Trial results for the Phase 2 study (NCT03554083) investigating atezolizumab in combination with other agents for high-risk stage III melanoma were posted on ClinicalTrials.gov on 2026-05-04. The study explored various combinations, with the highest pathologic complete response rate (pCR) of 66.7% observed in the arm receiving vemurafenib, cobimetinib, and atezolizumab.
Background
This Phase 2 trial investigated combinations of vemurafenib, cobimetinib, atezolizumab, and tiragolumab in treating patients with high-risk stage III melanoma. The study's brief summary indicates that vemurafenib and cobimetinib may work by blocking enzymes needed for tumor cell growth, while immunotherapy with monoclonal antibodies, such as atezolizumab and tiragolumab, may help the body's immune system attack the cancer and interfere with the ability of tumor cells to grow and spread. The trial aimed to determine if these combinations could improve treatment outcomes for high-risk stage III melanoma.
Trial design
The Phase 2 study (NCT03554083) enrolled 64 participants with high-risk stage III melanoma, specifically covering Clinical Stage III Cutaneous Melanoma AJCC v8, Pathologic Stage III Cutaneous Melanoma AJCC v8, Pathologic Stage IIIA Cutaneous Melanoma AJCC v8, Pathologic Stage IIIB Cutaneous Melanoma AJCC v8, and Pathologic Stage IIIC Cutaneous Melanoma AJCC v8. The trial evaluated several treatment arms:
- Arm A: Vemurafenib, Cobimetinib, Atezolizumab
- Arm B: Cobimetinib, Atezolizumab
- Arm C: Atezolizumab, Tiragolumab
The study investigated the efficacy of these combinations in the specified patient population.
Key results
The trial reported results for several key measurements:
- Pathologic Complete Response Rate (pCR): Arm A (Vemurafenib, Cobimetinib, Atezolizumab) achieved a pCR of 66.7% of participants. Arm B (Cobimetinib, Atezolizumab) achieved 13.3%, and Arm C (Atezolizumab, Tiragolumab) achieved 38.2% of participants.
- Median Recurrence-free (RFS) Rate (Adjuvant Phase): The median RFS rate for Arm B (Cobimetinib, Atezolizumab) was 40.8 months. Median RFS rates for Arm A and Arm C were not available, and a 95% Confidence Interval for Arm B was not provided.
- Incidence of Adverse Events Per Common Terminology Criteria for Adverse Events (CTCAE): 12 participants in Arm A, 9 participants in Arm B, and 10 participants in Arm C experienced adverse events.
What this means
The results from this Phase 2 study indicate varying efficacy across the investigated combination therapies for high-risk stage III melanoma. The combination of vemurafenib, cobimetinib, and atezolizumab (Arm A) demonstrated the highest pathologic complete response rate at 66.7%, suggesting a potentially more effective regimen for achieving tumor regression compared to the other arms. While median recurrence-free survival data was limited, Arm B (cobimetinib, atezolizumab) reported a median RFS of 40.8 months. The incidence of adverse events, measured by the number of participants experiencing them, was relatively similar across all three arms, with 12, 9, and 10 participants in Arm A, Arm B, and Arm C respectively.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT03554083, titled "Vemurafenib, Cobimetinib, Atezolizumab, and Tiragolumab in Treating Patients With High-Risk Stage III Melanoma," were posted on 2026-05-04 on clinicaltrials.gov.