How to Find the Right ADC CDMO

Antibody-drug conjugates create a sourcing challenge that is different from choosing a conventional biologics manufacturer.

An ADC combines several technically demanding components:

• an antibody
• a linker
• a cytotoxic or otherwise active payload
• a conjugation process
• purification
• analytical characterization
• potentially sterile drug product manufacturing

A CDMO may be excellent at one part of that chain and still be the wrong partner for the overall program.

The first step is therefore not to search for the biggest ADC manufacturer.

It is to define which parts of the ADC manufacturing process you actually need a partner to handle.

An ADC CDMO is a contract development and manufacturing organization that supports development or manufacturing of antibody-drug conjugates.

Depending on the company and facility, services may include:

• antibody manufacturing
• payload manufacturing
• linker synthesis
• linker-payload manufacturing
• conjugation
• purification
• analytical development
• formulation
• fill finish
• GMP manufacturing
• stability testing

Some CDMOs provide an integrated ADC offering.

Others specialize in one or two parts of the manufacturing chain.

Both approaches can work.

What matters is whether the operating model fits the sponsor's program.

This is one of the most important decisions in ADC sourcing.

A sponsor may choose:

one integrated CDMO

or

multiple specialized manufacturing partners

An integrated provider may handle antibody production, linker-payload work, conjugation, drug product, or several of those steps.

A multi-partner strategy might use one manufacturer for the antibody, another for the payload, and a specialist for conjugation.

Integration can simplify transfers and coordination.

Specialization can give the sponsor access to deeper expertise in individual areas.

There is no universal best model.

The answer depends on the program's technology, internal capabilities, stage, risk tolerance, and existing supplier relationships.

Conjugation is the step that brings the antibody and linker-payload together.

It is central to ADC manufacturing.

Sponsors should understand whether the CDMO has experience with the intended conjugation strategy and whether the process can be transferred or developed at the proposed facility.

Questions may include:

• What conjugation approaches does the facility support?
• Is process development available?
• What scale is practical?
• How is the process controlled?
• What purification steps follow conjugation?
• What analytical methods are used to characterize the product?

A company that broadly advertises ADC manufacturing may still have limitations around the specific conjugation approach used by the sponsor.

Many ADC payloads are highly potent.

That makes containment a major manufacturing consideration.

The sponsor may need to evaluate:

• occupational exposure controls
• containment strategy
• facility design
• material handling
• cleaning procedures
• equipment segregation
• waste handling
• transfer between manufacturing areas

A facility that can manufacture biologics is not automatically equipped to handle potent ADC payloads.

This is one of the reasons facility-level diligence matters so much in ADC sourcing.

Some ADC programs require specialized chemistry for the linker, payload, or linker-payload intermediate.

That work may sit closer to highly potent small molecule manufacturing than conventional biologics manufacturing.

If the ADC CDMO does not manufacture these components internally, the sponsor should understand how they are sourced.

That raises practical questions:

• Who qualifies the supplier?
• Who coordinates material release?
• Where does linker-payload manufacturing occur?
• How are materials transported?
• What happens if an upstream supplier slips its schedule?

The conjugation process depends on those materials arriving on time and meeting specification.

The antibody itself may be manufactured by the ADC CDMO, an external biologics manufacturer, or supplied by the sponsor.

That decision affects technology transfer, scheduling, analytical testing, storage, and material logistics.

Sponsors should establish early:

• who makes the antibody
• where it is released
• how it reaches the conjugation facility
• what specifications are required
• whether the antibody process is already established

A strong ADC manufacturing strategy has to account for the full chain, not only the final conjugation step.

After conjugation, the product generally needs purification and processing to reach the required quality profile.

Sponsors should investigate whether the proposed facility can support the purification strategy required by the process.

This may involve:

• chromatography
• filtration
• concentration
• buffer exchange
• impurity removal

The exact process is product-specific.

The important point during CDMO selection is that downstream processing needs to be evaluated with the same care as the conjugation step itself.

ADC characterization can be complex.

Sponsors may need analytical capabilities related to:

• identity
• purity
• aggregation
• potency
• free payload
• residual impurities
• drug-to-antibody ratio
• stability

Not every ADC manufacturer has the same analytical depth.

If analytical methods are still being developed, the CDMO's development expertise may be particularly important.

If methods are mature, the focus may shift more toward transfer, validation, and routine execution.

Drug-to-antibody ratio, often abbreviated DAR, is an important characteristic of many ADC products.

The conjugation process needs to produce a product with an appropriate and controlled distribution.

Sponsors should understand how the CDMO monitors and controls the conjugation process and how DAR is characterized analytically.

This is not a reason to choose one manufacturer based on a single metric.

It is one of several technical factors that help determine whether the facility and process are a good fit.

Some ADC CDMOs can support sterile drug product manufacturing after conjugation.

Others stop at bulk drug substance.

If the sponsor also needs fill finish, it should decide whether to:

• keep conjugation and fill finish with one provider
• transfer the product to a specialized sterile manufacturer

The decision may depend on:

• facility capabilities
• product stability
• scale
• container format
• scheduling
• experience handling potent products

An early clinical ADC program may need significant process development and flexibility.

A later-stage program may place more emphasis on:

• process robustness
• validation
• commercial scale
• supply reliability
• long-term capacity

A manufacturer that is excellent for Phase I work is not automatically the right commercial partner.

Sponsors should understand how the CDMO supports programs as they mature.

The facility proposed for ADC manufacturing should be part of regulatory diligence.

Available FDA Form 483 information and other inspection history can help identify questions that deserve further review.

Regulatory information should be evaluated in context.

A historical observation does not automatically make a manufacturer unsuitable.

Formal quality and regulatory qualification remains the sponsor's responsibility.

ADC schedules can depend on more than one manufacturing step.

The antibody may need to be available before conjugation.

The linker-payload may come from another facility.

Analytical testing may create its own timeline.

Fill finish may require a separate manufacturing slot.

Sponsors should therefore ask about the critical path, not just the conjugation date.

A useful timeline should account for every step that could delay the program.

An ADC can involve several manufacturing steps, sometimes at different organizations. Mapping them early clarifies which capabilities each partner needs:

1. Antibody→
2. Linker and payload→
3. Conjugation→
4. Purification→
5. Analytics→
6. Fill finish

The antibody itself is often sourced through a monoclonal antibody CDMO, and ADCs sit within the broader biologics CDMO landscape.

PCN helps sponsors compare facilities on conjugation, containment, analytics, and regulatory context, then request structured introductions with the manufacturers that appear relevant to the ADC program.