A Study Evaluating the Combination of Encorafenib and Cetuximab Versus Irinotecan/Cetuximab or Infusional 5-fluorouracil (5-FU)/Folinic Acid (FA)/Irinotecan (FOLFIRI)/Cetuximab in Chinese Patients With BRAF V600E Mutant Metastatic Colorectal Cancer.

Safety Lead-in Phase: Type and severity of Adverse Events (AEs) and Serious Adverse Events (SAEs) according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version 4.03

Time frame: Informed consent through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Incidence of treatment-emergent adverse events (TEAEs) related to notable or abnormal changes from baseline of physical examinations

Standard physical examinations on cardiovascular, respiratory, gastrointestinal, dermatological, ophthalmological and neurological systems will be performed and will be evaluated based on normal/abnormal and clinical significance observations. Number of participants with TEAEs related to abnormal or clinical significance observations to the physical examinations after the start of study drug will be reported.

Time frame: Day 1 through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Incidence of treatment-emergent adverse events (TEAEs) related to notable or abnormal changes in vital signs from baseline of vital sign examinations.

Clinically notable elevated values: Systolic blood pressure (BP): ≥ 160 mmHg and an increase ≥ 20 mmHg from baseline; Diastolic BP: ≥ 100 mmHg and an increase ≥ 15 mmHg from baseline; Heart rate : ≥ 120 beats/min (bpm) with increase from baseline of ≥ 15 bpm; Weight (kg) increase from baseline of ≥ 10%; Body temperature(°C) ≥ 37.5°C). Clinically notable low values: Systolic BP: ≤ 90 mmHg with decrease from baseline of ≥ 20 mmHg; Diastolic BP: ≤ 50 mmHg with decrease from baseline of ≥ 15 mmHg; Heart rate: ≤ 50 bpm with decrease from baseline of ≥ 15 bpm; Weight: ≥ 20% decrease from baseline; Body temperature \[°C\]: ≤ 36 °C. Number of participants with TEAEs related to notable changes to the vital signs after the start of study drug will be reported.

Time frame: Day 1 through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Incidence of treatment-emergent adverse events (TEAEs) related to notable or abnormal changes from baseline of 12-lead electrocardiograms (ECGs)

12-lead ECGs will be obtained using an internationally recognized 12-lead cardiograph. Clinically notable ECG values: QT (ms) and QT interval (ms) corrected for heart rate using Fridericia's formula (QTcF) intervals (ms) : increase from baseline \> 30 ms; increase from baseline \> 60 ms, new \> 450 ms, new \> 480 ms, new \> 500 ms. Heart rate (beats/min) : increase from baseline \> 25% to a value \> 100 bpm, decrease from baseline \> 25% and to a value \< 50 bpm. Number of participants with TEAEs related to abnormal or notable changes to ECG parameters after the start of study drug will be reported.

Time frame: Day 1 through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Incidence of treatment-emergent adverse events (TEAEs) related to notable changes in clinical safety laboratory parameters from baseline.

Number of participants with clinically notable shift from baseline in laboratory parameter values based on national cancer institute common terminology criteria (NCI-CTCAE) grade, Version 4.03 were graded from Grades 1 to 5. Grade 1: Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention not indicated. Grade 2: Moderate; minimal, local or noninvasive intervention indicated. Grade 3: Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated. Grade 4: Life-threatening consequences; urgent intervention indicated. Grade 5: Death. Clinically notable shift is defined as a worsening from baseline by at least 2 grades, or to grade 3 or above.

Time frame: Day 1 through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Incidence of development of of keratoacanthoma and/or squamous cell carcinoma and new primary melanoma by dermatological examinations

This is to monitor for the possible development of keratoacanthoma and/or squamous cell carcinoma and new primary melanoma, as these have been reported to occur with selective BRAF inhibitor treatment. This assessment will be performed at screening and every 8 weeks from Cycle 1 Day 1 (i.e. on Day 1 of Cycles 1, 3, 5, 7…), the end of treatment visit and the 30-day safety follow up visit.

