Abiraterone acetate: targeting persistent androgen dependence in castration-resistant prostate cancer.
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ABSTRACT:
SUBMITTER: Harshman LC
PROVIDER: S-EPMC3778906 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The treatment of castration-resistant (CR) prostate cancer (PCa) is limited. A sub-population of CR PCa tumors can synthesize androgens for intracrine androgen receptor (AR) activation, thus targeting androgen biosynthesis could be an effective therapeutic option for these patients. We determined that androgen biosynthesis inhibitors simvastatin, atorvastatin, and ketoconazole directly inhibit growth, migration, and colony formation of LNCaP C-81 cells, which exhibit de novo androgen biosynthesis, with simvastatin being the most effective. Importantly, in combination treatments, statins specifically enhanced growth suppression with added effects by anti-androgen abiraterone acetate on the CR PCa cells. Thus, statins can be used in conjunction with abiraterone acetate to enhance anti-androgen therapy for CR PCa.
| S-EPMC6641547 | biostudies-literature
Project description:PurposeMetastatic castration-resistant prostate cancer (mCRPC) remains a lethal disease with current standard-of-care therapies. Homologous recombination repair (HRR) gene alterations, including BRCA1/2 alterations, can sensitize cancer cells to poly (ADP-ribose) polymerase inhibition, which may improve outcomes in treatment-naïve mCRPC when combined with androgen receptor signaling inhibition.MethodsMAGNITUDE (ClinicalTrials.gov identifier: NCT03748641) is a phase III, randomized, double-blinded study that evaluates niraparib and abiraterone acetate plus prednisone (niraparib + AAP) in patients with (HRR+, n = 423) or without (HRR-, n = 247) HRR-associated gene alterations, as prospectively determined by tissue/plasma-based assays. Patients were assigned 1:1 to receive niraparib + AAP or placebo + AAP. The primary end point, radiographic progression-free survival (rPFS) assessed by central review, was evaluated first in the BRCA1/2 subgroup and then in the full HRR+ cohort, with secondary end points analyzed for the full HRR+ cohort if rPFS was statistically significant. A futility analysis was preplanned in the HRR- cohort.ResultsMedian rPFS in the BRCA1/2 subgroup was significantly longer in the niraparib + AAP group compared with the placebo + AAP group (16.6 v 10.9 months; hazard ratio [HR], 0.53; 95% CI, 0.36 to 0.79; P = .001). In the overall HRR+ cohort, rPFS was significantly longer in the niraparib + AAP group compared with the placebo + AAP group (16.5 v 13.7 months; HR, 0.73; 95% CI, 0.56 to 0.96; P = .022). These findings were supported by improvement in the secondary end points of time to symptomatic progression and time to initiation of cytotoxic chemotherapy. In the HRR- cohort, futility was declared per the prespecified criteria. Treatment with niraparib + AAP was tolerable, with anemia and hypertension as the most reported grade ≥ 3 adverse events.ConclusionCombination treatment with niraparib + AAP significantly lengthened rPFS in patients with HRR+ mCRPC compared with standard-of-care AAP.[Media: see text].
| S-EPMC10431499 | biostudies-literature
Project description:Abiraterone acetate, a prodrug of the CYP17A1 inhibitor abiraterone that blocks androgen biosynthesis, is approved for treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) in combination with prednisone or prednisolone 5 mg twice daily. This review evaluates the basis for the effects of prednisone on mineralocorticoid-related adverse events that arise because of CYP17A1 inhibition with abiraterone. Coadministration with the recommended dose of glucocorticoid compensates for abiraterone-induced reductions in serum cortisol and blocks the compensatory increase in adrenocorticotropic hormone seen with abiraterone. Consequently, 5 mg prednisone twice daily serves as a glucocorticoid replacement therapy when coadministered with abiraterone acetate, analogous to use of glucocorticoid replacement therapy for certain endocrine disorders. We searched PubMed to identify safety concerns regarding glucocorticoid use, placing a focus on longitudinal studies in autoimmune and inflammatory diseases and cancer. In general, glucocorticoid-related adverse events, including bone loss, immunosuppression, hyperglycemia, mood and cognitive alterations, and myopathy, appear dose related and tend to occur at doses and/or treatment durations greater than the low dose of glucocorticoid approved in combination with abiraterone acetate for the treatment of mCRPC. Although glucocorticoids are often used to manage tumor-related symptoms or to prevent treatment-related toxicity, available evidence suggests that prednisone and dexamethasone might also offer modest therapeutic benefit in mCRPC. Given recent improvements in survival achieved for mCRPC with novel agents in combination with prednisone, the risks of these recommended glucocorticoid doses must be balanced with the benefits shown for these regimens.
