Altus Pharmaceuticals Announces Presentation of ALTU-238 Phase II Data at International Congress of Growth Hormone and Insulin-Like Growth Factor Research Societies.

CAMBRIDGE, Mass. -- Altus Pharmaceuticals Inc. (NASDAQ: ALTU), a biopharmaceutical company focused on oral and injectable protein therapeutics for patients with gastrointestinal and metabolic disorders, announced today the presentation of results from its Phase II study of its product candidate ALTU-238 at The Third International Congress of the Growth Hormone Research Society and the Insulin-like Growth Factor Research Society, which is taking place this week in Kobe, Japan. ALTU-238 is being developed as a subcutaneously administered, once-per-week formulation of human growth hormone that employs AltuseIU proprietary protein crystallization and formulation technology.

The results of this trial demonstrated a pharmacokinetic and pharmacodynamic profile that the Company believes is supportive of an ALTU-238 once-per-week dosing regimen for growth hormone deficient adults. The study identified doses of ALTU-238 that maintained IGF-1 levels within the normal range for age and gender over the course of the study. Once-per-week dosing of ALTU-238 appeared to result in a consistent, linear dose response of hGH and IGF-1 levels in the blood.

Lead investigator Randall J. Urban, M.D., Chief of Medicine at The University of Texas Medical Branch in Galveston, Texas, commented, "The standard treatment for growth hormone deficiency typically requires multiple injections per week, a regimen that can be inconvenient and painful, which may lead to poor patient compliance. ALTU-238 promises to improve patient quality of life with better dosing as a potential once-per-week treatment, and we believe it represents a significant milestone in the treatment of growth hormone disorders."

The primary objectives of the trial were to determine the safety and tolerability of ALTU-238, as well as to evaluate its pharmacokinetic and pharmacodynamic profile. Thirteen growth hormone deficient adult patients were randomized to receive three weekly subcutaneous injections, using a fine 30-gauge needle, of either 5.6 mg or 11.2 mg of ALTU-238. Pharmacokinetics and pharmacodynamics were measured for growth hormone, insulin-like growth factor-1 (IGF-1), and bone alkaline phosphatase (BAP) using samples taken following the first and third subcutaneous injections. Safety assessments included fasting serum insulin and glucose levels as well as postprandial glucose.

There were no reported serious adverse events or dropouts due to adverse events. The most frequent adverse event reported was mild injection pain. Typical adverse events associated with growth hormone treatment, including myalgia, edema, and arthralgia, were uncommon. Injection site reactions were most commonly associated with erythema, which diminished by the third injection. No subject tested positive for anti-growth hormone antibodies in this study.

About ALTU-238

ALTU-238 is a long-acting subcutaneous formulation of recombinant human growth hormone that employs Altus' proprietary protein crystallization and formulation technology. Altus' technology preserves the structure of the human growth hormone molecule without the need for polymers or encapsulation and enables administration through a fine gauge needle. Recombinant human growth hormone is approved for treating multiple growth disorders in children, adolescents and adults. Global sales of recombinant human growth hormone were approximately $2.4 billion in 2005.

About Growth Hormone Deficiency and Growth Failure

Growth hormone disorders occur when the production of growth hormone, secreted via the hypothalamiceIpituitary axis (GHRH-GH-IGF1), is disrupted. Growth hormone plays a critical role in stimulating bone growth and development and it is involved in the production of muscle and in the breakdown of fats. In children, when there is a complete absence of growth hormone, severe growth retardation results. When there is a partial deficiency of growth hormone in children, short stature results. Recombinant human growth hormone (rhGH) products are currently approved to treat multiple growth disorders, including pediatric and adult growth hormone deficiency, Turner Syndrome, chronic renal insufficiency, idiopathic short stature, Prader-Willi Syndrome, short children born small for gestational age, short bowel syndrome and muscle wasting in patients with HIV.

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.

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, the timing of a Phase III clinical trial for ALTU-238, and the ability of Altus' proprietary protein crystallization technology to effectively deliver growth hormone therapy through a once-weekly injection using a fine gauge needle. 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-K for the fiscal year ended December 31, 2005. However, Altus undertakes no obligation to publicly update forward-looking statements, whether because of new information, future events or otherwise.