The Evolving Role of Rituximab in Adult Minimal Change Glomerulopathy.

BACKGROUND: Minimal-change glomerulopathy is defined histologically by the presence of normal glomeruli on light microscopy and diffuse podocyte effacement on electron microscopy. Although effective in children, corticosteroid treatment in adults is more variable and time to response can be prolonged. Data to support rituximab use in adults with corticosteroid-dependent or resistant minimal-change glomerulopathy are limited. Here, we describe the clinical course of adults with corticosteroid-dependent or -resistant minimal-change glomerulopathy who received rituximab. METHODS: Demographic and clinical data were collected and analyzed from all adult patients with native kidney, biopsy-proven, minimal-change glomerulopathy who were administered rituximab between 2009 and 2014 and cared for at the UNC Kidney Center. RESULTS: Ten patients with corticosteroid-resistant (n = 5) or corticosteroid-dependent (n = 5) idiopathic minimal-change glomerulopathy were treated with rituximab between 2009 and 2014. Rituximab treatment induced remission in all 10 patients with a median time to remission of 2 months. The median time from rituximab to corticosteroid discontinuation was 3.5 months. The median remission time was 29 months and follow-up time was 39.5 months. No serious adverse events attributable to rituximab were observed. CONCLUSION: Rituximab induced remission in all patients with corticosteroid-dependent or -resistant minimal-change glomerulopathy, and may hold great therapeutic potential with good efficacy and minimal toxicity. Mounting evidence implies that a well-conducted randomized controlled clinical trial using rituximab in adults with minimal-change glomerulopathy in both corticosteroid-resistant and corticosteroid-dependent patients is warranted.

Thrombosis Rates and Genetic Thrombophilia Risk Among Patients With Advanced Germ Cell Tumors Treated With Chemotherapy.

INTRODUCTION: Men with advanced germ cell tumors (GCT) treated with chemotherapy are at high risk of venous thromboembolism (VTE). Predictors of VTE may identify patients who would benefit from prophylactic anticoagulation. PATIENTS AND METHODS: Men with advanced GCT (Stage IS, II, III) treated with chemotherapy were identified at 2 centers. High genomic risk was defined from a 5 single nucleotide polymorphism (SNP) germline panel. Logistic regression was used to evaluate the impact of genomic risk on VTE within 6 months of chemotherapy initiation. Orthogonal Projection to Latent Structures Discriminant Analysis (OPLS-DA) was used to build models to predict VTE based on clinical variables and an 86 SNP panel. RESULTS: This 123-patient cohort experienced a VTE rate of 26% with an incidence of high genomic risk of 21%. Men with high genomic risk did not have a significantly higher VTE rate (31%, 8/26) than men with low genomic risk (25%, 24/97), unadjusted OR 1.4 (95% CI 0.5-3.5, P = .54). Incorporation of clinical variables (Khorana score, N3 status and elevated LDH) resulted in adjusted OR 2.1 (95% CI 0.7-6.5, P = .18). A combined model using clinical variables and 86 SNPs performed similarly (AUC 0.77) compared to clinical variables alone (AUC 0.72). CONCLUSIONS: A previously established 5-SNP panel was not associated with VTE among patients with GCT receiving chemotherapy. However, multivariable models based on clinical variables alone warrant further validation to inform prophylactic anticoagulation strategies.

RNA-Based Homologous Recombination Deficiency Signature Detects Homologous Recombination Deficiency-RNA+ Patients With and Without Homologous Recombination Repair Gene Pathogenic Alterations in Men With Prostate Cancer.

