The B-Body^® Platform A bispecific that behaves like a monoclonal antibody

The B-Body^® platform pairs two distinct binding arms onto a human IgG scaffold and solves the chain-pairing problem using the constant domains rather than the variable ones. You get a bispecific you can express, purify, and manufacture like a monoclonal, without touching the biology.

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15,600+

B-Body molecules produced

>30 partners and licenses
>51 VH germlines supported

>0%

Pass purity & yield in 15×15 clinical matrix (in at least one orientation)

zero

Platform engineering rework in CMC

Bispecific formats (1×1, 2×1, 2×2)

The Problem Designed for success in both biology and manufacturing

Most bispecific platforms force a tradeoff. You get the biology you want, but the manufacturing breaks. So when you hand it to a CDMO, it often requires re-engineering. Or the molecule has excellent manufacturing properties but doesn’t maintain the biology you want.

The core problem is multispecific antibody light chain mispairing. When you put two different Fab arms on one antibody, the light chains can pair in the wrong combinations. Solving this issue is challenging.

Fc Region

1. Knobs-into-holes Fc

Drives heavy chain heterodimerization. Clinically validated.

Relies on industry-standard knobs-into-holes design
Drives correct heavy chain heterodimerization
Compatible with standard Fc substitutions for effector function engineering

FAB Arms

2. Proprietary CH3 domain pairs

Makes variable domains plug-and-play.

Proprietary CH3 domain pair replaces CH1/CL domain in one Fab arm
Domain swap forces correct heavy-light chain pairing automatically
Unique CH3 mutations are distinct from the Knobs-into-Holes, mitigating Fc mispairing
No common light chain required, enabling full variable domain diversity
Accepts variable domains from any source without re-engineering
Creates pI asymmetry between arms for simpler polishing chromatography

HEAVY & LIGHT CHAINS

3. Symmetrical chain inversions

Proprietary symmetrical arrangement of heavy and light chains in the Fab arms
Enhances expression yield and stability

SOLE CH1 DOMAIN

4. One-step purification

Anti-CH1 affinity purification drives speed and purity

Only one Fab arm contains a CH1 domain
Anti-CH1 resin captures correctly assembled bispecifics in a single step
A single optimized chain ratio delivers rapid expression and purification
Simplifies in-format discovery screening
Seamlessly transfers to conventional Protein A and IEX purification, supporting manufacturing scale up

Validated performance The data speaks for itself

Unrivaled Bispecific Yield

6–11 g/L

The B-Body^® platform delivers exceptional antibody yields in both transient and stable cell line production.

6–11 g/L from engineered CHO pools and fed-batch production
Achieve 85% final product after one step purification and 95% after second step (lower charts)
Up to 1.8 g/L/day achievable in perfusion cell culture
Validated with two independent stable cell line systems
Substantially higher than any other known bispecific platform
Transient expression predicts manufacturing success

Early (transient) product quality is predictive of manufacturing outcomes. High initial product quality post-capture (> 80%) and typically >95% with two-step purification.

Four stable CHO pools with similar signal sequences and varying chain ratios showed consistent robust expression.

All clones show robust growth and viability with top ProA performance at >7g/L and CH1 at >5g/L CHI1

Analyzed two clones at ~11g/L, generated 85% single step purity and ~100% two step purity. Data courtesy of Catalent.

A CDMO partner conducted a 40L- scale perfusion production run showing final productivity 1.8 g/L/day (Benchmark: 1 – 1.5 g/L/day for high-performing mAbs) and downstream process yield target ~50% with standard mAb process

Excellent Developability Characteristics

The B-Body^® platform virtually eliminates the need for secondary engineering after you choose your lead candidate, eliminating risk and downstream delays.

Excellent Solubility & Sub-Q Compatible Viscosity
Proven Freeze-thaw Stability
Superior storage/Accelerations Stability
Excellent Neutralization Stability

Compatible with Sub-Q administration, achieving 150 mg/mL or greater without exceeding the injectable viscosity limit (<15 cP)

No detectable loss of purity or induced aggregation after 5 cycles of freeze-thaw across four formulations. Studies performed at 100mg/mL

Analysis showed no loss in main peak at -20°C, 4°C and 25°C over four weeks while the 40°C showed approximately 4% main peak loss, Main peak loss at 40°C corresponds to an increase in both HMW and LMW peaks. Studies were performed at 100mg/mL

ProA-purified samples titrated to pH 3.5 and held for 60 minutes neutralized to target pH values. Control was neutralized to pH 5.2 after ProA without low pH hold. Studies performed at 100mg/mL

Broad Range Clinical Antibody Expression

>99% pass in at least one orientation

The 15×15 clinical antibody matrix is the platform's broadest stress test: 225 different bispecifics built from clinical-stage monoclonal antibodies with diverse germlines. If the engineering works, your antibodies should work too.

Antibodies derived from a variety of heavy and light chain germlines
Expressed in 1 mL cultures and purified in one step on anti-CH1 resin
Characterized by capillary electrophoresis (CE), Octet® BLI, and mass spec
>99% of combinations met purity and yield criteria in at least one orientation
Confirms platform compatibility with a broad range of antibody sources, not just cherry-picked examples

The 15×15 result. Color = purity, dot size = yield; boxed cells pass spec

The 15 clinical antibodies in the matrix, with germlines and biophysical properties

Format Selection Flexible geometries deliver on your specific goals

Choose an optimal format based on target density, therapeutic window, and manufacturing.

