With multiple ADCs available, an emerging sequencing strategy is to alternate between different mechanisms of action, such as following a microtubule toxin-based ADC with a topoisomerase-1 inhibitor payload. This approach aims to avoid compounding specific toxicities, like neuropathy, and potentially circumvent resistance, though it is a strategy born from logic rather than clinical trial data.

To mitigate the severe toxicity of promising pan-RAS inhibitors, companies are adopting antibody-drug conjugate (ADC) technology. This marks a strategic expansion for ADCs, moving beyond traditional cytotoxic chemotherapy payloads to delivering highly specific targeted therapies, aiming to improve the therapeutic window of potent new drug classes.

The primary reason Antibody-Drug Conjugates (ADCs) stop working is payload resistance, a shift from the traditional belief that failure stems from tumors losing the target antigen. This insight drives development of multi-payload ADCs to overcome this resistance mechanism.

When planning treatment for patients who will receive multiple antibody-drug conjugates (ADCs), the prevailing clinical strategy is to focus on alternating the drug's payload (e.g., a tubulin inhibitor vs. a topoisomerase I inhibitor). This approach is believed to be more effective at overcoming resistance than alternating the cell-surface target.

When sequencing antibody-drug conjugates (ADCs) for SCLC, resistance may be driven more by the cytotoxic payload (e.g., a topoisomerase 1 inhibitor) than the antibody's target antigen. This suggests prior exposure to a similar payload class could predict non-response, even when using an ADC with a different target.

Unlike older antibody-drug conjugates (ADCs), newer agents are designed so their chemotherapy payload can diffuse out of the target cell and kill nearby tumor cells that may not even express the target antigen. This "bystander effect" significantly enhances their anti-tumor activity.

As multiple effective Antibody-Drug Conjugates (ADCs) become available, the primary clinical challenge is no longer *if* they work, but *how* to use them best. Key unanswered questions involve optimal sequencing, dosing for treatment versus maintenance, and overall length of therapy, mirroring issues already seen in breast cancer.

A key principle for clinicians is that an antibody-drug conjugate's adverse events are primarily dictated by its linker-payload (e.g., deruxtecan, vedotin), not its specific antibody target. This allows for anticipating toxicities like neuropathy or GI issues based on the payload class, creating a predictable framework for management across different ADCs.

Despite prior speculation of a slowdown, the prominence of Antibody-Drug Conjugates (ADCs) in first-in-human trials at ASCO is "skyrocketing." The volume of new ADC trials now nearly equals that of small molecules and far surpasses traditional monoclonal antibodies.