PURPOSE: Homologous recombination deficiency (HRD) is a well-described phenotype of some prostate cancers; however, current biomarkers for HRD are imperfect and rely on detection of single gene alterations in the homologous recombination repair (HRR) pathway, which may not capture the complexity of HRD biology. RNA signature-based methods of HRD identification present a potentially dynamic assessment of the HRD phenotype; however, its relationship with HRR gene alterations is not well characterized in prostate cancer. METHODS: A HRD assay on the basis of an RNA signature associated with biallelic BRCA1/2 loss was applied to a retrospective cohort study of 985 men with prostate cancer analyzed on the Tempus xT platform. HRD status was defined by a binary threshold on a continuous scale. RESULTS: In this cohort, of the 126 (13%) patients found to be HRD+ by RNA signature (HRD-RNA+), 100 (79%) had no coexisting HRR gene alteration. Among samples with biallelic BRCA1/2 loss, 78% (7/9) were classified as HRD-RNA+, while 8% (2/25) of samples with BRCA1/2 monoallelic loss were HRD-RNA+. Biallelic and monoallelic ATM loss exhibited HRD-RNA+ at a lower prevalence: 6.7% (1/15) and 7.1% (1/14), respectively, compared with HRD-RNA+ prevalence among samples without any HRR gene loss (13%; 100/782). HRD-RNA+ was associated with a significantly higher prevalence of TP53 and AR gene alterations relative to HRD-RNA- after correction for multiple comparisons, 59% versus 39% (q = 0.003) and 23% versus 12% (q = 0.024), respectively. CONCLUSION: Use of an RNA-based HRD signature significantly expands the fraction of patients with prostate cancer who may derive benefit from poly (ADP-ribose) polymerase inhibitors (PARPis) compared with using HRR gene mutations alone. Further studies are needed to evaluate functional HRD significance and inform future usage as a predictive biomarker for PARPi selection.

Prognostic value of galectin-1 and galectin-3 expression in localized urothelial bladder cancer.

Background: Galectin-1 (Gal-1) and Galectin-3 (Gal-3) are carbohydrate binding proteins with a wide range of biological activity, including regulation of cellular adhesion, proliferation, and apoptosis in solid tumors. Prior small studies have reported that Gal-3 expression is associated with progression of disease in urothelial carcinoma (UC), from non-muscle invasive UC progression to muscle invasive UC. We assessed Gal-1 and Gal-3 protein expression H-score utilizing a tissue microarray (TMA) created from 301 cystectomy specimens. Methods: Immunohistochemistry for Gal-1 and Gal-3 was performed on TMA generated from tumor blocks from chemotherapy naïve cystectomy specimens. The variable of interest, H-score, was defined as the product of the percentage of cells staining positive (0-100) and intensity score (0-3) scored by a single pathologist. Survival end points were analyzed using Kaplan-Meier and Cox Proportional Hazards methods. Clinical data including Charlson Comorbidity Index (CCI), pathologic tumor (T) stage, tumor size, node stage, and surgical margins, were included in multivariable analysis. Results: We found that Gal-1 and Gal-3 expression correlated with intratumoral T stage (median Gal-1 H-score was 0 across non-invasive tissue types and 200 in invasive, P<0.01 and median Gal-3 score was 270 across non-invasive tissue types and 70 in invasive, P<0.01). However, the highest intratumoral H-score per cystectomy core did not independently predict for recurrence-free survival (RFS) (Gal-1: HR =1.02, P=0.44, Gal-3: HR =1.01, P=0.65) or OS (Gal-1: HR =1.02, P=0.44, Gal-3: HR =1.01, P=0.72) in this cohort. Significant intratumoral heterogeneity was present for both Gal-1 and Gal-3, with an average difference between the highest and lowest H score was 95 for Gal-1 and 109 for Gal-3 for cystectomy specimens with more than one biopsy. Conclusions: Gal-1 and Gal-3 H-score per bladder did not independently predict for RFS or OS. Intra-tumoral Gal-1/Gal-3 heterogeneity complicates the use of Gal-1 and Gal-3 expression as a prognostic biomarker. Future studies should consider the evaluation of serum and urinary galectins as an approach to mitigate tumor heterogeneity.

A phase 2 trial of avelumab in men with aggressive-variant or neuroendocrine prostate cancer.

