SUMMARY: The American Cancer Society estimates that for 2022, about 99,780 new cases of melanoma of the skin will be diagnosed in the United States and 7,650 people are expected to die of the disease. The rates of melanoma have been rising rapidly over the past few decades, but this has varied by age.
The Mitogen-Activated Protein Kinase pathway (MAPK pathway) is an important signaling pathway which enables the cell to respond to external stimuli. This pathway plays a dual role, regulating cytokine production and participating in cytokine dependent signaling cascade. The MAPK pathway of interest is the RAS-RAF-MEK-ERK pathway. The RAF family of kinases includes ARAF, BRAF and CRAF signaling molecules. BRAF is a very important intermediary of the RAS-RAF-MEK-ERK pathway. BRAF mutations have been detected in 6-8% of all malignancies. The most common BRAF mutation in melanoma is at the V600E/K site and is detected in approximately 50% of melanomas, and results in constitutive activation of the MAPK pathway.
Immunotherapy with Immune Checkpoint Inhibitors (ICIs) has revolutionized cancer care and has become one of the most effective treatment options by improving Overall Response Rate (ORR) and prolongation of survival across multiple tumor types. These agents target Programmed cell Death protein-1 (PD-1), Programmed cell Death Ligand-1 (PD-L1), Cytotoxic T-Lymphocyte-Associated protein-4 (CTLA-4), and many other important regulators of the immune system. Over 50% of patients treated with a combination of PD-1 and CTLA-4 inhibitors are alive after five years.
TAFINLAR® (Dabrafenib), is a selective oral BRAF inhibitor and MEKINIST® (Trametinib) is a potent and selective inhibitor of MEK gene, which is downstream from RAF in the MAPK pathway. TAFINLAR® plus MEKINIST® led to long-term survival benefit in approximately one third of the patients who had unresectable or metastatic melanoma with a BRAF V600E or V600K mutation, from two randomized Phase III COMBI-d and COMBI-v trials.
A combination of OPDIVO® (Nivolumab) plus YERVOY® (Ipilimumab) showed durable improved outcomes among patients with unresectable or metastatic melanoma and approximately 50% of patients were alive at 6.5 years (J Clin Oncol 39, 2021. suppl 15; abstr 9506). The FDA granted approval for this combination in 2015 for the treatment of patients with metastatic melanoma, regardless of tumor BRAF mutation status.
It has been noted that BRAF/MEK inhibitor therapy tends to produce high tumor response rates and prolonged median Progression Free Survival (PFS), whereas OPDIVO® /YERVOY® tends to have its major impact on Duration of Response. However, the optimal treatment sequence for patients with treatment-naive BRAFV600-mutant metastatic melanoma, between combination OPDIVO®/YERVOY® checkpoint inhibitor immunotherapy and combination TAFINLAR® plus MEKINIST® molecularly targeted therapy, has remained unclear. Recently published tumor biology studies have suggested that resistance to BRAF/MEK-inhibitor therapy results in an immunosuppressive tumor microenvironment that is void of functional CD103+ dendritic cells, preventing effective antigen presentation to the immune system, and that immunotherapy may enhance BRAF-mutated melanoma responsiveness to targeted therapy.
DREAMseq (EA6134) is a two-arm, two-step, open-label, randomized Phase III trial, which investigated the anti PD-1/CLTA-4 immunotherapy combination of OPDIVO® plus YERVOY® followed by the anti-BRAF/MEK targeted therapy combination of TAFINLAR® plus MEKINIST®, versus the reverse sequence, in patients with advanced BRAF V600-mutant melanoma. This study was conducted to determine which treatment sequence produced the best efficacy.
In this study, 265 patients with treatment-naive BRAF V600-mutant metastatic melanoma were randomly assigned to receive either combination OPDIVO® plus YERVOY® (arm A=133) or TAFINLAR® plus MEKINIST® (arm B=132) in step 1, and at disease progression were enrolled in step 2 to receive the alternate therapy, TAFINLAR® plus MEKINIST® (arm C=27) or OPDIVO® plus YERVOY® (arm D=46). The two initial treatment arms were balanced and more patients on arm B had BRAF V600K-mutant tumors than those on arm A (25.2% versus 12.1%). The median patient age was 61 years and eligible patients had histologically confirmed, BRAF V600-mutant unresectable Stage III or IV melanoma with measurable disease. The Primary end point was 2-year Overall Survival (OS). Secondary end points included 3-year OS, Objective Response Rate (ORR), Duration of Response, Progression Free Survival (PFS), crossover feasibility, and Safety.
The study was stopped early by the Independent Data Safety Monitoring Committee because statistical significance was achieved for the Primary endpoint. The 2-year OS for those starting on arm A was 71.8% and arm B was 51.5% (P=0.01). Step 1 Progression Free Survival favored arm A (P=0.054). The Objective Response Rates were arm A: 46%, arm B: 43%, arm C: 47.8%, and arm D: 29.6%. The median Duration of Response was not reached for arm A, and 12.7 months for arm B (P<0.001). Crossover occurred in 52% of patients following documented disease progression. Grade 3 or more toxicities occurred with similar frequency between treatment groups and adverse events related to regimens were as expected.
It was concluded from this study that for patients with advanced BRAF V600-mutant metastatic melanoma, the treatment sequence beginning with the immune checkpoint inhibitor combination of OPDIVO® plus YERVOY® resulted in superior Overall Survival and longer Duration of Response, compared with the treatment sequence beginning with TAFINLAR® plus MEKINIST®, and should therefore be the preferred treatment sequence for most of these patients.
Combination Dabrafenib and Trametinib Versus Combination Nivolumab and Ipilimumab for Patients with Advanced BRAF-Mutant Melanoma: The DREAMseq Trial—ECOG-ACRIN EA6134. Atkins MB, Lee SJ, Chmielowski B, et al. J Clin Oncol. Published online September 27, 2022. doi:10.1200/JCO.22.01763