| S-EPMC4257741 | biostudies-literature
Project description:It is now understood that persistent activation of the androgen receptor (AR) signaling pathway often underlies the development of castration-resistant prostate cancer (CRPC). This realization led to renewed interest in targeting the AR and ultimately to the development of the potent next-generation AR-directed agents abiraterone and enzalutamide. While these drugs prolong survival in men with CRPC, they are unfortunately not curative. Perhaps not surprisingly, evidence points to persistent AR signaling as one of the key drivers by which resistances to these agents develops. In this context, activation of the AR signaling program can occur through a number of molecular adaptations, including alterations leading to persistent canonical AR signaling (e.g., AR amplification/overexpression, elucidations/concentration of intratumoral androgens), activation of the AR program via feedback pathways (e.g., AKT/mTOR/Pi3K, HER2/Neu), and activation of the AR program via mutation or substitution (e.g., AR ligand binding domain mutation; AR splice variants; glucocorticoid receptor signaling). This review will provide an overview of the more clinical relevant (i.e., druggable) pathways that have been implicated in the emergence of drug resistance in men with CRPC and highlight some of the ongoing efforts towards developing therapeutics to impair these mechanisms.
| S-EPMC4644296 | biostudies-literature
Project description:BackgroundThe unmet need for predictive biomarkers emerged from the unpredictable pattern of response to androgen signalling inhibition in metastatic castration-resistant prostate cancer (mCRPC). Here, we report on the testing of a previously identified candidate androgen signalling signature associated with response to androgen signalling inhibition.Patients and methodsWe report on the outcome of the first module of a phase II trial on abiraterone acetate (AA) followed by combination with dasatinib or sunitinib. Bone marrow biopsies (BMBs) with matched bone marrow aspirate and blood samples were collected at baseline and upon progression. End-points included assessment of a prespecified molecular signature consisting of nuclear androgen receptor (AR) overexpression, cytochrome P450, family 17, subfamily A, polypeptide 1 (CYP17) expression, and AR-C-/N terminal expression ratio of ?0.8 by immunohistochemistry (IHC) in patients with benefit versus primary resistance to AA (i.e. progression within 4 months). Tumour markers also included v-ets avian erythroblastosis virus E26 oncogene homologue (ERG), androgen receptor splice variant (ARV7) by IHC and steroids by liquid chromatography-tandem mass spectrometry.ResultsOf 170 patients accrued from 03/2011 to 02/2015, 44 (26%) were primary resistant to AA. Forty-eight patients had tumour infiltrated BMB at baseline. Pretreatment androgen signalling signature was linked to benefit from AA (p < 0.001). Presence of ERG was associated with benefit (p = 0.05), whereas nuclear ARV7 presence and 20 or more bone lesions at baseline with primary resistance (p = 0.04 and p = 0.0006, respectively).ConclusionTesting of a prespecified androgen signalling signature was highly supportive of its predictive value in maximal androgen deprivation strategies in mCRPC. Further validation is under way.Trial registrationClinicalTrials.gov NCT01254864.
| S-EPMC7350510 | biostudies-literature
Project description:Androgen receptor (AR) splice variants (SV) have been implicated in the development of metastatic castration-resistant prostate cancer and resistance to AR targeting therapies, including abiraterone and enzalutamide. Agents targeting AR-SV are urgently needed to test this hypothesis and further improve the outcome of patients suffering from this lethal disease. Clin Cancer Res; 22(17); 4280-2. ©2016 AACRSee related article by Yang et al., p. 4466.
| S-EPMC5302169 | biostudies-literature
Project description:BACKGROUND:It is hypothesised that cotargeting the androgen receptor (AR) and paracrine androgen biosynthesis with enzalutamide and abiraterone acetate in metastatic castration-resistant prostate cancer (mCRPC) will dissipate adaptive feedback loops observed with either agent alone. OBJECTIVE:To assess the safety, efficacy, androgen signalling/metabolome, and drug-drug interactions (DDIs) of enzalutamide with abiraterone acetate in progressive bone mCRPC (bmCRPC). DESIGN, SETTING, AND PARTICIPANTS:This open-label, single-centre interventional study was conducted in bmCRPC patients. INTERVENTION:Enzalutamide 160mg and abiraterone acetate 1000mg once daily; prednisone 5mg twice daily. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS:Adverse events (AEs), prostate-specific antigen (PSA) response, progression-free survival (PFS), tumour biomarker/metabolite expression, and Cmin plasma concentrations were evaluated. RESULTS AND LIMITATIONS:Sixty patients were enrolled. Common AEs independent of grade/causality included fatigue (72%), hyperglycaemia (67%), alkaline phosphatase (ALP) elevation (53%), and hot flush (43%). Grade 3 AEs included hypertension (17%), alanine aminotransferase elevation (12%), ALP elevation (5%), and arthralgia (5%). No treatment-related grade 4 AEs or deaths were reported. Median treatment-discontinuation time was 312d (95% confidence interval [CI] 196.0-483.0). Maximal PSA decline ?50% and ?90% occurred in 46 (77%) and 29 (48%) patients, respectively. Median PFS was 251d (95% CI 147-337). At week 9, median tumour microenvironment androgens, precursors, and nuclear AR expression decreased (p<0.001). The baseline tumour AR C/N terminal ratio of ?80% was associated with treatment benefit. At enzalutamide steady state, abiraterone acetate Cmin was ?23% lower (range 14.05-200.5ng/ml) than when given alone. CONCLUSIONS:Enzalutamide combined with abiraterone acetate has a manageable safety profile, without a meaningful DDI. Both agents are pharmacodynamically active with no feedback. Efficacy findings do not support significant benefit of combined treatment for unselected bmCRPC. PATIENT SUMMARY:This is the first study combining enzalutamide plus abiraterone in bone metastatic castration-resistant prostate cancer. Results show that this combination is safe.