BACKGROUND: Men with progressive neuroendocrine or aggressive-variant metastatic prostate cancer (NEPC/AVPC) have a poor prognosis and limited treatment options, and immunotherapy has not been tested in such patients. METHODS: We conducted an open label single center phase 2 trial (NCT03179410) of men with progressive NEPC/AVPC either defined by histology or AVPC criteria. Avelumab (10 mg/kg every 2 weeks) was administered until progression or unacceptable toxicity. The primary endpoint was overall response rate (ORR). Secondary endpoints included ORR, radiographic progression-free survival (rPFS), overall survival, and safety. Correlative studies included longitudinal peripheral blood immune phenotyping. The study was limited by the small number of patients enrolled and by the early termination due to COVID-19. RESULTS: A total of 15 men with AVPC/NEPC were enrolled. The median age was 71 (range 51-85 years), and men had received a median of two prior therapies (range 1-3). Median PSA was 54 ng/dl (range 0-393), and 73% of men had liver metastasis. The ORR with avelumab in this setting by iRECIST or RECIST 1.1 was 6.7%, including one patient (6.7%) with a complete remission (CR), 20% with stable disease, and 67% with progressive disease. The patient with the CR had an MSH2 somatic mutation and MSI-high NEPC with central nervous system metastases, and his CR remains durable off all therapy for 2 years. The median rPFS was 1.8 months (95% CI 1.6-3.6 months), and median overall survival was 7.4 months (85% CI 2.8-12.6 months). Safety was consistent with the known profile of avelumab. Phenotyping of peripheral immune subsets suggest enhanced CXCR2-dependent myeloid and T-cell responses in this extraordinary responder. CONCLUSIONS: While the study was terminated early due to slow enrollment at the onset of the COVID-19 pandemic and lower than anticipated objective response rate, PD-L1 inhibition with avelumab monotherapy showed poor efficacy in patients with microsatellite stable NEPC/AVPC. Immune profiling revealed enhanced CXCR2 positive immune cell activation in the one extraordinary responder, suggesting potential mechanisms for further immunotherapy development in this population.

Evaluation of tumor microenvironment and biomarkers of immune checkpoint inhibitor response in metastatic renal cell carcinoma.

BACKGROUND: Immunotherapy combinations including ipilimumab and nivolumab are now the standard of care for untreated metastatic renal cell carcinoma (mRCC). Biomarkers of response are lacking to predict patients who will have a favorable or unfavorable response to immunotherapy. This study aimed to use the OmniSeq transcriptome-based platform to develop biomarkers of response to immunotherapy. METHODS: Two cohorts of patients were retrospectively collected. These included an investigational cohort of patients with mRCC treated with immune checkpoint inhibitor therapy from five institutions, and a subsequent validation cohort of patients with mRCC treated with combination ipilimumab and nivolumab from two institutions (Duke Cancer Institute and Cleveland Clinic Taussig Cancer Center). Tissue-based RNA sequencing was performed using the OmniSeq Immune Report Card on banked specimens to identify gene signatures and immune checkpoints associated with differential clinical outcomes. A 5-gene expression panel was developed based on the investigational cohort and was subsequently evaluated in the validation cohort. Clinical outcomes including progression-free survival (PFS) and overall survival (OS) were extracted by retrospective chart review. Objective response rate (ORR) was assessed by Response Evaluation Criteria in Solid Tumors (RECIST) V.1.1. RESULTS: The initial investigation cohort identified 86 patients with mRCC who received nivolumab (80%, 69/86), ipilimumab/nivolumab (14%, 12/86), or pembrolizumab (6%, 5/86). A gene expression score was created using the top five genes found in responders versus non-responders (FOXP3, CCR4, KLRK1, ITK, TIGIT). The ORR in patients with high gene expression (GEhigh) on the 5-gene panel was 29% (14/48), compared with low gene expression (GElow) 3% (1/38, χ2 p=0.001). The validation cohort was comprised of 62 patients who received ipilimumab/nivolumab. There was no difference between GEhigh and GElow in terms of ORR (44% vs 38.5%), PFS (HR 1.5, 95% CI 0.58 to 3.89), or OS (HR 0.96, 95% CI 0.51 to 1.83). Similarly, no differences in ORR, PFS or OS were observed when patients were stratified by tumor mutational burden (high=top 20%), PD-L1 (programmed death-ligand 1) expression by immunohistochemistry or RNA expression, or CTLA-4 (cytotoxic T-lymphocytes-associated protein 4) RNA expression. The International Metastatic RCC Database Consortium (IMDC) risk score was prognostic for OS but not PFS. CONCLUSION: A 5-gene panel that was associated with improved ORR in a predominantly nivolumab monotherapy population of patients with mRCC was not predictive for radiographic response, PFS, or OS among patients with mRCC treated with ipilimumab and nivolumab.

The Association between a Decrease in On-Treatment Neutrophil-to-Eosinophil Ratio (NER) at Week 6 after Ipilimumab Plus Nivolumab Initiation and Improved Clinical Outcomes in Metastatic Renal Cell Carcinoma.

