Advanced renal cell carcinoma management: the Latin American Cooperative Oncology Group (LACOG) and the Latin American Renal Cancer Group (LARCG) consensus update

PURPOSE

Renal cell carcinoma is an aggressive disease with a high mortality rate. Management has drastically changed with the new era of immunotherapy, and novel strategies are being developed; however, identifying systemic treatments is still challenging. This paper presents an update of the expert panel consensus from the Latin American Cooperative Oncology Group and the Latin American Renal Cancer Group on advanced renal cell carcinoma management in Brazil.

METHODS

A panel of 34 oncologists and experts in renal cell carcinoma discussed and voted on the best options for managing advanced disease in Brazil, including systemic treatment of early and metastatic renal cell carcinoma as well as nonclear cell tumours. The results were compared with the literature and graded according to the level of evidence.

RESULTS

Adjuvant treatments benefit patients with a high risk of recurrence after surgery, and the agents used are pembrolizumab and sunitinib, with a preference for pembrolizumab. Neoadjuvant treatment is exceptional, even in initially unresectable cases. First-line treatment is mainly based on tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs); the choice of treatment is based on the International Metastatic Database Consortium (IMCD) risk score. Patients at favourable risk receive ICIs in combination with TKIs. Patients classified as intermediate or poor risk receive ICIs, without preference for ICI + ICIs or ICI + TKIs. Data on nonclear cell renal cancer treatment are limited. Active surveillance has a place in treating favourable-risk patients. Either denosumab or zoledronic acid can be used for treating metastatic bone disease.

CONCLUSION

Immunotherapy and targeted therapy are the standards of care for advanced disease. The utilization and sequencing of these therapeutic agents hinge upon individual risk scores and responses to previous treatments. This consensus reflects a commitment to informed decision-making, drawn from professional expertise and evidence in the medical literature.

The Brazilian national prospective active surveillance (AS) cohort of patients with low-risk prostate cancer in the public health system: vigiaSUS study protocol

BACKGROUND

Prostate cancer exhibits a very diverse behaviour, with some patients dying from the disease and others never needing treatment. Active surveillance (AS) consists of periodic PSA assessment (prostate-specific antigen), DRE (digital rectal examination) and periodic prostate biopsies. According to the main guidelines, AS is the preferred strategy for low-risk patients, to avoid or delay definitive treatment. However, concerns remain regarding its applicability in certain patient subgroups, such as African American men, who were underrepresented in the main cohorts. Brazil has a very racially diverse population, with 56.1% self-reporting as brown or black. The aim of this study is to evaluate and validate the AS strategy in low-risk prostate cancer patients following an AS protocol in the Brazilian public health system.

METHODS

This is a multicentre AS prospective cohort study that will include 200 patients from all regions of Brazil in the public health system. Patients with prostate adenocarcinoma and low-risk criteria, defined as clinical staging T1-T2a, Gleason score ≤ 6, and PSA < 10 ng/ml, will be enrolled. Archival prostate cancer tissue will be centrally reviewed. Patients enrolled in the study will follow the AS strategy, which involves PSA and physical examination every 6 months as well as multiparametric MRI (mpMRI) every two years and prostate biopsy at month 12 and then every two years. The primary objective is to evaluate the reclassification rate at 12 months, and secondary objectives include determining the treatment-free survival rate, metastasis-free survival, and specific and overall survival. Exploratory objectives include the evaluation of quality of life and anxiety, the impact of PTEN loss and the economic impact of AS on the Brazilian public health system.

DISCUSSION

This is the first Brazilian prospective study of patients with low-risk prostate cancer under AS. To our knowledge, this is one of the largest AS study cohort with a majority of nonwhite patients. We believe that this study is an opportunity to better understand the outcomes of AS in populations underrepresented in studies. Based on these data, an AS national clinical guideline will be developed, which may have a beneficial impact on the quality of life of patients and on public health.

TRIAL REGISTRATION

Clinicaltrials registration is NCT05343936.

Bipolar Androgen Therapy: When Excess Fuel Extinguishes the Fire

Androgen deprivation therapy (ADT) remains the cornerstone of advanced prostate cancer treatment. However, the progression towards castration-resistant prostate cancer is inevitable, as the cancer cells reactivate androgen receptor signaling and adapt to the castrate state through autoregulation of the androgen receptor. Additionally, the upfront use of novel hormonal agents such as enzalutamide and abiraterone acetate may result in long-term toxicities and may trigger the selection of AR-independent cells through "Darwinian" treatment-induced pressure. Therefore, it is crucial to develop new strategies to overcome these challenges. Bipolar androgen therapy (BAT) is one such approach that has been devised based on studies demonstrating the paradoxical inhibitory effects of supraphysiologic testosterone on prostate cancer growth, achieved through a variety of mechanisms acting in concert. BAT involves rapidly alternating testosterone levels between supraphysiological and near-castrate levels over a period of a month, achieved through monthly intramuscular injections of testosterone plus concurrent ADT. BAT is effective and well-tolerated, improving quality of life and potentially re-sensitizing patients to previous hormonal therapies after progression. By exploring the mechanisms and clinical evidence for BAT, this review seeks to shed light on its potential as a promising new approach to prostate cancer treatment.

Abstract 6528: HPV status and epigenetic profiling of saliva from a cancer-free population

Identifying environmental factors and their relationship with epigenetic alterations is essential for understanding cancer, a leading cause of death. Currently, cancer screening and early detection development efforts are ongoing and epigenetics-based tests are one of the top choices as strategies. The understanding of how these alterations behave in cancer-free (CF) populations with well annotated data is essential. We randomly selected 601 saliva specimens from two Brazilian countrywide epidemiological studies POP-Brazil and SMESH. Extracted DNAs were sodium bisulfite converted and analyzed by Quantitative Methylation-Specific PCR (QMSP). Five genes previously reported as DNA methylation prone in cancer were selected (ITGA4, EDRNB, PAX5, p16, CCNA1). All participants were interviewed and provided sociodemographic and sexual behavior information as well as genital (gn) and oral biological samples. Variables were categorized and Fisher’s exact test was performed using SAS 9.4. Surprisingly, methylation in 3 cancer associated genes showed considerable frequencies in this CF group. DNA methylation was observed for EDNRB in 75/601 samples (12.5%), PAX5 in 55/601 (9.2%), and ITGA4 in 20/601 (3.3%). 12 samples displayed concomitant methylation on 2 of these 3 genes. p16 and CCNA1 methylation were only present in 1 sample each. Preliminary analyses suggest that specific genes methylation are observed with the presence of low (LR) and high-risk (HR) HPV types. EDNRB methylation groups with the presence of HR HPV type 16, 31, 39, 51, 58 and 59 from gn samples and LR types 6 and 42. ITGA4 methylation and HR HPV types 16 and 59 were detected in oral samples, and types 52, 56 and 68 in gn samples, as well as LR HPV types 40 and 42. In people with early onset of smoking, EDNRB and PAX5 seem to be more frequently methylated. The positivity of PAX5 was higher in participants who smoke, use alcohol and presented a positive diagnosis of syphilis and/or HIV. PAX5 methylation was more frequent in HR HPV 33, 58, 68 and 62 and LR type 6. Further analyses are ongoing. Our study shows methylation in cancer related genes in a CF population. The variables collected include some proven cancer risk factors and others still unknown, thus lead us to uncover directions to identify main cancer related players in a Brazilian population. The presence of cancer related alterations may indicate premalignant stages, exposure and lifestyle consequences, both at the same time or separately. In our pilot analysis, different types of HPV seem to correlate with epigenetic changes, this could bring attention to less studied HPV types and their role in carcinogenesis. Additional analyses of the current data and larger prospective, population-based studies, assessing the use of salivary DNA methylation in cancer-free and cancer groups of subjects are needed to explore the current findings and dissect the potential of saliva as a means of tracking cancer related changes.

Citation Format: Ana Paula Muterle Varela, Dieila Giomo De Lima, Laura Palmieri, Juliana Comerlato, Fernando Hayashi Sant’Anna, Isabel C Bandeira, Marina Bessel, Pedro Isaacsson Velho, Eliana M. Wendland, Mariana Brait. HPV status and epigenetic profiling of saliva from a cancer-free population [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6528.

Response and Outcomes to Immune Checkpoint Inhibitors in Advanced Urothelial Cancer Based on Prior Intravesical Bacillus Calmette-Guerin

BACKGROUND

Immune checkpoint inhibitors (ICI) improve overall survival (OS) in patients with locally advanced, unresectable, or metastatic urothelial carcinoma (aUC), but response rates can be modest. We compared outcomes between patients with and without prior intravesical Bacillus Calmette-Guerin (BCG), who received ICI for aUC, hypothesizing that prior intravesical BCG would be associated with worse outcomes.

PATIENTS AND METHODS

We performed a retrospective cohort study across 25 institutions in US and Europe. We compared observed response rate (ORR) using logistic regression; progression-free survival (PFS) and OS using Kaplan-Meier and Cox proportional hazards. Analyses were stratified by treatment line (first line/salvage) and included multivariable models adjusting for known prognostic factors.

RESULTS

A total of 1026 patients with aUC were identified; 614, 617, and 638 were included in ORR, OS, PFS analyses, respectively. Overall, 150 pts had history of prior intravesical BCG treatment. ORR to ICI was similar between those with and without prior intravesical BCG exposure in both first line and salvage settings (adjusted odds radios 0.55 [P= .08] and 1.65 [P= .12]). OS (adjusted hazard ratios 1.05 [P= .79] and 1.13 [P= .49]) and PFS (adjusted hazard ratios 1.12 [P= .55] and 0.87 [P= .39]) were similar between those with and without intravesical BCG exposure in first line and salvage settings.

