LAUSR

INTRODUCTION Metastases from renal cell carcinoma develop in various organs. However, the breadth of discrepancy in response to immune checkpoint inhibitors across tumor sites within the same individual remains unclear. PATIENTS AND METHODS We reviewed 50 patients with metastatic renal cell carcinoma who had target lesions at multiple sites and received nivolumab monotherapy (n = 36) or nivolumab plus ipilimumab (n = 14). When the best overall response in tumor burden increased at one site but decreased at other sites, the response was defined as a dissociated response. The response was evaluated according to the Response Evaluation Criteria in Solid Tumors 1.1, and patients who met the definition of dissociated response were categorized as dissociated response. The rate of dissociated response and prognosis were evaluated. RESULTS Eight of 36 (22%) and 4 of 14 (29%) patients treated with nivolumab and nivolumab plus ipilimumab were categorized as having dissociated response, respectively. The median overall survival of the patients treated with nivolumab was 20.2 months for those with a partial response, 6.8 months for those with stable disease, and 13.2 months for those with progressive disease, while dissociated response was not reached. There was no significant difference in the median overall survival between patients categorized as having progressive disease and those with dissociates response (P = 0.224). CONCLUSION A certain proportion of patients with metastatic renal cell carcinoma show dissociated response when treated with immune checkpoint inhibitors. The prognosis of patients with dissociated response and progressive disease was not shown to be significantly different.