Prognostic Factors for Survival in Patients Undergoing Surveillance After Cytoreductive Nephrectomy.

PURPOSE: The clinical course of patients being placed on surveillance in a cohort of systemic therapy-naïve patients who undergo cytoreductive nephrectomy is not well documented. Thus, we evaluated the clinical course of patients placed on surveillance following cytoreductive nephrectomy and identified predictors of survival. MATERIALS AND METHODS: In this large single-institution study, we retrospectively analyzed metastatic renal cell carcinoma patients who underwent cytoreductive nephrectomy followed by surveillance. Predictors of survival were evaluated using the Kaplan-Meier method with a log-rank test. Patients were risk stratified based on IMDC (International mRCC Database Consortium) and number of metastatic sites (Rini score), with IMDC score ≤1 and ≤2 metastatic organ sites considered favorable risk. Primary end point was systemic therapy-free survival. Secondary end points included intervention-free survival, cancer-specific survival, and overall survival. RESULTS: Median systemic therapy-free survival was 23.6 months (95% CI: 15.1-40.6), intervention-free survival was 11.8 months (95% CI: 8.0-18.4), cancer-specific survival was 54.2 months (95% CI: 46.2-71.4), and overall survival 52.4 months (95% CI: 40.3-66.8). Favorable-risk patients compared to unfavorable-risk patients had longer systemic therapy-free survival (50.6 vs 11.1 months, P < .01), survival (25.2 vs 7.3, P < .01), and cancer-specific survival (71.4 vs 46.2 months, P = .02). CONCLUSIONS: Using risk stratification based on IMDC and number of metastatic sites, surveillance in favorable-risk patients can be utilized for a period without the initiation of systemic therapy. This approach can delay patients' exposure to the side effects of systemic therapy.

Surgical Complications Requiring Intervention in Open versus Minimally Invasive Radical Prostatectomy.

INTRODUCTION: Injuries to surrounding structures during radical prostatectomy (RP) are rare but serious complications. However, it remains unknown if injuries to intestines, rectum, or vascular structures occur at different rates depending on the surgical approach. METHODS: We compared the frequency of these outcomes in open RP (ORP) and minimally invasive RP (MIS-RP) using the national American College of Surgeons National Surgical Quality Improvement Program database (2012-2017). Along with important metrics of clinical and surgical outcomes, patients were identified as undergoing surgical repair of small or large bowel, vascular structures, or hernias based on Current Procedural Terminology codes. RESULTS: In our propensity matched analysis, a total of 13,044 patients were captured. Bowel injury occurred more frequently in ORP than in MIS-RP (0.89 vs. 0.26%, p < 0.01). By intestinal segment, rectal and large bowel injuries were more common in ORP than MIS-RP (0.41 vs. 0.11% and 0.31 vs. 0.05%, both p < 0.01). However, there was no statistically significant difference between the groups for small bowel injury (0.17 vs. 0.11%, p = 0.39). Vascular injury was more common in MIS-RP (0.18 vs. 0.08%, p = 0.08). Hernias requiring repair were only identified in the MIS-RP group (0.12%). CONCLUSION: When considering surgical approach, rectal and large bowel injuries were more common in ORP, while vascular injuries and hernia repair were more common in MIS-RP. Our findings can be used in counseling patients and identifying risk factors and strategies to reduce these complications.

Lessons from Pharmacovigilance: Pulmonary Immune-Related Adverse Events After Immune Checkpoint Inhibitor Therapy.

PURPOSE: To characterize pulmonary toxicities associated with the use of novel immune checkpoint inhibitors METHODS: Adverse event reports from immune checkpoint inhibitors targeting PD-1/L1 and CTLA-4 were captured from the W.H.O pharmacovigilance database (VigiBase) up until Dec. 31st 2019 and were analyzed to evaluate for measures of association between the use of immune checkpoint inhibitors and pulmonary toxicities. Disproportionality analysis using both frequentist and Bayesian approaches were used to detect signals between pulmonary immune-related adverse events and the use of these agents. RESULTS: A total of 9202 adverse pulmonary immune checkpoint inhibitor-related events were captured up until 2019. Adverse pulmonary events were compromised of 1305 airway, 18 alveolar, 5491 interstitial, 898 pleural, 560 vascular and 939 non-specific pulmonary events. We found a common association between all immune checkpoint inhibitors studied and pneumonitis, interstitial lung disease, pulmonary embolism and respiratory failure. We also noted other associations between immune checkpoint inhibitors, however not as uniformly across agents. Most of these immune-related adverse drug reactions were noted to be severe and accounted for a significant source of mortality in the reported cases. CONCLUSION: Immune checkpoint inhibitors are associated with a spectrum of inflammatory pulmonary toxicities. The breadth of pulmonary complications and prevalence may be underappreciated with the use of these agents.

