BI-1808 Receives FDA Fast Track Designation in Ovarian Cancer

The FDA has granted fast track designation to BI-1808, a first-in-class anti-TNFR2 antibody, for the treatment of advanced platinum-resistant ovarian cancer in combination with pembrolizumab (Keytruda), according to a news release from BioInvent International AB.¹

The designation follows interim phase 2a trial (NCT04752826) results presented in a poster at the 2026 ASCO Annual Meeting, in which BI-1808 plus pembrolizumab, without chemotherapy, yielded a confirmed objective response rate (ORR) of 24% and a disease control rate (DCR) of 56% in heavily pretreated patients with advanced platinum-resistant ovarian cancer.² Durable benefit was observed across both high-grade serous and clear cell histologic subtypes, with several responses ongoing beyond 10 months and prolonged stable disease reported in multiple patients. Preliminary analyses indicated a median progression-free survival (PFS) of 10.3 months, according to the release.

“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,” Martin Welschof, PhD, chief executive officer of BioInvent, stated in the news release.¹

Mechanism and Study Design

BI-1808 targets TNFR2, a receptor upregulated on regulatory T cells (Tregs) within the tumor microenvironment that has been implicated in tumor expansion and survival. According to the company, BI-1808 depletes immunosuppressive Tregs, activates myeloid cells and CD8-positive T cells in the tumor microenvironment, and synergizes with PD-1 inhibition.

The ongoing phase 2a trial is evaluating BI-1808 as a single agent (part A), in combination with pembrolizumab (part B), and in a triplet with pembrolizumab and paclitaxel (part C). 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. Cohort expansion focusing on the high-grade serous and clear cell subtypes is underway, with an additional data readout expected in the second half of 2026.

Efficacy in Context: Monotherapy vs Combination

In the monotherapy cohort (part A; n = 17 patients, predominantly high-grade serous adenocarcinoma), BI-1808 alone showed limited single-agent activity, with a 41% DCR (1 complete response, 6 with stable disease) and a median PFS of 3.6 months, according to the poster. By comparison, pembrolizumab monotherapy in the KEYNOTE-100 trial (NCT02674061) achieved an ORR of 8% and a median PFS of 2.1 months in ovarian cancer, a historical benchmark the investigators cited as context for BI-1808's modest single-agent effect.²

In the combination cohort (part B; n = 26 patients, including 17 with high-grade serous adenocarcinoma and 9 with clear cell ovarian carcinoma), BI-1808 plus pembrolizumab resulted in a confirmed ORR of 24% (1 complete response, 5 partial responses) and a DCR of 56%, with 8 additional patients achieving stable disease, several lasting more than 10 months. Responses were observed across both high-grade serous and clear cell subtypes.

The investigators noted that historical pembrolizumab data in ovarian cancer indicate a median time to response of 9 to 12 weeks, whereas interpolation of preclinical data predicted a longer time to response for BI-1808 of 19 to 25 weeks as monotherapy and 13 to 17 weeks in combination with pembrolizumab. According to the poster, 86% of progressive disease exclusions occurred within 13 weeks, which the investigators said could potentially be too early to detect responses and could mean pseudoprogression is misinterpreted as true tumor progression.

Disease Background and Development Context

Patients with recurrent ovarian cancer who progress after platinum-based therapy face substantial unmet need; pembrolizumab monotherapy in this setting has historically achieved a response rate of only 8%. BI-1808 is also in clinical development for T-cell lymphoma and other solid tumors, and the company has reported single-agent activity and tolerability in an ongoing phase 2a study, along with efficacy and a favorable safety profile in combination with pembrolizumab in an ongoing phase 1/2a study spanning solid tumors and T-cell lymphomas.¹

REFERENCES

1. 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 7, 2026.

2. Kristelleit R, Williams A, Lopez J, et al. BI-1808 + pembrolizumab: responses to a chemotherapy-free regimen in advanced ovarian cancer. J Clin Oncol. 2026;44(suppl 16):2605. doi:10.1200/JCO.2026.44.16_suppl.2605