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The prostate cancer drug abiraterone can be metabolized into several substances with different effects, and optimization of this process could be helpful for fine-tuning the treatment of prostate cancer. Manipulating antitumour activity of abiraterone The anti-androgen prostate cancer drug abiraterone is metabolized in the body to Δ4-abiraterone (D4A), a more potent steroid than abiraterone with structural similarities to endogenous steroidal 5α-reductase substrates, such as testosterone. These authors show that D4A is converted in the body to at least six previously unrecognized metabolites with a range of different metabolic effects. In a clinical trial of abiraterone alone, followed by abiraterone plus the 5α-reductase inhibitor dutasteride, production of a downstream tumour-promoting metabolite was blocked and D4A concentrations rose. These findings suggest a previously unappreciated method of clinically fine-tuning abiraterone metabolism to optimize cancer therapy. Abiraterone blocks androgen synthesis and prolongs survival in patients with castration-resistant prostate cancer, which is otherwise driven by intratumoral androgen synthesis 1 , 2 . Abiraterone is metabolized in patients to Δ 4 -abiraterone (D4A), which has even greater anti-tumour activity and is structurally similar to endogenous steroidal 5α-reductase substrates, such as testosterone 3 . Here, we show that D4A is converted to at least three 5α-reduced and three 5β-reduced metabolites in human serum. The initial 5α-reduced metabolite, 3-keto-5α-abiraterone, is present at higher concentrations than D4A in patients with prostate cancer taking abiraterone, and is an androgen receptor agonist, which promotes prostate cancer progression. In a clinical trial of abiraterone alone, followed by abiraterone plus dutasteride (a 5α-reductase inhibitor), 3-keto-5α-abiraterone and downstream metabolites were depleted by the addition of dutasteride, while D4A concentrations rose, showing that dutasteride effectively blocks production of a tumour-promoting metabolite and permits D4A accumulation. Furthermore, dutasteride did not deplete the three 5β-reduced metabolites, which were also clinically detectable, demonstrating the specific biochemical effects of pharmacological 5α-reductase inhibition on abiraterone metabolism. Our findings suggest a previously unappreciated and biochemically specific method of clinically fine-tuning abiraterone metabolism to optimize therapy.

Abiraterone acetate (AA) is an inhibitor of androgen biosynthesis, though this cannot fully explain its efficacy against androgen-independent prostate cancer. Here, we demonstrate that androgen deprivation therapy depletes androgen-utilizing Corynebacterium spp. in prostate cancer patients and that oral AA further enriches for the health-associated commensal, Akkermansia muciniphila . Functional inferencing elucidates a coinciding increase in bacterial biosynthesis of vitamin K2 (an inhibitor of androgen dependent and independent tumor growth). These results are highly reproducible in a host-free gut model, excluding the possibility of immune involvement. Further investigation reveals that AA is metabolized by bacteria in vitro and that breakdown components selectively impact growth. We conclude that A . muciniphila is a key regulator of AA-mediated restructuring of microbial communities, and that this species may affect treatment response in castrate-resistant cohorts. Ongoing initiatives aimed at modulating the colonic microbiota of cancer patients may consider targeted delivery of poorly absorbed selective bacterial growth agents. Abiraterone acetate (AA) is indicated for the treatment of patients with metastatic castrate-resistant prostate cancer. Here, the authors show that, in prostate cancer patients, orally administered AA remodels the gut microbiome and promotes the enrichment of the commensal bacterium Akkermansia muciniphila at the expense of androgen-utilizing Corynebacterium species.

Novel drugs, drug sequences and combinations have improved the outcome of prostate cancer in recent years. The latest approvals include abiraterone acetate, enzalutamide and apalutamide which target androgen receptor (AR) signaling, radium-223 dichloride for reduction of bone metastases, sipuleucel-T immunotherapy and taxane-based chemotherapy. Adding abiraterone acetate to androgen deprivation therapy (ADT) in order to achieve complete androgen blockade has proven highly beneficial for treatment of locally advanced prostate cancer and metastatic hormone-sensitive prostate cancer (mHSPC). Also, ADT together with docetaxel treatment showed significant benefit in mHSPC. Ongoing clinical trials for different subgroups of prostate cancer patients include the evaluation of the second-generation AR antagonists enzalutamide, apalutamide and darolutamide, of inhibitors of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway, of inhibitors of DNA damage response, of targeted alpha therapy and of prostate-specific membrane antigen (PSMA) targeting approaches. Advanced clinical studies with immune checkpoint inhibitors have shown limited benefits in prostate cancer and more trials are needed to demonstrate efficacy. The identification of improved, personalized treatments will be much supported by the major progress recently made in the molecular characterization of early- and late-stage prostate cancer using “omics” technologies. This has already led to novel classifications of prostate tumors based on gene expression profiles and mutation status, and should greatly help in the choice of novel targeted therapies best tailored to the needs of patients.