CONCLUSION

Prior intravesical BCG was not associated with differences in response and survival in patients with aUC treated with ICI. Limitations include retrospective nature, lack of randomization, presence of selection and confounding biases. This study provides important preliminary data that prior intravesical BCG exposure may not impact ICI efficacy in aUC.

Clinical and genomic features of SPOP-mutant prostate cancer

BACKGROUND

Inactivating missense mutations in the SPOP gene, encoding speckle-type poxvirus and zinc-finger protein, are one of the most common genetic alterations in prostate cancer.

METHODS

We retrospectively identified 72 consecutive prostate cancer patients with somatic SPOP mutations, through next-generation sequencing analysis, who were treated at the Johns Hopkins Hospital. We evaluated clinical and genomic characteristics of this SPOP-mutant subset.

RESULTS

SPOP alterations were clustered in the MATH domain, with hotspot mutations involving the F133 and F102 residues. The most frequent concurrent genetic alterations were in APC (16/72 [22%]), PTEN (13/72 [18%]), and TP53 (11/72 [15%]). SPOP-mutant cancers appeared to be mutually exclusive with tumors harboring the TMPRSS2-ERG fusion, and were significantly enriched for Wnt pathway (APC, CTNNB1) mutations and de-enriched for TP53/PTEN/RB1 alterations. Patients with mtSPOP had durable responses to androgen deprivation therapy (ADT) with a median time-to-castration-resistance of 42.0 (95% confidence interval [CI], 25.7-60.8) months. However, time-to-castration-resistance was significantly shorter in SPOP-mutant patients with concurrent TP53 mutations (hazard ratio [HR] 4.53; p = 0.002), HRD pathway (ATM, BRCA1/2, and CHEK2) mutations (HR 3.19; p = 0.003), and PI3K pathway (PTEN, PIK3CA, and AKT1) alterations (HR 2.69; p = 0.004). In the castration-resistant prostate cancer setting, median progression-free survival was 8.9 (95% CI, 6.7-NR) months on abiraterone and 7.3 (95% CI, 3.2-NR) months on enzalutamide. There were no responses to PARP inhibitor treatment.

CONCLUSIONS

SPOP-mutant prostate cancers represent a unique subset with absent ERG fusions and frequent Wnt pathway alterations, with potentially greater dependency on androgen signaling and enhanced responsiveness to ADT. Outcomes are best for SPOP-altered patients without other concurrent mutations.

Detection of Early Progression with 18F-DCFPyL PET/CT in Men with Metastatic Castration-Resistant Prostate Cancer Receiving Bipolar Androgen Therapy

Bipolar androgen therapy (BAT) is an emerging treatment for metastatic castration-resistant prostate cancer (mCRPC). ¹⁸F-DCFPyL is a small-molecule PET radiotracer targeting prostate-specific membrane antigen (PSMA). We analyzed the utility of ¹⁸F-DCFPyL PET/CT in determining clinical response to BAT. Methods: Six men with mCRPC receiving BAT were imaged with ¹⁸F-DCFPyL PET/CT at baseline and after 3 mo of treatment. Progression by PSMA-targeted PET/CT was defined as the appearance of any new ¹⁸F-DCFPyL-avid lesion. Results: Three of 6 (50%) patients had progression on ¹⁸F-DCFPyL PET/CT. All 3 had stable disease or better on contemporaneous conventional imaging. Radiographic progression on CT or bone scanning was observed within 3 mo of progression on ¹⁸F-DCFPyL PET/CT. For the 3 patients who did not have progression on ¹⁸F-DCFPyL PET/CT, radiographic progression was not observed for at least 6 mo. Conclusion: New radiotracer-avid lesions on ¹⁸F-DCFPyL PET/CT in men with mCRPC undergoing BAT can indicate early progression.

Immune checkpoint inhibitors in advanced upper and lower tract urothelial carcinoma: a comparison of outcomes

OBJECTIVES

To compare clinical outcomes between patients with locally advanced (unresectable) or metastatic urothelial carcinoma (aUC) in the upper and lower urinary tract receiving immune checkpoint inhibitors (ICIs).

PATIENTS AND METHODS

We performed a retrospective cohort study collecting clinicopathological, treatment, and outcome data for patients with aUC receiving ICIs from 2013 to 2020 across 24 institutions. We compared the objective response rate (ORR), overall survival (OS), and progression-free survival (PFS) between patients with upper and lower tract UC (UTUC, LTUC). Uni- and multivariable logistic and Cox regression were used to assess the effect of UTUC on ORR, OS, and PFS. Subgroup analyses were performed stratified based on histology (pure, mixed) and line of treatment (first line, subsequent line).

RESULTS

Out of a total of 746 eligible patients, 707, 717, and 738 were included in the ORR, OS, and PFS analyses, respectively. Our results did not contradict the hypothesis that patients with UTUC and LTUC had similar ORRs (24% vs 28%; adjusted odds ratio [aOR] 0.73, 95% confidence interval [CI] 0.43-1.24), OS (median 9.8 vs 9.6 months; adjusted hazard ratio [aHR] 0.93, 95% CI 0.73-1.19), and PFS (median 4.3 vs 4.1 months; aHR 1.01, 95% CI 0.81-1.27). Patients with mixed-histology UTUC had a significantly lower ORR and shorter PFS vs mixed-histology LTUC (aOR 0.20, 95% CI 0.05-0.91 and aHR 1.66, 95% CI 1.06-2.59), respectively).

CONCLUSION

Overall, patients with UTUC and LTUC receiving ICIs have comparable treatment response and outcomes. Subgroup analyses based on histology showed that those with mixed-histology UTUC had a lower ORR and shorter PFS compared to mixed-histology LTUC. Further studies and evaluation of molecular biomarkers can help refine patient selection for immunotherapy.

A New Prognostic Model in Patients with Advanced Urothelial Carcinoma Treated with First-line Immune Checkpoint Inhibitors

BACKGROUND

While immune checkpoint inhibitors (ICIs) are approved in the first-line (1L) setting for cisplatin-unfit patients with programmed death-ligand 1 (PD-L1)-high tumors or for platinum (cisplatin/carboplatin)-unfit patients, response rates remain modest and outcomes vary with no clinically useful biomarkers (except for PD-L1).

OBJECTIVE

We aimed to develop a prognostic model for overall survival (OS) in patients receiving 1L ICIs for advanced urothelial cancer (aUC) in a multicenter cohort study.

DESIGN, SETTING, AND PARTICIPANTS

Patients treated with 1L ICIs for aUC across 24 institutions and five countries (in the USA and Europe) outside clinical trials were included in this study.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We used a stepwise, hypothesis-driven approach using clinician-selected covariates to develop a new risk score for patients receiving ICIs in the 1L setting. Demographics, clinicopathologic data, treatment patterns, and OS were collected uniformly. Univariate Cox regression was performed on 18 covariates hypothesized to be associated with OS based on published data. Variables were retained for multivariate analysis (MVA) if they correlated with OS (p < 0.2) and were included in the final model if p < 0.05 on MVA. Retained covariates were assigned points based on the beta coefficient to create a risk score. Stratified median OS and C-statistic were calculated.

RESULTS AND LIMITATIONS

Among 984 patients, 357 with a mean age of 71 yr were included in the analysis, 27% were female, 68% had pure UC, and 13% had upper tract UC. Eastern Cooperative Oncology Group performance status ≥2, albumin <3.5 g/dl, neutrophil:lymphocyte ratio >5, and liver metastases were significant prognostic factors on MVA and were included in the risk score. C index for new 1L risk score was 0.68 (95% confidence interval 0.65-0.71). Limitations include retrospective nature and lack of external validation.

CONCLUSIONS

We developed a new 1L ICI risk score for OS based on data from patients with aUC treated with ICIs in the USA and Europe outside of clinical trials. The score components highlight readily available factors related to tumor biology and treatment response. External validation is being pursued.

PATIENT SUMMARY

With multiple new treatments under development and approved for advanced urothelial carcinoma, it can be difficult to identify the best treatment sequence for each patient. The risk score may help inform treatment discussions and estimate outcomes in patients treated with first-line immune checkpoint inhibitors, while it can also impact clinical trial design and endpoints. TAKE  HOME MESSAGE: A new risk score was developed for advanced urothelial carcinoma treated with first-line immune checkpoint inhibitors. The score assigned Eastern Cooperative Oncology Group performance status ≥2, albumin <3.5 g/dl, neutrophil:lymphocyte ratio >5, and liver metastases each one point, with a higher score being associated with worse overall survival.

Genomic profiles and clinical outcomes in primary versus secondary metastatic hormone-sensitive prostate cancer

BACKGROUND

Clinical outcomes may differ among patients presenting with primary (de novo) metastatic hormone-sensitive prostate cancer (mHSPC) versus secondary (metachronous) mHSPC occurring after local therapy. It is unknown what molecular features distinguish these potentially distinct presentations.

METHODS

A single-center retrospective study of mHSPC patients classified as primary mHSPC (n = 121) or secondary mHSPC (n = 106). A targeted set of genes was analyzed: BRCA2, PTEN, RB1, TP53, SPOP, CDK12, any two out of PTEN/RB1/TP53 alterations, and homologous recombination deficiency mutations. TP53 mutations were categorized as loss-of-function (LOF) versus dominant-negative (DN). The impacts of genetic features on progression-free survival (PFS) and overall survival (OS) were assessed using univariate and multivariate Cox proportional hazards regression.

RESULTS

Median PFS was 15 and 30 months for men with primary and secondary mHSPC, respectively (hazard ratio: 0.57, 95% confidence interval: 0.41-0.78; p < .01). OS did not show a significant difference between groups. There were more men with Gleason 8-10 disease in the primary versus secondary mHSPC groups (83% vs. 68%; p < .01). In univariate and multivariate analyses, TP53 DN mutations showed a statistically significant association with OS for the entire mHSPC population. Conversely, SPOP mutations were associated with improved OS. Additionally, TP53 mutations (DN and LOF) were associated with worse OS for secondary mHSPC. A combination of PTEN/RB1/TP53 mutations was associated with worse OS and PFS for secondary mHSPC, while no genomic alteration affected outcomes for primary mHSPC.

