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.
Selective androgen receptor modulators (SARMs) are a class of drugs that selectively activate the androgen receptor in specific tissues, promoting muscle and bone growth while having less effect on male reproductive tissues like the prostate gland.
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.
Enobosarm, also formerly known as ostarine and by the developmental code names GTx-024, MK-2866, and S-22, is a selective androgen receptor modulator (SARM) which is under development for the treatment of androgen receptor-positive breast cancer in women and for improvement of body composition in people taking GLP-1 receptor agonists like semaglutide. It was also under development for a variety of other indications, including treatment of cachexia, Duchenne muscular dystrophy, muscle atrophy or sarcopenia, and stress urinary incontinence, but development for all other uses has been discontinued. Enobosarm was evaluated for the treatment of muscle wasting related to cancer in late-stage clinical trials, and the drug improved lean body mass in these trials, but it was not effective in improving muscle strength. As a result, enobosarm was not approved and development for this use was terminated. Enobosarm is taken by mouth.
Cabazitaxel, sold under the brand name Jevtana, is a semi-synthetic derivative of a natural taxoid. It is a microtubule inhibitor, and the fourth taxane to be approved as a cancer therapy.
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.
Galeterone is a steroidal antiandrogen which was under development by Tokai Pharmaceuticals for the treatment of prostate cancer. It possesses a unique triple mechanism of action, acting as an androgen receptor antagonist, androgen receptor down regulator, and CYP17A1 inhibitor, the latter of which prevents the biosynthesis of androgens. As a CYP17A1 inhibitor, galeterone shows selectivity for 17,20-lyase over 17α-hydroxylase.
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).
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 used for the treatment of prostate cancer. It is an androgen receptor inhibitor. It is taken by mouth.
Vosilasarm, also known by the development codes RAD140 and EP0062 and by the black-market name Testolone or Testalone, is a selective androgen receptor modulator (SARM) which is under development for the treatment of hormone-sensitive breast cancer. It is specifically under development for the treatment of androgen receptor-positive, estrogen receptor-negative, HER2-negative advanced breast cancer. Vosilasarm was also previously under development for the treatment of sarcopenia, osteoporosis, and weight loss due to cancer cachexia, but development for these indications was discontinued. The drug 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.
Craig M. Crews is an American scientist at Yale University known for his contributions to chemical biology. He is known for his contributions to the field of induced proximity through his work in creating heterobifunctional molecules that "hijack" cellular processes by inducing the interaction of two proteins inside a living cell. His initial work focused on the discovery of PROteolysis-TArgeting Chimeras (PROTACs) to trigger degradation of disease-causing proteins, a process known as targeted protein degradation (TPD), and he has since developed new versions of -TACs to leverage other cellular processes and protein families to treat disease.
A proteolysis targeting chimera (PROTAC) is a molecule that can remove specific unwanted proteins. Rather than acting as a conventional enzyme inhibitor, a PROTAC works by inducing selective intracellular proteolysis. A heterobifunctional molecule with two active domains and a linker, PROTACs consist of two covalently linked protein-binding molecules: one capable of engaging an E3 ubiquitin ligase, and another that binds to a target protein meant for degradation. Recruitment of the E3 ligase to the target protein results in ubiquitination and subsequent degradation of the target protein via the proteasome. Because PROTACs need only to bind their targets with high selectivity, there are currently many efforts to retool previously ineffective inhibitor molecules as PROTACs for next-generation drugs.
A (selective) androgen receptor degrader or downregulator (SARD) is a type of drug which interacts with the androgen receptor (AR) such that it causes the AR to be degraded and thus downregulated. They are under investigation for the treatment of prostate cancer and other androgen-dependent conditions.
Masofaniten, also known by its developmental code name 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). Masofaniten shows 20-fold higher antiandrogenic potency than ralaniten in vitro (IC50Tooltip Half-maximal inhibitory concentration = 535 nM vs. 9,580 nM, respectively), as well as greater stability in human hepatocytes. It was planned to enter phase I clinical trials in 2020. Preliminary results of a phase I/II clinical trial were published in 2023.
Chimeric small molecule therapeutics are a class of drugs designed with multiple active domains to operate outside of the typical protein inhibition model. While most small molecule drugs inhibit target proteins by binding their active site, chimerics form protein-protein ternary structures to induce degradation or, less frequently, other protein modifications.
Bavdegalutamide is an experimental proteolysis targeting chimera that functions as a androgen receptor degrader. It is being developed to treat metastatic castration-resistant prostate cancer.
Gridegalutamide is an investigational oral androgen receptor (AR) degrader being developed for the treatment of metastatic castration-resistant prostate cancer (mCRPC). It belongs to a class of drugs called proteolysis targeting chimeras (PROTACs), which are designed to selectively degrade specific proteins by hijacking the ubiquitin-proteasome system. CC-94676 employs a unique dual mechanism of action, combining AR degradation with AR antagonism, potentially offering advantages over traditional AR inhibitors in overcoming resistance mechanisms. Initially developed by Celgene and now under Bristol Myers Squibb, CC-94676 has demonstrated AR protein degradation and suppression of tumor growth in CRPC mouse models. As of 2024, CC-94676 is being evaluated in phase I clinical trials for patients with mCRPC who have progressed on androgen-deprivation therapy and at least one prior secondary hormonal therapy.
