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Pembrolizumab 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. KEYNOTE-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. Between 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. Pembrolizumab 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. Merck Sharp & Dohme.

Immunotherapy combination treatments can improve patient outcomes. Epacadostat, an IDO1 selective inhibitor, and pembrolizumab, a PD-1 inhibitor, showed promising antitumour activity in the phase 1–2 ECHO-202/KEYNOTE-037 study in advanced melanoma. In this trial, we aimed to compare progression-free survival and overall survival in patients with unresectable stage III or IV melanoma receiving epacadostat plus pembrolizumab versus placebo plus pembrolizumab. In this international, randomised, placebo-controlled, double-blind, parallel-group, phase 3 trial, eligible participants were aged 18 years or older, with unresectable stage III or IV melanoma previously untreated with PD-1 or PD-L1 checkpoint inhibitors, an ECOG performance status of 0 or 1, and had a known BRAFV600 mutant status or consented to BRAFV600 mutation testing during screening. Patients were stratified by PD-L1 expression and BRAFV600 mutation status and randomly assigned (1:1) through a central interactive voice and integrated web response system to receive epacadostat 100 mg orally twice daily plus pembrolizumab 200 mg intravenously every 3 weeks or placebo plus pembrolizumab for up to 2 years. We used block randomisation with a block size of four in each stratum. Primary endpoints were progression-free survival and overall survival in the intention-to-treat population. The safety analysis population included randomly assigned patients who received at least one dose of study treatment. The study was stopped after the second interim analysis; follow-up for safety is ongoing. This study is registered with ClinicalTrials.gov, number NCT02752074. Between June 21, 2016, and Aug 7, 2017, 928 patients were screened and 706 patients were randomly assigned to receive epacadostat plus pembrolizumab (n=354) or placebo plus pembrolizumab (n=352). Median follow-up was 12·4 months (IQR 10·3–14·5). No significant differences were found between the treatment groups for progression-free survival (median 4·7 months, 95% CI 2·9–6·8, for epacadostat plus pembrolizumab vs 4·9 months, 2·9–6·8, for placebo plus pembrolizumab; hazard ratio [HR] 1·00, 95% CI 0·83–1·21; one-sided p=0·52) or overall survival (median not reached in either group; epacadostat plus pembrolizumab vs placebo plus pembrolizumab: HR 1·13, 0·86–1·49; one-sided p=0·81). The most common grade 3 or worse treatment-related adverse event was lipase increase, which occurred in 14 (4%) of 353 patients receiving epacadostat plus pembrolizumab and 11 (3%) of 352 patients receiving placebo plus pembrolizumab. Treatment-related serious adverse events were reported in 37 (10%) of 353 patients receiving epacadostat plus pembrolizumab and 32 (9%) of 352 patients receiving placebo plus pembrolizumab. There were no treatment-related deaths in either treatment group. Epacadostat 100 mg twice daily plus pembrolizumab did not improve progression-free survival or overall survival compared with placebo plus pembrolizumab in patients with unresectable or metastatic melanoma. The usefulness of IDO1 inhibition as a strategy to enhance anti-PD-1 therapy activity in cancer remains uncertain. Incyte Corporation, in collaboration with Merck Sharp & Dohme.

