Therapeutic options in docetaxel-refractory metastatic castration-resistant prostate cancer: a cost-effectiveness analysis.

BACKGROUND: Docetaxel is an established first-line therapy to treat metastatic castration-resistant prostate cancer (mCRPC). Recently, abiraterone and cabazitaxel were approved for use after docetaxel failure, with improved survival. National Institute for Health and Clinical Excellence (NICE) preliminary recommendations were negative for both abiraterone (now positive in final recommendation) and cabazitaxel (negative in final recommendation). OBJECTIVE: To evaluate the cost-effectiveness of abiraterone, cabazitaxel, mitoxantrone and prednisone for mCRPC treatment in US. METHODS: A decision-tree model was constructed to compare the two mCRPC treatments versus two placebos over 18 months from a societal perspective. Chance nodes include baseline pain as a severity indicator, grade III/IV side-effects, and survival at 18 months. Probabilities, survival and health utilities were from published studies. Model cost inputs included drug treatment, side-effect management and prevention, radiation for pain, and death associated costs in 2010 US dollars. RESULTS: Abiraterone is a cost-effective choice at $94K/QALY (quality adjusted life years) compared to placebo in our base-case analysis. Cabazitaxel and abiraterone are the most effective, yet also most expensive agents. The incremental cost-effectiveness ratios (ICER) at base-case are $101K/QALY (extended dominated) for mitoxantrone vs. placebo, $91K/QALY for abiraterone vs. mitoxantrone, $956K/QALY for cabazitaxel vs. abiraterone. Abiraterone becomes less cost-effective as its AWP increases, or if the cost of mitoxantrone side-effect management decreases. Increases in the percentage of patients with baseline pain leads to an increased ICER for both mitoxantrone and abiraterone, but mitoxantrone does relatively better. Cabazitaxel remains not cost-effective. CONCLUSION: Our base case model suggests that abiraterone is a cost-effective option in docetaxel-refractory mCRPC patients. Newer treatments will also need a CEA assessment compared to abiraterone.

Structure of the progesterone receptor-deoxyribonucleic acid complex: novel interactions required for binding to half-site response elements.

The DNA binding domain (DBD) of nuclear hormone receptors contains a highly conserved globular domain and a less conserved carboxyl-terminal extension (CTE). Despite previous observations that the CTEs of some classes of nuclear receptors are structured and interact with DNA outside of the hexanucleotide hormone response element (HRE), there has been no evidence for such a CTE among the steroid receptors. We have determined the structure of the progesterone receptor (PR)-DBD-CTE DNA complex at a resolution of 2.5 A, which revealed binding of the CTE to the minor groove flanking the HREs. Alanine substitutions of the interacting CTE residues reduced affinity for inverted repeat HREs separated by three nucleotides, and essentially abrogated binding to a single HRE. A highly compressed minor groove of the trinucleotide spacer and a novel dimerization interface were also observed. A PR binding site selection experiment revealed sequence preferences in the trinucleotide spacer and flanking DNA. These results, taken together, support the notion that sequences outside of the HREs influence the DNA binding affinity and specificity of steroid receptors.