Treatment Sequence With Romosozumab Influences Osteoporosis Outcomes

Neil Osterweil

November 10, 2020

Timing is everything when it comes to the use of the anabolic agent romosozumab (Evenity) for the treatment of advanced osteoporosis, a review of clinical trials suggests.

In four studies with treatment sequences in which romosozumab was administered either before or following the use of an antiresorptive agent, initial treatment with 1 year of romosozumab produced substantial bone mineral density (BMD) gains in the total hip and lumbar spine.

Transition from romosozumab to a potent resorptive agent, either alendronate or denosumab (Prolia) augmented the initial gains, reported Felicia Cosman, MD, professor of clinical medicine at Columbia University, New York.

Romosozumab was the third approved agent in its class, following teriparatide in 2002, and abaloparatide (Tymlos) in 2017, both of which have been shown to produce rapid reductions in fracture risk and large improvements in BMD when they were administered up front, followed by an antiresorptive agent.

"But since romosozumab has a very different mechanism of action compared to both teriparatide and abaloparatide, we didn't know if treatment sequence would be as important for this agent as it was for teriparatide," she said during a press briefing prior to her presentation of the data in an oral abstract session at the virtual annual meeting of the American College of Rheumatology.

Two for One

Romosozumab is unique in that it both increases bone formation and decreases bone resorption, and has been shown in treatment-naive postmenopausal women with osteoporosis to significantly improve BMD and reduce fracture risk, compared with either placebo or alendronate. Romosozumab has also been studied as sequential therapy in patients treated initially with either alendronate or denosumab.

To see whether treatment sequence could have differential effects on clinical outcomes for patients with osteoporosis, Cosman and colleagues looked at results from four clinical trials, using levels of bone turnover markers (procollagen type I N-terminal propeptide [PINP] and beta-isomer of the C-terminal telopeptide of type I collagen [beta-CTX]) and BMD gains in the total hip and spine as outcomes.

The two trials of romosozumab in treatment-naive women were the ARCH trial comparing romosozumab with alendronate in a double-blind phase for 1 year, followed by 1 year of open-label alendronate, and the FRAME trial, in which romosozumab was compared with placebo in a 1-year double-blind phase, followed by 1-year of open-label denosumab.

The two trials of romosozumab in women treated initially with antiresorptive agents were the STRUCTURE trial in which patients on oral bisphosphonates for at least 3 years or alendronate 70 mg weekly for 1 year were randomized to receive either romosozumab or teriparatide, and a phase 2 trial (NCT00896532) that included a 24-month romosozumab or placebo treatment phase followed by rerandomization to a 12-month extension phase with denosumab or placebo, followed by a 12-month retreatment phase with romosozumab, followed by a 24-month follow-on phase with zoledronic acid or no intervention.

Total Hip BMD Gains

In the ARCH trial, total hip BMD increased 6.2% with 1 year of romosozumab, and a cumulative total of 7.1% with the 2-year romosozumab/alendronate sequence. In the FRAME trial, patients gained 6.8% in total hip BMD after 1 year of romosozumab and a total of 8.8% after 2 years of romosozumab followed by denosumab.

In contrast, in the STRUCTURE trial, patients treated for 1 year or longer with alendronate and then with 1 year of romosozumab had a 2.9% BMD gain in the total hip. In the phase 2 trial, 1 year of romosozumab following 1 year of denosumab yielded a 0.9% BMD gain, for a total gain of 3.8% with the denosumab sequence.

Lumbar Spine BMD Gains

In ARCH, lumbar spine BMD increased 13.7% with 1 year of romosozumab, and a total of 15.2% with the 2-year sequence of romosozumab followed by alendronate. Similarly, in FRAME, patients gained 13.3% in BMD after a year of romosozumab, and total of 17.6% by the end of the 2-year romosozumab/denosumab sequence.

In contrast, in STRUCTURE, patients who had previously been on alendronate for at least 1 year had a gain of 9.8% after 1 year of romosozumab, and in the phase 2 study, patients who had been on denosumab for 1 year had an increase in lumbar spine BMD of 5.3% after 1 year on romosozumab, and a total gain of 11.5% at the end of the 2-year sequence.

Serum PINP and Beta-CTX

Looking at the markers of bone turnover, the investigators saw that, in both ARCH and FRAME, PINP peaked at over 80% of baseline at 1 month, and then continued to steadily decline past 1 year. The beta-CTX nadir was 40%-50% below baseline at 1 year.

At the end of year 2, the PINP nadir was –67% with follow-on alendronate, and –69% with denosumab, and the beta-CTX nadir was –72% and –92%, respectively.

In the two trials where romosozumab was the follow-on therapy, however, the trends were distinctly different. In STRUCTURE, for example, PINP peaked at 141% of baseline at 1 month, and then returned toward baseline, whereas beta-CTX remained largely unchanged.

In the phase 2 trial, PINP peaked at 28% above baseline at 9 months, and then only slightly declined, and beta-CTX peaked at 211% at the end of 1 year of romosozumab.

Best Used Up Front

"This study is important, because it suggests that for the three bone-building drugs that the best effects will really be attained on bone strength if the agents are used as initial therapy in very-high-risk patients. Those are people who have sustained fractures within the preceding 2 years, who had multiple fractures at any point in their adulthood, and who present with very low BMD, particularly if they have any associated clinical risk factors such as family history or other underlying diseases or medications that have detrimental effects on bone," Cosman said at the briefing.

Marcy Bolster, MD, from the division of rheumatology, allergy, and immunology at Massachusetts General Hospital, Boston, and associate professor of medicine at Harvard Medical School in Boston, who was not involved in the study, commented that the study provides important information for clinicians who treat patients with osteoporosis.

"We have an increasing number of medications available for use in the treatment of patients with osteoporosis, and as we consider the importance of reducing fracture risk, the duration of therapy, the timing of a bisphosphonate holiday, it is essential that we consider any advantages to the order or sequence of our medications," she said when asked for comment.

"This study provides evidence supporting the concept of the 'anabolic window' in which there is a demonstrated advantage in treating patients with an anabolic agent prior to treatment with an antiresorptive agent, and while gains in bone mineral density were achieved with either order of medication use, the gains were more dramatic with treatment with romosozumab as the first agent," she added.

Bolster also noted it will be important to demonstrate reduction in fracture risk as well as gain in BMD.

The study was sponsored by Amgen, Astellas, and UCB. Cosman disclosed grants/research support from Amgen, and consulting fees and speaker activities for Amgen and Radius Health. Bolster disclosed relationships with AbbVie, Corbus, Cumberland, Gilead, Johnson & Johnson, and Pfizer.

SOURCE: Cosman F et al. Arthritis Rheumatol. 2020;72(suppl 10), Abstract 1973.

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