A lower baseline neutrophil-to-eosinophil ratio (NER) has been associated with improved responses to immune checkpoint inhibitors (ICI)-treated metastatic renal cell carcinoma (mRCC). This study investigated the decrease in NER at week 6 after ipilimumab/nivolumab (ipi/nivo) initiation and treatment responses in mRCC. A retrospective study of ipi/nivo-treated mRCC at two US academic cancer centers was conducted. A landmark analysis at week 6 was performed to assess the association between the change in NER and clinical responses (progression-free survival (PFS)/overall survival (OS)). Week 6 NER was modeled as a continuous variable, after log transformation (Ln NER), and a categorical variable by percent change. There were 150 mRCC patients included: 78% had clear cell histology, and 78% were IMDC intermediate/poor risk. In multivariable regression analysis, every decrease of 1 unit of Ln NER at week 6 was associated with improved PFS (adjusted hazard ratio (AHR): 0.78, p-value:0.005) and OS (AHR: 0.67, p-value: 0.002). When NER was modeled by percent change, decreased NER > 50% was associated with improved PFS (AHR: 0.55, p-value: 0.03) and OS (AHR: 0.37, p-value: 0.02). The decrease in week 6 NER was associated with improved PFS/OS in ipi/nivo-treated mRCC. Prospective studies are warranted to validate NER change as a biomarker to predict ICI responses.

Clinical outcomes in patients with metastatic renal cell carcinoma and brain metastasis treated with ipilimumab and nivolumab.

The combination of ipilimumab plus nivolumab (I+N) has greatly improved outcomes in patients with intermediate or poor-risk untreated metastatic renal cell carcinoma (mRCC). However, little is known about the outcomes of patients with brain metastasis (BrM) treated with I+N. A search was performed to retrospectively identify all patients with mRCC treated with I+N in the Duke Cancer Institute and the Cleveland Clinic Taussig Cancer Center, followed by a chart review. Patients were included if they had BrM at the time of I+N initiation. Cohort characteristics are summarized with descriptive statistics. Kaplan-Meier method was used to estimate overall survival (OS) and global, intracranial, and extracranial progression-free survival (PFS) for the cohort and log rank test was used to compare OS and PFS between patient groups. Radiographic response was categorized by RECIST. Fisher's exact test was used to correlate patient factors with radiographic response. From October 2017 to December 2020, 19 patients with BrM received I+N for mRCC with a median follow-up time of 27.1 months (range 15.0-35.6). By International Metastatic RCC Database Consortium (IMDC) risk criteria, 16% had favorable, 58% had intermediate, and 26% had poor-risk disease. 68% were systemic therapy naïve, and 77% of patients had clear cell histology. 95% had received local CNS directed therapy with surgery, radiotherapy, or both. The objective response rate was 44% (0% complete response) with three of six patients treated in the second line or greater setting experiencing a partial response. The median PFS was 7.6 months (95% CI 5.6 to 14.9). The median extracranial PFS was 8.5 months (95% CI 5.6 to 19.7), and median intracranial PFS was 14.7 months (95% CI 7.2 to not reached). No variables assessed were significantly associated with radiographic response (gender, IMDC risk, presence of bone metastasis, line of therapy, or presence of immune related adverse events). In our retrospective cohort of patients with mRCC with BrM, I+N, in combination with CNS-directed local therapy, appears to have clinical efficacy as previously described with responses seen beyond the first-line setting. Further investigation is warranted in this population given exclusion from prior clinical trials.

LRP1B mutations are associated with favorable outcomes to immune checkpoint inhibitors across multiple cancer types.

BACKGROUND: Low-density lipoprotein receptor-related protein 1b (encoded by LRP1B) is a putative tumor suppressor, and preliminary evidence suggests LRP1B-mutated cancers may have improved outcomes with immune checkpoint inhibitors (ICI). METHODS: We conducted a multicenter, retrospective pan-cancer analysis of patients with LRP1B alterations treated with ICI at Duke University, Johns Hopkins University (JHU) and University of Michigan (UM). The primary objective was to assess the association between overall response rate (ORR) to ICI and pathogenic or likely pathogenic (P/LP) LRP1B alterations compared with LRP1B variants of unknown significance (VUS). Secondary outcomes were the associations with progression-free survival (PFS) and overall survival (OS) by LRP1B status. RESULTS: We identified 101 patients (44 Duke, 35 JHU, 22 UM) with LRP1B alterations who were treated with ICI. The most common tumor types by alteration (P/LP vs VUS%) were lung (36% vs 49%), prostate (9% vs 7%), sarcoma (5% vs 7%), melanoma (9% vs 0%) and breast cancer (3% vs 7%). The ORR for patients with LRP1B P/LP versus VUS alterations was 54% and 13%, respectively (OR 7.5, 95% CI 2.9 to 22.3, p=0.0009). P/LP LRP1B alterations were associated with longer PFS (HR 0.42, 95% CI 0.26 to 0.68, p=0.0003) and OS (HR 0.62, 95% CI 0.39 to 1.01, p=0.053). These results remained consistent when excluding patients harboring microsatellite instability (MSI) and controlling for tumor mutational burden (TMB). CONCLUSIONS: This multicenter study shows significantly better outcomes with ICI therapy in patients harboring P/LP versus VUS LRP1B alterations, independently of TMB/MSI status. Further mechanistic and prospective validation studies are warranted.

