News Releases

Pfenex to Present at Upcoming Industry Conference on September 26

SAN DIEGO, September 19, 2014 - Pfenex Inc. (NYSE MKT: PFNX), a clinical-stage biotechnology company engaged in the development of high-value and difficult to manufacture proteins including biosimilar therapeutics, today announced that it will be presenting at the 21st Annual NewsMakers in the Biotech Industry conference in New York. Bertrand Liang, chief executive officer of Pfenex, will provide an overview of the company’s development programs and business strategy on Friday, September 26, 2014 at 10:00 a.m. EDT/7:00 a.m. PDT. A live audio webcast and archive of the presentation will be available in the Investor Relations section of the Pfenex website at www.pfenex.com.

Pfenex has used, and intends to continue to use, its Investor Relations website (http://pfenex.investorroom.com), as means of disclosing material non-public information and for complying with its disclosure obligations under Regulation FD. For more information, visit (http://pfenex.investorroom.com).

About Pfenex Inc.

Pfenex Inc. is a clinical-stage biotechnology company engaged in the development of high-value and difficult to manufacture proteins including biosimilar therapeutics. The company’s lead product candidate is PF582, a biosimilar candidate to Lucentis (ranibizumab), for the potential treatment of patients with retinal diseases. Pfenex has leveraged its Pfēnex Expression Technology® platform to build a pipeline of product candidates and preclinical products under development including other biosimilars, as well as vaccines, generics and next generation biologics. For additional information please visit the Pfenex website at www.pfenex.com.

Company Contact:

Paul Wagner, Ph.D.

Chief Financial Officer

(858) 352-4333

pwagner@pfenex.com

Investor Relations Contact:

Westwicke Partners, LLC

Robert H. Uhl

Managing Director

(858) 356-5932

robert.uhl@westwicke.com