Previously reported results from the phase 3 CheckMate 067 trial showed a significant improvement in objective responses, progression-free survival, and overall survival with nivolumab plus ipilimumab or nivolumab alone compared with ipilimumab alone in patients with advanced melanoma. The aim of this report is to provide 4-year updated efficacy and safety data from this study. In this phase 3 trial, eligible patients were aged 18 years or older with previously untreated, unresectable, stage III or stage IV melanoma, known BRAFV600 mutation status, and an Eastern Cooperative Oncology Group performance status of 0 or 1. Patients were randomly assigned 1:1:1 to receive intravenous nivolumab 1 mg/kg plus ipilimumab 3 mg/kg every 3 weeks for four doses, followed by nivolumab 3 mg/kg every 2 weeks, or nivolumab 3 mg/kg every 2 weeks plus placebo, or ipilimumab 3 mg/kg every 3 weeks for four doses plus placebo. Randomisation was done via an interactive voice response system with a permuted block schedule (block size of six) and stratification by PD-L1 status, BRAF mutation status, and metastasis stage. The patients, investigators, study site staff, and study funder were masked to the study drug administered. The co-primary endpoints were progression-free survival and overall survival. Efficacy analyses were done on the intention-to-treat population, whereas safety was assessed in all patients who received at least one dose of study drug. The results presented in this report reflect the 4-year update of the ongoing study with a database lock date of May 10, 2018. This study is registered with ClinicalTrials.gov, number NCT01844505. Between July 3, 2013, and March 31, 2014, 945 patients were enrolled and randomly assigned to nivolumab plus ipilimumab (n=314), nivolumab (n=316), or ipilimumab (n=315). Median follow-up was 46·9 months (IQR 10·9–51·8) in the nivolumab plus ipilimumab group, 36·0 months (10·5–51·4) in the nivolumab group, and 18·6 months (7·6–49·5) in the ipilimumab group. At a minimum follow-up of 48 months from the date that the final patient was enrolled and randomised, median overall survival was not reached (95% CI 38·2–not reached) in the nivolumab plus ipilimumab group, 36·9 months (28·3–not reached) in the nivolumab group, and 19·9 months (16·9–24·6) in the ipilimumab group. The hazard ratio for death for the combination versus ipilimumab was 0·54 (95% CI 0·44–0·67; p<0·0001) and for nivolumab versus ipilimumab was 0·65 (0·53–0·79; p<0·0001). Median progression-free survival was 11·5 months (95% CI 8·7–19·3) in the nivolumab plus ipilimumab group, 6·9 months (5·1–10·2) in the nivolumab group, and 2·9 months (2·8–3·2) in the ipilimumab group. The hazard ratio for progression-free survival for the combination versus ipilimumab was 0·42 (95% CI 0·35–0·51; p<0·0001) and for nivolumab versus ipilimumab was 0·53 (0·44–0·64; p<0·0001). Treatment-related grade 3–4 adverse events were reported in 185 (59%) of 313 patients who received nivolumab plus ipilimumab, 70 (22%) of 313 who received nivolumab, and 86 (28%) of 311 who received ipilimumab. The most common treatment-related grade 3 adverse events were diarrhoea in the nivolumab plus ipilimumab group (29 [9%] of 313) and in the nivolumab group (nine [3%] of 313) and colitis in the ipilimumab group (23 [7%] of 311); the most common grade 4 adverse event in all three groups was increased lipase (15 [5%] of 313 in the combination group, ten [3%] of 313 in the nivolumab group, and four [1%] of 311 in the ipilimumab group). Serious adverse events were not analysed for the 4-year follow-up. In total for the study, there were four treatment-related deaths: two in the nivolumab plus ipilimumab group (one cardiomyopathy and one liver necrosis), one in the nivolumab group (neutropenia), and one in the ipilimumab group (colon perforation). No additional treatment-related deaths have occurred since the previous (3-year) analysis. The results of this analysis at 4 years of follow-up show that a durable, sustained survival benefit can be achieved with first-line nivolumab plus ipilimumab or nivolumab alone in patients with advanced melanoma. Bristol-Myers Squibb.

Patients with resected stage IIB/C melanoma have high recurrence risk, similar to those with resected stage IIIA/B disease. The phase 3, double-blind CheckMate 76K trial assessed 790 patients with resected stage IIB/C melanoma randomized 2:1 (stratified by tumor category) to nivolumab 480 mg or placebo every 4 weeks for 12 months. The primary endpoint was investigator-assessed recurrence-free survival (RFS). Secondary endpoints included distant metastasis-free survival (DMFS) and safety. At 7.8 months of minimum follow-up, nivolumab significantly improved RFS versus placebo (hazard ratio (HR) = 0.42; 95% confidence interval (CI): 0.30–0.59; P  < 0.0001), with 12-month RFS of 89.0% versus 79.4% and benefit observed across subgroups; DMFS was also improved (HR = 0.47; 95% CI: 0.30–0.72). Treatment-related grade 3/4 adverse events occurred in 10.3% (nivolumab) and 2.3% (placebo) of patients. One treatment-related death (0.2%) occurred with nivolumab. Nivolumab is an effective and generally well-tolerated adjuvant treatment in patients with resected stage IIB/C melanoma. ClinicalTrials.gov identifier: NCT04099251 . In this pre-specified interim analysis, patients with resected stage IIB/C melanoma who received adjuvant nivolumab had significantly prolonged recurrence-free survival compared to placebo-treated patients, providing another treatment option for this population.

