Abiraterone acetate in combination with androgen deprivation therapy compared to androgen deprivation therapy only for metastatic hormone-sensitive prostate cancer

BACKGROUND

Systemic androgen deprivation therapy (ADT), also referred to as hormone therapy,àhas long been the primary treatment for metastatic prostate cancer. Additional agents have been reserved for the castrate-resistant disease stage when ADT start becoming less effective. Abiraterone is an agent with an established role in that disease stage, which has only recently been evaluated in the hormone-sensitive setting.

OBJECTIVES

To assess the effects of early abiraterone acetate, in combination with systemic ADT, for newly diagnosed metastatic hormone-sensitive prostate cancer.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, six other databases, two trials registries, grey literature, and conference proceedings, up to 15 May 2020. We applied no restrictions on publication language or status.

SELECTION CRITERIA

We included randomized trials, in which men diagnosed with hormone-sensitive prostate cancer were administered abiraterone acetate and prednisolone with ADT or ADTàalone.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified studies and abstracted data from the included studies. We performed statistical analyses using a random-effects model. We rated the quality of evidence according to the GRADE approach.

MAIN RESULTS

The search identified two randomized controlled trials (RCT), with 2201 men, who were assigned to receive either abiraterone acetate 1000 mg once daily and low dose prednisone (5mg) in addition to ADT, or ADT alone. In the LATITUDE trial, the median age and range of men in the intervention group was 68 (38 to 89) years, and 67 (33 to 92) years in the control group. Nearly all of the men in thisàstudy (97.6%) had prostate cancer with a Gleason score of at least 8 (ISUP grade group 4). Primary outcomes The addition of abiraterone acetate to ADT reduces the probability of death from any cause compared to ADT alone (hazard ratio [HR] 0.64, 95% confidence interval [CI] 0.56 to 0.73; 2 RCTs, 2201 men; high certainty of evidence); this corresponds to 163 fewer deaths per 1000 men with hormone-sensitive metastaticàprostate cancerà(210 fewer to 115 fewer) at five years. Abiraterone acetate in addition to ADT probably results in little to no differenceàin quality of life compared to ADT alone, measured with the Functional Assessment of Cancer Therapy-prostate total score (FACT-P; range 0 to 156; higher values indicates better quality of life),àat 12 months (mean difference [MD] 2.90 points, 95% CI 0.11 to 5.60; 1 RCT, 838 men; moderate certainty of evidence). Secondary outcomes Abiraterone plus ADT increases the risk of grades III to V adverse events compared to ADT alone (risk ratio [RR] 1.34, 95% CI 1.22 to 1.47; 1 RCT, 1199 men; high certainty of evidence); this corresponds to 162 more grade III to Vàevents per 1000 men with hormone-sensitive metastaticàprostate cancerà(105 more to 224 more) at a median follow-up of 30àmonths. Abiraterone acetate in addition to ADT probably reduces the probability of death due to prostate cancer compared to ADT alone (HR 0.58, 95% CI 0.50 to 0.68; 2 RCTs, 2201 men; moderate certainty of evidence). This corresponds to 120 fewer death from prostate cancer per 1000 men with hormone-sensitive metastaticàprostate cancerà(95% CI 145 fewer to 90 fewer) afteràa median follow-up of 30 months. The addition of abiraterone acetate to ADT probably decreases the probability of disease progression compared to ADT alone (HR 0.35, 95%CI 0.26 to 0.49; 2 RCTs, 2097 men; moderate certainty of evidence). This corresponds to 369 fewer incidences of disease progression per 1000 men with hormone-sensitive metastaticàprostate cancerà(456 fewer to 256 fewer)àafter a median follow-up of 30 months. The addition of abiraterone acetate to ADT probably increases the risk of discontinuing treatment due to adverse events compared to ADT alone (RR 1.50, 95% CI 1.17 to 1.92; 1 RCT, 1199 men; moderate certainty of evidence). This corresponds to 51 more men (95% CI 17 more to 93 more) discontinuing treatment because of adverse events per 1000 men treated with abiraterone acetate and ADT compared to ADT alone afteràa median follow-up of 30 months.

AUTHORS' CONCLUSIONS

The addition of abiraterone acetate to androgen deprivation therapy improves overall survival but probably not quality of life. Itàprobably also extends disease-specific survival, and delays disease progression compared to androgen deprivation therapy alone. However, the risk of grades III to V adverse events is increased, and probably, so is the risk of discontinuing treatment due to adverse events.

A Retrospective Observational Analysis of Overall Survival with Sipuleucel-T in Medicare Beneficiaries Treated for Advanced Prostate Cancer

Introduction

Since sipuleucel-T approval in 2010, the treatment landscape for metastatic castration-resistant prostate cancer (mCRPC) now includes the androgen-receptor signaling pathway inhibitors (ASPIs) abiraterone acetate or enzalutamide. In 2013 and 2014, these oral agents were approved for use in men with metastatic prostate cancer who had minimal to no symptoms. We compared overall survival (OS) in men who received their first mCRPC treatment using the Medicare Fee-for-Service 100% administrative claims research dataset with patient-level linkage to the National Death Index.

Methods

This retrospective cohort analysis (January 2013 to December 2017) included men who were chemo-naïve at treatment start in 2014 and who had continuous Medicare Parts A, B, and D eligibility during the 3-year observation period. We compared: first-line sipuleucel-T vs. first-line ASPIs and any-line sipuleucel-T vs. any-line ASPIs (without sipuleucel-T). We used a multivariable regression model to help control for potentially confounding factors while assessing survival outcomes.

Results

The model included 6044 eligible men (average age 75–78 years) with similar disease severity; > 80% were white. Median OS, presented as sipuleucel-T vs. ASPI, was 35.2 vs. 20.7 months (n, 906 vs. 5092; any-line cohort) and 34.9 vs. 21.0 months (n, 647 vs. 4810; first-line cohort). Model outcomes indicated sipuleucel-T was associated with significantly prolonged OS compared with ASPIs: adjusted hazard ratio, 0.59 (95% CI 0.527–0.651) and 0.56 (0.494–0.627) for the any-line and first-line cohorts, respectively.

Conclusion

This analysis suggests use of sipuleucel-T at any time was associated with improved OS compared with ASPI use alone. Of note, these analyses are intended as descriptive rather than definitive as this dataset contains limited data on key clinical factors. While selection bias is a risk in secondary claims data, this research provides important insight into real-world treatment outcomes.

Electronic Supplementary Material

The online version of this article (10.1007/s12325-020-01509-5) contains supplementary material, which is available to authorized users.

Evaluation of Fall and Fracture Risk Among Men With Prostate Cancer Treated With Androgen Receptor Inhibitors: A Systematic Review and Meta-analysis

Importance

A high incidence of fall and fracture in a subset of patients treated with androgen receptor inhibitors (ARIs) has been reported, although the relative risk (RR) of fall and fracture for patients who receive ARI treatment is unknown.

Objective

To evaluate whether treatment with ARIs is associated with an elevated relative risk for fall and fracture in patients with prostate cancer.

Data Sources

Cochrane, Scopus, and MedlinePlus databases were searched from inception through August 2019.

Study Selection

Randomized clinical trials comparing patients with prostate cancer treated with any ARI or placebo were included.

Data Extraction and Synthesis

Two independent reviewers used a standardized data extraction and quality assessment form. A mixed effects model was used to estimate the effects of ARI on relative risk, with included studies treated as random effects and study groups treated as fixed effects in the pooled analysis. Sample size for each study was used to weight the mixed model. Statistical analysis was performed from August to October 2019.

Main Outcomes and Measures

The primary outcome was RR of fall and fractures for patients receiving ARI treatment.

