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.

The widespread use of PARP inhibitors has altered tumor biology in platinum-sensitive ovarian cancer. A recent meta-analysis of heavily pretreated patients, 97% of whom had prior PARP inhibitor exposure, revealed an objective response rate to subsequent therapy of only 17%—far lower than historical expectations, highlighting a critical unmet clinical need.

The ADC mirvetuximab is the first drug to demonstrate an overall survival benefit for platinum-resistant ovarian cancer. This groundbreaking result establishes a higher efficacy standard that subsequent therapies will likely need to meet for regulatory approval and clinical adoption, raising the bar for future drug development.

After a decade with no new therapies improving survival, the landscape for platinum-resistant ovarian cancer is transforming. The recent successes of mirvetuximab, the pembrolizumab/paclitaxel combo, and relacorilant/nab-paclitaxel have all demonstrated statistically significant overall survival benefits, heralding a new era of effective options.

Patients whose ovarian cancer progresses on the folate-targeted ADC mirvetuximab may still respond to a subsequent folate-targeted ADC with a different cytotoxic payload. This suggests that the folate receptor alpha target remains viable and that resistance may be payload-specific, opening new sequencing strategies.

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.

When evaluating data for relapsed/refractory AML, clinicians must look beyond headline response rates. The number of prior therapies a patient has received dramatically impacts outcomes. A trial with a median of one prior treatment will have vastly different results than one with five.

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.