A tissue graft model of DNA damage response in the normal and malignant human prostate.

PURPOSE: DNA damage responses are relevant to prostate cancer initiation, progression and treatment. Few models of the normal and malignant human prostate that maintain stromal-epithelial interactions in vivo exist in which to study DNA damage responses. We evaluated the feasibility of maintaining tissue slice grafts at subcutaneous vs subrenal capsular sites in RAG2(-/-)γC(-/-) mice to study the DNA damage responses of normal and malignant glands. MATERIALS AND METHODS: We compared the take rate and histology of tissue slice grafts from fresh, precision cut surgical specimens that were maintained for 1 to 4 weeks in subcutaneous vs subrenal capsular sites. Induction of γH2AX, p53, ATM and apoptosis was evaluated as a measure of the DNA damage response after irradiation. RESULTS: The take rate of subcutaneous tissue slice grafts was higher than typically reported but lower than at the subrenal capsular site. Subcutaneous tissue slice grafts frequently showed basal cell hyperplasia, squamous metaplasia and cystic atrophy, and cancer did not survive. In contrast, normal and malignant histology was well maintained in subrenal capsular tissue slice grafts. Regardless of implantation site the induction of γH2AX and ATM occurred in tissue slice graft epithelium 1 hour after irradiation and decreased to basal level by 24 hours, indicating DNA damage recognition and repair. As observed previously in prostatic ex vivo models, p53 was not activated. Notably, tumor but not normal cells responded to irradiation by undergoing apoptosis. CONCLUSIONS: To our knowledge this is the first study of DNA damage responses in a patient derived prostate tissue graft model. The subrenal capsular site of RAG2(-/-)γC(-/-) mice optimally maintains normal and malignant histology and function, permitting novel studies of DNA damage responses in a physiological context.

Surgical Outcomes and Genomic Insights of Nonclear Cell Renal Cell Carcinoma with Synchronous and Metachronous Nodal Disease.

INTRODUCTION: Oncological outcomes in patients with nonclear cell renal cell carcinoma (non-ccRCC) treated with surgery for locoregional nodal disease (ND) remain incompletely characterized. The objective was to investigate the characteristics and outcomes of non-ccRCC patients treated with lymph node dissection (LND) and salvage-LND (S-LND). METHODS: A total of 1627 patients underwent nephrectomy for nonmetastatic non-ccRCC at Memorial Sloan Kettering Cancer Center between 2007 and 2023. Histology was grouped as papillary, chromophobe, unclassified, and rare subtypes. Retrospective evaluation identified 2.5% (n = 40) of patients with nodal disease at time of nephrectomy (synchronous-ND) and 1.1% (n = 18) with metachronous nodal disease limited to the retroperitoneum (metachronous-ND). Patients' demographics and tumor characteristics were recorded and evaluated by univariate and multivariate cox regression models. Recurrence-free survival (RFS) and overall survival (OS) were estimated by the Kaplan-Meier method. Patients who underwent tumor DNA sequencing during their clinical course were considered for genomic analysis. RESULTS: OS trended toward longer in metachronous-ND (51 vs 105 months; P = .2), though 23% of patients with synchronous-ND were recurrence-free at 45 months median follow-up. In multivariate analysis, rare histologies were associated with decreased OS (P = .030) and metachronous-ND with improved OS (P = .036). RFS and OS after S-LND was 15 and 96 months, respectively. Late onset of metachronous-ND/recurrence was associated with improved OS (P = .008). Genetic alterations in SETD2, TP53, B2M, and FGFR3 were exclusively seen in synchronous-ND, and tumor mutation burden (TMB) was also higher in patients with synchronous-ND (P = .016). CONCLUSIONS: Patients with metachronous-ND tend to have prolonged OS compared to synchronous-ND, but a substantial portion of patients with synchronous-ND still enter a durable disease-free state following LND. S-LND can likewise provide long-term survival, particularly in patients with longer time to metachronous nodal recurrence. Synchronous-ND was associated with SETD2, TP53, and NF2 alteration as well as higher TMB.

