Abiraterone Acetate Treatment Research Articles

The prognostic value of ductal adenocarcinoma of the prostate in patients with advanced prostate cancer treated with abiraterone acetate.

167 Background: Previous studies have indicated that ductal adenocarcinoma of the prostate (DA) is associated with adverse prognosis in patients with localized prostate cancer (PCa). However, the clinical significance of DA in advanced PCa remains largely ambiguous. This study endeavors to investigate the relationship between the existence of DA in prostate biopsy specimens and treatment outcomes among patients with advanced PCa receiving abiraterone acetate (AA) therapy. Methods: We retrospectively analyzed data from 440 patients with advanced PCa who received AA at either the metastatic hormone-sensitive (mHSPC, N=123) or castration-resistant PCa (mCRPC, N=317) stage. The presence of DA and its proportion was evaluated based on prostate biopsy specimens. Kaplan-Meier curves and COX regression were used to evaluate the predictive significance of DA on AA efficacy, including PSA response, PSA progression-free survival (PSA-PFS), and radiographic progression-free survival (rPFS). Results: In aggregate, DA was detected in 35/440 (8.0%) patients, with 13/440 (3.0%) and 22/440 (5.0%) men harboring DA<5% and ≥5%, respectively, in the total tumors. The overall PSA response rate in the entire cohort was 302/440 (68.6%), and it was comparable for people with and without DA, with both groups having a response rate of 68.6%. Of note, compared with patients without DA, men with DA have significantly longer median PSA-PFS (mPSA-PFS, 12.1- vs. 25.0-Mo, P=0.005) and median rPFS (mrPFS, 19.8 vs. 38.2-Mo, P=0.034). Subgroup analysis based on DA proportion further revealed that in comparison with PCa without DA, DA≥5% was an indicator of favorable PSA-PFS (HR, 95%CI: 0.28, 0.14-0.56, p<0.001) and rPFS (HR, 95%CI: 0.35, 0.18-0.72, p=0.004), while DA<5% was not. In multivariate COX regression analysis, after adjusting by clinicopathological factors, including mCRPC/mHSPC stage, ISUP grading, metastatic burden, pain score and pretreatment hemoglobin, alkaline phosphatase, and lactate dehydrogenase, DA≥5% was still independently associated with better therapeutic efficacy of AA treatment (PSA-PFS: HR, 95%CI: 0.36, 0.17-0.74, p<0.001; rPFS: HR, 95%CI: 0.47, 0.23-0.96, p=0.040). Conclusions: A DA proportion ≥5% in the tumor is related to improved treatment efficacy for individuals with advanced PCa receiving AA. Thus, in the pathological diagnosis of PCa, it is necessary to routinely report the presence and proportion of DA in order to aid with treatment decision-making.

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).

Real-life data of abiraterone acetate and enzalutamide treatment in post-chemotherapy metastatic castration-resistant prostate cancer in Poland.

Abiraterone acetate (ABI) and Enzalutamide (ENZA) are second-generation hormone drugs that show breakthrough activity in post-chemotherapy, metastatic castration-resistant prostate cancer (mCRPC). The leading oncological and urological guidelines indicate both drugs with the same strong recommendation. There is a lack of randomized trials which compare the efficacy of ABI and ENZA. The current study aimed to compare the effectiveness of the drugs with an analysis of prognostic factors related to those drugs. The study included 420 patients with docetaxel (DXL) pretreated mCRPC from seven Polish cancer centers. Patients were treated according to inclusion and exclusion criteria in the Polish national drug program (1000 mg ABI and 10 mg prednisone, n=76.2%; ENZA, 160 mg; n=23.8%). The study retrospectively analyzed the overall survival (OS), time to treatment failure (TTF), PSA 50% decline rate (PSA 50%) and selected clinic-pathological data. In the study group, the median OS was 17 months (95% CI: 15.6-18.3). The median OS (26.1 vs. 15.7 mo.; p<0.001), TTF (14.2 vs. 7.6 mo.; p<0.001) and PSA 50% (87.5 vs. 56%; p<0.001) were higher in ENZA than in ABI treatment. Multivariate analysis shows that ENZA treatment and PSA nadir <17.35 ng/mL during or after DXL treatment were related to longer TTF. ENZA treatment, DXL dose ≥750 mg, PSA nadir <17.35 ng/mL during or after DXL treatment was related to longer OS. ENZA treatment may be related to more favorable oncological outcomes than ABI treatment in the studied Polish population of patients. A 50% decline in PSA is an indicator of longer TTF and OS. Due to the non-randomized and retrospective nature of the analysis, the current results require prospective validation.

