Real-world efficacy and safety of nivolumab plus ipilimumab in untreated metastatic renal cell carcinoma, and the impact of previous nephrectomy on clinical outcome: Japanese multi-institutional retrospective study

Background In metastatic renal-cell carcinoma (mRCC), recent clinical trials have shown efficacy of first-line combination therapy, as evidenced by better clinical outcome over target therapy. However, there are insufficient real-world evidences in mRCC patients in Japan. Methods We performed a multicenter retrospective study of 72 mRCC patients who received nivolumab plus ipilimumab as first-line treatment between September 2018 and July 2021. Patient's characteristics, clinical outcomes and safety were retrospectively reviewed. We analyzed overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) in patients treated with combination therapy. Results Of all patients, the median age was 70 years (range, 36-86) and the major type of histology was clear cell RCC (n = 55; 76.4%). Progressive disease (n = 25; 34.8%) and irAEs (n = 22; 30.6%) were the most common causes for discontinuing treatment. Median PFS and OS seemed similar between patients who discontinued treatment because of irAEs and for patients who did not (p = 0.360 and p = 0.069, respectively). Importantly, for patients with synchronous metastatic disease at diagnosis (n = 56), nephrectomy before initiating nivolumab plus ipilimumab had a significantly positive impact on better OS when compared to that in patients without nephrectomy (p = 0.028). Conclusion This study confirms efficacy and safety of nivolumab plus ipilimumab for mRCC patients in real-world settings. Furthermore, nivolumab plus ipilimumab was associated with a better outcome in patients who had undergone nephrectomy at diagnosis for synchronous mRCC.