A final analysis of the Phase III COMBI-AD trial indicates that adjuvant therapy with Tafinlar (dabrafenib) plus Mekinist (trametinib) significantly improves outcomes for patients with resected stage III melanoma. The study, published in The New England Journal of Medicine, followed patients for over eight years, revealing improved relapse-free survival (RFS) and distant metastasis–free survival (DMFS) compared to placebo.
Survival Benefits
While the overall survival (OS) benefit did not reach statistical significance (hazard ratio for death, 0.80; 95% CI, 0.62 to 1.01; P=0.06), the combination therapy reduced the risk of death by 20%. Notably, in patients with the BRAF V600E mutation, the risk of death was reduced by 25%.
"The analysis of [OS] showed that the risk of death was 20% lower with [Tafinlar plus Mekinist] than with placebo, but the benefit was not significant," the study authors wrote.
Mechanism of Action
Tafinlar and Mekinist target different growth-promoting signals within tumor cells activated by the BRAF V600E mutation. Tafinlar inhibits signaling from the BRAF protein, while Mekinist blocks signals from the MEK protein. This combination approach is designed to prevent tumors from developing resistance mechanisms.
Trial Design and Results
The COMBI-AD trial randomized 870 patients with resected stage III melanoma and BRAF V600 mutations to either Tafinlar (150 mg twice daily) plus Mekinist (2 mg once daily) or placebo for 12 months. The median duration of follow-up was 8.33 years for the combination therapy group and 6.87 years for the placebo group.
In addition to the observed trend in overall survival, the combination therapy demonstrated a significant improvement in RFS (hazard ratio for relapse or death, 0.52; 95% CI, 0.43 to 0.63) and DMFS (hazard ratio for distant metastasis or death, 0.56; 95% CI, 0.44 to 0.71).
Safety Profile
The safety profile of Tafinlar and Mekinist remained consistent with previous clinical trials, with no new safety signals reported during the extended follow-up period.
Current Indications
The Tafinlar and Mekinist combination is currently approved for various indications, including unresectable or metastatic melanoma with BRAF V600E or V600K mutations, adjuvant treatment of melanoma with BRAF V600E or V600K mutations and lymph node involvement, metastatic non-small cell lung cancer with BRAF V600E mutation, and other solid tumors with BRAF V600E mutation under specific conditions.