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.

Body composition parameters were associated with response to abiraterone acetate and prognosis in patients with metastatic castration-resistant prostate cancer.

To investigate the predictive value of body composition parameters for biochemical response to abiraterone acetate (AA) in metastatic castration-resistant prostate cancer (mCRPC) patients with prior chemohormonal therapy. We retrospectively evaluated the clinicopathologic information of 132 mCRPC cases receiving AA treatment after chemohormonal therapy at hormone-sensitive stage from July 2018 to June 2021. All patients were divided into AA responders and non-responders according to the biochemical response to AA (prostate-specific antigen (PSA) reduction ≥50% than pretreatment). Multivariate Logistic analysis was used to determine the independent predictors and develop predictive model of biochemical response to AA. Cox regression analysis was utilized to investigate the prognostic factors for time to biochemical progression (TTBP), radiological progression-free survival (rPFS), failure-free survival (FFS), and overall survival (OS) after AA treatment. There were 57 AA responders and 75 AA non-responders. Periprostatic fat area/prostate area (PPFA/PA) was decreased and skeletal muscle index (SMI) was increased in AA responders compared with AA non-responders. Multivariable logistic analysis demonstrated that ADT duration ≥12 months, bone metastasis only, high SMI and low PPFA/PA were independent predictors of biochemical response to AA treatment. The FFS, TTBP, rPFS, and OS of patients with lower SMI or higher PPFA/PA was decreased compared with that of patients with higher SMI or lower PPFA/PA, respectively. Combining SMI, PPFA/PA, ADT duration and metastatic sites performed well in differentiating AA responders from non-responders. High SMI and low PPFA/PA could predict biochemical response to AA treatment and preferable prognosis in mCRPC patients with prior chemohormonal therapy at hormone-sensitive stage.

Low TLR and PSMA-TV predict biochemical response to abiraterone acetate in metastatic prostate cancer patients developing castration resistance after chemohormonal therapy at hormone-sensitive stage.

To explore whether 68Ga-PSMA-11 PET/CT-derived parameters could predict biochemical response to abiraterone acetate (AA) treatment and prognosis in metastatic prostate cancer patients developing castration resistance after chemohormonal therapy at hormone-sensitive stage. The clinicopathologic data of 106 mCRPC cases receiving AA treatment were retrospectively analyzed. Logistic regression analysis was used to determine the independent predictors of biochemical response to AA treatment. Cox analyses were applied to investigate the independent prognostic factors for time to biochemical progression (TTBP) and radiological progression-free survival (rPFS). Survival analysis and ROC curve were also used. Multivariable Logistic analysis demonstrated that prior ADT duration ≥ 12months, low prostate specific membrane antigen receptor-expressing tumor volume (PSMA-TV), low tumor to liver ratio (TLR) were independent predictors of biochemical response to AA treatment. Multivariate Cox analysis demonstrated that low PSMA-TV and low TLR were independent prognostic factors of longer TTBP and rPFS. The TTBP and rPFS of patients with higher PSMA-TV or TLR were significantly decreased compared with that of patients with lower PSMA-TV and TLR. The area under ROC curve (AUC) of combining ADT duration, PSMA-TV and TLR was 0.82 for predicting biochemical response to AA, which was significantly increased compared with that of other 68Ga-PSMA-11 PET/CT-derived parameters alone. Low PSMA-TV, low TLR were vital independent predictors of biochemical response to AA treatment and were associated with preferable prognosis in mCRPC patients. Combining ADT duration, PSMA-TV and TLR performed well in distinguishing AA responders from non-responders in mCRPC patients.

Predictive factors for the efficacy of abiraterone acetate therapy in high-risk metastatic hormone-sensitive prostate cancer patients.

