Prostate-specific Antigen Response Rate Research Articles

Clinical Effect of Switching from a Luteinizing Hormone-Releasing Hormone Agonist to an Antagonist in Patients with Castration-Resistant Prostate Cancer and Serum Testosterone Level ≥ 20 ng/dl

Introduction: The efficacy of conversion from a luteinizing hormone-releasing hormone agonist to an antagonist was evaluated prospectively in patients with castration-resistant prostate cancer. Materials and Methods: From October 2012 to December 2014, 8 cases with a serum testosterone level ≥ 20 ng/dl during following androgen deprivation therapy were enrolled and received degarelix monthly. The primary end-pointgoal was to determine the effective prostate-specific antigen response rate. The secondary end-pointgoal was to assess the proportion of cases with a decrease in serum testosterone level to < 20 ng/ml. Results: One patient achieved a complete response, with a prostate-specific antigen level of 0.02 ng/ml at the nadirend of the study. The effective response rate was 25.0% (2/8), and the proportion of cases with prostate-specific antigen decline was 62.5% (5/8). In 5/8 cases (5/8, 62.5%), serum testosterone levels declined to < 20 ng/dl. Conclusion: Switching to a luteinizing hormone-releasing hormone antagonist in patients with testosterone levels ≥ 20 ng/dl may be an option in sequential androgen deprivation therapy for some patients.

The role of fPSA, [-2]proPSA and the Prostate Health Index for the early prediction of outcome in patients with metastatic castration resistant prostate cancer on therapy with abirateroneacetate.

241 Background: Abiraterone acetate (AA) prolongs overall survival (OS) in pre- and post-chemotherapy setting in patients with metastatic castration resistant prostate cancer (mCRPC). Biomarkers to predict response to therapy are limited. Prostate-specific antigen (PSA) and lactate dehydrogenase (LDH) are commonly used as response-indicators but are often misleading during early therapy. Assays for circulating tumor cells, which can be surrogate for poor survival, are not routinely available at most places. In this retrospective study we evaluated the role of the PSA-derivatives free PSA (fPSA), [-2]proPSA (p2PSA) and the prostate health index (PHI) in addition to PSA as indicators of response during early AA-therapy. Methods: Twenty-five men with mCRPC receiving AA between March 2012 and July 2015 at the University Hospital of Muenster were included and analyzed. The PSA response rate (RR) was monitored according to PCWG2-criteria. Dynamic PSA-, fPSA-, p2PSA- and PHI-changes at 8-12 weeks under therapy were analyzed as predictors of progression free survival (PFS) and OS using Kaplan-Meier-analysis (KMA) and uni- and multivariate cox-regression analysis (UVA and MVA). Results: Twenty men were chemotherapy naïve, 5 pretreated with docetaxel. The PSA RR was 44%. In patients with &lt; or ≥ 12 months of PFS the relative change of median PSA and fPSA at 8-12 weeks compared to baseline differed significantly (p = 0.022 and 0.030). For men with ≤ or &gt; 15 months of OS there was a trend for a difference in relative change of median fPSA (p = 0.058). In KMA declining fPSA at 8-12 weeks was associated with a median OS of 32 months compared to 21 months in men with rising fPSA. In UVA rising PSA and fPSA were non-significant predictors of poor OS (Hazard ratio (HR) = 1.3 and 2.5 (p = 0.717 and 0.159)). In MVA PSA and fPSA were independent predictors of poor survival (HR 6.7 and 12.8 (p = 0.050 and 0.012)). Conclusions: fPSA is easily available and cheap. When added to PSA information, change of fPSA at 8-12 weeks of AA therapy may be a promising therapy control marker to help physicians to make decisions weather to stop or to continue AA therapy in men with mCRPC.

A randomized trial of abiraterone acetate (AA) administered with 1 of 4 glucocorticoid (GC) regimens in metastatic castration-resistant prostate cancer (mCRPC) patients (pts).

261 Background: AA is approved for mCRPC, coadministered with prednisone (P) (5 mg BID) to prevent adverse events (AEs) associated with mineralocorticoid excess (ME). Lower GC doses had not previously been formally evaluated in combination with AA. Methods: This was an open-label, multicenter, phase 2 trial (NCT01867710) of asymptomatic chemotherapy-naïve mCRPC pts randomized 1:1:1:1 to AA (1000 mg QD) plus P 5 mg BID or P 5 mg QD or P 2.5 mg BID or dexamethasone (DEX) 0.5 mg QD. Pts who had previously received GC or ketoconazole were excluded. The primary end point was no ME (% of pts experiencing neither hypokalemia nor hypertension during the first 24 weeks of treatment).Secondary end points included additional safety, as well as response rate in the first 24 weeks, defined as a decline in prostate-specific antigen (PSA) ≥ 50% confirmed after 4 weeks. Results: 164 pts were randomized; 133 (81.6%) completed 24 weeks’ treatment. Median age: 70 years. Table 1 shows the rates of ME, hypertension, hypokalemia and PSA response. Changes in HbA1c values were minimal and observed in 16 (10.7%) pts. Conclusions: These data suggest that P 5 mg BID, which is approved in combination with AA, and DEX 0.5 mg QD, are effective in preventing ME-associated AEs, and that P 2.5 mg BID and P 5 mg QD can be safely used with appropriate monitoring. The suggestion of a higher PSA response rate with DEX 0.5 mg QD arm warrants further validation. Clinical trial information: NCT01867710. [Table: see text]

