Altus Pharmaceuticals Reports ALTU-237 Phase 1 Clinical Trial Results.

CAMBRIDGE, Mass. -- Altus Pharmaceuticals Inc. (NASDAQ: ALTU) today reported top-line results from a Phase 1 clinical trial of ALTU-237 in healthy adult volunteers. ALTU-237 achieved a favorable safety profile - - the primary objective of the study. ALTU-237 is an orally-delivered crystalline formulation of an oxalate-degrading enzyme that is being developed for the treatment of hyperoxalurias and the possible prevention of recurrent kidney stones in individuals with a high risk or history of kidney stones. Currently, there are limited pharmacological treatments available for these diseases.

"In this study ALTU-237 was safe and well-tolerated in humans," commented Georges Gemayel, Ph.D., President and Chief Executive Officer at Altus Pharmaceuticals. "Healthy adult volunteers received a high oxalate diet and their urinary oxalate increased to the upper limit of the normal range. The ALTU-237 treatment did not result in a substantial or dose-dependent reduction in urinary oxalate levels. Healthy volunteers do not have the underlying pathophysiology of hyperoxaluria and therefore proof of concept for ALTU-237 can only be evaluated in hyperoxaluria patients."

Dr. Gemayel concluded, "Going forward, we will complete the analysis of the data and evaluate ALTU-237 in conjunction with our other pipeline programs."

The ALTU-237 Phase I clinical trial was a single-center, double-blind, placebo-controlled, dose escalating study. The primary objective was to evaluate the safety and tolerability of ALTU-237 in healthy adult volunteers. The study enrolled 58 healthy adults that were randomized to receive one of four doses of ALTU-237 (900; 3,600; 10,800 or 18,000 units per day) or placebo. All doses were well-tolerated and no severe adverse events were reported. Trial participants consumed a controlled, high oxalate diet and the effect of ATU-237 was measured by comparing the levels of urinary oxalate before and after the administration of ALTU-237 or placebo.

About Hyperoxaluria

Hyperoxaluria is a disease characterized by excessively high levels of oxalate in the urine, which can be a precursor to forming kidney stones. Hyperoxaluria can be caused by either excessive absorption of dietary oxalate (enteric hyperoxaluria) or increased endogenous production of oxalate (primary hyperoxaluria). When untreated, primary hyperoxaluria could lead to recurrent kidney stones and could contribute to renal failure. Ultimately, patients suffering from severe primary hyperoxaluria experience calcium oxalate deposits in their organs, which, if left untreated, could lead to death.

About Altus Pharmaceuticals Inc.

Altus Pharmaceuticals, headquartered in Cambridge, MA, is a biopharmaceutical company focused on the development and commercialization of oral and injectable protein therapeutics for patients with gastrointestinal and metabolic disorders. The Company's website is http://www.altus.com.

Safe Harbor Statement

Certain statements in this news release concerning Altus' business are considered "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, those relating to future development plans for ALTU-237. Any or all of the forward-looking statements in this press release may turn out to be wrong. They can be affected by inaccurate assumptions Altus might make or by known or unknown risks and uncertainties, including, but not limited to uncertainties as to the future success of ongoing and planned clinical trials; and the unproven safety and efficacy of products under development. Consequently, no forward-looking statement can be guaranteed, and actual results may vary materially. Additional information concerning factors that could cause actual results to materially differ from those in the forward-looking statements is contained in Altus' reports to the Securities and Exchange Commission, including its Annual Report on Form 10-Q for the period ended March 31, 2008. However, Altus undertakes no obligation to publicly update forward-looking statements, whether because of new information, future events or otherwise.