There is a discrepancy in the efficacy of abiraterone acetate for overall survival (OS) in patients with high-risk metastatic hormone-sensitive prostate cancer (mHSPC). This study aimed to identify predictive factors for the efficacy of abiraterone acetate for OS in high-risk mHSPC patients by analyzing them over a longer observation period. Five hundred high-risk mHSPC patients were retrospectively identified at our hospital and affiliated hospitals in the Kindai Oncology Study Group and Kyoto Prefectural University of Medicine Oncology StudyGroup between December 2013 and March 2022. Two hundred patients were treated with abiraterone acetate (1000mg/day) plus prednisolone (5mg/day) combined with androgen deprivation therapy (ADT). A total of 300 patients were treated with bicalutamide (80mg/day) in combination with ADT. OS was not significantly different between the two treatments in the overall cohort (p = 0.1643). In the subgroup without Gleason pattern 5 at the primary lesion, OS was significantly better in patients treated with abiraterone acetate than in those treated with bicalutamide (p = 0.0192). In the subgroup with Gleason pattern 5 at the primary lesion, no significant difference was found between the two treatments (p = 0.1799). Univariate and multivariate analyses in the subgroup without Gleason pattern 5 at the primary lesion suggested that abiraterone therapy may be an important and independent predictor of OS in high-risk mHSPC patients. The presence of Gleason pattern 5 at the primary lesion may be a predictor for high-risk mHSPC patients who could benefit from abiraterone acetate treatment.

OR12-1 Activity of Abiraterone Acetate in the management of Cushing syndrome associated to advanced adrenocortical carcinoma: results of the ABACUS trial.

Abstract Background More than 50% of adrenocortical carcinomas (ACC) in adults are associated with cortisol excess that makes tumor management challenging and has a negative impact on patient outcome. Abiraterone acetate (AA) is an irreversible inhibitor of the 17α-hydroxylase/C17, 20-lyase (CYP17 enzyme) that is used in patients with prostate cancer, in whom it leads to suppression of cortisol and androgens. Thus, the drug is potentially useful in the medical treatment of steroid-secreting tumors. The aim of this study was to assess the activity of AA to control cortisol excess in patients with advanced ACC and overt Cushing syndrome. Methods We designed the phase II trial ABACUS (NCT 03145285) whose primary endpoint was normalization of 24-h urinary free cortisol (UFC) excretion within 1 month from treatment start. Inclusion criteria were histologically proven ACC, locally advanced or metastatic disease, and Cushing syndrome confirmed by two 24-h UFC &amp;gt;1.5 times the upper normal limit with suppressed ACTH. No concomitant treatment with mitotane or chemotherapy was allowed for the first 4 weeks of the study. AA was given orally at the daily dose of 1000 mg. Results From 2017 to 2019, we included 17 patients with ACC (2 stage III, 15 stage IV), 13 women (76%), median age 51 years (18-76), of whom 8 have been heavily pretreated and 9 were treatment naïve. In 8 patients, multiple steroid secretion was found. Patients were treated with AA for a median of 17 days (7-163). Median 24-h UFC (measured by gas-mass spectrometry) was 368 μg/24h (121-7422) at baseline and 94 μg/24h (20-1793) at end of treatment (p=0.01). Normalization of 24-h UFC was attained in 8 patients (53%) and a &amp;gt;50% decrement in 11 patients (73%). The median time to effect was 21 days and median 24-h UFC reduction 81.8% (-97.7 - +25.9). Androgen and precursor steroids were also significantly reduced by AA treatment. The median Cushing Syndrome Score was 5.0 (2 - 8) at baseline and 3.5 (1 - 6) at the end of treatment, thus confirming clinical improvement. Blood pressure was significantly reduced and hypokalemia was not observed. In 2 patients, treatment was discontinued for toxicity. Seven patients died of ACC progression during follow-up with an overall survival of 5.4 months (0.5-39.3). Conclusions AA was able to control rapidly cortisol excess in most patients with a good safety profile. The results of this proof-of-concept study show that AA looks promising and may be viewed as an additional weapon to manage Cushing syndrome in patients with ACC. These findings pose the basis for power calculation and implementation of a prospective long-term study to establish AA efficacy in patients with a steroid-secreting ACC. Presentation: Sunday, June 12, 2022 11:00 a.m. - 11:15 a.m.

SC98 - A prospective observational study of patients with metastatic castration-resistant prostate cancer progressing after standard hormonal therapy suitable for abiraterone acetate plus prednisone treatment

SC98 - A prospective observational study of patients with metastatic castration-resistant prostate cancer progressing after standard hormonal therapy suitable for abiraterone acetate plus prednisone treatment

Serum prolactin level as a predictive factor for abiraterone response in patients with metastatic castration-resistant prostate cancer.

