Hookipa and Gilead Enter into a Collaboration and License Agreement to Develop Immunotherapies Against HIV and Hepatitis B

• Hookipa and Gilead will jointly develop therapeutics against HIV and Hepatitis B infections
• Hookipa and Gilead will jointly research and Hookipa will manufacture arenavirus-based vectors for clinical development by Gilead
• The deal expands the relationship between Hookipa and Gilead following Gilead's participation in Hookipa's Series C financing in December 2017
• Total potential deal value exceeds $400 million, including upfront and milestone payments, plus research and development funding

Vienna, Austria and Foster City, CA, 5 June 2018 - Hookipa Biotech AG ("Hookipa"), a clinical-stage biotech company pioneering an innovative class of active immunization therapies for oncology and infectious diseases and Gilead Sciences, Inc., ("Gilead"), a research-based biopharmaceutical company that discovers, develops and commercializes innovative medicines in areas of unmet medical need, today announced that they have entered into a research collaboration and license agreement that grants Gilead exclusive rights to Hookipa's TheraT® and Vaxwave® arenavirus vector-based immunization technologies for two major chronic infectious disease indications, hepatitis B virus (HBV) and human immunodeficiency virus (HIV).

Under the terms of the agreement, Gilead will provide an upfront payment of $10 million. Additionally, Hookipa will be eligible to receive milestone payments based upon the achievement of specified development, regulatory, and commercial milestones up to a total of more than $400 million. Gilead will fund all research and development activities. Hookipa will also be eligible to receive tiered royalties on net sales.

"Gilead, a world leader in innovative therapies against major viral diseases, is the ideal partner for us to drive our pipeline development in this area for the benefit of patients in need. This partnership is strong recognition of our unique immunization technology, and helps us concentrate our own energy and resources on immuno-oncology," commented Joern Aldag, Chief Executive Officer of Hookipa. "The collaborative HIV and HBV programs nicely complement our significant efforts in the infectious disease area with an exciting proprietary prophylactic CMV vaccine."

"Gilead is committed to advancing innovative approaches directed at functional cures against HIV and HBV," said Bill Lee, PhD, Executive Vice President of Research, Gilead. "We are convinced that Hookipa's unique therapeutic vaccine technology, which has demonstrated excellent safety and immunogenicity in Phase 1 clinical studies, has strong potential to have synergistic effect with other Gilead cure efforts in both of these diseases areas. Our ultimate long-term goal is to eliminate the need for life-long antiviral therapy for millions of patients around the world."

About Gilead Sciences, Inc. Gilead Sciences, Inc. is a research-based biopharmaceutical company that discovers, develops and commercializes innovative medicines in areas of unmet medical need. The company strives to transform and simplify care for people with life-threatening illnesses around the world. Gilead has operations in more than 35 countries worldwide, with headquarters in Foster City, California.

About Hookipa Biotech Hookipa Biotech is a clinical stage company developing next-generation immunotherapies for infectious diseases and cancer using novel proprietary arenavirus vector platforms.

Hookipa´s Vaxwave® technology presents a completely new replication-defective viral vector platform designed to overcome the limitations of current technologies. Vaxwave® is based on lymphocytic choriomeningitis virus (LCMV). In this vector the gene encoding the LCMV envelope protein, normally responsible for virus entry into target cells, has been deleted and replaced with an antigen of interest. The resulting vectors infect dendritic cells and stimulate very potent and long-lasting immune response, however they cannot replicate and are therefore non-pathogenic and inherently safe.

Hookipa's TheraT® platform is based on an attenuated replicating arenavirus and is capable of eliciting the most potent T cell responses - a crucial step in treating patients with aggressive cancers. Significant pre-clinical data demonstrates that TheraT® is a powerful modality capable of turning "cold tumors hot" which should result in an additional layer of efficacy in the fight against solid tumors. Specifically, TheraT® has proven to be safe in animals as well as capable of eliciting uniquely potent antigen-specific CD8+ cytotoxic T cell responses and strong tumor control in mice. The first clinical trial with HB-201 targeting human papilloma virus-induced head and neck cancer is currently being prepared. This immuno-oncology technology is further being leveraged to target tumor self-antigens or shared neoantigens.

Find out more about Hookipa online at http://hookipabiotech.com/.

Gilead Forward-Looking Statements This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks, uncertainties and other factors, including the risk that the parties may not realize the potential benefits of this collaboration. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in Gilead's Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the U.S. Securities and Exchange Commission. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation to update any such forward-looking statements.

Issued for and on behalf of Hookipa Biotech AG by Instinctif Partners. For further information please contact:

Media enquiries Sue Charles/ Ashley Tapp Instinctif Partnershookipa@instinctif.com +44 (0)20 7866 7863

Gilead Investors Sung Lee, 650-524-7792 or Media Amy Flood, 650-522-5643