Association of baseline neutrophil-to-eosinophil ratio with response to nivolumab plus ipilimumab in patients with metastatic renal cell carcinoma.

BACKGROUND: The identification of biomarkers to select patients with metastatic renal cell carcinoma (mRCC) most likely to respond to combination immunotherapy (IO) is needed. We sought to investigate an association of the baseline neutrophil-to-eosinophil ratio (NER) with outcomes to nivolumab plus ipilimumab for patients with mRCC. METHODS: We performed a retrospective review of patients with clear cell mRCC treated with nivolumab plus ipilimumab from Vanderbilt-Ingram Cancer Center and Duke Cancer Institute. Patients with prior receipt of immunotherapy and those without available baseline complete blood count with differential were excluded. Patients were divided into groups by the median baseline NER and analyzed for overall survival (OS), progression free survival (PFS), and objective response rate (ORR). Patients were also divided by median baseline neutrophil-to-lymphocyte ratio (NLR) and analyzed for clinical outcome. Further analyses of patients above/below the median NER and NLR were performed in subgroups of IMDC intermediate/poor risk, IMDC favorable risk, and treatment naïve patients. RESULTS: A total of 110 patients were included: median age was 61 years and 75% were treatment naïve. The median NER (mNER) at baseline was 26.4. The ORR was 40% for patients with mNER (OR 2.39, p = 0.04). The median PFS for patients with mNER (HR 0.50, p < 0.01). Median OS was not reached (NR) for patients with mNER (HR 0.31, p < 0.01). The median NLR (mNLR) was 3.42. While patients with mNLR group. CONCLUSIONS: A lower baseline NER was associated with improved clinical outcomes (PFS, OS, and ORR) in patients with mRCC treated with nivolumab plus ipilimumab, and prospective validation of the baseline NER as a predictive biomarker for response to immunotherapy-based combinations in mRCC is warranted.

Combination antiangiogenic tyrosine kinase inhibition and anti-PD1 immunotherapy in metastatic renal cell carcinoma: A retrospective analysis of safety, tolerance, and clinical outcomes.

INTRODUCTION: Two separate antiangiogenic tyrosine kinase inhibitors (TKIs) and immunotherapy (IO) combinations are FDA-approved as front-line treatment for metastatic renal cell carcinoma (mRCC). Little is known about off-protocol and post-front-line experience with combination TKI-IO approaches. METHODS: We conducted a retrospective analysis of mRCC patients who received combination TKI-IO post-first-line therapy between November 2015 and January 2019 at MD Anderson Cancer Center and Duke Cancer Institute. Chart review detailed patient characteristics, treatments, toxicity, and survival. Independent radiologists, blinded to clinical data, assessed best radiographic response using RECIST v1.1. RESULTS: We identified 48 mRCC patients for inclusion: median age 65 years, 75.0% clear cell histology, 68.8% IMDC intermediate risk, and median two prior systemic therapies. TKI-IO combinations included nivolumab-cabozantinib (N +C; 24 patients), nivolumab-pazopanib (N+P; 13), nivolumab-axitinib (6), nivolumab-lenvatinib (2), and nivolumab-ipilimumab-cabozantinib (3). The median progression-free survival was 11.6 months and the median overall survival was not reached. Response data were available in 45 patients: complete response (CR; n = 3, 6.7%), partial response (PR; 20, 44.4%), stable disease (SD; 19, 42.2%), and progressive disease (3, 6.7%). Overall response rate was 51% and disease control rate (CR+PR+SD) was 93%. Only one patient had a grade ≥3 adverse event. CONCLUSION: To our knowledge, this is the first case series reporting off-label use of combination TKI-IO for mRCC. TKI-IO combinations, particularly N+P and N+C, are well tolerated and efficacious. Although further prospective research is essential, slow disease progression on IO or TKI monotherapy may be safely controlled with addition of either TKI or IO.

