Renal Cell Carcinoma of Variant Histology: New Biologic Understanding Leads to Therapeutic Advances

Renal cell carcinoma (RCC) is one of the 10 most commonly diagnosed solid tumors. Most RCCs are histologically defined as clear cell, comprising approximately 75% of diagnoses. However, the remaining RCC cases are composed of a heterogeneous combination of diverse histopathologic subtypes, each with unique pathogeneses and clinical features. Although the therapeutic approach to both localized and metastatic RCCs has dramatically changed, first with the advent of antiangiogenic targeted therapies and more recently with the approval of immune checkpoint inhibitor (ICI)-based combinations, these advances have primarily benefited the clear cell RCC patient population. As such, there remains critical gaps in the optimization of treatment regimens for patients with non-clear cell, or variant, RCC histologies. Herein, we detail recent advances in understanding the biology of RCC with variant histology and how such findings have guided novel clinical studies investigating precision oncology approaches for these rare subtypes. Among the most common variant histology RCCs are papillary RCC, comprising approximately 15%-20% of all diagnoses. Although a histopathologically diverse subset of tumors, papillary RCC is canonically associated with amplification of the MET protooncogene; recently completed and ongoing trials have investigated MET-directed therapies for this patient population. Finally, we discuss the unique biology of RCC with sarcomatoid dedifferentiation and the recent clinical findings detailing its paradoxical sensitivity to ICIs.

Barriers to Clinical Trial Implementation Among Community Care Centers

Importance

While an overwhelming majority of patients diagnosed with cancer express willingness to participate in clinical trials, only a fraction will enroll onto a research protocol.

Objective

To identify critical barriers to trial enrollment to translate findings into actionable practice changes that increase cancer clinical trial enrollment.

Design, Setting, and Participants

This survey study included designated site contacts at oncology practices with teams who were highly involved with the Association of Community Cancer Centers (ACCC) Community Oncology Research Institute (ACORI) clinical trials activities, all American Society of Clinical Oncology (ASCO)-ACCC collaboration pilot sites, and/or sites providing care to at least 25% African American and Hispanic residents. To determine participation trends among health care practices in oncology-focused research, identify barriers to clinical trial implementation and operation, and establish unmet needs for cancer clinics interested in trial participation, a 34-question survey was designed. Survey questions were defined within 3 categories: cancer center demographic characteristics, clinical trial characteristics, and referral practices. The survey was distributed through email and was open from June 20 through October 5, 2022.

Main Outcomes and Measures

Participation in and barriers to conducting oncology trials in different community oncology settings.

Results

The survey was distributed to 100 cancer centers, with completion by 58 centers (58%) across 25 states. Fifty-two centers (88%) reported that they conduct therapeutic clinical trials, of which 33 (63%) were from urban settings, 11 (21%) were from suburban settings, and 8 (15%) were from rural settings. Only 25% of rural practices (2 of 8) offered phase 1 trials, compared with 67% of urban practices (22 of 33) (P = .01). Respondents noted challenges in conducting research, including patient recruitment (27 respondents [52%]), limited staffing (27 [52%]), and nonrelevant trials for their patient population (25 [48%]). Among sites not offering therapeutic trials, barriers to research conduct included limited infrastructure, funding, and staffing. Most centers (46 of 58 [79%]) referred patients to outside centers for clinical trial enrollment, particularly in the context of late-stage disease and/or disease progression. Only 17 of these sites (37%) had established protocols for patient follow-up subsequent to outside referral.

Conclusions and Relevance

In this national survey study of barriers to clinical trial implementation, most sites offered therapeutic trials, but there were significant disparities in trial availability across care settings. Furthermore, fundamental deficiencies in trial support infrastructure limited research activity, including within programs currently conducting research as well as at sites interested in future clinical research opportunities. These results identify crucial unmet needs for oncology clinics to effectively offer clinical trials to patients seeking care.

Characterization of papillary and clear cell renal cell carcinoma through imaging mass cytometry reveals distinct immunologic profiles

Objective

To characterize and further compare the immune cell populations of the tumor microenvironment (TME) in both clear cell and papillary renal cell carcinoma (RCC) using heavy metal-labeled antibodies in a multiplexed imaging approach (imaging mass cytometry).

Materials and methods

Formalin-fixed paraffin-embedded (FFPE) baseline tumor tissues from metastatic patients with clear cell renal cell carcinoma (ccRCC) and papillary renal cell carcinoma (pRCC) were retrospectively requisitioned from an institutional biorepository. Pretreated FFPE samples from 33 RCC patients (10 ccRCC, 23 pRCC) were accessioned and stained for imaging mass cytometry (IMC) analysis. Clinical characteristics were curated from an institutional RCC database. FFPE samples were prepared and stained with heavy metal-conjugated antibodies for IMC. An 11-marker panel of tumor stromal and immune markers was used to assess and quantify cellular relationships in TME compartments. To validate our time-of-flight (CyTOF) analysis, we cross-validated findings with The Cancer Genome Atlas Program (TCGA) analysis and utilized the CIBERSORTx tool to examine the abundance of main immune cell types in pRCC and ccRCC patients.

