BioInvent to present BI-1808 data in platinum-resistant recurrent ovarian cancer at ESMO 2026

• The abstract was published today on the ESMO website. It repeats data presented at ASCO 2026 (25 evaluable patients, cutoff May 6, 2026) 
• Objective response rate was 24% (6 of 25 evaluable patients): 1 complete response and 5 partial responses with durable disease control
• Preliminary median progression-free survival (PFS) according to RECIST was 4.2 months. Median PFS per iRECIST (miPFS), a criterion designed to capture delayed responses, was 10.3 months 
• Fewer than 5% treatment-related discontinuations
• Poster (#2009P) will be presented on October 24 at 12:00–12:45 CEST and will include updated data from a larger number of patients.

Lund, Sweden – October 19, 2026 – BioInvent International AB (“BioInvent”) (Nasdaq Stockholm: BINV), a leader in the discovery of novel immunomodulatory antibodies, today announced the publication of an abstract ahead of its poster presentation at the ESMO Congress 2026 (European Society for Medical Oncology) in Madrid, October 23–27. The abstract reports previously communicated Phase 1/2a data (ASCO 2026) for BI-1808, a first-in-class anti-TNFR2 antibody, combined with MSD's (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 therapy KEYTRUDA® (pembrolizumab) in patients with heavily pretreated platinum-resistant ovarian cancer.

Patients with platinum-resistant recurrent ovarian cancer (PRROC) have limited treatment options after relapsing, with approximately 70% of patients experiencing recurrence after platinum-based chemotherapy.³ While PD-1 blockade has demonstrated only modest activity as monotherapy in this setting, BI-1808 enhances anti-tumor immunity through a differentiated mechanism targeting TNFR2, which regulates immunosuppressive Tregs and drives immune suppression of myeloid cells in the tumor microenvironment.

Abstract summary
As of May 6, 2026, in the first 25 evaluable patients who reached initial response assessment, the treatment achieved:

• 24% objective response rate (ORR), including 1 complete response (CR) and 5 partial responses (PRs)
• Responses across both high-grade serous adenocarcinoma (HGSA) and clear cell ovarian cancer subtypes
• Preliminary median progression-free survival (mPFS) was 4.2 months per RECIST 1.1 and 10.3 months per iRECIST (miPFS). iRECIST is designed to capture delayed responses.
• Fewer than 5% treatment-related discontinuations
• Biomarker evidence of significant Treg depletion and robust CD8+ T-cell activation
  

These findings further support BI-1808's mechanism of action (Mårtensson, et al (Cancer Research https://doi.org/10.1158/0008-5472.CAN-26-0274), which combines TNF-α/TNFR2 pathway blockade with Fcγ receptor-mediated depletion of immunosuppressive Tregs and activation of the myeloid component of the TME (tumor microenvironment), thereby promoting expansion, activation and tumor infiltration by anti-tumor CD8+ T cells. Enrollment to the combination cohort (BI-1808 plus pembrolizumab) has been completed.

Poster presentation details
Title: From Modest to Meaningful: Targeting TNFR2 with BI-1808 to Unlock Checkpoint Inhibitor Efficacy in Platinum-Resistant Recurrent Ovarian Cancer (PRROC)
Session: Investigational immunotherapy, presentation number 2009P
Date/time: October 24, at 12:00–12:45 CEST

RECIST versus iRECIST
iRECIST is an immunotherapy-adapted response criteria developed to assess late responses unique to immune-based cancer treatments. In addition to using iRECIST, the conventional RECIST assessment has also been evaluated in the BI-1808 clinical program. Response assessments using both RECIST and iRECIST are prospectively studied in the program.

