BI-1808 Plus Pembrolizumab Yield Antitumor Activity in Recurrent Ovarian Cancer

Interim results from the ongoing phase 2a study (NCT04752826) of BioInvent's BI-1808 in combination with pembrolizumab (Keytruda) demonstrate highly encouraging antitumor activity in patients with recurrent ovarian cancer who have progressed after platinum-based therapy.^1,2

As of December 18, 2025, interim data from the signal-seeking cohort in recurrent ovarian cancer show promising efficacy and a manageable safety profile for the BI-1808 and pembrolizumab combination.¹

The combination achieved an overall response rate (ORR) of 24%, a significant improvement over the historically observed 8% ORR for pembrolizumab monotherapy in this patient population.

The study also reported a disease control rate of 65%, with several patients experiencing durable stable disease beyond 8 months. These results are particularly noteworthy given the significant unmet medical need in recurrent ovarian cancer, where treatment options are limited, and previous attempts to develop chemotherapy-free immunotherapies have been largely unsuccessful.

Some responses were observed after several months of treatment, suggesting that additional responses may emerge over time, potentially impacting progression-free survival.

Exploratory analyses indicate strong activity in both high-grade serous and clear cell ovarian cancer subtypes.

The combination of BI-1808 and pembrolizumab was reported to be generally safe and well-tolerated. All adverse events were manageable with standard medical treatments.

Addressing a High Unmet Need

Treatment for recurrent ovarian cancer remains a significant challenge in oncology, characterized by:

• Limited treatment options available after failure of platinum-based therapy.
• A history of low response rates to immunotherapies when used without chemotherapy.

"Recurrent ovarian cancer has few options after platinum failure and a history of unsuccessful attempts to develop chemotherapy-free immunotherapy approaches,” stated Martin Welschof, CEO of BioInvent, in a news release. “These results suggest that our combination could deliver a new immuno-oncology option for patients who urgently need better alternatives."

Study Rationale

The decision to evaluate this combination in ovarian cancer was supported by strong pre-clinical and early clinical evidence.

Preclinical studies demonstrated that combining BI-1808 with pembrolizumab resulted in synergistic antitumor activity.

Notably, a complete response was previously observed in a platinum-resistant ovarian cancer patient treated with BI-1808 as a single agent, highlighting the drug's potential in this specific population.

Mechanism of Action of BI-1808

BI-1808 is a novel, first-in-class immuno-modulatory antibody designed to enhance antitumor immune responses.

BI-1808 targets tumor necrosis factor receptor 2 (TNFR2), which is highly expressed on tumor-associated regulatory T cells (Tregs) within the tumor microenvironment. TNFR2 is critical for the survival and expansion of these immunosuppressive cells.

BI-1808 is a ligand-blocking, FcgR-engaging antibody that works through a dual mechanism:

1. It depletes the immunosuppressive Tregs.
2. It reprograms myeloid cells. The combined effect triggers potent CD8+ T cell-mediated antitumor immunity.

Next Steps

Based on the encouraging interim results, BioInvent will expand the ovarian cancer cohort to an additional 20 patients. The expansion will focus on validating the signal in high-grade serous and clear cell ovarian cancer subtypes. A data readout from the expanded cohort 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. Published January 5, 2026. Accessed January 30, 2026. https://tinyurl.com/3j9vw28p

2.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 30, 2026. https://clinicaltrials.gov/study/NCT04752826