Hyperion Therapeutics Announces Data Published in Genetics in Medicine Showing Blood Ammonia and Glutamine as Predictors of Hyperammonemic Crises in Patients With Urea Cycle Disorders

BRISBANE, Calif., Jan. 12, 2015 (GLOBE NEWSWIRE) -- Hyperion Therapeutics, Inc. (Nasdaq:HPTX) today announced the online publication in Genetics in Medicine of analyses from four short-term switchover (SO) studies and three 12-month safety extension studies examining the relationships between fasting ammonia, daily ammonia exposure, and hyperammonemic crises (HAC) in adult and pediatric patients with urea cycle disorders (UCD.) The article titled "Blood ammonia and glutamine as predictors of hyperammonemic crises in patients with urea cycle disorder," is available online at http://www.nature.com/gim/journal/vaop/ncurrent/full/gim2014148a.html.

"Data analyzed from 100 UCD patients show that fasting ammonia correlates strongly and positively with total daily ammonia exposure and with the risk and rate of hyperammonemic crises, suggesting that patients with urea cycle disorders may benefit from tight ammonia control," said lead author, Brendan Lee M.D., Ph.D., Chair of the Department of Molecular and Human Genetics at Baylor College of Medicine, Houston, Texas. "While the results need prospective confirmation, this is important information for the UCD community."

The relationships between fasting ammonia, ammonia exposure, and hyperammonemic crises were analyzed in 100 patients with urea cycle disorders. Fasting ammonia correlated strongly with daily ammonia exposure (r = 0.764; P < 0.001). For patients with fasting ammonia concentrations <0.5 upper limit of normal (ULN), 0.5 to <1.0 ULN, and ≥1.0 ULN, the probability of a normal average daily ammonia value was 87%, 60%, and 39%, respectively, and 10.3%, 14.1%, and 37.0% of these patients, respectively, experienced ≥1 hyperammonemic crisis over a 12-month period. Time to first hyperammonemic crisis was shorter (P = 0.008) and relative risk (4.5×; P = 0.011) and rate (~5×, P = 0.006) of hyperammonemic crises were higher in patients with fasting ammonia ≥1.0 ULN vs. <0.5ULN. Relative risk was even greater (20×; P = 0.009) in patients ≥6 years old. A 10- or 25-µmol/l increase in cumulative ammonia exposure increased the risk of a hyperammonemic crisis by 50% and >200% (P < 0.0001), respectively, relative to those with no increase in ammonia exposure. The relationship between ammonia and hyperammonemic crisis risk appeared to be independent of treatment, age, urea cycle disorder subtype, dietary protein intake, or blood urea nitrogen.

About Urea Cycle Disorders

Urea cycle disorders, or UCDs, are a collection of inherited metabolic disorders in which affected patients suffer from high levels of systemic ammonia, a potent neurotoxin. Ammonia is produced via normal protein ingestion; the body normally detoxifies it by converting it through a series of enzymatic steps to urea, which is excreted in urine. Throughout their lives, UCD patients may experience recurrent hyperammonemic crises in which ammonia levels rise, and can develop complications ranging from nausea, vomiting and headache to coma and death.

About Hyperion Therapeutics

Hyperion Therapeutics, Inc. is a commercial-stage biopharmaceutical company committed to developing and delivering life-changing treatments for orphan diseases. The company's first commercial product, RAVICTI® (glycerol phenylbutyrate) Oral Liquid, was approved in February 2013 and is currently being marketed in the United States. The company also owns worldwide rights to BUPHENYL® (sodium phenylbutyrate) Tablets and Powder, which it markets in the U.S. The compound is also marketed internationally through business partners. In addition, the company is developing glycerol phenylbutyrate for the potential treatment of hepatic encephalopathy. For more information, please visit www.hyperiontx.com.

Forward-Looking Statement

To the extent that statements contained in this press release are not descriptions of historical facts regarding Hyperion, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Words such as "may," "will," "expect," "anticipate," "estimate," "intend," and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. Forward-looking statements contained in this press release include the statement that patients with urea cycle disorder may benefit from tight ammonia control. Hyperion undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties relating to the business of the company in general, see Hyperion's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 6, 2014, and any subsequent filings with the Securities and Exchange Commission.

CONTACT: Myesha Edwards Investor Relations and Corporate Affairs 650 745 7829

Source:Hyperion Therapeutics, Inc.