Results

Eleven studies met this study's inclusion criteria. The total population was 11 382 men (median [range] age: 72 [43-97] years), with 6536 in the ARI group and 4846 in the control group. Participants in the ARI group could have received enzalutamide, apalutamide, or darolutamide in combination with androgen deprivation therapy or other enzalutamide combinations; patients in the control group could have received placebo, bicalutamide, or abiraterone. The reported incidence of fall was 525 falls (8%) in the ARI group and 221 falls (5%) in the control group. The incidence of fracture was 242 fractures (4%) in the ARI group and 107 fractures (2%) in the control group. Use of an ARI was associated with an increased risk of falls and fractures: all-grade falls (RR, 1.8; 95% CI, 1.42-2.24; P < .001); grade 3 or greater fall (RR, 1.6; 95% CI, 1.27-2.08; P < .001); all-grade fracture (RR, 1.59; 95% CI, 1.35-1.89; P < .001), and likely grade 3 or greater fracture (RR, 1.71; 95% CI, 1.12-2.63; P = .01).

Conclusions and Relevance

Use of ARI was associated with an increase in falls and fractures in patients with prostate cancer as assessed by a retrospective systematic review and meta-analysis. Further studies are warranted to identify and understand potential mechanisms and develop strategies to decrease falls and fractures associated with ARI use.

Impact of clinical versus radiographic progression on clinical outcomes in metastatic castration-resistant prostate cancer

OBJECTIVES

Unequivocal clinical progression (UCP)-a worsening of clinical status with or without radiographic progression (RAD)-represents a distinct mode of disease progression in metastatic prostate cancer. We evaluated the prevalence, risk factors and the impact of UCP on survival outcomes.

METHODS

A post-hoc analysis of the COU-AA-302, a randomised phase 3 study of abiraterone plus prednisone (AAP) versus prednisone was performed. Baseline characteristics were summarised. Cox proportional-hazards model and Kaplan-Meier method were used for survival and time to event analyses, respectively. Iterative multiple imputation method was used for correlation between clinicoradiographic progression-free survival (crPFS) and overall survival (OS).

RESULTS

Of 736 patients with disease progression, 280 (38%) had UCP-only and 124 (17%) had UCP plus RAD. Prognostic index model high-risk group was associated with increased likelihood of UCP (p<0.0001). Median OS was 25.7 months in UCP-only and 33.0 months for RAD-only (HR 1.39; 95% CI 1.16 to 1.66; p=0.0003). UCP adversely impacted OS in both treatment groups. Lowest OS was seen in patients with prostate specific antigen (PSA)-non-response plus UCP-only progression (median OS 22.6 months (95% CI 20.7 to 24.4)). Including UCP events lowered estimates of treatment benefit-median crPFS was 13.3 months (95% CI 11.1 to 13.8) versus median rPFS of 16.5 months (95% CI 13.8 to 16.8) in AAP group. Finally, crPFS showed high correlation with OS (r=0.67; 95% CI 0.63 to 0.71).

CONCLUSIONS

UCP is a common and clinically relevant phenomenon in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with AAP or prednisone. UCP is prognostic and associated with inferior OS and post-progression survival. A combination of PSA-non-response and UCP identifies patients with poorest survival. When included in PFS analysis, UCP diminishes estimates of treatment benefit. Continued study of UCP in mCRPC is warranted.

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

BACKGROUND

Inflammatory 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.

METHODS

A 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.

RESULTS

The 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.

CONCLUSIONS

A 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.

Clinical outcomes of abiraterone acetate and predictors of its treatment duration in metastatic castration-resistant prostate cancer: Real-world experience in the Southeast Asian cohort

It is of much interest to understand the efficacy of abiraterone acetate (AA) in routine clinical practice. We assessed the clinical outcome of AA in patients with metastatic castration-resistant prostate cancer (mCRPC) and determined clinical factors associated with AA treatment duration in real-world setting. This real-world cohort consisted of 93 patients with mCRPC treated with AA in Thailand (58.1%) and Malaysia (41.9%). Primary endpoints were overall survival (OS) and biochemical progression-free survival (bPFS). Secondary endpoints were predictors associated with AA treatment duration evaluated with Cox proportional hazards regression. Around 74% were chemotherapy-naïve. The median AA treatment duration was 10 months (IQR 5.6-17.1). Malaysians had a relatively lower median OS and bPFS (OS 17.8 months; 95% CI 6.4-29.1, bPFS 10.4 months; 95% CI 8.8-12.0) compared to Thais (OS 27.0 months; 95% CI 11.3-42.7, bPFS 14.0 months; 95% CI 5.8-22.2), although it did not achieve statistical significance (P > .05). Patients with longer AA treatment duration (>10 months) had lower risk of death and longer bPFS, compared to those with shorter AA treatment duration (≤10 months) (hazard ratio [HR] 0.10, 95% CI 0.05-0.22 and HR 0.13, 95% CI 0.06-0.25, respectively). Multivariable analysis showed that PSA at AA initiation, presence of PSA response and chemotherapy-naive were independently associated with AA duration (P < .05). Abiraterone acetate is well-tolerated in the Southeast Asian cohort with comparable survival benefits to other Asian populations in real-world setting. Lower PSA levels at AA initiation, presence of PSA response, and chemotherapy-naive were significant in determining AA treatment duration.

Early PSA response to antiandrogen therapy in metastatic castration-resistant prostate carcinoma patients: A predictive marker for progression-free survival?

PURPOSE

Enzalutamide and abiraterone acetate (AA) are the main therapeutic approaches for the treatment of metastatic castration-resistant prostate cancer (mCRPC) after the failure of androgen deprivation therapy during or following docetaxel-based chemotherapy. The aim of the present study was to investigate the role of early prostate-specific antigen (PSA) decline (four weeks after anti-androgen therapy) in predicting long-term progression-free survival (PFS).

METHODS

In this retrospective study, we evaluated 65 patients who had histologically confirmed metastatic prostate cancer and were treated with AA or enzalutamide in the post-docetaxel period. Serum PSA levels were evaluated at 4th and then 12th week. The main goal of this study was to demonstrate that an early PSA decline predicts PFS.

RESULTS

Between May 2015 and June 2019, the medical records of 65 patients were collected. Of these patients, 38 (58.5%) received AA and 27 (41.5%) enzalutamide. Early PSA response rate (RR; ≥ 30% and ≥ 50% from baseline at the 4th week) was identified in 38.5% (n=25) and 15.3% (n=10) of the patients, respectively. In multivariate analysis, we found that PSA RR≥ 30% in patients had a statistically significant advantage in terms of PFS ( HR: 0.38, 95% CI (0.13-0.71;p=0.03).

CONCLUSION

In conclusion, 30% PSA RR was significantly associated with a better PFS.

Adrenocortical Carcinoma Xenograft in Zebrafish Embryos as a Model To Study the In Vivo Cytotoxicity of Abiraterone Acetate

Abiraterone acetate (AbiAc) inhibits tumor growth when administered to immunodeficient mice engrafted with the in vitro cell model of human adrenocortical carcinoma (ACC). Here, we developed and validated a zebrafish model engrafted with cortisol-secreting ACC cells to study the effects of AbiAc on tumor growth. The experimental conditions for AbiAc absorption in AB zebrafish embryos including embryo number, AbiAc concentration, and absorption time curve by liquid chromatography-tandem mass spectrometry were set up. The AbiAc effect on steroid production in AB zebrafish embryos was measured as well. ACC cells (the NCI-H295R cell line, the primary cell ACC29, and the negative control cell SW13) were treated with drug-induced liver injury fluorescent dye, and ∼240 cells per 4 nL was injected in the subperidermal space of the yolk sac of AB zebrafish embryos (n = 80 ± 10). The cell area was measured with Noldus DanioScopeTM software. AbiAc absorption in AB zebrafish embryos was stage dependent. Abiraterone (Abi) concentration decreased, whereas its main metabolite, Δ4A, increased. Accordingly, we demonstrated that zebrafish expressed mRNA encoding the enzyme 3β-hydroxysteroid dehydrogenase, which converts Abi in Δ4A. Furthermore, ABiAc reduced cortisol production and increased progesterone in zebrafish embryos. Three days after cell injection, the cortisol-secreting ACC cell area in solvent-treated embryos was significantly higher than that in 1 µM AbiAC‒treated embryos, whereas no AbiAc effect was observed in SW13 cells, which lack the Abi target enzyme CYP17A1.Zebrafish embryos xenografted with ACC tumor cells could be a useful, fast, and reproducible experimental model to preclinically test the activity of new drugs in human ACC.

