BioInvent International AB has announced that the US Food and Drug Administration (FDA) has granted Fast Track Designation to BI-1808, the company’s first-in-class anti-TNFR2 antibody, for the treatment of ovarian cancer in combination with pembrolizumab.

The designation is intended to facilitate the development and regulatory review of BI-1808 for patients with ovarian cancer, an area where significant unmet medical needs remain, particularly among patients whose disease has progressed following platinum-based therapy.

Martin Welschof, Chief Executive Officer of BioInvent, said the FDA designation represents an important milestone for BI-1808 and reflects both the unmet need in difficult-to-treat ovarian cancer and the clinical signals generated so far. He noted that data across high-grade serous and clear cell ovarian cancer subtypes support the potential of TNFR2 targeting to enhance the activity of PD-1 inhibitors in tumours where these therapies have historically delivered limited benefit.

BI-1808 is designed to target tumour necrosis factor receptor 2 (TNFR2), which is highly expressed on immunosuppressive regulatory T cells (Tregs) within the tumour microenvironment. The antibody is intended to deplete these Tregs while activating myeloid cells and CD8-positive T cells, potentially enhancing anti-tumour immune responses and creating synergy with PD-1 blockade.

The company said interim Phase 2a data presented at the ASCO 2026 Congress demonstrated encouraging activity for BI-1808 in combination with pembrolizumab without chemotherapy. In heavily pretreated patients with recurrent ovarian cancer following platinum therapy, the combination achieved a 24 percent confirmed Overall Response Rate (ORR) and a 56percent Disease Control Rate (DCR).

Responses were observed across both high-grade serous and clear cell ovarian cancer subtypes. Several patients experienced prolonged disease control, with some responses continuing beyond 10 months. Preliminary analyses indicated a median Progression-Free Survival (mPFS) of 10.3 months.

The results are notable given the limited activity historically observed with pembrolizumab monotherapy in this patient population, where the company cited an approximately 8 percent response rate.

The ongoing Phase 2a study, registered as NCT04752826, is evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary anti-tumour activity of BI-1808 across multiple treatment settings. Part A evaluates BI-1808 as a monotherapy, Part B assesses the combination with pembrolizumab, while Part C evaluates a triple combination of BI-1808, pembrolizumab and paclitaxel.

The study is assessing treatment outcomes through measures including overall response rate, duration of response and progression-free survival, using RECIST v1.1 and iRECIST criteria.

BioInvent has been collaborating with MSD, known as Merck & Co in the United States and Canada, since August 2021 under a clinical trial collaboration and supply agreement to evaluate BI-1808 in combination with the company’s anti-PD-1 therapy, Keytruda (pembrolizumab).

BI-1808 forms part of BioInvent’s tumour-associated Treg-targeting programme. TNFR2 is considered an important target in cancer immunotherapy because of its elevated expression on Tregs in the tumour microenvironment and its role in supporting tumour expansion and survival.

The investigational antibody is being evaluated in clinical development for both T-cell lymphomas and solid tumours. BioInvent said BI-1808 has demonstrated single-agent activity and favourable tolerability in an ongoing Phase 2a study, while combination studies with pembrolizumab have generated efficacy and safety signals across solid tumours and T-cell lymphomas.

Preclinical research has further supported the mechanism of BI-1808. The antibody is designed as a ligand-blocking, Fc-gamma receptor-engaging therapy that can deplete immunosuppressive Tregs and reprogramme myeloid cells. In preclinical tumour models, BI-1808 demonstrated anti-tumour activity and enhanced responses when combined with anti-PD-1 therapy, with increased CD8-positive T-cell-mediated anti-tumour immunity.

BioInvent is a clinical-stage biotechnology company focused on discovering and developing novel immunomodulatory antibodies for cancer treatment. Its pipeline includes first-in-class drug candidates being evaluated in Phase 1/2 clinical programmes for haematological cancers and solid tumours.