The efficacy of abiraterone acetate in treating Taiwanese chemo-refractory metastatic castration-resistant prostate cancer patients

ObjectiveTo evaluate the efficacy of abiraterone acetate in combination with prednisolone in Taiwanese men with metastatic castrate-resistant prostate cancer (mCRPC) who failed docetaxel-based chemotherapy. Materials and methodsIn this single-arm, open label study, 30 mCRPC patients with prostate specific antigen (PSA) progression after docetaxel chemotherapy were enrolled. All patients were treated with abiraterone acetate 1000 mg once daily and prednisolone 5 mg twice daily. The primary end-point was PSA response rate (defined as proportion of patients achieving a PSA decline of ≥50%). Secondary end-points were overall survival and time-to-PSA progression. ResultsAmong 28 patients who received one or more cycles of treatment, 15 (53.6%) men achieved PSA response [95% confidence interval (CI) 33.9–72.5]. The median time-to-PSA progression was 5.5 months (95% CI 3.1–7.9). The median interval from stopping abiraterone to death was 3.4 months (95% CI 0.1–21.0), and the median overall survival was 19.2 months (95% CI 13.0–25.4). The PSA responders had better overall survival compared with PSA nonresponders, in both univariate (log rank test, p = 0.007) and multivariate (Cox regression, p = 0.001; relative risk: 0.31; 95% CI: 0.12–0.76) analysis. Both a high Gleason score (≥8) and viscera involvement did not have an unfavorable response to abiraterone treatment. ConclusionA combination of abiraterone acetate and prednisolone can improve the overall survival in Taiwanese mCRPC patients who fail prior docetaxel chemotherapy.

Weekly low-dose docetaxel is an effective treatment with fewer adverse events for metastatic castration-resistant prostate cancer in Taiwanese patients

ObjectiveBased on the TAX 327 Phase III trial, docetaxel (DTX)-based chemotherapy is the standard first-line treatment for metastatic castration-resistant prostate cancer (mCRPC). However, some heterogeneity is observed in clinical practice. The present study aimed to evaluate the outcomes of a weekly low-dose DTX regimen, which is clinical practice at our institution, and to compare it with the standard triweekly DTX use in the TAX 327 trial. Materials and methodsWe reviewed the charts of all mCRPC patients treated with DTX 30 mg/m2 weekly on Days 1 and 8 of a 3-week cycle and prednisolone 5 mg twice daily between January 2006 and February 2014 in our hospital. ResultsIn the first-line setting, 19 patients with mCRPC received weekly DTX chemotherapy. The median four cycles of treatment were given in our cohort. The median follow-up period from the start of chemotherapy was 27.9 months (range 5.4–67.2months). The prostate-specific antigen (PSA) response rate was 47.3%, and the median overall survival was 15.8 months (range 1.2–34.5 months). The main toxicities were anemia (57%), fatigue (26%), and neuropathy (10%). Two patients had different Grade 3 to 4 adverse events (neutropenia and anemia). Our results revealed initial PSA <100 ng/mL, long duration (>12 months) of response to primary hormone therapy, rechallenge, and a higher accumulation dose of DTX were associated with good prognosis. ConclusionFor Taiwanese mCRPC patients, weekly DTX 30 mg/m2 is an efficient regimen for disease control with relatively low Grade 3 or 4 hematological adverse effects. The proper treatment duration of DTX therapy for mCRPC in Taiwanese patients is still uncertain, so further research is needed.