Combining prostate cancer radiotherapy with therapies targeting the androgen receptor axis

Background

Prostate cancer (pca) is the most common non-dermatologic cancer and the 3rd leading cause of male cancer mortality in Canada. In patients with high-risk localized or recurrent pca, management typically includes the combination of long-term androgen deprivation therapy (adt) and radiotherapy (rt). New androgen-receptor-axis targeted therapies (arats), which await validation, offer an option to intensify therapy.

Methods

In this narrative review, we report the relevant history that has supported combining adt with rt. The literature in PubMed was searched for studies involving pca and novel arats (abiraterone acetate, enzalutamide, apalutamide, darolutamide) published between 1995 and 2019. Literature discussing clinical trials in which those modalities were combined was extracted and synthesized into a combined molecular and clinical discussion. Potential treatment intensification mechanisms and rationales are explored.

Results

Early results from three phase i/ii trials demonstrated that concurrent abiraterone acetate, adt, and rt is safe, improves the extent of chemical castration, and is associated with limited treatment failures. A single in vitro study implies synergy for radiosensitization beyond that facilitated by conventional adt. Studies investigating the combination of other arats with rt are under way, including multiple phase iii trials, but short-term results are not yet available.

The LACOG-0415 phase II trial: abiraterone acetate and ADT versus apalutamide versus abiraterone acetate and apalutamide in patients with advanced prostate cancer with non-castration testosterone levels

BACKGROUND

Testosterone suppression is the standard treatment for advanced prostate cancer, and it is associated with side-effects that impair patients' quality of life, like sexual dysfunction, osteoporosis, weight gain, and increased cardiovascular risk. We hypothesized that abiraterone acetate with prednisone (AAP) and apalutamide, alone or in combination, can be an effective hormonal therapy also possibly decreasing castration-associated side effects.

METHODS

Phase II, open-label, randomized, efficacy trial of abiraterone acetate plus prednisone (AAP) and Androgen Deprivation Therapy (ADT) versus apalutamide versus the combination of AAP (without ADT) and apalutamide. Key eligibility criteria are confirmed prostate adenocarcinoma; biochemical relapse after definitive treatment (PSA ≥ 4 ng/ml and doubling time less than 10 months, or PSA ≥ 20 ng/ml); newly diagnosed locally advanced or metastatic prostate cancer; asymptomatic to moderately symptomatic regarding bone symptoms. Patients with other histology besides adenocarcinoma or previous use of hormonal therapy or chemotherapy were excluded.

DISCUSSION

There is an urgent need to study and validate regimens such as new hormonal agents that may add benefit to castration with an acceptable safety profile. We aim to evaluate if apalutamide in monotherapy or in combination with AAP is an effective and safety hormonal treatment that can spare patients of androgen deprivation therapy.

TRIAL REGISTRATION

This trial was registered in ClinicalTrials.gov on October 16, 2017, under Identifier: NCT02867020.

Abiraterone Acetate: A Review in Metastatic Castration-Resistant Prostrate Cancer

Oral abiraterone acetate (Zytiga^®) is a selective inhibitor of CYP17 and thereby inhibits androgen biosynthesis, with androgen signalling crucial in the progression from primary to metastatic prostate cancer (PC) and subsequently, in the development of metastatic castration-resistant PC (mCRPC). In large phase 3 trials and in the clinical practice setting, oral abiraterone acetate in combination with prednisone was an effective treatment and had an acceptable, manageable tolerability and safety profile in chemotherapy-naive and docetaxel-experienced men with mCRPC. In the pivotal global phase 3 trials, relative to placebo (+prednisone), abiraterone acetate (+prednisone) prolonged overall survival (OS) at data maturity (final analysis) and radiographic progression-free survival (rPFS) at all assessed timepoints. Given its efficacy in prolonging OS and its convenient once-daily oral regimen, in combination with prednisone, abiraterone acetate is an important first-line option for the treatment of mCRPC.

Systemic and tumor-directed therapy for oligometastatic prostate cancer: study protocol for a phase II trial for veterans with de novo oligometastatic disease

BACKGROUND

The treatment paradigm for metastatic hormone-sensitive prostate cancer (mHSPC) patients is evolving. PET/CT now offers improved sensitivity and accuracy in staging. Recent randomized trial data supports escalated hormone therapy, local primary tumor therapy, and metastasis-directed therapy. The impact of combining such therapies into a multimodal approach is unknown. This Phase II single-arm clinical trial sponsored and funded by Veterans Affairs combines local, metastasis-directed, and systemic therapies to durably render patients free of detectable disease off active therapy.

METHODS

Patients with newly-diagnosed M1a/b prostate cancer (PSMA PET/CT staging is permitted) and 1-5 radiographically visible metastases (excluding pelvic lymph nodes) are undergoing local treatment with radical prostatectomy, limited duration systemic therapy for a total of six months (leuprolide, abiraterone acetate with prednisone, and apalutamide), metastasis-directed stereotactic body radiotherapy (SBRT), and post-operative fractionated radiotherapy if pT ≥ 3a, N1, or positive margins are present. The primary endpoint is the percent of patients achieving a serum PSA of < 0.05 ng/mL six months after recovery of serum testosterone ≥150 ng/dL. Secondary endpoints include time to biochemical progression, time to radiographic progression, time to initiation of alternative antineoplastic therapy, prostate cancer specific survival, health related quality-of-life, safety and tolerability.

DISCUSSION

To our knowledge, this is the first trial that tests a comprehensive systemic and tumor directed therapeutic strategy for patients with newly diagnosed oligometastatic prostate cancer. This trial, and others like it, represent the critical first step towards curative intent therapy for a patient population where palliation has been the norm.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT03298087 (registration date: September 29, 2017).

Hormone naïve metastatic prostate cancer: How to treat it?

OBJECTIVES

Recent landmark studies (GETUG-AFU 15, CHAARTED, STAMPEDE (docetaxel), LATITUDE and STAMPEDE (abiraterone)) have changed the treatment of hormone sensitive metastatic prostate cancer (mHSPC) from androgen deprivation therapy (ADT) only to combined therapy with either docetaxelor abiraterone acetate plus prednisone (AAP) together with ADT. In this Review we highlight current evidence and recommendations on how to treat men with newly diagnosed mHSPC beyond ADT. METHODS: Narrative overview of available evidence retrieved from pubmed searches, hand searches and authoritative texts.

RESULTS

Docetaxel or AAP in combination with ADT improves overall survival (OS) in men fit for combined treatment presenting with newly diagnosed mHSPC. The strongest evidence is for men with high volume mHSPC (four or more bone metastases with at least one outside the axial skeleton and/or visceral metastases) or mHSPC with high risk features (A minimum of two out of three following high-risk features: Gleason score ≥ 8, ≥ 3 bone lesions or visceral metastasis) as per CHAARTED and LATITUDE criteria, respectively. While upfront docetaxel and AAP yield comparable OS improvement, docetaxel has not been shown to increase OS specifically for men with low volume/low risk mHSPC, whereas, a recent post-hoc analysis from the STAMPEDE (abiraterone) trial showed consistent overall survival benefit of AAP plus ADT independent of risk stratification. While these data are limited by their retrospective nature, they do suggest that patients with low-risk mHSPC should be offered AAP. In men with high volume/high risk mHSPC, choosing between six-cycles of docetaxel or AAP until disease progression relies on patient preference, cost and individual assessment of which drug side-effect profile is most suitable.

