SummaryBackgroundPembrolizumab improved progression-free survival and overall survival versus ipilimumab in patients with advanced melanoma and is now a standard of care in the first-line setting. ...However, the optimal duration of anti-PD-1 administration is unknown. We present results from 5 years of follow-up of patients in KEYNOTE-006. MethodsKEYNOTE-006 was an open-label, multicentre, randomised, controlled, phase 3 study done at 87 academic institutions, hospitals, and cancer centres in 16 countries. Patients aged at least 18 years with Eastern Cooperative Oncology Group performance status of 0 or 1, ipilimumab-naive histologically confirmed advanced melanoma with known BRAFV600 status and up to one previous systemic therapy were randomly assigned (1:1:1) to intravenous pembrolizumab 10 mg/kg every 2 weeks or every 3 weeks or four doses of intravenous ipilimumab 3 mg/kg every 3 weeks. Treatments were assigned using a centralised, computer-generated allocation schedule with blocked randomisation within strata. Exploratory combination of data from the two pembrolizumab dosing regimen groups was not protocol-specified. Pembrolizumab treatment continued for up to 24 months. Eligible patients who discontinued pembrolizumab with stable disease or better after receiving at least 24 months of pembrolizumab or discontinued with complete response after at least 6 months of pembrolizumab and then progressed could receive an additional 17 cycles of pembrolizumab. Co-primary endpoints were overall survival and progression-free survival. Efficacy was analysed in all randomly assigned patients, and safety was analysed in all randomly assigned patients who received at least one dose of study treatment. Exploratory assessment of efficacy and safety at 5 years' follow-up was not specified in the protocol. Data cutoff for this analysis was Dec 3, 2018. Recruitment is closed; the study is ongoing. This study is registered with ClinicalTrials.gov, number NCT01866319. FindingsBetween Sept 18, 2013, and March 3, 2014, 834 patients were enrolled and randomly assigned to receive pembrolizumab (every 2 weeks, n=279; every 3 weeks, n=277), or ipilimumab (n=278). After a median follow-up of 57·7 months (IQR 56·7–59·2) in surviving patients, median overall survival was 32·7 months (95% CI 24·5–41·6) in the combined pembrolizumab groups and 15·9 months (13·3–22·0) in the ipilimumab group (hazard ratio HR 0·73, 95% CI 0·61–0·88, p=0·00049). Median progression-free survival was 8·4 months (95% CI 6·6–11·3) in the combined pembrolizumab groups versus 3·4 months (2·9–4·2) in the ipilimumab group (HR 0·57, 95% CI 0·48–0·67, p<0·0001). Grade 3–4 treatment-related adverse events occurred in 96 (17%) of 555 patients in the combined pembrolizumab groups and in 50 (20%) of 256 patients in the ipilimumab group; the most common of these events were colitis (11 2% vs 16 6%), diarrhoea (ten 2% vs seven 3%), and fatigue (four <1% vs three 1%). Any-grade serious treatment-related adverse events occurred in 75 (14%) patients in the combined pembrolizumab groups and in 45 (18%) patients in the ipilimumab group. One patient assigned to pembrolizumab died from treatment-related sepsis. InterpretationPembrolizumab continued to show superiority over ipilimumab after almost 5 years of follow-up. These results provide further support for use of pembrolizumab in patients with advanced melanoma. FundingMerck Sharp & Dohme.
