Biphasic components of sarcomatoid clear cell renal cell carcinomas are molecularly similar to each other, but distinct from, non-sarcomatoid renal carcinomas

Localised non-metastatic sarcomatoid renal cell carcinoma: a 31-year externally verified study

OBJECTIVE

To evaluate post-nephrectomy outcomes and predictors of cancer-specific survival (CSS) between patients with localised sarcomatoid renal cell carcinoma (sRCC) and those with Grade 4 RCC (non-sRCC), as most sRCC research focuses on advanced or metastatic disease with limited studies analysing outcomes of patients with localised non-metastatic sRCC.

PATIENTS AND METHODS

A total of 564 patients with localised RCC underwent partial or radical nephrectomy between June 1988 to March 2019 for sRCC (n = 204) or World Health Organization/International Society of Urological Pathology Grade 4 non-sRCC (n = 360). The CSS at every stage between groups was assessed. Phase III ASSURE clinical trial data were used to externally validate the CSS findings. The Mann-Whitney U-test and chi-squared test compared outcomes and the Kaplan-Meier method evaluated CSS, overall survival (OS) and recurrence-free survival. Clinicopathological features associated with RCC death were evaluated using Cox proportional hazards regression.

RESULTS

The median follow-up was 31.5 months. The median OS and CSS between the sRCC and Grade 4 non-sRCC groups was 45 vs 102 months and 49 vs 152 months, respectively (P < 0.001). At every stage, sRCC had worse CSS compared to Grade 4 non-sRCC. Notably, pT1 sRCC had worse CSS than pT3 Grade 4 non-sRCC. Negative predictors of CSS were sarcomatoid features, non-clear cell histology, positive margins, higher stage (pT3/pT4), and use of minimally invasive surgery (MIS). ASSURE external verification showed worse CSS in patients with sRCC (hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.12-2.36; P = 0.01), but not worse outcomes in MIS surgery (HR 1.39, 95% CI 0.75-2.56; P = 0.30).

CONCLUSIONS

Localised sRCC had worse CSS compared to Grade 4 non-sRCC at every stage. Negative survival predictors included positive margins, higher pathological stage, use of MIS, and non-clear cell histology. sRCC is an aggressive variant even at low stages requiring vigilant surveillance and possible inclusion in adjuvant therapy trials.

Establishment and validation of a nomogram to select patients with metastatic sarcomatoid renal cell carcinoma suitable for cytoreductive radical nephrectomy

Introduction

Metastatic renal cell carcinoma (mRCC) with sarcomatoid features has a poor prognosis. Cytoreductive radical nephrectomy (CRN) can improve prognosis, but patient selection is unclear. This study aimed to develop a prediction model for selecting patients suitable for CRN.

Materials and methods

Patients with a diagnosis of mRCC with sarcomatoid features in the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015 were retrospectively reviewed. CRN benefit was defined as a survival time longer than the median overall survival (OS) in patients who did not receive CRN. A prediction nomogram was established and validated using the SEER cohort (training and internal validation) and an external validation cohort.

Results

Of 900 patients with sarcomatoid mRCC, 608 (67.6%) underwent CRN. OS was longer in the CRN group than in the non-CRN group (8 vs. 6 months, hazard ratio (HR) = 0.767, p = 0.0085). In the matched CRN group, 124 (57.7%) patients survived >6 months after the surgery and were considered to benefit from CRN. Age, T-stage, systematic therapy, metastatic site, and lymph nodes were identified as independent factors influencing OS after CRN, which were included in the prediction nomogram. The monogram performed well on the training set (area under the receiver operating characteristic (AUC) curve = 0.766, 95% confidence interval (CI): 0.687-0.845), internal validation set (AUC = 0.796, 95% CI: 0.684-0.908), and external validation set (AUC = 0.911, 95% CI: 0.831-0.991).

Conclusions

A nomogram was constructed and validated with good accuracy for selecting patients with sarcomatoid mRCC suitable for CRN.

Sarcomatoid renal cell carcinoma: biology, natural history and management

Sarcomatoid dedifferentiation is an uncommon feature that can occur in most histological subtypes of renal cell carcinomas (RCCs) and carries a decidedly poor prognosis. Historically, conventional treatments for sarcomatoid RCCs (sRCCs) have shown little efficacy, and median survival is commonly 6–13 months. Despite being first described in 1968, the mechanisms driving sarcomatoid dedifferentiation remain poorly understood, and information and treatment options available to physicians and patients are limited. When diagnosed at an early stage, surgical intervention remains the treatment of choice. However, preoperative identification through routine imaging or biopsy is unreliable and most patients present with advanced disease and systemic symptoms. For these patients, the role of cytoreductive nephrectomy is disputed. The expansion of immunotherapies approved for RCCs has generated a search for biomarkers that might be indicative of treatment response in sRCCs, although a proven effective systemic agent remains elusive. PDL1 expression is increased in sarcomatoid dedifferentiated renal tumours, which suggests that patients with sRCCs could benefit from PD1 and/or PDL1 immune checkpoint blockade therapy. Treatment outcomes for sarcomatoid tumours have remained relatively consistent compared with other RCCs, but further investigation of the tumour–immune cell microenvironment might yield insights into further therapeutic possibilities.

