Radiomic biomarkers associated with immune checkpoint blockade response for advanced renal cell carcinoma.

[PURPOSE] Immune checkpoint blockade (ICB) has transformed outcomes for patients with metastatic renal cell carcinoma (mRCC) and has impacted the timing and use of cytoreductive nephrectomy (CN). As ICB responses vary, we evaluated whether radiographic and radiomic biomarkers were associated with clinical and pathological outcomes.

[METHODS] This retrospective cohort study included ICB-treated mRCC patients without upfront CN. Clinical and treatment data were collected, and time to next therapy (TTNT) and overall survival (OS) were estimated using Kaplan-Meier analysis. Univariable regression analyses were performed to correlate extracted radiomic features with pathologic outcomes from patients who underwent delayed CN.

[RESULTS] From 2015 to 2022, 60 mRCC patients met inclusion criteria. Among 43 patients with available imaging data, patients with 3-month radiologic response at both primary and metastatic sites had significantly prolonged TTNT and OS compared to those with progressive disease (PD) at both sites (6-month TTNT 95% vs. 0% and 12-month OS 100% vs. 20%). Primary tumor imaging overestimated pathologically confirmed viable tumor by an average of 622 cm (95% CI 285-958 cm). Imaging contrast enhancement and change in enhancement correlated with pathologic viability (Spearman ρ=0.41 and 0.39, respectively). Radiomic features of energy, run length nonuniformity, busyness, and gray-level nonuniformity identified patients with minimal residual disease with area under the curve (AUC) >0.84.

[CONCLUSION] Response patterns in primary and metastatic tumor sites are associated with ICB outcomes. Radiomic features extracted from raw imaging provide an improved surrogate for estimating tumor viability. Efforts to optimize and integrate radiomic data for treatment decision-making are needed.