Abivax : FIRST PATIENT DOSED IN THREE-MONTH COHORT OF PHASE 2A STUDY OF ORAL ABX464 IN HIV-SUPPRESSED PATIENTS

Trial Will Evaluate Effects of ABX464 on HIV reservoirs in gut tissue and blood Study measures response rate over time

ABX464 is a first-in-class oral, small molecule anti-viral drug-candidate discovered by ABIVAX. It inhibits HIV replication through a unique mechanism of action and also has a strong anti-inflammatory effect as demonstrated in preclinical testing. Specifically, ABX464 inhibits the activity of REV, a key HIV protein, thereby promoting HIV RNA splicing and thus inhibiting HIV replication through a novel mechanism (i.e., the modulation of RNA splicing) that may not lead to the development of resistance.

In the first cohort, 12 patients with HIV infection received 150mg of ABX464 for 28 days in addition to their antiretroviral treatment. Rectal biopsies were collected at pre-specified intervals to quantify the change in viral load and level of inflammation in those HIV reservoirs over time. Initial results of the first cohort are expected in the first week of October.

The second cohort of 12 patients will receive 50mg of ABX464 for three months in addition to their antiretroviral treatment. Similar to the first cohort, patients will undergo rectal biopsies at pre- specified intervals to quantify the change in viral load and level of inflammation over the three-month time period. The first patient of the second cohort was dosed at the Germans Trias i Pujol University Hospital Badalona in Barcelona, Spain. Initial results of the second cohort are expected in the second quarter of 2018.

Jean-Marc Steens, M.D., chief medical officer of ABIVAX, commented: "The second cohort will give us important information on the ability of ABX464 to further reduce the HIV reservoirs and improve the response rate over a longer time period. We are grateful to the Barcelona center of excellence and their patients for their continued support in further developing this molecule targeting the HIV reservoir, potentially leading towards a functional cure."

About ABIVAX (www.abivax.com)

ABIVAX is an innovative biotechnology company focused on targeting the immune system to eliminate viral disease. ABIVAX leverages three technology platforms for drug discovery: an anti-viral, an immune enhancement, and a polyclonal antibody platform. ABX464, its most advanced compound, is currently in Phase 2 clinical trials for providing a sustained viral remission or functional cure for patients with HIV/AIDS. It is a first-in-class oral small anti-viral molecule which blocks HIV replication through a unique mechanism of action and also has a strong anti-inflammatory effect. In addition, ABIVAX is advancing a clinical stage immune enhancer as well as multiple preclinical candidates against additional viral targets (e.g. Respiratory Syncytial Virus (RSV), Influenza and Dengue), and several of these compounds are planned to enter clinical development within the next 18 months. ABIVAX is

listed on Euronext compartment B (ISIN: FR0012333284 - Mnémo: ABVX). More information on the company is available at www.abivax.com.

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