Zafgen Announces Proposed Offering of Common Stock

Zafgen Announces Proposed Offering of Common Stock

BOSTON, Mass., June 27, 2018 Zafgen, Inc., (Nasdaq:ZFGN), a clinical-stage biopharmaceutical company leveraging its

proprietary MetAP2 biology platform to develop novel therapies for patients affected by complex metabolic diseases, today announced that it has commenced an underwritten public offering of its common stock. All of the shares in the offering will be

sold by Zafgen. In addition, Zafgen intends to grant the underwriters a 30-day option to purchase up to an additional fifteen percent (15%) of the shares of common stock offered in the public offering.

Cowen and Company, LLC and Piper Jaffray & Co. are serving as joint book-running managers for the offering, and JMP Securities LLC and Wedbush

Securities Inc. are serving as co-lead managers. The offering is subject to market and other conditions, and there can be no assurance as to whether or when the offering may be completed, or as to the actual

size or terms of the offering.

The shares are being offered by Zafgen pursuant to a shelf registration statement that was previously filed with, and

subsequently declared effective by, the Securities and Exchange Commission (SEC). A preliminary prospectus supplement relating to and describing the terms of the offering will be filed with the SEC and will be available on the SEC s website at

www.sec.gov. Copies of the preliminary prospectus relating to the offering may be obtained, when available, by contacting Cowen and Company, LLC, c/o Broadridge Financial Services, 1155 Long Island Avenue, Edgewood, NY, 11717, Attn: Broadridge

Financial Solutions, by telephone at (631) 274-2806, or Piper Jaffray & Co., Attn: Prospectus Department, 800 Nicollet Mall, J12S03, Minneapolis, MN 55402, by telephone at (800) 747-3924, or by email at prospectus@pjc.com.

This press release shall not constitute an offer to sell or a solicitation

of an offer to buy these securities, 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.

Zafgen (Nasdaq:ZFGN) is a clinical-stage biopharmaceutical company leveraging its proprietary MetAP2 biology platform to develop novel therapies for patients

affected by complex metabolic diseases. Zafgen has pioneered the study of MetAP2 inhibitors in both common and rare metabolic disorders and is currently advancing programs for type 2 diabetes, Prader-Willi syndrome and liver diseases. The

Company s lead product candidate, ZGN-1061, a MetAP2 inhibitor for difficult-to-control type 2 diabetes, has successfully

completed the initial part of a Phase 2 clinical trial. Learn more at www.zafgen.com.

Media/Investor Relations Contacts:

Chief Financial Officer

Ten Bridge Communications