Surgical outcomes of cytoreductive nephrectomy in patients receiving systemic immunotherapy for advanced renal cell carcinoma.

PURPOSE: The use of systemic immune checkpoint blockade before surgery is increasing in patients with metastatic renal cell carcinoma, however, the safety and feasibility of performing consolidative cytoreductive nephrectomy after the administration of systemic therapy are not well described. PATIENTS AND METHODS: A retrospective review of patients undergoing nephrectomy was performed using our prospectively maintained institutional database. Patients who received preoperative systemic immunotherapy were identified, and the risk of postoperative complications were compared to those who underwent surgery without upfront systemic treatment. Perioperative characteristics and surgical complications within 90 days following surgery were recorded. RESULTS: Overall, we identified 220 patients who underwent cytoreductive nephrectomy from April 2015 to December 2022, of which 46 patients (21%) received systemic therapy before undergoing surgery. Unadjusted rates of surgical complications included 20% (n = 35) in patients who did not receive upfront systemic therapy and 20% (n = 9) in those who received upfront systemic immunotherapy. In our propensity score analysis, there was no statistically significant association between receipt of upfront immunotherapy and 90-day surgical complications [odds ratio (OR): 1.82, 95% confidence interval (CI): 0.59-5.14; P = 0.3]. This model, however, demonstrated an association between receipt of upfront immunotherapy and an increased odds of requiring a blood transfusion [OR: 4.53, 95% CI: 1.83-11.7; P = 0.001]. CONCLUSION: In our cohort, there was no significant difference in surgical complications among patients who received systemic therapy before surgery compared to those who did not receive upfront systemic therapy. Cytoreductive nephrectomy is safe and with low rates of complications following the use of systemic therapy.

Patient-derived tissue slice grafts accurately depict response of high-risk primary prostate cancer to androgen deprivation therapy.

BACKGROUND: Effective eradication of high-risk primary prostate cancer (HRPCa) could significantly decrease mortality from prostate cancer. However, the discovery of curative therapies for HRPCa is hampered by the lack of authentic preclinical models. METHODS: We improved upon tumorgraft models that have been shown to predict drug response in other cancer types by implanting thin, precision-cut slices of HRPCa under the renal capsule of immunodeficient mice. Tissue slice grafts (TSGs) from 6 cases of HRPCa were established in mice. Following androgen deprivation by castration, TSGs were recovered and the presence and phenotype of cancer cells were evaluated. RESULTS: High-grade cancer in TSGs generated from HRPCa displayed characteristic Gleason patterns and biomarker expression. Response to androgen deprivation therapy (ADT) was as in humans, with some cases exhibiting complete pathologic regression and others showing resistance to castration. As in humans, ADT decreased cell proliferation and prostate-specific antigen expression in TSGs. Adverse pathological features of parent HRPCa were associated with lack of regression of cancer in corresponding TSGs after ADT. Castration-resistant cancer cells remaining in TSGs showed upregulated expression of androgen receptor target genes, as occurs in castration-resistant prostate cancer (CRPC) in humans. Finally, a rare subset of castration-resistant cancer cells in TSGs underwent epithelial-mesenchymal transition, a process also observed in CRPC in humans. CONCLUSIONS: Our study demonstrates the feasibility of generating TSGs from multiple patients and of generating a relatively large number of TSGs from the same HRPCa specimen with similar cell composition and histology among control and experimental samples in an in vivo setting. The authentic response of TSGs to ADT, which has been extensively characterized in humans, suggests that TSGs can serve as a surrogate model for clinical trials to achieve rapid and less expensive screening of therapeutics for HRPCa and primary CRPC.

Advances in Imaging-Based Biomarkers in Renal Cell Carcinoma: A Critical Analysis of the Current Literature.

