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.

Abiraterone in Classic Congenital Adrenal Hyperplasia: Results of Medical Therapy Before Adrenalectomy

We present the case of a 20-year-old woman with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency, with uncontrolled hyperandrogenemia despite supraphysiological glucocorticoid therapy. We used abiraterone acetate, an inhibitor of the 17-hydroxylase/17,20-lyase enzyme, to suppress adrenal androgen synthesis and allow physiological glucocorticoid and mineralocorticoid therapy, as a proof-of-concept, before proceeding to bilateral adrenalectomy. We report the patient's clinical course, the changes in adrenal steroids, and the immunohistochemistry of the adrenals.

New-generation androgen receptor signaling inhibitors (ARSIs) in metastatic hormone-sensitive prostate cancer (mHSPC): pharmacokinetics, drug-drug interactions (DDIs), and clinical impact

INTRODUCTION

The therapeutic scenario of metastatic hormone-sensitive prostate cancer (mHSPC) has dramatically changed in recent years, with the approval of new-generation Androgen Receptor Signaling Inhibitors (ARSIs), in combination with the androgen deprivation therapy (ADT), which was the previous standard of care. Despite showing a similar clinical efficacy, ARSIs, all of which are administered orally, are different in terms of pharmacokinetic and drug-drug interactions (DDIs).

AREAS COVERED

This review covers the main pharmacokinetic characteristics of ARSIs that have been approved for the first-line therapy of mHSPC patients, underlying the differences among these molecules and focusing on the known or possible interactions with other drugs. Full-text articles and abstracts were searched in PubMed.

EXPERT OPINION

Since prostate cancer occurs mainly in older age, comorbidities and the consequent polypharmacy increase the DDI risk in mHSPC patients who are candidates for ARSI. Waiting for new therapeutic options, in the absence of direct comparisons, pharmacokinetic knowledge is essential to guide clinicians in prescribing ARSI in this setting.

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.

Effects of metformin and silodosin as supplementary treatments to abiraterone on human telomerase reverse transcriptase (hTERT) level in metastatic castration-resistant prostate cancer (mCRPC) cells: An in vitro study

The antiproliferative properties of metformin and silodosin have been observed in prostate cancer. Furthermore, it is hypothesized that the molecular pathways related to these drugs may impact the levels of human telomerase reverse transcriptase (hTERT) in prostate cancer cells. The aim of this study was to assess the effect of metformin and silodosin on the levels of hTERT in metastatic castration-resistant prostate cancer (mCRPC) cells. The present study employed an experimental design with a post-test-only control group. This study utilized the PC3 cell line as a model for mCRPC. A viability experiment was conducted using the CCK-8 method to determine the inhibitory concentration (IC50) values of metformin, silodosin, and abiraterone acetate (AA) after a 72-hour incubation period of PC3 cells. In order to investigate the levels of hTERT, PC3 cells were divided into two control groups: a negative control and a standard therapy with AA. Additionally, three experimental combination groups were added: metformin with AA; silodosin with AA; and metformin, silodosin and AA. The level of hTERT was measured using sandwich ELISA technique. The difference in hTERT levels was assessed using ANOVA followed by a post hoc test. The IC50 values for metformin, silodosin, and AA were 17.7 mM, 44.162 mM, and 66.9 μM, respectively. Our data indicated that the combination of metformin with AA and the combination of metformin, silodosin and AA decreased the hTERT levels when compared to control, AA, and silodosin with AA. The administration of metformin resulted in a reduction of hTERT levels in the PC3 cell line, but the impact of silodosin on hTERT levels was not statistically significant compared to AA group.

Prostate cancer management in Southeast Asian countries: a survey of clinical practice patterns

Background

Prostate cancer (PC) has a serious public health impact, and its incidence is rising due to the aging population. There is limited evidence and consensus to guide the management of PC in Southeast Asia (SEA). We present real-world data on clinical practice patterns in SEA for advanced PC care.

Method

A paper-based survey was used to identify clinical practice patterns and obtain consensus among the panelists. The survey included the demographics of the panelists, the use of clinical guidelines, and clinical practice patterns in the management of advanced PC in SEA.

