Pretreatment and on-treatment ctDNA and tissue biomarkers predict recurrence in patients with stage IIIB-D/IV melanoma treated with adjuvant immunotherapy: CheckMate 915.

Purpose: CheckMate 915 (NCT03068455) compared adjuvant nivolumab monotherapy versus combination nivolumab+ipilimumab in patients with resected stage III/IV melanoma. This exploratory analysis was performed to identify biomarkers that correlate with benefit from adjuvant immunotherapy.

Patients And Methods: 1,844 patients received nivolumab 480 mg every 4 weeks or nivolumab 240 mg every 2 weeks with ipilimumab 1 mg/kg every 6 weeks. Tumor and peripheral biomarkers were evaluated, including tumor-informed circulating tumor DNA (ctDNA) at postresection baseline and on-treatment, for their association with recurrence-free survival and distant metastases-free survival.

Results: Biomarker analyses were conducted in 60-96% of the intention-to-treat population. ctDNA positivity at baseline (seen in 16.2% of patients) and on-treatment was associated with higher risk of recurrence than ctDNA negativity (HR, 1.97; 95% CI, 1.57 to 2.46), with a high specificity (87%) and modest sensitivity (39%). ctDNA status, tumor mutational burden (TMB) status (TMB < or ≥350 mutations/tumor) and interferon gamma-RNA signature score (< or ≥median) evaluated together, as well as ctDNA status with tumor CD8 or cell programmed death ligand 1 expression, were more predictive of survival than ctDNA alone. Tumor bulk RNA-seq expression patterns identified gene expression at baseline associated with recurrence.

Conclusions: This study represents the largest assessment of ctDNA and other baseline tumor and peripheral biomarkers for predicting recurrence-free survival in patients with resected melanoma receiving adjuvant immunotherapy. ctDNA alone and in combination with more established biomarkers predicted recurrence-free and distant metastasis-free survival and has potential utility for assessing and monitoring the risk of recurrence in patients with resected melanoma treated with immunotherapy in the adjuvant setting.

Trial Registration Number: NCT03068455.