(ARGS) New Clinical Data for AGS-004 Patient-Specific Immunotherapy in HIV

Clinical Results Showing Induction of Memory T Cell Responses in Acute and Chronic HIV Infected Patients Presented at Conference on Retroviruses and Opportunistic Infections (CROI) Meeting in Boston

DURHAM, N.C., March 4, 2014  — Argos Therapeutics Inc. (Nasdaq:ARGS), a biopharmaceutical company focused on the development and commercialization of fully personalized immunotherapies for the treatment of cancer and infectious diseases using its Arcelis™ technology platform, today presented data from clinical studies of AGS-004, the company’s patient-specific immunotherapy currently in development for the treatment of HIV infection. Results were presented in two poster presentations at the Conference on Retroviruses and Opportunistic Infections (CROI) meeting in Boston.

The first poster, entitled Immune Function and Viral Load Post-AGS-004 Administration to Chronic HIV Subjects Undergoing STI, presents new findings from a Phase 2a clinical trial to assess safety and efficacy of AGS-004 during a 12-week antiretroviral therapy (ART) structured treatment interruption (STI) in chronic HIV-1 infected patients. The goal of intervention was to induce long-term immunity against each patient’s unique viral variants and determine the impact on viral load control after stopping ART drug therapy. Results showed that AGS-004 induced anti-HIV T memory stem cell-like immune responses (T_SCM) that were associated with a longer time to viral rebound after ART treatment interruption. In addition, the longer time to viral rebound was also associated with lower expression of the checkpoint inhibitor PD-1 on activated CD8+ T cells.

“This is the first demonstration that AGS-004 can induce anti-viral T_SCM-like immune responses in chronic HIV patients and that these responses are associated with viral load control in the absence of ART drugs. Establishing long-lasting immune memory is a critical component of durable viral load control and bodes well for our planned eradication and functional cure studies,” said Charles Nicolette, PhD, chief scientific officer and vice president of research and development for Argos Therapeutics.

The second poster, entitled Immunogenicity of AGS-004 Dendritic Cell Therapy in Patients Treated During Acute HIV Infection, highlights results from an open-label, single arm study where treatment with AGS-004 was administered to patients who initiated ART within 45 days of primary HIV infection. The study was led by David Margolis, MD, Joseph Eron, MD, Nancie Archin, PhD, and Cynthia Gay, MD, faculty at the University of North Carolina School of Medicine, and Charles B. Hicks, MD, professor of medicine at Duke University Medical Center. Results showed that new anti-HIV memory T cell immune responses were induced in all six patients treated. One patient was able to maintain sufficient viral control while off ART drugs for approximately five months and another patient continues ART treatment interruption after nearly nine months. Additionally, three of six patients had decreases in circulating CD4+ T cells containing HIV DNA of 25%, 47% and 63%, respectively, when measured after three doses of AGS-004 while on ART.

“This study demonstrates that AGS-004 can induce anti-viral memory T cell responses in acute patients and may result in depletion of persistent HIV infection in ART-suppressed patients in combination with anti-latency therapy,” said Dr. Margolis.

The Argos AGS-004 clinical research program is supported by funding from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under Contract No. N01-AI-60019.

About the Arcelis™ Technology Platform

Arcelis is a fully personalized immunotherapy technology that captures mutated and variant antigens that are specific to each patient’s disease. It is designed to overcome immunosuppression by producing a durable memory T cell response without adjuvants that may be associated with toxicity. The technology is potentially applicable to a wide range of different cancers and infectious diseases and is designed to overcome many of the manufacturing and commercialization challenges that have impeded other personalized immunotherapies.

The Arcelis process uses only a small tumor or blood sample and the patient’s own dendritic cells, which are collected and optimized following a single leukapheresis procedure. The proprietary process uses RNA isolated from the patient’s disease sample to program dendritic cells to target disease antigens. The activated, antigen-loaded dendritic cells are then formulated into the patient’s plasma and administered via intradermal injection.

About Argos Therapeutics

Argos Therapeutics is a biopharmaceutical company focused on the development and commercialization of fully personalized immunotherapies for the treatment of cancer and infectious diseases using its Arcelis™ technology platform. Argos’ most advanced product candidate, AGS-003, is in a pivotal Phase 3 trial for the treatment of mRCC, and the company plans to have data from its Phase 2b trial of AGS-004 for the treatment of HIV in mid- 2014. For more information about Argos Therapeutics, visit www.argostherapeutics.com.

Forward Looking Statement

Statements contained in this press release regarding matters that are not historical facts are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Risks are described more fully in Argos Therapeutics’ filings with the Securities and Exchange Commission, including without limitation its most recently filed reports on Form 8-K and other documents subsequently filed with or furnished to the Securities and Exchange Commission. The investigative immunotherapies discussed in this press release are not approved by the U.S. Food and Drug Administration (FDA) and no conclusions should be drawn regarding their safety or effectiveness. All forward-looking statements contained in this press release speak only as of the date on which they were made. Argos undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

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