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.
Background: SET domain-containing protein 2 (SETD2) is commonly mutated in renal cell carcinoma. SETD2 methylates histone H3 as well as a growing list of non-histone proteins.
Objective: Initially, we sought to explore SETD2-dependent changes in lysine methylation of proteins in proximal renal tubule cells. Subsequently, we focused on changes in lysine methylation of the translation elongation factor eEF1A1.
Methods: To accomplish these objectives, we initially performed a systems-wide analysis of protein lysine-methylation and expression in wild type (WT) and SETD2-knock out (KO) kidney cells and later focused our studies on eEF1A1 as well as the expression of lysine methyltransferases that regulate its lysine methylation.
Results: We observed decreased lysine methylation of the translation elongation factor eEF1A1. EEF1AKMT2 and EEF1AKMT3 are known to methylate eEF1A1, and we show here that their expression is dependent on SET-domain function of SETD2. Globally, we observe differential expression of hundreds of proteins in WT versus SETD2-KO cells, including increased expression of many involved in protein translation. Finally, we observe decreased progression free survival and loss of EEF1AKMT2 gene expression in SETD2-mutated tumors predicted to have loss of function of the SET domain.
Conclusion: Overall, these data suggest that SETD2-mutated ccRCC, via loss of enzymatic function of the SET domain, displays dysregulation of protein translation as a potentially important component of the transformed phenotype.