Time frame: Screening (Day -28 to -1) through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Performance status assessment using the Eastern Co-operative Oncology Group (ECOG) performance status scale

Scale with a range from 0 to 5 with lower score mean a lower functional impairment, 5 corresponding to death

Time frame: Screening (Day -28 to -1) through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Incidence of dose interruptions, dose modifications and discontinuations due to adverse events (AEs)

Time frame: Day 1 until end of treatment, approximately 1 year

Safety Lead-in Phase: Plasma concentrations of encorafenib

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase: Serum concentrations of cetuximab

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase; Pharmacokinetic (PK) parameter derived from plasma concentration of encorafenib area under curve (AUC) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase: Pharmacokinetic (PK) parameter derived from serum concentration of cetuximab area under curve (AUC) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase: Pharmacokinetic (PK) parameter derived from plasma concentration of encorafenib minimum concentration (Cmin) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase: Pharmacokinetic (PK) parameter derived from serum concentration of cetuximab minimum concentration (Cmin) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase: Pharmacokinetic (PK) parameter derived from plasma concentration of encorafenib maximum concentration (Cmax) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase: Pharmacokinetic (PK) parameter derived from serum concentration of cetuximab maximum concentration (Cmax) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Safety Lead-in Phase: Objective response rate (ORR)

Objective response rate (ORR) defined as the proportion of participants with a best overall best response of either complete response (CR) or partial response (PR) as determined by Blinded (to treatment received) Independent Central Review (BICR) and investigator assessment per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1

Time frame: Day 1 through to study completion, approximately from 18 to 35 months

Safety Lead-in Phase: Duration of Response (DOR) (months); defined for responders complete response (CR) or partial response (PR) only, is duration of time from the date of the first documented response to the earliest date of disease progression

Duration of response, defined as the time from first documented response (complete response or partial response) to the earliest date of disease progression as determined by Blinded (to treatment received) Independent Central Review (BICR) and investigator assessment per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1, or death due to underlying disease.

Time frame: Day 1 through to study completion, approximately from 18 to 35 months

Randomized Phase 2: Progression-free survival (PFS)

Progression-free survival defined as the interval of time between the date of randomization to the earliest date of disease progression, as determined by investigator assessment per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, or death due to any cause.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Overall Response Rate (ORR)

Overall response rate (for confirmed and unconfirmed responses) defined as the proportion of participants with a confirmed (resp. unconfirmed) best overall response of either complete response or partial response, as determined by Blinded (to treatment received) Independent Central Review (BICR) and investigator assessment per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Duration of Response (DOR)

Duration of response defined as the time from the date of the first documented response (complete response or partial response) to the earliest date of disease progression, as determined by Blinded (to treatment received) Independent Central Review (BICR) and investigator assessment per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, or death due to any cause

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Disease control rate (DCR)

Disease control rate (DCR), defined as the proportion of participants with a best overall response of either complete response, partial response or stable disease (SD), as determined by Blinded (to treatment received) Independent Central Review (BICR) and investigator assessment per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Time to Response (TTR)

Time to Response (for confirmed and unconfirmed responses) is defined as the time between date of randomization until first documented response of complete response (CR) or partial response (PR).

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Overall Survival (OS)

Overall survival is defined as time from randomization until date of death due to any cause

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Type and severity of adverse events (AEs) and serious adverse events (SAEs) according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version 4.03

Time frame: Informed consent date through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Incidence of treatment-emergent adverse events (TEAEs) related to notable or abnormal changes from baseline of physical examinations

Standard physical examinations on cardiovascular, respiratory, gastrointestinal, dermatological, ophthalmological and neurological systems will be performed and will be evaluated based on normal/abnormal and clinical significance observations. Number of participants with TEAEs related to abnormal or clinical significance observations to the physical examinations after the start of study drug will be reported

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Incidence of treatment-emergent adverse events (TEAEs) related to notable changes in vital signs from baseline.

Clinically notable elevated values: Systolic blood pressure (BP): ≥ 160 mmHg and an increase ≥ 20 mmHg from baseline; Diastolic BP: ≥ 100 mmHg and an increase ≥ 15 mmHg from baseline; Heart rate : ≥ 120 beats/min (bpm) with increase from baseline of ≥ 15 bpm; Weight (kg) increase from baseline of ≥ 10%; Body temperature(°C) ≥ 37.5°C). Clinically notable low values: Systolic BP: ≤ 90 mmHg with decrease from baseline of ≥ 20 mmHg; Diastolic BP: ≤ 50 mmHg with decrease from baseline of ≥ 15 mmHg; Heart rate: ≤ 50 bpm with decrease from baseline of ≥ 15 bpm; Weight: ≥ 20% decrease from baseline; Body temperature \[°C\]: ≤ 36 °C. Number of participants with TEAEs related to notable changes to the vital signs after the start of study drug will be reported.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Incidence of treatment-emergent adverse events (TEAEs) related to notable or abnormal changes to electrocardiogram evaluations from baseline

12-lead ECGs will be obtained using an internationally recognized 12-lead cardiograph. Clinically notable ECG values: QT (ms) and QT interval (ms) corrected for heart rate using Fridericia's formula (QTcF) intervals (ms): increase from baseline \> 30 ms; increase from baseline \> 60 ms, new \> 450 ms, new \> 480 ms, new \> 500 ms; Heart rate (beats/min): increase from baseline \> 25% to a value \> 100 bpm, decrease from baseline \> 25% and to a value \< 50 bpm. Number of participants with TEAEs related to abnormal or notable changes to ECG parameters after the start of study drug will be reported.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Incidence of treatment-emergent adverse events (TEAEs) related to notable changes in clinical safety laboratory parameters from baseline.

