Circulating tumor DNA is making the rounds as the most sensitive early detection for residual or recurrent malignancy. Here is a small but promising feasibility study which assessed ctDNA following firstline immune checkpoint inhibition for metastatic renal cell carcinoma. Among 12 patients, 9 had a synchronous partial response on imaging and 3 had a complete response. Variant allele frequencies were orders of magnitude greater among those with a partial (median 0.181%, IQR 0.077-0.420) versus complete (0.007%, IQR 0.0-0.028) response. Perhaps even more interesting was the discrepancy between the half that went on to have radiographic progression (median 0.362%, IQR 0.181-2.71) versus the half that didn’t (0.033%, IQR 0.007-0.077). | Chehrazi-Raffle, J Clin Oncol 2023