CONCLUSIONS

TP53 DN mutations, but not all TP53 alterations, were the strongest predictor of negative outcomes in men with mHSPC, while SPOP mutations were associated with improved outcomes. In subgroup analyses, specific alterations were prognostic of outcomes in secondary, but not primary, mHSPC.

Quality of life and long-term outcomes after hospitalization for COVID-19: Protocol for a prospective cohort study (Coalition VII)

INTRODUCTION

The long-term effects caused by COVID-19 are unknown. The present study aims to assess factors associated with health-related quality of life and long-term outcomes among survivors of hospitalization for COVID-19 in Brazil.

METHODS

This is a multicenter prospective cohort study nested in five randomized clinical trials designed to assess the effects of specific COVID-19 treatments in over 50 centers in Brazil. Adult survivors of hospitalization due to proven or suspected SARS-CoV-2 infection will be followed-up for a period of 1 year by means of structured telephone interviews. The primary outcome is the 1-year utility score of health-related quality of life assessed by the EuroQol-5D3L. Secondary outcomes include all-cause mortality, major cardiovascular events, rehospitalizations, return to work or study, physical functional status assessed by the Lawton-Brody Instrumental Activities of Daily Living, dyspnea assessed by the modified Medical Research Council dyspnea scale, need for long-term ventilatory support, symptoms of anxiety and depression assessed by the Hospital Anxiety and Depression Scale, symptoms of posttraumatic stress disorder assessed by the Impact of Event Scale-Revised, and self-rated health assessed by the EuroQol-5D3L Visual Analog Scale. Generalized estimated equations will be performed to test the association between five sets of variables (1- demographic characteristics, 2- premorbid state of health, 3- characteristics of acute illness, 4- specific COVID-19 treatments received, and 5- time-updated postdischarge variables) and outcomes.

ETHICS AND DISSEMINATION

The study protocol was approved by the Research Ethics Committee of all participant institutions. The results will be disseminated through conferences and peer-reviewed journals.

New approaches to targeting the androgen receptor pathway in prostate cancer

The androgen signaling axis has been the main therapeutic target in the management of advanced prostate cancer for several decades. Over the past years, significant advances have been made in terms of a better understanding the androgen receptor (AR) pathway and mechanisms of castration resistance, along with the development of more potent AR-targeted therapies. New drugs, such as abiraterone, enzalutamide, apalutamide, and darolutamide, have been approved for castration-resistant prostate cancer and also have demonstrated an overall survival benefit in the castration-sensitive state. Despite these major advances, the majority of patients eventually present with disease progression and a rise in prostate-specific antigen, reflecting a continuous dependence of disease on the AR pathway. In this setting, a number of AR-related mechanisms of resistance have been described, and novel strategies to overcome them are an important unmet need. In this manuscript, we review the most promising strategies to target the AR pathway in prostate cancer, including bromodomain and extraterminal (BET)/bromodomain inhibitors, CREB-binding protein/p300 inhibitors, N-terminal domain inhibitors, proteolysis-targeting chimeras, and AR-targeting vaccines. Another interesting and disruptive approach to targeting the AR and potentially reversing resistance to second-generation AR antagonists is the cyclic administration of high-dose testosterone, known as bipolar androgen therapy, which is currently being explored in multiple ongoing trials.

Tumor Frameshift Mutation Proportion Predicts Response to Immunotherapy in Mismatch Repair-Deficient Prostate Cancer

Background

Genomic biomarkers that predict response to anti‐PD1 therapy in prostate cancer are needed. Frameshift mutations are predicted to generate more neoantigens than missense mutations; therefore, we hypothesized that the number or proportion of tumor frameshift mutations would correlate with response to anti‐PD1 therapy in prostate cancer.

Methods

To enrich for response to anti‐PD1 therapy, we assembled a multicenter cohort of 65 men with mismatch repair‐deficient (dMMR) prostate cancer. Patient characteristics and outcomes were determined by retrospective chart review. Clinical somatic DNA sequencing was used to determine tumor mutational burden (TMB), frameshift mutation burden, and frameshift mutation proportion (FSP), which were correlated to outcomes on anti‐PD1 treatment. We subsequently used data from a clinical trial of pembrolizumab in patients with nonprostatic dMMR cancers of various histologies as a biomarker validation cohort.

Results

Nineteen of 65 patients with dMMR metastatic castration‐resistant prostate cancer were treated with anti‐PD1 therapy. The PSA₅₀ response rate was 65%, and the median progression‐free survival (PFS) was 24 (95% confidence interval 16–54) weeks. Tumor FSP, more than overall TMB, correlated most strongly with prolonged PFS and overall survival (OS) on anti‐PD1 treatment and with density of CD8+ tumor‐infiltrating lymphocytes. High FSP similarly identified patients with longer PFS as well as OS on anti‐PD1 therapy in a validation cohort.

Conclusion

Tumor FSP correlated with prolonged efficacy of anti‐PD1 treatment among patients with dMMR cancers and may represent a new biomarker of immune checkpoint inhibitor sensitivity.

Implications for Practice

Given the modest efficacy of immune checkpoint inhibition (ICI) in unselected patients with advanced prostate cancer, biomarkers of ICI sensitivity are needed. To facilitate biomarker discovery, a cohort of patients with DNA mismatch repair‐deficient (dMMR) prostate cancer was assembled, as these patients are enriched for responses to ICI. A high response rate to anti‐PD1 therapy in these patients was observed; however, these responses were not durable in most patients. Notably, tumor frameshift mutation proportion (FSP) was identified as a novel biomarker that was associated with prolonged response to anti‐PD1 therapy in this cohort. This finding was validated in a separate cohort of patients with nonprostatic dMMR cancers of various primary histologies. This works suggests that FSP predicts response to anti‐PD1 therapy in dMMR cancers, which should be validated prospectively in larger independent cohorts.

Biomarkers of immune checkpoint inhibition sensitivity are needed. This article reports on genomic biomarkers that may predict response to anti‐PD1 therapy in prostate cancer.

The development of apalutamide for the treatment of prostate cancer

INTRODUCTION

Prostate cancer progresses, despite androgen-deprivation therapy, the backbone of its treatment. This progression is mainly related to the androgen receptor (AR)-related mechanisms of resistance, and, several AR-targeted therapies have demonstrated benefit in metastatic and nonmetastatic disease. Apalutamide is a third-generation AR-targeted therapy which competitively blocks the AR and prevents AR dimerization, nuclear internalization, thereby avoiding cancer progression. Early studies have demonstrated that apalutamide was safe and demonstrated clinical benefit. Phase II and phase III studies had confirmed preliminary results of clinical benefit with apalutamide in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) and in metastatic hormone-sensitive prostate cancer (mHSPC).

AREAS COVERED

Herein, the authors discuss the development of apalutamide, from its discovery and early studies to phase III trials. They also examine new perspectives and biomarkers that may help oncologists to make decisions in patients taking apalutamide. Studies evaluating apalutamide in other settings and in combination with other therapies are also debated.

EXPERT OPINION

Apalutamide has become a relevant therapy for patients with nmCRPC and mHSPC for its benefit in delaying metastasis in addition to its improvement of overall survival, without compromising the quality of life. Apalutamide should be considered as a standard-of-care for patients with nmCRPC and patients with mHSPC.

Association of SPOP Mutations with Outcomes in Men with De Novo Metastatic Castration-sensitive Prostate Cancer

Recently, mutations in speckle-type pox virus and zinc finger protein (SPOP) gene (mutant SPOP [mtSPOP]) have been associated with improved outcomes to abiraterone in the castration-resistant setting. We hypothesized that mtSPOP would be associated with improved outcomes to systemic therapy in men with de novo metastatic castration-sensitive prostate cancer (d-mCSPC). Retrospective data of newly diagnosed d-mCSPC patients were collected from four institutions. Eligibility criteria included standard androgen deprivation therapy without intensification, and SPOP mutational status (mtSPOP or wild-type SPOP [wtSPOP]) determination by targeted next-generation sequencing from tumor biopsies. A total of 121 men (25 mtSPOP [21%] and 96 wtSPOP [79%]) were included. After adjusting for covariates, mtSPOP was significantly associated with better median progression-free survival (35 vs 13 mo; adjusted hazard ratio [HR] 0.47; p =  0.016) and overall survival (97 vs 69 mo; adjusted HR 0.32; p =  0.027), with similar HR and p value on the univariate analysis. These findings, upon external validation, may assist with counseling and prognostication in the clinic, and inform the design of future clinical trials in this setting. PATIENT SUMMARY: : Presence of tumor mutation in speckle-type pox virus and zinc finger protein (SPOP) gene was associated with improved survival outcomes in men with de novo metastatic castration-sensitive prostate cancer receiving standard androgen deprivation therapy.

