(S)-bicalutamide and Prostatic-Neoplasms

We designed and synthesized a series of 3-aryl-3-hydroxy-1-phenylpyrrolidine derivatives D and evaluated their potential as novel androgen receptor (AR) antagonists therapeutically effective against castration-resistant prostate cancer (CRPC). Introduction of a methyl group at the 2-position (R(2)) of the pyrrolidine ring increased the AR binding affinity. The (2S,3R) configuration of the pyrrolidine ring was favorable for the AR antagonistic activity. It was found that introduction of an amide substituent (R(1)) and a pyridin-3-yl group (Q) was effective for reducing the AR agonistic activity which appeared during the optimization of lead compound 6. Compound 54 showed potent antitumor effects against a CRPC model of LNCaP-hr cell line in a mouse xenograft, in which bicalutamide exhibited only partial suppression of tumor growth. Thus, the pyrrolidine derivatives such as 54 are novel AR antagonists, and their properties having efficacy against CRPC are distinct from those of a representative first-generation antagonist, bicalutamide.

Topics: Androgen Receptor Antagonists; Animals; Antineoplastic Agents; Castration; Cell Line, Tumor; Drug Design; Humans; Male; Mice; Models, Molecular; Prostate; Prostatic Neoplasms; Pyrrolidines; Receptors, Androgen; Xenograft Model Antitumor Assays

Androgen receptors (AR) are overexpressed in most primary and metastatic prostate cancers. To develop a nonsteroidal AR-mediated imaging agent, we synthesized and radiolabeled several analogs of the potent antiandrogen bicalutamide: [18F]bicalutamide, 4-[76Br]bromobicalutamide, and [76Br]bromo-thiobicalutamide. Two of these analogs, 4-[76Br]bromobicalutamide and [76Br]bromo-thiobicalutamide, were found to have a substantially increased affinity for the androgen receptor (AR) compared to that of bicalutamide. The synthesis of [18F]bicalutamide utilized a pseudocarrier approach to effect addition of a carbanion generated from tracer-level amounts of a radiolabeled precursor to an unlabeled carbonyl precursor. 4-[76Br]Bromobicalutamide and [76Br]bromo-thiobicalutamide were labeled through electrophilic bromination of a tributylstannane precursor. The former could be prepared in high specific activity, and its tissue distribution was tested in vivo. Androgen target tissue uptake was evident in castrated adult male rats; however, in DES-treated, AR-positive, tumor-bearing male mice, tumor uptake was low.

Topics: Androgen Antagonists; Anilides; Animals; Bromine Radioisotopes; Fluorine Radioisotopes; Isotope Labeling; Ligands; Male; Mice; Neoplasm Transplantation; Nitriles; Prostatic Neoplasms; Radioligand Assay; Radionuclide Imaging; Radiopharmaceuticals; Rats; Rats, Sprague-Dawley; Receptors, Androgen; Stereoisomerism; Structure-Activity Relationship; Tissue Distribution; Tosyl Compounds