CONCLUSION

Offer men presenting with newly diagnosed mHSPC fit enough for combined therapy either ADT plus docetaxel or AAP.

Abiraterone in metastatic castration-resistant prostate cancer: Efficacy and safety in unselected patients

BACKGROUND

Abiraterone acetate (AA), an androgen biosynthesis inhibitor, is now a standard of care for men with metastatic, castration-sensitive and castration-resistant prostate cancer (mCRPC). Data exploring real-world toxicity and outcomes are scarce.

METHODS

Retrospective study on unselected patients with mCRPC on AA plus steroids.

RESULTS

93 patients were included in the study. Median duration of treatment by AA was 7.5 months (95% CI 5.7-12) among the 58 patients pretreated with chemotherapy, versus 12.7 months ( 95% CI 8.2-35.9) among the 33 chemo-naive patients. Median survivals would reach 13.4 months (95% CI 10.2-19.1) and 36.4 months (95% CI 24.7-41.5) respectively. Rates of hypokalemia, peripheral edema, hypertension, cardiac failure, and overall survival assessments in patients with and without prior chemotherapy were similar to that previously reported in phase 3 randomized trials. The median survival time without adverse event of special interest was 7.5 months for hypokalemia and hypertension, and 5.3 months for liver-function test abnormalities (it was not reached for cardiac disorders).

CONCLUSION

Our findings provide further evidence for the survival benefits of AA with a low frequency of additional adverse events among unselected patients. In patients who have not developed hypokalemia or a transaminase increase within 7.5 and 5.3 months respectively, a lighter systematic monitoring may be considered.

AR-V7 in circulating tumor cells cluster as a predictive biomarker of abiraterone acetate and enzalutamide treatment in castration-resistant prostate cancer patients

OBJECTIVE

We examined whether androgen receptor splice variant 7 (AR-V7) in circulating tumor cell(CTC)clusters can be used to predict survival in patients with bone metastatic castration resistant-prostate cancer (mCRPC) treated with abiraterone or enzalutamide.

METHODS

We retrospectively enrolled 98 patients with CRPC on abiraterone or enzalutamide, and investigated the prognostic value of CTC cluster detection (+ v -) and AR-V7 detection (+ v -) using a CTC cluster detection - based AR-V7 mRNA assay. We examined ≤50% prostate-specific antigen (PSA) responses, PSA progression-free survival (PSA-PFS), clinical and radiological progression-free survival (radiologic PSF), and overall survival (OS). We then assessed whether AR-V7 expression in CTC clusters identified after On-chip multi-imaging flow cytometry was related to disease progression and survival after first-line systemic therapy.

RESULTS

All abiraterone-treated or enzalutamide-treated patients received prior docetaxel. The median follow-up was 20.7 (range: 3.0-37.0) months in the abiraterone and enzalutamide cohorts, respectively. Forty-nine of the 98 men (50.0%) were CTC cluster (-), 23 of the 98 men (23.5%) were CTC cluster(+)/AR-V7(-), and 26 of the 98 men (26.5%) were CTC cluster(+)/AR-V7(+). CTC cluster(+)/AR-V7(+) patients were more likely to have EOD ≥3 at diagnosis (P = 0.003), pain (P = 0.023), higher alkaline phosphatase levels (P < 0.001), and visceral metastases (P < 0.001). On multivariable analysis, pretherapy CTC cluster(+), CTC cluster(+)/AR-V7(-), and ALP >UNL were independently associated with a poor PSA-PFS, radiographic PFS, and OS in abiraterone-treated patients and enzalutamide-treated patients.

CONCLUSION

The CTC clusters and AR-V7-positive CTC clusters detected were important for assessing the response to abiraterone or enzalutamide therapy and for predicting disease outcome.

Recent Advances in Prostate Cancer Treatment and Drug Discovery

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.

What is the optimal systemic treatment of men with metastatic, hormone-naive prostate cancer? A STOPCAP systematic review and network meta-analysis

Background

Our prior Systemic Treatment Options for Cancer of the Prostate systematic reviews showed improved survival for men with metastatic hormone-naive prostate cancer when abiraterone acetate plus prednisolone/prednisone (AAP) or docetaxel (Doc), but not zoledronic acid (ZA), were added to androgen-deprivation therapy (ADT). Trial evidence also suggests a benefit of combining celecoxib (Cel) with ZA and ADT. To establish the optimal treatments, a network meta-analysis (NMA) was carried out based on aggregate data (AD) from all available studies.

Methods

Overall survival (OS) and failure-free survival data from completed Systemic Treatment Options for Cancer of the Prostate reviews of Doc, ZA and AAP and from recent trials of ZA and Cel contributed to this comprehensive AD-NMA. The primary outcome was OS. Correlations between treatment comparisons within one multi-arm, multi-stage trial were estimated from control-arm event counts. Network consistency and a common heterogeneity variance were assumed.

Results

We identified 10 completed trials which had closed to recruitment, and one trial in which recruitment was ongoing, as eligible for inclusion. Results are based on six trials including 6204 men (97% of men randomised in all completed trials). Network estimates of effects on OS were consistent with reported comparisons with ADT alone for AAP [hazard ration (HR) = 0.61, 95% confidence interval (CI) 0.53-0.71], Doc (HR = 0.77, 95% CI 0.68-0.87), ZA + Cel (HR = 0.78, 95% CI 0.62-0.97), ZA + Doc (HR = 0.79, 95% CI 0.66-0.94), Cel (HR = 0.94 95% CI 0.75-1.17) and ZA (HR = 0.90 95% CI 0.79-1.03). The effect of ZA + Cel is consistent with the additive effects of the individual treatments. Results suggest that AAP has the highest probability of being the most effective treatment both for OS (94% probability) and failure-free survival (100% probability). Doc was the second-best treatment of OS (35% probability).

Conclusions

Uniquely, we have included all available results and appropriately accounted for inclusion of multi-arm, multi-stage trials in this AD-NMA. Our results support the use of AAP or Doc with ADT in men with metastatic hormone-naive prostate cancer. AAP appears to be the most effective treatment, but it is not clear to what extent and whether this is due to a true increased benefit with AAP or the variable features of the individual trials. To fully account for patient variability across trials, changes in prognosis or treatment effects over time and the potential impact of treatment on progression, a network meta-analysis based on individual participant data is in development.

Modeling Clinical Outcomes in Prostate Cancer: Application and Validation of the Discrete Event Simulation Approach

OBJECTIVES

Treatment landscape in prostate cancer has changed dramatically with the emergence of new medicines in the past few years. The traditional survival partition model (SPM) cannot accurately predict long-term clinical outcomes because it is limited by its ability to capture the key consequences associated with this changing treatment paradigm. The objective of this study was to introduce and validate a discrete-event simulation (DES) model for prostate cancer.

METHODS

A DES model was developed to simulate overall survival (OS) and other clinical outcomes based on patient characteristics, treatment received, and disease progression history. We tested and validated this model with clinical trial data from the abiraterone acetate phase III trial (COU-AA-302). The model was constructed with interim data (55% death) and validated with the final data (96% death). Predicted OS values were also compared with those from the SPM.

RESULTS

The DES model's predicted time to chemotherapy and OS are highly consistent with the final observed data. The model accurately predicts the OS hazard ratio from the final data cut (predicted: 0.74; 95% confidence interval [CI] 0.64-0.85 and final actual: 0.74; 95% CI 0.6-0.88). The log-rank test to compare the observed and predicted OS curves indicated no statistically significant difference between observed and predicted curves. However, the predictions from the SPM based on interim data deviated significantly from the final data.