Genomic profiles and clinical outcomes to distinguish primary from secondary metastatic hormone-sensitive prostate cancer (mHSPC)

e17558

Background: Clinical outcomes may differ among pts with primary (de novo) mHSPC vs. secondary (relapsed) mHSPC occurring after previous local therapy. However, it is unknown what molecular features distinguish these potentially distinct presentations. Methods: A single-center retrospective study was performed using pts with mHSPC and available somatic genomic data. Clinicopathologic characteristics were collected, and pts were classified as primary mHSPC (n = 118) or secondary mHSPC (n = 104). A targeted set of genes suspected to influence disease severity and response to systemic therapy was analyzed: BRCA2, PTEN, RB1, TP53, SPOP, CDK12, combined PTEN/RB1/TP53 alterations (2 out of 3), and a composite of any homologous recombination deficiency (HRD) mutation. Hazard ratios for PFS and OS were compared between groups using the log-rank test. Differences in genomic features and baseline characteristics between groups were compared using Fischer exact and chi-squared tests. Results: Median PFS from initiation of first-line ADT was 16.0 mo and 28.9 mo for men with primary and secondary mHSPC, respectively (HR 0.59, 95% CI 0.43–0.83; P= 0.002). OS did not differ between groups (HR 0.92, 95% CI 0.56–1.52; P= 0.7) There were more men with Gleason 8-10 disease in the primary vs. secondary mHSPC groups (91% vs. 67%, P= < 0.01). In terms of molecular alterations, there were more PTEN and CDK12 mutations in the primary mHSPC group ( PTEN: 27% vs 19%, CDK12: 7% vs 3%), but more BRCA2 mutations in the secondary mHSPC group (5% vs 10%, respectively). In univariate analysis, PTEN mutations (HR 1.39, P= 0.08) and combined PTEN/RB1/TP53 mutations (HR 1.46, P= 0.09) predicted worse PFS; PTEN mutations (HR 1.63, P= 0.09) and combined PTEN/RB1/TP53 mutations (HR 2.38, P= 0.01) also predicted worse OS. In multivariable models adjusting for age at first metastasis and Gleason sum, only combined PTEN/RB1/TP53 mutations were predictive of worse OS (adjusted HR 2.32, 95% CI 1.14–4.71; P= 0.02). Conclusions: Compared to secondary mHSPC, primary mHSPC pts had higher Gleason scores, more frequent PTEN and CDK12 mutations, and less frequent BRCA2 mutations. In our study, such pts demonstrated worse PFS but not OS. While the strongest negative predictor of OS was the presence of combined PTEN/RB1/TP53 mutations, other contributors such as CDK12 and BRCA2 may also partially explain differences in outcomes. Thus, primary mHSPC appears to be clinically and genomically distinct from secondary mHSPC, and may require unique treatment paradigms.

CDK12-Altered Prostate Cancer: Clinical Features and Therapeutic Outcomes to Standard Systemic Therapies, Poly (ADP-Ribose) Polymerase Inhibitors, and PD-1 Inhibitors

PURPOSE

In prostate cancer, inactivating CDK12 mutations lead to gene fusion-induced neoantigens and possibly sensitivity to immunotherapy. We aimed to clinically, pathologically, and molecularly characterize CDK12-aberrant prostate cancers.

METHODS

We conducted a retrospective multicenter study to identify patients with advanced prostate cancer who harbored somatic loss-of-function CDK12 mutations. We used descriptive statistics to characterize their clinical features and therapeutic outcomes (prostate-specific antigen [PSA] responses, progression-free survival [PFS]) to various systemic therapies, including sensitivity to poly (ADP-ribose) polymerase and PD-1 inhibitors.

RESULTS

Sixty men with at least monoallelic (51.7% biallelic) CDK12 alterations were identified across nine centers. Median age at diagnosis was 60.5 years; 71.7% and 28.3% were white and nonwhite, respectively; 93.3% had Gleason grade group 4-5; 15.4% had ductal/intraductal histology; 53.3% had metastases at diagnosis; and median PSA was 24.0 ng/mL. Of those who underwent primary androgen deprivation therapy for metastatic hormone-sensitive disease (n = 59), 79.7% had a PSA response, and median PFS was 12.3 months. Of those who received first-line abiraterone and enzalutamide for metastatic castration-resistant prostate cancer (mCRPC; n = 34), 41.2% had a PSA response, and median PFS was 5.3 months. Of those who received a first taxane chemotherapy for mCRPC (n = 22), 31.8% had a PSA response, and median PFS was 3.8 months. Eleven men received a PARP inhibitor (olaparib [n = 10], rucaparib [n = 1]), and none had a PSA response (median PFS, 3.6 months). Nine men received a PD-1 inhibitor as fourth- to sixth-line systemic therapy (pembrolizumab [n = 5], nivolumab [n = 4]); 33.3% had a PSA response, and median PFS was 5.4 months.

CONCLUSION

CDK12-altered prostate cancer is an aggressive subtype with poor outcomes to hormonal and taxane therapies as well as to PARP inhibitors. A proportion of these patients may respond favorably to PD-1 inhibitors, which implicates CDK12 deficiency in immunotherapy sensitivity.

Impact of performance status on treatment outcomes: A real-world study of advanced urothelial cancer treated with immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) represent an appealing treatment for patients with advanced urothelial cancer (aUC) and a poor performance status (PS). However, the benefit of ICIs for patients with a poor PS remains unknown. It was hypothesized that a poor Eastern Cooperative Oncology Group (ECOG) PS (≥2 vs 0-1) would correlate with shorter overall survival (OS) in patients receiving ICIs.

METHODS

In this retrospective cohort study, clinicopathologic, treatment, and outcome data were collected for patients with aUC who were treated with ICIs at 18 institutions (2013-2019). The overall response rate (ORR) and OS were compared for patients with an ECOG PS of 0 to 1 and patients with an ECOG PS ≥ 2 at ICI initiation. The association between a new ICI in the last 30 and 90 days of life (DOL) and death location was also tested.

RESULTS

Of the 519 patients treated with ICIs, 395 and 384 were included in OS and ORR analyses, respectively, with 26% and 24% having a PS ≥ 2. OS was higher in those with a PS of 0 to 1 than those with a PS ≥ 2 who were treated in the first line (median, 15.2 vs 7.2 months; hazard ratio [HR], 0.62; P = .01) but not in subsequent lines (median, 9.8 vs 8.2 months; HR, 0.78; P = .27). ORRs were similar for patients with a PS of 0 to 1 and patients with a PS ≥ 2 in both lines. Of the 288 patients who died, 10% and 32% started ICIs in the last 30 and 90 DOL, respectively. ICI initiation in the last 30 DOL was associated with increased odds of death in a hospital (odds ratio, 2.89; P = .04).

CONCLUSIONS

Despite comparable ORRs, ICIs may not overcome the negative prognostic role of a poor PS, particularly in the first-line setting, and the initiation of ICIs in the last 30 DOL was associated with hospital death location.

Real-world prognostic model for overall survival (OS) in patients (pts) with advanced urothelial cancer (aUC) treated with immune checkpoint inhibitors (ICI)

447

Background: While ICI prolong OS after platinum chemotherapy in aUC, outcomes vary based on clinical confounders. We aimed to develop a prognostic model in pts receiving ICI in a non-clinical trial setting. Methods: We used a hypothesis driven approach of clinician selected covariates to develop a new prognostic model. Data source was a retrospective cohort of pts treated with ICI at 19 institutions. Demographics, clinicopathologic data, treatment patterns, and OS were collected. Univariate (UVA) Cox regression was done on 24 variables hypothesized to be associated with OS. Variables were retained for multivariate analysis (MVA) if they had statistical relationship with OS (p<0.2) and were included in the final model if p<0.05 on MVA. Each retained covariate was assigned 1 point in the final prognostic model. Stratified median OS and c-statistic were calculated. Results: 415 pts with mean age 69, 26% female, 66% ever smokers, 69% pure UC, 15% upper tract UC, 54% with prior extirpative surgery, Bellmunt risk factors 17%, 51%, 28% and 4% for 0, 1, 2, 3, respectively were included. Non-White race, ECOG PS≥1, albumin<3.5g/dL (lower limit of normal), hemoglobin<10g/dL, absolute neutrophil count (ANC)>8x106/ul (upper limit of normal), and presence of bone or liver metastases (mets) were all associated with worse OS on UVA Cox regression; albumin<3.5 g/dL, ANC>8x106/uL, presence of bone or liver mets remained significant on MVA and were included in the prognostic model. Median (m)OS by new model and Bellmunt are shown in table. C-statistic of the new model was 0.67. Conclusions: Albumin<3.5 g/dL, ANC >8x106/ul, presence of bone or liver mets were negative prognostic factors in pts with aUC treated with ICI. This has comparable features to recently reported 5-factor model using clinical trial data, including LDH (unavailable in our cohort). External validation is being pursued. The proposed model may be used for prognostication, clinical trial design, eligibility and stratification. [Table: see text]

Histologic subtype and response to immune checkpoint inhibitor (ICI) therapy in advanced urothelial cancer (aUC)

495

Background: Urinary tract cancer can be pure urothelial carcinoma (PUC) or variant UC (VUC, defined here as pure non-UC or mixed UC + non-UC); VUC often has a worse prognosis. Little is known about outcomes for patients (pts) with VUC receiving ICI. We hypothesized that VUC does not compromise ICI efficacy in pts with aUC. Methods: We performed a retrospective cohort study across 18 institutions. Demographic, clinicopathologic, treatment and outcomes data was collected for pts with aUC who received ICI. Pts were stratified to PUC vs VUC; VUC was further divided by histologic subtype, i.e. squamous, neuroendocrine (NE), etc. We compared overall response rate (ORR) using logistic regression, progression free survival (PFS) and overall survival (OS) using Kaplan-Meier and Cox proportional hazards; p<0.05 was significant. Results: 519 consecutive pts were identified; 405, 414 and 411 included in ORR, OS and PFS analyses, respectively. Demographics included mean age 69, 27% female, 66% ever smokers, 15% upper tract disease, 54% with extirpative surgery. ORR to ICI between pts with PUC and VUC was comparable (both 28%, p=0.86) without significant differences for individual subtypes vs PUC. Median OS for pts with PUC was 11.0 vs 9.9 mo for VUC (p=0.45), but only 3.7 mo for those with NE features (HR=3.01 [95% CI 1.63-5.57] vs PUC, p<0.001). Median PFS was 4.1 vs 5.2 mo for PUC vs VUC (p=0.46) and 2.8 mo for NE (HR=1.85 [95% CI 0.94-3.61] vs PUC, p=0.07). Conclusions: ORR to ICI and OS were comparable across histologic types; however, OS was shorter for tumors with NE features. VUC should not exclude pts from receiving ICI in routine practice and clinical trials.[Table: see text]