Summary Background Patients with melanoma that progresses on ipilimumab and, if BRAFV600 mutant-positive, a BRAF or MEK inhibitor or both, have few treatment options. We assessed the efficacy and ...safety of two pembrolizumab doses versus investigator-choice chemotherapy in patients with ipilimumab-refractory melanoma. Methods We carried out a randomised phase 2 trial of patients aged 18 years or older from 73 hospitals, clinics, and academic medical centres in 12 countries who had confirmed progressive disease within 24 weeks after two or more ipilimumab doses and, if BRAFV600 mutant-positive, previous treatment with a BRAF or MEK inhibitor or both. Patients had to have resolution of all ipilimumab-related adverse events to grade 0–1 and prednisone 10 mg/day or less for at least 2 weeks, an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and at least one measurable lesion to be eligible. Using a centralised interactive voice response system, we randomly assigned (1:1:1) patients in a block size of six to receive intravenous pembrolizumab 2 mg/kg or 10 mg/kg every 3 weeks or investigator-choice chemotherapy (paclitaxel plus carboplatin, paclitaxel, carboplatin, dacarbazine, or oral temozolomide). Randomisation was stratified by ECOG performance status, lactate dehydrogenase concentration, and BRAFV600 mutation status. Individual treatment assignment between pembrolizumab and chemotherapy was open label, but investigators and patients were masked to assignment of the dose of pembrolizumab. We present the primary endpoint at the prespecified second interim analysis of progression-free survival in the intention-to-treat population. This study is registered with ClinicalTrials.gov , number NCT01704287 . The study is closed to enrolment but continues to follow up and treat patients. Findings Between Nov 30, 2012, and Nov 13, 2013, we enrolled 540 patients: 180 patients were randomly assigned to receive pembrolizumab 2 mg/kg, 181 to receive pembrolizumab 10 mg/kg, and 179 to receive chemotherapy. Based on 410 progression-free survival events, progression-free survival was improved in patients assigned to pembrolizumab 2 mg/kg (HR 0·57, 95% CI 0·45–0·73; p<0·0001) and those assigned to pembrolizumab 10 mg/kg (0·50, 0·39–0·64; p<0·0001) compared with those assigned to chemotherapy. 6-month progression-free survival was 34% (95% CI 27–41) in the pembrolizumab 2 mg/kg group, 38% (31–45) in the 10 mg/kg group, and 16% (10–22) in the chemotherapy group. Treatment-related grade 3–4 adverse events occurred in 20 (11%) patients in the pembrolizumab 2 mg/kg group, 25 (14%) in the pembrolizumab 10 mg/kg group, and 45 (26%) in the chemotherapy group. The most common treatment-related grade 3–4 adverse event in the pembrolizumab groups was fatigue (two 1% of 178 patients in the 2 mg/kg group and one <1% of 179 patients in the 10 mg/kg group, compared with eight 5% of 171 in the chemotherapy group). Other treatment-related grade 3–4 adverse events include generalised oedema and myalgia (each in two 1% patients) in those given pembrolizumab 2 mg/kg; hypopituitarism, colitis, diarrhoea, decreased appetite, hyponatremia, and pneumonitis (each in two 1%) in those given pembrolizumab 10 mg/kg; and anaemia (nine 5%), fatigue (eight 5%), neutropenia (six 4%), and leucopenia (six 4%) in those assigned to chemotherapy. Interpretation These findings establish pembrolizumab as a new standard of care for the treatment of ipilimumab-refractory melanoma. Funding Merck Sharp & Dohme.
