SAB Biotherapeutics (SABS) investor relations material

Phase 1 signals

• In an exploratory T1D cohort dosed at 2.5 mg/kg more than 2 years after diagnosis, all 4 patients maintained C-peptide through Day 120.

• Three of 4 patients had enhanced C-peptide; time in range rose from 73% at baseline to 85% by end of study, and insulin doses declined over time.

• Early data showed low immunogenicity, predictable PK on redosing, Treg preservation, and an increased T-cell exhaustion signature.

Mechanism and safety

• SAB-142 is a fully human, multi-specific hATG that binds CD2, CD3, CD4, and CD8 surface markers, with binding similar to rATG.

• Induction and maintenance dosing preserved Tregs and increased CD4 exhaustion markers; the presentation links exhaustion with response in prior rATG studies.

• No lymphodepletion was observed; transient lymphopenia attributed to margination returned to baseline within 5 days.

• Most adverse events were mild and associated with Day 1–2 infusions; CRS was Grade 1 only, with no serum sickness or drug-related serious adverse events.

Clinical development

• SAFEGUARD is a Phase 2b study in 159 patients aged 5–40 with new-onset Stage 3 T1D within 100 days of diagnosis; first patient was dosed in Dec 2025, with topline results expected in 2H 2027.

• SAFEGUARD evaluates induction doses of 1.5 or 2.5 mg/kg, with 1.5 mg/kg maintenance every 6 months; its primary endpoint is stimulated C-peptide at 12 months.

• PRISE is a planned Phase 3 study of 108 patients aged 5–40, spanning diagnosis windows of under 100 days, 100 days to 1 year, and 1–2 years.

• PRISE’s primary endpoint is stimulated C-peptide at 12 months; dosing includes 2.5 mg/kg induction and 1.5 mg/kg maintenance at 6 months.