CONCLUSIONS

Our study showed that a DES model with properly developed risk equations presents considerable improvements to the more traditional SPM in flexibility and predictive accuracy of long-term outcomes.

Clinical Outcomes of First-line Abiraterone Acetate or Enzalutamide for Metastatic Castration-resistant Prostate Cancer After Androgen Deprivation Therapy + Docetaxel or ADT Alone for Metastatic Hormone-sensitive Prostate Cancer

BACKGROUND

The CHAARTED (ChemoHormonal Therapy Versus Androgen Ablation Randomized Trial for Extensive Disease in Prostate Cancer) and STAMPEDE (Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy) trials showed that the addition of docetaxel (D) to androgen deprivation therapy (ADT) prolonged longevity of men with metastatic hormone-sensitive prostate cancer (mHSPC). However, the impact of upfront D on subsequent therapies is still unexplored. As abiraterone acetate (AA) and enzalutamide (E) are the most commonly used first-line treatment for metastatic castration-resistant prostate cancer (mCRPC), we aimed to assess whether they maintained their efficacy after ADT+D versus ADT alone.

PATIENTS AND METHODS

A cohort of patients with mCRPC treated between 2014 and 2017 with first-line AA or E for mCRPC was identified from 3 hospitals' institutional review board-approved databases. Patients were classified by use of D for mHSPC. This time frame was chosen as ADT+D became a valid therapeutic option for mHSPC in 2014, and it inherently entailed a short follow-up time on AA/E. The endpoints included overall survival from ADT start, overall survival from AA/E start, and time to AA/E start from ADT start. Differences between groups were assessed using the log-rank test.

RESULTS

Of the 102 patients with mCRPC identified, 50 (49%) had previously received ADT alone, while 52 (51%) had ADT+D. No statistically significant difference in any of the evaluated outcomes was observed between the 2 cohorts. Yet, deaths in the ADT+D group were 12 versus 21 in the ADT alone, after a median follow-up of 24.4 and 29.8 months, respectively.

CONCLUSION

In a cohort of ADT/ADT+D-treated patients with mCRPC with short times to first-line AA/E and follow-up, the efficacy of AA/E is similar regardless of previous use of D.

[Maximal androgen deprivation with abiraterone acetate in hormone sensitive prostate cancer.]

OBJECTIVES

The treatment of metastatic prostate cancer has remained unchanged for more than 70 years, based on androgen deprivation therapy (ADT). In 2015, following the CHAARTED and STAMPEDE trials, it was established that the addition of 6 cycles of docetaxel to ADT was associated with significantly increased survival. In June 2017, the LATITUDE trial and the G arm of the STAMPEDE trial showed that the addition of Abiraterone with Prednisone (5 mg/day) to ADT was also associated with a significant increase in survival in metastatic patients. The present study analyzes these two trials.

RESULTS

LATITUDE demonstrated a 38% reduction in the risk of death (HR=0.62, 95% CI, 0.61-0.76) in almost all sub-groups. Risk reduction for radiological progression was 53% (HR=0.47, 95% CI 0.39-0.55). Secondary objectives such as prostate specific antigen progression, time to chemotherapy or a new skeletal event are also significantly delayed. STAMPEDE also showed that the combination of Abiraterone and Prednisone is associated with a 37% increase in survival (HR=0.63, 95% CI, 0.52- 0.76, p<0.001) in metastatic patients, but not in nonmetastatic patients. Progression-free survival was greatly improved in this arm (HR=0.29, 95% CI 0.25-0.34, p<0.001). The side effects reported show the known pattern of mineral corticosteroid excess with increased blood pressure, hypokalemia, and of liver enzymes elevation.

CONCLUSIONS

The indirect comparison of docetaxel and abiraterone studies confirms that both populations and results are comparable. Two comparative indirect metanalysis (>6000 patients) gave marginal superiority to abiraterone. In favor of abiraterone we have that it is an oral, comfortable medication with a good tolerance profile and side effects that are easy to manage, useful in patients who are old and fragile, in whom chemotherapy may not be indicated; the downsides are prolonged exposure to the drug and its current price. Future trials, currently in progress, will determine the ideal patient profile, or a potential association of both therapies.

Treatment of Metastatic, Castration-resistant, Docetaxel-resistant Prostate Cancer: A Systematic Review of Literature With a Network Meta-analysis of Randomized Clinical Trials

INTRODUCTION

To compare the efficacy of abiraterone acetate, enzalutamide, cabazitaxel and Radium-223 in the treatment of castration-resistant, docetaxel-resistant metastatic prostate cancer.

METHODS

An indirect comparison of Overall Survival (OS) and time to PSA progression among abiraterone acetate, enzalutamide, cabazitaxel and Radium-223 was performed with a network metaanalysis. OS in the entire population of patients was the primary endpoint. OS in ECOG 0-1/2, BPISF≤ 4/>4, pretreated with 1 or 2 courses of chemotherapy, age≤65/>65 patients, patients with only bone metastases or bone and visceral metastases, and time to PSA progression were the secondary endpoints. An indirect comparison of the Hazard Ratio and the 95% Confidence Interval was performed, assuming an alpha error of 5% as an index of statistical significance. The among-the-trial heterogeneity was assessed using a qualitative methodological and clinical analysis.

RESULTS

Four trials were selected. In three trials, the comparator was placebo, in one trial it was mitoxantrone, the effect of which in improving survival was considered negligible. No significant difference in OS among abiraterone acetate, enzalutamide, cabazitaxel and radium 223 was observed in neither the entire population nor all the subgroups of patients. Enzalutamide resulted significantly better than abiraterone acetate, cabazitaxel or radium-223 in time to PSA progression.

CONCLUSION

Since no significant difference in efficacy seems to exist between the four therapeutic options in the treatment of castration-resistant, docetaxel-resistant, metastatic prostate cancer, the safety of the treatment, patient's compliance and costs should represent the criteria to guide clinicians' choice in clinical practice.

Synaptophysin expression on circulating tumor cells in patients with castration resistant prostate cancer undergoing treatment with abiraterone acetate or enzalutamide

BACKGROUND

With the advent of secondary androgen receptor (AR)-targeted therapies in metastatic castration resistant prostate cancer (PC), nonadenocarcinoma PCs are becoming more prevalent. Many of these cancers express neuroendocrine markers, which may provide biomarkers for emergence of this disease state. We aimed to quantify the expression of synaptophysin (Syp) on circulating tumor cells (CTCs) from serial samples of patients being treated with abiraterone acetate or enzalutamide.

METHODS

CTCs were isolated from 44 patients with castration resistant PC before starting abiraterone or enzalutamide, at 4, 8, and 12 weeks on therapy, and at progression. Patients were stratified into 3 groups: de novo resistance, short response, and long response. CTCs were enumerated on the CellSearch platform and Syp expression was quantified using the open fluorescent channel on the platform. Correlative analyses were performed.

RESULTS

A baseline CTC count of 5 or greater was associated with a more rapid time to progression and increasing CTC counts correlated with emergence of drug resistance. Syp was readily detectable on the surface of CTCs, and baseline percentage CTC Syp expression was significantly associated with time to progression. Furthermore, in evaluable patients, percent CTC Syp expression increased with the emergence of drug resistance. We also found that prior exposure to AR-targeted therapies was inversely associated with progression free survival.

CONCLUSIONS

We have demonstrated that Syp can be quantified on CTCs and that Syp expression correlates with resistance to abiraterone and enzalutamide. Larger studies testing Syp as a biomarker of emergence of nonadenocarcinoma disease and as a marker of response to AR-targeted therapies are warranted.