Summary Background Previously, a study of ours showed that the combination of dabrafenib and trametinib improves progression-free survival compared with dabrafenib and placebo in patients with BRAF ...Val600Lys/Glu mutation-positive metastatic melanoma. The study was continued to assess the secondary endpoint of overall survival, which we report in this Article. Methods We did this double-blind phase 3 study at 113 sites in 14 countries. We enrolled previously untreated patients with BRAF Val600Glu or Val600Lys mutation-positive unresectable stage IIIC or stage IV melanoma. Participants were computer-randomised (1:1) to receive a combination of dabrafenib (150 mg orally twice daily) and trametinib (2 mg orally once daily), or dabrafenib and placebo. The primary endpoint was progression-free survival and overall survival was a secondary endpoint. This study is registered with ClinicalTrials.gov , number NCT01584648. Findings Between May 4, 2012, and Nov 30, 2012, we screened 947 patients for eligibility, of whom 423 were randomly assigned to receive dabrafenib and trametinib (n=211) or dabrafenib only (n=212). The final data cutoff was Jan 12, 2015, at which time 222 patients had died. Median overall survival was 25·1 months (95% CI 19·2–not reached) in the dabrafenib and trametinib group versus 18·7 months (15·2–23·7) in the dabrafenib only group (hazard ratio HR 0·71, 95% CI 0·55–0·92; p=0·0107). Overall survival was 74% at 1 year and 51% at 2 years in the dabrafenib and trametinib group versus 68% and 42%, respectively, in the dabrafenib only group. Based on 301 events, median progression-free survival was 11·0 months (95% CI 8·0–13·9) in the dabrafenib and trametinib group and 8·8 months (5·9–9·3) in the dabrafenib only group (HR 0·67, 95% CI 0·53–0·84; p=0·0004; unadjusted for multiple testing). Treatment-related adverse events occurred in 181 (87%) of 209 patients in the dabrafenib and trametinib group and 189 (90%) of 211 patients in the dabrafenib only group; the most common was pyrexia (108 patients, 52%) in the dabrafenib and trametinib group, and hyperkeratosis (70 patients, 33%) in the dabrafenib only group. Grade 3 or 4 adverse events occurred in 67 (32%) patients in the dabrafenib and trametinib group and 66 (31%) patients in the dabrafenib only group. Interpretation The improvement in overall survival establishes the combination of dabrafenib and trametinib as the standard targeted treatment for BRAF Val600 mutation-positive melanoma. Studies assessing dabrafenib and trametinib in combination with immunotherapies are ongoing. Funding GlaxoSmithKline.
Summary Background The anti-programmed-death-receptor-1 (PD-1) antibody pembrolizumab has shown potent antitumour activity at different doses and schedules in patients with melanoma. We compared the ...efficacy and safety of pembrolizumab at doses of 2 mg/kg and 10 mg/kg every 3 weeks in patients with ipilimumab-refractory advanced melanoma. Methods In an open-label, international, multicentre expansion cohort of a phase 1 trial, patients (aged ≥18 years) with advanced melanoma whose disease had progressed after at least two ipilimumab doses were randomly assigned with a computer-generated allocation schedule (1:1 final ratio) to intravenous pembrolizumab at 2 mg/kg every 3 weeks or 10 mg/kg every 3 weeks until disease progression, intolerable toxicity, or consent withdrawal. Primary endpoint was overall response rate (ORR) assessed with the Response Evaluation Criteria In Solid Tumors (RECIST, version 1.1) by independent central review. Analysis was done on the full-analysis set (all treated patients with measurable disease at baseline). This study is registered with ClinicalTrials.gov , number NCT01295827. Findings 173 patients received pembrolizumab 2 mg/kg (n=89) or 10 mg/kg (n=84). Median follow-up duration was 8 months. ORR was 26% at both doses—21 of 81 patients in the 2 mg/kg group and 20 of 76 in the 10 mg/kg group (difference 0%, 95% CI −14 to 13; p=0·96). Treatment was well tolerated, with similar safety profiles in the 2 mg/kg and 10 mg/kg groups and no drug-related deaths. The most common drug-related adverse events of any grade in the 2 mg/kg and 10 mg/kg groups were fatigue (29 33% vs 31 37%), pruritus (23 26% vs 16 19%), and rash (16 18% vs 15 18%). Grade 3 fatigue, reported in five (3%) patients in the 2 mg/kg pembrolizumab group, was the only drug-related grade 3 to 4 adverse event reported in more than one patient. Interpretation The results suggest that pembrolizumab at a dose of 2 mg/kg or 10 mg/kg every 3 weeks might be an effective treatment in patients for whom there are few effective treatment options. Funding Merck Sharp and Dohme.
