Cytoreductive Nephrectomy for Patients with Metastatic Sarcomatoid and/or Rhabdoid Renal Cell Carcinoma Treated with Immune Checkpoint Therapy

Background: Renal cell carcinoma (RCC) with sarcomatoid and/or rhabdoid (S/R) dedifferentiation is a highly aggressive tumor with a poor prognosis. Immune checkpoint therapy (ICT) has shown significant treatment efficacy in this subtype. There remains uncertainly regarding the role of cytoreductive nephrectomy (CN) for patients with metastatic RCC (mRCC) with S/R who received ICT. Objective: Here, we report the outcomes with ICT for patients with mRCC and S/R dedifferentiation by CN status. Design, setting, and participants: A retrospective review was conducted of 157 patients with sarcomatoid, rhabdoid, or sarcomatoid plus rhabdoid dedifferentiation who received an ICT-based regimen at two cancer centers. Intervention: CN performed at any time point; nephrectomy with curative intent was excluded. Outcome measurements and statistical analysis: ICT treatment duration (TD) and overall survival (OS) from ICT initiation were recorded. To address the immortal time bias, a time-dependent Cox regression model was generated that accounted for confounders identified by a directed acyclic graph as well as a time-dependent nephrectomy variable. Results and limitations: A total of 118 patients underwent CN, and of them, 89 underwent upfront CN. The results did not contradict the supposition that CN does not improve ICT TD (hazard ratio [HR] 0.98, 95% confidence interval [CI] 0.65–1.47, p = 0.94) or OS from ICT initiation (HR 0.79, 95% CI 0.47–1.33, p = 0.37). In patients who underwent upfront CN compared with those who did not undergo CN, there was no association with ICT duration or OS (HR 0.61, 95% CI 0.35–1.06, p = 0.08). A detailed clinical summary of 49 patients with mRCC and rhabdoid dedifferentiation is provided. Conclusions: In this multi-institutional cohort of mRCC with S/R dedifferentiation treated with ICT, CN was not significantly associated with improved TD or superior OS when accounting for the lead time bias. There appears to be a subset of patients who derive meaningful benefit from CN, so improved tools for stratification prior to CN are needed to optimize outcomes. Patient summary: Immunotherapy has improved outcomes for patients with metastatic renal cell carcinoma (mRCC) who have sarcomatoid and/or rhabdoid (S/R) dedifferentiation, which is an aggressive and uncommon feature; yet, the utility of a nephrectomy in this setting is unclear. We found that nephrectomy did not significantly improve survival or time on immunotherapy for these patients with mRCC and S/R dedifferentiation; yet, there may be a subset of patients who benefit from this surgical approach.