The majority of patients with metastatic castration-resistant prostate cancer (mCRPC) will have disease progression of a uniformly fatal disease. mCRPC is driven by both activated androgen receptors and elevated intratumoural androgens; however, the current standard of care is therapy that targets a single androgen signalling mechanism. We aimed to investigate the combination treatment using apalutamide plus abiraterone acetate, each of which suppresses the androgen signalling axis in a different way, versus standard care in mCRPC. ACIS was a randomised, placebo-controlled, double-blind, phase 3 study done at 167 hospitals in 17 countries in the USA, Canada, Mexico, Europe, the Asia-Pacific region, Africa, and South America. We included chemotherapy-naive men (aged ≥18 years) with mCRPC who had not been previously treated with androgen biosynthesis signalling inhibitors and were receiving ongoing androgen deprivation therapy, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and a Brief Pain Inventory-Short Form question 3 (ie, worst pain in the past 24 h) score of 3 or lower. Patients were randomly assigned (1:1) via a centralised interactive web response system with a permuted block randomisation scheme (block size 4) to oral apalutamide 240 mg once daily plus oral abiraterone acetate 1000 mg once daily and oral prednisone 5 mg twice daily (apalutamide plus abiraterone–prednisone group) or placebo plus abiraterone acetate and prednisone (abiraterone–prednisone group), in 28-day treatment cycles. Randomisation was stratified by presence or absence of visceral metastases, ECOG performance status, and geographical region. Patients, the investigators, study team, and the sponsor were masked to group assignments. An independent data-monitoring committee continually monitored data to ensure ongoing patient safety, and reviewed efficacy data. The primary endpoint was radiographic progression-free survival assessed in the intention-to-treat population. Safety was reported for all patients who received at least one dose of study drug. This study is completed and no longer recruiting and is registered with ClinicalTrials.gov, number NCT02257736. 982 men were enrolled and randomly assigned from Dec 10, 2014 to Aug 30, 2016 (492 to apalutamide plus abiraterone–prednisone; 490 to abiraterone–prednisone). At the primary analysis (median follow-up 25·7 months [IQR 23·0–28·9]), median radiographic progression-free survival was 22·6 months (95% CI 19·4–27·4) in the apalutamide plus abiraterone–prednisone group versus 16·6 months (13·9–19·3) in the abiraterone–prednisone group (hazard ratio [HR] 0·69, 95% CI 0·58–0·83; p<0·0001). At the updated analysis (final analysis for overall survival; median follow-up 54·8 months [IQR 51·5–58·4]), median radiographic progression-free survival was 24·0 months (95% CI 19·7–27·5) versus 16·6 months (13·9–19·3; HR 0·70, 95% CI 0·60–0·83; p<0·0001). The most common grade 3–4 treatment-emergent adverse event was hypertension (82 [17%] of 490 patients receiving apalutamide plus abiraterone–prednisone and 49 [10%] of 489 receiving abiraterone–prednisone). Serious treatment-emergent adverse events occurred in 195 (40%) patients receiving apalutamide plus abiraterone–prednisone and 181 (37%) patients receiving abiraterone–prednisone. Drug-related treatment-emergent adverse events with fatal outcomes occurred in three (1%) patients in the apalutamide plus abiraterone–prednisone group (2 pulmonary embolism, 1 cardiac failure) and five (1%) patients in the abiraterone–prednisone group (1 cardiac failure and 1 cardiac arrest, 1 mesenteric arterial occlusion, 1 seizure, and 1 sudden death). Despite the use of an active and established therapy as the comparator, apalutamide plus abiraterone–prednisone improved radiographic progression-free survival. Additional studies to identify subgroups of patients who might benefit the most from combination therapy are needed to further refine the treatment of mCRPC. Janssen Research & Development.

The role of truncated androgen receptor splice variant-7 (AR-V7) in prostate cancer biology is an unresolved question. Is it simply a marker of resistance to 2nd-generation androgen receptor signaling inhibitors (ARSi) like abiraterone acetate (Abi) and enzalutamide (Enza) or a functional driver of lethal resistance via its ligand-independent transcriptional activity? To resolve this question, the correlation between resistance to ARSi and genetic chances and expression of full length AR (AR-FL) vs. AR-V7 were evaluated in a series of independent patient-derived xenografts (PDXs). While all PDXs lack PTEN expression, there is no consistent requirement for mutation in TP53, RB1, BRCA2, PIK3CA, or MSH2, or expression of SOX2 or ERG and ARSi resistance. Elevated expression of AR-FL alone is sufficient for Abi but not Enza resistance, even if AR-FL is gain-of-function (GOF) mutated. Enza resistance is consistently correlated with enhanced AR-V7 expression. In vitro and in vivo growth responses of Abi-/Enza-resistant LNCaP-95 cells in which CRISPR-Cas9 was used to knockout AR-FL or AR-V7 alone or in combination were evaluated. Combining these growth responses with RNAseq analysis demonstrates that both AR-FL- and AR-V7-dependent transcriptional complementation are needed for Abi/Enza resistance.