Cross-sectional imaging is the standard diagnostic tool to determine underlying biology in renal masses, which is crucial for subsequent treatment. Currently, standard CT imaging is limited in its ability to differentiate benign from malignant disease. Therefore, various modalities have been investigated to identify imaging-based parameters to improve the noninvasive diagnosis of renal masses and renal cell carcinoma (RCC) subtypes. MRI was reported to predict grading of RCC and to identify RCC subtypes, and has been shown in a small cohort to predict the response to targeted therapy. Dynamic imaging is promising for the staging and diagnosis of RCC. PET/CT radiotracers, such as 18F-fluorodeoxyglucose (FDG), 124I-cG250, radiolabeled prostate-specific membrane antigen (PSMA), and 11C-acetate, have been reported to improve the identification of histology, grading, detection of metastasis, and assessment of response to systemic therapy, and to predict oncological outcomes. Moreover, 99Tc-sestamibi and SPECT scans have shown promising results in distinguishing low-grade RCC from benign lesions. Radiomics has been used to further characterize renal masses based on semantic and textural analyses. In preliminary studies, integrated machine learning algorithms using radiomics proved to be more accurate in distinguishing benign from malignant renal masses compared to radiologists' interpretations. Radiomics and radiogenomics are used to complement risk classification models to predict oncological outcomes. Imaging-based biomarkers hold strong potential in RCC, but require standardization and external validation before integration into clinical routines.

The Natural History of Renal-Cell Carcinoma with Sarcomatoid Differentiation, a Stage-by-Stage Analysis.

BACKGROUND: Sarcomatoid differentiation in patients diagnosed with renal cell carcinoma (sRCC) imply aggressive behavior and often metastatic disease at the time of diagnosis. We aim to examine the overall survival (OS) in patients with sRCC using the National Cancer Database (NCDB). MATERIALS AND METHODS: We identified patients diagnosed with sRCC between 2010-2015. We employed Kaplan-Meier curves and multivariable Cox proportional hazards regression models to examine the impact of several potential risk factors on OS in patients diagnosed with sRCC. RESULTS: In total, 8582 patients with renal cancer were found to have sarcomatoid differentiation, with 4105 patients (47.8%) being diagnosed with AJCC stage IV disease. The median OS was 17.2 months (IQR 5.4, 68.7 months). Compared to patients who did not undergo surgery, OS was significantly longer in patients undergoing partial or total nephrectomy across all stages. This result remained consistent on multivariable Cox proportional hazards regression adjusting for patient and tumor characteristics (Surgery: Hazard ratio 0.54, 95%Confidence interval 0.43 - 0.68, P < .001). CONCLUSION: In our cohort sRCC was found to have an unfavorable median OS, which was mainly caused by the high number of cases diagnosed with late-stage disease. Additionally, surgery was associated with favorable OS across all stages. This study supports the notion that surgical therapy, even in the setting of cytoreductive surgery, provides a survival benefit in patients with sRCC.

Transcript levels of androgen receptor variant AR-V1 or AR-V7 do not predict recurrence in patients with prostate cancer at indeterminate risk for progression.

PURPOSE: AR-V7, a ligand independent splice variant of androgen receptor, may support the growth of castration resistant prostate cancer and have prognostic value. Another variant, AR-V1, interferes with AR-V7 activity. We investigated whether AR-V7 or V1 expression would predict biochemical recurrence in men at indeterminate (about 50%) risk for progression following radical prostatectomy. MATERIALS AND METHODS: AR-V7 and V1 transcripts in a mixed grade cohort of 53 men in whom cancer contained 30% to 70% Gleason grade 4/5 and in a grade 3 only cohort of 52 were measured using a branched chain DNA assay. Spearman rank correlations of the transcripts, and histomorphological and clinical variables were determined. AR-V7 and V1 levels were assessed as determinants of recurrence in the mixed grade cohort by logistic regression and survival analysis. The impact of TMPRSS2-ERG gene fusion on prognosis was also evaluated. RESULTS: Neither AR-V7 nor V1 levels in grade 3 or 4/5 cancer in the mixed grade cohort were associated with recurrence or time to recurrence. However, AR-V7 and V1 inversely correlated with serum prostate specific antigen and positively correlated with age. The AR-V1 level in grade 3 cancer in the grade 3 only cohort was higher than in grade 3 or grade 4/5 components of mixed grade cancer. TMPRSS2-ERG fusion was not associated with AR-V7, AR-V1 or recurrence but it was associated with the percent of grade 4/5 cancer. CONCLUSIONS: The AR-V1 or V7 transcript level does not predict recurrence in patients with high grade prostate cancer at indeterminate risk for progression. Grade 3 cancer in mixed grade tumors may differ from 100% grade 3 cancer, at least in AR-V1 expression.

Immune checkpoint inhibitor monotherapy is associated with less cardiac toxicity than combination therapy.

