Human cytochrome P450 17A1 structures with metabolites of prostate cancer drug abiraterone reveal substrate-binding plasticity and a second binding site.

Abiraterone acetate is a first-line therapy for castration-resistant prostate cancer. This prodrug is deacetylated in vivo to abiraterone, which is a potent and specific inhibitor of cytochrome P450 17A1 (CYP17A1). CYP17A1 performs two sequential steps that are required for the biosynthesis of androgens that drive prostate cancer proliferation, analogous to estrogens in breast cancer. Abiraterone can be further metabolized in vivo on the steroid A ring to multiple metabolites that also inhibit CYP17A1. Despite its design as an active-site-directed substrate analog, abiraterone and its metabolites demonstrate mixed competitive/noncompetitive inhibition. To understand their binding, we solved the X-ray structures of CYP17A1 with three primary abiraterone metabolites. Despite different conformations of the steroid A ring and substituents, all three bound in the CYP17A1 active site with the steroid core packed against the I helix and the A ring C3 keto or hydroxyl oxygen forming a hydrogen bond with N202 similar to abiraterone itself. The structure of CYP17A1 with 3-keto, 5α-abiraterone was solved to 2.0 Å, the highest resolution to date for a CYP17A1 complex. This structure had additional electron density near the F/G loop, which is likely a second molecule of the inhibitor and which may explain the noncompetitive inhibition. Mutation of the adjacent Asn52 to Tyr positions its side chain in this space, maintains enzyme activity, and prevents binding of the peripheral ligand. Collectively, our findings provide further insight into abiraterone metabolite binding and CYP17A1 function.

Predicting abiraterone efficacy in advanced prostate cancer: Insights from marker of proliferation Ki67.

BACKGROUND: KI67 is a well-known biomarker reflecting cell proliferation. We aim to elucidate the predictive role of KI67 in the efficacy of abiraterone for patients with advanced prostate cancer (PCa). METHODS: Clinicopathological data of 152 men with metastatic PCa, who received abiraterone therapy were retrospectively collected. The KI67 positivity was examined by immunohistochemistry using the prostate biopsy specimen. The predictive value of KI67 on the therapeutic efficacy of abiraterone was explored using Kaplan-Meier curve and Cox regression analysis. The endpoints included prostate-specific antigen (PSA) progression-free survival (PSA-PFS), radiographic PFS (rPFS), and overall survival (OS). RESULTS: In total, 85/152 (55.9%) and 67/152 (44.1%) cases, respectively, received abiraterone at metastatic hormone-sensitive (mHSPC) and castration-resistant PCa (mCRPC) stage. The median KI67 positivity was 20% (interquartile range: 10%-30%). Overall, KI67 rate was not correlated with PSA response. Notably, an elevated KI67-positive rate strongly correlated with unfavorable abiraterone efficacy, with KI67 ≥ 30% and KI67 ≥ 20% identified as the optimal cutoffs for prognosis differentiation in mHSPC (median PSA-PFS: 11.43 Mo vs. 26.43 Mo, p < 0.001; median rPFS: 16.63 Mo vs. 31.90 Mo, p = 0.003; median OS: 21.77 Mo vs. not reach, p = 0.005) and mCRPC (median PSA-PFS: 7.17 Mo vs. 12.20 Mo, p = 0.029; median rPFS: 11.67 Mo vs. 16.47 Mo, p = 0.012; median OS: 21.67 Mo vs. not reach, p = 0.073) patients, respectively. Multivariate analysis supported the independent predictive value of KI67 on abiraterone efficacy. In subgroup analysis, an elevated KI67 expression was consistently associated with unfavorable outcomes in the majority of subgroups. Furthermore, data from another cohort of 79 PCa patients with RNA information showed that those with KI67 RNA levels above the median had a significantly shorter OS than those below the median (17.71 vs. 30.72 Mo, p = 0.035). CONCLUSIONS: This study highlights KI67 positivity in prostate biopsy as a strong predictor of abiraterone efficacy in advanced PCa. These insights will assist clinicians in anticipating clinical outcomes and refining treatment decisions for PCa patients.

Synthesis and Biological Evaluation of Methoxypolyethylene-Glycol-Substituted Abiraterone Derivatives as Potential Antiprostate Cancer Agents.