To investigate the prognostic value and potential therapeutic target of the baseline serum hormones in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone. This retrospective study was performed in patients with mCRPC receiving abiraterone acetate (AA) from July 2016 to September 2020. Patients who had serum hormone tests within 2 weeks before AA treatment were included. Univariate analysis and Cox regression were performed to evaluate the correlation of sex hormones with progression-free survival (PFS) and overall survival (OS). Prolactin (PRL) expression in the clinical specimens was evaluated by immunohistochemistry. Bone metastases were quantified by automated Bone Scan Index (aBSI). The study included 61 patients with a median follow-up of 19.0 months. Patients with lower baseline PRL levels (median) responded better to AA than those with higher baseline PRL levels as indicated by prostate-specific antigen (PSA) reduction (PSA90, 66.7% vs. 25.8%, p = 0.001), PFS (19.6vs. 7.9 months), and OS (52.8 vs. 19.2 months). Cox regression adjusted for clinical factors also confirmed that baseline PRL level was an independent predictive factor for PFS (hazard ratio = 1.096, p = 0.007). Prostatic PRL expression increased as the disease progressed. PRL expression was also detected in biopsy samples from bone metastasis but not in normal bone tissue, and the serum PRL levels were positively correlated with aBSIs (r = 0.28, p = 0.037). Serum PRL levels are predictive of response to AA in patients with mCRPC. Serum PRL levels are positively correlated with the volume of metastatic bone disease.

Prognostic Impact of Sarcopenia in Patients with Metastatic Hormone-Sensitive Prostate Cancer.

Simple SummaryAs sarcopenia is recognized as a poor prognostic factor in various type of cancers, we hypothesized that sarcopenia may also have adverse impact in patients with metastatic hormone-sensitive prostate cancer (mHSPC). In this study, we found that sarcopenia is an independent prognostic factor for poor failure-free survival and time to prostate-specific antigen progression in patients with mHSPC who receive early docetaxel or abiraterone acetate treatment. In addition, we performed RNA sequencing of primary tumors to further understand the biological perspective of the presence of sarcopenia in mHSPC. Transcriptomic differences were found between primary tumors with and without sarcopenia, which may have a potential to link between sarcopenia and poor clinical outcomes in these patients.The clinical value of sarcopenia has not been determined yet in metastatic hormone-sensitive prostate cancer (mHSPC). We retrospectively evaluated data of 70 consecutive patients with mHSPC receiving treatment with either early docetaxel (n = 42) or abiraterone acetate (n = 28) between July 2018 and April 2021. Skeletal muscle index was calculated from cross-sectional areas of skeletal muscle on baseline computed tomography (CT), defining sarcopenia as a skeletal muscle index of ≤52.4 cm2/m2. Failure-free survival (FFS), radiographic progression-free survival, and time to prostate-specific antigen (PSA) progression were estimated using the Kaplan–Meier method, and differences in survival probability were compared using the log-rank test. Cox proportional hazards regression analysis was conducted to identify the predictors of clinical outcomes. Patients with sarcopenia (n = 47) had shorter FFS than those without sarcopenia (n = 23) (median, 20.1 months vs. not reached; log-rank p < 0.001). Sarcopenia was independently associated with shorter FFS (hazard ratio (HR), 6.69; 95% confidence interval (CI), 1.57–28.49; p = 0.010) and time to PSA progression (HR, 12.91; 95% CI, 1.08–153.85; p = 0.043). In conclusion, sarcopenia is an independent prognostic factor for poor FFS and time to PSA progression in patients with mHSPC who receive early docetaxel or abiraterone acetate treatment.

Dose Finding and Food Effect Studies of a Novel Abiraterone Acetate Formulation for Oral Suspension in Comparison to a Reference Formulation in Healthy Male Subjects.