BACKGROUND: Treatment options for many cancers include immune checkpoint inhibitor (ICI) monotherapy and combination therapy with impressive clinical benefit across cancers. We sought to define the comparative cardiac risks of ICI combination and monotherapy. METHODS: We used VigiBase, the World Health Organization pharmacovigilance database, to identify cardiac ADRs (cADRs), such as carditis, heart failure, arrhythmia, myocardial infarction, and valvular dysfunction, related to ICI therapy. To explore possible relationships, we used the reporting odds ratio (ROR) as a proxy of relative risk. A lower bound of a 95% confidence interval of ROR &gt; 1 reflects a disproportionality signal that more ADRs are observed than expected due to chance. RESULTS: We found 2278 cADR for ICI monotherapy and 353 for ICI combination therapy. Combination therapy was associated with significantly higher odds of carditis (ROR 6.9, 95% CI: 5.6-8.3) versus ICI monotherapy (ROR 5.0, 95% CI: 4.6-5.4). Carditis in ICI combination therapy was fatal in 23.4% of reported ADRs, compared to 15.8% for ICI monotherapy (P = 0.058). CONCLUSIONS: Using validated pharmacovigilance methodology, we found increased odds of carditis for all ICI therapies, with the highest odds for combination therapy. Given the substantial risk of severe ADR and death, clinicians should consider these findings when prescribing checkpoint inhibitors.

Temporal Trends in the Incidence of Testicular Cancer in the United States over the Past Four Decades.

Testicular cancer is the most commonly diagnosed solid-organ neoplasm among young men, with variable incidence across racial groups. Testicular cancer incidence has increased since the 1970s, most notably among white men. Such trends in testicular cancer remain poorly understood. We investigated age-adjusted incidence rates of testicular cancer from 1975 to 2015 using Surveillance, Epidemiology and End Results data to further understand the nature of the temporal trends and potential drivers of disease. Across this time period, white men had the highest incidence and the largest increase in rate; however, we also note more recent increases in the incidence of testicular cancer across all racial groups being examined. PATIENT SUMMARY: We analyzed the rate of testicular cancer in the United States between 1975 and 2015. In that time, white patients had the highest rate and increase in rate of testicular cancer, but non-white patients also had increasing rates of disease.

Recovery from minimally invasive vs. open surgery in kidney cancer patients: Opioid use and workplace absenteeism.

PURPOSE: Does surgical approach (minimally invasive vs. open) and type (radical vs. partial nephrectomy) affects opioid use and workplace absenteeism. MATERIALS AND METHODS: Retrospective multivariable regression analysis of 2,646 opioid-naïve patients between 18 and 64 undergoing radical or partial nephrectomy via either a minimally invasive vs. open approach for kidney cancer in the United States between 2012 and 2017 drawn from the IBM Watson Health Database was performed. Outcomes included: (1) opioid use in opioid-naïve patients as measured by opioid prescriptions in the post-operative setting at early, intermediate and prolonged time periods and (2) workplace absenteeism after surgery. RESULTS: Patients undergoing minimally invasive surgery had a lower odds of opioid use in the early and intermediate post-operative periods (early: odds ratio [OR], 0.77; 95% confidence interval [CI], 0.62-0.97; p=0.02, intermediate: OR, 0.60; 95% CI, 0.48-0.75; p<0.01), but not in the prolonged setting (prolonged: OR, 1.00; 95% CI, 0.75-1.34; p=0.98) and had earlier return to work (minimally invasive vs. open: -10.53 days; 95% CI, -17.79 to -3.26; p<0.01). Controlling for approach, patient undergoing partial nephrectomy had lower rates of opioid use across all time periods examined and returned to work earlier than patients undergoing radical nephrectomy (partial vs. radical: -14.41 days; 95% CI, -21.22 to -7.60; p<0.01). CONCLUSIONS: Patients undergoing various forms of surgery for kidney cancer had lower rates of peri-operative opioid use, fewer days of workplace absenteeism, but no difference in long-term rates of opioid use in patients undergoing minimally invasive as compared to open surgery.

Risk factors and reasons for reoperation after radical cystectomy.

