Three-year pooled analysis of factors associated with clinical outcomes across dabrafenib and trametinib combination therapy phase 3 randomised trials.

AIM: Understanding predictors of long-term benefit with currently available melanoma therapies is the key for optimising individualised treatments. A prior pooled analysis of dabrafenib plus trametinib (D + T)-randomised trials (median follow-up, 20.0 months) identified baseline lactate dehydrogenase (LDH) and number of organ sites with metastasis as predictive factors for progression-free (PFS) and overall (OS) survival. However, longer-term follow-up analyses are needed to confirm which patients treated with D + T can achieve maximum benefit. METHODS: Three-year landmark data were retrospectively pooled for D + T patients in phase 3 trials (COMBI-d [NCT01584648]; COMBI-v [NCT01597908]). Univariate and multivariate analyses assessed prognostic values of predefined baseline factors; regression tree analysis determined hierarchy and interactions between variables. RESULTS: Long-term pooled outcomes were consistent with individual trial results (N = 563; 3-year PFS, 23%; 3-year OS, 44%). Baseline LDH level and number of organ sites remained strongly associated with and/or predictive of PFS and OS. In addition, baseline sum of lesion diameters (SLD) was identified as a predictor for progression. In the most favourable prognostic group (normal LDH, SLD <66 mm, <3 organ sites; n = 183/563 [33%]), 3-year PFS was 42%. Baseline number of organ sites was also predictive of outcomes in patients with PFS ≥ 6 months. CONCLUSION: Using the largest phase 3 data set available for BRAF/MEK inhibitor combination therapy in melanoma, these results demonstrate that durable responses lasting ≥3 years are possible in subsets of patients with BRAF-mutant melanoma receiving D + T. Although the best predictive model evolved with longer follow-up, factors predicting clinical outcomes with the combination remained consistent with previous analyses.

Improved overall survival in melanoma with combined dabrafenib and trametinib.

BACKGROUND: The BRAF inhibitors vemurafenib and dabrafenib have shown efficacy as monotherapies in patients with previously untreated metastatic melanoma with BRAF V600E or V600K mutations. Combining dabrafenib and the MEK inhibitor trametinib, as compared with dabrafenib alone, enhanced antitumor activity in this population of patients. METHODS: In this open-label, phase 3 trial, we randomly assigned 704 patients with metastatic melanoma with a BRAF V600 mutation to receive either a combination of dabrafenib (150 mg twice daily) and trametinib (2 mg once daily) or vemurafenib (960 mg twice daily) orally as first-line therapy. The primary end point was overall survival. RESULTS: At the preplanned interim overall survival analysis, which was performed after 77% of the total number of expected events occurred, the overall survival rate at 12 months was 72% (95% confidence interval [CI], 67 to 77) in the combination-therapy group and 65% (95% CI, 59 to 70) in the vemurafenib group (hazard ratio for death in the combination-therapy group, 0.69; 95% CI, 0.53 to 0.89; P=0.005). The prespecified interim stopping boundary was crossed, and the study was stopped for efficacy in July 2014. Median progression-free survival was 11.4 months in the combination-therapy group and 7.3 months in the vemurafenib group (hazard ratio, 0.56; 95% CI, 0.46 to 0.69; P<0.001). The objective response rate was 64% in the combination-therapy group and 51% in the vemurafenib group (P<0.001). Rates of severe adverse events and study-drug discontinuations were similar in the two groups. Cutaneous squamous-cell carcinoma and keratoacanthoma occurred in 1% of patients in the combination-therapy group and 18% of those in the vemurafenib group. CONCLUSIONS: Dabrafenib plus trametinib, as compared with vemurafenib monotherapy, significantly improved overall survival in previously untreated patients with metastatic melanoma with BRAF V600E or V600K mutations, without increased overall toxicity. (Funded by GlaxoSmithKline; ClinicalTrials.gov number, NCT01597908.).