Circulating Tumor Cell Chromosomal Instability and Neuroendocrine Phenotype by Immunomorphology and Poor Outcomes in Men with mCRPC Treated with Abiraterone or Enzalutamide.

PURPOSE: While the detection of AR-V7 in circulating tumor cells (CTC) is associated with resistance to abiraterone or enzalutamide in men with metastatic castration-resistant prostate cancer (mCRPC), it only accounts for a minority of this resistance. Neuroendocrine (NE) differentiation or chromosomal instability (CIN) may be additional mechanisms that mediate resistance. EXPERIMENTAL DESIGN: PROPHECY was a multicenter prospective study of men with high-risk mCRPC starting abiraterone or enzalutamide. A secondary objective was to assess Epic CTC CIN and NE phenotypes before abiraterone or enzalutamide and at progression. The proportional hazards (PH) model was used to investigate the prognostic importance of CIN and NE in predicting progression-free survival and overall survival (OS) adjusting for CTC number (CellSearch), AR-V7, prior therapy, and clinical risk score. The PH model was utilized to validate this association of NE with OS in an external dataset of patients treated similarly at Memorial Sloan Kettering Cancer Center (MSKCC; New York, NY). RESULTS: We enrolled 118 men with mCRPC starting on abiraterone or enzalutamide; 107 were evaluable on the Epic platform. Of these, 36.4% and 8.4% were CIN positive and NE positive, respectively. CIN and NE were independently associated with worse OS [HR, 2.2; 95% confidence interval (CI), 1.2-4.0 and HR 3.8; 95% CI, 1.2-12.3, respectively] when treated with abiraterone/enzalutamide. The prognostic significance of NE positivity for worse OS was confirmed in the MSKCC dataset (n = 173; HR, 5.7; 95% CI, 2.6-12.7). CONCLUSIONS: A high CIN and NE CTC phenotype is independently associated with worse survival in men with mCRPC treated with abiraterone/enzalutamide, warranting further prospective controlled predictive studies to inform treatment decisions.

The Role of Targeted Therapy in the Management of High-Risk Resected Kidney Cancer: What Have We Learned and How Will It Inform Future Adjuvant Trials.

The primary treatment for localized renal cell carcinoma (RCC) is surgical resection with curative intent. Despite this, many patients, especially those with high-risk features, will develop recurrent or metastatic disease. Antiangiogenic therapies targeting vascular endothelial growth factor have been a mainstay of treatment of advanced RCC for more than 10 years. Evidence supporting the use of these therapies in the adjuvant setting is mixed, although one clinical trial, S-TRAC, has shown improvements in disease-free survival with 1 year of adjuvant sunitinib among patients with clear cell histology and high-risk features, leading to the first US Food and Drug Administration approval of an adjuvant therapy for high-risk RCC patients. Further investigation into combination therapies with immunotherapy, neoadjuvant approaches, and patient selection will be key to determining optimal adjuvant therapy regimens to improve outcomes and increase cure rates for patients with localized RCC.

The Immunotherapy Landscape in Renal Cell Carcinoma.

The past 30 years have borne witness to a gradual evolution in the treatment landscape of advanced renal cell carcinoma (aRCC). Early immunotherapy approaches such as interferon-α and high-dose interleukin-2 (IL-2) therapy in this immunogenic tumor provided durable responses in only a minority of patients and came with toxic side effects. A growing understanding of the tumor biology elucidated pathways of tumorigenesis, which in turn revealed novel targets amenable to targeted therapies. Inhibition of angiogenesis and cell signaling emerged as cornerstones of treatment with the approval of bevacizumab and several pan-kinase and tyrosine kinase inhibitors. Though effective, their use has been limited by low rates of durable response, resistance, and side effects. The immunotherapy revolution of the past decade has led to immunotherapy-based combination regimens such as ipilimumab plus nivolumab, pembrolizumab plus axitinib, and avelumab plus axitinib, displacing single agent anti-angiogenic therapy in the first-line setting by demonstrating durable responses and improved survival over sunitinib. These immunotherapy-based combinations define first-line standard of care for aRCC today. The pipeline of second-line agents for consideration in patients who have disease progression despite immunotherapy regimens is robust but still in early stages of development.

Androgen receptor variant-driven prostate cancer II: advances in clinical investigation.

