available MEK+BRAF-inhibitor treatments for patients receiving COMBO450 included: rash (23%), pyrexia (18%), retinal pigment epithelial detachment (13%) and photosensitivity (5%). Full safety results of COLUMBUS Part 1 were presented at the 2016 Society for Melanoma Research Annual Congress.

COLUMBUS Part 2 was designed specifically to assess the contribution of binimetinib to the combination of binimetinib and encorafenib by reducing the dose of encorafenib to 300 mg in the combination arm to allow for a comparison of equal doses across arms. In COLUMBUS Part 2, the primary analysis compared PFS in patients treated with COMBO300 to patients treated with encorafenib 300 mg daily as a single agent.

About the Phase 3 COLUMBUS Study
The COLUMBUS trial, (NCT01909453), is a two-part, international, randomized, open label Phase 3 study evaluating the efficacy and safety of the combination of binimetinib plus encorafenib to vemurafenib and to encorafenib monotherapy in 921 patients with locally advanced, unresectable or metastatic melanoma with BRAFV600 mutation. Prior immunotherapy treatment was allowed. Over 200 sites across North America, Europe, South America, Africa, Asia and Australia participated in the study. Patients were randomized into two parts:

In Part 1, 577 patients were randomized 1:1:1 to receive COMBO450, 300 mg encorafenib alone, or 960 mg vemurafenib alone. The dose of encorafenib in the combination arm is 50% higher than the single agent maximum tolerated dose of 300 mg. A higher dose of encorafenib was possible due to improved tolerability when combined with binimetinib. The primary endpoint for the COLUMBUS trial was a PFS comparison of COMBO450 versus vemurafenib. PFS is determined based on tumor assessment (RECIST version 1.1 criteria) by a BICR. Secondary endpoints include a comparison of the PFS of encorafenib monotherapy to that of COMBO450 and a comparison of overall survival (OS) for COMBO450 to that of vemurafenib alone.
In Part 2, 344 patients were randomized 3:1 to receive COMBO300 or 300 mg encorafenib alone. Part 2 was designed to provide additional data to help evaluate the contribution of binimetinib to the combination of binimetinib and encorafenib. As the comparison of COMBO450 to encorafenib in Part 1 did not achieve statistical significance, analyses of other endpoints including the statistical analysis conducted in Part 2 is descriptive.
About Melanoma
Metastatic melanoma is the most serious and life-threatening type of skin cancer and is associated with low survival rates[1],[2]. There are about 200,000 new cases of melanoma diagnosed worldwide each year, approximately half of which have BRAF mutations, a key target in the treatment of metastatic melanoma[1],[3],[4].

About Binimetinib and Encorafenib
MEK and BRAF are key protein kinases in the MAPK signaling pathway (RAS-RAF-MEK-ERK). Research has shown this pathway regulates several key cellular activities including proliferation, differentiation, survival and angiogenesis. Inappropriate activation of proteins in this pathway has been shown to occur in many cancers, such as melanoma, colorectal and thyroid cancers. Binimetinib is a late-stage small molecule MEK inhibitor and encorafenib is a late-stage small molecule BRAF inhibitor, both of which target key enzymes in this pathway. Binimetinib and encorafenib are being studied in clinical trials in advanced cancer patients, including the Phase 3 BEACON CRC trial with encorafenib in combination with cetuximab with or without binimetinib in patients with BRAFV600E-mutant colorectal cancer.

Binimetinib and encorafenib are investigational medicines and are not currently approved in any country.

Array BioPharma retains exclusive rights to binimetinib and encorafenib in key markets including the U.S., Canada and Israel. Array has granted Ono Pharmaceutical exclusive rights to commercialize both products in Japan and South Korea and Pierre Fabre exclusive rights to commercialize both products in all other countries, including Europe, Asia and Latin America.