In the race to bring new antibody-drug conjugates (ADCs) to market, one challenge often slows even the most promising programs: detecting and characterizing novel payloads. When no commercial anti-payload antibodies exist — and the payload structure itself is new to the scientific community — researchers face a bottleneck in assay development, PK/PD studies, and stability testing.

At ProSci, we’ve built a reputation for solving this exact problem. Our team works hand-in-hand with therapeutic companies to design and deliver custom, research-use-only (RUO) anti-payload antibodies — accelerating ADC programs and helping clients generate critical data faster.

Why Novel Payloads Need Novel Solutions

ADC payloads — the cytotoxic “warheads” that give these drugs their potency — are often small molecules that are poorly immunogenic on their own. When the payload’s structure and mechanism of action are novel, there’s rarely an off-the-shelf antibody that can detect it.

Even for published payload chemistries, commercially available antibodies may lack the specificity or sensitivity required for rigorous preclinical testing. That’s where custom development becomes essential.

Our Approach to Custom Anti-Payload Development

Our process is designed to deliver highly specific, high-quality antibodies — even for payloads no one has ever targeted before:

1. Collaborative Immunogen Design
   We work with the client’s payload chemistry team to design a safe, effective immunogen, typically by conjugating the payload to a carrier protein like KLH or BSA to stimulate an immune response.
2. Careful Conjugation Chemistry
   We select chemistries that preserve the key epitopes, ensuring antibodies recognize the active structure — not just the carrier or linker.
3. Targeted Immunization
   We select the host species (rabbit, goat, sheep, llama/alpaca, chicken) most likely to yield strong, diverse responses.
4. Affinity Purification & Specificity Screening
   Using linker-payload and carrier-only conjugates, we purify antibodies that bind only the payload of interest and remove any cross-reactive antibodies.
5. Delivery of RUO-Grade Antibodies
   We deliver antibodies ready for use in ELISA, LC-MS/MS enrichment, DAR analysis, stability studies, and more.

Case Study: Monoclonal Success in a Novel Payload Program

Last year, a therapeutic company approached ProSci with a challenging request: develop a monoclonal antibody against a payload that had never been targeted before.

Within months, we delivered a high-specificity monoclonal that became a cornerstone of their preclinical PK/PD assays. That antibody’s performance helped the client advance their ADC program toward IND-enabling studies.

The result? Not only a scientific win, but also a partnership that led them to refer other companies to ProSci — including a new discussion on exploring polyclonal strategies for similar payloads.

From Polyclonal to Monoclonal: Choosing the Right Path

For many ADC projects, starting with a polyclonal antibody can be the smartest move — and not just because it’s more cost-effective.

Why start with a polyclonal?

• Faster timelines — often 8–12 weeks to functional data.
• Broader epitope coverage — more chances to detect the payload in multiple assay formats.
• Lower upfront risk — validate that the target is detectable before committing to monoclonal development.
• Better monoclonal targeting — once the polyclonal proves successful, it can guide monoclonal screening for equal or better performance.

When to go straight to a monoclonal:

• If reproducibility, regulatory alignment, and long-term supply security are needed early.
• If the program is already validated and requires a defined, single-epitope reagent.

At ProSci, we offer both paths — starting with a polyclonal for speed and flexibility, or moving directly into monoclonal development for clients who are ready. Either way, our goal is the same: deliver a high-performance anti-payload antibody that keeps your ADC program moving forward.

Ready to Accelerate Your Payload Program?

Whether you need the speed and coverage of a polyclonal or the precision and reproducibility of a monoclonal, ProSci can help you get there. Our team has a proven track record in both approaches — and the expertise to guide you to the right starting point for your goals, budget, and timeline.

Let’s turn your novel payload into actionable data.