Globally, prostate cancer is the most commonly diagnosed tumor and a cause of death in older men. Abiraterone, an orally administered irreversible CYP17 inhibitor, is employed to treat prostate cancer. However, abiraterone has several clinical limitations, such as poor water solubility, low dissolution rate, low bioavailability, and toxic side effects in the liver and kidney. Therefore, there is a need to identify high-efficiency and low-toxicity water-soluble abiraterone derivatives. In this work, we aimed to design and synthesize a series of abiraterone derivatives by methoxypoly(ethylene glycol) (mPEG) modification. Their antitumor activities and toxicology were analyzed in vitro and in vivo. The most potent compound, 2e, retained the principle of action on the CYP17 enzyme target and significantly improved the abiraterone water solubility, cell permeability, and blood safety. No significant abnormalities were observed in toxicology. mPEG-modification significantly improved abiraterone's antitumor activity and efficiency while reducing the associated toxic effects. The finding will provide a theoretical basis for future clinical application of mPEG-modified abiraterone.

Effect of food and polymorphisms in SLCO2B1, CYP3A4 and UGT1A4 on pharmacokinetics of abiraterone and its metabolites in Chinese volunteers.

AIMS: Abiraterone acetate, a prodrug of abiraterone (ABI), provides an efficient therapeutic option for metastatic castration-resistant prostate cancer patients. ABI undergoes extensive metabolism in vivo and is transformed into active metabolites Δ4 -abiraterone and 3-keto-5α-abiraterone as well as inactive metabolites abiraterone sulfate and abiraterone N-oxide sulfate. We aimed to examine the effect of polymorphisms in SLCO2B1, CYP3A4 and UGT1A4 on the pharmacokinetics of ABI and its metabolites. METHODS: In this study, 81 healthy Chinese subjects were enrolled and divided into 2 groups for fasted (n = 45) and fed (n = 36) studies. Plasma samples were collected after administering a 250 mg abiraterone acetate tablet followed by liquid chromatography-tandem mass spectrometry analysis. Genotyping was performed on a MassARRAY system. The association between SLCO2B1, CYP3A4, UGT1A4 genotype and pharmacokinetic parameters of ABI and its metabolites was assessed. RESULTS: Food effect study demonstrated high fat meal remarkedly increased systemic exposure of ABI and its metabolites. The geometric mean ratio and 90% confidence interval of area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration (AUC0-t ) and maximum plasma concentration (Cmax ) of ABI in fed state vs. fasted state were 351.64% (286.86%-431.04%) and 478.45% (390.01%-586.94%), respectively, while the corresponding results were ranging from 145.11% to 269.42% and 150.10% to 478.45% for AUC0-t and Cmax of ABI metabolites in fed state vs. fasted state, respectively. The SLCO2B1 rs1077858 had a significant influence on AUC0-t and Cmax , while 7 other SLCO2B1 variants prolonged half-life of ABI under both fasted and fed conditions. As for ABI metabolites, the systemic exposure of Δ4 -abiraterone, abiraterone sulfate and abiraterone N-oxide sulfate as well as the elimination of 3-keto-5α-abiraterone were significantly affected by SLCO2B1 polymorphisms. Polymorphisms in CYP3A4 and UGT1A4 did not significantly affect pharmacokinetics of ABI and its metabolites. CONCLUSION: Polymorphisms in SLCO2B1 were significantly related to the pharmacokinetic variability of ABI and its metabolites under both fasted and fed conditions.

Evaluation of adherence to abiraterone therapy in prostate cancer patients based on a population pharmacokinetic model.

AIMS: Abiraterone treatment requires regular drug intake under fasting conditions due to pronounced food effect, which may impact patient adherence. The aim of this prospective study was to evaluate adherence to abiraterone treatment in patients with prostate cancer. To achieve this aim, an abiraterone population pharmacokinetic model was developed and patients' adherence has been estimated by comparison of measured levels of abiraterone with population model-based simulations. METHODS: A total of 1469 abiraterone plasma levels from 83 healthy volunteers collected in a bioequivalence study were analysed using a nonlinear mixed-effects model. Monte Carlo simulation was used to describe the theoretical distribution of abiraterone pharmacokinetic profiles at a dose of 1000 mg once daily. Adherence of 36 prostate cancer patients treated with abiraterone was then evaluated by comparing the real abiraterone concentration measured in each patient during follow-up visit with the theoretical distribution of profiles based on simulations. Patients whose abiraterone levels were ˂5th or ˃95th percentile of the distribution of simulated profiles were considered to be non-adherent. RESULTS: Based on this evaluation, 13 patients (36%) have been classified as non-adherent. We observed significant association (P = .0361) between richness of the breakfast and rate of non-adherence. Adherent patients reported significantly better overall condition in self-assessments (P = .0384). A trend towards a higher occurrence of adverse effects in non-adherent patients was observed. CONCLUSIONS: We developed an abiraterone population pharmacokinetic model and proposed an advanced approach to medical adherence evaluation. Due to the need for administration under fasting conditions, abiraterone therapy is associated with a relatively high rate of non-adherence.