Summary Background Dabrafenib plus trametinib treatment provides significant benefits over BRAF-inhibitor monotherapy in patients with BRAFV600E -mutant or BRAFV600K -mutant advanced melanoma; ...however, in many patients the disease progresses, leading to death. With many treatment options available, understanding clinical factors that predict long-term response and survival for treatments is important for optimisation of patient management. We aimed to identify clinical factors associated with long-term response and survival using pooled data from randomised trials of dabrafenib plus trametinib in patients with metastatic BRAF -mutant melanoma. Methods We did a retrospective individual data analysis based on all published randomised trials that included treatment-naive patients with BRAFV600E -mutant or BRAFV600K -mutant metastatic melanoma who received the approved dose of dabrafenib 150 mg twice daily plus trametinib 2 mg once daily. Data were pooled from patients in the BRF113220 (part C; March 26, 2010, to Jan 15, 2015), COMBI-d (May 4, 2012, to Jan 12, 2015), and COMBI-v (June 4, 2012, to March 13, 2015) randomised trials. Patients with untreated brain metastases were not permitted to enrol in these trials. Baseline factors, identified a priori based on known melanoma clinical or prognostic characteristics, were analysed for association with progression-free survival and overall survival using univariate and multivariate analyses and assessed for hierarchical effect on outcomes using regression tree analyses. We also analysed factors identified after baseline, on treatment, and at progression, for associations with survival after progression. The trials included in this analysis are registered with ClinicalTrials.gov : BRF113220, number NCT01072175 ; COMBI-d, number NCT01584648 ; COMBI-v, number NCT01597908. Findings 617 patients were included in this analysis with a median follow-up of 20·0 months (range 0−48·0, IQR 10·1−24·8); 396 patients had progression events (ie, disease progression or death) and 290 patients had died. Median progression-free survival (11·1 months 95% CI 9·7−12·9), median overall survival (25·6 months 23·1−34·3), 1-year progression-free survival (48% 44–52) and overall survival (74% 71–78), and 2-year progression-free survival (30% 26–34) and overall survival (53% 49–57) were consistent with those in the individual trials. Patients with normal lactate dehydrogenase (LDH) concentration and fewer than three organ sites containing metastases (n=237) had the longest 1-year progression-free survival (68% 95% CI 62–74) and overall survival (90% 87–94) and 2-year progression-free survival (46% 40–54) and overall survival (75% 70–81), whereas patients with LDH concentration at least two times the upper limit of normal (n=70) had the shortest 1-year progression-free survival (8% 3–19) and overall survival (40% 29–55) and 2-year progression-free survival (2% 0–13) and overall survival (7% 3–19). Of patients with disease progression (n=379), survival after progression was longest in those with progression in baseline or new non-CNS lesions (n=205; median 10·0 months 95% CI 7·9−12·0) and shortest in those with new CNS lesions or concurrent progression in baseline and new lesions (n=171; median 4·0 months 3·5−4·9). Interpretation Several patient and clinical characteristics at and after baseline are associated with outcomes with dabrafenib plus trametinib, and durable benefit is possible with targeted treatment in defined patient subsets. Funding Novartis.
Summary Background In the COMBI-v trial, patients with previously untreated BRAF Val600Glu or Val600Lys mutant unresectable or metastatic melanoma who were treated with the combination of dabrafenib ...and trametinib had significantly longer overall and progression-free survival than those treated with vemurafenib alone. Here, we present the effects of treatments on health-related quality of life (HRQoL), an exploratory endpoint in the COMBI-v study. Methods COMBI-v was an open-label, randomised phase 3 study in which 704 patients with metastatic melanoma with a BRAF Val600 mutation were randomly assigned (1:1) by an interactive voice response system to receive either a combination of dabrafenib (150 mg twice-daily) and trametinib (2 mg once-daily) or vemurafenib monotherapy (960 mg twice-daily) orally as first-line therapy. The primary endpoint was overall survival. In this pre-specified exploratory analysis, we prospectively assessed HRQoL in the intention-to-treat population with the European Organisation for Research and Treatment of Cancer quality of life (EORTC QLQ-C30), EuroQoL-5D (EQ-5D), and Melanoma Subscale of the Functional Assessment of Cancer Therapy—Melanoma (FACT-M), completed at baseline, during study treatment, at disease progression, and after progression. We used a mixed-model, repeated measures ANCOVA to assess differences in mean scores between groups with baseline score as covariate; all p-values are descriptive. The COMBI-v trial is registered with ClinicalTrials.gov , number NCT01597908 , and is ongoing for the primary endpoint, but is not recruiting patients. Findings From June 4, 2012, to