The clinical strategy of 'saving' the most effective drugs for later lines of therapy may be flawed. Data indicates that 20-30% of patients with metastatic breast cancer do not go on to receive a subsequent line of treatment after progression, arguing for the use of optimal therapies like ADCs earlier in the disease course.

Real-world data shows that in platinum-sensitive ovarian cancer patients who have progressed on PARP inhibitors, subsequent platinum-based chemotherapy has a surprisingly low response rate of only 20%. This quantifies a significant opportunity for highly active ADCs to potentially replace platinum in this growing patient population.

Unlike early ADCs requiring high biomarker expression (e.g., mirvetuximab), next-generation agents show efficacy even in low-expressing tumors. This allows for broader, "all-comer" clinical trial inclusion criteria instead of biomarker-gated entry, potentially expanding patient access to these novel therapies.

A new wave of antibody-drug conjugates (ADCs) is transforming ovarian cancer treatment. These 'heat-seeking missiles' deliver potent chemotherapy payloads directly to tumor cells, achieving response rates from 23% to over 60% in biomarker-selected populations. This far surpasses the efficacy of conventional chemotherapy in resistant settings.

Early clinical trial data for the ADC mirvetuximab shows a response rate of 39% in patients with one to three prior lines of therapy. This rate drops significantly for patients with four or more lines, supporting prioritization of this drug earlier in the platinum-resistant setting.

In metastatic breast cancer, approximately one-third of patients are unable to proceed to a second line of therapy due to disease progression or declining performance status. This high attrition rate argues for using the most effective agents, such as ADCs, in the first-line setting.

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.

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.

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.