Andrea Zivi

Abiraterone and Increased Survival in Metastatic Prostate Cancer

BACKGROUND Biosynthesis of extragonadal androgen may contribute to the progression of castration-resistant prostate cancer. We evaluated whether abiraterone acetate, an inhibitor of androgen biosynthesis, prolongs overall survival among patients with metastatic castration-resistant prostate cancer who have received chemotherapy. METHODS We randomly assigned, in a 2:1 ratio, 1195 patients who had previously received docetaxel to receive 5 mg of prednisone twice daily with either 1000 mg of abiraterone acetate (797 patients) or placebo (398 patients). The primary end point was overall survival. The secondary end points included time to prostate-specific antigen (PSA) progression (elevation in the PSA level according to prespecified criteria), progression-free survival according to radiologic findings based on prespecified criteria, and the PSA response rate. RESULTS After a median follow-up of 12.8 months, overall survival was longer in the abiraterone acetate-prednisone group than in the placebo-prednisone group (14.8 months vs. 10.9 months; hazard ratio, 0.65; 95% confidence interval, 0.54 to 0.77; P<0.001). Data were unblinded at the interim analysis, since these results exceeded the preplanned criteria for study termination. All secondary end points, including time to PSA progression (10.2 vs. 6.6 months; P<0.001), progression-free survival (5.6 months vs. 3.6 months; P<0.001), and PSA response rate (29% vs. 6%, P<0.001), favored the treatment group. Mineralocorticoid-related adverse events, including fluid retention, hypertension, and hypokalemia, were more frequently reported in the abiraterone acetate-prednisone group than in the placebo-prednisone group. CONCLUSIONS The inhibition of androgen biosynthesis by abiraterone acetate prolonged overall survival among patients with metastatic castration-resistant prostate cancer who previously received chemotherapy. (Funded by Cougar Biotechnology; COU-AA-301 ClinicalTrials.gov number, NCT00638690.).

Antitumour activity of docetaxel following treatment with the CYP17A1 inhibitor abiraterone: clinical evidence for cross-resistance?

BACKGROUND Abiraterone and docetaxel are both approved treatments for men with metastatic castration-resistant prostate cancer (mCRPC). Abiraterone pre-docetaxel is currently undergoing evaluation in a phase III study. In vitro studies indicate that taxanes may act by disrupting androgen receptor signalling. We hypothesised that prior abiraterone exposure would adversely impact docetaxel efficacy. PATIENTS AND METHODS We retrospectively evaluated activity of docetaxel in mCRPC patients previously treated with abiraterone, using Prostate Cancer Working Group and radiological criteria. RESULTS Of the 54 patients treated with abiraterone, 35 subsequently received docetaxel. Docetaxel resulted in a prostate-specific antigen (PSA) decline of ≥50% in nine patients [26%, 95% confidence interval (CI) 13% to 43%], with a median time to PSA progression of 4.6 months (95% CI 4.2% to 5.9%). PSA declines ≥30% were achieved by 13 patients (37%, 95% CI 22% to 55%). The median overall survival was 12.5 months (95% CI 10.6-19.4). All patients who failed to achieve a PSA fall on abiraterone and were deemed abiraterone-refractory were also docetaxel-refractory (N = 8). In the 24 patients with radiologically evaluable disease, partial responses were reported in four patients (11%), none of whom were abiraterone-refractory. CONCLUSION The activity of docetaxel post-abiraterone appears lower than anticipated and no responses to docetaxel were observed in abiraterone-refractory patients.BACKGROUND Abiraterone and docetaxel are both approved treatments for men with metastatic castration-resistant prostate cancer (mCRPC). Abiraterone pre-docetaxel is currently undergoing evaluation in a phase III study. In vitro studies indicate that taxanes may act by disrupting androgen receptor signalling. We hypothesised that prior abiraterone exposure would adversely impact docetaxel efficacy. PATIENTS AND METHODS We retrospectively evaluated activity of docetaxel in mCRPC patients previously treated with abiraterone, using Prostate Cancer Working Group and radiological criteria. RESULTS Of the 54 patients treated with abiraterone, 35 subsequently received docetaxel. Docetaxel resulted in a prostate-specific antigen (PSA) decline of ≥50% in nine patients [26%, 95% confidence interval (CI) 13% to 43%], with a median time to PSA progression of 4.6 months (95% CI 4.2% to 5.9%). PSA declines ≥30% were achieved by 13 patients (37%, 95% CI 22% to 55%). The median overall survival was 12.5 months (95% CI 10.6-19.4). All patients who failed to achieve a PSA fall on abiraterone and were deemed abiraterone-refractory were also docetaxel-refractory (N = 8). In the 24 patients with radiologically evaluable disease, partial responses were reported in four patients (11%), none of whom were abiraterone-refractory. CONCLUSION The activity of docetaxel post-abiraterone appears lower than anticipated and no responses to docetaxel were observed in abiraterone-refractory patients.

Antitumour activity of enzalutamide (MDV3100) in patients with metastatic castration-resistant prostate cancer (CRPC) pre-treated with docetaxel and abiraterone.

