LHRH agonist + antiandrogen

The combination of LHRH (Luteinizing Hormone-Releasing Hormone) agonists with antiandrogens represents an important therapeutic approach in prostate cancer management. This combination therapy, also known as combined androgen blockade (CAB), complete androgen blockade, maximal androgen blockade, or total androgen blockade, works through complementary mechanisms to achieve more comprehensive androgen suppression than either agent alone[3][5]. ## Mechanism of Action LHRH agonists work by initially stimulating the pituitary gland to produce luteinizing hormone, but with continued administration, they cause the pituitary to stop producing LH, resulting in decreased testosterone production from the testes (medical or chemical castration)[3]. However, LHRH agonists have a significant limitation - they cause an initial surge in testosterone levels (known as "testosterone flare" or "flare phenomenon") that can last 5-15 days at the beginning of treatment[2][3]. Antiandrogens complement this action by binding to androgen receptors in prostate cells, preventing any remaining androgens (including those from adrenal sources) from stimulating cancer growth[1][5]. When used together, the antiandrogen neutralizes the effects of the initial testosterone flare caused by LHRH agonists and blocks the action of adrenal androgens that aren't affected by LHRH agonist therapy[2][9]. ## Clinical Benefits The combination therapy offers several advantages: 1. Prevention of disease flare-up: Antiandrogens neutralize the effects of the transient increase in testosterone caused by LHRH agonists[2][10]. 2. More comprehensive androgen blockade: While LHRH agonists reduce testicular androgens, they don't affect adrenal androgen production. Antiandrogens block the action of these remaining androgens[5]. 3. Improved efficacy: Clinical studies show a trend toward greater efficacy with combined treatment compared to monotherapy[1]. 4. Rapid response: The combination can achieve a 60% decrease in serum prostatic acid phosphatase within 5 days of treatment initiation[2]. ## Available Agents **LHRH agonists** approved for prostate cancer treatment include: - Leuprolide (Lupron Depot, Eligard, Camcevi) - Goserelin (Zoladex) - Triptorelin (Trelstar)[3] **Antiandrogens** include: - Non-steroidal antiandrogens: flutamide, anandron (nilutamide), bicalutamide[1][4] - Newer generation antiandrogens: enzalutamide, apalutamide, darolutamide ## Side Effects The combination therapy can cause various side effects: 1. Hot flashes, decreased libido, erectile dysfunction, and fatigue shortly after starting treatment[7]. 2. Metabolic changes leading to weight gain, increased risk of diabetes, heart attack, and sudden death[7]. 3. Bone loss increasing fracture risk[7]. 4. Gastrointestinal side effects (more common with antiandrogens): abdominal pain, diarrhea, constipation, nausea/vomiting, and anorexia[10]. 5. Potential hepatotoxicity with some antiandrogens[10]. Despite these side effects, the combination of LHRH agonists with antiandrogens remains an important treatment option for prostate cancer, offering more comprehensive androgen suppression than either agent alone.

Other names

combined androgen blockadecomplete androgen blockademaximal androgen blockadetotal androgen blockade