The influence of prior novel androgen receptor targeted therapy on the efficacy of cabazitaxel in men with metastatic castration-resistant prostate cancer

IntroductionThe treatment armamentarium for metastatic castration-resistant prostate cancer (mCRPC) has expanded with the introduction of several new therapies. In this treatment continuum, it is unclear whether the efficacy of cabazitaxel is affected by prior novel androgen receptor targeted therapies (ART) such as abiraterone and enzalutamide. In this study, we investigated the influence of prior ART on the efficacy of cabazitaxel in men with mCRPC. Patients and methodsData from an ongoing multicentre, phase II trial were used comprising 114 men with mCRPC treated with cabazitaxel in the post-docetaxel setting. The primary endpoints of the current analysis were prostate-specific antigen (PSA) response (⩾50%), and overall survival (OS). Univariate and multivariable analyses were conducted to investigate the influence of prior ART on the efficacy of cabazitaxel. ResultsFrom the 114 patients included in this analysis, 44 men received prior ART and 70 men did not receive prior ART before treatment with cabazitaxel. PSA response rates while on cabazitaxel treatment were similar in patients with and without prior ART (34% versus 40%, respectively, P=0.53). Likewise, median OS was not significantly different between men with and without prior ART (13.0 versus 14.0months, respectively, logrank P=0.65). In multivariable analysis, the only variables significantly associated with OS were performance status, serum albumin and alkaline phosphatase. ConclusionOur study showed that prior treatment with ART may not influence the efficacy of cabazitaxel in men with mCRPC. With emerging evidence of cross-resistance in the treatment of mCRPC, cabazitaxel provides a good treatment option irrespective of prior ART.

Safety and Clinical Outcomes of Abiraterone Acetate After Docetaxel in Octogenarians With Metastatic Castration-Resistant Prostate Cancer: Results of the Italian Compassionate Use Named Patient Programme

BackgroundProstate cancer mainly affects elderly men, who are often frail and whose reduced physiological reserves and multiple comorbidities increase the risk of side effects. The availability of new drugs has improved the overall survival (OS) of patients with castration-resistant prostate cancer (CRPC) but has increased the number of very elderly CRPC patients receiving anticancer drugs, raising questions about their efficacy and safety in this population. Patients and MethodsWe assessed the tolerability of abiraterone (AA) in a cohort of very elderly adults with metastatic CRPC (mCRPC) enrolled in the Italian AA named patient program and analyzed their clinical outcomes. We retrospectively reviewed the clinical records of 47 mCRPC patients aged > 80 years who had received AA after docetaxel. The Kaplan-Meier method was used to calculate OS and progression-free survival (PFS). Safety and clinical outcomes were also analyzed by age group (< 80 and > 80 years). Cox regression analysis was used to calculate the differences in PFS and OS between the groups according to the stratification variables. ResultsIn very elderly men, the prostate-specific antigen response rate was 48.9%, and the median PFS and OS were 8 and 18 months, respectively. The differences in toxicities between the older and younger age groups were not major. The limitation of the present study was mainly its retrospective nature. ConclusionOur data show that AA is active and safe in very elderly patients and leads to outcomes similar to those observed in younger patients, thus confirming that AA is a manageable therapeutic option for this patient population.

Efficacy of Cabazitaxel in Castration-resistant Prostate Cancer Is Independent of the Presence of AR-V7 in Circulating Tumor Cells

BackgroundAndrogen receptor splice variant 7 (AR-V7) in circulating tumor cells (CTCs) from patients with metastatic castration-resistant prostate cancer (mCRPC) was recently demonstrated to be associated with resistance to abiraterone and enzalutamide. Cabazitaxel might, however, remain effective in AR-V7-positive patients. ObjectiveTo investigate the association between AR-V7 expression in CTCs and resistance to cabazitaxel. Design, setting, and participantsWe selected patients with mCRPC from the multicenter, randomized, phase 2, randomized, open-label, multicenter study in mCRPC on the pharmacodynamic effects of budesonide on cabazitaxel (Jevtana) (CABARESC). Before the start of the first and third cabazitaxel cycle, CTCs were enumerated using the CellSearch System. In patients with ≥10 CTCs in 7.5ml blood at baseline, the expression of AR-V7 was assessed by quantitative polymerase chain reaction. Outcome measures and statistical analysisThe primary end point was the association between the AR-V7 status and the CTC response rate (decrease to fewer than five CTCs in 7.5ml blood during treatment). Secondary end points were the prostate-specific antigen (PSA) response rate (RR) and overall survival (OS). Analyses were performed using chi-square and log-rank tests. Results and limitationsAR-V7 was detected in 16 of 29 patients (55%) with ≥10 CTCs and was more frequently found in abiraterone pretreated patients (5 of 5 [100%] treated vs 7 of 20 [35%] untreated; p=0.009). We found no differences in CTC and PSA RRs. The presence of AR-V7 in CTCs was not associated with progression-free survival (hazard ratio [HR]: 0.8; 95% confidence interval [CI], 0.4–1.8) or overall survival (HR 1.6; 95% CI, 0.6–4.4). ConclusionsThe response to cabazitaxel seems to be independent of the AR-V7 status of CTCs from mCRPC patients. Consequently, cabazitaxel might be a valid treatment option for patients with AR-V7-positive CTCs. Patient summaryTools are needed to select specific treatments for specific patients at specific times. The presence of the gene AR-V7 in CTCs has been associated with resistance to anti-androgen receptor treatments. We investigated whether this holds true for cabazitaxel, but we found cabazitaxel to be effective independent of the presence of AR-V7.

