ISA Pharmaceuticals B.V., a clinical-stage biotech company developing immunotherapies to treat cancers and serious infectious diseases, is pleased to announce that the first patient has been dosed in the HEB-PEP study. This first-in-human (FIH) phase 1 study investigates the use of ISA104, a novel treatment aimed to establish functional cure in Chronic Hepatitis B patients. Dosing took place at the Liver Unit of the Erasmus Medical Center in Rotterdam, the sponsor of this dose escalation study.

The HEB-PEP study will investigate the safety, tolerability and efficacy of different doses of ISA104 in chronic HBV patients versus placebo. Details of the study can be found at clinicaltrials.gov under identifier NCT05841095. The study is conducted in collaboration with investigators of the Gastroenterology & Hepatology department of the Erasmus MC in Rotterdam, The Netherlands and is co-funded by a PPP Allowance made available by Health~Holland, Top Sector Life Sciences & Health, to stimulate public-private partnerships.

Hepatitis B is a serious liver infection and a global health threat caused by the development of chronic infection in a proportion of patients who are unable to clear the virus and become carriers. It increases a person's risk of developing liver cancer, liver failure, and/or cirrhosis for which no effective curative treatments are available. Two billion people around the world have been infected with the hepatitis B virus, with approximately 1.5 million people becoming newly infected each year. Approximately 300 million people are suffering from the chronic sequelae of this disease.

In collaboration with Erasmus MC and using ISA's Synthetic Long Peptide (SLP®) technology, ISA has developed ISA104 immunotherapy. ISA104 is designed to create a strong and specific immune response against HBV, with the aim to functionally cure chronically infected patients. ISA has previously demonstrated the effectiveness of SLP immunotherapy in patients that were chronically infected with human papillomavirus type 16 (HPV16).

Leon Hooftman, Chief Medical Officer of ISA Pharmaceuticals said: "We are delighted to announce that the first patient has been enrolled with ISA104 in the HEB-PEP clinical study, marking an important milestone in our mission to develop an effective treatment for patients with chronic hepatitis B virus infection, a tremendous global health burden and a defined cause of liver cancer. The study will provide crucial information on the safety and potential efficacy of ISA104, as we continue to advance our clinical programs with a focus on improving patient outcomes."

Dr. Sonja Buschow and Dr. Dave Sprengers, Principal Investigators of the study from Erasmus MC's Department of Gastroenterology & Hepatology, commented: "We are excited by the progress we are making in this first in human trial and eager to learn the potential impact that ISA104 based therapy could have on patients suffering from chronic hepatitis B virus infection. This study will allow us to determine how safety issues and immune responses in patients receiving ISA104 relate to those occurring by chance and to deepen our understanding of this promising new therapy, of HBV-directed immune responses and on novel HBV biomarkers"

ISA104 is ISA's latest pipeline program to enter clinical development, following its lead program ISA101b which is in late-stage clinical development for the treatment of HPV16-induced cancers.