Under traditional RECIST v1.1 criteria, progression is recorded when new lesions appear or tumors initially increase in size. However, immunotherapies can sometimes produce pseudoprogression, a phenomenon in which immune-cell infiltration causes an initial increase in tumor size before subsequent tumor shrinkage. In these cases, RECIST may classify patients as progressing earlier than their clinical benefit suggests.

iRECIST requires confirmation of progression before treatment discontinuation and can therefore capture delayed responses and prolonged disease control that are characteristic of effective immunotherapies. As a result, median PFS measured using iRECIST may be longer than that measured using RECIST and has been proposed as a better predictor of overall survival (OS). In the BI-1808 plus pembrolizumab study, the preliminary iRECIST-based median progression-free survival was 10.3 months, and 4.2 months under conventional RECIST criteria, highlighting the potential for durable clinical benefit beyond initial radiographic changes.

Preclinical data support expansion into triplet therapy
In parallel, new preclinical studies demonstrate that BI-1808 combines effectively with paclitaxel, both alone and in combination with anti-PD-1 therapy. The addition of BI-1808 increases intratumoral immune activation and significantly improves survival in experimental models compared with paclitaxel with or without anti-PD-1 therapy. These findings are particularly relevant in light of the recently established role of paclitaxel-containing regimens in ovarian cancer and support further combination development.

Next steps
Based on encouraging efficacy, a favorable safety profile and supportive translational data, BioInvent plans to initiate Part C of the study evaluating a randomized triplet combination of BI-1808, pembrolizumab, and weekly paclitaxel (+/- bevacizumab) in patients with platinum-resistant ovarian cancer. The study is expected to start in Q1 2027 with first data expected in H2 2027, subject to enrollment.

About the BI-1808 Phase 1/2a study
This open-label Phase 1/2a study (NCT04752826, KEYNOTE-D20) is designed to assess the safety and tolerability of BI-1808 as a single agent (Part A), in combination with pembrolizumab (Part B) and in combination with pembrolizumab, paclitaxel +/- bevacizumab (Part C). The study aims to characterize safety, pharmacokinetics 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.

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. Since August 2021, 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 Ovarian Cancer
Ovarian cancer (OC) is a serious and life-threatening disease, affecting more than 320,000 women worldwide each year.¹ OC is frequently diagnosed at an advanced stage because its symptoms are often difficult to recognize. It is currently the eighth most common cancer and the eighth leading cause of cancer-related death among women globally.² Recurrence remains a major clinical challenge, affecting approximately 70% of patients after initial treatment.³ Consequently, survival outcomes remain poor, with five-year survival rates typically estimated at 30-50% across different regions.^4,5

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 solid tumors and T-cell lymphoma. BI-1808 has shown single-agent activity and excellent tolerability in the ongoing Phase 1/2a study, and efficacy and a favorable safety profile in combination with pembrolizumab for the treatment of solid tumors and T-cell lymphomas.

BI-1808 has received FDA Fast Track Designation for the treatment of ovarian cancer and for relapsed or refractory mycosis fungoides and Sézary syndrome, FDA Orphan Drug Designation for T-cell lymphoma, and Orphan Drug Designation in cutaneous T-cell lymphoma from the European Medicines Agency.

About BioInvent
BioInvent International AB (Nasdaq Stockholm: BINV) is a clinical-stage biotech company that discovers and develops novel and first-in-class immunomodulatory antibodies for cancer therapy, with drug candidates in ongoing clinical programs in Phase 1/2 trials for the treatment of solid tumors and hematological cancer. 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 immunomodulatory 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 on the Company’s website.

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.

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¹World Cancer Research Fund International. https://www.wcrf.org/cancer-trends/ovarian-cancer-statistics/
²World Ovarian Cancer Coalition. https://worldovariancancercoalition.org/about-ovarian-cancer/key-stats/
³ Ovarian Cancer Research Alliance. https://ocrahope.org/patients/diagnosis-and-treatment/recurrence/
⁴ European Institute of Women's Health. https://eurohealth.ie/policy‐brief‐women‐and‐ovarian‐cancer‐in‐the‐eu‐2018/.
⁵ American Cancer Society. Stages of Ovarian Cancer. https://www.cancer.org/cancer/types/ovarian-cancer/detection-diagnosis-staging/survival-rates.html.