Results

Most panelists (81%) voted prostate-specific antigen (PSA) as the most effective test for early PC diagnosis and risk stratification. Nearly 44% of panelists agreed that prostate-specific membrane antigen positron emission tomography-computed tomography imaging for PC diagnostic and staging information aids local and systemic therapy decisions. The majority of the panel preferred abiraterone acetate (67%) or docetaxel (44%) as first-line therapy for symptomatic mCRPC patients. Abiraterone acetate (50%) is preferred over docetaxel as a first-line treatment in metastatic castration-sensitive prostate cancer patients with high-volume disease. However, the panel did not support the use of abiraterone acetate in non-metastatic castration-resistant prostate cancer (nmCRPC) patients. Apalutamide (75%) is the preferred treatment option for patients with nmCRPC. The cost and availability of modern treatments and technologies are important factors influencing therapeutic decisions. All panelists supported the use of generic versions of approved therapies.

Conclusion

The survey results reflect real-world management of advanced PC in a SEA country. These findings could be used to guide local clinical practices and highlight the financial challenges of modern healthcare.

Concomitant antihypertensive medication and outcome of patients with metastatic castration-resistant prostate cancer receiving enzalutamide or abiraterone acetate

BACKGROUND

The introduction of novel hormonal therapies represented by enzalutamide (ENZ) and abiraterone acetate (ABI) has reached a great progress in the treatment of metastatic castration-resistant prostate cancer (mCRPC). The majority of mCRPC patients are elderly suffering from chronic co-morbidities requiring use of various concomitant medications. In the present study, we focused on impact of concomitant antihypertensive medication on the outcomes of mCRPC patients treated with ENZ or ABI.

METHODS

In total, 300 patients were included and their clinical data were retrospectively analyzed.

RESULTS

Angiotensin-converting enzyme inhibitors (ACEIs) represented the only concomitant medication significantly associated with survival. The median radiographic progression-free survival (rPFS) and overall survival (OS) for patients using ACEIs were 15.5 and 32.3 months compared to 10.7 and 24.0 months for those not using ACEIs (p = 0.0053 and p = 0.0238, respectively). Cox multivariable analysis revealed the use of ACEIs a significant predictive factor for both rPFS (HR = 0.704, p = 0.0364) and OS (HR = 0.592, p = 0.0185).

CONCLUSION

The findings of this study suggest an association between the concomitant use of ACEIs and longer survival of mCRPC patients receiving ENZ or ABI therapy.

Abiraterone-Associated Mineralocorticoid Excess: A Case Report

Abiraterone acetate causes an adrenocorticotropic hormone (ACTH)-mediated mineralocorticoid excess. We present a 77-year-old man with prostate adenocarcinoma who developed signs and symptoms of mineralocorticoid excess while on abiraterone and discuss its pathophysiology and treatment options. The patient developed hypokalemia, metabolic alkalosis, and hypertension, indicative of increased mineralocorticoid activity, confirmed by elevated ACTH, corticosterone, and deoxycorticosterone levels. Abiraterone inhibits cytochrome P450c17 (CYP17A1), thus inhibiting testosterone and cortisol synthesis. Diminished cortisol synthesis, in turn, leads to excessive mineralocorticoid precursor production mediated by ACTH, leading to enhanced sodium absorption and potassium excretion. Abiraterone is often prescribed with low-dose prednisone to suppress ACTH; however, this strategy may not provide physiological glucocorticoid levels, resulting in ACTH-mediated mineralocorticoid excess in some patients. High-dose steroids or mineralocorticoid antagonists may activate mutant androgen receptors in prostate cancer tissue; therefore, amiloride is suggested for managing residual mineralocorticoid activity. This case highlights the importance of being vigilant for the signs and symptoms of mineralocorticoid excess in patients on abiraterone.

Longitudinal assessment of plasma androgen receptor copy number predicts overall survival in subsequent treatment lines in castration-resistant prostate cancer: analysis from a prospective trial

BACKGROUND

Baseline plasma androgen-receptor copy number (AR-CN) is a promising biomarker for metastatic castration-resistant prostate cancer (mCRPC) outcome and treatment response; however, the role of its longitudinal testing is unproven. We aimed to evaluate the prognostic role of AR-CN assessed before subsequent treatment lines in mCRPC patients.

METHODS

A subgroup analysis of a prospective multicenter biomarker trial (IRSTB030) was carried out. Plasma AR-CN status (classified as normal or gain, cut-off value = 2) was assessed with digital PCR before each treatment line.

