Modest efficacy of nivolumab plus ipilimumab in patients with papillary renal cell carcinoma

Purpose Combined immunotherapy of nivolumab plus ipilimumab for intermediate- and poor-risk metastatic clear cell renal cell carcinoma showed prolonged progression-free survival and high objective response rate in a randomized phase III clinical trial. However, the efficacy of this treatment for papillary renal cell carcinoma remains unclear. In the present study, we analysed the efficacy of nivolumab plus ipilimumab therapy for papillary renal cell carcinoma compared with that for clear cell renal cell carcinoma. Materials and Methods This is a retrospective study of 30 patients with metastatic renal cell carcinoma who received nivolumab and ipilimumab as first-line therapy between December 2015 and May 2020. The objective response rate, progression-free survival and toxicity were compared between the two groups (clear cell renal cell carcinoma and papillary renal cell carcinoma). Results Out of 30 patients, 7 and 23 were diagnosed with papillary renal cell carcinoma and clear cell renal cell carcinoma, respectively. With a median follow-up of 7.2 months, the median progression-free survival was significantly shorter in papillary renal cell carcinoma than in clear cell renal cell carcinoma (2.4 vs. 28.1 months, P = 0.014). Of the seven patients with papillary renal cell carcinoma, one had partial response, one had stable disease and five had progressive disease, resulting in an objective response rate of 14.2%, which was lower compared to that of clear cell renal cell carcinoma (14.2 vs. 52.1%, P = 0.06). Discontinuation due to toxicity was not observed with papillary renal cell carcinoma, meanwhile 60.8% of patient with clear cell renal cell carcinoma discontinued treatment due to toxicity. Conclusion Nivolumab plus ipilimumab had modest efficacy for papillary renal cell carcinoma compared with that for clear cell renal cell carcinoma. Nivolumab plus ipilimumab remains an option for a limited number of patients with intermediate- or poor-risk papillary renal cell carcinoma.