BACKGROUND The new generation anti-androgen enzalutamide and the potent CYP17 inhibitor abiraterone have both demonstrated survival benefits in patients with metastatic castration-resistant prostate cancer (CRPC) progressing after docetaxel. Preliminary data on the antitumour activity of abiraterone after enzalutamide have suggested limited activity. The antitumour activity and safety of enzalutamide after abiraterone in metastatic CRPC patients is still unknown. PATIENTS AND METHODS We retrospectively identified patients treated with docetaxel and abiraterone prior to enzalutamide to investigate the activity and safety of enzalutamide in a more advanced setting. Prostate specific antigen (PSA), radiological and clinical assessments were analysed. RESULTS 39 patients with metastatic CRPC were identified for this analysis (median age 70years, range: 54-85years). Overall 16 patients (41%) had a confirmed PSA decline of at least 30%. Confirmed PSA declines of ⩾50% and ⩾90% were achieved in 5/39 (12.8%) and 1/39 (2.5%) respectively. Of the 15 patients who responded to abiraterone, two (13.3%) also had a confirmed ⩾50% PSA decline on subsequent enzalutamide. Among the 22 abiraterone-refractory patients, two (9%) achieved a confirmed ⩾50% PSA decline on enzalutamide. CONCLUSION Our preliminary case series data suggest limited activity of enzalutamide in the post-docetaxel and post-abiraterone patient population.

The changing therapeutic landscape of castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) has a poor prognosis and remains a significant therapeutic challenge. Before 2010, only docetaxel-based chemotherapy improved survival in patients with CRPC compared with mitoxantrone. Our improved understanding of the underlying biology of CRPC has heralded a new era in molecular anticancer drug development, with a myriad of novel anticancer drugs for CRPC entering the clinic. These include the novel taxane cabazitaxel, the vaccine sipuleucel-T, the CYP17 inhibitor abiraterone, the novel androgen-receptor antagonist MDV-3100 and the radioisotope alpharadin. With these developments, the management of patients with CRPC is changing. In this Review, we discuss these promising therapies along with other novel agents that are demonstrating early signs of activity in CRPC. We propose a treatment pathway for patients with CRPC and consider strategies to optimize the use of these agents, including the incorporation of predictive and intermediate end point biomarkers, such as circulating tumor cells.

Phase II escalation study of sorafenib in patients with metastatic renal cell carcinoma who have been previously treated with anti-angiogenic treatment.

Study Type – Therapy (individual cohort)

Response to abiraterone acetate in the postchemotherapy setting in patients with castration-resistant prostate cancer whose disease progresses early on docetaxel.

17 Background: Abiraterone acetate (AA) has recently been approved for men with metastatic castration-resistant prostate cancer (CRPC) following docetaxel chemotherapy. AA inhibits CYP17, reducing androgen production and thereby impacting androgen receptor (AR) signalling. Recent evidence suggests taxanes also impact AR signalling, raising concerns about potential cross-resistance. We have previously shown that docetaxel has no antitumor activity in AA refractory patients. We have now evaluated the antitumor activity of AA post-docetaxel to determine the activity of AA in docetaxel refractory patients. METHODS Forty four men with CRPC treated with docetaxel (75 mg/m2 every 21 days) followed by post-chemotherapy AA at the Royal Marsden Hospital were identified. Radiological response by RECIST, PSA response by PSAWG2 criteria and symptomatic benefit were evaluated. RESULTS An average of 9 cycles of docetaxel were given (range 3-17); 7 patients discontinued chemotherapy due to progression of disease and 10 for toxicity. Of 40 patients with PSA data available, 26 (65%) had a PSA decline of at least 50%. At commencement of AA, median age was 68 years. Bone, nodal and visceral metastases were present in 38 (86%), 23 (52%) and 6 (14%) of the cohort respectively. An average of 5 months of treatment were delivered and 23 patients continue on AA. Of the 44, 7 (16%) patients had a 50% or greater PSA decline on AA. None of the 7 patients who were docetaxel refractory had a subsequent PSA, radiological or clinical response to AA. Of the 6 patients who received less than 5 cycles of docetaxel due to toxicity, 2 had subsequent PSA response on AA. There was no relationship between length of time on LHRH agonist and PSA response to AA. CONCLUSIONS Our data suggest that patients who are refractory to docetaxel do not respond to AA. Overall, in conjunction with our other evidence that in AA-refractory patients docetaxel has no antitumor activity, these data provide further evidence for cross-resistance between these two agents.

