Ultragenyx Stumbles Over Late-Stage Trial

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Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) shares took a turn for the worse on Wednesday after results from its late-stage trial in patients with GNE myopathy (GNEM) did not live up to expectations. The company was conducting its Phase 3 study evaluating aceneuramic acid extended release (Ace-ER), but it seems that it’s back to the drawing board.

Specifically, the study did not achieve its primary endpoint of demonstrating a statistically significant difference in the upper extremity muscle strength composite score compared to placebo. The study also did not meet its key secondary endpoints.

There were three prespecified key secondary endpoints, including the lower extremity muscle strength composite score as measured by hand-held dynamometry, physical functioning using the Mobility domain of the GNE myopathy-functional activity scale, and a measure of muscle strength in knee extensors. As mentioned, the study did not meet any of these key secondary endpoints.

Adverse events were generally balanced between Ace-ER and placebo, and safety was consistent with previously released Ace-ER data. Ultragenyx plans to discontinue further clinical development of Ace-ER.

As a result, the company plans to terminate the development program based on these results and will be working with investigators and patients on a reasonable transition plan for patients still on Ace-ER.

Emil D. Kakkis, M.D., Ph.D., CEO and president of Ultragenyx, commented:

We are disappointed by these results, as we had hoped that Ace-ER would offer a new option for GNEM patients. We would like to thank the patients, caregivers, and investigators involved in the Ace-ER development program. This outcome does not affect our overall strategy, as the company moves forward with multiple preclinical and clinical programs and regulatory filings.

Shares of Ultragenyx traded Wednesday morning at $51.60, down more than 12% on the day. The consensus analyst price target is $79.80 and a 52-week trading range is $51.67 to $91.35.