Real-World Incidence and Severity of Hypertension Caused by Abiraterone Acetate in Patients With Metastatic Prostate Cancer.

BACKGROUND: Abiraterone acetate (AA) is used in treatment of patients with metastatic prostate cancer. Despite the survival advantage, AA is associated with hypertension due to mineralocorticoid excess syndrome. OBJECTIVE: We conducted a single-center retrospective analysis to evaluate the real-world incidence and severity of AA-induced hypertension. METHODS: Electronic health records were used to collect baseline characteristics and prostate cancer history. Patient data, including blood pressure at each 4 (±2)-week interval, were collected for 24 weeks after the initiation of AA therapy. The primary endpoint was the incidence and severity of AA-induced hypertension. The secondary endpoints include effect of different prednisone dosing regimens and prostate cancer types on hypertensive incidence and the impact of clinical pharmacists' involvement in managing AA-induced hypertension. RESULTS: A total of 142 patients who met our inclusion criteria received AA for metastatic prostate cancer, 73 (51.4%) with metastatic castration-resistant prostate cancer (mCRPC), and 69 (48.6%) with metastatic castration-sensitive prostate cancer (mCSPC). Of all, 43.7% experienced all-grade hypertension, and 28.2% experienced grade 3-4 hypertension. There was no difference in incidence of hypertension between patients receiving 5 mg of prednisone daily and those receiving 5 mg of prednisone twice daily. All-grade hypertension occurred in 39.7% of mCRPC and 47.8% of mCSPC patients (P = 0.33). Thirty-two percent of patients were actively managed by a clinical pharmacist and had an overall trend of reduced hypertension severity after 12 weeks. CONCLUSION AND RELEVANCE: This single-center, retrospective cohort study found that real-world metastatic prostate cancer patients who received AA had substantially higher incidence and severity of hypertension compared with clinical trials regardless of prednisone dose. In patients with mCRPC and mCSPC, the role of prednisone dose in hypertension incidence and severity warrants further investigation. Overall, results indicate the need for closely monitoring hypertension and optimization of anti-hypertensive therapy by multidisciplinary teams in metastatic prostate cancer patients receiving AA.

Co-expression of Twist and Snai1: predictor of poor prognosis and biomarker of treatment resistance in untreated prostate cancer.

BACKGROUND: Prostate cancer (PCa) remains one of the most complex tumors in men. The assessment of gene expression is expected to have a profound impact on cancer diagnosis, prognosis, and treatment decisions. The aim of this study was to determine the utility of the epithelial-mesenchymal transition (EMT) transcription factors Twist and Snai1 in the treatment of naïve prostate cancer. METHODS AND RESULTS: We analyzed formalin-fixed paraffin-embedded (FFPE) prostate tissues from 108 PCa patients and 20 control biopsies using real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and 2-ΔΔCt methods for Twist and Snail gene expression. The expression of Twist and Snai1 mRNA was significantly overexpressed in primary tissues of PCa patients compared with controls using ROC curve. Statistical analysis showed that the mRNAs of these two genes expression Snai1 and Twist were positively correlated with tumor development and prognostic parameters as Gleason score (p < 0.001; r = 0.707) and (p < 0.001; r = 0.627) respectively. The results of Kaplan-Meier analysis showed that mRNA expression of Snai1 and Twist genes expression were significant predictors of poor overall survival (OS) (Log rank p < 0.001) and progression-free survival (PFS) of patients (Log rank p < 0.001). Furthermore, our results showed that the expression of Snai1 and Twist genes expression in primary tissues of PCa patients could predict resistance to androgen deprivation therapy (p < 0.001) and resistance to the acidic drugs abiraterone or enzalutamide (p < 0.001). However, these two transcription factors failed to predict taxanes resistance at the time of diagnosis (p > 0.05). CONCLUSION: These results suggest that Snai1 and Twist are overexpressed during the onset and progression of PCa malignancies and may be theranostic markers of resistance to ADT, abiraterone, or enzalutamide therapy.

Cost-effectiveness and budget impact analysis of enzalutamide in comparison to abiraterone in treatment of metastatic prostate cancer resistant to castration in Iran.

