Bioversys ANNOUNCES FIRST SUBJECTS DOSED IN PHASE 1 CLINICAL TRIAL OF BV100 in CHInA

Ad hoc announcement pursuant to Art. 53 LR

• First healthy volunteer dosed with BV100 in China in mandatory Phase 1 trial
• Inclusion of Chinese clinical sites by H2 2026, into single global Phase 3 registration trial as planned

BioVersys AG, a multi-asset, clinical stage biopharmaceutical company focusing on research and development of novel antibacterial products for serious life-threatening infections caused by multi-drug resistant ("MDR") bacteria, announced today the dosing of the first subject in a Phase 1 clinical trial with BV100 in China.

The mandatory Phase 1 clinical trial in healthy volunteers in China precedes the inclusion of Chinese clinical sites by late 2026 into the single Global Phase 3 registration trial of BV100 in Ventilator Associated Bacterial Pneumonia (VABP). Recruitment in other geographies will start earlier.

BV100 is a novel intravenous formulation of rifabutin based on the newly identified mode of action for the active uptake of rifabutin into the Acinetobacter baumannii-calcoaceticus complex. BV100 is being developed for multi-drug resistant (“MDR”) hospital infections caused by Acinetobacter baumannii, including carbapenem resistant strains (CRAB).

While CRAB infections are a serious health threat throughout the world, incidence rates for Acinetobacter infections are particularly high in China and Asia. Combined with very high resistance rates of 60-80% to carbapenems, Acinetobacter baumannii is the leading cause of death attributable to antimicrobial resistance in China^[1]. Based on recent epidemiology data, BioVersys estimates that over 1 million patients annually are at risk of severe CRAB pneumonia and blood stream infections in China alone.

In April 2025, BioVersys presented outstanding Phase 2 clinical data for BV100 in Ventilator Associated Bacterial Pneumonia (VABP) at the 2025 Congress of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID Global) in Vienna, Austria. In that Phase 2, BV100 demonstrated strong signs of efficacy by halving the mortality rate in critically ill patients suffering from CRAB infections compared with best available therapy. Besides the strong efficacy signal, BV100 was also generally safe and well tolerated. In Part B of the Phase 2 trial, BV100 also proved effective in patients failing best available therapy and those suffering from totally drug-resistant infections.

Dr. Glenn E Dale, Chief Development Officer: “There is a high burden of CRAB in China and South-East Asia. As such, we are working with regulatory agencies from US, Europe and China to include patients from the three regions into a single global Phase 3 registration trial. The timely initiation of the Phase 1 safety and pharmacokinetic study in China demonstrates that the process to eventually include Chinese clinical sites into our global Phase 3 clinical program is progressing well. BioVersys is committed to bringing BV100 to patients in need in as many regions of the world as possible”

About BV100

BV100 is a novel formulation of rifabutin suitable for intravenous administration, with a recently discovered novel mode of action showing an active uptake of rifabutin into the Gram-negative bacterial species, Acinetobacter baumannii. For the first time, the BV100 allows for the targeting of the RNA-polymerase enzyme in Gram-negative bacteria with a human-suitable dose. BV100 is being developed for the treatment of infections caused by Acinetobacter baumannii calcoaceticus complex (ABC), including Carbapenem-Resistant ABC (CRAB) in critically important indications of ventilator associated bacterial pneumonia (VABP), hospital-acquired bacterial pneumonia (HABP) and bloodstream infections (BSI). BV100 was granted QIDP Designation by the U.S. FDA in May 2019 for use in the treatment of VABP, HABP and BSI, making BV100 eligible for priority FDA review, Fast Track designation, and a five-year extension of market exclusivity upon approval of the first QIDP indication.

About Acinetobacter baumannii

Acinetobacter baumannii calcoaceticus complex (ABC) are Gram-negative bacteria found in the environment (e.g., in soil and water) and an opportunistic pathogen in humans, typically infecting critically ill and immunocompromised patients, that can result in severe pneumonia and bloodstream infections in addition to affecting other parts of the body. ABC is considered a significant worldwide threat in the healthcare setting given its ability to survive for prolonged periods on surfaces, combined with its ability to develop or acquire resistance to standard of care antibiotics, e.g. carbapenems. Carbapenem-resistance as well as multidrug-resistance (MDR) rates for ABC are among the highest recorded for any bacteria in current times (The Lancet 2022; 399: 629–55). Incidence and resistance rates for ABC are trending upwards and COVID-19 has exacerbated this significantly. BioVersys forecasts the annual number of carbapenem-resistant A. baumannii infections in hospitals to have surpassed one million globally and due to the limited treatment options, such infections come with high (up to 50%) mortality rates.

About BioVersys

BioVersys AG is a multi-asset, clinical stage biopharmaceutical company focused on identifying, developing and commercializing novel antibacterial products for serious life-threatening infections caused by multi-drug resistant (“MDR”) bacteria. Derived from the company’s two internal technology platforms (TRIC and Ansamycin Chemistry), candidates are designed and developed to overcome resistance mechanisms, block virulence production and directly affect the pathogenesis of harmful bacteria towards the identification of new treatment options in the antimicrobial and microbiome fields. This enables BioVersys to address the high unmet medical need for new treatments against life-threatening resistant bacterial infections and bacteria-exacerbated chronic inflammatory microbiome disorders. The company’s most advanced research and development programs address nosocomial infections of Acinetobacter baumannii (BV100, Phase 3), and tuberculosis (alpibectir, Phase 2, in collaboration with GlaxoSmithKline (GSK) and a consortium of the University of Lille, France). BioVersys is located in the biotech hub of Basel, Switzerland.

BioVersys contact

Hernan Levett, CFO, Tel. +41 61 633 22 50; Mail: Hernan.levett@bioversys.com

For Media: media@bioversys.com

www.bioversys.com

Disclaimer

This communication expressly or implicitly contains certain forward-looking statements, such as "believe", "assume", "expect", "forecast", "project", "may", "could", "might", "will" or similar expressions concerning BioVersys and its business, including with respect to the progress, timing and completion of research, development and clinical studies for product candidates. Such statements involve certain known and unknown risks, uncertainties and other factors, which could cause the actual results, financial condition, performance or achievements of BioVersys to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. BioVersys is providing this communication as of this date and does not undertake to update any forward-looking statements contained herein as a result of new information, future events or otherwise.

^[1] J Adv Res. 2025 Jun 11:S2090-1232(25)00430-8. Burden of bacterial antimicrobial resistance in China: a systematic analysis from 1990 to 2021 and projections to 2050