Efficacy of low dose ketoconazole therapy for Chinese patients with castration resistant prostate cancer

To assess the efficacy of low dose ketoconazole therapy for Chinese patients with castration resistant prostate cancer (CRPC) and explore possible prognosis factors. From August 2006 to August 2011, 71 patients with CRPC were analyzed retrospectively, who received oral ketoconazole 200 mg, three times a day with prednisone 5 mg, twice a day. Prostate specific antigen (PSA) response rate was defined as the percentage of patients with PSA decline ≥ 50% compared to baseline PSA level during low dose ketoconazole therapy. Multivariate Logistic regression analysis and receiver operating characteristic curve were used to assess the prognostic factors and their accuracy. The mean initial serum PSA level was (205 ± 38) ng/ml for these patients with mean age (69 ± 1) years old. After first androgen deprivation therapy failure, the prostate cancer progressed into castration resistant stage. The baseline PSA was (93 ± 24) ng/ml and the baseline serum testosterone was (0.13 ± 0.02) ng/ml. During the low dose ketoconazole therapy, 31 patients (43.7%) had PSA decrease and 22 cases (31.0%) were effective with PSA decline more than 50%. PSA doubling time and baseline serum testosterone were positive correlation with PSA response rate by multivariate Logistic regression analysis. Patients with PSA doubling time of ≥ 3.0 months had a PSA response rate of 64.3% and the PSA response rate in those with < 3.0 months decreased to 22.8%, hazard rate (HR) = 0.149 (95% confidence interval [CI] 0.029 - 0.766), P = 0.023, area under the curve (AUC) = 0.707. The PSA response rate for patients with baseline serum testosterone ≥ 0.1 and < 0.1 µg/L were 55.6% and 5.7%, respectively, HR = 0.068 (95%CI 0.012 - 0.380), P = 0.002, AUC = 0.749. The common adverse reactions included liver dysfunction (17.9%), renal dysfunction (16.4%), fatigue (11.9%), nausea (6.0%) and anorexia (4.5%) and so on. Low dose ketoconazole therapy was a moderate, low toxicity hormonal therapy option for patients with CRPC. PSA doubling time ≥ 3 months and baseline serum testosterone ≥ 0.1 µg/L were predictors of desired effect for low dose ketoconazole therapy.

Baseline neutrophil–lymphocyte ratio (NLR) is associated with survival and response to treatment with second-line chemotherapy for advanced prostate cancer independent of baseline steroid use

The neutrophil-lymphocyte ratio (NLR), proposed as an indicator of cancer-related inflammation, has known prognostic value in prostate cancer. We examine its association with survival (OS) and response in patients treated with second-line chemotherapy. We analysed patients with metastatic castration-resistant prostate cancer (mCRPC) treated in the TROPIC trial, evaluating cabazitaxel versus mitoxantrone. Cox regression models were used to investigate the association of baseline NLR (BLNLR) with OS and the significance of a change in NLR count with treatment. Logistic regression models were used to determine the association of BLNLR counts with prostate specific antigen (PSA) and RECIST responses. The optimal NLR cut-off was established based on the concordance index of different values. Data from 755, 654 and 405 patients was available for OS, PSA and RECIST response analysis respectively. Median OS was 14.0 months [95% confidence interval (CI) 13.2-14.8]. Median NLR was 2.9 (IQR: 1.9-5.1). BLNLR was associated with survival (HR 1.5, 95% CI 1.1-2.1, P = 0.011) in multivariable analysis (MVA) independently of variables included in the Halabi nomogram, treatment arm and corticosteroid use. The optimal cut-off for a dichotomous NLR was selected at 3.0 based on its higher c-index related to survival. BLNLR ≥3.0 was associated with lower PSA response (40.1% versus 59.9%; P < 0.001) and RECIST response (7.7% versus 15.6%, P = 0.022) in MVA. Conversion from high (≥3) to low (<3) NLR was associated with improved survival (HR 0.66; 95% CI 0.51-0.85; P = 0.001) and higher PSA response rates (66.4% versus 33.6%; P = 0.000). Use of corticosteroids at baseline did not modify the association between NLR and survival. NLR is a valid prognostic biomarker in CRPC and is associated with survival, PSA and RECIST responses in patients treated with second-line chemotherapy. Changes in NLR counts with treatment may indicate benefit. NLR prognostic value is independent of prior use of corticosteroids. NCT00417079.

