Hamid Emamekhoo

Clinical significance of D4A in prostate cancer therapy with abiraterone

Androgen deprivation therapy (ADT), either by surgical or medical castration depletes testicular production of testosterone (T) and has long been considered as the mainstay of upfront treatment for advanced prostate cancer. Despite the initial response to this treatment, disease progression to castration-resistant prostate cancer (CRPC) usually occurs. The adrenal production of androgen precursor steroids, such as dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEA-S), permits intratumoral production of T and 5α-dihydrotestosterone (DHT), activation of androgen receptor (AR) and AR-dependent gene expression. Abiraterone (Abi; given as Abi acetate) and enzalutamide (Enz) are 2 of the agents that target different parts of the androgen pathway by blocking androgen production and signaling, ultimately improving overall survival for patients with metastatic CRPC.1,2 Abi is a potent inhibitor of 17α-hydroxylase/17,20-lyase (CYP17A1), which is a key enzyme required for DHEA and DHEA-S production. Synthesis of DHT, the most potent androgen, from DHEA necessitates a series of enzymes, including 3β-hydroxysteroid dehydrogenase (3βHSD), steroid-5α-reductase (SRD5A), and 17β-hydroxysteroid dehydrogenase (17βHSD) isoenzymes. This process enables the conversion of ADT-responsive prostate cancer into CRPC. Multiple retrospective reviews have shown the limited efficacy of Enz after Abi treatment failure and vice versa.3,4 To date there are very little data on the appropriate sequence of Enz and Abi utilization, which might thereby maximize the potential efficacy and duration of response to treatment with these agents. Our recently published research demonstrates that Δ4, 3-keto-abi (D4A) is a metabolite of Abi that is formed in patients with prostate cancer and has CYP17A1 inhibition activity that is comparable to Abi.5 Furthermore, D4A inhibits 3βHSD (a key enzyme involved in CRPC progression) more potently than Abi and at higher concentrations it demonstrates significant SRD5A inhibitory effects as well. Moreover, although Abi has been shown to have AR antagonistic activity,6 we observed more potent AR inhibition activity with D4A that is comparable to Enz in our experiments.5 As a result, by targeting multiple steps of the AR signaling pathway, D4A showed a significant increase in progression free survival compared to Abi and Enz in our xenograft models, suggesting that it might play an important role in the clinical activity of Abi in CRPC patients. Abi is converted to D4A by 3βHSD. Increased 3βHSD enzymatic function, with the HSD3B1(1245C) genetic variant encoding a missense in 3βHSD1 as one known mechanism, also increases intratumoral flux to DHT that may result in the development of treatment resistance.7 Therefore, D4A conversion ratio could serve as an indicator of 3βHSD activity and ultimately may predict resistance to hormonal therapy for prostate cancer. On the other hand, higher 3βHSD activity would translate into a higher D4A concentration, which is a more potent metabolite than Abi as described above. Although the Abi to D4A conversion ratio is low (at about 5%) in most patients, it appears to be quite variable. A higher conversion ratio might mimic conditions of treatment with Enz, particularly given the AR antagonist activity of D4A. In other words, 3βHSD activity level in a patient might be helpful in predicting the potential response to Abi and ultimately a patient with higher concentration of D4A with Abi treatment might be less likely to benefit from subsequent Enz treatment. Conversely, increasing D4A levels by increasing Abi concentrations or the conversion to D4A might increase the clinical benefit of treatment with Abi. In addition, because 3βHSD is required for mineralocorticoid synthesis, 3βHSD inhibition by D4A might reduce mineralocorticoid production that could translate into a better side effect profile (less hypertension and hypokalemia) and potentially lower dose of prednisone requirement in patients with higher D4A levels. These questions have yet to be answered in clinical studies. Finally, it is possible that steroidogenic metabolites of Abi are not limited to D4A, and that other metabolites with clinically relevant biochemical activity contribute to response and resistance to treatment with Abi.