Overall survival using radium-223 (Ra223) in metastatic castrate-resistant prostate cancer (mCRPC) patients with and without DNA damage repair (DDR) defects

121

Background: Ra223 is a therapeutic option for mCRPC patients (pts) with symptomatic bone metastases. DDR-defective prostate cancers, specifically those with homologous recombination deficiency (HRD), accumulate irreparable DNA damage following genotoxic treatment. This study assessed presence or absence of DDR alterations in mCRPC pts treated with Ra223, investigating the effect on efficacy and overall survival (OS). Methods: All pts included were treated with Ra223 and had genomic results from a comprehensive next-generation sequencing panel of DDR genes that directly or indirectly led to HRD, from primary or metastatic tissue. Exclusion criteria were prior platinum-based chemotherapy or treatment with poly-ADP ribose polymerase inhibitors (PARPi). Pts were grouped by presence (DDR+) or absence (DDR-) of pathogenic somatic and/or germline aberrations in DDR genes. Primary endpoint was OS, and secondary endpoints were time to alkaline phosphatase (ALP) progression, time to next systemic therapy and biochemical responses; comparing DDR+ and DDR– groups. Results: 93 pts were included in this two-centre retrospective study. Median age was 68 years. 56% received prior chemotherapy. Baseline characteristics where comparable between DDR status subgroups. 28 (30%) pts had mutations in DDR genes, most frequently occurring in ATM (8.6%), BRCA2 (6.5%), and CDK12 (4.3%) genes. DDR+ pts showed prolonged OS (median 36.3 vs. 17.0 months; HR 2.29; 95% CI 1.21-4.32; P= 0.01). Median time to alkaline phosphatase progression was 6.9 months for DDR+ pts and 5.8 months for DDR- pts (HR 1.48; 95% CI 0.87-2.50; P =0.15), and median time to next systemic therapy was 8.9 months for DDR+ pts and 7.3 months for DDR- pts (HR 1.58; 95% CI 0.94-2.64; P =0.08). A higher proportion of DDR+ pts completed Ra223 therapy (79% vs 47%; P= 0.05). No differences in biochemical (prostate-specific antigen, ALP) responses were seen. Conclusions: Pts harboring deleterious DDR aberrations more commonly completed Ra223, and derived a greater OS benefit. These findings need prospective confirmation, but support combination of Ra223 with PARPi or ATR inhibitors in DDR-defective mCRPC pts.

Impact of somatic SPOP (Speckle-Type POZ protein) mutation (mtSPOP) on response to systemic therapy and survival outcome in men with de novo metastatic castration-sensitive prostate cancer (d-mCSPC)

329

Background: Men with metastatic castration resistant prostate cancer harboring somatic mutant SPOP (mt SPOP) have improved progression free survival (PFS) on abiraterone than those with wild-type SPOP (wt SPOP) (Boysen et al, CCR 2018; PMID: 30068710). We hypothesized that mtSPOP will be associated with improved response to systemic therapy and outcomes in mCSPC. Methods: This retrospective study included patients from 4 academic institutions. Eligibility criteria: receipt of standard androgen deprivation therapy (ADT) without intensification (chemotherapy or novel hormonal agents) for the diagnosis of d-mCSPC, no prior history or treatment for prostate cancer, and established SPOP status determined by targeted next-generation sequencing. PFS was defined per PCWG2 defined PSA or investigator assessed radiographic progression. Overall survival (OS) was calculated from date of starting ADT for d-mCSPC to date of death. Kaplan-Meier analysis and t-test were used to compare variables in these two cohorts. Results: Of 110 mtSPOP men with advanced prostate cancer identified, 37 had d-mCSPC of which 25 received ADT. Of 353 wtSPOP patients, 184 had d-mCSPC of which 97 received ADT. Baseline demographics and disease characteristic were similar (table). mtSPOP was associated with significantly improved PFS [35 vs. 14 months, HR 0.519 (95% CI 0.312-0.861), p=0.011] and OS [97 vs. 69 months, HR 0.4392 (95% CI=0.207-0.931); p=0.032] with ADT as compared to wtSPOP patients. Conclusions: Men with d-mCSPC with somatic mtSPOP have improved outcomes with ADT than those with wtSPOP. Once validated, these hypothesis generating data may aid with counselling and treatment selection, as well as patient stratification in future trials in d-mCSPC.[Table: see text]

Real-world evidence on first-line treatment for metastatic renal cell carcinoma with non-clear cell and sarcomatoid histologies: are sunitinib and pazopanib interchangeable?

Introduction

Non-clear cell renal cell carcinoma (nccRCC) and sarcomatoid renal cell carcinoma (sRCC) are underrepresented in clinical trials. Treatment approaches are frequently extrapolated from data of clear cell renal cell carcinoma, in which pazopanib is non-inferior to sunitinib. We aim to compare the effectiveness of first-line sunitinib and pazopanib for nccRCC and sRCC.

Methods

We evaluated a retrospective cohort of patients with metastatic nccRCC and sRCC treated with first-line sunitinib or pazopanib at an academic cancer centre. Overall survival (OS), progression-free survival (PFS) and response rate were measured. Kaplan–Meier and log-rank analyses were used for time-to-event data. Cox regression was used for prognostic factors.

Results

Fifty-three patients were included; 16 (30.1%) treated with sunitinib and 37 (69.9%) with pazopanib. Forty-six (86.8%) patients had nccRCC and 7 (13.2%) had sRCC. The majority had intermediate or poor International Metastatic Renal-Cell Carcinoma Database Consortium risk (93%).

Median PFS was 6.6 months with sunitinib and 4.9 months with pazopanib (HR 1.75; P = 0.078). Treatment with pazopanib was associated with inferior OS in comparison with sunitinib (median OS: 30.4 months versus 8.7 months; HR 2.71, 95% CI 1.31–5.58, P = 0.007). These results were confirmed in subgroup analysis of patients with papillary, chromophobe and MiT family translocation histologies (median OS: 38.7 months versus 14.7 months; HR 3.16, 95% CI 1.20–8.29, P = 0.019). Unclassified and sarcomatoid histologies had inferior OS (median: 6.9 and 1.1 months, respectively) regardless of the treatment used.

Conclusion

In this patient cohort, pazopanib was associated with inferior OS in comparison with sunitinib for metastatic nccRCC. Larger trials are ideally warranted to confirm these results.

A pilot study of prostate-specific membrane antigen (PSMA) dynamics in men undergoing treatment for advanced prostate cancer

BACKGROUND

Prostate-specific membrane antigen (PSMA) is a rational target for noninvasive detection of recurrent prostate cancer (PCa) and for therapy of metastatic castration-resistant prostate cancer (mCRPC) with PSMA-targeted agents. Here we conducted serial measurements of PSMA expression on circulating tumor cells (CTCs) to evaluate patterns of longitudinal PSMA dynamics over the course of multiple sequential therapies.

METHODS

A retrospective investigation of men with mCRPC undergoing evaluation at medical oncology clinics at our institution assessed the dynamics of PSMA expression in the context of different systemic treatments administered sequentially. Eligibility included patients who began systemic therapies with androgen receptor (AR)-directed agents or taxane agents for whom peripheral blood samples were tested for CTC mRNA of AR splice variant-7 (AR-V7), prostate-specific antigen (PSA), and PSMA (with >2 CTC + results) in a CLIA-accredited laboratory.

RESULTS

From August 2015 to November 2017, we identified 96 eligible men. Fifteen had greater than or equal to 2 sequential therapies and evaluable CTC samples, greater than or equal to 1 expressing PSMA (PSMA+). Among the 15 patients included in this analysis, a total of 54 PSMA status evaluations were performed in the context of 48 therapies during a median follow-up of 18 months. At baseline, PSMA signal was detected ("positive") in 11 of 15 (73.3%) patients, while for 4 of 15 (26.7%) patients PSMA signal was undetectable ("negative"). In all but two patients, the baseline collection corresponded with a change in treatment. On the second assessment, PSMA increases were detected in all 4/4 (100%) PSMA-negative patients and 8 of 11 (72.7%) PSMA-positive patients. PSMA significantly decreased in a patient treated with ¹⁷⁷ Lu-PSMA-617. Serum PSA declines were seen in 7 of 8 (88%) of the treatment periods where PSMA decreased.

CONCLUSIONS

PSMA expression in CTCs is a dynamic marker. PSMA transcript declines appear to be associated with concurrent decreases in serum PSA. Sequential CTC sampling could provide a noninvasive response assessment to systemic treatment for mCRPC.

Genomic and clinical characterization of pulmonary-only metastatic prostate cancer: A unique molecular subtype

BACKGROUND

Isolated pulmonary involvement is uncommon in metastatic hormone-sensitive prostate cancer (mHSPC). To characterize outcomes and molecular alterations of this unique patient subset, we conducted a retrospective review of patients with hormone-naïve prostate cancer presenting with lung-only metastases.

METHODS

This was a retrospective single-institution study. Medical records of 25 patients presenting with pulmonary-only metastases before receiving androgen deprivation therapy (ADT) were analyzed. Germline and/or somatic genomic results, where available (n = 16), were documented. Tumor tissue was analyzed using clinical-grade next-generation DNA sequencing assays. Clinical endpoints included complete prostate-specific antigen (PSA) response to ADT (<0.1 ng/mL), median overall survival (OS) from time of ADT initiation, median PSA progression-free survival (PSA-PFS), and failure-free survival (FFS) at 4 years.