PURPOSE: Reoperation after radical cystectomy (RC) is common but the types of reoperation after RC and associated risk factors have not been fully characterized. Here, we provide a detailed, contemporary account of the factors that drive surgical reoperation within the first 30-days after surgery, identify at risk patient populations, and describe common reoperations. MATERIALS AND METHODS: The American College of Surgeons National Surgical Quality Improvement Program database (2012-2017) was analyzed to identify 30-day reoperation rates after RC. Captured variables included demographic, preoperative, operative, and postoperative characteristics. Postoperative characteristics included complications, including types of reoperation, length of stay, unplanned readmissions, and discharge destination. Pearson chi-squared and multivariable logistic regression models were used for analysis. RESULTS: A total of 10,848 patients underwent RC and there were 633 (5.84%) unplanned reoperations. On multivariable logistic regression, patient factors associated with increased risk of reoperation included longer operative times at index procedure (>90th percentile operative time) (OR1.41 [1.08-1.83], P = 0.02), smoking (OR1.34 [1.11-1.63], P < 0.01), obesity (BMI≥30) (OR 1.29 [1.04-1.60], P = 0.02) and chronic obstructive pulmonary disease (OR1.74 [1.36-2.3], P < 0.01). Other significant factors included clinically significant hypertension, perioperative blood transfusion, and male sex. The most common reoperation procedures were those performed on the gastrointestinal tract, accounting for 60.59% (349) of all reoperations, followed by skin/subcutaneous procedures 14.76% (85), followed by Genitourinary procedures at 8.16% (47). Patients who underwent reoperation were at higher risk for readmission, discharge to a facility, and death (P < 0.01). CONCLUSION: Reoperation after RC is associated with approximately 5% rate of reoperation within 30 days of surgery. The most common reason for reoperation was related to the gastrointestinal tract, accounting for more than 60% of all reoperations. Risk factors for reoperation included longer surgical times, smoking, obesity, chronic obstructive pulmonary disease, perioperative blood transfusion, and clinically significant hypertension. Knowledge of these factors can aid in operative planning and counseling and lead to possible strategies to reduce reoperations in the early perioperative setting.

Trends in Adherence to Thromboprophylaxis Guideline in Patients Undergoing Radical Cystectomy.

OBJECTIVE: To examine the use of in-hospital pharmacologic thromboprophylaxis (PTP) in patients undergoing radical cystectomy between 2004 and 2014 and to assess the risk of venous thromboembolism (VTE) across the study period. MATERIAL AND METHODS: We identified 8322 patients without contraindications to PTP undergoing radical cystectomy in the US using the Premier Healthcare Database. Nonparametric Wilcoxon type test for trend was employed to examine the trend of PTP utilization across the study period. Ensuing, we employed multivariable logistic regression and generalized linear regression models to examine the odds of receiving PTP and the risk of being diagnosed with VTE, respectively. RESULTS: Based on VTE risk-stratification, the majority of patients (87.8%) qualified as "high-risk." Across the study period the use of PTP increased (Odds ratio 1.02, 95% confidence interval (CI) 1.00-1.03, P = .044), but remained underutilized as the maximum percentage of patients receiving in-hospital PTP did not exceed 58.6%. The risk of VTE did not vary across the study period (risk ratio 0.97, 95%CI 0.92-1.02, P = .178). CONCLUSION: Utilization of PTP increased throughout the study period, while the risk of VTE did not change. Future studies are necessary to improve implementation of guideline-driven care, as PTP remained underutilized throughout the study period.

Inhibition of monoamine oxidase A promotes secretory differentiation in basal prostatic epithelial cells.

Monoamine oxidase A (MAO-A) expression is associated with high-grade prostate cancer. Immunohistochemistry showed that MAO-A is also expressed in the basal epithelial cells of normal prostate glands. Using cultured primary prostatic epithelial cells as a model, we showed that MAO-A prevents basal epithelial cells from differentiating into secretory cells. Under differentiation-promoting conditions, clorgyline, an irreversible MAO-A inhibitor, induced secretory cell-like morphology and repressed expression of cytokeratin 14, a basal cell marker. More importantly, clorgyline induced mRNA and protein expression of androgen receptor (AR), a hallmark of secretory epithelial cells. In clorgyline-treated cells, androgen induced luciferase activity controlled by the promoter of prostate-specific antigen, an AR target gene, in a dose-dependent manner. This activity was blocked by the AR antagonist Casodex, showing that AR is functional. In turn, androgen decreased MAO-A expression in clorgyline-treated, secretory-like cells. Our results demonstrated that cultured basal epithelial cells have the potential to differentiate into secretory cells, and that inhibition of MAO-A is a key factor in promoting this process. Increased expression of MAO-A in high-grade prostate cancer may be an important contributor to its de-differentiated phenotype, raising the possibility that MAO-A inhibition may restore differentiation and reverse the aggressive behavior of high-grade cancer.