Results

Patients with ccRCC had a longer median overall survival than did those with pRCC (67.7 vs 26.8 mo, respectively). Significant differences were identified in the proportion of CD4+ T cells between disease subtypes (ccRCC 14.1%, pRCC 7.0%, p<0.01). Further, the pRCC cohort had significantly more PanCK+ tumor cells than did the ccRCC cohort (24.3% vs 9.5%, respectively, p<0.01). There were no significant differences in macrophage composition (CD68+) between cohorts. Our results demonstrated a significant correlation between the CyTOF and TCGA analyses, specifically validating that ccRCC patients exhibit higher levels of CD4+ T cells (ccRCC 17.60%, pRCC 15.7%, p<0.01) and CD8+ T cells (ccRCC 17.83%, pRCC 11.15%, p<0.01). The limitation of our CyTOF analysis was the large proportion of cells that were deemed non-characterizable.

Conclusions

Our findings emphasize the need to investigate the TME in distinct RCC histological subtypes. We observed a more immune infiltrative phenotype in the TME of the ccRCC cohort than in the pRCC cohort, where a tumor-rich phenotype was noted. As practical predictive biomarkers remain elusive across all subtypes of RCC, further studies are warranted to analyze the biomarker potential of such TME classifications.

Targeted therapies: Expanding the role of FGFR3 inhibition in urothelial carcinoma

The management of urothelial carcinoma (UC) has rapidly advanced in recent years with new approvals for immune checkpoint inhibitors and antibody-drug conjugates. However, while many UC tumors contain potentially actionable mutations, the role for targeted small molecule inhibitors has been limited. One such target is the fibroblast growth factor receptor (FGFR) family of proteins. Activating mutations and amplifications of FGFR3 are common in UC with higher incidences seen in upper tract as compared to lower tract disease. Consequently, multiple FGFR-directed targeted therapies have been developed and trialed in both UC and other solid tumors harboring FGFR mutations. At current, erdafitinib, an inhibitor of FGFR1-4, is the only approved targeted therapy in metastatic UC following the BLC2001 study, which demonstrated a 49% overall response rate in patients with UC harboring an FGFR3 mutation. Additional FGFR-directed agents also continue to be investigated across multiple disease stages in FGFR-mutated UC including infigratinib, rogaratinib, and AZD4547, among others. Ongoing trials are combining these agents with immune checkpoint inhibitors and chemotherapy regimens. The precision medicine revolution has begun in UC, and FGFR3 inhibitors are leading the charge toward a more personalized, biomarker-driven treatment paradigm.

Characterizing the relationships between tertiary and community cancer providers: Results from a survey of medical oncologists in Southern California

BACKGROUND

Tertiary cancer centers offer clinical expertise and multi-modal approaches to treatment alongside the integration of research protocols. Nevertheless, most patients receive their cancer care at community practices. A better understanding of the relationships between tertiary and community practice environments may enhance collaborations and advance patient care.

METHODS

A 31-item survey was distributed to community and tertiary oncologists in Southern California using REDCap. Survey questions assessed the following attributes: demographics and features of clinical practice, referral patterns, availability and knowledge of clinical trials and precision medicine, strategies for knowledge acquisition, and integration of community and tertiary practices.

RESULTS

The survey was distributed to 98 oncologists, 85 (87%) of whom completed it. In total, 52 (61%) respondents were community practitioners and 33 (38%) were tertiary oncologists. A majority (56%) of community oncologists defined themselves as general oncologists, whereas almost all (97%) tertiary oncologists reported a subspecialty. Clinical trial availability was the most common reason for patient referrals to tertiary centers (73%). The most frequent barrier to tertiary referral was financial considerations (59%). Clinical trials were offered by 97% of tertiary practitioners compared to 67% of community oncologists (p = 0.001). Most oncologists (82%) reported only a minimal-to-moderate understanding of clinical trials available at regional tertiary centers.

CONCLUSIONS

Community oncologists refer patients to tertiary centers primarily with the intent of clinical trial enrollment; however, significant gaps exist in their knowledge of trial availability. Our results identify the need for enhanced communication and collaboration between community and tertiary providers to expand patients' access to clinical trials.

Learning from BISCAY: The future of biomarker-based trial design in bladder cancer

A recent article in Nature Medicine explored the combination of immunotherapy with multiple distinct targeted therapies in patients with metastatic urothelial cancer, employing a biomarker-driven approach. Herein, we discuss the merits of this ambitious study and highlight the need for larger biomarker-based randomized trials to arrive at definitive clinical conclusions.

