Proteostasis Therapeutics Announces Pricing of Public Offering of Common Stock

CAMBRIDGE, Mass., Sept. 09, 2016 (GLOBE NEWSWIRE) — Proteostasis Therapeutics, Inc. (NASDAQ:PTI), a biopharmaceutical company developing small molecule therapeutics to treat diseases caused by dysfunctional protein processing such as cystic fibrosis, today announced the pricing of its follow-on public offering of 5,000,000 shares of its common stock at a public offering price of $13.00 per share, before the underwriting discount. All of the common stock is being offered by Proteostasis Therapeutics, Inc. In addition, the company has granted the underwriters a 30-day option to purchase up to an additional 750,000 shares of its common stock at the public offering price, less the underwriting discount. The offering is expected to close on September 14, 2016 subject to customary closing conditions.

Leerink Partners and RBC Capital Markets are acting as joint book-running managers. H.C. Wainwright & Co. is acting as lead manager and Baird is acting as co-manager.

A registration statement on Form S-1 relating to the securities being sold in the offering was declared effective by the Securities and Exchange Commission on September 8, 2016. This offering is being made only by means of a prospectus. Copies of the final prospectus relating to this offering may be obtained, when available, by contacting: Leerink Partners LLC, Attention: Syndicate Department, One Federal Street, 37th Floor, Boston, MA 02110, or by email at syndicate@leerink.com, or by phone at (800) 808-7525, ext. 6142; or RBC Capital Markets, LLC, Attention: Equity Syndicate, 200 Vesey Street, 8th Floor, New York, NY 10281, Telephone: (877) 822-4089, Email: equityprospectus@rbccm.com.

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 state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Proteostasis Therapeutics, Inc.

Proteostasis Therapeutics, Inc. is a biopharmaceutical company dedicated to the discovery of groundbreaking therapies to treat diseases caused by dysfunctional protein processing, such as cystic fibrosis (CF). Headquartered in Cambridge, MA, the Proteostasis Therapeutics team focuses on identifying therapies that modulate the proteostasis imbalance in cells and restore protein function.

Forward-Looking Statements
This release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements about the timing of the closing. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. For a discussion of risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in our most recent Annual Report on Form 10-K or the fiscal year ended December 31, 2015 and our Quarterly Report on Form 10-Q for the quarter ended June 30, 2016, the preliminary prospectus related to the public offering, as well as discussions of potential risks, uncertainties, and other important factors in our subsequent and future filings with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and Proteostasis Therapeutics, Inc. undertakes no duty to update this information, whether as a result of new information, future events or otherwise, unless required by law.

CONTACT: Media Contact: 
Katie Engleman, Pure Communications, Inc.

(910) 509-3977 
katie@purecommunicationsinc.com

Investor Contact:
Luke Heagle, Pure Communications, Inc.
(910) 726-1372
luke@purecommunicationsinc.com