PII-LBA4 TERRAIN TRIAL: PROSTATE-SPECIFIC ANTIGEN KINETICS AND QUALITY OF LIFE RESULTS OF ENZALUTAMIDE VERSUS BICALUTAMIDE IN METASTATIC CASTRATION-RESISTANT PROSTATE CANCER

PII-LBA4 TERRAIN TRIAL: PROSTATE-SPECIFIC ANTIGEN KINETICS AND QUALITY OF LIFE RESULTS OF ENZALUTAMIDE VERSUS BICALUTAMIDE IN METASTATIC CASTRATION-RESISTANT PROSTATE CANCER

Everolimus plus bicalutamide for castration resistant prostate cancer (CRPC): Bench to bedside and back.

189 Background: We previously reported that the mammalian target of rapamycin (mTOR) pathway was upregulated in CRPC, and that simultaneous blockade of both androgen receptor (AR) and mTOR pathways synergized in killing CRPC cells. Methods: Eligible patients (pts) must have progressive CRPC with serum testosterone &lt;50 ng/dl. No prior bicalutamide (except to prevent flare) or everolimus was allowed. Treatment regimen included daily bicalutamide 50 mg and everolimus 10 mg orally. Primary endpoint was prostate specific antigen (PSA) response (defined as ≥30% reduction). Sample size of 23 pts would have the power of 0.8 and alpha error of 0.05 (one-sided) if the combination had a PSA response rate of 50% vs. a historical rate of 25% with bicalutamide alone. Molecular correlative studies including serum ERBB3 levels were performed by ELISA. LNCaP and C4-2 cells, modeling bicalutamide-sensitivity and resistance, respectively, were transfected with ErbB3 or an empty vector and subjected to western blotting. Results: Of 24 pts enrolled, the mean number of treatment cycles was 7.9 (1.0-23.0). Eighteen pts had a PSA response (75%, 95% CI: 0.53-0.90). Median overall survival was 28 months (95% CI 14.1-42.7). Fourteen pts (54%, 95% CI 0.37, 0.78) developed Grade 3 (13 pts) or Grade 4 (1 pt with sepsis) adverse events attributed to study treatment. Pts with partial response showed a greater decline in ErbB3 (P=0.037) compared to those with stable disease or disease progression. Consistent with these findings, everolimus induced a decline in ErbB3 in hormone-sensitive LNCaP cells but failed to affect ErbB3 in CRPC C4-2 cells, which expressed 8-fold higher levels of ErbB3. Increased expression of ErbB3 in LNCaP cells resulted in resistance to everolimus, whereas bicalutamide initially prevented this effect. Prolonged exposure to bicalutamide also resulted in an increase in ErbB3 which correlated with increased growth rates and cell invasion. Conclusions: The combination of bicalutamide and everolimus has very encouraging efficacy in men with bicalutamide-naïve CRPC, but with substantial everolimus-related toxicity. ERBB3 may contribute to resistance and deserves further study. Clinical trial information: NCT00814788.

Comparative analysis of the effectiveness of abiraterone before and after docetaxel in patients with metastatic castration-resistant prostate cancer.

To study the efficacy and safety of abiraterone in patients with and without prior chemotherapy. The databases including PubMed and abstracts presented at the American Society of Clinical Oncology meetings up to April 2014 were systematically searched. Eligible studies included randomized controlled trials (RCTs) in which abiraterone plus prednisone was compared to placebo plus prednisone in metastatic castration-resistant prostate cancer (CRPC) patients. The summary incidence, relative risk, hazard ratio and 95%CI were calculated using random or fixed-effects models. Heterogeneity test was performed to test between-study differences in efficacy and toxicity. A total of two phase III RCTs were included in our analysis, with metastatic CPRC patients before (n = 1088) and after chemotherapy (n = 1195). Prior chemotherapy did not significantly alter the effect of abiraterone on overall survival (P = 0.92) and prostate-specific antigen (PSA) progression-free survival (P = 0.13), but reduced its effect on radiographic-progression-free survival (P = 0.04), objective response rate (P < 0.001), and PSA response rate (P < 0.001). Prior chemotherapy significantly increased the specific risk of fluid retention and edema (P < 0.001) and hypokalemia (P < 0.001), but decreased the risk of all-grade hypertension (P < 0.001) attributable to abiraterone. There was no significant difference of cardiac disorders associated with abiraterone between the two settings (P = 0.58). Prior chemotherapy may reduce the effectiveness of abiraterone in patients with metastatic CRPC.

Metronomic oral cyclophosphamide plus prednisone in docetaxel-pretreated patients with metastatic castration-resistant prostate cancer.