Beyond 1×1, the B-Body platform expresses several geometries. The right one depends on your biology, and we can test formats side-by-side in their final configuration. All formats are compatible with anti-CH1 and standard Pro A purification methods.

B-Body^® Bispecific 1x1

Key feature Monovalent binding
Advantage Simple, IgG-like
Trade-off No avidity

B-Body^® Bispecific 2x1

Key feature Enables bivalent binding
Advantage Avidity binding to one target
Trade-off More complex

B-Body^® Bispecific 2x2

Key feature Bivalent
Advantage Avidity to both targets
Trade-off More complex

Our platform enables parallel format testing in the final configuration. You get functional data in weeks, not months.

High purity across all B-Body formats

The B-body platform delivers high purity across validated formats. This is purity data from > 1,000 B-Body bispecific antibodies containing a diverse variable domains in transient CHO expressions, 2-step purified from anti-CH1, followed by IEX.

All expressions were performed with a single, optimized chain ratio.
Formats represented are 1x1, 1x2, 2x1, 2x2 and mAbs for reference
1x1’s typically achieve SEC purity target of >95%

Compatibility Fits into your existing workflow

The B-Body platform works with the variable domains, Fc modifications, conjugation chemistries, and manufacturing infrastructure you’d use for a standard mAb.

VH/VL

Variable domains from any source

Discovery libraries, clinical antibodies, partner-supplied sequences, and common light chain campaigns. The 15×15 validation matrix used clinical antibodies from a variety of germlines.

Standard Fc modifications

Discovery libraries, clinical antibodies, partner-supplied sequences, and common light chain campaigns. The 15×15 validation matrix used clinical antibodies from a variety of germlines.

10+

Multiple bispecific formats

1×1, 2×1, 2×2 architectures all supported. The same scaffold accommodates monovalent, bivalent, and tetravalent designs.

ADC

Validated for ADC conjugation

The platform has been validated for cytotoxic payload conjugation (site-specific, cysteine, lysine, and glycan).

κλ

Broad antibody sourcing

The platform is compatible with discovery libraries, diverse germlines, clinical antibodies, partner-supplied sequences, Lambda, Kappa and common light chain antibodies.

Conventional CMC infrastructure

Protein A, IEX, UF, DF are all compatible. B-Body molecules are seamlessly transferred to CDMOs

B-Body flexibility Two ways to access the platform

Most customers engage with the B-Body platform through one of our discovery or expression services. We can discover binders for you using our fast and easy monoclonal antibody discovery services. You can bring your antibodies and plug them into the platform. For organizations that want to run the platform in-house, we offer licensing options.

Full discovery

B-Body Discovery

Start with binders from any source. We screen them as bispecifics in their final format and hand back fully owned, characterized leads with the complete data package.

Explore B-Body Discovery

Expression

B-Body Express

You bring the variable domains. We assemble, express, purify, and characterize them as bispecifics. No common light chain to engineer, several formats and Fc options on one order form.

Explore B-Body Express

B-BODY PLATFORM LICENSING Licensing without the usual barriers

We take the friction out of platform licensing so academia, startups, and large pharma can all build on the B-Body platform. No milestones, no royalties, and full transparency on licensing, data rights, payment timing, and financial terms from term sheet to signed agreement.

All B-Body clinical/commercial licensing runs through our partner Twist Bioscience.

Learn more about licensing »

Research use license

Included with every service project, valid until you license for the clinic

Early decision license

Take the one-year option within 6 months of signing and lock in lower pricing

Standard license

Decide any time up to IND submission, no early option fee

Frequently Asked Questions Quick answers to initial questions

How does B-Body prevent mispairing?

Our patented technology sits in the constant domains, not the variable domains. One Fab arm swaps its CH1/CL for proprietary CH3 domains, so the correct heavy and light chains pair on their own. The variable domains remain untouched, and you don’t need a common light chain.

Do I have to use a common light chain?

No. Each arm keeps its own light chain, kappa or lambda. That’s the elegance of the B-Body design: you bring the best binders for your target instead of forcing them onto a shared light chain.

What antibody sources work on the platform?

Variable domains from any source: antibodies we build, sequences from the public domain, or sequences you supply.

What formats can I build?

1×1, 2×1, and 2×2 bispecific formats.

Can I make an ADC with it?

Yes, absolutely! The platform is validated for common forms of payload conjugation.

Will my CDMO need special equipment?

No, this is the beauty of the B-Body platform. The molecule is based on a human IgG1, so your CDMO can use standard mAb purification processes.

Is the platform in the clinic?

Yes.

What stable cell line technologies are compatible?

Compatible with standard CHO development technologies.

Get in touch Let’s talk about your bispecific program.

Tell us about your targets and goals. A scientist from our team will get back to you — typically within 1 business day.

Your information is 100% confidential.

We don't share your data with third parties, add you to marketing lists without permission, or contact you about anything other than this request. Target biology is treated as confidential. Need an NDA first? Just say so. We'll send one over.

The B-Body^® Platform A bispecific that behaves like a monoclonal antibody

The Problem Designed for success in both biology and manufacturing