Significance of upfront cytoreductive nephrectomy stratified by IMDC risk for metastatic renal cell carcinoma in targeted therapy era – a multi-institutional retrospective study

Background This retrospective multicenter study aimed to evaluate the survival benefit of upfront cytoreductive nephrectomy (CN) in metastatic renal cell carcinoma (RCC) patients stratified by International Metastatic RCC Database Consortium (IMDC) risk criteria. Methods We reviewed the medical records in the Michinoku Database between 2008 and 2019. Patients who received upfront CN, systemic therapy without CN (no CN) and CN after drug therapy (deferred CN) were analyzed. To exclude selection bias due to patient characteristics, baseline clinical data were adjusted by inverse probability of treatment weighting (IPTW). Overall survival (OS) was compared between upfront CN and non-upfront CN (no CN plus deferred CN). Associations between time-varying covariates including systemic therapies and OS stratified by IMDC risk criteria were analyzed by IPTW-adjusted Cox regression method. Results Of 259 patients who fulfilled the selection criteria, 107 were classified in upfront CN and 152 in non-upfront CN group. After IPTW-adjusted analysis, upfront CN showed survival benefit compared to non-upfront CN in patients with IMDC intermediate risk (median OS: 52.5 versus 31.3 months, p < 0.01) and in patients with IMDC poor risk (27.2 versus 11.4 months, p < 0.01). In IPTW-adjusted Cox regression analysis of time-varying covariates, upfront CN was independently associated with OS benefit in patients with IMDC intermediate risk (hazard ratio 0.52, 95% confidence interval 0.29–0.93, p = 0.03) and in patients with IMDC poor risk (0.26, 0.11–0.59, p < 0.01). Conclusions Upfront CN may confer survival benefit in RCC patients with IMDC intermediate and poor risk.

“PROBE”ing the Role of Cytoreductive Nephrectomy in Advanced Renal Cancer

The Southwest Oncology Group (SWOG)1931 trial, also known as PROBE (ClinicalTrials.gov Identifier: NCT04510597) is a phase III study evaluating the role of cytoreductive nephrectomy (CN) in metastatic renal cell cancer (RCC). Kidney cancer presenting with synchronous metastases has demonstrated shorter survival outcome compared to the patients relapsing with metastases after nephrectomy. Previously, CN has been associated with survival improvement when interferon-based systemic therapy was used. In the setting of antivascular therapy sunitinib, a prospective randomized clinical trial demonstrated no benefit of CN. Immune checkpoint-based combination therapy has now become the standard-of-care in the frontline setting for RCC. The role of nephrectomy or primary resection has not been evaluated in the setting of immune checkpoint-based systemic therapy. The sequence and optimal timing of nephrectomy is also not established. The PROBE study design attempts to answer the question whether CN has an impact on overall survival outcomes in RCC within the context of immune checkpoint-based combination regimens. The study requires starting with systemic therapy; any one of the FDA approved immunotherapy-based regimens at the time the study was activated are permitted. The disease status and response are evaluated at 9–12 weeks of therapy and then consented patients are randomized 1:1 to receive CN or to continue systemic therapy. The patients who have rapid disease progression are considered ineligible for randomization as they need a switch in systemic therapy. Both groups should continue systemic therapy as long as they are tolerating the treatment and continuing to derive clinical benefit. Quality-of-life, tumor genomic testing, microbiome, radiomics and circulating tumor DNA assessments as predictive biomarkers are planned as study correlatives. The study hypothesis is that CN will improved OS in synchronous metastatic RCC when surgery is performed after starting systemic immune checkpoint-based combination therapy. A potential mechanism leading to improved survival is the broader antigen spread and higher neoantigen load enabled by the primary tumor enhancing the efficacy of the immune therapy. CN after initial systemic therapy would help select the patient subset most likely to benefit and will potentially enable eradication of immune resistant clones within the primary tumor.