Why Did RARE Stock Plunge Over 41% Today?

Ultragenyx Pharmaceutical announced disappointing results from its Phase 3 studies for the setrusumab (UX143) in the Osteogenesis Imperfecta (OI) program.

• The company said that results from the Phase 3 Orbit and Cosmic studies for an experimental drug designed to help people with brittle bone disease did not significantly reduce annualized clinical fracture rates.
• Both studies showed improvements in bone mineral density, the company said. 
• Ultragenyx also noted that it will reduce expenses significantly after evaluating its planned operations.

Ultragenyx Pharmaceutical Inc. (RARE) shares plunged over 41% on Monday after the company announced disappointing results from its Phase 3 studies for its experimental drug designed to help people with brittle bone disease.

The company said that results from the Phase 3 Orbit and Cosmic studies for setrusumab (UX143) in Osteogenesis Imperfecta (OI) did not significantly reduce annualized clinical fracture rates compared to placebo or bisphosphonates, respectively. However, both studies showed improvements in bone mineral density, the company said.

The firm also said it will significantly reduce expenses after evaluating its planned operations.

Trial Details

In the Orbit study, participants showed substantial improvements in bone mineral density compared with the placebo group. However, that did not result in a significant reduction in annualized fracture rates, since the placebo group also had a low fracture rate, the company noted.

In the Cosmic study, which included pediatric patients, the baseline fracture rate was substantially higher than in the Orbit patient group. While the study showed improvements in bone mineral density and a reduction in annualized fracture rate compared to bisphosphonate-treated patients, the results were not statistically significant.

“We are surprised and disappointed by these results given the promising data from our Phase 2 study and the lack of approved treatment options available to patients with OI who live with significant pain, disability, and disease burden,” said Emil Kakkis, chief executive officer and president of Ultragenyx. “We continue to explore the data to gain deeper understanding of the findings.”

How Did Stocktwits Users React?

On Stocktwits, retail sentiment around RARE shares jumped to ‘extremely bullish’ from ‘bearish’ territory over the past day, while message levels jumped to ‘extremely high’ levels at the time of writing. The stock was also among the top trending tickets on the platform.

Shares of RARE are down over 51% in the past year.

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