Oct 7, 2013, 1645 patients at 193 centres worldwide were screened for eligibility, and 704 patients were randomly assigned to dabrafenib plus trametinib (n=352) or vemurafenib (n=352). Questionnaire completion rates for both groups were high (>95% at baseline, >80% at follow-up assessments, and >70% at disease progression) with similar HRQoL and symptom scores reported at baseline in both treatment groups for all questionnaires. Differences in mean scores between treatment groups were significant and clinically meaningful in favour of the combination compared with vemurafenib monotherapy for most domains across all three questionnaires during study treatment and at disease progression, including EORTC QLQ-C30 global health (7·92, 7·62, 6·86, 7·47, 5·16, 7·56, and 7·57 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; p<0·001 for all assessments except p=0·005 at week 40), EORTC QLQ-C30 pain (–13·20, −8·05, −8·82, −12·69, −12·46, −11·41, and −10·57 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; all p<0·001), EQ-5D thermometer scores (7·96, 8·05, 6·83, 11·53, 7·41, 9·08, and 10·51 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; p<0·001 for all assessments except p=0·006 at week 32), and FACT-M Melanoma Subscale score (3·62, 2·93, 2·45, 3·39, 2·85, 3·00, and 3·68 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; all p<0·001). Interpretation From the patient's perspective, which integrates not only survival advantage but also disease-associated and adverse-event-associated symptoms, treatment with the combination of a BRAF inhibitor plus a MEK inhibitor (dabrafenib plus trametinib) adds a clear benefit over monotherapy with the BRAF inhibitor vemurafenib and supports the combination therapy as standard of care in this population. Funding GlaxoSmithKline.
Summary Background The combination of cobimetinib with vemurafenib improves progression-free survival compared with placebo and vemurafenib in previously untreated patients with BRAFV600 -mutant ...advanced melanoma, as previously reported in the coBRIM study. In this Article, we report updated efficacy results, including overall survival and safety after longer follow-up, and selected biomarker correlative studies. Methods In this double-blind, randomised, placebo-controlled, multicentre study, adult patients (aged ≥18 years) with histologically confirmed BRAFV600 mutation-positive unresectable stage IIIC or stage IV melanoma were randomly assigned (1:1) using an interactive response system to receive cobimetinib (60 mg once daily for 21 days followed by a 7-day rest period in each 28-day cycle) or placebo, in combination with oral vemurafenib (960 mg twice daily). Progression-free and overall survival were primary and secondary endpoints, respectively; all analyses were done on the intention-to-treat population. This study is registered with ClinicalTrials.gov , number NCT01689519 , and is ongoing but no longer recruiting participants. Findings Between Jan 8, 2013, and Jan 31, 2014, 495 eligible adult patients were enrolled and randomly assigned to the cobimetinib plus vemurafenib group (n=247) or placebo plus vemurafenib group (n=248). At a median follow-up of 14·2 months (IQR 8·5–17·3), the updated investigator-assessed median progression-free survival was 12·3 months (95% CI 9·5–13·4) for cobimetinib and vemurafenib versus 7·2 months (5·6–7·5) for placebo and vemurafenib (HR 0·58 95% CI 0·46–0·72, p<0·0001). The final analysis for overall survival occurred when 255 (52%) patients had died (Aug 28, 2015). Median overall survival was 22·3 months (95% CI 20·3–not estimable) for cobimetinib and vemurafenib versus 17·4 months (95% CI 15·0–19·8) for placebo and vemurafenib (HR 0·70, 95% CI 0·55–0·90; p=0·005). The safety profile for cobimetinib and vemurafenib was tolerable and manageable, and no new safety signals were observed with longer follow-up. The most common grade 3–4 adverse events occurring at a higher frequency in patients in the cobimetinib and vemurafenib group compared with the vemurafenib group were γ-glutamyl transferase increase (36 15% in the cobimetinib and vemurafenib group vs 25 10% in the placebo and vemurafenib group), blood creatine phosphokinase increase (30 12% vs one <1%), and alanine transaminase increase (28 11% vs 15 6%). Serious adverse events occurred in 92 patients (37%) in the cobimetinib and vemurafenib group and 69 patients (28%) in the vemurafenib group. Pyrexia (six patients 2%) and dehydration (five patients 2%) were the most common serious adverse events reported in the cobimetinib and vemurafenib group. A total of 259 patients have died: 117 (47%) in the cobimetinib and vemurafenib group and 142 (58%) in the vemurafenib group. The primary cause of death was disease progression in most patients: 109 (93%) of 117 in the cobimetinib and vemurafenib group and 133 (94%) of 142 in the vemurafenib group. Interpretation These data confirm the clinical benefit of cobimetinib combined with vemurafenib and support the use of the combination as a standard first-line approach to improve survival in patients with advanced BRAFV600 -mutant melanoma. Funding F Hoffmann-La Roche–Genentech.