We evaluated the efficacy and safety of metronomic oral cyclophosphamide (CTX) and prednisone in metastatic castration-resistant prostate cancer (mCRPC) patients. We analyzed retrospectively patients with mCRPC previously treated with docetaxel, and who received metronomic CTX (from 50mg PO daily to 150mg PO, 14days/7days off) and prednisone 10mg PO daily between September 2009 and April 2014 were analyzed. The primary endpoint was prostate-specific antigen (PSA) decrease ≥50%. Secondary analysis included PSA decrease ≥30%, time-to-treatment failure (TTF) and toxicity. Demographics and baseline characteristics were summarized using descriptive statistics. PSA response and adverse events were reported as relative rates. Kaplan-Meier estimates were calculated and plotted for time-to-event endpoints. Forty patients were evaluated. The median age was 69years old (52-86), 12 (30.0%) patients presented a Karnofsky performance status (KPS) of <80%, and 34 (85%) presented with bone with or without nodal metastases. Median pre-treatment PSA was 192ng/dL (7-2696ng/dL). All patients were previously exposed to docetaxel, including 33 (82.5%) with docetaxel-refractory disease. PSA response rate was achieved in eight (20.0%) out of 40 patients. Additionally, PSA declines of ≥30% occurred in 14 (35.0%) patients. The median TTF was 3months (95% confidence interval 2.5-3.5). The treatment was well tolerated. Grade 3/4 lymphopenia was reported in 11 (27.5%) patients and was the only grade 3-4 toxicity reported. Metronomic oral CTX showed activity and safety in docetaxel-pretreated mCRPC patients. This regimen deserves further investigation in this setting.

Biomodulatory Treatment of Patients with Castration-Resistant Prostate Cancer: A Phase II Study of Imatinib with Pioglitazone, Etoricoxib, Dexamethasone and Low-Dose Treosulfan.

Therapeutic options for patients with castration-resistant prostate cancer (CRPC) remain limited. In a multicenter, Phase II study, 65 patients with histologically confirmed CRPC received a biomodulatory regimen during the six-month core study. Treatment comprised daily doses of imatinib mesylate, pioglitazone, etoricoxib, treosulfan and dexamethasone. The primary endpoint was prostate-specific antigen (PSA) response. Responders could enter an extension phase until disease progression or intolerable toxicity occurred. Mean PSA was 45.3 ng/mL at baseline, and 77 % of patients had a PSA doubling time <3 months. Of the 61 evaluable patients, 37 patients (60.6 %) responded or had stable disease and 23 of them (37.7 % of 61 patients) were PSA responders. Among the 23 responders mean PSA decreased from 278.9 ± 784.1 ng/mL at baseline to 8.8 ± 11.6 ng/mL at the final visit (week 24). The progression-free survival (PFS) was 467 days in the ITT population. Of the 947 adverse events, 57.6 % were suspected to be drug-related, 13.8 % led to dose adjustment or permanent discontinuation and 40.2 % required concomitant medication. This novel combination approach led to an impressive PSA response rate of 37.7 % in CRPC patients. The good PSA response and PFS rate combined with the manageable toxicity profile suggest an alternative treatment option.

Efficacy and toxicity of anti-VEGF agents in patients with castration-resistant prostate cancer: a meta-analysis of prospective clinical studies.

Blocking angiogenesis by targeting vascular endothelial growth factor (VEGF) signaling pathway to inhibit tumor growth has proven to be successful in treating a variety of different metastatic tumor types, including kidney, colon, ovarian, and lung cancers, but its role in castration-resistant prostate cancer (CRPC) is still unknown. We here aimed to determine the efficacy and toxicities of anti-VEGF agents in patients with CRPC. The databases of PubMed, Web of Science and abstracts presented at the American Society of Clinical Oncology up to March 31, 2014 were searched for relevant articles. Pooled estimates of the objective response rate (ORR) and prostate-specific antigen (PSA) response rate (decline ≥50%) were calculated using the Comprehensive Meta-Analysis (version 2.2.064) software. Median weighted progression- free survival (PFS) and overall survival (OS) time for anti-VEGF monotherapy and anti-VEGF-based doublets were compared by two-sided Student's t test. A total of 3,841 patients from 19 prospective studies (4 randomized controlled trials and 15 prospective nonrandomized cohort studies) were included for analysis. The pooled ORR was 12.4% with a higher response rate of 26.4% (95%CI, 13.6-44.9%) for anti-VEGF-based combinations vs. 6.7% (95%CI, 3.5-12.7%) for anti-VEGF alone (p=0.004). Similarly, the pooled PSA response rate was 32.4% with a higher PSA response rate of 52.8% (95%CI: 40.2-65.1%) for anti-VEGF-based combinations vs. 7.3% (95%CI, 3.6-14.2%) for anti-VEGF alone (p<0.001). Median PFS and OS were 6.9 and 22.1 months with weighted median PFS of 5.6 vs. 6.9 months (p<0.001) and weighted median OS of 13.1 vs. 22.1 months (p<0.001) for anti-VEGF monotherapy vs. anti-VEGF-based doublets. With available evidence, this pooled analysis indicates that anti-VEGF monotherapy has a modest effect in patients with CRPC, and clinical benefits gained from anti-VEGF-based doublets appear greater than anti-VEGF monotherapy.