Ipilimumab is an approved treatment for patients with advanced melanoma. We aimed to assess ipilimumab as adjuvant therapy for patients with completely resected stage III melanoma at high risk of recurrence. We did a double-blind, phase 3 trial in patients with stage III cutaneous melanoma (excluding lymph node metastasis ≤1 mm or in-transit metastasis) with adequate resection of lymph nodes (ie, the primary cutaneous melanoma must have been completely excised with adequate surgical margins) who had not received previous systemic therapy for melanoma from 91 hospitals located in 19 countries. Patients were randomly assigned (1:1), centrally by an interactive voice response system, to receive intravenous infusions of 10 mg/kg ipilimumab or placebo every 3 weeks for four doses, then every 3 months for up to 3 years. Using a minimisation technique, randomisation was stratified by disease stage and geographical region. The primary endpoint was recurrence-free survival, assessed by an independent review committee, and analysed by intention to treat. Enrollment is complete but the study is ongoing for follow-up for analysis of secondary endpoints. This trial is registered with EudraCT, number 2007-001974-10, and ClinicalTrials.gov, number NCT00636168. Between July 10, 2008, and Aug 1, 2011, 951 patients were randomly assigned to ipilimumab (n=475) or placebo (n=476), all of whom were included in the intention-to-treat analyses. At a median follow-up of 2·74 years (IQR 2·28–3·22), there were 528 recurrence-free survival events (234 in the ipilimumab group vs 294 in the placebo group). Median recurrence-free survival was 26·1 months (95% CI 19·3–39·3) in the ipilimumab group versus 17·1 months (95% CI 13·4–21·6) in the placebo group (hazard ratio 0·75; 95% CI 0·64–0·90; p=0·0013); 3-year recurrence-free survival was 46·5% (95% CI 41·5–51·3) in the ipilimumab group versus 34·8% (30·1–39·5) in the placebo group. The most common grade 3–4 immune-related adverse events in the ipilimumab group were gastrointestinal (75 [16%] vs four [<1%] in the placebo group), hepatic (50 [11%] vs one [<1%]), and endocrine (40 [8%] vs none). Adverse events led to discontinuation of treatment in 245 (52%) of 471 patients who started ipilimumab (182 [39%] during the initial treatment period of four doses). Five patients (1%) died due to drug-related adverse events. Five (1%) participants died because of drug-related adverse events in the ipilimumab group; three patients died because of colitis (two with gastrointestinal perforation), one patient because of myocarditis, and one patient because of multiorgan failure with Guillain-Barré syndrome. Adjuvant ipilimumab significantly improved recurrence-free survival for patients with completely resected high-risk stage III melanoma. The adverse event profile was consistent with that observed in advanced melanoma, but at higher incidences in particular for endocrinopathies. The risk–benefit ratio of adjuvant ipilimumab at this dose and schedule requires additional assessment based on distant metastasis-free survival and overall survival endpoints to define its definitive value. Bristol-Myers Squibb.

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. 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. 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]). 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. Novartis.

Ipilimumab has been shown to improve survival in patients with previously treated metastatic melanoma. In this study, ipilimumab plus dacarbazine improved survival in patients with previously untreated metastatic melanoma. The survival rate for patients with metastatic melanoma is low, with an expected 2-year survival rate of 10 to 20%. 1 – 3 Although dacarbazine has never been shown to improve survival in randomized, controlled studies, it has been the drug most frequently compared with new agents or combination therapies in randomized trials involving patients with melanoma. 4 , 5 High-dose interleukin-2 is associated with durable, complete responses, with a survival benefit, in a small subgroup of patients with metastatic melanoma. 6 , 7 Ipilimumab, a fully human, IgG1 monoclonal antibody, blocks cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4), a negative regulator of T cells, and thereby augments . . .

