Understanding Osteoporosis and the Need for New Treatments
Osteoporosis is a systemic skeletal disease that makes bones weak and more likely to break [1.5.2]. It affects millions globally, with postmenopausal women being at particularly high risk due to estrogen deficiency, which leads to increased bone resorption (breakdown) exceeding bone formation [1.5.2]. For years, the main treatments have been antiresorptive agents like bisphosphonates, which slow bone loss. However, the demand for more effective therapies, especially those that can actively build new bone (anabolic agents), has driven significant research and development. As we look at the pharmacological landscape in 2025, the focus is on both innovative new mechanisms and increasing accessibility to powerful existing treatments.
The Rise of Biosimilars in 2024-2025: Denosumab
A major development in 2024 and 2025 has been the approval and launch of multiple biosimilars for denosumab (the reference product is Prolia) [1.2.3, 1.3.4]. Denosumab is a monoclonal antibody that works by targeting RANKL, a protein essential for the formation and survival of osteoclasts, the cells responsible for bone resorption [1.2.3]. By inhibiting RANKL, it reduces bone breakdown and increases bone mass and strength [1.2.3].
The FDA has approved numerous denosumab biosimilars, significantly impacting the market:
- Jubbonti (denosumab-bbdz): Approved in March 2024 as the first interchangeable biosimilar for Prolia [1.2.2, 1.2.7]. It launched in the US in June 2025 [1.2.3].
- Stoboclo (denosumab-bmwo): Received FDA approval in March 2025 and became available in July 2025 [1.2.1, 1.2.4].
- Bildyos (denosumab-nxxp): Approved by the FDA in September 2025 [1.2.5].
- Bosaya (denosumab-kyqq): Also approved in September 2025, it is another biosimilar to Prolia [1.2.3].
These biosimilars are approved for the same indications as Prolia, including treating postmenopausal women with osteoporosis at high risk for fracture [1.2.2]. Their introduction is a critical step in expanding patient access and offering significant cost-saving potential [1.2.1].
Advanced Anabolic Agents: Romosozumab and Abaloparatide
While biosimilars increase access, truly novel mechanisms focus on building new bone. Two powerful anabolic agents are central to treating high-risk patients: romosozumab and abaloparatide.
Romosozumab (Evenity) Romosozumab is a monoclonal antibody that works by inhibiting sclerostin, a protein that stops bone formation [1.4.2, 1.5.1]. By blocking sclerostin, romosozumab has a dual effect: it powerfully stimulates new bone formation and, to a lesser extent, decreases bone resorption [1.5.1]. This makes it one of the most potent osteoanabolic agents available [1.5.3].
- Efficacy: In the FRAME clinical trial, one year of romosozumab reduced the risk of new vertebral fractures by 73% compared to a placebo [1.4.1].
- Administration: It is given as a monthly injection for 12 months. After the course is complete, treatment must be followed by an antiresorptive agent like denosumab to maintain the gains in bone density [1.4.2, 1.5.3].
- Safety: Romosozumab carries a boxed warning for a potential increased risk of heart attack, stroke, and cardiovascular death. It should not be used in patients who have had a myocardial infarction or stroke within the previous year [1.5.2, 1.5.3].
Abaloparatide (Tymlos) Abaloparatide is a synthetic peptide that, like teriparatide (Forteo), activates the parathyroid hormone (PTH) receptor, stimulating new bone formation [1.6.3]. However, it does so with a more selective action that may result in less stimulation of bone resorption compared to teriparatide [1.6.3]. In the ACTIVE clinical trial, abaloparatide reduced the risk of new vertebral fractures by 86% compared to placebo [1.6.3]. Real-world data from 2025 suggests that over 18 months, abaloparatide was associated with significantly lower rates of hip and nonvertebral fractures compared to teriparatide [1.6.1].
Comparison of Modern Osteoporosis Therapies
| Feature | Denosumab (Prolia) | Romosozumab (Evenity) | Abaloparatide (Tymlos) |
|---|---|---|---|
| Mechanism of Action | Antiresorptive: RANKL inhibitor, decreases bone resorption [1.2.3]. | Dual Effect: Sclerostin inhibitor, increases bone formation and decreases resorption [1.5.1]. | Anabolic: PTH receptor agonist, primarily stimulates new bone formation [1.6.3]. |
| Administration | Subcutaneous injection every 6 months [1.4.6]. | Two subcutaneous injections, once a month for 12 months [1.4.2]. | Daily subcutaneous injection, for up to 2 years [1.4.7]. |
| Vertebral Fracture Reduction | ~68% vs. placebo [1.4.7]. | ~73% vs. placebo (at 12 months) [1.4.1]. | ~86% vs. placebo [1.6.3]. |
| Key Consideration | Multiple biosimilars available in 2025 [1.2.3]. Bone loss can be rapid after stopping. | Treatment limited to 1 year, must be followed by an antiresorptive [1.4.2]. Boxed warning for cardiovascular risk [1.5.3]. | Can cause transient increases in calcium levels. |
The Future Pipeline: What's Next?
Beyond 2025, the osteoporosis drug pipeline continues to be active, with over 30 companies developing more than 35 potential therapies [1.3.2, 1.3.5]. Some notable candidates in development include:
- TST002 (Blosozumab): An anti-sclerostin monoclonal antibody, similar to romosozumab. It is currently in Phase II trials and has shown potential to stimulate bone formation and inhibit bone resorption [1.3.5].
- AGA2118: A bispecific antibody targeting both Sclerostin and DKK1, another inhibitor of bone formation. It is in Phase II trials for postmenopausal osteoporosis [1.3.3].
- Oral Formulations: Researchers are working on oral anabolic agents to provide a less burdensome alternative to daily injections. Rani Therapeutics' RT-102, an oral capsule containing a parathyroid hormone analog, showed promising results in a Phase 1 study [1.4.9].
Conclusion
To answer 'What is the new drug for osteoporosis 2025?', there isn't one single blockbuster approval. Instead, 2025 is characterized by a significant shift towards increased access and affordability through the launch of multiple denosumab biosimilars [1.2.1, 1.2.3]. For high-risk patients, potent anabolic agents like romosozumab and abaloparatide remain the cutting edge of therapy, offering significant fracture reduction by actively building new bone [1.4.1, 1.6.1]. The future looks promising, with pipeline drugs exploring novel pathways and more convenient oral formulations, continuing the evolution of osteoporosis management.
For more information from an authoritative source, you may visit: National Institute of Arthritis and Musculoskeletal and Skin Diseases
