A "tsunami" of antibody-drug conjugates (ADCs) are in development for ovarian cancer, but many share the same TOP1 inhibitor payload. This creates a significant future clinical challenge: after a patient progresses on one such ADC, it is unknown if another with the same payload will be effective, creating an urgent need for sequencing data.

The current ADC landscape is saturated with similar drugs using topo-isomerase-1 inhibitors. This creates a market opportunity and an ethical imperative to develop new payloads with different mechanisms of action to treat patients who will inevitably develop resistance to the current generation of therapies.

As numerous antibody-drug conjugates (ADCs) move to frontline cancer therapy, a key concern emerges: most use a small number of payloads (like topo-1 inhibitors). There is pessimism about whether sequencing different ADCs that share the same payload will be effective.

Dr. O'Malley avoids using multiple ADCs with the same TOPA-1 payload sequentially due to a lack of data. However, he will reuse a target if the subsequent ADC has a different, non-cross-resistant payload, such as an anti-microtubulin. This is a practical strategy to manage resistance in a data-sparse environment, prioritizing payload diversity over simply switching targets.

Retrospective data shows that using one Antibody-Drug Conjugate (ADC) after another, particularly those with the same class of payload like TOP1 inhibitors, results in a low response rate of 10-20%. This creates a significant unmet need and a major clinical challenge for patients who progress on a first-line ADC.

A surprising trend in ovarian cancer is the consistent efficacy of antibody-drug conjugates (ADCs) with a TOPA1 payload. Regardless of the specific cell surface target, these agents are achieving response rates around 50%, suggesting the payload's potency is the primary driver.

A promising future strategy for ovarian cancer involves combining two different ADCs. The key to this approach is selecting agents with distinct payloads (e.g., an anti-microtubulin and a TOPA-1 inhibitor) whose side effect profiles do not overlap. This could maximize anti-tumor efficacy while maintaining a manageable toxicity burden for patients, offering a novel combination paradigm.

Most new antibody-drug conjugates (ADCs) for ovarian cancer use the same topoisomerase-1 (Topo1) inhibitor payload. This similarity will likely prevent their sequential use due to cross-resistance, forcing clinicians into a "one-shot" scenario where they must choose the single best Topo1-based ADC upfront for a patient.

As more antibody-drug conjugates (ADCs) become available, a key concern is resistance to the cytotoxic payload. If a tumor develops resistance to a topoisomerase-1 inhibitor from one ADC, it may not respond to other ADCs using the same payload, regardless of their different antibody targets, complicating future treatment sequencing.