RESULTS

Baseline characteristics were notable for 48% of men (12 of 25) having first or second-degree relatives with prostate cancer, compared with 20% expected. Complete PSA responses to ADT were noted in 52% of men, with a median PSA-PFS of 66 months, a 4-year FFS rate of 72%, and a median OS that was not reached after 190 months. In evaluable patients, molecular drivers were enriched for mismatch repair mutations (4 of 16, 25%) and homologous-recombination deficiency mutations (4 of 16, 25%). These results are limited by the small sample size and retrospective nature of this analysis.

CONCLUSIONS

This exploratory study represents one of the largest cohorts of lung-only mHSPC patients to-date. The prevalence of actionable DNA-repair gene alterations was higher than anticipated (any DNA-repair mutation: 8 of 16, 50%). Compared to historical data, these patients appear to have exceptional and durable responses to first-line ADT. This study suggests that pulmonary-tropic mHSPC biology may be fundamentally different from nonpulmonary mHSPC.

Molecular Characterization and Clinical Outcomes of Primary Gleason Pattern 5 Prostate Cancer After Radical Prostatectomy

PURPOSE

Very high-risk prostate cancer (PC) is associated with poor response to local and systemic treatments; however, few cases have been molecularly profiled. We studied clinical outcomes and molecular profiles of patients with clinically localized primary Gleason pattern 5 PC.

PATIENTS AND METHODS

Clinicopathologic features, targeted somatic and germline sequencing, and PTEN, TP53, and ERG status by immunohistochemistry were assessed in patients undergoing surgery from 2005 to 2015; 60 consecutive patients were identified with Gleason score 5 + 4 = 9 or 5 + 5 = 10 PC after radical prostatectomy with available tissue and clinical follow-up. Clinicopathologic and genomic parameters were correlated with biochemical relapse, metastasis-free survival, time to castration resistance, and overall survival using Cox proportional hazards models.

RESULTS

Of patients with somatic sequencing data and clinical follow-up, 34% had DNA repair gene mutations, including 22% (11 of 49) with homologous recombination and 12% (six of 49) with mismatch repair gene alterations. Homologous recombination mutations were germline in 82% (nine of 11) of patients. In addition, 33% (16 of 49) had TP53 mutation, and 51% (29 of 57) had PTEN loss. Overall, 43% developed metastasis, with a time to castration resistance of 12 months. On multivariable analysis of clinicopathologic variables, only ductal/intraductal histology (hazard ratio, 4.43; 95% CI, 1.76 to 11.15; P = .002) and seminal vesicle invasion (hazard ratio, 5.14; 95% CI, 1.83 to 14.47; P = .002) were associated with metastasis. Among genomic alterations, only TP53 mutation and PTEN loss were associated with metastasis on univariable analysis, and neither remained significant in multivariable analyses. These data are retrospective and hypothesis generating.

CONCLUSION

Potentially actionable homologous recombination and mismatch repair alterations are observed in a significant proportion of patients with very high-risk PC at the time of radical prostatectomy. These findings could inform the design of prospective trials in this patient population.

Wnt-pathway Activating Mutations Are Associated with Resistance to First-line Abiraterone and Enzalutamide in Castration-resistant Prostate Cancer

BACKGROUND

Wnt signaling is a cellular pathway involved in embryogenesis, development, and neoplasia. Wnt-pathway activation may accelerate prostate cancer androgen-independent growth and mediate antiandrogen resistance. Since 10-20% of advanced prostate cancers harbor Wnt-activating mutations, we aimed to characterize the clinical features and response to novel antiandrogens in such patients.

OBJECTIVE

To determine whether men with metastatic castration-resistant prostate cancer (mCRPC) who harbor Wnt-pathway mutations have poorer responses to first-line novel hormonal therapies: abiraterone/enzalutamide.

DESIGN, SETTING, AND PARTICIPANTS

Patients with mCRPC who received first-line abiraterone or enzalutamide were retrospectively evaluated. Using tumor DNA analyses, we queried for activating mutations in CTNNB1 or inactivating mutations in APC or RNF43, all of which are predicted to stimulate Wnt signaling. Presence or absence of at least one Wnt-activating alteration was correlated with clinical-pathologic characteristics and treatment outcomes.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Time to prostate-specific antigen (PSA) progression, overall survival (OS), and PSA response were measured. Cox regression models were used to test associations between Wnt status and clinical-pathologic outcomes; Kaplan-Meier and log-rank analyses were used to compare time-to-event endpoints.

RESULTS AND LIMITATIONS

Of 137 patients evaluated, 11% (n=15) had tumor DNA analysis showing at least one Wnt-stimulating alteration. Patients with Wnt-activating mutations had numerically fewer T3/T4 tumors than Wnt wild-type patients (31% vs 51%), but were otherwise generally balanced. Median time to PSA progression on first-line abiraterone/enzalutamide was shorter in Wnt-activated patients (6.5 vs 9.6mo, hazard ratio [HR] 2.34, p=0.003), as was OS (23.6 vs 27.7mo, HR 2.28, p=0.01). PSA responses were numerically worse in Wnt-activated patients (53% vs 75%, p=0.12). Presence of Wnt-activating alterations (adjusted HR [aHR] 2.33, p=0.007) and use of previous chemotherapy (aHR 1.83, p=0.004) were both independently associated with increased hazard of progression.

CONCLUSIONS

Patients with somatic Wnt-pathway activating mutations have worse outcomes to first-line abiraterone/enzalutamide than Wnt wild-type patients. Our data suggest that additional genomically informed therapies are needed for this relevant subset of mCRPC patients.

PATIENT SUMMARY

In this report, we retrospectively examined outcomes of metastatic prostate cancer patients with or without Wnt-pathway mutations who received abiraterone or enzalutamide for the first time, in order to examine whether these mutations affect the prognosis. Our study suggested that patients who have Wnt-pathway activating mutations derived less benefit from abiraterone and enzalutamide when compared to patients without these mutations. We conclude that Wnt-pathway mutations might decrease the effectiveness of abiraterone and enzalutamide, and we propose that the Wnt pathway might be a good therapeutic target for these patients, in order to potentially reverse or prolong resistance to abiraterone and enzalutamide in men with Wnt mutations.

Treatment sequencing of anti-PD-1/PD-L1 and carboplatin (carbo)-based chemotherapy (chemo) in cisplatin-ineligible patients (pts) with metastatic urothelial cancer (mUC)

4541

Background: Anti-PD-1/PD-L1 agents and carbo-based chemo are therapy options in 1st-line (1L) setting for cisplatin-ineligible pts with mUC. However, optimal sequencing is unclear. Methods: We conducted a multicenter retrospective analysis of cisplatin-ineligible pts with mUC treated with 1L PD-1/PD-L1 monotherapy followed by carbo-based chemo (IO→Cb) or the reverse order (Cb→IO) without intervening systemic therapy. Perioperative cisplatin-based chemo was allowed if completed > 1 year from 1L mUC therapy initiation. To assess association between overall survival (OS) and therapy sequence, a multivariate analysis (MVA) was performed from initiation of 2L therapy, adjusted for treatment sequence, time interval between initiation of 1L and 2L therapies, Hb ( < 10 vs ≥10 g/dl), ECOG PS (0-1 vs 2-3), and metastatic site (LN/soft tissue only vs non-liver vs liver). Results: 146 pts (IO→Cb n = 43, Cb→IO n = 103) were evaluable with median age 72, 76% men, 78% ECOG PS 0-1, 17.8% with liver metastasis. Baseline factors were balanced except for higher proportion of men in IO→Cb group (91% vs 70%, p = 0.01). Median time interval between initiation of 1L and 2L therapy for IO→Cb and Cb→IO were 15.6mo (4.8-78.1) and 23.0mo (2.1-103.3), respectively. Response rates are summarized (Table). On MVA, treatment sequence was not associated with OS (HR 1.05, p = 0.85). Site of metastasis was the only factor significantly associated with OS (p = 0.002). Conclusions: In our retrospective analysis of cisplatin-ineligible pts with mUC regardless of PD-L1 expression, anti-PD-1/PD-L1 followed by carbo-based chemo or the reverse sequence appeared to confer comparable OS. The observed response rates and time interval between initiation of 1L and 2L therapy are likely contributed by pt selection, where all pts received 2L. Further investigation of the ‘PD-L1 high’ population is warranted, given higher response rates with anti-PD-1/PD-L1 vs ‘PD-L1 low’ population. Ongoing phase III trials will help inform optimal sequencing. [Table: see text]

Outcomes of patients (pts) with metastatic urothelial cancer (mUC) and poor performance status (PS) receiving anti-PD(L)1 agents

4525

Background: Anti-PD(L)1 immune checkpoint inhibitors (ICI) prolong overall survival (OS) after platinum chemotherapy in mUC. However, clinical outcomes in pts with poor PS at time of ICI initiation are unknown. We hypothesized that ICI initiation in pts with ECOG PS 2-3 would be associated with worse outcomes vs. pts with ECOG PS < 2, and impact death location. Methods: A retrospective cohort study in 8 institutions identified pts with mUC who received ICI. Demographic, clinicopathologic, treatment (tx) patterns, tx response, and outcomes were collected. Primary endpoint: overall response rate (ORR). Secondary endpoints: median (m) OS in pts receiving ICI as 1st and 2nd line (1L, 2L); odds of dying in hospital (vs elsewhere) for pts receiving ICI (vs no tx) within 30 days of death; and estimated drug cost for pts with ICI within 30 days of death based on average wholesale price. Unadjusted logistic regression was used to assess association between ORR and ECOG PS (2-3 vs < 2) and wald test was used to compare mOS between ECOG PS (2-3 vs < 2). Results: 194 consecutive pts (30% women, 41% never smokers, median age at diagnosis 69) treated with ICI for mUC were identified. Median number of total tx lines was 2; all pts received ≥1 ICI line (6 pts received 2 ICI lines); 97, 79, 17 and 7 pts received ICI in 1L, 2L, 3L and 4L, respectively; 26% pts with ICI in 1L and 2L had ECOG PS 2-3. ORR and mOS are shown in table. Among 106 pts who died, 96 had available death location; of those, 8% received ICI within 30 days of death. Starting ICI within 30 days of death (vs no tx) was associated with higher odds of hospital death (OR 6.05, 95%CI 1.3-27.6). Estimated average ICI cost/pt within 30 days of death was $1400.58. Conclusions: Pts with ECOG PS 2-3 at time of ICI initiation had similar ORR vs ECOG PS < 2 but worse mOS. ICI initiation within 30 days from death was associated with higher likelihood of hospital death. ICI may not circumvent the negative prognostic role of poor PS, so biomarker-based pt selection is critical. Limitations include lack of adjustment for selection bias and other confounders at time of ICI initiation; data validation is ongoing. [Table: see text]