BRAF is a serine/threonine protein kinase activating the MAP kinase/ERK-signaling pathway. About 50 % of melanomas harbors activating BRAF mutations (over 90 % V600E). BRAFV600E has been implicated in different mechanisms underlying melanomagenesis, most of which due to the deregulated activation of the downstream MEK/ERK effectors. The first selective inhibitor of mutant BRAF, vemurafenib, after highly encouraging results of the phase I and II trial, was compared to dacarbazine in a phase III trial in treatment-naïve patients (BRIM-3). The study results showed a relative reduction of 63 % in risk of death and 74 % in risk of tumor progression. Considering all trials so far completed, median overall survival reached approximately 16 months for vemurafenib compared to less than 10 months for dacarbazine treatment. Vemurafenib has been extensively tested on melanoma patients expressing the BRAFV600E mutated form; it has been demonstrated to be also effective in inhibiting melanomas carrying the V600K mutation. In 2011, both FDA and EMA therefore approved vemurafenib for metastatic melanoma carrying BRAFV600 mutations. Some findings suggest that continuation of vemurafenib treatment is potentially beneficial after local therapy in a subset of patients with disease progression (PD). Among who continued vemurafenib >30 days after local therapy of PD lesion(s), a median overall survival was not reached, with a median follow-up of 15.5 months from initiation of BRAF inhibitor therapy. For patients who did not continue treatment, median overall survival from the time of disease progression was 1.4 months. A clinical phase I/II trial is evaluating the safety, tolerability and efficacy of vemurafenib in combination with the CTLA-4 inhibitor mAb ipilimumab. In the BRIM-7 trial vemurafenib is tested in association with GDC-0973, a potent and highly selective inhibitor of MEK1/2. Preliminary data seem to indicate that an additional inhibitor of mutated BRAF, GSK2118436, might be also active on a wider range of BRAF mutations (V600E-K-D-R); actually, treatment with such a compound is under evaluation in a phase III study among stage III-IV melanoma patients positive for BRAF mutations. Overall, BRAF inhibitors were well tolerated; common adverse events are arthralgia, rash, fatigue, alopecia, keratoacanthoma or cutaneous squamous-cell carcinoma, photosensitivity, nausea, and diarrhea, with some variants between different inhibitors.

Vismodegib, a first-in-class Hedgehog-pathway inhibitor, is approved for use in adults with advanced basal-cell carcinoma. Patients with multiple basal-cell carcinomas, including those with basal-cell nevus (Gorlin) syndrome, need extended treatment. We assessed the safety and activity of two long-term intermittent vismodegib dosing regimens in patients with multiple basal-cell carcinomas. In this randomised, regimen-controlled, double-blind, phase 2 trial, we enrolled adult patients with multiple basal-cell carcinomas, including those with basal-cell nevus syndrome, who had one or more histopathologically confirmed and at least six clinically evident basal-cell carcinomas. From a centralised randomisation schedule accessed via an interactive voice or web-based response system, patients were randomly assigned (1:1) to treatment group A (150 mg oral vismodegib per day for 12 weeks, then three rounds of 8 weeks of placebo daily followed by 12 weeks of 150 mg vismodegib daily) or treatment group B (150 mg oral vismodegib per day for 24 weeks, then three rounds of 8 weeks of placebo daily followed by 8 weeks of 150 mg vismodegib daily). Treatment assignment was stratified by diagnosis of basal-cell nevus syndrome, geographical region, and immunosuppression status. The primary endpoint was percentage reduction from baseline in the number of clinically evident basal-cell carcinomas at week 73. The primary analysis was by intention to treat. The safety population included all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, number NCT01815840, and the study is ongoing. Between April 30, 2013, and April 9, 2014, 229 patients were randomly assigned treatment, 116 in treatment group A and 113 in treatment group B. The mean number of basal-cell carcinoma lesions at week 73 was reduced from baseline by 62·7% (95% CI 53·0–72·3) in treatment group A and 54·0% (43·6–64·4) in treatment group B. 216 (95%) of 227 patients included in the safety analysis had at least one treatment-emergent adverse event deemed to be related to study treatment (107 [94%] of 114 in treatment group A and 109 [97%] of 113 in treatment group B). The most common grade 3 or worse treatment-related adverse events were muscle spasms (four [4%] patients in treatment group A vs 12 [11%] in treatment group B), increased blood creatine phosphokinase (one [1%] vs four [4%]), and hypophosphataemia (zero vs three [3%]). Serious treatment-emergent events were noted in 22 (19%) patients in treatment group A and 19 (17%) patients in treatment group B. Four (2%) patients died from adverse events; one (pulmonary embolism in treatment group A) was possibly related to treatment. Both intermittent dosing schedules of vismodegib seemed to show good activity in long-term regimens in patients with multiple basal-cell carcinomas. Further study is warranted. F Hoffmann-La Roche.