INTRODUCTION: In recent years, enzalutamide and abiraterone have been widely used as treatments for metastatic castration-resistant prostate cancer (mCRPC). However, the cost-effectiveness of these drugs in Iran is unknown. This study evaluated the cost-effectiveness of enzalutamide for the treatment of metastatic prostate cancer resistant to castration in Iran. METHODS: A 3-state Markov model was developed to evaluate the cost-effectiveness of enzalutamide and abiraterone from a social perspective over 10 years. The clinical inputs were obtained from the meta-analysis studies. The direct medical costs were obtained from the tariffs of the healthcare system, while the direct non-medical and indirect costs were collected from the patients. The data of utilities were derived from the literature. In addition, sensitivity analyses were conducted to assess the uncertainties. RESULTS: Compared with Abiraterone, enzalutamide was associated with a high incremental cost-effectiveness ratio (ICER) of $6,260 per QALY gained. According to the one-way sensitivity analysis, ICER was most heavily influenced by the prices of enzalutamide and Abiraterone, non-medical costs, and indirect costs. Regardless of the variation, enzalutamide remained cost-effective. The budget impact analysis of enzalutamide in the health system during 5 years was estimated at $6,362,127. CONCLUSIONS: At current prices, adding enzalutamide to pharmaceutical lists represents the cost-effective use of the healthcare resources in Iran for the treatment of metastatic castration-resistant prostate cancer.

Impact of a pharmacist-led oral chemotherapy monitoring clinic at the South Texas Veterans Health Care System.

As cancer treatments shift from traditional intravenous chemotherapy to inclusion of oral oncolytics, there is a critical need for structured oral chemotherapy monitoring and follow-up programs. To provide continuous care and minimize clinical gaps to Veterans receiving oral chemotherapy, the hematology/oncology clinical pharmacy practitioners designed and initiated a pilot, pharmacist-driven, Oral Chemotherapy Monitoring Clinic at the South Texas Veterans Health Care System supported by an oral chemotherapy certified pharmacy technician. A retrospective evaluation of patients receiving oral chemotherapy at the South Texas Veterans Health Care System was performed before (Phase I) and after (Phase II) pilot implementation to assess the impact of an Oral Chemotherapy Monitoring Clinic on compliance with drug-specific lab and symptom monitoring. Complete monitoring was defined as 100% of recommended labs and symptoms assessed per cycle, partial monitoring was <100%, but >0%, and incomplete monitoring was defined as 0%. The primary outcome assessed the proportion of patients receiving complete monitoring in Phase II compared to Phase I. Most patients were male (94%), with a median age of 72 years. The most common oncolytic was abiraterone acetate. Overall, drug-specific baseline and follow-up laboratory and symptom monitoring was complete at a statistically significantly higher rate in Phase II compared with Phase I (p-value < 0.01). A significantly higher portion of patients in the Phase II cohort had a clinical pharmacy practitioner intervention (44% vs. 90%; p < 0.01). Monitoring for Veterans receiving oral chemotherapy was optimized with clinical pharmacy practitioner and certified pharmacy technician involvement while simultaneously alleviating Oncologist and nurse oral chemotherapy workload.

Hypersensitivity reaction to Abiraterone, successful desensitization protocol in prostate cancer patient.

INTRODUCTION: In prostate cancer, androgens are key in the growth of both normal prostate and cancer cells. Abiraterone acetate inhibits CYP17, an important target in prostate cancer given its central role in the production of adrenal and tumor-derived androgens. Although abiraterone is generally well tolerated, common adverse effects such as hypertension, hypokalemia, and hepatotoxicity have been reported. CLINICAL CASE: We present the case of an 83-year-old Mexican man with high-volume EC IV prostate cancer resistant to castration, orchiectomy, and bone, liver, and lung metastases. First-line treatment with the CHAARTED scheme was indicated, by patient decision refuse chemotherapy treatment. On the fourth day of starting treatment, he developed pruritic erythematous macular skin lesions and urticaria on the posterior chest that resolved spontaneously. A generalized erythematous and pruritic maculopapular rash appeared 12 days after starting abiraterone, for which she was referred to allergies. MANAGEMENT AND RESULTS: An oral provocation test was performed for two days, presenting localized macular lesions eight hours after the administration of abiraterone. An oral desensitization protocol was carried out for ten days in which no hypersensitivity reactions were observed, thus achieving the successful administration of abiraterone.

Long-Term Pharmacokinetic Follow-Up of Abiraterone Acetate in Patients with Metastatic Castration-Resistant Prostate Cancer.

