Science & Platform
Engineering precision at the molecular level
Our single-domain antibody platform enables a new class of multivalent and multispecific biologics — molecules that conventional antibody formats simply cannot build.
The sdAb Platform
Single-domain antibodies. Unlimited architecture.
Conventional monoclonal antibodies are large, bivalent molecules constrained by their Y-shaped structure. Single-domain antibodies (sdAbs) — also called nanobodies — are the smallest functional antibody fragments found in nature, derived from the heavy-chain-only antibodies of camelids.
At roughly one-tenth the size of a conventional antibody, sdAbs can be combined like modular building blocks into multivalent and multispecific formats with precise control over valency, geometry, and target engagement. This is the architectural freedom that defines our platform.
Size comparison
Platform advantages
Why sdAbs unlock biology that IgGs cannot
Multivalency by design
Multiple sdAb units can be linked in a single molecule, enabling avidity effects and receptor clustering that drive potent agonism — a capability uniquely suited to targets like OX40, DR5, and TRAIL receptors.
Multispecificity without compromise
Unlike bispecific antibodies that sacrifice one binding arm, sdAb-based multispecifics can engage three, four, or more targets simultaneously — enabling tumor microenvironment redirection and co-stimulatory pathway activation.
Tissue penetration
The compact size of sdAbs enables superior tissue penetration compared to full-sized antibodies, potentially improving access to solid tumor microenvironments and dense tissue compartments.
Stability and manufacturability
sdAbs are thermostable, resistant to aggregation, and highly amenable to recombinant expression — supporting robust, scalable manufacturing processes for clinical and commercial supply.
Half-life engineering
By incorporating albumin-binding sdAbs or Fc fusions, we can tune serum half-life across a wide range — from hours to weeks — matching the pharmacokinetic profile to the therapeutic indication.
Reduced immunogenicity risk
Humanized sdAb frameworks combined with our engineering expertise minimize the risk of anti-drug antibody responses, supporting chronic dosing regimens in oncology and rare disease.
Mechanism of Action
Targeting the biology others cannot reach
Our programs are designed to engage receptor systems where multivalency is not just beneficial — it is mechanistically required. Agonistic receptors in the TNF superfamily, for example, require receptor clustering to initiate signaling. Our hexavalent and trivalent sdAb formats are purpose-built for this biology.
Receptor clustering
Multivalent sdAb formats crosslink receptor complexes on the cell surface, driving agonistic signaling that monovalent antibodies cannot achieve.
Tumor microenvironment targeting
Multispecific formats redirect immune effector cells to the tumor site while simultaneously activating co-stimulatory pathways — combining targeting with immune activation.
Apoptosis induction
Programs targeting DR5 and TRAIL receptors leverage receptor clustering to activate the extrinsic apoptosis pathway selectively in tumor cells.
Rare disease correction
In alpha-1 antitrypsin deficiency, our approach targets the underlying protein misfolding and polymerization — addressing the root cause rather than downstream consequences.
From Platform to Pipeline
Five programs. One platform.
Every program in our pipeline is a direct expression of our sdAb platform — each designed to engage biology that conventional antibodies cannot address.
| Program | Target | Modality | Indication |
|---|---|---|---|
| INBRX-109 | DR5 | Tetravalent sdAb | Chondrosarcoma |
| INBRX-106 | OX40 | Hexavalent sdAb | Solid tumors |
| INBRX-105 | PD-L1 × 4-1BB | Bispecific sdAb | Solid tumors |
| INBRX-101 | AAT | Recombinant fusion | AATD |
| INBRX-112 | CD38 | sdAb-based | Multiple myeloma |
Publications
Science in the literature
Multivalent single-domain antibodies as agonists of the DR5 death receptor pathway in solid tumors
Hexavalent OX40 agonism via sdAb engineering drives superior T cell co-stimulation in preclinical models
Single-domain antibody platform enables precise multispecific biologic design for oncology
Ready to see the pipeline?
Explore our clinical programs built on the sdAb platform.