Evenity's dual-action mechanism
Evenity, with the active ingredient romosozumab, is a monoclonal antibody that targets and inhibits a protein called sclerostin. By blocking sclerostin, which naturally inhibits bone formation, Evenity has a dual effect: it increases new bone formation and decreases bone resorption (breakdown). This differs from antiresorptive medications like bisphosphonates, which only slow bone loss. This ability to build new bone contributes to its significant impact on bone mineral density (BMD).
Quantifying bone density increases from clinical trials
Clinical studies provide data on bone density increases during the 12-month Evenity treatment. Percentage changes vary by skeletal site and prior treatment.
Lumbar Spine (Lower Back)
Studies in postmenopausal women have shown significant increases in lumbar spine BMD, including a 16.9% mean increase in one study and a 13.7% increase compared to 5.0% with alendronate in another. A study in men aged 55–90 found an average 12% increase in lumbar spine BMD within one year.
Total Hip and Femoral Neck
In postmenopausal women, the ARCH study showed a 6.2% increase in total hip BMD and a 5.3% increase in femoral neck BMD at 12 months, which were greater than the increases seen with alendronate.
Factors influencing bone density gains
Factors can influence individual responses to Evenity.
Impact of Prior Treatment
Patients who have not previously used antiresorptive drugs generally experience more substantial and rapid BMD gains from Evenity. Prior use of antiresorptive agents can reduce the subsequent BMD response to Evenity, though it remains effective.
Other Predictive Factors
Baseline BMD T-score and body mass index (BMI) may also predict the magnitude of BMD change at certain sites.
Comparison of BMD increases: Evenity vs. other therapies
The table below compares 12-month BMD increases for Evenity and other common osteoporosis treatments, based on various studies.
| Skeletal Site | Evenity (12 months) | Alendronate (12 months) | Teriparatide (12 months) |
|---|---|---|---|
| Lumbar Spine | Up to 16.9% increase | ~5.0% increase | ~7.1% increase |
| Total Hip | Up to 6.2% increase | ~2.8% increase | Increases less than Evenity |
| Femoral Neck | Up to 5.3% increase | ~2.1% increase | Increases less than Evenity |
The importance of post-Evenity therapy
After the initial 12-month Evenity treatment, transitioning to a potent antiresorptive agent like alendronate or denosumab is crucial to maintain BMD gains and protect against fractures. This sequential approach has been shown to support continued BMD increases and maintained fracture risk reduction.
Important safety information
Evenity has a boxed warning due to an increased risk of stroke, heart attack, and cardiovascular death seen in one trial. It should not be initiated in patients who have had a heart attack or stroke in the preceding year. Less common risks include osteonecrosis of the jaw, unusual femur fractures, and low blood calcium. Calcium and vitamin D supplementation as directed by a doctor is advised.
Conclusion
Evenity is a powerful treatment for severe osteoporosis, rapidly increasing bone mineral density. Clinical trials demonstrate substantial BMD gains within 12 months, particularly in the lumbar spine, often exceeding those of other therapies due to its unique bone-building mechanism. Following Evenity with long-term antiresorptive therapy is essential to preserve the gains. Understanding these effects and assessing patient risks are key for optimal outcomes.
A useful resource for more information is the National Institutes of Health (NIH).