This ABIGENE pharmacokinetic (PK) study sought mainly to characterize the unchanged drug PK during long-term abiraterone acetate (AA) administration in advanced prostate cancer patients (81 patients). It was observed that individual AA concentrations remained constant over treatment time, with no noticeable changes during repeated long-term drug administration for up to 120 days. There was no correlation between AA concentrations and survival outcomes. However, a significant association between higher AA concentrations and better clinical benefit was observed (p = 0.041). The safety data did not correlate with the AA PK data. A significant positive correlation (r = 0.40, p < 0.001) was observed between mean AA concentration and patient age: the older the patient, the higher the AA concentration. Patient age was found to impact steady-state AA concentration: the older the patient, the higher the mean AA concentration. Altogether, these data may help to guide future research and clinical trials in order to maximize the benefits of AA metastatic castration-resistant prostate cancer patients.

Plasma microRNA Signature as Companion Diagnostic for Abiraterone Acetate Treatment in Metastatic Castration-Resistant Prostate Cancer: A Pilot Study.

Abiraterone acetate (AA) serves as a medication for managing persistent testosterone production in patients with metastatic castration-resistant prostate cancer (mCRPC). However, its efficacy varies among individuals; thus, the identification of biomarkers to predict and follow treatment response is required. In this pilot study, we explored the potential of circulating microRNAs (c-miRNAs) to stratify patients based on their responsiveness to AA. We conducted an analysis of plasma samples obtained from a cohort of 33 mCRPC patients before and after three, six, and nine months of AA treatment. Using miRNA RT-qPCR panels for candidate discovery and TaqMan RT-qPCR for validation, we identified promising miRNA signatures. Our investigation indicated that a signature based on miR-103a-3p and miR-378a-5p effectively discriminates between non-responder and responder patients, while also following the drug's efficacy over time. Additionally, through in silico analysis, we identified target genes and transcription factors of the two miRNAs, including PTEN and HOXB13, which are known to play roles in AA resistance in mCRPC. In summary, our study highlights two c-miRNAs as potential companion diagnostics of AA in mCRPC patients, offering novel insights for informed decision-making in the treatment of mCRPC.

Genetic variations predicting progression with docetaxel and novel androgen-receptor pathway inhibitors.

Genetic variations represented by single-nucleotide polymorphisms (SNPs) could be helpful for choosing an effective treatment for patients with prostate cancer. This study investigated the prognostic and predictive values of SNPs associated with the prognoses of pharmacotherapy for prostate cancer through their pharmacological mechanisms. Patients treated with docetaxel or androgen receptor pathway inhibitors (ARPIs), such as abiraterone and enzalutamide, for castration-resistant prostate cancer were included. The SNPs of interest were genotyped for target regions. The prognostic and predictive values of the SNPs for time to progression (TTP) were examined using the Cox hazard proportional model and interaction test, respectively. Rs1045642 in ABCB1, rs1047303 in HSD3B1, rs1856888 in HSD3B1, rs523349 in SRD5A2, and rs34550074 in SLCO2A1 were differentially associated with TTP between docetaxel chemotherapy and ARPI treatment. In addition to rs4775936 in CYP19A1, rs1128503 in ABCB1 and rs1077858 in SLCO2B1 might be differentially associated with TTP between abiraterone and enzalutamide treatments. Genetic predictive models using these SNPs showed a differential prognosis for treatments. This study identified SNPs that could predict progression as well as genetic models that could predict progression when patients were treated with docetaxel versus ARPI and abiraterone versus enzalutamide. The use of genetic predictive models is expected to be beneficial in selecting the appropriate treatment for the individual patient.

Molecular features and race-associated outcomes of SPOP-mutant metastatic castration-resistant prostate cancer.