[A Case of Fulminant Hepatitis after Administration of Abiraterone Acetate]

A 77-year-old man with castration-resistant prostate cancer (CRPC) received abiraterone acetate in October 2014. He visited our outpatient clinic because of general malaise and anorexia 27 days after starting abiraterone acetate. The lab test showed hepatic dysfunction (aspartate transaminase, AST 440 U/l, alanine transaminase, ALT 420 U/l) and the elevation of liver enzymes continued on the next day even after stopping abiraterone acetate. Three days later, he was hospitalized due to severe elevation of liver enzymes (AST 1,171 U/l, ALT 1,487 U/l) , and the decreased prothrombin activity (60.5%). The result of the lab test were negative for viral and autoimmune hepatitis. Three days after admission, he entered hepatic coma (grade III) and prothrombin activity decreased (23.2%) , compatible with fulminant hepatitis. Plasma exchange and steroid pulse therapy were started the next day, but he died 39 days after starting abiraterone acetate. In addition, the result of drug-induced lymphocyte stimulation test performed 3 days before his death was possibly positive.

Testicular vs adrenal sources of hydroxy-androgens in prostate cancer

Neoadjuvant androgen deprivation therapy (NADT) is one strategy for the treatment of early-stage prostate cancer; however, the long-term outcomes of NADT with radical prostatectomy including biochemical failure-free survival are not promising. One proposed mechanism is incomplete androgen ablation. In this study, we aimed to evaluate the efficiency of serum hydroxy-androgen suppression in patients with localized high-risk prostate cancer under NADT (leuprolide acetate plus abiraterone acetate and prednisone) and interrogate the primary sources of circulating hydroxy-androgens using our recently described stable isotope dilution liquid chromatography mass spectrometric method. For the first time, three androgen diols including 5-androstene-3β,17β-diol (5-adiol), 5α-androstane-3α,17β-diol (3α-adiol), 5α-androstane-3β,17β-diol (3β-adiol), the glucuronide or sulfate conjugate of 5-adiol and 3α-adiol were measured and observed to be dramatically reduced after NADT. By comparing patients that took leuprolide acetate alone vs leuprolide acetate plus abiraterone acetate and prednisone, we were able to distinguish the primary sources of these androgens and their conjugates as being of either testicular or adrenal in origin. We find that testosterone, 5α-dihydrotestosterone (DHT), 3α-adiol and 3β-adiol were predominately of testicular origin. By contrast, dehydroepiandrosterone (DHEA), epi-androsterone (epi-AST) and their conjugates, 5-adiol sulfate and glucuronide were predominately of adrenal origin. Our findings also show that NADT failed to completely suppress DHEA-sulfate levels and that two unappreciated sources of intratumoral androgens that were not suppressed by leuprolide acetate alone were 5-adiol-sulfate and epi-AST-sulfate of adrenal origin.

Redefining Hormonal Therapy for Advanced Prostate Cancer: Results from the LATITUDE and STAMPEDE Studies

Two papers published recently in the New England Journal of Medicine describe the utility of abiraterone acetate, an androgen biosynthesis inhibitor, in the early treatment of metastatic prostate cancer. In addition to establishing a new standard of care, these two articles pose a number of important questions for future investigation.

Predictors of duration of abiraterone acetate in men with castration-resistant prostate cancer

BACKGROUND

Androgen receptor signaling remains important in castration-resistant prostate cancer (CRPC) as demonstrated by the efficacy of abiraterone acetate (henceforth abiraterone) in phase III trials. Given that heterogeneous patient responses are observed, we sought to identify clinical factors associated with duration of abiraterone.

METHODS

We retrospectively identified patients with CRPC treated with abiraterone in our database. Patient characteristics and types and duration of prostate cancer (PC) therapies were analyzed. These parameters were analyzed with duration of abiraterone in univariate and multivariable analyses.

RESULTS

We identified 161 patients who had received abiraterone. All had received primary androgen-deprivation therapy (ADT), 86% prior secondary hormone therapy (SHT) and 33% prior chemotherapy. The median duration of primary ADT was 23 months, duration of SHT (excluding abiraterone) was 17 months and duration of chemotherapy was 8 months. We demonstrated that lower PSA at abiraterone initiation, longer primary ADT duration, no prior ketoconazole, no prior chemotherapy and longer chemotherapy duration were associated with a longer duration on abiraterone in univariate analysis. In multivariable analysis, duration of primary ADT (duration of abiraterone 9 versus 13 months for ⩽12 versus >12 months, P=0.03) and no use of prior chemotherapy (duration of abiraterone 16 versus 7 months for no versus yes prior chemotherapy, P<0.01) were associated with duration of abiraterone.

CONCLUSIONS

Several clinical parameters, including type and duration of prior therapy, are predictive of responsiveness to abiraterone. These parameters are logical and correlate with smaller disease burden or less exposure to PC therapies. This information can help physicians counsel patients about the potential durability of efficacy of abiraterone. Identifying predictive biomarkers that inform patient selection for therapy is critical to optimizing treatment outcomes.

Early Prediction of Therapy Response to Abiraterone Acetate Using PSA Subforms in Patients with Castration Resistant Prostate Cancer

The purpose of this study was to evaluate the prognostic ability of early changes of total prostate specific antigen (tPSA), free PSA (fPSA), [−2]proPSA and the Prostate Health Index (PHI) following initiation of Abiraterone-therapy in men with castration resistant prostate cancer (mCRPC). In 25 patients, PSA-subforms were analyzed before and at 8–12 weeks under therapy as prognosticators of progression-free-survival (PFS) and overall survival (OS). Comparing patients with a PFS < vs. ≥12 months by using Mann–Whitney–Wilcoxon Tests, the relative-median-change of tPSA (−0.1% vs. −86.8%; p = 0.02), fPSA (12.1% vs. −55.3%; p = 0.03) and [−2]proPSA (8.1% vs. −59.3%; p = 0.05) differed significantly. For men with ≤ vs. >15 months of OS there was a non-significant trend for a difference in the relative-median-change of fPSA (17.0% vs. −46.3%; p = 0.06). In Kaplan–Meier analyses, declining fPSA and [−2]proPSA were associated with a longer median PFS (13 months, 95% confidence interval (CI): 9.6–16.4 vs. 10 months, 95% CI: 3.5–16.5; p = 0.11), respectively. Correspondingly, decreasing fPSA and [−2]proPSA values indicated an OS of 32 months (95% CI: not reached (NR)) compared to 21 months in men with rising values (95% CI: 7.7–34.3; p = 0.14), respectively. We concluded that the addition of fPSA- and [−2]proPSA-changes to tPSA-information might be further studied as potential markers of early Abiraterone response in mCRPC patients.

Uncontrolled diabetes predicts poor response to novel antiandrogens

Metabolic abnormalities including hyperglycemia and hyperlipidemia have been associated with worse prognosis of prostate cancer (PCa), but there are limited data regarding their impact on the prognosis of castrate-resistant prostate cancer (CRPC) and the response of novel antiandrogens, namely abiraterone acetate (AA) and enzalutamide. Retrospective analysis of 61 patients with CRPC on AA or enzalutamide, treated at the Boston Medical Center, was performed. We evaluated hemoglobin A1c (HbA1c), HDL, LDL, Triglycerides and BMI within 2months before the initiation of treatment with AA or enzalutamide and progression-free survival (PFS) under this treatment. Regression analysis and analysis of variance were used to evaluate the data. HbA1c levels were found to predict adversely the PFS on the novel agents (df (1, 37), P=0.00, R(2)=0.40, coeff=-3.28). The Kaplan-Meier analysis showed that there is significant difference in survival between the HbA1c 4.7-5.9% compared with patients with HbA1c 7.8-11.6% (6.72±1.3months, log rank test P<0.0001) LDL (P=0.07), HDL (P=0.14), and triglycerides (P=0.33) were not found to predict PFS. BMI predicted PFS positively (df (1.59), P=0.02, R(2)=0.09, coeff=0.03), but not independently of HbA1c (P=0.07). No significant implications of social and family history, previous chemotherapy regimen, and Gleason score with PFS were found. Multiple markers of patients' health state were not associated with HbA1c values. Uncontrolled diabetes can predict for poor response of CRPC patients to AA and enzalutamide determining PFS under this treatment. Elevated BMI can positively affect PFS at this stage of disease.

