Long-term data from the phase 2 ImmunoCobiVem trial indicates a potential survival benefit for patients with BRAF V600–positive melanoma who switch to atezolizumab (Tecentriq) after an initial run-in treatment with vemurafenib (Zelboraf) plus cobimetinib (Cotellic). The findings, presented at the 2024 European Society for Medical Oncology (ESMO) Congress, suggest a trend toward improved overall survival, although the improvement was not statistically significant.
The ImmunoCobiVem trial enrolled patients with previously untreated unresectable or metastatic BRAF V600–mutated melanoma. Following a 3-month run-in phase with vemurafenib and cobimetinib, patients without progressive disease were randomized to either continue the targeted therapy combination (Arm A, n = 69) or switch to atezolizumab monotherapy (Arm B, n = 66) until disease progression.
At a median follow-up of 57 months, the median overall survival (OS) was 40.2 months (95% CI, 18.9-NE) in Arm A versus 49.6 months (95% CI, 26.1-NE) in Arm B (HR, 1.17; 95% CI, 0.71-1.91; stratified P = .94). The 60-month OS rates were 40% and 45%, respectively.
Progression-Free Survival
Initial progression-free survival (PFS1) favored continuous targeted therapy. Patients in Arm A (n = 68) experienced a median PFS1 of 13.0 months (95% CI, 9.9-15.6) compared to 5.9 months (95% CI, 5.5-8.3) in Arm B (n = 65; HR, 0.61; 95% CI, 0.41-0.91; stratified P = .006). The 60-month PFS1 rates were 19% and 15%, respectively.
Crossover Analysis
An analysis of patients who crossed over to the alternative treatment upon disease progression revealed interesting trends. The time to second progression (PFS3) was 2.8 months (95% CI, 2.1-3.3) among those in Arm A who received vemurafenib plus cobimetinib and then atezolizumab (n = 21), compared with 6.0 months (95% CI, 2.1-8.8) among those in Arm B who received atezolizumab then vemurafenib plus cobimetinib (n = 35; HR, 1.72; 95% CI, 0.93-3.20). The 48-month PFS3 rates were 10% and 17%, respectively. The total PFS (PFS2) was 12.6 months (95% CI, 8.3-17.0) in Arm A versus 14.6 months (95% CI, 8.6-25.6) in Arm B (HR, 1.29; 95% CI, 0.70-2.38; P = .41); 60-month PFS2 rates were 10% and 21%, respectively.
Dirk Schadendorf, MD, of the University of Essen and the German Cancer Consortium, noted that "a relevant number of patients experienced rapid progression after early switch from targeted therapy to immune checkpoint inhibition." He also stated that "no subgroups were identified for which a targeted therapy run in provided clinical benefit."
Trial Design
The ImmunoCobiVem trial randomized patients 1:1 to the two treatment arms, stratifying by serum lactate dehydrogenase (LDH) levels, metastatic stage of disease, and prior adjuvant therapy. All patients received vemurafenib (960 mg twice daily) and cobimetinib (60 mg once daily) during the 3-month run-in phase. Following randomization, patients in Arm A continued the combination therapy, while those in Arm B switched to atezolizumab (1200 mg every 3 weeks). Crossover to the opposite arm's regimen was permitted upon disease progression.