BACKGROUND: Inactivating alterations in SPOP frequently occur in prostate cancer and promote increased dependency on androgen receptor (AR)-mediated oncogenic signaling. The presence of SPOP mutation (SPOP-mutant [SPOP-mut]) may therefore impact therapeutic outcomes with AR-directed therapies and docetaxel in metastatic castration-resistant (mCRPC). METHODS: This was a retrospective study of mCRPC patients treated at an urban academic hospital (n = 103). Patients underwent tumor DNA sequencing to determine SPOP mutational status (SPOP-mut). Outcomes measured were overall survival (OS) from diagnosis and treatment with second-generation AR signaling inhibitor (ARSI) or docetaxel and time to PSA progression (prostate-specific antigen-progression-free survival [PSA-PFS]) compared by SPOP status using Kaplan-Meier curves and log-rank test. The univariable and multivariable Cox proportional hazard model evaluated the association of SPOP mutation and outcomes adjusted for clinicopathologic features. RESULTS: SPOP-mut was associated with longer PSA-PFS in mCRPC (median 1.79 vs. 0.84 years; p = 0.06) and multivariate analysis (hazard ratio [HR] = 0.37; 95% confidence interval [CI]: 0.17-0.84; p = 0.02). SPOP-mut demonstrated a higher median PSA decline compared to SPOP wild-type (median decline 100% vs. 92%, p = 0.02). SPOP-mut was not associated with OS from the start of ARSI or docetaxel (median OS not reached vs. 2.0 years) or PSA-PFS on docetaxel (median PSA-PFS 0.4 vs. 0.5 years) in mCRPC. The majority of SPOP mutations were identified in African American (AA) patients (69.2%) compared to Caucasian patients (30.8%). Race-associated multivariate analysis revealed no significant differences in OS from the start of ARSI or the start of docetaxel and no differences in ARSI or docetaxel PSA-PFS between AA and Caucasian patients. Molecular profiling demonstrated that AA patients had a higher frequency of SPOP mutations and greater heterogeneity of SPOP variants within the coding sequence. Analysis of concurrent genomic alterations revealed that SPOP mutations co-occur with APC mutations (p = 0.001) and alterations in the Wnt pathway (p = 0.017). CONCLUSIONS: Inactivating mutations in SPOP are associated with better response to ARSI treatment in mCRPC overall. Additional analysis with a larger cohort is needed to evaluate the association of SPOP status and outcomes with docetaxel. Race-associated clinical outcomes and molecular features were observed, suggesting the benefit of biomarker-directed therapy selection for individualized patient subsets in guiding treatment decisions for mCRPC patients.

Dynamic assessment of serum chromogranin A and treatment response with abiraterone acetate in metastatic castration-resistant prostate cancer.

OBJECTIVE: Elevated serum chromogranin A (CGA) is associated with intrinsic or treatment-related neuroendocrine differentiation (NED) in men with metastatic castration-resistant prostate cancer (mCRPC). Fluctuations in serum CGA during treatment of mCRPC have had conflicting results. We analyzed the impact of (i) rising serum CGA and (ii) baseline CGA/PSA ratio during treatment to identify associations with abiraterone acetate (AA) therapy. METHODS: Between June 2013 and August 2015, 92 men with mCRPC were enrolled in a prospective trial with uniform serum CGA processing performed before initiating abiraterone acetate/prednisone (AA/P) and serially after 12 weeks of AA/P treatments. Serum CGA was measured using a homogenous automated immunofluorescent assay. Patients receiving proton pump inhibitors or with abnormal renal function were excluded due to possible false elevations of serum CGA (n = 21 excluded), therefore 71 patients were analyzed. All patients underwent a composite response assessment at 12-weeks. Kaplan-Meier estimates and Cox Regression models were used to calculate the association with time-to-treatment failure analyses and overall survival. RESULTS: An increase in chromogranin was associated with a lower risk of treatment failure (hazard ratio [HR]: 0.52, p = 0.0181). The median CGA/PSA ratio was 7.8 (2.6-16.0) and an elevated pretreatment CGA/PSA ratio above the median was associated with a lower risk of treatment failure (HR: 0.54 p value = 0.0185). An increase in CGA was not found to be associated with OS (HR: 0.71, 95% CI: 0.42-1.21, p = 0.207). An elevated baseline CGA/PSA ratio was not associated with OS (HR: 0.62, 95% CI: 0.37-1.03, p = 0.062). An increase in PSA after 12 weeks of treatment was associated with an increased risk of treatment failure (HR: 4.14, CI: 2.21-7.73, p = < 0.0001) and worse OS (HR: 2.93, CI: 1.57-4.45, p = < 0.0001). CONCLUSIONS: We show that an increasing chromogranin on AA/P and an elevated baseline CGA/PSA in patients with mCRPC were associated with a favorable response to AA/P with no changes in survival. There may be limited clinical utility in serum CGA testing to evaluate for lethal NED as AA/P did not induce lethal NED in this cohort. This highlights that not all patients with an increasing CGA have a worse OS.

Cardiovascular outcomes among patients with castration-resistant prostate cancer: A comparative safety study using US administrative claims data.

