Evenity (Romosozumab) FAERS Safety Signals: What Women Need to Know

What Is Romosozumab and Why Does It Matter for Women's Bone Health?

Romosozumab (brand name Evenity) works differently from every other osteoporosis drug on the market. It blocks sclerostin, a protein made by osteocytes that normally puts the brakes on new bone formation. By neutralizing sclerostin, the drug simultaneously increases bone formation and decreases bone resorption, a dual action no bisphosphonate or denosumab can match.

Osteoporosis is a disease that disproportionately affects women. Approximately one in two women over age 50 will have an osteoporosis-related fracture in her lifetime, compared with one in four men. The accelerated bone loss that begins in perimenopause and sharply intensifies in the first three to five years after the final menstrual period is driven by estrogen withdrawal. That estrogen-driven bone loss is the biological context in which romosozumab was developed and where its benefits are most relevant.

How Sclerostin Inhibition Differs From Other Mechanisms

Bisphosphonates (alendronate, risedronate, zoledronic acid) and denosumab work exclusively on the resorption side. Teriparatide and abaloparatide stimulate formation but can also increase resorption markers over time. Romosozumab's dual mechanism means lumbar spine bone mineral density (BMD) gains of 13.3% at 12 months in the FRAME trial are larger than what any single-mechanism drug achieves in the same timeframe.

Speed matters when a woman has already fractured. A patient with a recent vertebral fracture faces her second fracture risk within 12 months at rates as high as 20%, a phenomenon sometimes called the "imminent fracture" window. Romosozumab's rapid BMD gains and fracture reduction within that first year make it attractive precisely because time is the constraint.

Which Women Are Considered High Fracture Risk?

The FDA approval is specifically for postmenopausal women who:

• Have a history of osteoporotic fracture, or
• Have multiple risk factors for fracture, and
• Have failed or are intolerant to other available osteoporosis therapies

"High fracture risk" in clinical practice is usually defined by a FRAX 10-year major osteoporotic fracture probability of 20% or a hip fracture probability of 3%, though some guidelines use more nuanced thresholds based on BMD T-score and age.

The FDA Approval Story and Label Evolution

April 2019 Approval

The FDA approved romosozumab on April 9, 2019, based primarily on two phase 3 trials: FRAME (romosozumab versus placebo, followed by denosumab) and ARCH (romosozumab versus alendronate). The approval was not straightforward. An FDA advisory committee voted 18 to 1 in favor of approval but also voted 17 to 2 that the cardiovascular data needed explicit labeling.

The prescribing information released at approval carried a boxed warning, which is the FDA's strongest label warning, stating that romosozumab may increase the risk of myocardial infarction (MI), stroke, and cardiovascular death. Patients who have had an MI or stroke within the preceding year should not receive romosozumab.

What the Current Label Says

The current Evenity label requires that prescribers:

1. Ask about cardiovascular history before initiating treatment
2. Avoid use in patients who have experienced MI or stroke within 12 months
3. Discontinue if MI or stroke occurs during therapy
4. Supplement calcium and vitamin D during treatment

The label also states that the 12-month treatment course should not be extended, and that anti-resorptive therapy should follow romosozumab to maintain the BMD gains achieved.

FAERS Safety Signals: What the Spontaneous Report Database Shows

The FDA Adverse Event Reporting System (FAERS) is a pharmacovigilance database of voluntary and mandatory adverse event reports submitted by patients, healthcare providers, and manufacturers. FAERS data are hypothesis-generating, not confirmatory. Signal detection uses disproportionality analyses such as the reporting odds ratio (ROR) or information component (IC).

Cardiovascular Events: The Primary Signal

The cardiovascular signal for romosozumab emerged during the ARCH trial and was subsequently tracked in FAERS after approval. In ARCH, 2.5% of romosozumab-treated patients experienced a serious cardiovascular adverse event compared with 1.9% of alendronate-treated patients, a numerical imbalance that reached statistical significance in the pre-specified analysis. The absolute difference was 16 additional serious CV events per 1,000 patients treated for one year.

Post-market FAERS analysis of romosozumab through 2023 shows that cardiovascular system disorders, specifically acute MI and cerebrovascular accident, rank among the top five reported serious adverse event categories. Disproportionality signals have been detected for both MI (ROR approximately 2.1, 95% CI 1.4 to 3.1 in a published pharmacovigilance study) and stroke, consistent with the trial-identified signal. This is not a theoretical concern confined to clinical trial populations; real-world prescribing confirms it.

Hypersensitivity and Injection-Site Reactions

The second major FAERS signal cluster involves hypersensitivity. The label lists angioedema, erythema multiforme, urticaria, and dermatitis as reported reactions. Injection-site erythema, pain, and bruising appear in approximately 18% of patients in clinical trials. FAERS reports suggest a small subset of patients (well under 1% of estimated exposure) report systemic hypersensitivity requiring medical attention.