HSD3B1(1245A>C) variant regulates dueling abiraterone metabolite effects in prostate cancer

BACKGROUND. A common germline variant in HSD3B1(1245A>C) encodes for a hyperactive 3&bgr;-hydroxysteroid dehydrogenase 1 (3&bgr;HSD1) missense that increases metabolic flux from extragonadal precursor steroids to DHT synthesis in prostate cancer. Enabling of extragonadal DHT synthesis by HSD3B1(1245C) predicts for more rapid clinical resistance to castration and sensitivity to extragonadal androgen synthesis inhibition. HSD3B1(1245C) thus appears to define a subgroup of patients who benefit from blocking extragonadal androgens. However, abiraterone, which is administered to block extragonadal androgens, is a steroidal drug that is metabolized by 3&bgr;HSD1 to multiple steroidal metabolites, including 3-keto-5&agr;-abiraterone, which stimulates the androgen receptor. Our objective was to determine if HSD3B1(1245C) inheritance is associated with increased 3-keto-5&agr;-abiraterone synthesis in patients. METHODS. First, we characterized the pharmacokinetics of 7 steroidal abiraterone metabolites in 15 healthy volunteers. Second, we determined the association between serum 3-keto-5&agr;-abiraterone levels and HSD3B1 genotype in 30 patients treated with abiraterone acetate (AA) after correcting for the determined pharmacokinetics. RESULTS. Patients who inherit 0, 1, and 2 copies of HSD3B1(1245C) have a stepwise increase in normalized 3-keto-5&agr;-abiraterone (0.04 ng/ml, 2.60 ng/ml, and 2.70 ng/ml, respectively; P = 0.002). CONCLUSION. Increased generation of 3-keto-5&agr;-abiraterone in patients with HSD3B1(1245C) might partially negate abiraterone benefits in these patients who are otherwise more likely to benefit from CYP17A1 inhibition. FUNDING. Prostate Cancer Foundation Challenge Award, National Cancer Institute.

Myeloid-derived suppressors cells (MDSC) correlate with clinicopathologic factors and pathologic complete response (pCR) in patients with urothelial carcinoma (UC) undergoing cystectomy

BACKGROUND Myeloid derived suppressor cells (MDSC) are heterogeneous immunosuppressive cells with potential predictive and prognostic roles in cancer. The association between MDSC, clinicopathologic factors, and pathologic response in patients with bladder urothelial carcinoma (UC) was explored. METHODS Peripheral blood or tissue were collected from patients with UC undergoing definitive surgery. MDSCs levels were measured in peripheral blood mononuclear cells and fresh tumor tissue. MDSCs were identified by flow cytometry and defined as total MDSC (T-MDSC) CD33+/HLADR-. From this population, 3 subsets were identified: polymorphonuclear-MDSC (PMN-MDSC) defined as CD33+/HLADR-/CD15+/CD14-, monocytic-MDSC (M-MDSC) defined as CD33+/HLADR-/CD15-/CD14+, and immature-MDSC (I-MDSC) defined as CD33+/HLADR-/CD15-/CD14-. MDSC populations were presented as % of live nucleated blood cells. Spearman correlations (r) and Wilcoxon rank sum test were used to assess correlations between MDSC populations, clinicopathologic factors, and pathologic complete response (pCR). RESULTS 85 patients scheduled to undergo cystectomy from February 2015 through Dec 2016 were included. All patients had blood drawn for analysis and 23 patients had residual tumor tissue collected for analysis at the time of surgery. Of these 85, 74 (87%) were men with a median age at diagnosis of 68 (range: 44-87). Pure UC was the most common histology (75%); 28 (35%) patients had prior treatment with intravesical therapy and 36 (42%) were treated with neoadjuvant chemotherapy, primarily gemcitabine plus cisplatin (n = 24). On surgical pathology, 18 (21%) of the patients had pCR, 11 (13%) had positive lymph nodes, and 20 patients (24%) had lymphovascular invasion. Statistically significant associations were found between circulating MDSC levels and pCR rates (P<0.01), absolute neutrophil-lymphocyte ratio (P = 0.008), and histology (P = 0.01). Tumor % M-MDSCs were negatively associated with lymphovascular invasion (P = 0.04). There were no significant correlations between peripheral blood mononuclear cells and tumor MDSC subtypes. CONCLUSIONS Blood and tissue MDSC levels correlate with several clinicopathologic factors and may predict for pCR. Future studies are needed to highlight the role of MDSC in predicting long-term outcomes and to determine the clinical implications of these findings.

Prognostic Factors and Risk Stratification in Invasive Upper Tract Urothelial Carcinoma