WNT activating pathway mutations confer resistance to first-line antiandrogen therapy in castration-resistant prostate cancer (CRPC)

5068

Background: Wnt signaling is a cellular pathway responsible for embryogenesis and neoplasm. When activated, in about 10-20% of mCRPC, the WNT signaling pathway may cause androgen-independent growth and consequently antiandrogen resistance. To further characterize the clinical features and biology of this subtype of mCRPC, we studied mutations in genes of this pathway, including APC, CTNNB1, RNF43, ZNRF3 and RSPO2, in patients who received treatment at Johns Hopkins Hospital (JHH). Methods: Patients with CRPC who received first-line antiandrogen (abiraterone or enzalutamide) therapy for CRPC at JHH were retrospectively studied. Pathological staging, extension of primary disease, tumor somatic genomic data by Next Generation Sequencing (NGS) were correlated with clinical outcomes such as time to PSA progression, PSA response and overall survival (OS). Cox regression was used to test associations between variables and clinical outcomes and Kaplan-Meier method was used for time-to-event data. Results: Of 137 pts who received first-line antiandrogen therapy for CRPC, 10.9% (15 pts) had NGS with at least one activating WNT pathway alteration, including mutations in APC (6 pts), CTNNB1 (8 pts) and RNF43 (3 pts). Patients with WNT mutations had fewer T3/T4 tumors (30.8% vs. 51.4%, p = 0.24), but were balanced in other aspects. The median time to PSA progression in WNT activated patients was 6.5 months vs. 9.6 months in WNT negative patients (HR 2.3, 95% CI 1.3 - 4.1, p = 0.003). The presence of WNT mutations (HR 2.3, 95% CI 1.2 - 4.3, p = 0.007) and previous chemotherapy (HR 1.8, 95% CI 1.2 – 2.7, p = 0.003) were independently associated with shorter time to PSA progression. PSA50 response was numerically worse in WNT activated patients (53% vs 75%, p = 0.12). The OS in patients with WNT mutations was 23.6 months vs 27.7 months in patients without WNT mutations (HR 2.2, 95% CI 1.1 - 4.5, p = 0.01). Conclusions: Patients with WNT pathway mutations may have worse outcomes to first-line abi/enza compared to patients without these aberrations. Time to PSA progression and OS were inferior in WNT activated population. Our data reinforce the necessity to develop effective WNT pathway inhibitors to test in clinical trials for WNT activated patients.

Clinical outcomes and genomic analysis in patients with very high-risk clinically localized prostate cancer treated by radical prostatectomy

5067

Background: Very high risk prostate cancer is associated with poor response to local and systemic treatments, however few cases have been molecularly profiled. We studied patients with primary Gleason pattern 5 disease (PG5; Gleason scores 5+5 or 5+4) after undergoing radical prostatectomy (RP). Methods: Consecutive PG5 cases were retrospectively studied. Clinical-pathologic features, tumor somatic sequencing (UW Oncoplex), germline sequencing and PTEN, TP53 and ERG status by immunohistochemistry were correlated with biochemical relapse (BCR), metastasis-free survival (MFS), time to castration-resistance (TCR) and overall survival (OS). Kaplan–Meier curves were used in time-to-event data. Univariate and multivariable (MVA) Cox proportional-hazards models (95% confidence intervals (CI Clinical-pathological variables were selected for the multivariate analysis using stepwise method and were used to adjust the effect of each mutation. Results: Of 60 patients with available tissue and follow-up, 90% had non-organ confined disease, 58% had seminal vesicle invasion (SVI), 27% had lymph node involvement, and 15% had ductal or intraductal histologic features. Overall, 43% developed metastasis with a TCR of 12 months. On multivariable analysis of clinical-pathologic variables, only ductal/intraductal histology (HR = 4.43; 95% CI: 1.76-11.15; p = 0.002) and SVI (HR = 5.14; 95% CI: 1.83-14.47 p = 0.002) were associated with metastasis. Of patients with somatic sequencing data, 22% (11/49) had homologous recombination (HR) and 12% (6/49) had mismatch repair (MMR) gene alterations. In addition, 33% (16/49) had TP53 mutation and 51% (29/57) had PTEN loss. Only TP53 mutation and PTEN loss were associated with metastasis on univariable analysis and no genomic alterations remained significant in multivariable analyses. Conclusions: Patients with PG5 have poor outcomes and more than one third have mutations in DNA repair genes. The unusually high incidence of actionable HR and MMR alterations provides the rationale for the design of adjuvant clinical trials in this population. [Table: see text]

Genomic analysis and clinical outcomes of Primary Gleason Pattern 5 (PG5) prostate cancer (PCa) treated with radical prostatectomy (RP)

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Background: PG5 (5+5 and 5+4) PCa is historically associated with poor clinical outcomes such as progression to metastatic disease, poor response to androgen deprivation therapy (ADT) and short survival. To characterize the clinical features and biology of this aggressive type of PCa, we studied patients with PG5 who underwent a RP. Methods: Patients with surgical PG5 who underwent RP for localized PCa at Johns Hopkins Hospital were retrospectively studied. Pathological staging, tumor genomic data by Next Generation Sequencing (NGS), and PTEN and TP53 by IHC were correlated with clinical outcomes, such as biochemical relapse (BCR), metastasis-free survival (MFS), time to castration-resistance (TCR) and overall survival (OS). Fisher’s test and Kaplan-Meier were used for statistical analysis. Results: 60 pts, 90% pT3-4, 26% pN1, 46% R+, 90% seminal vesicle invasion (SVI) had a median follow up of 9 years. Overall median survival estimates: BCR: 17.4 months (m), MFS:86.4m and OS:111m. 26 patients developed metastasis (bone 77%, visceral 31%) with a median time to metastasis of 21.8m and TCR of 12m. On multivariate analysis, ductal/intraductal histology (HR 4.5, p<0.01) and SVI (HR 4.4, p<0.01) were associated with poor prognosis. Of 49 pts with NGS, 22% had Homologous recombination (HR) and 12% mismatch repair (MMR) alterations. In addition, 32% had TP53 mutation and 51% PTEN loss. Genomic event frequencies and outcomes are in Table. Conclusions: Patients with PG5 have adverse pathological features, short BCR, MFS and resistance to ADT, but outcomes are variable, suggesting heterogeneity. TP53 mutations and PTEN loss are associated with poor outcomes in univariate analysis, while ductal/intraductal and SVI are associated with poor outcomes in multivariate analysis. Although genomic data were not independently associated with outcomes, the high incidence of HR and MMR alterations provides the rationale for the design of adjuvant clinical trials. [Table: see text]

Genomic characterization of pulmonary-metastatic prostate cancer: A unique molecular subtype

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Background: Metastatic prostate cancer (mPC) rarely spreads to the lungs and lung-only metastatic disease has not been clearly defined. This study investigated the clinical and molecular features of lung-only mPC. Methods: This is a retrospective single-institution study. Medical records of 40 metastatic prostate patients with lung-only (N=25) or lung-predominant (N=15) disease were analyzed. Germline and/or somatic DNA sequencing results, when available, were recorded. Results: 25 lung-only mPC patients were identified, of which 14 underwent germline/somatic DNA analysis. Nine (64%) had a driver mutation in either: the WNT pathway (29%), PI3K/PTEN pathway (21%), homologous recombination DNA repair (HRD) (36%) or mismatch repair (MMR) (29%). 15 lung-predominant mPC patients were also analyzed, of which 10 underwent genomic analysis. Seven (70%) had a driver mutation in either: WNT (10%), PI3K/PTEN (40%), HRD (40%), or MMR (21%). Representative driver mutations for both cohorts summarized in Table. In comparison, in our genomic database, 52.1% had a driver mutation (in WNT 15%, PI3K/PTEN 33%, HRD 22% or MMR 4%). The lung-only and lung-predominant cohorts did not differ by age (p=0.41), race, PSA (p=0.16), Gleason sum (p=0.77), intraductal/ductal histology (p=0.71), lymphovascular invasion (p=0.64), perineural invasion (p=0.73), or having relatives with cancer (p=0.22). Our results are limited by the small sample size and retrospective nature of the analysis. Conclusions: In this exploratory study, the overall prevalence of DNA repair gene alterations was higher than anticipated (35%), suggesting a potential enrichment (esp. in MMR mutations) in men with lung-only or lung-predominant mPC. This finding may have important therapeutic implications. These results require prospective validation of the hypothesis that pulmonary-tropic mPC biology may be fundamentally different from non-pulmonary mPC, and that these patients may benefit from PARP inhibitor or anti–PD-1 treatments. Clinical outcomes data will also be presented. [Table: see text]

Clinical Features and Therapeutic Outcomes in Men with Advanced Prostate Cancer and DNA Mismatch Repair Gene Mutations

