Aceneuramic acid

Program to be externally funded by a venture philanthropy agreement through clinical proof-of-concept, including the Phase 1/2 study planned to begin in the second half of 2026 NOVATO, Calif., March 30, 2026 (GLOBE NEWSWIRE) -- Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) today announced that the U.S. Food and Drug Administration (FDA) has cleared the Investigational New Drug (IND) application for UX016, an investigational small molecule prodrug of sialic acid (SA) being evaluated as a substrate replacement therapy for GNE myopathy (GNEM). GNEM is a rare, severely debilitating, inherited neuromuscular disorder caused by mutations in the GNE gene that lead to deficient SA production. The UX016 program is externally funded by a patient group through clinical proof-of-concept, including a Phase 1/2 study expected to begin in the second half of 2026. “People living with GNE myopathy face a profound and progressive loss of muscle function that affects every aspect of daily life, yet there are currently no approved treatment options to slow or alter the course of the disease,” said Coleman Kennedy, chief executive officer of the Neuromuscular Disease Foundation (NDF). “We appreciate Ultragenyx’s engagement with our community and are grateful for the innovative philanthropic support from others helping to move this program into the clinic. We look forward to continued collaboration as this study begins.” UX016 is a prodrug composed of SA and a hydrophobic fatty acid tail that enhances efficient delivery to muscle as compared to naturally occurring SA. UX016 aims to address challenges that have historically limited the efficacy of prior substrate replacement therapies. Based on preclinical data, the fatty acid tail improves UX016 distribution to muscle and other tissues and supports more efficient uptake and release of SA within muscle cells. “Advancing UX016 into the clinic marks an important milestone for the GNE myopathy community and reflects our commitment to developing an innovative approach to increase sialic acid uptake in muscle and to addressing the significant medical needs faced by this community,” said Emil Kakkis, M.D., Ph.D., chief executive officer and president of Ultragenyx. “We are pleased to initiate this work with the support of an innovative external funding model and look forward to working closely with physicians and the patient community as we evaluate UX016 in a Phase 1/2 study.” The planned first-in-human, Phase 1/2 study will enroll approximately 24 adults ages 18 to 55 years with GNEM in the United States. The study, expected to begin in the second half of 2026, will evaluate the safety and efficacy of UX016. The study will also evaluate the pharmacokinetics and delivery to muscle at two doses 3:1 relative to placebo over the first 12 weeks and then will evaluate upper and lower muscle strength, patient reported outcomes relevant to GNEM, and other functional measures through Week 48 of treatment. For more information, patients can contact TrialRecruitment@ultragenyx.com . About GNE Myopathy GNE myopathy (GNEM), also known as hereditary inclusion body myopathy (HIBM) and Nonaka Myopathy, is a rare, severely debilitating, adult-onset autosomal recessive neuromuscular disease caused by a defect in the biosynthetic pathway for sialic acid (SA). The body's inability to produce adequate SA leads to progressive muscle wasting and severe disability. Patients typically become non-ambulatory and ultimately dependent on caregivers for most activities of daily living due to loss of upper and lower extremity muscle function. GNEM is estimated to affect approximately 10,000 people in commercially accessible geographies, and there is currently no approved therapy in the United States. About UX016 UX016 is an investigational small-molecule prodrug composed of sialic acid (SA; also known as N‑acetylneuraminic acid [NANA]) and a C16 fatty acid tail designed to improve biodistribution to target tissues, like muscle, more effectively and efficiently than free SA. By increasing SA availability in muscle, UX016 is expected to restore sialylation of muscle glycoproteins and glycolipids and has the potential to slow or alter GNEM disease progression. In a GNEM (HIBM) mouse model, repeat subcutaneous administration of UX016 increased total, free and bound SA concentrations across multiple skeletal muscles and restored SA levels toward near normal. About Ultragenyx Ultragenyx is a biopharmaceutical company committed to bringing novel therapies to patients for the treatment of serious rare and ultra-rare genetic diseases. The company has built a diverse portfolio of approved medicines and treatment candidates aimed at addressing diseases with high unmet medical need and clear biology, for which there are typically no approved therapies treating the underlying disease. The company is led by a management team experienced in the development and commercialization of rare disease therapeutics. Ultragenyx’s strategy is predicated upon time- and cost-efficient drug development, with the goal of delivering safe and effective therapies to patients with the utmost urgency. For more information on Ultragenyx, please visit the company's website at: . Forward-Looking Statements and Use of Digital Media Except for the historical information contained herein, the matters set forth in this press release, including statements related to Ultragenyx’s expectations and projections regarding the development of UX016, the timing, initiation and design of the planned Phase 1/2 clinical study, the anticipated enrollment and evaluation of patients, the potential safety, tolerability and efficacy of UX016, the ability of UX016 to address limitations observed with prior approaches, the expected benefits of the external philanthropic funding arrangement, future