Melanoma lacks validated blood-based biomarkers for monitoring and predicting treatment efficacy. Cell-free circulating tumour DNA (ctDNA) is a promising biomarker; however, various detection methods have been used, and, to date, no large studies have examined the association between serial changes in ctDNA and survival after BRAF, MEK, or BRAF plus MEK inhibitor therapy. We aimed to evaluate whether baseline ctDNA concentrations and kinetics could predict survival outcomes. In this clinical validation study, we used analytically validated droplet digital PCR assays to measure BRAFV600-mutant ctDNA in pretreatment and on-treatment plasma samples from patients aged 18 years or older enrolled in two clinical trials. COMBI-d (NCT01584648) was a double-blind, randomised phase 3 study of dabrafenib plus trametinib versus dabrafenib plus placebo in previously untreated patients with BRAFV600 mutation-positive unresectable or metastatic melanoma. Patients had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. COMBI-MB (NCT02039947) was an open-label, non-randomised, phase 2 study evaluating dabrafenib plus trametinib in patients with BRAFV600 mutation-positive metastatic melanoma and brain metastases. Patients in cohort A of COMBI-MB had asymptomatic brain metastases, no previous local brain-directed therapy, and an ECOG performance status of 0 or 1. Biomarker analysis was a prespecified exploratory endpoint in both trials and performed in the intention-to-treat populations in COMBI-d and COMBI-MB. We investigated the association between mutant copy number (baseline or week 4 or zero conversion status) and efficacy endpoints (progression-free survival, overall survival, and best overall response). We used Cox models, Kaplan-Meier plots, and log-rank tests to explore the association of pretreatment ctDNA concentrations with progression-free survival and overall survival. The effect of additional prognostic variables such as lactate dehydrogenase was also investigated in addition to the mutant copy number. In COMBI-d, pretreatment plasma samples were available from 345 (82%) of 423 patients and on-treatment (week 4) plasma samples were available from 224 (53%) of 423 patients. In cohort A of COMBI-MB, pretreatment and on-treatment samples were available from 38 (50%) of 76 patients with intracranial and extracranial metastatic melanoma. ctDNA was detected in pretreatment samples from 320 (93%) of 345 patients (COMBI-d) and 34 (89%) of 38 patients (COMBI-MB). When assessed as a continuous variable, elevated baseline BRAFV600 mutation-positive ctDNA concentration was associated with worse overall survival outcome (hazard ratio [HR] 1·13 [95% CI 1·09–1·18], p<0·0001 by univariate analysis), independent of treatment group and baseline lactate dehydrogenase concentrations (1·08 [1·03–1·13], p=0·0020), in COMBI-d. A ctDNA cutoff point of 64 copies per mL of plasma stratified patients enrolled in COMBI-d as high risk or low risk with respect to survival outcomes (HR 1·74 [95% CI 1·37–2·21], p<0·0001 for progression-free survival; 2·23 [1·73–2·87], p<0·0001 for overall survival) and was validated in the COMBI-MB cohort (3·20 [1·39–7·34], p=0·0047 for progression-free survival; 2·94 [1·18–7·32], p=0·016 for overall survival). In COMBI-d, undetectable ctDNA at week 4 was significantly associated with extended progression-free and overall survival, particularly in patients with elevated lactate dehydrogenase concentrations (HR 1·99 [95% CI 1·08–3·64], p=0·027 for progression-free survival; 2·38 [1·24–4·54], p=0·0089 for overall survival). Pretreatment and on-treatment BRAFV600-mutant ctDNA measurements could serve as independent, predictive biomarkers of clinical outcome with targeted therapy. Novartis.