Cancer of the prostate is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that surrounds the urethra just below the bladder. Most prostate cancers are slow growing. Cancerous cells may spread to other areas of the body, particularly the bones and lymph nodes. It may initially cause no symptoms. In later stages, symptoms include pain or difficulty urinating, blood in the urine, or pain in the pelvis or back. Benign prostatic hyperplasia may produce similar symptoms. Other late symptoms include fatigue, due to low levels of red blood cells.
Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drugs that prevent androgens like testosterone and dihydrotestosterone (DHT) from mediating their biological effects in the body. They act by blocking the androgen receptor (AR) and/or inhibiting or suppressing androgen production. They can be thought of as the functional opposites of AR agonists, for instance androgens and anabolic steroids (AAS) like testosterone, DHT, and nandrolone and selective androgen receptor modulators (SARMs) like enobosarm. Antiandrogens are one of three types of sex hormone antagonists, the others being antiestrogens and antiprogestogens.
Bicalutamide, sold under the brand name Casodex among others, is an antiandrogen medication that is primarily used to treat prostate cancer. It is typically used together with a gonadotropin-releasing hormone (GnRH) analogue or surgical removal of the testicles to treat metastatic prostate cancer (mPC). To a lesser extent, it is used at high doses for locally advanced prostate cancer (LAPC) as a monotherapy without castration. Bicalutamide was also previously used as monotherapy to treat localized prostate cancer (LPC), but authorization for this use was withdrawn following unfavorable trial findings. Besides prostate cancer, bicalutamide is limitedly used in the treatment of excessive hair growth and scalp hair loss in women, as a puberty blocker and component of feminizing hormone therapy for transgender girls and women, to treat gonadotropin-independent early puberty in boys, and to prevent overly long-lasting erections in men. It is taken by mouth.
The androgen receptor (AR), also known as NR3C4, is a type of nuclear receptor that is activated by binding any of the androgenic hormones, including testosterone and dihydrotestosterone, in the cytoplasm and then translocating into the nucleus. The androgen receptor is most closely related to the progesterone receptor, and progestins in higher dosages can block the androgen receptor.
DU145 (DU-145) is a human prostate cancer cell line. DU145, PC3, and LNCaP are considered to be the standard prostate cancer cell lines used in therapeutic research.
Transmembrane protease, serine 2 is an enzyme that in humans is encoded by the TMPRSS2 gene. It belongs to the TMPRSS family of proteins, whose members are transmembrane proteins which have a serine protease activity. The TMPRSS2 protein is found in high concentration in the cell membranes of epithelial cells of the lung and of the prostate, but also in the heart, liver and gastrointestinal tract.
Melanoma-associated antigen 11 is a protein that in humans is encoded by the MAGEA11 gene. It is also involved in the androgen and progesterone receptor signaling pathways.
Enzalutamide, sold under the brand name Xtandi, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is indicated for use in conjunction with castration in the treatment of metastatic castration-resistant prostate cancer (mCRPC), nonmetastatic castration-resistant prostate cancer, and metastatic castration-sensitive prostate cancer (mCSPC). It is taken by mouth.
BMS-564,929 is an investigational selective androgen receptor modulator (SARM) which is being developed by Bristol-Myers Squibb for treatment of the symptoms of age-related decline in androgen levels in men ("andropause"). These symptoms may include depression, loss of muscle mass and strength, reduction in libido and osteoporosis. Treatment with exogenous testosterone is effective in counteracting these symptoms but is associated with a range of side effects, the most serious of which is enlargement of the prostate gland, which can lead to benign prostatic hypertrophy and even prostate cancer. This means there is a clinical need for selective androgen receptor modulators, which produce anabolic effects in some tissues such as muscle and bone, but without stimulating androgen receptors in the prostate.
The first antiandrogen was discovered in the 1960s. Antiandrogens antagonise the androgen receptor (AR) and thereby block the biological effects of testosterone and dihydrotestosterone (DHT). Antiandrogens are important for men with hormonally responsive diseases like prostate cancer, benign prostatic hyperplasia (BHP), acne, seborrhea, hirsutism and androgen alopecia. Antiandrogens are mainly used for the treatment of prostate diseases. Research from 2010 suggests that ARs could be linked to the disease progression of triple-negative breast cancer and salivary duct carcinoma and that antiandrogens can potentially be used to treat it.