BACKGROUND: Cardiovascular conditions are the most prevalent comorbidity among patients with prostate cancer, regardless of treatment. Additionally, cardiovascular risk has been shown to increase following exposure to certain treatments for advanced prostate cancer. There is conflicting evidence on risk of overall and specific cardiovascular outcomes among men treated for metastatic castrate resistant prostate cancer (CRPC). We, therefore, sought to compare incidence of serious cardiovascular events among CRPC patients treated with abiraterone acetate plus predniso(lo)ne (AAP) and enzalutamide (ENZ), the two most widely used CRPC therapies. METHODS: Using US administrative claims data, we selected CRPC patients newly exposed to either treatment after August 31, 2012, with prior androgen deprivation therapy (ADT). We assessed incidence of hospitalization for heart failure (HHF), ischemic stroke, and acute myocardial infarction (AMI) during the period 30-days after AAP or ENZ initiation to discontinuation, outcome occurrence, death, or disenrollment. We matched treatment groups on propensity-scores (PSs) to control for observed confounding to estimate the average treatment effect among the treated (AAP) using conditional Cox proportional hazards models. To account for residual bias, we calibrated our estimates against a distribution of effect estimates from 124 negative-control outcomes. RESULTS: The HHF analysis included 2322 (45.1%) AAP initiators and 2827 (54.9%) ENZ initiators. In this analysis, the median follow-up times among AAP and ENZ initiators (after PS matching) were 144 and 122 days, respectively. The empirically calibrated hazard ratio (HR) estimate for HHF was 2.56 (95% confidence interval [CI]: 1.32, 4.94). Corresponding HRs for AMI and ischemic stroke were 1.94 (95% CI: 0.90, 4.18) and 1.25 (95% CI: 0.54, 2.85), respectively. CONCLUSIONS: Our study sought to quantify risk of HHF, AMI and ischemic stroke among CRPC patients initiating AAP relative to ENZ within a national administrative claims database. Increased risk for HHF among AAP compared to ENZ users was observed. The difference in myocardial infarction did not attain statistical significance after controlling for residual bias, and no differences were noted in ischemic stroke between the two treatments. These findings confirm labeled warnings and precautions for AAP for HHF and contribute to the comparative real-world evidence on AAP relative to ENZ.

Comparison of circulating tumor DNA between African American and Caucasian patients with metastatic castrate-resistant prostate cancer post-abiraterone and/or enzalutamide.

BACKGROUND: African American men are much more likely than Caucasian men to be diagnosed with and to die of prostate cancer. Genetic differences likely play a role. The cBioPortal database reveals that African American men with prostate cancer have higher rates of CDK12 somatic mutations compared to Caucasian men. However, this does not account for prior prostate cancer treatments, which are particularly important in the castrate-resistant setting. We aimed to compare somatic mutations based on circulating tumor DNA (ctDNA) in metastatic castration-resistant prostate cancer (mCRPC) between African American and Caucasian men after exposure to abiraterone and/or enzalutamide. METHODS: This single-institution retrospective study characterizes the somatic mutations detected on ctDNA for African American and Caucasian men with mCRPC who had progressed after abiraterone and/or enzalutamide from 2015 through 2022. We evaluated the gene mutations and types of mutations in this mCRPC cohort. RESULTS: There were 50 African American and 200 Caucasian men with CRPC with available ctDNA data. African American men were younger at the time of diagnosis (p = 0.008) and development of castration resistance (p = 0.006). African American men were more likely than Caucasian men to have pathogenic/likely pathogenic (P/LP) mutations in CDK12 (12% vs. 1.5%; p = 0.003) and copy number amplifications and P/LP mutations in KIT (8.0% vs. 1.5%; p = 0.031). African American men were also significantly more likely to have frameshift mutations (28% vs. 14%; p = 0.035). CONCLUSIONS: Compared to Caucasian men, African American men with mCRPC after exposure to abiraterone and/or enzalutamide had a higher incidence of somatic CDK12 P/LP mutations and KIT amplifications and P/LP mutations based on ctDNA. African American men also had more frameshift mutations. We hypothesize that these findings have potential implications for tumor immunogenicity.

Docetaxel versus abiraterone for metastatic hormone-sensitive prostate cancer with focus on efficacy of sequential therapy.