Mismatch repair (MMR) gene mutations are rare in prostate cancer, and their histological and clinical characteristics are largely unknown. We conducted a retrospective study to explore disease characteristics and treatment outcomes of men with metastatic prostate cancer harboring germline and/or somatic MMR mutations detected using clinical-grade genomic assays. Thirteen patients with a deleterious MMR gene mutation were identified. Median age was 64 yr, 75% had grade group 5 (Gleason sum 9 or 10), 23% had intraductal histology, 46% had metastatic disease at initial diagnosis, and 31% had visceral metastases. Most patients (46%) had MSH6 mutations, 73% demonstrated microsatellite instability, and median tumor mutational load was 18/Mb (range, 3-165 mutations/Mb). Surprisingly, responses to standard hormonal therapies were very durable (median progression-free survival [PFS] of 67 mo to initial androgen deprivation and median PFS of 26 mo to abiraterone/enzalutamide). Two of four men receiving PD-1 inhibitors achieved a ≥50% prostate-specific antigen response at 12 wk, with a median PFS duration in these four men of 9 mo. Despite aggressive clinical and pathological features, patients with MMR-mutated advanced prostate cancer appear to have particular sensitivity to hormonal therapies, as well as anecdotal responses to PD-1 inhibitors. Certain histological features (grade group 5, intraductal carcinoma) should prompt evaluation for MMR deficiency. These data are only hypothesis generating. PATIENT SUMMARY: Prostate cancers with mismatch repair gene mutations have aggressive clinical and pathological features; however, these are very sensitive to standard and novel hormonal therapies, and also demonstrate anecdotal sensitivity to PD-1 inhibitors such as pembrolizumab.

Efficacy of Radium-223 in Bone-metastatic Castration-resistant Prostate Cancer with and Without Homologous Repair Gene Defects

BACKGROUND

Pathogenic mutations in genes mediating homologous recombination (HR) DNA repair are present in 20-30% of men with metastatic castrate-resistant prostate cancer (mCRPC). Radium-223 is a bone-seeking α-emitter that induces double-strand DNA breaks, thereby killing cancer cells in the bone microenvironment.

OBJECTIVE

To evaluate the potential impact of germline or somatic HR-deficiency (HRD) mutations on radium-223 efficacy in mCRPC with bone metastasis.

DESIGN, SETTING, AND PARTICIPANTS

This is a retrospective single-institution study. Medical records of 190 mCRPC patients for whom germline and/or somatic DNA sequencing data were available were reviewed. Of these patients, 28 had received standard-of-care radium-223 at Johns Hopkins between February 2013 and February 2018.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Alkaline phosphatase (ALP) responses and time-to-ALP-progression were the coprimary endpoints. Prostate-specific antigen (PSA) responses, overall survival (OS), and time to next systemic therapy were also evaluated.

RESULTS AND LIMITATIONS

Of the 28 patients included, 10 men (35.7%) had a germline/somatic HRD mutation (three in BRCA2, and one each in ATM, ATR, CHEK2, FANCG, FANCI, FANCL, and PALB2) and 18 (64.3%) did not. Men with HRD mutations (HRD+) had numerically lower ages (66 vs 73yr, p=0.25), more soft-tissue metastases (50% vs 38%, p=0.43), and higher baseline ALP levels (130 vs 108 U/l, p=0.84). Compared with HRD(-) men, HRD(+) patients showed greater ALP responses (80% vs 39%, p=0.04), longer time to ALP progression (median10.4 vs 5.8mo, hazard ratio [HR] 6.4, p=0.005), and a trend toward longer OS (median 36.9 vs 19.0mo, HR 3.3, p=0.11). PSA responses (0% vs 0%, p>0.99) and time to next systemic therapy (HR 1.5, p=0.39) were similar between the two groups. Results are limited by the retrospective nature of the analysis and the small sample size.

CONCLUSIONS

In this exploratory study, bone-metastatic CRPC patients with inactivating HRD mutations demonstrated significantly improved ALP responses and time to ALP progression. These results should motivate prospective validation of the "synthetic lethality" hypothesis between HRD mutations and radium-223 activity.

PATIENT SUMMARY

In this report, we retrospectively examined outcomes to metastatic prostate cancer in patients with and without DNA repair mutations who received radium-223, a therapy that kills cancer cells by causing direct DNA damage. Our study suggested that patients who have inherited or acquired DNA repair gene mutations derived greater benefit from radium-223 when compared with patients without these mutations. We concluded that radium-223 might have an important role in this setting; however, prospective studies are needed to confirm whether DNA repair mutations truly make radium-223 work better or not.

Analysis of Efficacy and Toxicity Profile of First-Line Sunitinib or Pazopanib in Metastatic Clear Cell Renal Cell Carcinoma in the Brazilian Population

Purpose

Sunitinib and pazopanib are multitargeted tyrosine kinase inhibitors (TKIs) that act against vascular endothelial growth factor receptors and are standard first-line treatment options for metastatic clear cell renal cell carcinoma (ccRCC). The Brazilian public health system diverges from the randomized clinical trials in the availability of first and subsequent lines of treatment and in clinical and demographic characteristics of patients. Therefore, it is essential to describe the history of advanced ccRCC during and after TKI treatment in this population.

Methods

We performed a retrospective analysis of patients with advanced ccRCC treated with a first-line TKI (either sunitinib or pazopanib) between February 2009 and March 2017 in a single academic Brazilian cancer center (Instituto do Câncer do Estado de São Paulo).

Results

Of the 222 patients, 109 were treated with sunitinib and 113 with pazopanib. The median duration of treatment and overall survival (OS) were 6.4 and 15.2 months for sunitinib and 6.7 and 14.2 months for pazopanib, respectively. Discontinuation of treatment occurred secondarily to progressive disease or death in 64.2% of patients using sunitinib and in 54.8% of patients using pazopanib. Adverse events were responsible for discontinuation of treatment in 28.4% of patients in the sunitinib group and in 22.1% in the pazopanib group. According to Memorial Sloan-Kettering Cancer Center risk categories, the OS was 32.9 months, 15.9 months, and 8.1 months for low risk, intermediate risk, and poor risk, respectively (hazard ratio, 1.72; 95% CI, 1.13 to 2.26; P < .001).

Conclusion

The use of TKI inhibitors as first-line treatment of metastatic RCC is effective and feasible in the Brazilian public health. However, the median OS of our population is considerably lower compared with the prospective trials that evaluated the same drugs.

PD-1/PD-L1 pathway inhibitors in advanced prostate cancer

INTRODUCTION

Pharmacological inhibition of immune checkpoint receptors or their ligands represents a transformative breakthrough in the management of multiple cancers. However, immune checkpoint inhibitors have yet to be FDA-approved for the management of metastatic prostate cancer (PCa), the commonest non-cutaneous malignancy in men. Areas covered: We review our current understanding of the PD-1/PD-L1 pathway in cancer, the use of anti-PD-1/PD-L1 therapeutics in PCa, and potential subgroups of PCa patients who may derive the greatest benefit from these agents (such as men with tumors that have expression of PD-L1 and/or high mutational load). We also review the prior and current clinical trials evaluating the blockade of PD-1/PD-L1 in PCa, highlighting some of the key ongoing studies of greatest relevance to the field. Expert commentary: Clinical trials investigating PD-1/PD-L1 inhibitors should be encouraged in patients with PCa. While it is unlikely that immune checkpoint monotherapies will produce long-lasting responses in a substantial proportion of patients, there is early evidence of activity in some patient subsets. These subgroups may include those with high PD-L1 expression, those with hypermutated or microsatellite-unstable tumors, and those enriched for germline and/or somatic DNA-repair gene mutations (e.g. intraductal/ductal histology, primary Gleason pattern 5, and perhaps AR-V7-positive tumors).

Intraductal/ductal histology and lymphovascular invasion are associated with germline DNA-repair gene mutations in prostate cancer

BACKGROUND

Germline mutations in genes mediating DNA repair are common in men with recurrent and advanced prostate cancer, and their presence may alter prognosis and management. We aimed to define pathological and clinical characteristics associated with germline DNA-repair gene mutations, to facilitate selection of patients for germline testing.

METHODS

We retrospectively evaluated 150 unselected patients with recurrent or metastatic prostate cancer who were offered germline genetic testing by a single oncologist using a clinical-grade assay (Color Genomics). This platform utilizes next-generation sequencing from saliva to interrogate 30 cancer-susceptibility genes. Presence or absence of a deleterious germline mutation was correlated with histological and clinical characteristics, and with family history of cancer. All patients with DNA-sequence alterations (pathogenic or variants) were offered genetic counseling.

RESULTS

Between July 2016 and July 2017, 150 consecutive patients underwent germline testing; pathogenic mutations were identified in 21 men (14%). Among those with germline mutations, 9 (43%) were in BRCA2, 3 (14%) were in ATM, 3 (14%) were in CHEK2, and 2 (9%) were in BRCA1. While there were no associations between germline mutations and age, tumor stage, Gleason sum or family history; mutation-positive patients had lower median PSA levels at diagnosis (5.5 vs 8.6 ng/mL, P = 0.01) and unique pathologic features. Namely, men with germline mutations were more likely to harbor intraductal/ductal histology (48% vs 12%, P < 0.01) and lymphovascular invasion (52% vs 14%, P < 0.01). Finally, 44% of patients with a positive germline test would not have been offered genetic screening according to current National Comprehensive Cancer Network (NCCN) guidelines.

CONCLUSIONS

Presence of intraductal/ductal histology and lymphovascular invasion appear to be associated with pathogenic germline DNA-repair gene mutations in men with prostate cancer, and identification of these features may help to select patients for germline testing. NCCN guidelines may be inadequate in predicting which prostate cancer patients should undergo genetic screening.