Abstract CT012: Evaluation of atezolizumab (A), cobimetinib (C), and vemurafenib (V) in previously untreated patients with BRAFV600 mutation-positive advanced melanoma: Primary results from the phase 3 IMspire150 trial
Authors: McArthur Grant A. , Stroyakovskiy Daniil , Gogas Helen , Robert Caroline , Lewis Karl , Protsenko Svetlana , Pereira Rodrigo , Eigentler Thomas , Rutkowski Piotr , Demidov Lev , Manikhas Georgy Moiseevich , Yan Yibing , Huang K. C. , Uyei Anne , McNally Virgina , Gutzmer Ralf , Ascierto Paolo 
Published: September 2020

Background: Approved systemic treatments for advanced melanoma include immune checkpoint inhibitor therapy (CIT) and targeted therapy with BRAF plus MEK inhibitors for BRAFV600E/K mutant melanoma. Response rates with CITs are typically lower than those observed with targeted therapy, but CIT responses are more durable. Preclinical and clinical data suggest a potential for synergy between CIT and BRAF plus MEK inhibitors. We therefore evaluated whether combining CIT with targeted therapy could improve efficacy vs targeted therapy alone. Methods: Treatment-naive patients with unresectable stage IIIc/IV melanoma (AJCC 7th ed), measurable disease by RECIST 1.1, and BRAFV600 mutations in their tumors were randomized to the anti-programmed death-ligand 1 antibody A + C + V or placebo (Pbo) + C + V. A or Pbo were given on days 1 and 15 of each 28-day cycle. Treatment was continued until disease progression or unacceptable toxicity. The primary outcome was investigator-assessed progression-free survival (PFS). Results: 514 patients were enrolled (A + C + V = 256; Pbo + C + V = 258) and followed for a median of 18.9 months. Investigator-assessed PFS was significantly prolonged with A + C + V vs Pbo + C + V (15.1 vs 10.6 months, respectively; hazard ratio: 0.78; 95% confidence interval: 0.63-0.97; P=0.025), an effect seen in all prognostic subgroups. While objective response rates were similar in the A + C + V and Pbo + C + V groups, median duration of response was prolonged with A + C + V (21.0 months) vs Pbo + C + V (12.6 months). Overall survival data were not mature at the time of analysis. Common treatment-related adverse events (AEs; &gt;30%) in the A + C + V and Pbo + C + V groups were blood creatinine phosphokinase (CPK) increase (51.3% vs 44.8%), diarrhea (42.2% vs 46.6%), rash (40.9% in both arms), arthralgia (39.1% vs 28.1%), pyrexia (38.7% vs 26.0%), alanine aminotransferase (ALT) increase (33.9% vs 22.8%), and lipase increase (32.2% vs 27.4%). Common treatment-related grade 3/4 AEs (&gt;10%) that occurred in the A + C + V and Pbo + C + V groups were lipase increase (20.4% vs 20.6%), blood CPK increase (20.0% vs 14.9%), ALT increase (13.0% vs 8.9%), and maculopapular rash (12.6% vs 9.6%). The incidence of treatment-related serious AEs was similar between the A + C + V (33.5%) and Pbo + C + V (28.8%) groups. 12.6% of patients in the A + C + V group and 15.7% in the Pbo + C + V group stopped all treatment because of AEs. The safety profile of the A + C + V regimen was generally consistent with the known profiles of the individual components. Conclusion: Combination therapy with A + C + V was tolerable and manageable, produced durable responses, and significantly increased PFS vs Pbo + C + V. Thus, A + C + V represents a viable treatment option for BRAFV600 mutation-positive advanced melanoma. ClinicalTrials.gov ID: NCT02908672

Citation Format: Grant A. McArthur, Daniil Stroyakovskiy, Helen Gogas, Caroline Robert, Karl Lewis, Svetlana Protsenko, Rodrigo Pereira, Thomas Eigentler, Piotr Rutkowski, Lev Demidov, Georgy Moiseevich Manikhas, Yibing Yan, K. C. Huang, Anne Uyei, Virgina McNally, Ralf Gutzmer, Paolo Ascierto. Evaluation of atezolizumab (A), cobimetinib (C), and vemurafenib (V) in previously untreated patients with BRAFV600 mutation-positive advanced melanoma: Primary results from the phase 3 IMspire150 trial [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT012.