Carcinoma of the prostate is the most commonly diagnosed cancer in men. The current pharmacological treatment of choice for progressive androgen-dependent prostate cancer is the nonsteroidal antiandrogen, bicalutamide, either as monotherapy or with adjuvant castration or luteinizing hormone-releasing hormone superagonists to block the synthesis of endogenous testosterone. To date, no nonsteroidal or antagonist-bound androgen receptor (AR) structure is available. We solved the x-ray crystal structure of the mutant W741L AR ligand-binding domain bound to R -bicalutamide at 1.8-Å resolution. This mutation confers agonist activity to bicalutamide and is likely involved in bicalutamide withdrawal syndrome. The three-dimensional structure demonstrates that the B ring of R -bicalutamide in the W741L mutant is accommodated at the location of the indole ring of Trp-741 in the WT AR bound to dihydrotestosterone. Knowledge of the binding mechanism for R -bicalutamide will provide molecular rationale for the development of new antiandrogens and selective AR modulators.

Background Cachexia, also known as muscle wasting, is a complex metabolic condition characterized by loss of skeletal muscle and a decline in physical function. Muscle wasting is associated with can...

Despite promising preclinical studies with the cyclin-dependent kinase inhibitor flavopiridol in chronic lymphocytic leukemia (CLL) and other diseases, previous clinical trials with this agent have been disappointing. The discovery of differential protein binding of flavopiridol in human and bovine serum contributed to an effective pharmacokinetic-derived schedule of administration of this agent. On the basis of pharmacokinetic modeling using our in vitro results and data from a previous trial, we initiated a phase 1 study using a 30-minute loading dose followed by 4 hours of infusion administered weekly for 4 of 6 weeks in patients with refractory CLL. A group of 42 patients were enrolled on 3 cohorts (cohort 1, 30 mg/m² loading dose followed by 30 mg/m² 4-hour infusion; cohort 2, 40 mg/m² loading dose followed by 40 mg/m² 4-hour infusion; and cohort 3, cohort 1 dose for treatments 1 to 4, then a 30 mg/m² loading dose followed by a 50 mg/m² 4-hour infusion). The dose-limiting toxicity using this novel schedule was hyperacute tumor lysis syndrome. Aggressive prophylaxis and exclusion of patients with leukocyte counts greater than 200 × 10⁹/L have made this drug safe to administer at the cohort 3 dose. Of the 42 patients treated, 19 (45%) achieved a partial response with a median response duration that exceeds 12 months. Responses were noted in patients with genetically high-risk disease, including 5 (42%) of 12 patients with del(17p13.1) and 13 (72%) of 18 patients with del(11q22.3). Flavopiridol administered using this novel schedule has significant clinical activity in refractory CLL. Patients with bulky disease and high-risk genetic features have achieved durable responses, thereby justifying further study of flavopiridol in CLL and other diseases.

Cancer cachexia is a complex metabolic condition characterized by loss of skeletal muscle. Common clinical manifestations include muscle wasting, anemia, reduced caloric intake, and altered immune function, which contribute to increased disability, fatigue, diminished quality of life, and reduced survival. The prevalence of cachexia and the impact of this disorder on the patient and family underscore the need for effective management strategies. Dietary supplementation and appetite stimulation alone are inadequate to reverse the underlying metabolic abnormalities of cancer cachexia and have limited long-term impact on patient quality of life and survival. Therapies that can increase muscle mass and physical performance may be a promising option; however, there are currently no drugs approved for the prevention or treatment of cancer cachexia. Several agents are in clinical development, including anabolic agents, such as selective androgen receptor modulators and drugs targeting inflammatory cytokines that promote skeletal muscle catabolism.