Currently approved formulations of the androgen synthesis inhibitor abiraterone acetate (AA) consist of multiple tablets administered daily in a fasted state. Removing the food effect and switching to a suspension formulation is expected to improve the pharmacokinetic profile and facilitate drug administration for patients with late-stage prostate cancer. Two four-sequence, four-period randomized crossover investigations were undertaken to establish the pharmacokinetic profiles of single doses of commercially available Zytiga®, as the reference AA (R-AA), and a novel tablet for oral suspension (TOS). Four single doses of TOS (from 62.5 to 250 mg) were compared in study C01, and two single doses each of TOS (250 mg) and R-AA (1000 mg) were compared under fasted and fed (modified fasted for R-AA) conditions in C02. Plasma concentrations of abiraterone over time were measured, and pharmacokinetic parameters were calculated. Each doubling of the dose of TOS was associated with a greater than 3-fold increase in exposure. A single dose of TOS (250 mg) exhibited similar exposure over 24 h, whether given fasted (625 ng × h/mL) or fed (485 ng × h/mL). A single dose of TOS (250 mg) was associated with higher (fasted, p = 0.028) or equivalent exposure (fed) compared to 1000 mg R-AA fasted (532 ng × h/mL). Substantially higher exposures were seen with 1000 mg R-AA under modified fasted conditions compared to TOS, irrespective of prandial status (p < 0.001). TOS was generally safe and well tolerated in the study. A 250 mg dose of a novel AA formulation for oral suspension demonstrated bioequivalence to 1000 mg R-AA under fasted conditions. This novel TOS formulation also addresses some of the limitations of current AA treatment, including low bioavailability, high variability in systemic exposure and a large food effect. It may offer an alternative for patients with dysphagia or discomfort with swallowing large pills.

RNA Biomarkers as a Response Measure for Survival in Patients with Metastatic Castration-Resistant Prostate Cancer.

Simple SummaryDespite the increasing number of treatments for advanced prostate cancer, the evaluation of the added value of each line of treatment on survival outcome is challenging. Therefore, biomarkers to discriminate short-term survivors from long-term survivors shortly after start of treatment are urgently needed. We demonstrate that in 93 patients with mCRPC treated with first-line abiraterone acetate or enzalutamide the addition of KLK3 and miR-375 (at baseline and 1 month) to standard clinical parameters resulted in the best prediction model for survival assessment.Treatment evaluation in metastatic castration-resistant prostate cancer is challenging. There is an urgent need for biomarkers to discriminate short-term survivors from long-term survivors, shortly after treatment initiation. Thereto, the added value of early RNA biomarkers on predicting progression-free survival (PFS) and overall survival (OS) were explored. The RNA biomarkers: KLK3 mRNA, miR-375, miR-3687, and NAALADL2-AS2 were measured in 93 patients with mCRPC, before and 1 month after start of first-line abiraterone acetate or enzalutamide treatment, in two prospective clinical trials. The added value of the biomarkers to standard clinical parameters in predicting PFS and OS was tested by Harell’s C-index. To test whether the biomarkers were independent markers of PFS and OS, multivariate Cox regression was used. The best prediction model for PFS and OS was formed by adding miR-375 and KLK3 (at baseline and 1 month) to standard clinical parameters. Baseline miR-375 and detectable KLK3 after 1 month of therapy were independently related to shorter PFS, which was not observed for OS. In conclusion, the addition of KLK3 and miR-375 (at baseline and 1 month) to standard clinical parameters resulted in the best prediction model for survival assessment.

Liquid biopsy reveals KLK3 mRNA as a prognostic marker for progression free survival in patients with metastatic castration-resistant prostate cancer undergoing first-line abiraterone acetate and prednisone treatment.

Circulating RNAs extracted from liquid biopsies represent a promising source of cancer‐ and therapy‐related biomarkers. We screened whole blood from patients with metastatic castration‐resistant prostate cancer (mCRPC) following their first‐line treatment with abiraterone acetate and prednisone (AA‐P) to identify circulating RNAs that may correlate with progression‐free survival (PFS). In a prospective multicenter observational study, 53 patients with mCRPC were included after they started first‐line AA‐P treatment. Blood was drawn at baseline, 1, 3, and 6 months after treatment initiation. The levels of predefined circulating RNAs earlier identified as being upregulated in patients with mCRPC (e.g., microRNAs, long noncoding RNAs, and mRNAs), were analyzed. Uni‐ and multivariable Cox regression and Kaplan–Meier analyses were used to analyze the prognostic value of the various circulating RNAs for PFS along treatment. Detectable levels of kallikrein‐related peptidase 3 (KLK3) mRNA at baseline were demonstrated to be an independent prognostic marker for PFS (201 vs 501 days, P = 0.00054). Three months after AA‐P treatment initiation, KLK3 could not be detected in the blood of responding patients, but was still detectable in 56% of the patients with early progression. Our study confirmed that KLK3 mRNA detection in whole blood is an independent prognostic marker in mCRPC patients receiving AA‐P treatment. Furthermore, the levels of circulating KLK3 mRNA in patients receiving AA‐P treatment might reflect treatment response or early signs of progression.

