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.)

OBJECTIVES

To determine the activity and tolerability of 100-mg once-daily (QD) dasatinib in patients with metastatic castration-resistance prostate cancer (CRPC). Dasatinib, an oral Src family kinase inhibitor, has demonstrated both preclinical and clinical activity with twice-daily dosing in patients with metastatic CRPC.

METHODS

Chemotherapy-naive men with metastatic CRPC and increasing prostate-specific antigen levels were treated with dasatinib 100 mg QD. The primary measurement was a composite lack of disease progression, according to the Prostate Cancer Working Group 2 criteria, determined every 12 weeks during the study. The other analyses included changes in the prostate-specific antigen level, bone lesions, soft tissue disease, and bone turnover markers (urine N-telopeptide and bone alkaline phosphatase).

RESULTS

The present trial was designed before the publication of the recent Prostate Cancer Working Group 2 criteria; however, the analyses are presented to conform to the updated guidelines. A total of 48 patients received dasatinib. A lack of disease progression was observed in 21 patients (44%) at week 12 and in 8 (17%) at week 24. Urine N-telopeptide was reduced by ≥40% from baseline in 22 (51%) of 43 patients, and bone alkaline phosphatase was decreased in 26 (59%) of 44 patients. Dasatinib was well-tolerated, with only 6 patients (13%) with drug-related grade 3–4 adverse events and 3 (6%) with grade 3 adverse events. The most common treatment-related adverse events (≥20%) were fatigue, nausea, diarrhea, headache, and anorexia.

CONCLUSIONS

Dasatinib 100 mg QD has a favorable safety profile and maintains a similar degree of activity as the previously reported twice-daily dosing schedules. These data support additional study of dasatinib 100 mg QD for metastatic CRPC.

Bone metastases have a devastating impact on quality of life and bone pain in patients with prostate cancer and decrease survival. Animal models are important tools in investigating the pathogenesis of the disease and in developing treatment strategies for bone metastases, but few animal models recapitulate spontaneous clinical bone metastatic spread. In the present study, IGR-CaP1, a new cell line derived from primary prostate cancer, was stably transduced with a luciferase-expressing viral vector to monitor tumor growth in mice using bioluminescence imaging. The IGR-CaP1 tumors grew when subcutaneously injected or when orthotopically implanted, reconstituted the prostate adenocarcinoma with glandular acini-like structures, and could disseminate to the liver and lung. Bone lesions were detected using bioluminescence imaging after direct intratibial or intracardiac injections. Anatomic bone structure assessed using high-resolution computed tomographic scans showed both lytic and osteoblastic lesions. Technetium Tc 99m methylene diphosphonate micro single-photon emission computed tomography confirmed the mixed nature of the lesions and the intensive bone remodeling. We also identified an expression signature for responsiveness of IGR-CaP1 cells to the bone microenvironment, namely expression of CXCR4, MMP-9, Runx2, osteopontin, osteoprotegerin, ADAMTS14, FGFBP2, and HBB. The IGR-CaP1 cell line is a unique model derived from a primary tumor, which can reconstitute human prostate adenocarcinoma in animals and generate experimental bone metastases, providing a novel means for understanding the mechanisms of bone metastasis progression and allowing preclinical testing of new therapies.

Summary

Background

Bone metastases are a major burden in men with advanced prostate cancer. We compared denosumab, a human monoclonal antibody against RANKL, with zoledronic acid for prevention of skeletal-related events in men with bone metastases from castration-resistant prostate cancer.

Methods

In this phase 3 study, men with castration-resistant prostate cancer and no previous exposure to intravenous bisphosphonate were enrolled from 342 centres in 39 countries. An interactive voice response system was used to assign patients (1:1 ratio), according to a computer-generated randomisation sequence, to receive 120 mg subcutaneous denosumab plus intravenous placebo, or 4 mg intravenous zoledronic acid plus subcutaneous placebo, every 4 weeks until the primary analysis cutoff date. Randomisation was stratified by previous skeletal-related event, prostate-specific antigen concentration, and chemotherapy for prostate cancer within 6 weeks before randomisation. Supplemental calcium and vitamin D were strongly recommended. Patients, study staff, and investigators were masked to treatment assignment. The primary endpoint was time to first on-study skeletal-related event (pathological fracture, radiation therapy, surgery to bone, or spinal cord compression), and was assessed for non-inferiority. The same outcome was further assessed for superiority as a secondary endpoint. Efficacy analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00321620, and has been completed.

Findings

1904 patients were randomised, of whom 950 assigned to denosumab and 951 assigned to receive zoledronic acid were eligible for the efficacy analysis. Median duration on study at primary analysis cutoff date was 12·2 months (IQR 5·9–18·5) for patients on denosumab and 11·2 months (IQR 5·6–17·4) for those on zoledronic acid. Median time to first on-study skeletal-related event was 20·7 months (95% CI 18·8–24·9) with denosumab compared with 17·1 months (15·0–19·4) with zoledronic acid (hazard ratio 0·82, 95% CI 0·71–0·95; p=0·0002 for non-inferiority; p=0·008 for superiority). Adverse events were recorded in 916 patients (97%) on denosumab and 918 patients (97%) on zoledronic acid, and serious adverse events were recorded in 594 patients (63%) on denosumab and 568 patients (60%) on zoledronic acid. More events of hypocalcaemia occurred in the denosumab group (121 [13%]) than in the zoledronic acid group (55 [6%]; p<0·0001). Osteonecrosis of the jaw occurred infrequently (22 [2%] vs 12 [1%]; p=0·09).

Interpretation

Denosumab was better than zoledronic acid for prevention of skeletal-related events, and potentially represents a novel treatment option in men with bone metastases from castration-resistant prostate cancer.

Funding

Amgen.

Background

Carcinomas of unknown primary site (CUP) are epithelial malignancies revealed by metastatic lesions in the absence of any detectable primary tumor. Although they often adopt an aggressive clinical pattern, their basic biology remains poorly understood. Laboratory research on their biology have been hampered so far by the absence of cell lines representative of CUPs.

Methods

We attempted xenografts of CUP clinical specimens in immunodeficient mice and subsequent in vitro culture of transplanted malignant cells. Whenever possible, malignant xenografted or cultured cells were characterized by microsatellite genotyping, immunohistology, electron microscopy, multifish chromosome analysis and search of TP 53 gene mutations.

Results

Successful xenografts were achieved in 2 cases out of 4. One of them (Capi1) was lost after 3 passages whereas the other one (Capi3) has been adapted to in vitro culture and is currently available to the scientific community with reliable identification based on microsatellite genotyping. Both Capi1 and Capi3 have histological characteristics of adenocarcinomas and display intense expression of EMA, CEA and cytokeratin 7. Multifish chromosome analysis demonstrated a translocation involving chromosomes 4 and 21 in both specimens. Distinct rare missense mutations of the TP53 gene were detected in Capi1 (codon 312) and Capi3 (codon 181); the codon 181 mutation is consistent with a previously reported similar finding in a small series of CUP specimens. Finally, intense membrane expression of c-kit was recorded in Capi3.

Conclusion

Our data suggest that xenografted tumors can be obtained from a substantial fraction of CUP clinical specimens. The hypothesis of a preferential association of CUPs with TP 53 mutations of codon 181 deserves further investigations. The Capi3 cell line will be a useful tool for assessment of novel c-kit inhibitors.