RESULTS

Forty mCRPC patients receiving sequentially docetaxel, cabazitaxel and an AR signaling inhibitor (abiraterone or enzalutamide) were analyzed. At multivariate analysis, at each assessment overall survival (OS) was independently correlated with AR-CN status [first line: hazard ratio (HR) 4.1 [95% confidence interval (CI) 1.6-10.5]; second line: HR 2.4 (95% CI 1.1-5.3); third line: HR 2.1 (95% CI 1.0-4.3)] and median prostate-specific antigen [first line: HR 4.4 (95% CI 1.8-10.9); second line: HR 3.4 (95% CI 1.6-7.2); third line: HR 2.5 (95% CI 1.2-5.6)]. In the three subsequent assessments, AR-CN status changed from normal to gain in 15 (38%) patients. These patients had longer OS (47 months) compared with patients presenting AR-CN gain from first assessment (36 months), but shorter than those maintaining normal AR-CN (69 months) (P = 0.003).

CONCLUSIONS

Plasma AR-CN correlates with survival not only at baseline (before first treatment), but also in the assessments before the following lines. Interestingly, AR-CN status may change from normal to gain across subsequent treatments in a significant number of cases, identifying a group of patients with intermediate outcomes. Longitudinal assessment of AR-CN status could represent a promising method to capture mCRPC intrinsic heterogeneity and to improve clinical management.

Cortisol as Biomarker for CYP17-Inhibition is Associated with Therapy Outcome of Abiraterone Acetate

BACKGROUND

Abiraterone acetate is an irreversible 17α-hydroxylase/C17, 20-lyase (CYP17) inhibitor approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC) patients. Inhibition of this enzyme leads to low testosterone and cortisol levels in blood. There is growing evidence that clinical efficacy of abiraterone is related to the rate of suppression of serum testosterone. However, quantification of very low levels of circulating testosterone is challenging. We therefore aimed to investigate whether circulating cortisol levels could be used as a surrogate biomarker for CYP17 inhibition in patients with mCRPC treated with abiraterone acetate.

PATIENTS AND METHODS

mCRPC patients treated with abiraterone acetate were included. Abiraterone and cortisol levels were measured with a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS). On treatment cortisol and abiraterone concentrations were related to treatment response and progression free survival.

RESULTS

In total 117 patients were included with a median cortisol concentration of 1.13 ng/ml (range: 0.03 - 82.2) and median abiraterone trough concentration (Cmin) of 10.2 ng/ml (range: 0.58 - 92.1). In the survival analyses, abiraterone Cmin ≥ 8.4 ng/mL and cortisol  < 2.24 ng/mL were associated with a longer prostate-specific antigen (PSA) independent progression-free survival than patients with an abiraterone concentration  ≥ 8.4 ng/mL and a cortisol concentration ≥ 2.24 ng/mL (13.8 months vs. 3.7 months).

CONCLUSION

Our study shows that cortisol is not an independent predictor of abiraterone response in patients with mCRPC, but it is of added value in combination with abiraterone levels, to predict a response on abiraterone.

The Geriatric Nutritional Risk Index Predicts Prognosis in Japanese Patients with LATITUDE High-Risk Metastatic Hormone-Sensitive Prostate Cancer: A Multi-Center Study

Malnutrition is associated with prognosis in cancer. The geriatric nutritional risk index (GNRI), based on the ratio of actual to ideal body weight and also serum albumin level, is a simple screening tool for assessing nutrition. We investigated the GNRI as a prognostic factor for oncological outcomes in patients with high-risk metastatic hormone-sensitive prostate cancer (mHSPC) using a Japanese multicenter cohort. This study included a total of 175 patients with LATITUDE high-risk mHSPC, of whom 102 had received androgen deprivation therapy (ADT) plus upfront abiraterone acetate, and 73 had received ADT plus bicalutamide (Bica), from 14 institutions associated with the Tokai Urologic Oncology Research Seminar. Patients were classified into GNRI-low (<98) or GNRI-high (≥98) groups. The GNRI was based on the body mass index and serum albumin level. Kaplan-Meier analysis revealed that the median overall survival (OS) of a GNRI-low group (median 33.7 months; 95% confidence interval [CI]: 26.2-not reached [NR]) was significantly worse than that of a GNRI-high group (median: NR; 95% CI: NR-NR; p < 0.001). Multivariate analysis identified Bica and low GNRI (<98) as independent prognostic factors for reduced times to both castration-resistant prostate cancer and OS, and, therefore, a poor prognosis. Our findings indicate the GNRI may be a practical prognostic indicator in the evaluation of survival outcomes in patients with LATITUDE high-risk mHSPC.