Influence of Statins on Survival Outcome in Patients with Metastatic Castration Resistant Prostate Cancer Treated with Abiraterone Acetate

OBJECTIVE

Even though the exact mechanism is largely unknown until now, statins are supposed to improve survival outcomes in various malignancies. For prostate cancer however, statins are known to compete with dehydroepiandrosterone (DHEAS) for the transport into the cytosol both using the cell by the Solute Carrier Transporter and thus diminish the cellular uptake of DHEAS as a precursor of androgens. Abiraterone inhibits CYP17A1 and thus effectively decreases the production of all relevant androgens including DHEAS. In this study we examined whether statins still affect survival outcome in patients with metastatic castration resistant prostate cancer (mCRPC) when treated with Abiraterone.

PATIENTS AND METHODS

108 men with mCRPC treated with Abiraterone from 02/2010 to 07/2015 with (n = 21) or without (n = 87) concomitant treatment with statins were investigated. Progression free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier-estimates and univariate Cox-regression analysis. The influence on best clinical benefit under Abiraterone treatment was analyzed with bivariate and multivariate logistic regression analysis.

RESULTS

PSA-decline ≥ 50% was not significantly different in both groups (57 vs. 53%; p = 0.73). The median PFS (9 vs. 10 months; p = 0.97) and OS (14 vs. 18 months; p = 0.77) did not differ significantly between those men treated with and without concomitant statin therapy, respectively. Accordingly, there was no improvement for best clinical benefit in patients using statins (odds ratio: 1.2 (CI: 0.4-4.2); p = 0.76).

CONCLUSION

Use of statins as concomitant medication did not improve survival outcomes or best clinical benefit in men with mCRPC treated with Abiraterone.

Cost per median overall survival month associated with abiraterone acetate and enzalutamide for treatment of patients with metastatic castration-resistant prostate cancer

OBJECTIVE

To calculate costs per median overall survival (OS) month in chemotherapy-naïve patients with metastatic castration-resistant prostate cancer (mCRPC) treated with abiraterone acetate plus prednisone (AA + P) or enzalutamide.

METHODS

Median treatment duration and median OS data from published Phase 3 clinical trials and prescribing information were used to calculate costs per median OS month based on wholesale acquisition costs (WACs) for patients with mCRPC treated with AA + P or enzalutamide. Sensitivity analyses were performed to understand how variations in treatment duration and treatment-related monitoring recommendations influenced cost per median OS month. Cost-effectiveness estimates of other Phase 3 trial outcomes were also explored: cost per month of chemotherapy avoided and per median radiographic progression-free survival (rPFS) month.

RESULTS

The results demonstrated that AA + P has a lower cost per median OS month than enzalutamide ($3231 vs 4512; 28% reduction), based on the following assumptions: median treatment duration of 14 months for AA + P and 18 months for enzalutamide, median OS of 34.7 months for AA + P and 35.3 months for enzalutamide, and WAC per 30-day supply of $8007.17 for AA + P vs $8847.98 for enzalutamide. Sensitivity analyses showed that accounting for recommended treatment-related monitoring costs or assuming identical treatment durations for AA + P and enzalutamide (18 months) resulted in costs per median OS month 8-27% lower for AA + P than for enzalutamide. Costs per month of chemotherapy avoided were $4448 for AA + P and $5688 for enzalutamide, while costs per month to achieve median rPFS were $6794 for AA + P and $7963 for enzalutamide.

CONCLUSIONS

This cost-effectiveness analysis demonstrated that costs per median OS month, along with costs of other Phase 3 trial outcomes, were lower for AA + P than for enzalutamide. The findings were robust to sensitivity analyses. These results have important implications for population health decision-makers evaluating the relative value of therapies for mCRPC patients.

Impact of Prior Use of an Androgen Receptor-Axis-Targeted (ARAT) Agent With or Without Subsequent Taxane Therapy on the Efficacy of Another ARAT Agent in Patients With Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

The objective of this study was to investigate whether the prior use of a novel androgen receptor-axis-targeted (ARAT) agent with or without subsequent taxane therapy could affect the efficacy of another ARAT agent in patients with metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

This study included a total of 302 patients with mCRPC, who were treated with abiraterone acetate and/or enzalutamide. These 302 patients were classified into the following 3 groups: group A, 173 received an ARAT agent without the prior use of another ARAT agent; group B, 102 sequentially received ARAT agents without any treatment between the 2 agents; group C, 27 sequentially received ARAT agents, with taxane therapy between the 2 ARAT agents.

RESULTS

The response rate to the ARAT agent in group A (63.6%) was significantly higher than those to the ARAT agent introduced late-line in groups B and C (20.6% and 29.6%, respectively). In addition, prostate-specific antigen progression-free survival during the ARAT therapy in group A was significantly superior to those during the ARAT therapy conducted late-line in groups B and C. Multivariate analyses of several parameters identified the prior use of an ARAT agent, but not the administration of taxane between the ARAT therapies, as one of the independent predictors of prostate-specific antigen progression-free survival.

CONCLUSIONS

Cross-resistance between ARAT agents may be a common phenomenon in patients with mCRPC, irrespective of the introduction of taxane between the ARAT therapies.

Association of early PSA decline and time to PSA progression in abiraterone acetate-treated metastatic castration-resistant prostate cancer; a post-hoc analysis of Japanese phase 2 trials

BACKGROUND

Previous studies have demonstrated an association between prostate-specific antigen (PSA) kinetics and predictive value for treatment outcomes. Abiraterone acetate (AA) is a newly approved cytochrome-P450C17 inhibitor for treatment of metastatic castration-resistant prostate cancer (mCRPC), and few studies have evaluated PSA kinetics using AA so far. Results of a study evaluating PSA kinetics in the beginning of AA and enzalutamide responded chemotherapy-treated patients suggested different trends between the drugs. PSA kinetics of AA-treated patients has been reported using large datasets; however, no studies which have fully evaluated PSA kinetics in the beginning treatment. The present study aimed to assess the PSA kinetics and relationship between the PSA kinetics and PSA progression in chemotherapy-naïve and chemotherapy-treated mCRPC patients receiving AA.

METHODS

We used two Japanese phase II trial datasets: JPN-201, chemotherapy-naïve mCRPC (n = 48) and JPN-202, chemotherapy-treated mCRPC (n = 46). PSA kinetic parameters were calculated using actual PSA values measured every 4 weeks, and a subgroup analysis was performed to evaluate the influence of early PSA response on time to PSA progression (TTPP). In addition, we used a Cox proportional hazard model to investigate the influence of variables on TTPP.

RESULTS

PSA declined from week 4 but took more time to achieve nadir. PSA kinetic parameters were different between the datasets, mean time to PSA nadir was 5.3 ± 5.6 and 2.0 ± 3.4 months, and TTPP was 9.5 ± 7.4 and 3.8 ± 4.8 months in JPN-201 and JPN-202, respectively. In the subgroup analysis of week 4 PSA decline status, Kaplan-Meier curves for TTPP were similar between early responders and non-progression patients in JPN-201 (median, 9.2 vs. 6.5 months, respectively) but separated in JPN-202 (median, 3.7 vs. 1.9 months, respectively). According to univariate Cox regression analysis, achievement of PSA response (≥50 %) at week 12 was associated with TTPP in the both trials, but the hazard ratio of PSA decline (≥30 %) at week 4 was not significant in JPN-201.

CONCLUSIONS

Our results suggest that PSA kinetics were not comparable and early PSA response showed different association to TTPP according to prior history of chemotherapy.

