Shattuck Labs, Inc. 8-K

What Happened

• Shattuck Labs (STTK) announced results from its first-in-human Phase 1 trial of SL-325 (a DR3‑blocking antibody) and disclosed upcoming development milestones. The company said the Phase 1 study (72 participants across single- and multiple-ascending dose cohorts) showed complete DR3 receptor occupancy at doses ≥0.1 mg/kg, durable TL1A blockade for >10 weeks, a favorable safety profile, and low immunogenicity. Shattuck expects to initiate the RECEPTIVE‑CD1 Phase 2b trial in Crohn’s disease in Q3 2026 and plans to file an IND for its bispecific SL-846 in the first half of 2027.

Key Details

• Phase 1 enrolled 72 participants; ADA (antidrug antibodies) detected in 3.7% (2/54) of treated participants, low titer (≤16) with no impact on PK or receptor occupancy.
• Complete DR3 occupancy (blockade of TL1A binding) observed at doses ≥0.1 mg/kg and durable >10 weeks; modeling suggests >3 months of full TL1A inhibition at doses >1 mg/kg.
• Safety: no serious treatment-emergent adverse events; all treatment‑related adverse events were Grade 1 (observed in 12 participants).
• RECEPTIVE‑CD1 Phase 2b: ~174 patients randomized 1:1:1 (low dose / high dose / placebo); 12‑week induction + 40‑week maintenance; primary endpoint endoscopic response at Week 12 (topline expected H1 2028).
• SL-846 (DR3xIL‑23R bispecific): GLP tox data expected H2 2026; IND planned H1 2027.

Why It Matters

• For investors, the Phase 1 data support a favorable safety, durability, and low-immunogenicity profile for SL-325, which could enable less-frequent dosing (quarterly) and a stronger clinical profile versus some competitors.
• Upcoming catalysts include starting the Phase 2b Crohn’s study in Q3 2026 and an IND for SL-846 in H1 2027; these are near‑term development milestones that could drive program value if results are positive.
• The company’s clear timelines and concrete Phase 1 metrics (occupancy, ADA rate, safety) give measurable expectations for monitoring progress through 2026–2028.