BACKGROUND: Approximately 10-30% of men with mCRPC will test positive for AR-V7 using one of two analytically and clinically validated circulating tumor cell (CTC)-based assays. These men have poor outcomes with approved AR-targeting therapies but may retain sensitivity to chemotherapy. Here, we discuss the clinical implications of testing and strategies that may benefit AR splice variant (AR-V)-positive men and discuss whether such variants are passengers or drivers of aggressive clinical behavior. METHODS: We conducted a systemic review of the literature, covering updates since our 2016 review on androgen receptor variants in mCRPC, outcomes, and existing and novel approaches to therapy. We provide an expert opinion about management strategies for AR-V7-positive men and key unanswered research questions. RESULTS: AR-V7-positive men, defined by Epic nuclear protein detection or the modified AdnaTest mRNA detection in CTCs, identify a subset of men with mCRPC that have a low probability of response to AR-targeting therapy with short progression-free and overall survival in multivariable analyses. AR-variants do not exist in isolation, but rather in the context of a complex, heterogeneous, and evolving mCRPC genome and phenotype as well as patient-specific clinical heterogeneity, and multiple mechanisms of resistance likely exist in patients regardless of AR-V7 detection. Efforts to develop broader resistance assays are needed, and effective treatment strategies beyond taxanes are needed to address the causal driver role of AR-variants and to benefit patients with AR-V-expressing prostate cancer. CONCLUSIONS: CTC AR-V7 detection using the AdnaTest mRNA or Epic nuclear protein assays represents the first analytically and prospective clinically validated liquid biopsy assays that may inform treatment decisions in men with mCRPC, particularly after failure of first-line AR-therapy. The importance of AR-variants is likely to increase with the earlier use of AR-targeting strategies in other settings, and novel interventions for these men are needed.

Androgen receptor variant-driven prostate cancer II: advances in laboratory investigations.

BACKGROUND: The androgen receptor (AR) is a key prostate cancer drug target. Suppression of AR signaling mediated by the full-length AR (AR-FL) is the therapeutic goal of all existing AR-directed therapies. AR-targeting agents impart therapeutic benefit, but lead to AR aberrations that underlie disease progression and therapeutic resistance. Among the AR aberrations specific to castration-resistant prostate cancer (CRPC), AR variants (AR-Vs) have emerged as important indicators of disease progression and therapeutic resistance. METHODS: We conducted a systemic review of the literature focusing on recent laboratory studies on AR-Vs following our last review article published in 2016. Topics ranged from measurement and detection, molecular origin, regulation, genomic function, and preclinical therapeutic targeting of AR-Vs. We provide expert opinions and perspectives on these topics. RESULTS: Transcript sequences for 22 AR-Vs have been reported in the literature. Different AR-Vs may arise through different mechanisms, and can be regulated by splicing factors and dictated by genomic rearrangements, but a low-androgen environment is a prerequisite for generation of AR-Vs. The unique transcript structures allowed development of in situ and in-solution measurement and detection methods, including mRNA and protein detection, in both tissue and blood specimens. AR-V7 remains the main measurement target and the most extensively characterized AR-V. Although AR-V7 coexists with AR-FL, genomic functions mediated by AR-V7 do not require the presence of AR-FL. The distinct cistromes and transcriptional programs directed by AR-V7 and their coregulators are consistent with genomic features of progressive disease in a low-androgen environment. Preclinical development of AR-V-directed agents currently focuses on suppression of mRNA expression and protein degradation as well as targeting of the amino-terminal domain. CONCLUSIONS: Current literature continues to support AR-Vs as biomarkers and therapeutic targets in prostate cancer. Laboratory investigations reveal both challenges and opportunities in targeting AR-Vs to overcome resistance to current AR-directed therapies.

CDK12-Mutated Prostate Cancer: Clinical Outcomes With Standard Therapies and Immune Checkpoint Blockade.