Complementary Role of Circulating Tumor DNA Assessment and Tissue Genomic Profiling in Metastatic Renal Cell Carcinoma

PURPOSE

The role of circulating cell-free tumor DNA (ctDNA) as an adjunct to tissue genomic profiling is poorly defined in metastatic renal cell carcinoma (mRCC). In this study, we aim to validate previous findings related to genomic alteration (GA) frequency in ctDNA and determine the concordance between ctDNA and tissue-based profiling in patients with mRCC.

EXPERIMENTAL DESIGN

Results of 839 patients with mRCC who had ctDNA assessment with a Clinical Laboratory Improvement Amendments (CLIA)-certified ctDNA assay between November 2016 and December 2019 were collected. Tissue-based genomic profiling was collected when available and concordance analysis between blood- and tissue-based testing was performed.

RESULTS

ctDNA was assessed in 839 patients (comprising 920 samples) with mRCC. GAs were detected in 661 samples (71.8%). Tissue-based GAs were assessed in 112 patients. Limiting our analyses to a common 73-/74-gene set and excluding samples with no ctDNA detected, a total of 228 mutations were found in tissue and blood. Mutations identified in tissue (34.7%; 42/121) were also identified via ctDNA, whereas 28.2% (42/149) of the mutations identified in liquid were also identified via tissue. Concordance between ctDNA and tissue-based profiling was inversely related to the time elapsed between these assays.

CONCLUSIONS

This study confirms the feasibility of ctDNA profiling in the largest mRCC cohort to date, with ctDNA identifying multiple actionable alterations. It also demonstrates that ctDNA and tissue-based genomic profiling are complementary, with both platforms identifying unique alterations, and confirms that the frequency of unique alterations increases with greater temporal separation between tests.

Race/Ethnicity and Survival in Metastatic Renal Cell Carcinoma: Outcomes for Patients Receiving First Line Targeted Therapies

BACKGROUND: No study to date has assessed the relationship between treatment-specific therapeutic outcomes and race/ethnicity in metastatic renal cell carcinoma (mRCC). As targeted therapies have formed the backbone of first-line treatment options for mRCC until very recently, we assessed the relationship between race/ethnicity and targeted therapy-related outcomes in mRCC. OBJECTIVE: To retrospectively compare response rates and survival outcomes across ethnicities in patients who received first-line targeted therapies for mRCC. METHODS: Patients with mRCC receiving a first-line targeted therapy were identified from an institutional database encompassing consecutive patients treated between 2009 and 2019. Patient demographics, clinical characteristics and survival outcomes were recorded. The racial/ethnic groups included for analysis were Caucasian American, Hispanic American, and Asian American. Survival and response outcomes including progression-free survival (PFS), overall survival (OS), objective response rate (ORR) and disease control rate (DCR) were calculated and compared across ethnic groups using Kaplan-Meier method and Chi-square test, respectively. RESULTS: In total, 295 patients were included for analysis. There were 184 (62.4%) Caucasian American patients, 82 (27.8%) Hispanic American patients, and 29 (9.8%) Asian American patients. No statistically significant differences in PFS nor OS were found between groups (PFS: 5.6 vs. 4.7 vs. 4.7 months, respectively) (OS: 32 vs. 31.7 vs. 51.7 months, respectively). No significant difference was found in ORR nor DCR across groups. Univariate cox regression analyses demonstrated no independent effect of race/ethnicity on PFS or OS. CONCLUSIONS: The apparent lack of differences in treatment-related outcomes across racial/ethnic groups is encouraging. However, further validation is required in larger series.

Stool Microbiome Profiling of Patients with Metastatic Renal Cell Carcinoma Receiving Anti-PD-1 Immune Checkpoint Inhibitors

Preclinical models and early clinical data suggest an interplay between the gut microbiome and response to immunotherapy in solid tumors including metastatic renal cell carcinoma (mRCC). We sought to characterize the stool microbiome of mRCC patients receiving a checkpoint inhibitor (CPI) and to assess treatment-related changes in microbiome composition over the course of CPI therapy. Stool was collected from 31 patients before initiation of nivolumab (77%) or nivolumab plus ipilimumab (23%) therapy, of whom 58% experienced clinical benefit. Greater microbial diversity was associated with clinical benefit from CPI therapy (p =  0.001), and multiple species were associated with clinical benefit or lack thereof. Temporal profiling of the microbiome indicated that the relative abundance of Akkermansia muciniphila increased in patients deriving clinical benefit from CPIs. This study substantiates results from previous CPI-related microbiome profiling studies in mRCC. Temporal changes in microbiome composition suggest potential utility in modulating the microbiome for more successful CPI outcomes. PATIENT SUMMARY: We compared the composition and diversity of the gut microbiome in patients receiving immunotherapy for renal cell carcinoma. We found that higher microbial diversity is associated with better treatment outcomes. Treatment response is characterized by changes in microbial species over the course of treatment.