A Randomised Phase 2 Trial of Dexamethasone Versus Prednisolone in Castration-resistant Prostate Cancer

BackgroundPrednisolone is widely used as secondary hormonal treatment for castration-resistant prostate cancer (CRPC). We hypothesised that dexamethasone, another corticosteroid, is more active. ObjectiveTo compare the activity of prednisolone and dexamethasone in CRPC. Design, setting, and participantsThis single-centre, randomised, phase 2 trial was performed in 82 men with chemotherapy-naïve CRPC enrolled from 2006 to 2010. InterventionPrednisolone 5mg twice daily versus dexamethasone 0.5mg once daily versus intermittent dexamethasone 8mg twice daily on days 1–3 every 3 wk. Outcome measurements and statistical analysisThe main end point was prostate-specific antigen (PSA) response rate. Secondary end points included time to PSA progression, radiologic response rate using Response Evaluation Criteria In Solid Tumors (RECIST), and safety. Results and limitationsThe intermittent dexamethasone arm was dropped after no response was seen in seven patients. By intention to treat, confirmed PSA response was seen in 41% versus 22% for daily dexamethasone versus prednisolone, respectively (p=0.08). In evaluable patients, the PSA response rates were 47% versus 24% for dexamethasone and prednisolone, respectively (p=0.05). Median time to PSA progression was 9.7 mo on dexamethasone versus 5.1 mo on prednisolone (hazard ratio: 1.6; 95% confidence interval, 0.9–2.8). In 43 patients with measurable disease, the response rate by RECIST was 15% and 6% for dexamethasone and prednisolone, respectively (p=0.6). Of 23 patients who crossed over at PSA progression on prednisolone, 7 of the 19 evaluable (37%) had a confirmed PSA response to dexamethasone. Clinically significant toxicities were rare. ConclusionsDexamethasone may be more active than prednisolone in CRPC. In the absence of more definitive trials, dexamethasone should be used in preference to prednisolone. Patient summaryWe compared two different steroids used for treating men with advanced prostate cancer. Our results suggest that dexamethasone may be more effective than prednisolone and that both are well tolerated. Clinical trial registryEUDRAC 2005-006018-16

Abstract CT313: An exploratory analysis of efficacy and safety of abiraterone acetate (AA) in black patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) without prior chemotherapy (ctx)

Abstract Background Black pts are underrepresented in prostate cancer (PC) trials but have the highest incidence of and mortality rates from PC of any group. Aberrant activation of androgen receptor signaling in black pts may contribute to more aggressive PC. Abiraterone inhibits persistent androgen synthesis and prolongs survival in pts with mCRPC. We previously demonstrated that clinical outcomes and tolerability of AA are similar in black and non-black pts with mCRPC post-docetaxel. Herein, we explore the efficacy and safety of AA in black pts with mCRPC with no prior ctx. Methods COU-AA-302 (NCT00887198) is a randomized, double-blind phase 3 trial of AA (1000 mg + prednisone [P] 5 mg po BID) vs placebo + P in pts with mCRPC with no prior ctx. We evaluated prostate- specific antigen (PSA) response (≥ 50% and ≥ 90% decline from baseline), time to PSA progression (TTPP), and radiographic progression-free survival (rPFS) in black pts treated with AA + P vs placebo + P. Results 28/1088 (2.6%) pts were black and their median ages were 69 and 68 years for the AA and P groups, respectively. PSA response rate and median TTPP and rPFS were higher with AA vs P (Table). Clinical outcomesBlack pt populationOverall populationAA (n = 15)P (n = 13)AA (n = 546)P (n = 542)PSA response rate, n (%)≥ 50% decline8 (53.3)3 (23.1)336 (61.5)129 (23.8)≥ 90% decline8 (53.3)0 (0)168 (30.8)41 (7.6)TTPPMedian (95% CI)16.6 (3.75-NE)5.6 (1.87-16.49)11.1 (8.48-11.24)5.6 (5.39-5.59)HR (95% CI)0.428 (0.151-1.214)0.501 (0.432-0.581)rPFSMedian (95% CI)16.5 (5.49-NE)13.7 (3.71-NE)16.5 (13.77-16.76)8.3 (8.02-9.43)HR (95% CI)1.032 (0.312-3.412)0.525 (0.449-0.615)CI, confidence interval; NE, not estimable. Grade 3/4 treatment-emergent adverse events (TEAEs) occurring in 2 or more black pts were hypertension (4), dyspnea (2), anemia (2), syncope (2), and hypokalemia (2) in the AA group, and hypertension (2) in the P group. One pt in the AA group discontinued due to gastrointestinal hemorrhage. No TEAE-related deaths were reported. Conclusions Black pts experienced clinical benefit from AA with a safety profile similar to that of the overall study population, though low accrual of black pts limits our ability to draw formal conclusions. Additional studies of AA in black pts are under way to understand the benefit in this population (NCT01735396 and NCT01940276). Citation Format: Eleni Efstathiou, Hari Deshpande, Daniel George, Anthony M. Joshua, Mary-Ellen Taplin, Thomas W. Griffin, Anil Londhe, Mary Todd, Arturo Molina. An exploratory analysis of efficacy and safety of abiraterone acetate (AA) in black patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) without prior chemotherapy (ctx). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT313. doi:10.1158/1538-7445.AM2014-CT313