PURPOSE: Translational studies have shown that CDK12 mutations may delineate an immunoresponsive subgroup of prostate cancer, characterized by high neo-antigen burden. Given that these mutations may define a clinically distinct subgroup, we sought to describe outcomes to standard drugs and checkpoint inhibitors (CPI). PATIENTS AND METHODS: Clinical data from consecutive patients with CDK12 mutations were retrospectively collected from 7 centers. Several clinical-grade sequencing assays were used to assess CDK12 status. Descriptive statistics included PSA50 response rate (≥ 50% decline in prostate-specific antigen from baseline) and clinical/radiographic progression-free survival (PFS). RESULTS: Of 52 patients with CDK12-mutated prostate cancer, 27 (52%) had detected biallelic CDK12 alterations. At diagnosis, 44 (88%) had Gleason grade group 4-5, 52% had T3-T4, and 14 (27%) had M1 disease. Median follow-up was 8.2 years (95% CI, 5.6 to 11.1 years), and 49 (94%) developed metastatic disease. Median overall survival from metastasis was 3.9 years (95% CI, 3.2 to 8.1 years). Unconfirmed PSA50 response rates to abiraterone and enzalutamide in the first-line castration-resistant prostate cancer setting were 11 of 17 (65%) and 9 of 12 (75%), respectively. Median PFS on first-line abiraterone and enzalutamide was short, at 8.2 months (95% CI, 6.6 to 12.6 months) and 10.6 months (95% CI, 10.2 months to not reached), respectively. Nineteen patients received CPI therapy. PSA50 responses to CPI were noted in 11%, and PFS was short; however, the estimated 9-month PFS was 23%. PFS was higher in chemotherapy-näive versus chemotherapypretreated patients (median PFS: not reached v 2.1 months, P = .004). CONCLUSION: CDK12 mutations define an aggressive prostate cancer subgroup, with a high rate of metastases and short overall survival. CPI may be effective in a minority of these patients, and exploratory analysis supports using anti-programmed cell death protein 1 drugs early. Prospective studies testing CPI in this subset of patients with prostate cancer are warranted.

PD-L1 Assay Concordance in Metastatic Renal Cell Carcinoma and Metastatic Urothelial Carcinoma.

BACKGROUND: Immune checkpoint inhibitors are now standard of care for many patients with metastatic renal cell carcinoma (mRCC) and metastatic urothelial carcinoma (mUC). Given real-world limitations in programmed death-ligand 1 (PD-L1) testing, concordance studies between PD-L1 assays are needed. We undertook comparisons of Dako 28-8 and Ventana SP142 assays in mRCC and Dako 22C3 and Ventana SP263 assays in mUC. PATIENTS AND METHODS: Thirty-two patients with mRCC and 18 patients with mUC who had received immune checkpoint inhibitor therapy were identified. Formalin-fixed paraffin-embedded tumor samples for patients with mRCC were evaluated with Dako 28-8 and Ventana SP142 PD-L1 immunohistochemistry assays. For patients with mUC, formalin-fixed paraffin-embedded tumor samples were evaluated with Dako 22C3 and Ventana SP263 PD-L1 immunohistochemistry assays. RESULTS: The majority (29/32; 91%) of mRCC cases were concordant between assays. The majority (17/18; 94%) of mUC cases were also concordant between assays. CONCLUSIONS: There was strong concordance between PD-L1 assays chosen for comparison in both mRCC and mUC, with similar performance characteristics. One limitation is the small number of cases in this study; larger comparison studies are needed for this biomarker in mRCC and mUC.

Can RECIST response predict success in phase 3 trials in men with metastatic castration-resistant prostate cancer?

BACKGROUND: Intermediate endpoints are needed in early phase studies of men with metastatic castration-resistant prostate cancer (mCRPC) that can reliably predict success in phase 3 trials. Among men with measurable disease, objective response may provide information as to whether a treatment is likely to be successful. METHODS: We conducted a systematic review of systemic agents that have proceeded to phase 3 trials in men with mCRPC and examined the relationship between improvements in measurable disease response in phase 2 trials and successful phase 3 trials leading to regulatory approval. Only trials that included men with radiographically measurable disease were included. RESULTS: We examined 31 eligible mCRPC phase 3 trials between 1992 and 2017 and 29 of the preceding phase 2 trials for RECIST responses. Measurable tumor responses in phase 2 trials were higher for successful therapies in phase 3 trials in chemotherapy-naive men with mCRPC, but were less correlated with success in trials investigating docetaxel combination regimens or the post chemotherapy mCRPC setting. Many failed agents did not produce higher than expected response rates over control arms; however, several agents such as anti-angiogenic therapies or orteronel produced higher than expected responses without survival benefit. CONCLUSIONS: Objective responses in men with mCRPC may be associated with prolonged survival, but this association is mechanism dependent and inconsistent across trials or disease states. These data support considering RECIST response as a supportive but not sole endpoint in phase 2 trials to support launching phase 3 trials.