Micro‐Abstract Upper tract urothelial carcinoma is a rare disease and most of the treatment guidelines are extrapolated from urothelial carcinoma of the bladder. In this retrospective study, we were able to identify baseline features, treatment patterns, and prognostic factors, which could be used in risk stratification, management decision‐making, and disease‐specific clinical trial design. Background: Upper tract urothelial carcinoma (UTUC) accounts for approximately 5% of all urothelial cancers. Because of similarities in morphology and histology between UTUC and urothelial carcinoma of the bladder, most treatment guidelines used for UTUC are extrapolated from the urothelial bladder carcinoma setting. With the emergence of new treatment modalities, such as immunotherapy, UTUC‐specific prognostic and predictive models are needed. Patients and Methods: A retrospective study of 454 UTUC patients who received surgery at Cleveland Clinic (1995‐2014) was conducted. Univariable and multivariable analysis (MVA) was used to identify independent predictors of progression‐free survival (PFS) and overall survival (OS). Results: Two hundred eighty‐six patients with invasive UTUC were identified with pT1, pT2, pT3, and pT4 in 93 (33%), 51 (18%), 126 (44%), and 16 (6%), respectively. Most patients (76%) had laparoscopic nephroureterectomy, 14% had positive invasive surgical margins, and 22% had multifocal tumors. All patients had urothelial carcinoma as primary histology, 93 of 183 (51%) with available follow‐up data had disease recurrence. Estimated median PFS was 17.2 months (95% confidence interval [CI], 13.1‐39.3). In MVA, pT stage (P = .0005), positive margins (P = .04), and age older than 70 years (P = .002) independently correlated with PFS. Overall, 101 patients (37%) of 272 patients with available data died with estimated median OS of 64.5 months (95% CI, 39.3‐107.4); median follow‐up was 39.5 (range, 0.3‐186) months in patients alive and recurrence‐free at last follow‐up. In MVA, lymphovascular invasion (P = .005), tumor size (P = .0005), age (P = .005), and pT stage (P = .03) independently predicted OS. Using these factors, 3 prognostic groups for PFS and 2 for OS were identified. Conclusion: Clinical‐pathological parameters can be prognostic in UTUC and might inform clinical trial design and decision‐making.

Relationship of smoking status to genomic profile, chemotherapy response and clinical outcome in patients with advanced urothelial carcinoma

Smoking has been linked to urothelial carcinoma (UC), but the implications on genomic profile and therapeutic response are poorly understood. To determine how smoking history impacts genomic profile and chemotherapy response, clinicopathologic data was collected for patients with metastatic UC (mUC) across 3 academic medical centers and comprehensive genomic profiling (CGP) was performed through a CLIA-certified lab. Unsupervised hierarchical clustering based on smoking status was used to categorize the frequency of genomic alterations (GAs) amongst current smokers (CS), ex-smokers (ES) and non-smokers (NS), and survival was compared in these subsets. Fishers exact test identified significant associations between GAs and smoking status. Amongst 83 patients, 23%, 55% and 22% were CS, ES, and NS, respectively, and 95% of patients had stage IV disease. With a median follow up of 14.4 months, the median overall survival (OS) was significantly higher in NS and ES (combined) as compared to CS (51.6 vs 15.6 months; P = 0.04). Of 315 cancer-related genes and 31 genes often related to rearrangement tested, heatmaps show some variations amongst the subsets. GAs in NSD1 were more frequent in CS as compared to other groups (P < 0.001). CS status negatively impacts OS in patients with mUC and is associated with genomic alterations that could have therapeutic implications.

Treatment selection for men with metastatic prostate cancer who progress on upfront chemo-hormonal therapy

Androgen deprivation therapy plus docetaxel (D‐ADT) increases overall survival (OS) in men with high‐volume, metastatic hormone‐sensitive prostate cancer (mHSPC). Although the vast majority of men initially respond to D‐ADT, most will progress and develop castration‐resistant prostate cancer (CRPC). Little is known about the optimal treatment sequence for men with progressive disease on D‐ADT.

ATM/RB1 mutations predict shorter overall survival in urothelial cancer

Background Mutations of DNA repair genes, e.g. ATM/RB1, are frequently found in urothelial cancer (UC) and have been associated with better response to cisplatin-based chemotherapy. Further external validation of the prognostic value of ATM/RB1 mutations in UC can inform clinical decision making and trial designs. Results In the discovery dataset, ATM/RB1 mutations were present in 24% of patients and were associated with shorter OS (adjusted HR 2.67, 95% CI, 1.45–4.92, p = 0.002). There was a higher mutation load in patients carrying ATM/RB1 mutations (median mutation load: 6.7 versus 5.5 per Mb, p = 0.072). In the validation dataset, ATM/RB1 mutations were present in 22.2% of patients and were non-significantly associated with shorter OS (adjusted HR 1.87, 95% CI, 0.97–3.59, p = 0.06) and higher mutation load (median mutation load: 8.1 versus 7.2 per Mb, p = 0.126). Materials and Methods Exome sequencing data of 130 bladder UC patients from The Cancer Genome Atlas (TCGA) dataset were analyzed as a discovery cohort to determine the prognostic value of ATM/RB1 mutations. Results were validated in an independent cohort of 81 advanced UC patients. Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI) to compare overall survival (OS). Conclusions ATM/RB1 mutations may be a biomarker of poor prognosis in unselected UC patients and may correlate with higher mutational load. Further studies are required to determine factors that can further stratify prognosis and evaluate predictive role of ATM/RB1 mutation status to immunotherapy and platinum-based chemotherapy.