TRIAL REGISTRATION

The original trials are registered at ClinicalTrials.gov. The identifiers are; JNJ-212082-JPN-201 , registered 20 December 2012 and JNJ-212082-JPN-202 , registered 30January 2013.

Influence of abiraterone acetate on circulating neuromediators in chemotherapy-naïve castration-resistant prostate cancer

BACKGROUND

Abiraterone Acetate (AA) represents a highly effective androgen-receptor (AR) axis targeted agent. Treatment with AA in castration-resistant prostate cancer (CRPC) may partly mediate neuroendocrine differentiation (NED) as an escape mechanism, which may have implications for the choice of sequential therapy in CRPC. We evaluated how treatment with AA influences circulating neuromediators chromogranin A (CGA), neuron-specific enolase (NSE), and pro-gastrin-releasing peptide (Pro-GRP) in chemotherapy-naïve CRPC patients.

METHODS

We conducted an analysis in chemotherapy-naïve CRPC patients with clinical or radiographic progression of disease. A total of 35 patients were included at five institutions between February 2013 and December 2014. Sixteen of them had received AA. Serum samples were obtained before a docetaxel-based chemotherapy and analyzed in a reference laboratory. Univariable and multivariable analyses were performed to test the influence of AA treatment, its duration of treatment, and other clinicopathological variables on circulating neuromediators.

RESULTS

CGA and NSE levels were above the upper limit of normal (ULN) in n = 20 (57.1%) and n = 13 (37.1%), respectively. Treatment with AA and duration of treatment were not associated with levels above the ULN (CGA and NSE) or higher levels (Pro-GRP) of neuromediators. CGA levels were associated with age (P = 0.092), lymph node metastasis (P = 0.014), duration of androgen deprivation therapy (ADT; P = 0.083), and intake of proton pump inhibitors (P = 0.069). Pro-GRP levels were significantly associated with PSA levels (P = 0.002). On multivariate analysis, CGA levels above the ULN were significantly correlated with ADT (P = 0.01) and intake of proton pump inhibitors (P = 0.03).

CONCLUSIONS

Circulating neuromediators in chemotherapy-naïve CRPC patients were elevated in a high percentage of patients. ADT was found to be a relevant NED driver in this cohort. Our results may imply that patients with CRPC after first-line treatment with AA in CRPC are not at a higher risk for developing NED. The major limitation of the study represents the one-time analysis of neuromediators. Larger studies with serial blood measurements or biopsy analysis before and after treatment are needed to confirm our results.

A prognostic index model for predicting overall survival in patients with metastatic castration-resistant prostate cancer treated with abiraterone acetate after docetaxel

A prognostic index model was developed, composed of six readily available and assessable factors and categorizing patients with metastatic castration-resistant prostate cancer treated with abiraterone–prednisone into distinct prognostic risk groups. This model could be useful for determining patient prognosis for follow-up, monitoring and patient stratification for clinical trials.

Background

Few prognostic models for overall survival (OS) are available for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with recently approved agents. We developed a prognostic index model using readily available clinical and laboratory factors from a phase III trial of abiraterone acetate (hereafter abiraterone) in combination with prednisone in post-docetaxel mCRPC.

Patients and methods

Baseline data were available from 762 patients treated with abiraterone–prednisone. Factors were assessed for association with OS through a univariate Cox model and used in a multivariate Cox model with a stepwise procedure to identify those of significance. Data were validated using an independent, external, population-based cohort.

Results

Six risk factors individually associated with poor prognosis were included in the final model: lactate dehydrogenase > upper limit of normal (ULN) [hazard ratio (HR) = 2.31], Eastern Cooperative Oncology Group performance status of 2 (HR = 2.19), presence of liver metastases (HR = 2.00), albumin ≤4 g/dl (HR = 1.54), alkaline phosphatase > ULN (HR = 1.38) and time from start of initial androgen-deprivation therapy to start of treatment ≤36 months (HR = 1.30). Patients were categorized into good (n = 369, 46%), intermediate (n = 321, 40%) and poor (n = 107, 13%) prognosis groups based on the number of risk factors and relative HRs. The C-index was 0.70 ± 0.014. The model was validated by the external dataset (n = 286).

Conclusion

This analysis identified six factors used to model survival in mCRPC and categorized patients into three distinct risk groups. Prognostic stratification with this model could assist clinical practice decisions for follow-up and monitoring, and may aid in clinical trial design.

Trial registration numbers

NCT00638690.

Impact of bone-targeted therapies in chemotherapy-naïve metastatic castration-resistant prostate cancer patients treated with abiraterone acetate: post hoc analysis of study COU-AA-302

BACKGROUND

Metastatic castration-resistant prostate cancer (mCRPC) often involves bone, and bone-targeted therapy (BTT) has become part of the overall treatment strategy.

OBJECTIVE

Investigation of outcomes for concomitant BTT in a post hoc analysis of the COU-AA-302 trial, which demonstrated an overall clinical benefit of abiraterone acetate (AA) plus prednisone over placebo plus prednisone in asymptomatic or mildly symptomatic chemotherapy-naïve mCRPC patients.

DESIGN, SETTING, AND PARTICIPANTS

This report describes the third interim analysis (prespecified at 55% overall survival [OS] events) for the COU-AA-302 trial.

INTERVENTION

Patients were grouped by concomitant BTT use or no BTT use.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Radiographic progression-free survival and OS were coprimary end points. This report describes the third interim analysis (prespecified at 55% OS events) and involves patients treated with or without concomitant BTT during the COU-AA-302 study. Median follow-up for OS was 27.1 mo. Median time-to-event variables with 95% confidence intervals (CIs) were estimated using the Kaplan-Meier method. Adjusted hazard ratios (HRs), 95% CIs, and p values for concomitant BTT versus no BTT were obtained via Cox models.

RESULTS AND LIMITATIONS

While the post hoc nature of the analysis is a limitation, superiority of AA and prednisone versus prednisone alone was demonstrated for clinical outcomes with or without BTT use. Compared with no BTT use, concomitant BTT significantly improved OS (HR 0.75; p=0.01) and increased the time to ECOG deterioration (HR 0.75; p<0.001) and time to opiate use for cancer-related pain (HR 0.80; p=0.036). The safety profile of concomitant BTT with AA was similar to that reported for AA in the overall intent-to-treat population. Osteonecrosis of the jaw (all grade 1/2) with concomitant BTT use was reported in <3% of patients.

CONCLUSIONS

AA with concomitant BTT was safe and well tolerated in men with chemotherapy-naïve mCRPC. The benefits of AA on clinical outcomes were increased with concomitant BTT.

PATIENT SUMMARY

Treatment of advanced prostate cancer often includes bone-targeted therapy. This post hoc analysis showed that in patients with advanced prostate cancer who were treated with abiraterone acetate and prednisone in combination with bone-targeted therapy, there was a continued trend in prolongation of life when compared with patients treated with prednisone alone.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00887198.

ODM-201: a new-generation androgen receptor inhibitor in castration-resistant prostate cancer

Androgen deprivation therapy is the standard of care for patients with advanced hormone-sensitive prostate cancer. Despite an initial response, most patients progress to castration-resistant prostate cancer (CRPC). The realization that CRPC remains driven by androgen receptor (AR) signaling has formed the basis for a new generation of agents targeting the AR axis. Two of these agents, abiraterone acetate and enzalutamide, have been shown to prolong overall survival in patients with CRPC. Several other AR inhibitors are currently in development for the treatment of CRPC. The present article reviews ODM-201, a new-generation AR inhibitor with a unique molecular structure, in the treatment of CRPC. The design of an ongoing Phase III trial (ARAMIS) of ODM-201 in men with non-metastatic CRPC is also discussed, at a disease stage for which there is currently no approved treatment.