Real-world survival outcome comparing abiraterone acetate plus prednisone and enzalutamide for nonmetastatic castration-resistant prostate cancer

BACKGROUND

There is little evidence of abiraterone acetate (AA) plus prednisone for patients with non-metastatic castration-resistant prostate cancer (nmCRPC). In this study, we conducted a comparative analysis of real-world survival outcomes between AA plus prednisone and enzalutamide (Enz) in patients with nmCRPC, utilizing our consortium dataset.

MATERIALS AND METHODS

The clinical records of 133 nmCRPC patients treated with first-line Enz or AA plus prednisone were analyzed. The primary endpoints of the study were overall survival (OS) and cancer-specific survival (CSS). Cumulative incidence function (CIF) using Fine and Gray models was also utilized to assess non-cancer-caused death considering the competing risk of cancer-caused death.

RESULTS

During a median follow-up of 36 months, 34 patients (25.6%) had deceased, with a median OS of 99 months in the entire cohort. There were no significant differences in comorbidities between the Enz and AA groups. Time to PSA progression (TTPP: HR 0.81, 95% CI 0.51-1.30, P = 0.375) and CSS (HR 1.32, 95% CI 0.55-3.44, P = 0.5141) were comparable between the two groups. However, intriguingly, there was a trend towards shorter OS in patients treated with AA plus prednisone compared to Enz (HR 0.57, 95% CI 0.29-1.12, P = 0.0978, median of 99 and 69 months in Enz and AA groups, respectively). CIF analysis revealed that nmCRPC patients treated with AA plus prednisone were more likely to result in non-cancer-caused death than those treated with Enz (HR 5.22, 95% CI 1.88-14.50, P = 0.0014).

CONCLUSIONS

Our real-world survival analysis suggests that while AA plus prednisone may demonstrate comparable treatment efficacy to Enz in the context of nmCRPC, there may be an increased risk of non-cancer-caused death. Physicians should take into consideration this information when making treatment decisions for patients with nmCRPC.

A new method to quantify the effect of co-medication on the efficacy of abiraterone in metastatic castration-resistant prostate cancer patients

Background and Objective: Patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone acetate (AA) have co-morbidities treated with different drugs. The aim was to quantify the potential effect of co-medications on AA treatment duration (TD) and overall survival (OS). Methods: A new parameter, called "individual drug score" (IDS) was calculated by summing the "drug score"-s (DS) of all co-medications for each patient. The DS was determined by quantifying the effect of a given co-drug on enzymes involved in steroidogenesis and metabolism of AA. The correlation between log (IDS) and TD was tested by non-linear curve fit. Kaplan-Meier method and multivariate Cox regression was used for analysis of TD and OS. Results: The IDS and TD of AA+prednisolone showed a dose-response correlation (n = 166). Patients with high IDS had significantly longer TD and OS (p <0.001). In multivariate analysis IDS proved to be an independent marker of TD and OS. The same analysis was performed in a separate group of 81 patients receiving AA+dexamethasone treatment. The previously observed relationships were observed again between IDS and TD or OS. After combining the AA+prednisolone and AA+dexamethasone groups, analysis of the IDS composition showed that patients in the high IDS group not only used more drugs (p <0.001), but their drugs also had a higher mean DS (p = 0.001). Conclusion: The more co-drugs with high DS, the longer the duration of AA treatment and OS, emphasizing the need for careful co-medication planning in patients with mCRPC treated with AA. It is recommended that, where possible, co-medication should be modified to minimize the number of drugs with negative DS and increase the number of drugs with high DS. Our new model can presumably be adapted to other drugs and other cancer types (or other diseases).

Niraparib plus abiraterone acetate with prednisone in patients with metastatic castration-resistant prostate cancer and homologous recombination repair gene alterations: second interim analysis of the randomized phase III MAGNITUDE trial

BACKGROUND

Patients with metastatic castration-resistant prostate cancer (mCRPC) and BRCA alterations have poor outcomes. MAGNITUDE found patients with homologous recombination repair gene alterations (HRR+), particularly BRCA1/2, benefit from first-line therapy with niraparib plus abiraterone acetate and prednisone (AAP). Here we report longer follow-up from the second prespecified interim analysis (IA2).