Volume of Bone Metastasis Assessed with Whole-Body Diffusion-weighted Imaging Is Associated with Overall Survival in Metastatic Castration-resistant Prostate Cancer

Purpose To determine the correlation between the volume of bone metastasis as assessed with diffusion-weighted (DW) imaging and established prognostic factors in metastatic castration-resistant prostate cancer (mCRPC) and the association with overall survival (OS). Materials and Methods This retrospective study was approved by the institutional review board; informed consent was obtained from all patients. The authors analyzed whole-body DW images obtained between June 2010 and February 2013 in 53 patients with mCRPC at the time of starting a new line of anticancer therapy. Bone metastases were identified and delineated on whole-body DW images in 43 eligible patients. Total tumor diffusion volume (tDV) was correlated with the bone scan index (BSI) and other prognostic factors by using the Pearson correlation coefficient (r). Survival analysis was performed with Kaplan-Meier analysis and Cox regression. Results The median tDV was 503.1 mL (range, 5.6-2242 mL), and the median OS was 12.9 months (95% confidence interval [CI]: 8.7, 16.1 months). There was a significant correlation between tDV and established prognostic factors, including hemoglobin level (r = -0.521, P < .001), prostate-specific antigen level (r = 0.556, P < .001), lactate dehydrogenase level (r = 0.534, P < .001), alkaline phosphatase level (r = 0.572, P < .001), circulating tumor cell count (r = 0.613, P = .004), and BSI (r = 0.565, P = .001). A higher tDV also showed a significant association with poorer OS (hazard ratio, 1.74; 95% CI: 1.02, 2.96; P = .035). Conclusion Metastatic bone disease from mCRPC can be evaluated and quantified with whole-body DW imaging. Whole-body DW imaging-generated tDV showed correlation with established prognostic biomarkers and is associated with OS in mCRPC. (©) RSNA, 2016 Online supplemental material is available for this article.

First-in-Human Study of CH5132799, an Oral Class I PI3K Inhibitor, Studying Toxicity, Pharmacokinetics, and Pharmacodynamics, in Patients with Metastatic Cancer

Purpose: This phase I dose-escalation study investigated the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT), safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary clinical activity of CH5132799. Experimental Design: Patients with metastatic solid tumors were eligible for the study. CH5132799 was administered orally once daily or twice daily in 28-day cycles. Results: Thirty-eight patients with solid tumors received CH5132799 at 2 to 96 mg once daily or 48 to 72 mg twice daily. The MTD was 48 mg on the twice-daily schedule but was not reached on the once daily schedule. DLTs were grade 3 elevated liver function tests (LFT), grade 3 fatigue, grade 3 encephalopathy, grade 3 diarrhea, and grade 3 diarrhea with grade 3 stomatitis; all DLTs were reversible. Most drug-related adverse events were grade 1/2. Diarrhea (34%) and nausea (32%) were the most common events. Mean Cmax and AUC0-24 in steady state at MTD were 175 ng/mL and 1,550 ng·h/mL, respectively, consistent with efficacious exposure based on preclinical modeling. Reduction in SUVmax with [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) was observed in 5 of 7 patients at MTD. A patient with PIK3CA-mutated clear cell carcinoma of the ovary achieved a partial response by GCIG CA125 criteria and further, a heavily pretreated patient with triple-negative breast cancer had marked improvement in her cutaneous skin lesions lasting six cycles. Conclusion: CH5132799 is well tolerated at the MTD dose of 48 mg twice daily. At this dose, the drug had a favorable PK and PD profile and preliminary evidence of clinical activity. Clin Cancer Res; 20(23); 5908–17. ©2014 AACR.

Safety and tolerability of pazopanib in the treatment of renal cell carcinoma

Introduction: Renal cell carcinoma (RCC) is still a challenging disease. Over the last 6 years, the use of novel targeted therapies interfering with vascularization and inhibition of other downstream pathways has revolutionized the therapy of this disease, leading to an improvement of patient outcomes. In particular, dysregulation of the vascular endothelial growth factor (VEGF) pathway and VEGF protein overexpression have proved important, as they result in increased tumor angiogenesis and RCC growth and development. Areas covered: This review briefly discusses the mechanisms of action and clinical applications of pazopanib. It mainly outlines the safety and tolerability of pazopanib for locally advanced/metastatic RCC. Phase III pazopanib safety data are also indirectly compared with other standard, antiangiogenic receptor tyrosine kinase inhibitors currently used in the management of RCC. Expert opinion: Pazopanib is a new drug available in the oncology portfolio to treat patients with predominantly clear-cell RCC. The toxicity profile of pazopanib is comparable, but in some ways distinct, from other antiangiogenic drugs used in the treatment of RCC. Long-term data about late side effects of this treatment are awaited.

Changing therapeutic paradigms in castrate-resistant prostate cancer.

Prostate cancer is the most common cancer, and the second leading cause of death from cancer, in males in most Western countries. Advanced prostate cancer is initially sensitive to androgen deprivation therapy, but usually progresses to the castration-resistant state. There is now incontrovertible evidence that castration-resistant prostate cancer (CRPC) remains hormone driven, with intratumoral steroid synthesis fueling tumor growth. Several novel agents targeted androgen receptor signaling are currently being evaluated including abiraterone and MDV3100. Recent results of the phase III trial of abiraterone acetate in post-docetaxel patients has shown an overall survival benefit in advanced CRPC. This new treatment is likely to become a new standard of care for patients with metastatic CRPC.