ALAMEDA, Calif. — September 14, 2026
Santa Ana Bio announced that the first cohort has been dosed in the first-in-human Phase 1 clinical trial of SAB01, a novel bispecific antibody being developed for autoimmune and inflammatory diseases driven by mast cells. The company describes SAB01 as a first-in-class approach designed to selectively deplete mast cells through simultaneous engagement of KIT and Siglec-6. The clinical transition represents a major development milestone for Santa Ana Bio as it moves its precision immunology platform from preclinical research into human testing. The company aims to develop a more selective mast-cell depletion strategy while addressing safety limitations associated with broader KIT-targeted approaches. The randomized, double-blind, placebo-controlled study will initially evaluate SAB01 in healthy adults through both subcutaneous and intravenous administration.
SAB01 Targets Mast Cells Through Dual-Receptor Engagement
SAB01 is engineered to co-engage KIT and Siglec-6, two receptors expressed together on mast cells but not together on other cell types, according to Santa Ana Bio. The company’s approach uses avidity-driven binding of both receptors to concentrate activity on mast cells rather than broadly inhibiting KIT. Santa Ana Bio believes this selectivity could enable sustained mast-cell depletion while sparing other KIT-expressing cells, including hematopoietic stem cells and melanocytes. The strategy is designed to address a limitation of existing KIT therapeutics, which can produce off-target effects because KIT is not exclusive to mast cells. SAB01 also incorporates an extended half-life, with the goal of providing durable mast-cell depletion through a targeted mechanism. The company is positioning the candidate as a potential new therapeutic approach for diseases in which mast cells play a central role.
Phase 1 Study Evaluates Safety and Pharmacology
The Phase 1 trial is designed to characterize the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of SAB01 following single doses administered subcutaneously or intravenously. The study is expected to enroll 56 healthy adult participants across six subcutaneous cohorts and one intravenous cohort, with eight participants in each cohort. Participants will be randomized 6:2 to receive SAB01 or placebo in this single ascending dose study. Additional cohorts may be added to investigate selected dose levels based on emerging safety, PK and PD findings. The trial, identified as NCT07815561, will provide the first clinical assessment of whether SAB01’s selective mast-cell depletion mechanism translates from preclinical studies into measurable biological activity in humans. Results from the dose-escalation program are expected to guide subsequent clinical development and potential evaluation in patients with mast-cell-driven autoimmune and inflammatory diseases.
Advertisement
Santa Ana Bio Builds Precision Immunology Pipeline
The initiation of SAB01 clinical testing marks the first clinical-stage milestone for Santa Ana Bio’s precision immunology strategy. The company is developing targeted therapies for autoimmune and inflammatory diseases using a multi-omics platform intended to identify and address disease-driving biology. SAB01 represents an application of that strategy to mast-cell biology, combining receptor-level selectivity with a bispecific antibody design. The company’s development objective is to create therapies that can selectively modulate disease-relevant immune cells while minimizing effects on healthy cell populations. As Phase 1 progresses, Santa Ana Bio will use safety, PK and PD findings to determine the appropriate path toward patient studies. With SAB01 now in human testing, Santa Ana Bio is establishing its clinical development platform around targeted immune-cell depletion and potentially safer approaches to mast cell-driven disease.
Source: Santa Ana Bio, press release