PATIENTS AND METHODS

Patients with mCRPC were prospectively identified as HRR+ with/without BRCA1/2 alterations and randomized 1 : 1 to niraparib (200 mg orally) plus AAP (1000 mg/10 mg orally) or placebo plus AAP. At IA2, secondary endpoints [time to symptomatic progression, time to initiation of cytotoxic chemotherapy, overall survival (OS)] were assessed.

RESULTS

Overall, 212 HRR+ patients received niraparib plus AAP (BRCA1/2 subgroup, n = 113). At IA2 with 24.8 months of median follow-up in the BRCA1/2 subgroup, niraparib plus AAP significantly prolonged radiographic progression-free survival {rPFS; blinded independent central review; median rPFS 19.5 versus 10.9 months; hazard ratio (HR) = 0.55 [95% confidence interval (CI) 0.39-0.78]; nominal P = 0.0007} consistent with the first prespecified interim analysis. rPFS was also prolonged in the total HRR+ population [HR = 0.76 (95% CI 0.60-0.97); nominal P = 0.0280; median follow-up 26.8 months]. Improvements in time to symptomatic progression and time to initiation of cytotoxic chemotherapy were observed with niraparib plus AAP. In the BRCA1/2 subgroup, the analysis of OS with niraparib plus AAP demonstrated an HR of 0.88 (95% CI 0.58-1.34; nominal P = 0.5505); the prespecified inverse probability censoring weighting analysis of OS, accounting for imbalances in subsequent use of poly adenosine diphosphate-ribose polymerase inhibitors and other life-prolonging therapies, demonstrated an HR of 0.54 (95% CI 0.33-0.90; nominal P = 0.0181). No new safety signals were observed.

CONCLUSIONS

MAGNITUDE, enrolling the largest BRCA1/2 cohort in first-line mCRPC to date, demonstrated improved rPFS and other clinically relevant outcomes with niraparib plus AAP in patients with BRCA1/2-altered mCRPC, emphasizing the importance of identifying this molecular subset of patients.

Plasmatic MicroRNAs and Treatment Outcomes of Patients with Metastatic Castration-Resistant Prostate Cancer: A Hospital-Based Cohort Study and In Silico Analysis

Prostate cancer (PCa) is one of the most common malignancies among men worldwide. Inevitably, all advanced PCa patients develop metastatic castration-resistant prostate cancer (mCRPC), an aggressive phase of the disease. Treating mCRPC is challenging, and prognostic tools are needed for disease management. MicroRNA (miRNA) deregulation has been reported in PCa, constituting potential non-invasive prognostic biomarkers. As such, this study aimed to evaluate the prognostic potential of nine miRNAs in the liquid biopsies (plasma) of mCRPC patients treated with second-generation androgen receptor axis-targeted (ARAT) agents, abiraterone acetate (AbA) and enzalutamide (ENZ). Low expression levels of miR-16-5p and miR-145-5p in mCRPC patients treated with AbA were significantly associated with lower progression-free survival (PFS). The two miRNAs were the only predictors of the risk of disease progression in AbA-stratified analyses. Low miR-20a-5p levels in mCRPC patients with Gleason scores of <8 were associated with worse overall survival (OS). The transcript seems to predict the risk of death regardless of the ARAT agent. According to the in silico analyses, miR-16-5p, miR-145-5p, and miR-20a-5p seem to be implicated in several processes, namely, cell cycle, proliferation, migration, survival, metabolism, and angiogenesis, suggesting an epigenetic mechanism related to treatment outcome. These miRNAs may represent attractive prognostic tools to be used in mCRPC management, as well as a step further in the identification of new potential therapeutic targets, to use in combination with ARAT for an improved treatment outcome. Despite the promising results, real-world validation is necessary.