Abiraterone acetate in patients with metastatic castration-resistant prostate cancer, chemo-naive, who received a prior diethylstilbestrol therapy.

130 Background: The use of diethylstilbestrol (DES) for the treatment of metastatic castration resistant prostate cancer (mCRPC) is very common in developing countries. Retrospective data suggests that abiraterone acetate (AA) is active in patients that progressed to DES. This phase II study evaluated the efficacy and safety of abiraterone acetate in chemotherapy-naïve patients with metastatic CRPC who have progressed to DES. Methods: Patients with DES−refractory metastatic CRPC with ongoing ADT, serum testosterone level &lt; 50 ng/dL and ECOG of 0-2 were included. All patients received AA 1,000 mg with prednisone 5 mg once daily in a 28 days cycles. The primary endpoint was the time to PSA progression (PSAP) by PCWG2 and was previously reported. We present here secondary endpoints: overall survival, PSA response, maximum PSA change from baseline and safety. Results: A total of 46 patients were enrolled, median age was 69.8 years, 76% had gleason &gt; = 7 at diagnosis, median time from metastatic disease to DES discontinuation was 25.9 months, and a median duration of prior DES of 7.2 months. AA treatment resulted in median time to PSA progression of 7.3 months. PSA response rate (³ 50%) was 47.5% (95% CI: 36,1% to 68,5%) at 12 weeks and 57.5% (95% CI: 27.0% to 59.1%) at any time. 93.4% received chemotherapy after progression to AA. The median overall survival was 29.6 months. Substantial declines in serum androgens from baseline to week 12 occurred and in this group a higher proportion of PSA responses occurred. The incidence of adverse events (AEs) related to AA was 74% and prednisone 59%. Hypertension (21.7%), fatigue (19.6%) and oedema peripheral (13.0%) were the most frequent AA related AEs. The most frequent prednisone related AEs were hyperglycaemia (15.2%) hypertension (10.9%). Serious AEs occurred in 23.9% of subjects and 3 subjects (6.5%) died of AEs not related to study drugs. Conclusions: AA is well tolerated and demonstrated activity in mCRPC patients previously treated with DES, therefore it should be considered an option in chemo-naïve patients. Serum androgens levels tend to decrease with AA treatment and are associated with PSA responses. Clinical trial information: NCT02217566.

ARTO trial (NCT03449719), a randomized phase II trial enrolling oligometastatic castration-resistant prostate cancer patients treated with first-line abiraterone acetate with or without stereotactic body radiation therapy: Preliminary results comprehensive of biochemical outcomes and circulating tumor cells analysis.

118 Background: Androgen Receptor Targeted Agents (ARTA) represent one of the main treatment options for metastatic castrate resistant prostate cancer (mCRPC). Addition of stereotactic radiation therapy (SBRT) to ablate metastatic foci may improve clinical outcomes in oligometastatic setting. ARTO trial (NCT03449719) is a randomized phase II trial testing the benefit of upfront SBRT on all sites of metastatic disease in oligo-mCRPC patients undergoing I line therapy with Abiraterone Acetate (AA). In this preliminary analysis, we report results after 6 months of follow up, together with an exploratory analysis of androgen receptor splice variants (ARV7/ARFL) Prostate Specific Antigen (PSA) and Prostate Specific Membrane Antigen (PSMA) expression on Circulating Tumor Cells (CTCs) detected in this cohort of patients. Methods: 31 patients affected by oligo-mCRPC (defined as &lt; 3 non-visceral metastatic lesions) were randomized to receive I line AA therapy with or without SBRT on all metastatic sites. Baseline blood samples to detect CTCs and evaluate their ARV7, ARFL, PSA and PSMA expression were taken before AA treatment start. Assessments comprehensive of clinical examination and serum PSA were performed every three months. Toxicity was assessed by the Common Terminology Criteria for Adverse Events toxicity scale (CTCAE v.4.03). Results: Thirteen and 18 patients were enrolled in the treatment and control arm, respectively. Nineteen metastatic lesions were treated with SBRT in the treatment arm. At 6 months, complete response (defined as a serum PSA level &lt; 0.2 ng/dl) and biochemical response (defined as a PSA reduction &gt; 50% if compared to baseline) were achieved in 6 vs 4 and in 10 vs 8 patients in the treatment vs control arm, respectively. One patient in the treatment arm died for other causes, 1 biochemical progression occurred in the control arm. No adverse events occurred in both arms of treatment. CTCs analysis was available for 10 patients, out of whom 4 were found positive for CTCs (1 and 3 from the treatment and control arm, respectively). ARV7 and ARFL were expressed in 1 patient from the control arm, PSMA was expressed in all CTC positive patients, PSA was expressed in 2 patients from the control and one from the treatment arm. Conclusions: SBRT+AA in oligo-mCRPC patients was safe and yielded promising biochemical results. CTCs detection in this selected cohort of oligo-mCRPC was lower if compared to historical data of unselected mCRPC patients. Data about ARV7, ARFL, PSA and PSMA expression represent an interesting snapshot of biomarker arrangement in this setting. Clinical trial information: NCT03449719.

