Role of enhancement modifications in evaluating tumor response to immunotherapy in metastatic renal cell carcinoma

Introduction: Evaluation of tumor response according only to dimensional criteria may underestimate treatment benefit in patients treated for metastatic renal cell carcinoma (RCC). In this study we evaluated the role of lesion enhancement modifications and Choi criteria in patients affected by renal cell carcinoma treated with immunotherapy. Methods: We collected data of 60 consecutive patients (with a total of 154 measurable lesions) treated with immunotherapy (nivolumab or ipilimumab plus nivolumab) at a single Institution. We evaluated tumour response using both RECIST1.1 criteria and Choi criteria at the first radiological assessment; we subsequently associated response with progression free survival and overall survival. Results: Choi criteria found a higher rate of objective response compared to RECIST criteria (38.3% vs 18.3%). An objective response according to both criteria was associated with longer progression free survival and overall survival. Response rate for Choi did not vary according to lesion site. Conclusion: Choi criteria seemed to be able to predict clinical benefit in a higher proportion of patients with renal cell carcinoma treated with immunotherapy than RECIST criteria. Partial response according to RECIST was confirmed as a predictor of longer progression-free survival and overall survival.