Safety signal derails expected approval of Amgen bone drug
- Amgen no longer expects to win approval for its closely watched osteoporosis drug romosozumab this year, after an unexpected cardiovascular safety signal was picked up in a Phase 3 comparator trial testing the bone-building drug against the generic alendronate.
- The Thousand Oaks, CA-based drugmaker, along with its partner UCB, had already submitted romosuzumab to the Food and Drug Administration for approval based on positive findings from another late-stage study which read out last year. But the regulator will now consider the new data in its review, delaying a decision and adding uncertainty around what was seen as a future growth driver for the biotech.
- The surprising setback pushed down Amgen stock by about 2% Monday morning, while its partner UCB saw a heavier sell-off on a Belgian stock exchange. The news was a welcome lift for Radius Health, however, which recently won approval for its competing osteoporosis drug Tymlos (abaloparatide). Shares in Radius climbed by nearly 10%.
Troubles with romosuzumab could up the scrutiny on Amgen's growth prospects moving forward. The biotech faces a more challenging market for its top-earners Enbrel (etanercept) and Neulasta (pegfilgrastim), while sales of its PCSK9 blockbuster hopeful Repatha (evolocumab) continue to grow slowly.
Romosuzumab, dubbed Evenity by Amgen in anticipation of a launch later this year, would have added momentum to Amgen's existing bone health franchise and complemented the fast-growing Prolia (denosumab).
In the ARCH study, postmenopausal women in the treatment arm received subcutatneous romosuzumab for 12 months followed by another 12 months of once-weekly alendronate. After two years, women treated with romosuzumab saw a 50% reduction in relative risk of a new vertebral fracture, compared to those who received just alendronate over the period.
Romosuzumab also reduced the relative risk of clinical fracture and non-vertebral fractures, hitting both its primary and secondary endpoints.
But after 12 months, the incidence of positively adjudicated cardiovascular serious adverse events was 2.5% in the treatment arm, compared to 1.9% in the alendronate group. This imbalance had not been seen in the previous Phase 3 FRAME study, which compared romosuzumab to placebo.
Executives from Amgen and UCB both said the results would be discussed with global regulatory authorities, while noting the efficacy of romosuzumab. No timeline was given on how long the new data may delay a decision on approval from the FDA. Submission of the drug to the European Medicines Agency will continue as planned, Amgen said.
The delay and new uncertainty around romosuzumab gives fresh breathing room to Radius, which will be trying to steal market share from Prolia and Eli Lilly's Forteo (teriparatide). Radius hopes to quickly build uptake for Tymlos, although the drug will carry a warning of the risk of osteosarcoma.
Radius priced Tymlos at a significant discount to Forteo, which could help it launch quickly — particularly now that romosuzumab is derailed for at least two quarters.
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