Hypocalcemia

Romosozumab increases bone formation rapidly, which requires calcium. Without adequate supplementation, hypocalcemia can develop, particularly in women with pre-existing vitamin D deficiency or renal impairment. The label mandates correction of hypocalcemia before initiating therapy. FAERS contains hypocalcemia reports, though the signal strength is lower than the cardiovascular cluster, likely because the risk is modifiable with supplementation.

Osteonecrosis of the Jaw and Atypical Femoral Fractures

These two rare adverse events are class effects of osteoporosis therapies that inhibit bone resorption. Because romosozumab also has anti-resorptive activity (in addition to its anabolic effect), the label includes warnings for both osteonecrosis of the jaw (ONJ) and atypical femoral fractures (AFF). FAERS contains a small number of reports for each. The absolute incidence of ONJ with romosozumab is estimated to be far lower than with long-term bisphosphonate or denosumab use, though head-to-head surveillance data are limited.

Sex-Specific Physiology: How Being a Woman Shapes Risk and Benefit

Postmenopausal Biology and the Cardiovascular Question

Here is the tension that makes romosozumab complicated for women specifically. Women in the postmenopausal age group treated in ARCH (mean age 74 years) already carry elevated baseline cardiovascular risk. The absolute excess cardiovascular risk in ARCH must be weighed against the absolute fracture reduction. In ARCH, romosozumab followed by alendronate reduced new vertebral fractures by 48% at 24 months and clinical fractures by 27% compared with alendronate alone.

For a 70-year-old postmenopausal woman with a prior vertebral fracture and low cardiovascular risk, the fracture benefit likely outweighs the cardiovascular risk. For a woman who had an MI eight months ago, the drug is contraindicated. The clinical calculus sits between those poles.

Does the Menstrual Cycle or Hormonal Status Change Pharmacokinetics?

Romosozumab is approved exclusively for postmenopausal women, so pharmacokinetic data in premenopausal or perimenopausal women are sparse. What is known is that sclerostin levels are inversely correlated with estrogen levels. Premenopausal women have lower sclerostin and higher endogenous bone formation than postmenopausal women, which may mean the drug's efficacy signal would be different in younger women, though this remains unstudied in trials.

There are no cycle-phase-specific dosing data. The once-monthly injection schedule is not calibrated to the menstrual cycle.

Perimenopausal Women: A Data Gap

Women in perimenopause experience an accelerating rate of bone loss even before the final menstrual period. Romosozumab has not been studied in this population. The FDA label does not include perimenopausal women, and off-label use in this group lacks safety or efficacy evidence. Women in perimenopause who are concerned about bone loss should discuss DEXA screening, dietary calcium optimization (1,000 mg per day), vitamin D (600 to 800 IU per day), and weight-bearing exercise as first steps.

Pregnancy, Lactation, and Contraception: Required Reading

Pregnancy: Absolutely Contraindicated

Romosozumab is contraindicated in pregnancy. This is not a gray-zone caution; it is a hard stop.

Animal studies (rats and rabbits) at doses comparable to human exposure showed fetal harm including increased fetal loss and skeletal abnormalities. Sclerostin plays a role in fetal skeletal development, so the mechanism for potential harm is biologically plausible.

There are no controlled human data. The drug has a long half-life of approximately 6.4 days, and because it is a monoclonal antibody (IgG2 subclass), it may cross the placenta, particularly in the second and third trimesters when active placental transport of IgG antibodies is highest.

Any woman of reproductive potential who is prescribed romosozumab must use effective contraception during treatment and for a sufficient wash-out period after the last dose. Given the 12-month treatment course and the antibody half-life, most experts recommend at least five half-lives (approximately 32 days) before any planned conception attempt, though this question should be discussed individually with the prescribing clinician.

Romosozumab is not indicated for premenopausal women, which means accidental pregnancy exposure would be rare. Any such exposure should be reported to the Amgen pregnancy pharmacovigilance registry (1-800-772-6436).

Lactation: No Data, Avoid

There are no human data on romosozumab transfer into breast milk. Given that the drug is a large IgG2 monoclonal antibody, gastrointestinal absorption by a breastfed infant would likely be minimal if any transfer occurred, but the absence of data means the drug should be avoided during breastfeeding. The indicated postmenopausal population makes lactation exposure uncommon, but the guidance should be explicit in any clinical conversation.

Contraception Requirements

Because the drug is indicated for postmenopausal women, most patients will not need contraception counseling for pregnancy prevention. However, any woman receiving romosozumab who is not yet confirmed postmenopausal (12 consecutive months of amenorrhea in the absence of other causes) should use effective contraception throughout the 12-month treatment course.