regulatory interactions, and the potential therapeutic impact of UX016 for patients with GNE myopathy, are forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements involve substantial risks and uncertainties that could cause our clinical development programs, collaboration with third parties, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, the uncertainty of clinical drug development; risks related to the initiation, conduct, timing, enrollment and results of clinical trials; the possibility that safety, tolerability or efficacy data from preclinical studies or early‑stage clinical trials may not be predictive of future clinical results; the risk that UX016 may not demonstrate a favorable benefit‑risk pro achieve clinical proof‑of‑concept; delays or challenges in regulatory interactions or approvals; the company’s ability to execute the planned clinical development program within the expected timelines or funding parameters; risks related to reliance on third parties, including clinical trial sites, investigators and manufacturers; manufacturing and supply risks; smaller than anticipated patient populations or market opportunities; competition from other therapies or approaches; and other risks that could affect the sufficiency of available funding, the company’s development plans, or the commercial potential of UX016. Ultragenyx undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of Ultragenyx in general, see Ultragenyx's Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 18, 2026, and its subsequent periodic reports filed with the SEC. In addition to its SEC filings, press releases and public conference calls, Ultragenyx uses its investor relations website and social media outlets to publish important information about the company, including information that may be deemed material to investors, and to comply with its disclosure obligations under Regulation FD. Financial and other information about Ultragenyx is routinely posted and is accessible on Ultragenyx’s Investor Relations website ( ) and LinkedIn website ( ). Ultragenyx Contacts Investors Joshua Higa ir@ultragenyx.com Media Jess Rowlands media@ultragenyx.com

March 23, 2017 By Alex Keown , BioSpace.com Breaking News Staff NOVATO, Calif. – Shares of Ultragenyx Pharmaceuticals are down more than 8 percent today after the company announced its Phase II drug UX007 to treat seizures failed to meet trial goals. In its announcement, Ultragenyx said UX007 did not reduce the frequency of number of observable seizures among patients during an eight-week period of treatment. The company said treatment with UX007 did show a reduction in absence seizures captured on EEG, but not observable seizures captured by diary. Patients treated with UX007 demonstrated a reduction of 13.4 percent in overall seizure frequency relative to placebo, the company said in its announcement. During the Phase II trial, patients kept a daily seizure diary to capture observable seizures in patients. An electroencephalography (EEG) was used at baseline and week eight to capture absence seizures. Dosing was initiated over a two-week titration period until the patient reached the target dose of 35 percent of total daily calories from UX007, the company said. UX007 is a highly purified, pharmaceutical-grade synthetic seven carbon fatty acid triglyceride intended to provide patients with medium-length, odd-chain fatty acids that can be metabolized to increase intermediate substrates in the Krebs cycle, a key energy-generating process, according to company information. The drug is being developed to treat seizures in patients with glucose transporter type-1 deficiency syndrome (Glut1 DS). Glut1 DS is a severely debilitating disease characterized by seizures, developmental delay, and movement disorders. Glut1 DS is caused by a genetic defect in the transport of glucose into the brain. There are currently no FDA approved treatments specific to Glut1 DS. Emil D. Kakkis , president and chief executive officer of Ultragenyx , said the Phase II data showing the 13.4 percent reduction in seizures suggests UX007 has a “clinically meaningful effect in Glut1DS patients with absence seizures.” Kakkis said the company is looking forward to continue studying UX007 in Ultragenyx’s Phase III study in Glut1 DS patients with movement disorders. He said the company will continue to evaluate its options for UX007 in the indication for seizures. There were no deaths and no treatment-related serious adverse events during the trial. Two of the 36 enrolled patients discontinued treatment during the eight-week placebo-controlled period. During the trial, 12 patients discontinued use during the extension period. Two patients discontinued due to adverse events, four patients due to tolerability reasons and eight for compliance or study burden issues, the company said. Ultragenyx could get a rebound if news is positive regarding its Phase III enzyme replacement therapy candidate rhGUS for the treatment of Mucopolysaccharidosis 7. In July, the company announced the late-stage study met its primary endpoint of reducing urinary GAG (dermatan sulfate) excretion after 24 weeks of treatment. Ultragenyx is set to seek regulatory approval with the U.S. Food and Drug Administration and the European Medicines Agency later this year. In November, Ultragenyx was forced to shelve plans for a quick approval of its investigational Aceneuramic Acid Prolonged Release (Ace-ER) for the treatment of adult patients with GNE Myopathy. The company announced it withdrew a conditional Marketing Authorization Application after a Phase II study “did not provide a sufficient amount of evidence to support an approval” at the time it was received. The company has launched a Phase III trial and plans to submit another MAA to the EMA after data is available later this year.