In the LATITUDE trial, addition of abiraterone acetate plus prednisone to androgen deprivation therapy (ADT) improved overall survival compared with placebos plus ADT in patients with newly diagnosed, high-risk, metastatic castration-naive prostate cancer. Understanding the effects of treatments on patient-reported outcomes (PROs) and health-related quality of life (HRQOL) is important for treatment decisions; therefore we aimed to analyse the effects of ADT plus abiraterone acetate and prednisone versus ADT plus placebos on PROs and HRQOL in patients in the LATITUDE study. In the multicentre, international, randomised, phase 3 LATITUDE trial, eligible patients were aged 18 years or older, had newly diagnosed, high-risk, metastatic castration-naive prostate cancer confirmed by bone scan (bone metastases) or by CT or MRI (visceral, soft tissue, or nodal metastases), and an Eastern Cooperative Oncology Group (ECOG) performance status score of 2 or less. Patients from 235 clinical sites in 34 countries were randomly assigned (1:1) following a country-by-country scheme done by permuted block randomisation (with two blocks) and stratified by the presence of visceral metastasis and ECOG performance status to receive ADT plus 1000 mg oral abiraterone acetate and 5 mg oral prednisone once daily or ADT plus placebos. Selection of ADT, chemical or surgical, was at the investigator's discretion. The co-primary endpoints of the trial, overall survival and radiographic progression-free survival, have been published. PRO data were collected directly on electronic tablet devices at the clinical sites during screening and before any other visit procedure on day 1 of cycles 1–3, monthly during cycles 4–13, and then every 2 months until the end of treatment, by use of the Brief Pain Inventory—Short Form (BPI-SF), Brief Fatigue Inventory (BFI), Functional Assessment of Cancer Therapy Prostate scale (FACT-P), and the EuroQol (EQ-5D-5L) questionnaires. PRO analyses were an exploratory endpoint. Analyses were by intention-to-treat. Results from the first pre-planned interim analysis (Oct 31, 2016), are presented here. This ongoing study is registered with Clinicaltrials.gov, number NCT01715285. Between Feb 12, 2013, and Dec 11, 2014, 1199 patients were randomly assigned: 597 to ADT plus abiraterone acetate and prednisone and 602 to ADT plus placebos. Median follow-up was 30·9 months (IQR 21·2–33·2) in the ADT plus abiraterone acetate and prednisone group versus 29·7 months (1·4–43·5; 16·1–31·3) in the ADT plus placebos group. Median time to worst pain intensity progression assessed by the BPI-SF score was not reached in either group (ADT plus abiraterone acetate and prednisone, not reached [95% CI not reached to not reached]; 25th percentile 11·07 months [95% CI 9·23–18·43]; ADT plus placebos group, not reached [95% CI not reached to not reached]; 25th percentile 5·62 [95% CI 4·63–7·39]; hazard ratio [HR] 0·63 [95% CI 0·52–0·77]; p<0·0001). Median time to worst fatigue intensity was not reached in either the ADT plus abiraterone acetate and prednisone group (not reached [95% CI not reached to not reached]; 25th percentile 18·4 months [95% CI 12·9–27·7]) or the ADT plus placebos group (not reached [95% CI not reached to not reached]; 25th percentile 6·5 months [95% CI 5·6–9·2]; HR 0·65 [95% CI 0·53–0·81], p=0·0001). Median time to deterioration of functional status assessed by the FACT-P total score scale was 12·9 months (95% CI 9·0–16·6) in the ADT plus abiraterone acetate and prednisone group versus 8·3 months (7·4–11·1) in the ADT plus placebos group (HR 0·85 [95% CI 0·74–0·99]; p=0·032). The addition of abiraterone acetate plus prednisone to ADT in patients with newly diagnosed, high-risk metastatic castration-naive prostate cancer improved overall PROs by consistently showing a clinical benefit in the progression of pain, prostate cancer symptoms, fatigue, functional decline, and overall HRQOL. Janssen Research & Development.

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.