Who This Is Right for, and Who Should Not Take It

Good Candidates (Postmenopausal Life Stage)

A postmenopausal woman is likely a reasonable candidate for romosozumab if she:

• Is at very high or imminent fracture risk (recent vertebral fracture, T-score below minus 2.5 with additional risk factors)
• Has no history of MI or stroke in the prior 12 months and no clinically significant cardiovascular disease
• Has tried or cannot tolerate bisphosphonates and has not had adequate response
• Understands the 12-month-only duration and the requirement for sequential anti-resorptive therapy afterward
• Has had hypocalcemia corrected before starting

Women Who Should Not Take Romosozumab

Romosozumab is not appropriate for women who:

• Had an MI or stroke within the past 12 months (absolute contraindication per label)
• Are pregnant or trying to conceive
• Are premenopausal or perimenopausal (no evidence base)
• Have uncorrected hypocalcemia
• Have severe renal impairment (creatinine clearance <30 mL/min, where denosumab requires caution and pharmacokinetic data for romosozumab are limited)

Special Considerations by Life Stage

Postmenopause (primary population): The 12-month course followed by denosumab or a bisphosphonate is the evidence-based sequence. Women who discontinue romosozumab without starting an anti-resorptive risk rapid BMD loss.

Perimenopausal: No data. Do not use off-label.

Reproductive years: Contraindicated. Bone loss in this group from conditions like hypothalamic amenorrhea, hyperprolactinemia, or premature ovarian insufficiency requires different management (address the underlying cause, consider hormonal therapy).

Postpartum and lactation: Contraindicated.

Sequential Therapy: Why What Comes After Romosozumab Matters

Romosozumab is an anabolic agent, and anabolic bone gains are partly lost if anti-resorptive therapy does not follow immediately. The FRAME extension data showed that transitioning to denosumab after romosozumab maintained and extended BMD gains at both the lumbar spine and total hip. Transitioning to alendronate is also acceptable per published guidance, though the BMD gains are somewhat less durable.

Stopping romosozumab and starting nothing is a clinical mistake. The American Society for Bone and Mineral Research (ASBMR) task force and The Menopause Society both recommend sequential anti-resorptive therapy after any anabolic agent.

Women who complete romosozumab and then stop denosumab later face a further consideration: denosumab discontinuation causes a rapid rebound increase in bone resorption that can produce multiple vertebral fractures within 12 to 24 months. The sequencing of osteoporosis therapy requires a long-term plan, not a 12-month prescription.

What Patients and Clinicians Can Do With FAERS Data

FAERS reports are publicly searchable through the FDA FAERS Public Dashboard. Women and clinicians can search for romosozumab (or Evenity) to see reported adverse events, their frequency among reports, and how they compare with the drug's label.

A few important caveats about interpreting FAERS:

• Reports represent suspected, not confirmed, drug-caused events
• Under-reporting is substantial; estimates suggest only 1 to 10% of adverse events are ever reported
• Disproportionality signals in FAERS indicate that an event is reported more often than expected given overall reporting patterns, not that the drug caused the event
• The strongest evidence for a safety signal comes when FAERS data are consistent with randomized trial data, as is the case for romosozumab's cardiovascular signal

If you experience a potential adverse event while taking romosozumab, you or your clinician can submit a report directly through FDA MedWatch. Patient-submitted reports are accepted and carry the same regulatory weight as clinician-submitted reports.

Monitoring Recommendations During Treatment

Women taking romosozumab should have the following monitored:

• Serum calcium and vitamin D before initiation and periodically during treatment
• Blood pressure and cardiovascular symptom review at each monthly injection visit
• Dental examination before starting (to minimize ONJ risk; delay elective invasive dental procedures until after the 12-month course if possible)
• BMD by DEXA at baseline and 12 to 24 months after completing the course (not during, as the short-term BMD increase does not predict long-term fracture reduction in a time frame that changes management within the 12-month course)

Calcium supplementation of 500 to 1,000 mg per day (dietary plus supplement combined total of 1,200 mg) and vitamin D of 600 to 800 IU per day are required during treatment.

The Evidence Gap in Women: Where Data Are Thin

Women have historically been included in clinical trials less often than men, and even when included, sex-disaggregated pharmacokinetic and safety data are rarely the primary focus. For romosozumab, the clinical trial populations in FRAME and ARCH were entirely postmenopausal women, which means there is actually better sex-specific data here than for many drugs.

What is missing:

• Premenopausal and perimenopausal efficacy and safety data
• Data in women with PCOS (who may have altered sclerostin levels and different bone microarchitecture)
• Data in women with a history of breast cancer or on aromatase inhibitors (who have accelerated bone loss and elevated fracture risk, often in their 50s)
• Long-term cardiovascular outcome data beyond the 12-month treatment and 12-month follow-up in ARCH
• Pharmacokinetic data across body weight extremes (women with BMI <18 or BMI above 40)

Women with cancer-treatment-induced bone loss from aromatase inhibitors or GnRH agonists used for endometriosis represent a group with high fracture risk who have almost no data to guide romosozumab use. Their cardiovascular risk profiles may differ substantially from the postmenopausal women in the registration trials.

The ACOG Committee on Gynecologic Practice notes that management decisions in women treated for breast cancer with aromatase inhibitors should involve coordinated care between oncology and the prescribing bone specialist.