Evaluation of Response to Enzalutamide Consecutively After Abiraterone Acetate/Prednisone Failure in Patients With Metastatic Castration-resistant Prostate Cancer

Introduction: Treatment of metastatic castration‐resistant prostate cancer (mCRPC) has evolved significantly during the past decade, and the preferred combination and/or sequence of these treatments remains controversial. In this retrospective study, we explored clinical and pathologic factors that could predict response to consecutive treatment with enzalutamide (ENZA) after disease progression (PD) on abiraterone acetate and prednisone (AA/P). Patients and Methods: Data were collected from 40 consecutive patients with mCRPC who were treated with ENZA without other interim therapy after progression on AA/P. Results: The median time from prostate cancer initial diagnosis to AA/P treatment was 6.2 (range, 0.9‐16.3) years. The median prostate‐specific antigen (PSA) progression‐free survival (PSA‐PFS) from treatment initiation was 8.5 months (95% confidence interval [CI], 7.1‐10.1 months) and 2.3 months (95% CI, 1.8‐3.4 months) on AA/P and ENZA, respectively. The median time to PD from treatment initiation was 9.7 months (95% CI, 7.1‐12.4 months) and 3 months (95% CI, 2.3‐4.1 months) on AA/P and ENZA, respectively. The correlations were weak between the best percent change in PSA on ENZA and time from diagnosis to AA/P initiation, best absolute or percentage change in PSA on AA/P, time to PSA progression or PD on AA/P. Patients with longer than the median duration of treatment with AA/P (11.73 months) had longer PSA‐PFS on ENZA (median 2.8 vs. 1.9 months; P = .035). Conclusions: In this retrospective analysis, we did not find any clinical or pathologic factors associated with response to ENZA administered consecutively after AA/P. Patients with longer than median AA/P treatment duration had longer PSA‐PFS on ENZA. Further evaluations and validation are greatly needed.

Correlation of myeloid derived suppressor cell (MDSC) populations with clinicopathologic features in urothelial carcinoma (UC).

434 Background: MDSC are a heterogeneous population of potent immunosuppressive cells with potential predictive/prognostic significance in solid tumors. The association between MDSC and clinicopathologic features in patients (pts) with UC was investigated. Methods: Peripheral blood from 26 non-metastatic UC pts scheduled to undergo cystectomy or nephroureterectomy at Cleveland Clinic was collected. MDSC were enumerated in fresh unfractionated blood (WB) and in peripheral blood mononuclear cells (PBMC). (T)otal MDSC were defined as CD33+/HLADR-; out of T-MDSC, (G)ranulocytic (CD15+CD14-), (M)onocytic (CD15-CD14+) and (I)mmature (CD15-CD14-) MDSC were identified. CD11b MDSC (Linlo/HLADR-/CD33+/CD11b+) were identified in WB. MDSC populations were presented as % of live nucleated blood cells and as absolute numbers from WB. Wilcoxon rank sum test was used to assess associations between MDSC populations and clinicopathologic features. Due to the exploratory nature of the study, p < .10 was considered significa...

Evaluation of prognostic factors in upper tract urothelial carcinoma (UTUC).

372 Background: UTUC is relatively rare (5-10% of UC). Limited data on prognostic factors is available. Methods: A retrospective study of UTUC patients (pts) who had surgery (1995-2014) at Cleveland Clinic (n = 454) was conducted. Univariable (UVA) and multivariable (MVA) analysis (proportional hazards) with a stepwise selection algorithm (p = .10 and .05, as criteria for entry and retention in the model) was used to identify independent predictors of recurrence-free survival (RFS) and overall survival (OS). Results: 192 pts with invasive high grade UTUC were identified; median age at resection was 72; 69% men. 72% of pts had laparoscopic and 17% open nephrouretectomy, 23% had +ve margins (including bladder/ureter cuff), 22% had multifocal tumor. Median tumor size 3.5 cm (0.2-12); 70% had tumors < 5 cm; 65% pT3, 8% pT4 stage; among pts with lymph node (LN) dissection, 25% had +ve LN. All but 3 pts (2 sarcomatoid, 1 small cell) had primarily UC; 28% mixed UC histology; 40% CIS, 54% confirmed lymphovascular...