Summary Background In the BRIM-3 trial, vemurafenib was associated with risk reduction versus dacarbazine of both death and progression in patients with advanced BRAFV600 mutation-positive melanoma. ...We present an extended follow-up analysis of the total population and in the BRAFV600E and BRAFV600K mutation subgroups. Methods Patients older than 18 years, with treatment-naive metastatic melanoma and whose tumour tissue was positive for BRAFV600 mutations were eligible. Patients also had to have a life expectancy of at least 3 months, an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and adequate haematological, hepatic, and renal function. Patients were randomly assigned by interactive voice recognition system to receive either vemurafenib (960 mg orally twice daily) or dacarbazine (1000 mg/m2 of body surface area intravenously every 3 weeks). Coprimary endpoints were overall survival and progression-free survival, analysed in the intention-to-treat population (n=675), with data censored at crossover. A sensitivity analysis was done. This trial is registered with ClinicalTrials.gov , NCT01006980. Findings 675 eligible patients were enrolled from 104 centres in 12 countries between Jan 4, 2010, and Dec 16, 2010. 337 patients were randomly assigned to receive vemurafenib and 338 to receive dacarbazine. Median follow-up was 12·5 months (IQR 7·7–16·0) on vemurafenib and 9·5 months (3·1–14·7) on dacarbazine. 83 (25%) of the 338 patients initially randomly assigned to dacarbazine crossed over from dacarbazine to vemurafenib. Median overall survival was significantly longer in the vemurafenib group than in the dacarbazine group (13·6 months 95% CI 12·0–15·2 vs 9·7 months 7·9–12·8; hazard ratio HR 0·70 95% CI 0·57–0·87; p=0·0008), as was median progression-free survival (6·9 months 95% CI 6·1–7·0 vs 1·6 months 1·6–2·1; HR 0·38 95% CI 0·32–0·46; p<0·0001). For the 598 (91%) patients with BRAFV600E disease, median overall survival in the vemurafenib group was 13·3 months (95% CI 11·9–14·9) compared with 10·0 months (8·0–14·0) in the dacarbazine group (HR 0·75 95% CI 0·60–0·93; p=0·0085); median progression-free survival was 6·9 months (95% CI 6·2–7·0) and 1·6 months (1·6–2·1), respectively (HR 0·39 95% CI 0·33–0·47; p<0·0001). For the 57 (9%) patients with BRAFV600K disease, median overall survival in the vemurafenib group was 14·5 months (95% CI 11·2–not estimable) compared with 7·6 months (6·1–16·6) in the dacarbazine group (HR 0·43 95% CI 0·21–0·90; p=0·024); median progression-free survival was 5·9 months (95% CI 4·4–9·0) and 1·7 months (1·4–2·9), respectively (HR 0·30 95% CI 0·16–0·56; p<0·0001). The most frequent grade 3–4 events were cutaneous squamous-cell carcinoma (65 19% of 337 patients) and keratoacanthomas (34 10%), rash (30 9%), and abnormal liver function tests (38 11%) in the vemurafenib group and neutropenia (26 9% of 287 patients) in the dacarbazine group. Eight (2%) patients in the vemurafenib group and seven (2%) in the dacarbazine group had grade 5 events. Interpretation Inhibition of BRAF with vemurafenib improves survival in patients with the most common BRAFV600E mutation and in patients with the less common BRAFV600K mutation. Funding F Hoffmann-La Roche-Genentech.