Number of participants with clinically notable shift from baseline in laboratory parameter values based on national cancer institute common terminology criteria (NCI-CTCAE) grade, Version 4.03 were graded from Grades 1 to 5. Grade 1: Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention not indicated. Grade 2: Moderate; minimal, local or noninvasive intervention indicated. Grade 3: Severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated. Grade 4: Life-threatening consequences; urgent intervention indicated. Grade 5: Death. Clinically notable shift is defined as a worsening from baseline by at least 2 grades, or to grade 3 or above.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Incidence of development of keratoacanthoma and/or squamous cell carcinoma and new primary melanoma by dermatological examinations

This is to monitor for the possible development of keratoacanthoma and/or squamous cell carcinoma and new primary melanoma, as these have been reported to occur with selective BRAF inhibitor treatment. This assessment will be performed at screening and every 8 weeks from Cycle 1 Day 1 (i.e. on Day 1 of Cycles 1, 3, 5, 7…), the end of treatment visit and the 30-day safety follow up visit.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: To determine the performance status using the Eastern Co-operative Oncology Group (ECOG) performance status scale.

Scale with a range from 0 to 5 with lower score mean a lower functional impairment, 5 corresponding to death

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: To determine if there is any change from baseline in the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire for Cancer Patients (EORTC QLQ-C30) questionnaire scores

EORTC QLQ-C30 consist of nine multi-item scales: five functional scales (physical, role, cognitive, emotional and social); three symptom scales (fatigue, pain, nausea and vomiting); and a global health and Quality of Life (QoL) scale. Each scale in the questionnaire will be scored (0 to 100). High scores represents a high health/quality of life

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: To determine if there is any change from baseline in the European Quality of Life-5 Dimensions-5 Levels (EQ-5D-5L) questionnaire scores.

EQ-5D-5L consists of the EQ-5D descriptive system and the EQ visual analogue scale (VAS). The descriptive system has five dimension (mobility, self-care, usual activities, pain/discomfort and anxiety/depression), each is rated according to a five-point verbal rating scale (VRS): 1. no problems, 2. slight problems, 3. moderate problems, 4. severe problems and 5. extreme problems) and translated into a five-digit number that describes the participant's health state.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: To determine if there is any change from baseline in the Functional Assessment of Cancer Therapy-Colon Cancer (FACT-C) questionnaire scores

FACT-C is a validated quality of life questionnaire for patient reported outcome assessment. FACT-C consists of 36 items, presented on a five-point Likert scale, in four domains of well-being (physical, emotional, social and functional) and the Colorectal Cancer Subscale. Higher score reflects a better quality of life.

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: To determine if there is any changes in the Patient Global Impression of Change (PGIC) questionnaire scores.

PGIC will ask participants to evaluate their CRC symptoms since starting study intervention according to a seven-point verbal rating scale (VRS): 1. very much improved, 2. much improved, 3. minimally improved, 4. no change, 5. minimally worse, 6. much worse, 7. very much worse

Time frame: Day 1 through to study completion, approximately from 12 to 29 months

Randomized Phase 2: Plasma concentrations of encorafenib

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2: Serum concentrations of cetuximab

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2; Pharmacokinetic (PK) parameter derived from plasma concentration of encorafenib area under curve (AUC) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2: Pharmacokinetic (PK) parameter derived from serum concentration of cetuximab area under curve (AUC) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2: Pharmacokinetic (PK) parameter derived from plasma concentration of encorafenib minimum concentration (Cmin) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2: Pharmacokinetic (PK) parameter derived from serum concentration of cetuximab minimum concentration (Cmin) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2: Pharmacokinetic (PK) parameter derived from plasma concentration of encorafenib maximum concentration (Cmax) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2: Pharmacokinetic (PK) parameter derived from serum concentration of cetuximab maximum concentration (Cmax) in Chinese participants

Time frame: Day 1 of Cycles 1 and 2; Each cycle = 28 days

Randomized Phase 2: Population pharmacokinetic (PK) analysis using the ARRAY 818 302 study PK data

Time frame: Day 1 through to study completion, approximately from 12 to 29 months