Abiraterone Acetate Induces CREB1 Phosphorylation and Enhances the Function of the CBP-p300 Complex, Leading to Resistance in Prostate Cancer Cells.

Abiraterone acetate (AA), an inhibitor of cytochrome P450 17alpha-hydroxylase/17, 20 lyase, is an FDA-approved drug for advanced prostate cancer. However, not all patients respond to AA, and AA resistance ultimately develops in patients who initially respond. We aimed to identify AA resistance mechanisms in prostate cancer cells. We established several AA-resistant cell lines and performed a comprehensive study on mechanisms involved in AA resistance development. RNA sequencing and phospho-kinase array screenings were performed to discover that the cAMP-response element CRE binding protein 1 (CREB1) was a critical molecule in AA resistance development. The drug-resistant cell lines are phenotypically stable without drug selection, and exhibit permanent global gene expression changes. The phosphorylated CREB1 (pCREB1) is increased in AA-resistant cell lines and is critical in controlling global gene expression. Upregulation of pCREB1 desensitized prostate cancer cells to AA, while blocking CREB1 phosphorylation resensitized AA-resistant cells to AA. AA treatment increases intracellular cyclic AMP (cAMP) levels, induces kinases activity, and leads to the phosphorylation of CREB1, which may subsequently augment the essential role of the CBP/p300 complex in AA-resistant cells because AA-resistant cells exhibit a relatively higher sensitivity to CBP/p300 inhibitors. Further pharmacokinetics studies demonstrated that AA significantly synergizes with CBP/p300 inhibitors in limiting the growth of prostate cancer cells. Our studies suggest that AA treatment upregulates pCREB1, which enhances CBP/p300 activity, leading to global gene expression alterations, subsequently resulting in drug resistance development. Combining AA with therapies targeting resistance mechanisms may provide a more effective treatment strategy.

Effects of abiraterone acetate plus prednisone on bone turnover markers in chemotherapy-naïve mCRPC patients after ADT failure: A prospective analysis of the italian real-world study ABITUDE

BackgroundBone remodeling is disrupted in metastatic disease, which affects > 70% of metastatic castration-resistant prostate cancer (mCRPC) patients. As a result, abnormal levels of specific bone turnover biomarkers (BTMs) are released. In this prospective ancillary analysis of the Italian real-world study ABITUDE, four markers were measured during abiraterone acetate plus prednisone (AAP) treatment in chemotherapy-naïve mCRPC men failing androgen-deprivation therapy. MethodsPatients were enrolled if a blood sample was obtained before the first administration of abiraterone (baseline); ad-hoc blood samples were withdrawn during routine tests after 3, 6, and 12 months. A centralized lab measured bone alkaline phosphatase (BALP, osteoblast activity marker), type-I collagen-C-telopeptide (CTX-1, bone resorption marker), parathyroid hormone (PTH) and vitamin D (vitD). At each time point, intra-patient variations vs baseline were compared by the signed-rank test (statistical significance: P-value < 0.05). ResultsOf 481 patients enrolled in ABITUDE, 186 (median age: 76 [range: 53–93] years) met the substudy criteria: 74.7% had bone metastases, 11.8% were on bone-targeted therapies (BTT) and 14.0% on vitD supplementation. BALP decreased significantly at month 6 (P = 0.0010) and 12 (P < 0.0001) and CTX-1 at month 6 (P = 0.0028); PTH increased at month 3 (P < 0.0001); no significant difference in vitD levels was observed. Similar findings were observed in BTT-untreated patients. The reduction in BALP and CTX-1 levels was more pronounced in patients with than without bone metastases; in the latter group, no significant variation in BALP and CTX-1 levels was observed. ConclusionsAAP seems to exert an effect on the microenvironment of metastatic but not of normal bone, which likely contributes to its antitumoral activity.