Abstract 5426: Genomic and immunohistochemical characterization of patients with advanced papillary renal cell carcinoma: Focus on exceptional responders

Background: Approximately 10-15% of patients with renal cell carcinoma (RCC) demonstrate papillary histology. Unfortunately for patients with advanced disease, there is no standard therapy for papillary RCC (pRCC). Herein, we provide detailed biologic characterization of patients with pRCC who have achieved exceptional responses to either targeted therapy or checkpoint inhibition.

Methods: Patients with pRCC were identified from an institutional database. Demographic and treatment-related data were compiled. Genomic characterization using CLIA-certified next-generation sequencing (NGS) platforms (FoundationOne; Foundation Medicine, Cambridge, MA or GEM ExTra: Ashion/TGen, Phoenix, AZ) was performed when deemed clinically relevant; this data was used to characterize the frequency of relevant genomic alterations (GAs) in this subset. Archived tissue was obtained when available and immunohistochemical staining was performed for CD4, CD8, CD11b and other markers to characterize T-cell subtype. Staining for MET, ALK and other protooncogenes was also performed and the spatial relationship between these proteins and immune cells was characterized.

Results: 64 pts with pRCC were identified (50:14 M:F). By International Metastatic RCC Database Consortium (IMDC) criteria, 3 were good risk, 42 were intermediate/poor risk, and 19 were considered unevaluable. Patients received a median of two lines of therapy (range, 1-7). The most common genomic alterations encountered among fifteen patients with available NGS profiling were BAP1 (20%) and TERT (20%). Three patients with ALK mutations were identified – each was treated with FDA approved ALK-inhibitors and all had a response to therapy, with a median progression-free survival (PFS) of 9.65 months (range, 1.25–23.47). Two patients with MET mutations were identified. Fifteen patients received an immune-checkpoint inhibitor as part of their care – eight (53%) experienced a PFS of greater than three months (median PFS, 3.1 months; range, 0.25–43.4). 30 patients received a MET-directed therapy (median PFS, 2.8 months; range, 0.4–29.9), including both patients with recorded MET GAs (PFS of 5.3 and 7.87 months, respectively), and 41 patients received a Vascular Endothelial Growth Factor Tyrosine Kinase Inhibitor (VEGF-TKI) (median PFS, 4.2 months; range, 0.33–134.47). In total, fifteen patients achieved an exceptional response (&gt;10 months) to therapy. Six such patients also had NGS data and tissue available for immunohistochemical characterization. Immunohistochemical characterization will be reported at the meeting.

Conclusions: Our results indicate that genomic profiling can yield actionable targets in pRCC. Matching these targets to relevant targeted therapies produces clinically meaningful responses.

Citation Format: Nicholas J. Salgia, Nazli Dizman, Isa Mambetsariev, Tamara Mirzapoiazova, Dan Zhao, Prakash Kulkarni, Ravi Salgia, Sumanta K. Pal. Genomic and immunohistochemical characterization of patients with advanced papillary renal cell carcinoma: Focus on exceptional responders [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5426.

Tivozanib in renal cell carcinoma: a new approach to previously treated disease

Targeted therapies have been a mainstay of the renal cell carcinoma (RCC) treatment paradigm for the better part of two decades. Multikinase inhibitors of the vascular endothelial growth factor receptor tyrosine kinases (VEGF-TKIs) comprise nearly all targeted therapies in RCC, having been prospectively tested through large, multi-institutional phase III trials. Tivozanib is a VEGF-TKI with high selectivity for VEGF receptors 1–3. Tivozanib has been under investigation for nearly 15 years, with a robust portfolio of preclinical and clinical data. This review seeks to characterize tivozanib within the context of RCC by highlighting preclinical and early clinical trials alongside the phase III trials in RCC, TIVO-1, and TIVO-3. We also aim to explore further trials of tivozanib, whether in combination with other agents and/or in differing disease settings, while providing insight into the utility of tivozanib as a clinical tool for the management of RCC.

A drug delivery perspective on intratumoral-immunotherapy in renal cell carcinoma

In less than 5years immune checkpoint inhibitors (ICI) went from first FDA approval to become first-line options in advanced renal cell carcinoma. Despite that many patients have benefited from ICI, a significant fraction of individuals are refractory to these new immunological treatments. In this review, we discussed using intratumoral (i.t.) route of drug administration as an alternative to systemic therapy to increase the response rates and to circumvent potential drug-induced systemic adverse events. We provided a historic account of i.t. drug treatments in cancer and reviewed the contemporary experience in local drug delivery. We discussed the potential for enhancing the therapeutic impact of ICI by leveraging hydrogels as drug delivery vehicles and presented an outlook for implementing i.t. in renal cell carcinoma.