Altus Pharmaceuticals Announces Closing of $88.5 Million Public Offering.

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 that it has completed the previously announced underwritten public offering of 6,000,000 shares of its common stock at a public offering price of $14.75 per share. The aggregate gross proceeds from the offering were approximately $88.5 million before deducting underwriting discounts and commissions and offering expenses. Altus Pharmaceuticals has granted the underwriters a 30-day option to purchase up to an additional 900,000 shares of common stock to cover over-allotments, if any. All of the shares were offered by Altus Pharmaceuticals. Merrill Lynch & Co. and Morgan Stanley & Co. were joint book-running managers for the offering. Cowen and Company and Leerink Swann & Company were co-managers for the offering.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such jurisdiction. Copies of the prospectus may be obtained from Morgan Stanley & Co. Incorporated, 180 Varick Street, New York, NY 10014, Attn: Prospectus Department or by email at [e-mail] or from Merrill Lynch, Pierce, Fenner & Smith Incorporated, 4 World Financial Center, New York, New York 10080.

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 is listed on the Nasdaq Global Market under the symbol ALTU.

Safe Harbor Statement

Certain statements in this news release concerning Altus Pharmaceuticals' business are considered "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. 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 Pharmaceuticals might make or by known or unknown risks and uncertainties, including, but not limited to uncertainties as to whether the over-allotment option granted in the public offering will be exercised. 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 Pharmaceuticals' reports filed with the Securities and Exchange Commission, including its Annual Report on Form 10-K for the fiscal year ended December 31, 2006, as may be updated in its quarterly and current reports. However, Altus Pharmaceuticals undertakes no obligation to publicly update forward-looking statements, whether because of new information, future events or otherwise.