A high neutrophil-to-lymphocyte ratio is a poor prognostic factor for castration-resistant prostate cancer patients who undergo abiraterone acetate or enzalutamide treatment

BackgroundInflammatory cytokine markers, including the neutrophil-to-lymphocyte ratio (NLR), monocyte-lymphocyte ratio, and platelet-to-lymphocyte ratio, play important roles as prognostic markers in several solid malignancies, including prostate cancer. We previously reported the NLR as a poor prognostic marker in bladder cancer, upper-urothelial carcinoma, adrenocortical carcinoma, penile cancer, and prostate cancer. This study examined the importance of the NLR as a prognostic marker for castration-resistant prostate cancer (CRPC) patients who received abiraterone acetate or enzalutamide.MethodsA total of 805 prostate cancer patients developed in CRPC status were enrolled in this study. Of these patients, 449 received abiraterone acetate (ABI; 188 cases) or enzalutamide (ENZ; 261 cases) treatment, and the pre-treatment NLR values of these patients were obtained. We investigated the prognosis in those with higher and lower NLR values.ResultsThe median NLR was 2.90, and a receiver operating characteristics analysis suggested a candidate cut-off point of 3.02. The median overall survival (OS) was 17.3 months in the higher NLR group (≥3.02) and 27.3 months in the lower NLR group (< 3.02) (p < 0.0001). This trend was also observed in both the ABI and ENZ groups (ABI: 29.3 vs. 15.1 months; ENZ: NR vs. 19.5 months; p < 0.0001 and < 0.0001, respectively). A multivariate analysis revealed that a higher NLR was an independent risk factor. The NLR value was thus shown to be correlated with the prostate cancer progression.ConclusionsA higher NLR was associated with a poorer OS for CRPC patients who received ABI or ENZ. The NLR was positively correlated with prostate cancer progression.

Cost-Effectiveness Assessment of Monitoring Abiraterone Levels in Metastatic Castration-Resistant Prostate Cancer Patients

ObjectivesAbiraterone acetate is registered for the treatment of metastatic castration-sensitive and resistant prostate cancer (mCRPC). Treatment outcome is associated with plasma trough concentrations (Cmin) of abiraterone. Patients with a plasma Cmin below the target of 8.4 ng/mL may benefit from treatment optimization by dose increase or concomitant intake with food. This study aims to investigate the cost-effectiveness of monitoring abiraterone Cmin in patients with mCRPC. MethodsA Markov model was built with health states progression-free survival, progressed disease, and death. The benefits of monitoring abiraterone Cmin followed by a dose increase or food intervention were modeled via a difference in the percentage of patients achieving adequate Cmin taking a healthcare payer perspective. Deterministic and probabilistic sensitivity analyses were performed to assess uncertainties and their impac to the incremental cost-effectiveness ratio (ICER). ResultsMonitoring abiraterone followed by a dose increase resulted in 0.149 incremental quality-adjusted life-years (QALYs) with €22 145 incremental costs and an ICER of €177 821/QALY. The food intervention assumed equal effects and estimated incremental costs of €7599, resulting in an ICER of €61 019/QALY. The likelihoods of therapeutic drug monitoring (TDM) with a dose increase or food intervention being cost-effective were 8.04%and 81.9%, respectively. ConclusionsMonitoring abiraterone followed by a dose increase is not cost-effective in patients with mCRPC from a healthcare payer perspective. Monitoring in combination with a food intervention is likely to be cost-effective. This cost-effectiveness assessment may assist decision making in future integration of abiraterone TDM followed by a food intervention into standard abiraterone acetate treatment practices of mCRPC patients.