Lund, Sweden – April 21, 2026 – BioInvent International AB (“BioInvent”) (Nasdaq Stockholm: BINV), a leader in the discovery of novel immune-modulatory antibodies, today announced that additional clinical data from its ongoing Phase 2a study evaluating BI-1808 in combination with MSD’s (Merck & Co., Inc., Rahway, NJ., USA) anti-PD-1 therapy, KEYTRUDA^® (pembrolizumab), in advanced ovarian cancer has been selected for a poster presentation at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting taking place in Chicago May 29 – June 2, 2026.

• Title: BI-1808 + Pembrolizumab: A Chemotherapy-Free Regimen Shows Promising Responses in Advanced Ovarian Cancer
• Presenter: Dr. Anja Williams, Sarah Cannon Research Institute, United Kingdom
• Date and Time: May 30, 2026, 1:30 pm - 4:30 pm CDT
• Additional details: Session Developmental Therapeutics – Immunotherapy. Annual Meeting abstracts will go public at 5:00 PM (EDT) on Thursday, May 21, 2026.

The presentation will highlight findings from the ovarian cancer cohort in the ongoing Phase 2a trial (NCT04752826), evaluating the antitumoral activity of BI-1808 in combination with pembrolizumab in heavily pretreated, recurrent ovarian cancer.

As disclosed in February 2026, 21 patients with recurrent ovarian cancer treated with the combination had been evaluated. The results indicated an overall response rate of 24% and a disease control rate (DCR) of 57%; 5 partial responses (PR), 7 patients with stable disease (SD), with several durable SD beyond 10 months and ongoing. Some responses were observed after several months of treatment, suggesting that additional responses with potentially important impact on PFS (Progression Free Survival) may be observed. The combination was generally safe and well tolerated, and all adverse events were manageable with standard medical treatments. Exploratory analyses indicate strong activity in both high-grade serous and clear cell ovarian cancer subtypes.

As disclosed earlier, BI-1808 monotherapy data shows one complete response (CR), 1 PR and 9 patients with SD (out of 26 evaluable solid tumor patients). Data was presented at ASCO 2024. The patient with PR is doing well and has completed study treatment. This patient continues the treatment outside of the study (per patient treatment).

Clinical trial collaboration and supply agreement
KEYTRUDA^® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. BioInvent has a clinical trial collaboration and supply agreement with MSD, a tradename of Merck & Co., Inc., Rahway, NJ., USA, to evaluate the combination of BI-1808 and MSD’s anti-PD-1 therapy, KEYTRUDA^® (pembrolizumab). 

About the Phase 2a Study
This Phase 2a trial (NCT04752826) is designed to assess BI-1808 administered as a single agent (Part A) and in combination with pembrolizumab (Part B). The aim of the Phase 2a is to further assess the safety and tolerability of BI-1808 as a single agent (Part A) and in combination with pembrolizumab (Part B), characterize its PK and pharmacodynamics, and assess preliminary antitumor activity by ORR, DoR (duration of response), and progression-free survival (PFS), as measured by RECIST v1.1 and iRECIST.

About BI-1808
The anti-TNFR2 antibody BI-1808 is part of BioInvent’s tumor-associated regulatory T cells (Treg)-targeting program. TNFR2 is particularly upregulated on Tregs of the tumor microenvironment and has been shown to be important for tumor expansion and survival, representing a new and promising target for cancer immunotherapy. BI-1808 is a first-in-class drug candidate in clinical development for the treatment of T-cell lymphoma and solid tumors.

A manuscript detailing the mechanisms of action of the BI-1808 and differentiated BI-1910 anti-TNFR2 antibodies is available on BioRxiv.com, an open-access online repository for yet unpublished research manuscripts (preprints). Both anti-TNFR2 antibodies show potent anti-tumor efficacy across multiple syngeneic mouse tumor models, can effectively be combined with anti-PD-1, and trigger CD8+ T cell antitumor immunity, albeit by different mechanisms; BI-1808 is a ligand-blocking FcgR-engaging antibody that depletes immunosuppressive Treg cells and reprograms myeloid cells. BI-1910 is a pure agonist antibody that directly co-stimulates T and NK cells through partially FcgR-independent mechanisms.

About BioInvent
BioInvent International AB (Nasdaq Stockholm: BINV) is a clinical-stage biotech company that discovers and develops novel and first-in-class immuno-modulatory antibodies for cancer therapy, with drug candidates in ongoing clinical programs in Phase 1/2 trials for the treatment of hematological cancer and solid tumors. The Company's validated, proprietary F.I.R.S.T™ technology platform identifies both targets and the antibodies that bind to them, generating many promising new immune-modulatory candidates to fuel the Company's own clinical development pipeline and providing licensing and partnering opportunities.

The Company generates revenues from research collaborations and license agreements with multiple top-tier pharmaceutical companies, as well as from producing antibodies for third parties in the Company's fully integrated manufacturing unit. More information is available at www.bioinvent.com.

For further information, please contact:
Cecilia Hofvander, VP Investor Relations
Phone: +46 (0)46 286 85 50
Email: cecilia.hofvander@bioinvent.com

BioInvent International AB (publ)
Co. Reg. No.: 556537-7263
Visiting address: Ideongatan 1
Mailing address: 223 70 LUND
Phone: +46 (0)46 286 85 50
www.bioinvent.com

The press release contains statements about the future, consisting of subjective assumptions and forecasts for future scenarios. Predictions for the future only apply as the date they are made and are, by their very nature, in the same way as research and development work in the biotech segment, associated with risk and uncertainty. With this in mind, the actual outcome may deviate significantly from the scenarios described in this press release.