Two novel oral drugs that target androgen signaling have recently become available for the treatment of metastatic castration-resistant prostate cancer (mCRPC). Abiraterone acetate inhibits the synthesis of the natural ligands of the androgen receptor, whereas enzalutamide directly inhibits the androgen receptor by several mechanisms. Abiraterone acetate and enzalutamide appear to be equally effective for patients with mCRPC pre- and postchemotherapy. Rational decision making for either one of these drugs is therefore potentially driven by individual patient characteristics. In this review, an overview of the pharmacokinetic characteristics is given for both drugs and potential and proven drug–drug interactions are presented. Additionally, the effect of patient-related factors on drug disposition are summarized and the limited data on the exposure–response relationships are described. The most important pharmacological feature of enzalutamide that needs to be recognized is its capacity to induce several key enzymes in drug metabolism. The potency to cause drug–drug interactions needs to be addressed in patients who are treated with multiple drugs simultaneously. Abiraterone has a much smaller drug–drug interaction potential; however, it is poorly absorbed, which is affected by food intake, and a large interpatient variability in drug exposure is observed. Dose reductions of abiraterone or, alternatively, the selection of enzalutamide, should be considered in patients with hepatic dysfunction. Understanding the pharmacological characteristics and challenges of both drugs could facilitate decision making for either one of the drugs.

Enzalutamide (ENZ) and Abiraterone Acetate (AA) are both first-line treatments for castration-resistant prostate cancer (CRPC). CRPC patients may switch from ENZ to AA or from AA to ENZ, if they do not respond well to the treatment, or experience intolerable side effects. This study examine treatment switching from ENZ to AA or from AA to ENZ, while investigating death as a competing risk. Whether ENZ compared to AA was associated with a longer time to starting oral opioids was also investigated. An active comparator new-user design was used to identify 1406 men diagnosed with CRPC who received ENZ and AA using the Surveillance, Epidemiology, and End Results-Medicare Linked Database from 2012 to 2016. Inverse probability treatment weights (IPTW)-adjusted Fine-Gray competing risk models were used to compare the switching drugs and time-to-first use of oral opioids after initiating ENZ and AA. Most patients (61 %) received AA, while 39 % received ENZ. Overall, ENZ demonstrated a significant reduction in the Sub-distribution Hazard Ratio (SHR) for switching treatment (IPTW-adjusted SHR 0.63; 95 % CI, 0.54–0.73; P < 0.001), indicating a decrease in treatment switching compared to AA. Cumulative incidence curves revealed substantial differences in switching patterns over time (Gray's test, p < 0.001). For time-to-first oral opioid use, the IPTW-adjusted SHR when comparing ENZ to AA was 0.95 (95 % CI, 0.83–1.09; P = 0.48), showing no significant difference between the two groups. Patients who began their treatment with ENZ exhibited a substantially lower hazard of switching to AA when compared to those who started with AA. •Enzalutamide (ENZ) and Abiraterone Acetate (AA) are both first-line treatments for castration-resistant prostate cancer (CRPC).•This study examine treatment switching from ENZ to AA or from AA to ENZ, while investigating death as a competing risk.•We also investigated whether ENZ compared to AA was associated with a longer time to starting oral opioids was also investigated.•Patients who began their treatment with ENZ exhibited a substantially lower hazard of switching to AA when compared to those who started with AA (IPTW- adjusted SHR, 0.63; 95 % CI, 0.54–0.73; P < .001).•Our analysis did not reveal a statistically significant difference in the hazard of initiating oral opioid use between patients who initiated treatment with ENZ and those who began with AA (IPTW- adjusted SHR, 0.95; 95 % CI, 0.83–1.09; P = 0.48).•Our findings indicates that the choice of initial treatment did not have a impact on the timing of oral opioid use in this cohort.

Enzalutamide (ENZ) and abiraterone acetate with prednisone (AAP) represent novel hormonal therapies used in the treatment of metastatic castration-resistant prostate cancer (mCRPC). The aim of the study was to assess the long-term outcome of mCRPC patients treated with ENZ or AAP in real-life clinical practice. The outcomes of 337 mCRPC patients treated with ENZ or AAP were retrospectively analysed. Median radiographic progression-free (rPFS) and overall survival (OS) of patients treated in the first line (pre-chemotherapy) was 13.89 (95% CI=12.40-16.80) and 31.02 (95% CI=24.27-37.44) months vs. 10.97 (95% CI=8.97-14.82) and 26.57 (95% CI=15.97-33.92) months for those treated in the second line (post-chemotherapy). We found inferior survival for patients with synchronous metastases, high Gleason score (GS) and visceral metastases. The efficacy of both ENZ and AAP in mCRPC patients is herein confirmed. Synchronous metastases, high GS and visceral metastases were identified as significant adverse prognostic factors.