EPI-001 is the first inhibitor of the androgen receptor amino-terminal domain. The single stereoisomer of EPI-001, EPI-002, is a first-in-class drug that the USAN council assigned a new stem class "-aniten" and the generic name "ralaniten". This distinguishes the anitens novel molecular mechanism from anti androgens that bind the C-terminus ligand-binding domain and have the stem class "lutamide". EPI-001 and its stereoisomers and analogues were discovered by Marianne Sadar and Raymond Andersen, who co-founded the pharmaceutical company ESSA Pharma Inc for the clinical development of anitens for the treatment of castration-resistant prostate cancer (CRPC).
Oxendolone, sold under the brand names Prostetin and Roxenone, is an antiandrogen and progestin medication which is used in Japan in the treatment of enlarged prostate. However, this use is controversial due to concerns about its clinical efficacy. Oxendolone is not effective by mouth and must be given by injection into muscle.
A nonsteroidal antiandrogen (NSAA) is an antiandrogen with a nonsteroidal chemical structure. They are typically selective and full or silent antagonists of the androgen receptor (AR) and act by directly blocking the effects of androgens like testosterone and dihydrotestosterone (DHT). NSAAs are used in the treatment of androgen-dependent conditions in men and women. They are the converse of steroidal antiandrogens (SAAs), which are antiandrogens that are steroids and are structurally related to testosterone.
Seviteronel is an experimental cancer medication which is under development by Viamet Pharmaceuticals and Innocrin Pharmaceuticals for the treatment of prostate cancer and breast cancer. It is a nonsteroidal CYP17A1 inhibitor and works by inhibiting the production of androgens and estrogens in the body. As of July 2017, seviteronel is in phase II clinical trials for both prostate cancer and breast cancer. In January 2016, it was designated fast-track status by the United States Food and Drug Administration for prostate cancer. In April 2017, seviteronel received fast-track designation for breast cancer as well.
Darolutamide, sold under the brand name Nubeqa, is an antiandrogen medication which is used in the treatment of non-metastatic castration-resistant prostate cancer in men. It is specifically approved to treat non-metastatic castration-resistant prostate cancer (nmCRPC) in conjunction with surgical or medical castration. The medication is taken by mouth twice per day with food.
Apalutamide, sold under the brand name Erleada among others, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is specifically indicated for use in conjunction with castration in the treatment of non-metastatic castration-resistant prostate cancer (NM-CRPC). It is taken by mouth.
Ralaniten acetate is a first-in-class antiandrogen that targets the N-terminal domain (NTD) of the androgen receptor (AR) developed by ESSA Pharmaceuticals and was under investigation for the treatment of prostate cancer. This mechanism of action is believed to allow the drug to block signaling from the AR and its splice variants. EPI-506 is a derivative of bisphenol A and a prodrug of ralaniten (EPI-002), one of the four stereoisomers of EPI-001, and was developed as a successor of EPI-001. The drug reached phase I/II prior to the discontinuation of its development. It showed signs of efficacy in the form of prostatic specific antigen (PSA) decreases (4–29%) predominantly at higher doses (≥1,280 mg) in some patients but also caused side effects and was discontinued by its developer in favor of next-generation AR NTD inhibitors with improved potency and tolerability.
BMS-641988 is a nonsteroidal antiandrogen which was developed by Bristol-Myers Squibb for the treatment of prostate cancer but was never marketed. It acts as a potent competitive antagonist of the androgen receptor (AR) (Ki = 10 nM; IC50 = 56 nM). The drug was found to have 20-fold higher affinity for the AR than bicalutamide in MDA-MB-453 cells, and showed 3- to 7-fold the antiandrogenic activity of bicalutamide in vitro. It may have some weak partial agonist activity at the androgen receptor. BMS-641988 is transformed by CYP3A4 into BMS-570511, and this metabolite is then reduced to BMS-501949 by cytosolic reductases. All three compounds show similar antiandrogenic activity. In addition to its antiandrogenic activity, BMS-641988 shows activity as a negative allosteric modulator of the GABAA receptor, and can produce seizures in animals at sufficiently high doses. It also shows some drug-induced QT prolongation. BMS-641988 reached phase I clinical trials prior to the discontinuation of its development. The clinical development of BMS-641988 was terminated due to the occurrence of a seizure in a patient during a phase I study.
EPI-7386 is an N-terminal domain antiandrogen, or antagonist of the N-terminal domain (NTD) of the androgen receptor (AR), which is under development for the treatment of prostate cancer. The compound was developed as a successor of previous drugs in the EPI series such as EPI-001, ralaniten (EPI-002), and ralaniten acetate (EPI-506). EPI-7386 shows 20-fold higher antiandrogenic potency than ralaniten in vitro (IC50 = 535 nM vs. 9,580 nM, respectively), as well as greater stability in human hepatocytes. It is planned to enter phase I clinical trials in 2020.
