BI-1808 Earns FDA Fast Track Status for Advanced Ovarian Cancer

The FDA has granted fast track designation to BI-1808, a first-in-class anti-TNFR2 antibody, for the treatment of ovarian cancer in combination with pembrolizumab (Keytruda), according to a news release from the developer, BioInvent International AB.¹ The designation is based on interim phase 2a data (NCT04752826) presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, in which the chemotherapy-free combination produced responses in heavily pretreated patients with platinum-resistant ovarian cancer (PROC).²

“Receiving FDA Fast Track Designation for BI-1808 in ovarian cancer is an important milestone that reflects the significant unmet medical need in this difficult-to-treat disease and the strength of the clinical signals we have generated to date,” stated Martin Welschof, chief executive officer of BioInvent, in the press release.¹ “The data we have presented across both high-grade serous and clear cell subtypes underscore the potential of targeting TNFR2 to meaningfully enhance the activity of PD-1 inhibitors in tumors where these agents have historically shown limited benefit. This designation validates our development strategy and strengthens our commitment to advancing BI-1808 as a new treatment option for patients with ovarian cancer.”

What were the key efficacy findings for BI-1808 plus pembrolizumab?

Among 26 patients with recurrent ovarian cancer treated with BI-1808 plus pembrolizumab in part B of the phase 2a trial, the combination produced a confirmed objective response rate (ORR) of 24% and a disease control rate (DCR) of 56%. Responses included 1 complete response (CR) and 5 partial responses (PR), plus 8 patients with stable disease (SD), several of which lasted more than 10 months. The cohort comprised predominantly high-grade serous adenocarcinoma (n = 17/26), with the remainder representing clear-cell ovarian carcinoma; responses were observed across both histologic subtypes.

Preliminary analysis indicated a median progression-free survival (PFS) of 10.3 months, which was still maturing as 9 of the responding patients remained on treatment at the April 20, 2026, data cutoff. By comparison, prior data from the phase 2 KEYNOTE-100 trial (NCT02674061) showed pembrolizumab monotherapy produced an ORR of 8% and a median PFS of 2.1 months in ovarian cancer. In part A of this trial, single-agent BI-1808 exhibited similarly limited activity, with 1 CR and a median PFS of 3.6 months among 17 patients.

The combination was overall well tolerated, with low rates of grade 3 or higher adverse effects (AEs) and treatment-related discontinuations occurring in less than 5% of the combination arm.

The most common any grade treatment-emergent AEs were fatigue (27%), pyrexia (23%), hypothyroidism (16.2%), hyperthyroidism (14.9%), and diarrhea (10.8%).

What is BI-1808 and how does it work?

BI-1808 is a first-in-class IgG1 monoclonal antibody that targets TNFR2, a receptor upregulated on regulatory T cells (Tregs) within the tumor microenvironment. The antibody blocks TNF-α binding and, through Fcγ receptor engagement, depletes Tregs and reprograms myeloid cells, which in turn expands antitumor CD8-positive T cells.

Translational data from the trial showed that BI-1808 reduced Treg levels and, in combination with pembrolizumab, increased levels of activated CD8-positive T cells. The combination also increased cytokines associated with the formation of tertiary lymphoid structures, which support antitumor T-cell responses.

What is the design of the ongoing phase 2a trial?

The phase 2a trial is evaluating BI-1808 as a single agent (part A), in combination with pembrolizumab (part B), and in a triplet combination with pembrolizumab and paclitaxel (part C) in patients with recurrent ovarian cancer previously treated with at least 1 platinum-containing regimen.

In the interim analysis, patients received BI-1808 at 1000 mg with or without pembrolizumab at 200 mg every 3 weeks for up to 2 years.

The study is designed to characterize safety, pharmacokinetics, and pharmacodynamics, and to assess preliminary antitumor activity by ORR, duration of response, and PFS per RECIST v1.1 and iRECIST criteria. The trial aims to enroll 20 patients in the monotherapy cohort and 40 in the combination cohort; at the April 2026 data cutoff, 12 patients in the combination cohort were still awaiting first assessment, and cohort expansion is ongoing with a focus on high-grade serous and clear cell subtypes.

References

1. BioInvent International AB. BioInvent receives FDA fast track designation for BI-1808 for the treatment of ovarian cancer. News release. BioInvent International AB. August 7, 2026. Accessed August 10, 2026. https://tinyurl.com/5bcn8p85
2. Kristelleit R, Williams A, Lopez J, et al. BI-1808 + pembrolizumab: responses to a chemotherapy-free regimen in advanced ovarian cancer. Presented at: 2026 ASCO Annual Meeting; May 29-June 2, 2026; Chicago, IL. Abstract 2605.