Janux Therapeutics (JANX) Study update summary

Phase 1 study design and findings

• Initial data: 25 healthy volunteers across five single-ascending-dose cohorts (30 μg–3 mg SC), without step-up dosing; data cutoff Nov. 2, 2026.

• At 3 mg, 3/5 participants achieved >90% peripheral B-cell depletion, including two with counts below detection; dose-dependent reductions persisted through Day 42.

Safety and pharmacology

• CRS rates were 0/16 at 30–300 μg, 1/4 at 1 mg and 4/5 at 3 mg; all events were Grade 1 and resolved with acetaminophen.

• No serious adverse events or dose-limiting toxicities; other treatment-related events were predominantly Grade 1. Transient, asymptomatic Grade 3 ALT and Grade 2 ALT/AST elevations occurred at 3 mg.

• Limited inflammatory cytokine increases were observed, consistent with the Grade 1-only CRS profile.

ARM mechanism and platform rationale

• JANX011 is a CD19-targeted bispecific T-cell engager designed to recruit T cells through the conserved TRBV6 domain rather than CD3; TRBV6-positive cells comprise ~10% of T cells.

• Dose-responsive activation occurred in TRBV6-positive CD4 and CD8 cells, with limited activation in TRBV6-negative cells; findings link selective activation with deep B-cell depletion and Grade 1-only CRS.

• The ARM platform may extend to additional B-cell targets, autoimmune indications and heme-oncology applications.