| S-EPMC7204265 | biostudies-literature
Project description:PurposeThe CYP17A1 inhibitor abiraterone markedly reduces androgen precursors and is thereby effective in castration-resistant prostate cancer (CRPC). However, abiraterone increases progesterone, which can activate certain mutant androgen receptors (AR) identified previously in flutamide-resistant tumors. Therefore, we sought to determine if CYP17A1 inhibitor treatment selects for progesterone-activated mutant ARs.Experimental designAR was examined by targeted sequencing in metastatic tumor biopsies from 18 patients with CRPC who were progressing on a CYP17A1 inhibitor (17 on abiraterone, 1 on ketoconazole), alone or in combination with dutasteride, and by whole-exome sequencing in residual tumor in one patient treated with neoadjuvant leuprolide plus abiraterone.ResultsThe progesterone-activated T878A-mutant AR was present at high allele frequency in 3 of the 18 CRPC cases. It was also present in one focus of resistant tumor in the neoadjuvant-treated patient, but not in a second clonally related resistant focus that instead had lost one copy of PTEN and both copies of CHD1. The T878A mutation appeared to be less common in the subset of patients with CRPC treated with abiraterone plus dutasteride, and transfection studies showed that dutasteride was a more potent direct antagonist of the T878A versus the wild-type AR.ConclusionsThese findings indicate that selection for tumor cells expressing progesterone-activated mutant ARs is a mechanism of resistance to CYP17A1 inhibition.
| S-EPMC4359958 | biostudies-literature
Project description:PurposePersistent androgen signaling is implicated in castrate-resistant prostate cancer (CRPC) progression. This study aimed to evaluate androgen signaling in bone marrow-infiltrating cancer and testosterone in blood and bone marrow and to correlate with clinical observations.Patients and methodsThis was an open-label, observational study of 57 patients with bone-metastatic CRPC who underwent transiliac bone marrow biopsy between October 2007 and March 2010. Patients received oral abiraterone acetate (1 g) once daily and prednisone (5 mg) twice daily. Androgen receptor (AR) and CYP17 expression were assessed by immunohistochemistry, testosterone concentration by mass spectrometry, AR copy number by polymerase chain reaction, and TMPRSS2-ERG status by fluorescent in situ hybridization in available tissues.ResultsMedian overall survival was 555 days (95% CI, 440 to 965+ days). Maximal prostate-specific antigen decline ≥ 50% occurred in 28 (50%) of 56 patients. Homogeneous, intense nuclear expression of AR, combined with ≥ 10% CYP17 tumor expression, was correlated with longer time to treatment discontinuation (> 4 months) in 25 patients with tumor-infiltrated bone marrow samples. Pretreatment CYP17 tumor expression ≥ 10% was correlated with increased bone marrow aspirate testosterone. Blood and bone marrow aspirate testosterone concentrations declined to less than picograms-per-milliliter levels and remained suppressed at progression.ConclusionThe observed pretreatment androgen-signaling signature is consistent with persistent androgen signaling in CRPC bone metastases. This is the first evidence that abiraterone acetate achieves sustained suppression of testosterone in both blood and bone marrow aspirate to less than picograms-per-milliliter levels. Potential admixture of blood with bone marrow aspirate limits our ability to determine the origin of measured testosterone.
| S-EPMC3295561 | biostudies-literature
Project description:The androgen receptor (AR) is a ligand-inducible transcription factor that mediates androgen action in target tissues. Upon ligand binding, the AR binds to thousands of genomic loci and activates a cell-type specific gene program. Prostate cancer growth and progression depend on androgen-induced AR signaling. Treatment of advanced prostate cancer through medical or surgical castration leads to initial response and durable remission, but resistance inevitably develops. In castration-resistant prostate cancer (CRPC), AR activity remains critical for tumor growth despite androgen deprivation. Although previous studies have focused on ligand-dependent AR signaling, in this study we explore AR function under the androgen-deprived conditions characteristic of CRPC. Our data demonstrate that AR persistently occupies a distinct set of genomic loci after androgen deprivation in CRPC. These androgen-independent AR occupied regions have constitutively open chromatin structures that lack the canonical androgen response element and are independent of FoxA1, a transcription factor involved in ligand-dependent AR targeting. Many AR binding events occur at proximal promoters, which can act as enhancers to augment transcriptional activities of other promoters through DNA looping. We further show that androgen-independent AR binding directs a gene expression program in CRPC, which is necessary for the growth of CRPC after androgen withdrawal.
| S-EPMC3510497 | biostudies-literature