An ultra-sensitive circulating tumor DNA (ctDNA) assay can accurately distinguish between partial and complete responses to immunotherapy for metastatic renal cell carcinoma (mRCC), investigators reported at IKCS: Europe 2022.

This assay could be used in studies to identify appropriate candidates for immune checkpoint inhibitor (ICI) therapy, according to Alexander Chehrazi-Raffle, MD, of City of Hope Comprehensive Cancer Center in Duarte, California, and colleagues.

The investigators evaluated the TARDIS (TARgeted Digital Sequencing) assay on 12 patients treated with either nivolumab monotherapy or nivolumab plus ipilimumab. They analyzed 36 somatic variants per patient. Of the 12 patients, 8 had clear cell and 4 had variant histology; 9 had a partial response and 3 had a complete response.

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The ctDNA analysis incorporated an average of 30 patient-specific mutations, with an average coverage depth of 103,342 read families per sample.

TARDIS quantified a significant difference in variant allele fractions between partial and complete response. In addition, 6 patients had radiographic progression subsequent to ctDNA assessment. TARDIS demonstrated a significant difference in variant allele fractions between patients who had sustained radiographic response and those who progressed on subsequent imaging, the authors reported.


Chehrazi-Raffle A, Muddasani R, Disman N, et al. Ultra-sensitive circulating tumor DNA (ctDNA) assay distinguishes partial response (PR) and complete response (CR) with immunotherapy in metastatic renal cell carcinoma (mRCC). Presented at: IKCS Europe 2022, April 22-24, 2022, Antwerp, Belgium. Poster 25.