Can an 86‑year‑old woman who has been receiving denosumab (Prolia) for over 10 years switch to the biosimilar denosumab (Jubbonti) because it is cheaper?

Switching from Prolia to Jubbonti: Yes, This is Safe and Appropriate

Yes, your 86-year-old patient can safely switch from Prolia to Jubbonti (denosumab biosimilar) to reduce costs. Jubbonti is FDA-approved as biosimilar to Prolia, meaning it has been demonstrated to be highly similar with no clinically meaningful differences in efficacy, safety, or immunogenicity 1.

Key Evidence Supporting the Switch

Regulatory Approval and Biosimilarity

Jubbonti received FDA approval in 2024 as a biosimilar to Prolia for all the same indications, including treatment of postmenopausal osteoporosis at high risk for fracture 1. The FDA designation confirms that biosimilarity has been established through rigorous comparative studies demonstrating equivalent clinical performance.

Clinical Evidence of Equivalence

Recent meta-analyses and randomized controlled trials demonstrate that denosumab biosimilars show:

• Equivalent lumbar spine bone mineral density (BMD) gains compared to reference denosumab (mean difference 0.02%; 95% CI -0.30 to 0.34; P = 0.92) 2
• Comparable bone turnover marker suppression (CTX and P1NP reductions >70%) 3
• Similar safety profiles with no new safety signals or neutralizing antibodies 3
• Equivalent immunogenicity with comparable anti-drug antibody formation 4

Real-World Patient Satisfaction

A large Canadian survey of 435 patients who switched from Prolia to Jubbonti found:

• 83.1% expressed satisfaction with the switch 5
• 84.8% were satisfied with the explanation provided about the biosimilar 5
• 72.7% valued the improved affordability 5
• Clear communication from healthcare providers was significantly associated with switch satisfaction (p < 0.001) 5

Critical Considerations for This Patient

After 10+ Years on Prolia

Your patient has been on denosumab for over 10 years, which is at the upper limit of available long-term data. The Endocrine Society guidelines note that data support denosumab use up to 10 years, with fracture reduction remaining stable throughout this period 6. After 5-10 years, fracture risk should be reassessed 6.

Important: If she remains at high fracture risk, continuing denosumab therapy (whether Prolia or Jubbonti) is appropriate. The switch to the biosimilar does not change the underlying treatment strategy.

Critical Warning About Treatment Continuity

Denosumab must never be stopped or delayed without transitioning to another antiresorptive therapy 6. This applies equally to both Prolia and Jubbonti. The guidelines emphasize this as an "Ungraded Good Practice Statement" because:

• Bone turnover rebounds rapidly (within 3-6 months) after discontinuation 6
• BMD returns to pretreatment levels within 18-24 months 6
• Multiple vertebral fractures can occur as early as 7 months after the last dose 1
• Doses should be given every 6 months without delay 6

Switching Does Not Equal Stopping

The switch from Prolia to Jubbonti is not a treatment discontinuation—it is simply changing to an equivalent medication. The 6-month dosing schedule must be maintained without interruption 1.

Practical Implementation

How to Execute the Switch

1. Timing: Administer Jubbonti at the next scheduled 6-month dose (when the next Prolia dose would be due)
2. No overlap needed: Do not give both medications
3. No gap allowed: Do not delay the scheduled dose timing
4. Continue supplementation: Ensure she continues calcium 1000 mg daily and vitamin D at least 400 IU daily 1

Patient Communication Points

Based on the real-world satisfaction data, explain to your patient:

• Jubbonti contains the same active ingredient (denosumab) as Prolia
• It works identically to prevent fractures
• Clinical studies confirm equivalent bone density improvements
• The cost savings can be substantial (biosimilars typically cost 25-75% less than reference products)
• The 6-month injection schedule remains unchanged
• She should report any concerns, but no different side effects are expected

Monitoring Considerations

For patients with advanced chronic kidney disease (eGFR <30 mL/min/1.73 m²), the FDA label for Jubbonti emphasizes evaluating for chronic kidney disease-mineral bone disorder (CKD-MBD) before each dose and monitoring calcium levels within 14 days of injection 1. If your patient has normal renal function, standard monitoring applies.

Common Pitfalls to Avoid

1. Do not create a treatment gap: The switch should occur seamlessly at the next scheduled dose
2. Do not give both medications: This is not combination therapy
3. Do not stop denosumab without a transition plan: If she ever needs to discontinue denosumab (either formulation), she must be transitioned to a bisphosphonate or other antiresorptive 6, 1
4. Do not assume interchangeability means automatic substitution: While biosimilars are highly similar, the prescriber should make the decision to switch and inform the patient 7

Cost-Effectiveness Context

Economic analyses demonstrate that biosimilar denosumab is cost-effective compared to bisphosphonates at willingness-to-pay thresholds of $100,000-$150,000 per quality-adjusted life-year, particularly in high-risk patients 8, 9. With sufficient price reductions (typically 25-75% below reference product), biosimilar denosumab becomes a dominant strategy (more effective and less costly) across varying fracture risk levels 8.

Bottom line: The switch to Jubbonti is medically appropriate, clinically equivalent, and financially advantageous for your patient. Proceed with the switch at her next scheduled dose, maintain the 6-month dosing interval, and ensure clear communication about the rationale and equivalence of the biosimilar.