Trends in the Use of Second-Generation Androgen Receptor Axis Inhibitors for Metastatic Hormone-Sensitive Prostate Cancer and Clinical Factors Predicting Biological Recurrence

The advent of second-generation androgen receptor axis-targeted agents (ARATs) has revolutionized the treatment of metastatic hormone-sensitive prostate cancer (mHSPC). Biochemical recurrence-free survival (BRFS) was used to compare the efficacy of each ARAT. This multicenter retrospective study included 581 patients with newly diagnosed mHSPC who received first-line hormone therapy. The characteristics of patients treated with different ARATs were compared as well as changes in the usage of each drug over time. For BRFS, the apalutamide (Apa) and enzalutamide (Enza) groups, as well as the abiraterone acetate (Abi) and Apa/Enza groups, were compared. In addition, multivariate analysis was performed to determine predictive factors for biochemical recurrence (BCR). The use of second-generation ARATs tended to increase after May 2020. No significant difference in BRFS was found between patients receiving Apa and Enza (p = 0.490) and those receiving Abi or Apa/Enza (p = 0.906). Multivariate analysis revealed that the neutrophil-to-lymphocyte ratio (NLR) ≥ 2.76 and PSA ≥ 0.550 ng/mL were independent predictors of BCR. There were no significant differences in patient characteristics or BRFS in patients with mHSPC receiving different ARATs as first-line treatment. NLR and PSA may be prognostic factors following the first-line treatment of patients with mHSPC.

Effects of In-office Dispensing by Single-specialty Urology Practices on Management of Advanced Prostate Cancer

INTRODUCTION

We examine changes in the volume of patients with advanced prostate cancer and prescriptions for abiraterone and enzalutamide among urology practices with and without in-office dispensing.

METHODS

Using data from the National Council for Prescription Drug Programs, we identified in-office dispensing by single-specialty urology practices from 2011 to 2018. As the greatest growth in implementing dispensing occurred among large groups in 2015, outcomes were measured at the practice level in 2014 (before) and 2016 (after) for dispensing and non-dispensing practices. Outcomes included the volume of men with advanced prostate cancer managed by a practice and prescriptions for abiraterone and/or enzalutamide. Using national Medicare data, generalized linear mixed models were fit to compare the practice-level ratio of each outcome (2016 relative to 2014) adjusting for regional contextual factors.

RESULTS

In-office dispensing increased from 1% to 30% of single-specialty urology practices from 2011 to 2018, with 28 practices implementing dispensing in 2015. In 2016 compared to 2014, adjusted changes in the volume of patients with advanced prostate cancer managed by a practice were similar between non-dispensing (0.88, 95% CI 0.81-0.94) and dispensing (0.93, 95% CI 0.76-1.09) practices (P = .60). Prescriptions for abiraterone and/or enzalutamide increased in both non-dispensing (2.00, 95% CI 1.58-2.41) and dispensing (8.99, 95% CI 4.51-13.47) practices (P < .01).

CONCLUSIONS

In-office dispensing is increasingly common in urology practices. This emerging model is not associated with changes in patient volume but is associated with increased prescriptions for abiraterone and enzalutamide.

Adapting to hormone-therapy resistance for adopting the right therapeutic strategy in advanced prostate cancer

INTRODUCTION

The androgen/androgen receptor (AR) axis represents a key driver of treatment resistance in prostate cancer (PCa) patients receiving androgen deprivation therapy (ADT) and targeted agents, and a deeper comprehension of resistance mechanisms is fundamental to adopt effective therapeutic strategies.

AREAS COVERED

We review the mechanisms of primary or secondary resistance to hormone therapy (HT) in PCa, especially focusing on available data and emerging evidence.

EXPERT OPINION

First- and second-generation HT resistance has been associated with several AR-dependent and AR-independent mechanisms, ranging from the amplification of the AR gene locus to somatic AR mutations and the intratumoral synthesis of androgens from adrenal steroids and cholesterol. As reported in the current review, the development of novel and effective treatments is needed to personalize anticancer therapies in this setting and to finally improve clinical outcomes in patients with HT resistant disease.

Visceral Metastasis Predicts Response to New Hormonal Agents in Metastatic Castration-Sensitive Prostate Cancer

