BI-1808/Pembrolizumab Shows Promising Activity in Recurrent Ovarian Cancer

The combination of the novel anti-TNFR antibody BI-1808 and pembrolizumab (Keytruda) has demonstrated promising antitumor activity along with a favorable safety profile in patients with recurrent ovarian cancer, according to interim data of the phase 2a KEYNOTE-D20 trial (NCT04752826).¹

As of the data cut-off on December 18, 2025, among 17 evaluable patients with recurrent ovarian cancer, the disease control rate (DCR) was 65% (n = 11), including 4 partial responses and 7 patients with stable disease. The overall response rate (ORR) was 24%, which is higher than historical figures seen with pembrolizumab monotherapy. This enhanced efficacy was achieved with a safety profile that was generally well-tolerated by patients.

"Recurrent ovarian cancer has few options after platinum failure and a history of unsuccessful attempts to develop chemotherapy-free immunotherapy approaches," said Martin Welschof, CEO of BioInvent International, in a news release.¹ "Pembrolizumab has shown meaningful benefit only when combined with chemotherapy, while monotherapy in the KEYNOTE-100 study [NCT02674061] achieved an ORR of 8%. Against this backdrop, observing a 24% response rate and a 65% [DCR] with BI-1808 in combination with pembrolizumab is highly encouraging and has led us to expand this cohort to better qualify this signal. These results suggest that our combination could deliver a new immuno-oncology option for patients who urgently need better alternatives, and we look forward to reporting more data going forward."

About BI-1808

BI-1808 is a first-in-class IgG1 monoclonal antibody targeting TNFR2, a cell surface receptor that is notably upregulated on regulatory T cells (Tregs) within the tumor microenvironment.² TNFR2 was selected as a target due to its critical role in promoting tumor expansion and survival.

Preclinical evidence has shown that BI-1808 synergizes effectively with pembrolizumab, an anti–PD-1 immune checkpoint inhibitor. Leveraging complementary mechanisms of action, the combination represents a potential next-generation immunotherapy option that may provide clinical benefit across a range of difficult-to-treat cancers like ovarian cancer, promising to deliver antitumor responses beyond what either agent achieves alone.

Earlier this year, BI-1808 received fast track designation from the FDA for its development pathway in cutaneous T-cell lymphomas.³

About the KEYNOTE-D20 Trial

The global, multicenter, open-label phase 1/2a trial is the first-in-human clinical study of BI-1808 and is currently recruiting patients.⁴ The objective of the study is to evaluate the agent’s safety, tolerability, pharmacokinetics, and preliminary efficacy as both a single agent and in combination with pembrolizumab in patients with advanced malignancies that have progressed following standard therapy. Key efficacy end points include ORR, duration of response, and progression-free survival per RECIST v1.1 and iRECIST.

In the current phase 2a dose-expansion portion, BI-1808 is being administered via intravenous infusion at the recommended phase 2 dose determined in phase 1, either as a single agent or with 25 mg/mL of pembrolizumab.

Soon, an expansion phase will begin accruing an additional 20 patients with high-grade serous and clear cell ovarian cancer to investigate BI-1808’s activity in these subtypes. Data from this exploratory analysis is expected in the second half of 2026.

REFERENCES

1. BioInvent reports promising data from ongoing phase 2a study for BI-1808 with KEYTRUDA® (pembrolizumab) in recurrent ovarian cancer. News release. BioInvent International. January 5, 2026. Accessed January 5, 2026. https://tinyurl.com/4azvjzke

2. Rohrberg KS, Papai Z, Eefsen RL, et al. 19-BI-1808-01, a phase 1/2a clinical trial of BI-1808, a tumor necrosis factor receptor 2 (TNFR2) blocker/depleter with or without pembrolizumab. J Clin Oncol. 2024;42(16_suppl):2641-2641. doi: 10.1200/jco.2024.42.16_suppl.2641

3. BioInvent receives FDA fast track designation for BI-1808 for the treatment of cutaneous T-cell lymphoma. News release. BioInvent International. April 29, 2025. Accessed January 5, 2026. https://tinyurl.com/mr22e9rk

4. BI-1808 as a single agent and with pembrolizumab (KEYTRUDA®) in treatment of advanced malignancies (KEYNOTE-D20). ClinicalTrials.gov. Updated February 6, 2025. Accessed January 5, 2026. https://clinicaltrials.gov/study/NCT04752826