Does Your Bispecific Potency Assay Reflect Full Mechanism of Action?

Bispecific antibodies aren’t just “two antibodies in one”; the therapeutic advantage they provide is a dual, often synergistic mechanism of action. Yet most companies and contract research organizations (CROs) rely on templated platforms, resulting in potency assays that look fine on paper but fail in practice.

When outsourcing support for your potency assays, be mindful of these potential pitfalls:

Poor Assay Design That Fails to Fully Reflect Mechanism of Action (MoA)

Too often, CROs start with the wrong blueprint. They apply off-the-shelf analytical platforms or reuse mono-specific formats that fail to capture both arms of the molecule and a unified MoA. The result? Assays that “bind” but don’t measure therapeutically relevant functional potency. Instead, they:

• Miss bridging/synapse formation
• Ignore cell signaling cascades
• Cannot distinguish dual vs single binding effects

Validation Plans That Don’t Scale Beyond IND

Many CROs validate assays in a Phase-appropriate vacuum—only to discover during GMP release or comparability that key criteria (e.g., linearity, matrix tolerance, reference curve selection) don’t hold up. They require rework, revalidation, and can impose costly delays. In addition, they are subject to:

• Limited method range (fails 50–150% relative potency)
• No robustness data for lot release/stability
• Incompatibility with later-stage regulatory expectations (e.g., ICH Q2(R2), FDA/EMA bispecific guidance)
• Significant interferences from complex biological samples, preventing use for PK and other bioanalytical assessments

Potency assays are a lynch pin in the regulatory package, tying quality of the product to its effectiveness. When working to develop your bispecific potency assay, it is important that the complexity of the product’s function is captured. Bispecific antibodies engage multiple partners to achieve a synergistic outcome, so when outsourcing this key bioassay, your CRO needs to understand the full MoA and bring expertise to the design and development of an approach that yields a meaningful readout.

Look for a service provider who can provide:

Custom Assay Development for Capturing Dual MoA

Bispecific antibodies are not plug-and-play. Each format—T-cell engagers, dual cytokine blockers, immune cell activators—demands an assay architecture that reflects its unique biology.

Ensure your partner CRO:

• Builds fit-for-purpose design for your bispecific format
• Does not rely on off-the-shelf platforms or cookie-cutter workflows
• Visualizes, quantifies, and validates each arm independently

It is important to decode the molecule’s intended MoA, engineer custom formats (binding, bridging, signaling), and optimize specificity, signal-to-noise, and domain resolution to capture the true functional potency of your drug.

Lifecycle-Ready Validation Strategy

From IND to BLA to post-marketing, your validation strategy should be built for scale and regulatory clarity to:

• Align with ICH Q2(R2) and emerging FDA/EMA guidance
• Validate across full potency range (e.g., 50–150%)
• Support assay transfer to GMP, stability programs, and comparability studies

Your assays should be designed not only to meet technical criteria, but to hold up across your product’s lifecycle. Orthogonal readouts can help confirm specificity and reduce cross-reactivity—avoiding costly revalidations and ensuring long-term assay relevance.

With development partners who offer integrated reagent production, automated platforms, and tailored project management, you should expect your CRO to address the unique complexities of bispecific antibodies and to work efficiently, often within accelerated timelines without sacrificing quality. 

Feature / Capability	Other CROs	Prolytix
Assay Design	Typically adopts a standardized, one-size-fits-all approach. Custom methods may require extra fees or lead times.	Offers a personalized collaborative process, tailoring high-quality methods from early-stage development through commercial release that reflect MoA.
Validation	Follows standard regulatory validation protocols (e.g., GLP, GCP), but cross-phase consistency can be a pain point.	Method development packages include validation activities, improving cross-phase consistency. In-house validation across GLP, GCLP, CLIA, and GMP with a strong regulatory inspection track record.
Lifecycle Readiness	Often phase-specific: discovery, validation, or GMP testing may require different vendors, leading to hand-off delays.	Assays designed for the full product lifecycle; offers seamless transitions, integrated project management, and high on-time delivery.
Programmatic Approach	Transactional approach, often lacking direct communication with senior scientific experts, can result in uncertainty regarding key details underlying experimental results. While a transactional approach may work for platform products, with more complex programs, it can result in data gaps and frustrating delays in obtaining satisfying answers to support decision-making.	Proactive management by dedicated senior leadership results in exceptional adherence to budget with on-time delivery from start to finish. Direct collaboration between client, senior scientists, and project management on regular cadence provides for efficient decision-making and real-time updates.

While some CROs offer a modular, phase-specific service model that is not designed to track a therapeutic, Prolytix delivers integrated, customizable services across the full therapeutic lifecycle—with strong validation, MoA–biomarker integration, and dedicated project management.