In this Review, Blum et al. summarize the current knowledge on sarcomatoid renal cell carcinoma, a diagnosis characterized by the presence of sarcomatoid dedifferentiation and a poor prognosis. They discuss the origin, presentation, molecular biology and treatment of this disease.

Sarcomatoid dedifferentiation is not considered to be a unique histological subtype of renal cell carcinomas (RCCs); rather, it can be present within any subtype of RCCs.

Sarcomatoid dedifferentiation appears in ~4% of all RCCs, but is present in ~20% of all metastatic RCCs. According to WHO guidelines, any RCC with sarcomatoid dedifferentiation is a WHO–International Society of Urological Pathology grade 4 lesion.

Sarcomatoid dedifferentiation is often heterogeneously present within RCCs, making routine imaging and biopsy unreliable for preoperative detection. Surgical resection for localized disease is the standard of care, with subsequent close monitoring of patients following surgery.

In patients with metastatic disease, conventional therapies such as surgery and systemic agents have been ineffective and overall 5-year survival remains at 23.5–33%.

Previous genomic analyses have failed to identify definitive mutational drivers of disease. However, sarcomatoid RCCs (sRCCs) have been shown to have higher PD1 and PDL1 expression than other subtypes of RCCs. Newer combinations of immune checkpoint inhibitor immunotherapies could yield improved responses and outcomes.

Studies investigating sRCCs are limited by patient numbers owing to the low incidence of sRCCs and their advanced stage at presentation. Multi-institutional efforts to establish a consensus on treatment recommendations based on highly powered data are essential.

Genetic Alterations in Renal Cancers: Identification of The Mechanisms Underlying Cancer Initiation and Progression and of Therapeutic Targets

Renal cell cancer (RCC) involves three most recurrent sporadic types: clear-cell RCC (70-75%, CCRCC), papillary RCCC (10-15%, PRCC), and chromophobe RCC (5%, CHRCC). Hereditary cases account for about 5% of all cases of RCC and are caused by germline pathogenic variants. Herein, we review how a better understanding of the molecular biology of RCCs has driven the inception of new diagnostic and therapeutic approaches. Genomic research has identified relevant genetic alterations associated with each RCC subtype. Molecular studies have clearly shown that CCRCC is universally initiated by Von Hippel Lindau (VHL) gene dysregulation, followed by different types of additional genetic events involving epigenetic regulatory genes, dictating disease progression, aggressiveness, and differential response to treatments. The understanding of the molecular mechanisms that underlie the development and progression of RCC has considerably expanded treatment options; genomic data might guide treatment options by enabling patients to be matched with therapeutics that specifically target the genetic alterations present in their tumors. These new targeted treatments have led to a moderate improvement of the survival of metastatic RCC patients. Ongoing studies based on the combination of immunotherapeutic agents (immune check inhibitors) with VEGF inhibitors are expected to further improve the survival of these patients.

Molecular characteristics and markers of advanced clear cell renal cell carcinoma: Pitfalls due to intratumoral heterogeneity and identification of genetic alterations associated with metastasis

OBJECTIVES

To identify clear cell renal cell carcinoma-related gene mutations potentially associated with aggressive disease, sarcomatoid differentiation or poor prognosis.

METHODS

We carried out genomic analysis of 217 tumor foci from 25 patients with conventional clear cell renal cell carcinoma (14 patients), clear cell renal cell carcinoma with sarcomatoid differentiation (six patients) and non-clear cell renal cell carcinoma (five patients). Each tumor nodule on the tissue block that corresponded to the same focus on the slide was separated from the normal parenchyma and other histologically distinct areas of tumor. The isolated tumor foci were used for subsequent analyses and sequencing. Deoxyribonucleic acid from the formalin-fixed paraffin-embedded tissues was extracted. Multiplex bar-coded polymerase chain reaction amplification was carried out using next-generation sequencing libraries.

RESULTS

Overall, 67 protein alterations, including amino acid alterations, frame shifts and splice site mutations in seven genes were identified in the cohort of renal cell carcinoma tumors included in this study. Fewer patients with clear cell renal cell carcinoma with sarcomatoid differentiation had clear cell renal cell carcinoma-related mutations in comparison with patients with conventional clear cell renal cell carcinoma. Additionally, the average number of unique clear cell renal cell carcinoma-related protein alterations per patient was significantly lower in clear cell renal cell carcinoma with sarcomatoid differentiation than in conventional clear cell renal cell carcinoma. Mutations in PBRM1 were identified in a higher proportion of patients with high-grade tumors (World Health Organization/International Society of Urological Pathology grade 4) and in the primary tumors of six of 10 (60%) patients with metastatic disease.