Summary Background Addition of a MEK inhibitor to a BRAF inhibitor enhances tumour growth inhibition, delays acquired resistance, and abrogates paradoxical activation of the MAPK pathway in ...preclinical models of BRAF -mutated melanoma. We assessed the safety and efficacy of combined BRAF inhibition with vemurafenib and MEK inhibition with cobimetinib in patients with advanced BRAF -mutated melanoma. Methods We undertook a phase 1b study in patients with advanced BRAFV600 -mutated melanoma. We included individuals who had either recently progressed on vemurafenib or never received a BRAF inhibitor. In the dose-escalation phase of our study, patients received vemurafenib 720 mg or 960 mg twice a day continuously and cobimetinib 60 mg, 80 mg, or 100 mg once a day for either 14 days on and 14 days off (14/14), 21 days on and 7 days off (21/7), or continuously (28/0). The primary endpoint was safety of the drug combination and to identify dose-limiting toxic effects and the maximum tolerated dose. Efficacy was a key secondary endpoint. All patients treated with vemurafenib and cobimetinib were included in safety and efficacy analyses (intention-to-treat). The study completed accrual and all analyses are final. This study is registered with ClinicalTrials.gov , number NCT01271803. Findings 129 patients were treated at ten dosing regimens combining vemurafenib and cobimetinib: 66 had recently progressed on vemurafenib and 63 had never received a BRAF inhibitor. Dose-limiting toxic effects arose in four patients. One patient on a schedule of vemurafenib 960 mg twice a day and cobimetinib 80 mg once a day 14/14 had grade 3 fatigue for more than 7 days; one patient on a schedule of vemurafenib 960 mg twice a day and cobimetinib 60 mg once a day 21/7 had a grade 3 prolongation of QTc; and two patients on a schedule of vemurafenib 960 mg twice a day and cobimetinib 60 mg 28/0 had dose-limiting toxic effects—one developed grade 3 stomatitis and fatigue and one developed arthralgia and myalgia. The maximum tolerated dose was established as vemurafenib 960 mg twice a day in combination with cobimetinib 60 mg 21/7. Across all dosing regimens, the most common adverse events were diarrhoea (83 patients, 64%), non-acneiform rash (77 patients, 60%), liver enzyme abnormalities (64 patients, 50%), fatigue (62 patients, 48%), nausea (58 patients, 45%), and photosensitivity (52 patients, 40%). Most adverse events were mild-to-moderate in severity. The most common grade 3 or 4 adverse events were cutaneous squamous-cell carcinoma (12 patients, 9%; all grade 3), raised amounts of alkaline phosphatase (11 patients, 9%), and anaemia (nine patients, 7%). Confirmed objective responses were recorded in ten (15%) of 66 patients who had recently progressed on vemurafenib, with a median progression-free survival of 2·8 months (95% CI 2·6–3·4). Confirmed objective responses were noted in 55 (87%) of 63 patients who had never received a BRAF inhibitor, including six (10%) who had a complete response; median progression-free survival was 13·7 months (95% CI 10·1–17·5). Interpretation The combination of vemurafenib and cobimetinib was safe and tolerable when administered at the respective maximum tolerated doses. The combination has promising antitumour activity and further clinical development is warranted in patients with advanced BRAFV600 -mutated melanoma, particularly in those who have never received a BRAF inhibitor; confirmatory clinical testing is ongoing. Funding F Hoffmann-La Roche/Genentech.