Naohiro Fujimoto

Role of the Androgen-Androgen Receptor Axis in the Treatment Resistance of Advanced Prostate Cancer: From Androgen-Dependent to Castration Resistant and Further

After the introduction of prostate-specific antigen (PSA) screening, prostate cancer diagnosis has shifted to early and curative stages, although 10-20% of patients still present with metastatic and incurable cancer. Prostate cancer is androgen-dependent, and most patients with prostate cancer initially respond to androgen deprivation therapy (ADT). After 1-2 years of the treatment, advanced prostate cancer eventually progresses to castration resistant prostate cancer (CRPC). A variety of mechanisms of progression from androgen-dependent prostate cancer to CRPC under ADT have been postulated, and the key pathway is re-activation of the androgen-androgen receptor (AR) axis, for example, caused by AR mutation/overexpression/splice variants, altered expression of AR cofactors, and increased production of androgens. Recently approved new agents, such as the hormonal agents abiraterone and enzalutamide and the chemotherapeutic agent cabazitaxel, have demonstrated survival benefit in men with CRPC. However, the prolongation of survival times provided with these agents is limited because of the treatment resistance. Androgen-AR axis still plays a pivotal role in the resistance to the new agents for CRPC. To improve the prognosis of patients with CRPC, intensive research to identify effective agents, treatment strategies, and useful predictive biomarkers to select the patients who can benefit from such treatments are required. Additional clinical data, with a better understanding of the biology of CRPC, may provide better CRPC treatment outcomes. This article reviews the underlying mechanisms of treatment resistance and future direction of CRPC treatments.

Validation of the Kit for Detecting Mycoplasma Genitalium from the Male Urethritis

Mycoplasma genitalium is one of the pathogenic microorganisms in male urethritis as a sexually transmitted infection (STI). M.genitalium is detected in the urine specimens of 15-25% male patients with urethritis. The emergence of macrolide- or fluoroquinolone-resistant M.genitalium has become a serious problem in the treatment of male urethritis worldwide, but there is no commercial-based detecting kits accepted by the national insurance in Japan. In this study, we tested the validity of a molecular kit for detecting seven microorganisms related to STI (Anyplex™ II STI-7 Detection which detects Neisseria gonorrhoeae, Chlamydia trachomatis, M.genitalium, Mycoplasma hominis, Ureaplasma urealyticum, Ureaplasma parvum, Trichomonas vaginalis) produced by Seegene company in Korea. Seventeen M.genitalium strains were used to determine the detection limit of M.genitalium. M.genitalium DNA samples were extracted from M.genitalium strains and the diluted DNA samples were reacted to detect M.genitalium by the Anyplex™ II STI-7 Detection. The detection limit was determined as the maximum dilution of DNA samples and the number of M.genitalium DNA copies calculated. In this study, the minimum DNA copies to detect M.genitalium by the Anyplex™ II STI-7 Detection was determined to be around 50 per reaction. The detection rates of M.genitalium in urine specimens were compared between MgPa gene PCR and the Anyplex™ II STI-7 Detection. The positive and negative concordant rates were high as 96.4% (27/28) and 98.6% (71/72), respectively. The validity of the kit for detecting seven microorganisms related to STI (Anyplex™ II STI-7 Detection) was high and thought to be useful for clinical uses.

Chemosensitivity test by subrenal capsule assay (SRCA) in transitional cell carcinomas

From November, 1986 to October, 1989, the antitumor activities of several chemotherapeutic agents were tested by subrenal capsule assay (SRCA) in cases of 23 transitional cell carcinomas. Overall sensitivities of tested drugs to transitional cell carcinomas were compatible to clinical data and correlated with individual clinical courses. This method has some problems, but can be carried out at any institute and serve as an aid to the selection of chemotherapeutic agents.