PURPOSE: We aimed to assess the oncologic efficacy of combining docetaxel (DOC) versus abiraterone (ABI) with androgen deprivation therapy (ADT) in patients with high-risk metastatic hormone-sensitive prostate cancer (mHSPC), with a focus on the efficacy of sequential therapy, in a real-world clinical practice setting. METHODS: The records of 336 patients who harbored de novo high-risk mHSPC, based on the LATITUDE criteria, and had received ADT with either DOC (n = 109) or ABI (n = 227) were retrospectively analyzed. Overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS), including time to castration-resistant prostate cancer (CRPC), time to 2nd-line progression (PFS2), and 2nd- and 3rd-line PFS, were compared. We used one-to-two propensity score matching to minimize the confounders. The differential efficacy of 2nd-line therapy based on agents in each arm was evaluated using the unmatched cohort as an additional interest. RESULTS: After propensity score matching, 86 patients treated with DOC + ADT and 172 with ABI + ADT were available for analyses. The 3-year OS and CSS for DOC versus ABI were 76.2% versus 75.1% (p = 0.8) and 78.2% versus 78.6% (p = 1), respectively. There was no difference in the median PFS2 (49 vs. 43 months, p = 0.39), while the median time to CRPC in patients treated with ABI was significantly longer compared to those treated with DOC (42 vs. 22 months; p = 0.006). The median 2nd-line PFS (14 vs. 4 months, p < 0.001) and 3rd-line PFS (4 vs. 2 months, p = 0.012) were significantly better in the DOC group than in the ABI group. Among the unmatched cohort, after ABI for mHSPC, the median 2nd-line PFS did not differ between the patients treated with DOC and those treated with enzalutamide as 2nd-line therapy (both 3 months, p = 0.8). CONCLUSIONS: ADT with DOC or ABI has comparable oncologic outcomes in terms of OS, CSS, and PFS2 in patients with de novo high-risk mHSPC. Compared to DOC, ABI resulted in longer time to CRPC but worse 2nd and 3rd-line PFS. Further studies are needed to clarify the optimal sequence of therapy in the upfront intensive treatment era.

Clinical outcomes in patients with metastatic castrate-resistant prostate cancer treated with abiraterone with or without ongoing androgen deprivation therapy: A retrospective case-control study.

INTRODUCTION: Abiraterone and concurrent androgen deprivation therapy (ADT) are used in the treatment of patients with metastatic castration-resistant prostate cancer. Recently, it has been suggested that the use of abiraterone alone (without ADT) may have comparable efficacy to abiraterone with ongoing ADT. Here, we sought to assess the impact of ADT cessation in patients beginning abiraterone for castration-resistant prostate cancer. METHODS: We identified 39 patients at our institution who received abiraterone alone (with discontinuation of ADT) between 2011 and 2022. We then procured a comparable group of 39 patients (matched by age, Gleason score, and prostate-specific antigen [PSA] level) who received abiraterone with ongoing ADT during the same period. We assessed and compared clinical outcomes in the two groups (abiraterone-alone vs. abiraterone-ADT) with respect to PSA response rates, PSA progression-free survival, and overall survival. Results were adjusted using Cox proportional-hazards multivariable models. RESULTS: The median PSA before treatment initiation was 12.7 (range: 0.2-199) ng/mL in the abiraterone-alone group and 15.5 (range: 0.6-212) ng/mL in the abiraterone-ADT group. Use of abiraterone alone adequately suppressed testosterone levels in 35/37 (94.6%) patients. Patients receiving abiraterone alone had a median PSA reduction of 80.2% versus 79.5% in patients receiving abiraterone plus ADT. The median PSA progression-free survival in patients receiving abiraterone alone was 27.4 versus 25.8 months in patients receiving abiraterone plus ADT (hazard ratio [HR] 1.10; 95% confidence interval [CI] 0.65-1.71; p = 0.82). In addition, abiraterone alone was associated with an overall survival of 3.6 versus 3.1 years in patients receiving abiraterone plus ADT (HR 0.90; 95% CI 0.50-1.62; p = 0.72). There were no differences in PFS or OS between groups after performing Cox multivariable regression analyses. CONCLUSION: Use of abiraterone alone was associated with comparable clinical outcomes to patients who received abiraterone together with ADT. Further prospective studies are warranted to evaluate the impact of abiraterone alone on treatment outcomes and cost savings.

Niraparib with Abiraterone Acetate and Prednisone for Metastatic Castration-Resistant Prostate Cancer: Phase II QUEST Study Results.

Niraparib (NIRA) is a highly selective inhibitor of poly (adenosine diphosphate-ribose) polymerase, PARP1 and PARP2, which play a role in DNA repair. The phase II QUEST study evaluated NIRA combinations in patients with metastatic castration-resistant prostate cancer who were positive for homologous recombination repair gene alterations and had progressed on 1 prior line of novel androgen receptor-targeted therapy. Results from the combination of NIRA with abiraterone acetate plus prednisone, which disrupts androgen axis signaling through inhibition of CYP17, showed promising efficacy and a manageable safety profile in this patient population.