What Is Enobosarm?
Enobosarm is an investigational oral medication classified as a Selective Androgen Receptor Modulator (SARM). As a new chemical entity, it is designed to act in a tissue-selective manner, meaning it targets specific tissues in the body. Clinical descriptions indicate that enobosarm has demonstrated dose-dependent improvements in body composition, specifically by increasing muscle mass and reducing fat mass. It has also shown potential to improve insulin resistance.
This SARM is being studied for its ability to enhance muscle strength. Importantly, trials have noted that enobosarm has not shown masculinizing effects in women, has neutral effects on the prostate in men, and does not increase hematocrit. Enobosarm is currently under investigation for a range of conditions, including metastatic breast cancer, metabolic issues like obesity and insulin resistance, and conditions associated with muscle loss and mobility disability.
Uses and Conditions Under Study
Enobosarm is currently being investigated in 6 clinical trials, involving a total of 452 participants. These studies explore its potential benefits across different disease areas. Sponsors for these trials include Veru Inc., City of Hope Medical Center, and Havah Therapeutics Pty Ltd.
A primary area of investigation is various forms of breast cancer. Enobosarm is being studied in 2 trials for metastatic breast cancer. Other breast cancer-related conditions under investigation include estrogen receptor negative, HER2/Neu negative, and metastatic triple-negative breast carcinoma. As a Selective Androgen Receptor Modulator (SARM), enobosarm may offer a targeted approach to managing these cancers, potentially by influencing hormone pathways or by preserving muscle mass during treatment.
Another significant focus is on metabolic health and body composition. Enobosarm is being studied for conditions such as obesity and overweight, and for its impact on HOMA-IR, which is an indicator of insulin resistance. Its demonstrated ability to increase muscle mass and reduce fat mass suggests it could be beneficial in managing these metabolic challenges. Mammographic density, a factor associated with breast cancer risk, is also being explored, potentially due to enobosarm's effects on body composition and hormonal balance.
Finally, enobosarm is under investigation for conditions related to muscle health and mobility. These include muscle loss and mobility disability. By increasing muscle mass and strength, enobosarm aims to improve physical function and quality of life for individuals experiencing these challenges.
Dosing
Enobosarm is primarily studied as an oral medication, meaning it is taken by mouth. Various investigational strengths and combination therapies have been explored in clinical trials.
Specific daily oral doses of enobosarm that have been studied include 3 mg, 6 mg, and 9 mg. For instance, one trial investigated oral enobosarm administered at a dose of 9 mg per day. When taken, it is typically administered once daily (QD).
Enobosarm has also been studied as part of combination therapies with other medications:
- In combination with subcutaneous injectable semaglutide, oral enobosarm was administered at either 3 mg or 6 mg daily.
- As part of a combination regimen with abemaciclib.
- As an oral combination therapy with anastrozole.
- Within a treatment plan that included pembrolizumab.
The precise dosage and regimen for enobosarm are determined by the specific condition under investigation and whether it is used alone or alongside other therapeutic agents.
Side Effects
Side effect data for Enobosarm was not provided in the available clinical trial information.
Clinical Trial Results
Androgen Receptor Positive Metastatic Triple Negative Breast Cancer
A Phase 2 clinical trial (NCT02971761) investigated the effectiveness of a combination therapy involving pembrolizumab and Enobosarm in 21 participants diagnosed with androgen receptor-positive metastatic triple-negative breast cancer. This specific type of breast cancer is aggressive and often challenging to treat, making new therapeutic approaches important. The trial aimed to assess how well patients responded to the treatment and how long they lived without their disease worsening or overall.
- Clinical Benefit Rate: Approximately 19% of patients (4 out of 21 participants) experienced a clinical benefit from the combination therapy. Clinical benefit is a broad measure that includes patients who achieved a complete response (disappearance of all cancer), a partial response (a significant reduction in tumor size), or stable disease (the cancer did not grow or shrink significantly) that lasted for at least 6 months. This outcome suggests that a notable portion of patients saw their disease either shrink or stabilize for a meaningful duration.
- Overall Survival: The median overall survival observed in this study was 25.5 months. Median overall survival represents the point at which half of the patients in the study were still alive. This metric provides an important indication of the treatment's impact on patient longevity in the context of metastatic disease.
- Progression-free Survival: Patients in the trial had a median progression-free survival of 2.6 months. Progression-free survival measures the time from the start of treatment until the disease progresses (gets worse) or the patient dies, whichever comes first. A longer progression-free survival indicates that the treatment is effective in controlling the cancer's growth for a longer period.
These findings from this early-phase study suggest that the combination of pembrolizumab and Enobosarm may offer a potential therapeutic option for patients with androgen receptor-positive metastatic triple-negative breast cancer, a population with limited treatment choices. Further research would typically be needed to confirm these results in larger patient groups and to understand the full clinical implications of these outcomes.