Early switch from run-in with targeted to immunotherapy in advanced BRAFV600-positive melanoma: final results of the randomised phase II ImmunoCobiVem trial.

BACKGROUND

Optimal sequencing of immune checkpoint inhibitors (ICIs) and targeted therapies (TTs) in BRAFV600-positive advanced melanoma should achieve rapid tumour control and durable progression-free survival (PFS), translating into prolonged overall survival (OS).

PATIENTS AND

METHODS

The 1 : 1 randomised phase II ImmunoCobiVem trial compared-after a 3-month run-in phase with vemurafenib (VEM, 960 mg twice daily) and cobimetinib (COB, 60 mg daily days 21-28, q4w)-continuous VEM + COB until disease progression (PD1) and second-line atezolizumab (ATEZO, 1200 mg, q3w) in arm A versus early switch to ATEZO after run-in, followed by crossover to VEM + COB at PD1, in arm B. PFS from the start of run-in until PD1 was the primary endpoint (PFS1); secondary efficacy endpoints were OS, overall PFS (PFS2) and PFS3 (time from PD1 to PD after crossover, i.e. PD2) and best overall response rates (BORRs).

RESULTS

The final analysis (median follow-up 57.0 months, interquartile range 22.7-63.0 months) confirmed longer PFS1 for continuous TT [arm A (69 patients) versus arm B (early switch, 66 patients); hazard ratio (HR) 0.61, 95% confidence interval (CI) 0.41-0.91, P = 0.006], but early switch to ICIs resulted in better long-term OS [4- and 5-year landmark OS 42% (95% CI 29% to 55%) and 40% (95% CI 27% to 53%) for arm A, and 53% (95% CI 38% to 65%) and 45% (95% CI 31% to 58%) for arm B; descriptive HR 1.17, 95% CI 0.71-1.91]. Absolute BORRs were 81% and 89%, respectively, with 15 (22%) and 19 (29%) patients achieving a complete response at least once along each sequence. At crossover, TT retreatment (arm B) resulted in higher PFS3 than second-line ICI (arm A).

CONCLUSIONS

Early switch to ICIs after TT run-in (arm B) led to an improved, although not statistically significant, 4- and 5-year landmark OS compared with arm A. No subgroups were identified for which a TT run-in provided clinical benefit. The number of patients developing brain metastasis and the time to brain metastasis were not improved by an early TT to ICI switch.