Visceral metastasis (VM) and a higher number of bone metastasis generally define high volume/risk in patients with metastatic castration-sensitive prostate cancer (mCSPC). Subgroup analysis of pivotal trials did not show a clear benefit of second-generation non-steroidal anti-androgens (NSAAs) in patients with VM. However, subgroup analysis of the trial assessing abiraterone acetate, a CYP 17 inhibitor, plus prednisone (AAP) showed an improved overall survival (OS) in patients with mCSPC with VM. We searched MEDLINE, Web of Science, and congress abstracts for the phase III randomized controlled trials of second-generation NSAAs and AAP in patients with mCSPC. In this pooled analysis, we included 6485 patients from the 6 phase III trials. The rate of patients with VM was 15.2%. Interestingly, in contrast to NSAAs, AAP seems to be effective in improving OS among patients with VM (hazard ratio, HR: 0.89, 95% CI, 0.72-1.11, P = .30 for second-generation NSAAs; HR: 0.58, 95% CI, 0.40-0.84, P = .004 for AAP). In contrast, both second-generation NSAAs (HR: 0.63, 95% CI, 0.57-0.70, P < .001) and AAP (HR: 0.68, 95% CI, 0.57-0.81, P < .001) improved OS in patients without VM. In this pooled analysis, we demonstrate that while AAP provided an OS improvement in patients with VM, second-generation NSAAs did not demonstrate a similar OS benefit in this population.

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.

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.

Clinical outcomes of volume of disease on patients receiving enzalutamide versus abiraterone acetate plus prednisone as first-line therapy for metastatic castration-resistant prostate cancer

Background

Androgen receptor signaling inhibitors (ARSis) abiraterone acetate (AA) plus prednisone and enzalutamide (Enza), are currently the most administered first-line treatments for metastatic castration-resistant prostate cancer (mCRPC). AA and Enza have shown similar overall survival (OS) benefits and there is no consensus upon the best option for mCRPC first-line treatment. Volume of disease may represent a useful biomarker to predict response to therapy in such patients.

Objectives

In this study, we seek to evaluate the impact of volume of disease on patients treated with first-line AA versus Enza for mCRPC.

Design and methods

We retrospectively evaluated a cohort of consecutive patients with mCRPC categorized by volume of disease [high volume (HV) or low volume (LV) per E3805 criteria] at ARSi onset and treatment type (AA or Enza), assessing OS and radiographic progression-free survival (rPFS), from therapy start, as co-primary endpoints.

Results

Of the 420 patients selected, 170 (40.5%) had LV and received AA (LV/AA), 76 (18.1%) LV and had Enza (LV/Enza), 124 (29.5%) HV and were given AA (HV/AA), and 50 (11.9%) HV and received Enza (HV/Enza). Among patients with LV, OS was significantly longer when treated with Enza [57.2 months; 95% confidence interval (CI): 52.1-62.2 months] versus AA (51.6 months; 95% CI, 42.6-60.6 months; p = 0.003). Consistently, those with LV receiving Enza showed increased rPFS (40.3 months; 95 CI, 25.0-55.7 months) than those having AA (22.0 months; 95% CI, 18.1-26.0 months; p = 0.004). No significant difference in OS or rPFS was observed in those with HV treated with AA versus Enza (p = 0.51 and p = 0.73, respectively). In multivariate analysis of patients with LV, treatment with Enza was independently associated with better prognosis than AA.

Conclusion

Within the intrinsic limitations of a retrospective design and small population, our report suggests that volume of disease could be a useful predictive biomarker for patients starting first-line ARSi for mCRPC.

Abigene, a Prospective, Multicentric Study of Abiraterone Acetate Pharmacogenetics in Metastatic Castration-Resistant Prostate Cancer

Abiraterone acetate (AA) is the first-in-class of drugs belonging to the second-generation of agents inhibiting androgen neosynthesis in advanced prostate cancer. A cumulative experience attests that germinal gene polymorphisms may play a role in the prediction of anticancer agent pharmacodynamics variability. In the present prospective, multicentric study, gene polymorphisms of CYP17A1 (AA direct target) and the androgen transporter genes SLCO2B1 and SLCO1B3 (potential modulators of AA activity) were confronted with AA pharmacodynamics (treatment response and toxicity) in a group of 137 advanced prostate cancer patients treated in the first line by AA. The median follow-up was 56.3 months (95% CI [52.5-61]). From multivariate analysis, rs2486758 C/C (CYP17A1) and PSA (≥10 ng/mL) were associated with a shorter 3-year biological PFS (HR = 4.05, IC95% [1.46-11.22]; p = 0.007 and HR = 2.08, IC95% [1.31-3.30]; p = 0.002, respectively). From a multivariate analysis, the rs743572 (CYP17A1) and performance status were independently associated with significant toxicity (OR = 3.78 (IC95% [1.42-9.75]; p = 0.006 and OR = 4.54; IC95% [1.46-13.61]; p = 0.007, respectively). Host genome characteristics may help to predict AA treatment efficacy and identify patients at risk for toxicity.