CONCLUSIONS

Although there are pitfalls due to intratumoral heterogeneity and sampling bias, mutations in PBRM1 may be associated with metastasis and aggressive disease in clear cell renal cell carcinoma.

Sarcomatoid Dedifferentiation in Renal Cell Carcinoma: From Novel Molecular Insights to New Clinical Opportunities

Sarcomatoid features in renal cell carcinoma (RCC) have long been associated with dismal prognosis and poor response to therapy, while biological mechanisms underpinning sarcomatoid dedifferentiation remained obscure. Several efforts have been conducted to break down the molecular profile of sarcomatoid RCC and investigate different targeted therapeutic approaches. Mutations enriched for in sarcomatoid RCC involve, notably, TP53, BAP1, cell cycle, and chromatin-remodeling genes. The immunological landscape of these tumors is also gradually being uncovered, showing frequent expression of programmed cell death ligand-1 (PD-L1) and high levels of tumor-infiltrating lymphocytes. These features may be major determinants for the activity of immune checkpoint inhibitors in this population, which has been confirmed by retrospective studies and subgroup analyses of large randomized phase 3 trials. Combinations based on PD-1/PD-L1 inhibition have demonstrated response rates and complete responses in >50% and >10% of patients in the first-line metastatic setting, respectively, with median overall survival exceeding two years. This remarkable improvement in outcomes effectively establishes immune checkpoint inhibitor combinations as a new standard of care in patients with sarcomatoid RCC. New research fields, including epigenetic regulations and tumor-microenvironment interactions, may further sharpen understanding of sarcomatoid RCC and advance therapeutic developments.

Epidemiology, biology and treatment of sarcomatoid RCC: current state of the art

Long recognized to confer an extremely poor prognosis, sarcomatoid dedifferentiation of renal cell carcinoma (sRCC) is a tumor phenotype that is finally beginning to be better understood on the molecular and genetic levels. With an overall incidence that ranges from 1 to 32% depending on associated RCC subtype, the survival of sarcomatoid RCC patients rarely exceeds 2 years. The main reasons for its poor outcome include its aggressive biology, its tendency to present at an advanced or metastatic stage at the time of diagnosis, its high rate of tumor recurrence after nephrectomy, and its limited response to systemic therapies. Molecular pathology studies suggest that sarcomatoid dedifferentiation originates from a focal epithelial-mesenchymal transition (EMT) arising in the carcinomatous component of the tumor. It is hoped that the growing understanding of the molecular biology of sRCC will soon make it possible to adapt treatments based on the identification of actionable tumor alterations. The deliberate inclusion of these patients in the multicenter clinical trials of immune, targeted and combination therapies is a necessary next step in pioneering future treatment strategies.

Sarcomatoid Renal Cell Carcinoma Has a Distinct Molecular Pathogenesis, Driver Mutation Profile, and Transcriptional Landscape

Purpose: Sarcomatoid renal cell carcinoma (SRCC) ranks among the most aggressive clinicopathologic phenotypes of RCC. However, the paucity of high-quality, genome-wide molecular examinations of SRCC has hindered our understanding of this entity.Experimental Design: We interrogated the mutational, copy number, and transcriptional characteristics of SRCC and compared these data with those of nonsarcomatoid RCC (RCC). We evaluated whole-exome sequencing, single-nucleotide polymorphism, and RNA sequencing data from patients with SRCC (n = 65) and RCC (n = 598) across different parent RCC subtypes, including clear-cell RCC, papillary RCC, and chromophobe RCC subtypes.Results: SRCC was molecularly discrete from RCC and clustered according to its parent RCC subtype, though with upregulation of TGFβ signaling across all subtypes. The epithelioid (E-) and spindled (S-) histologic components of SRCC did not show differences in mutational load among cancer-related genes despite a higher mutational burden in S-. Notably, sarcomatoid clear-cell RCC (SccRCC) showed significantly fewer deletions at 3p21-25, a lower rate of two-hit loss for VHL and PBRM1, and more mutations in PTEN, TP53, and RELN compared with ccRCC. A two-hit loss involving VHL predicted for ccRCC and a better prognosis, whereas mutations in PTEN, TP53, or RELN predicted for SccRCC and worse prognosis.Conclusions: SRCC segregates by parent subtype, and SccRCC has a fundamentally different early molecular pathogenesis, usually lacking the classic 3p21-25 deletion and showing distinctive mutational and transcriptional profiles. These features prompt a more precise molecular classification of RCC, with diagnostic, prognostic, and therapeutic implications. Clin Cancer Res; 23(21); 6686-96. ©2017 AACRSee related commentary by Bergerot et al., p. 6381.