Docetaxel with or without zoledronic acid for castration-resistant prostate cancer.

The aim of this study was to evaluate the efficacy and safety of zoledronic acid (ZA) in the combination of docetaxel-based chemotherapy for castration-resistant prostate cancer with bone metastases. We conducted a prospective study in recruiting 105 prostate cancer patients with bone metastases from 2008 to 2010. Patients were randomly divided into two groups, 53 in the docetaxel-based chemotherapy + ZA(Group A) and 52 in the docetaxel-based chemotherapy + placebo(Group B). The different outcome between patients treated with chemotherapy combined with ZA and those with chemotherapy alone was evaluated. The Cox multivariate analyses of clinical features and different treatment methods of the 105 patients were conducted. There was a response of prostate-specific antigen (PSA) in 33 (62.3 %) in Group A and 28 (53.8 %) in Group B (P = 0.20). The combined approach group had better bone progression-free survival (BPFS) (9.0 vs. 6.0 months, P < 0.05) and overall survival (OS) (19.0 vs. 15.0 months, P = 0.02), but no statistical evidence of benefit was observed in terms of PSA response. Cox multivariate analysis identified the following independent prognostic factors: received ZA, high Hb level and more than 6 cycles of chemotherapy. There were no clinical relevant differences in the frequencies of adverse events between these two groups. Zoledronic acid treatment combined with docetaxel-based chemotherapy could have a better bone pain control and improve BPFS and OS for prostate cancer patients with bone metastases. The PSA response and SREs rate are similar.

AR-V7 and Resistance to Enzalutamide and Abiraterone in Prostate Cancer

BackgroundThe androgen-receptor isoform encoded by splice variant 7 lacks the ligand-binding domain, which is the target of enzalutamide and abiraterone, but remains constitutively active as a transcription factor. We hypothesized that detection of androgen-receptor splice variant 7 messenger RNA (AR-V7) in circulating tumor cells from men with advanced prostate cancer would be associated with resistance to enzalutamide and abiraterone.MethodsWe used a quantitative reverse-transcriptase–polymerase-chain-reaction assay to evaluate AR-V7 in circulating tumor cells from prospectively enrolled patients with metastatic castration-resistant prostate cancer who were initiating treatment with either enzalutamide or abiraterone. We examined associations between AR-V7 status (positive vs. negative) and prostate-specific antigen (PSA) response rates (the primary end point), freedom from PSA progression (PSA progression–free survival), clinical or radiographic progression–free survival, and overall survival.ResultsA total of 31 enzalutamide-treated patients and 31 abiraterone-treated patients were enrolled, of whom 39% and 19%, respectively, had detectable AR-V7 in circulating tumor cells. Among men receiving enzalutamide, AR-V7–positive patients had lower PSA response rates than AR-V7–negative patients (0% vs. 53%, P=0.004) and shorter PSA progression–free survival (median, 1.4 months vs. 6.0 months; P<0.001), clinical or radiographic progression–free survival (median, 2.1 months vs. 6.1 months; P<0.001), and overall survival (median, 5.5 months vs. not reached; P=0.002). Similarly, among men receiving abiraterone, AR-V7–positive patients had lower PSA response rates than AR-V7–negative patients (0% vs. 68%, P=0.004) and shorter PSA progression–free survival (median, 1.3 months vs. not reached; P<0.001), clinical or radiographic progression–free survival (median, 2.3 months vs. not reached; P<0.001), and overall survival (median, 10.6 months vs. not reached, P=0.006). The association between AR-V7 detection and therapeutic resistance was maintained after adjustment for expression of full-length androgen receptor messenger RNA.ConclusionsDetection of AR-V7 in circulating tumor cells from patients with castration-resistant prostate cancer may be associated with resistance to enzalutamide and abiraterone. These findings require large-scale prospective validation. (Funded by the Prostate Cancer Foundation and others.)