While platinum chemotherapy is considered the standard treatment after a patient progresses on a first-line ADC-IO combination, experts admit this is a standard "based on nothing." There is no clinical trial data to prove its efficacy in this specific setting; it serves only as a placeholder for new clinical trials.

The traditional six-month timeframe for defining platinum sensitivity is being challenged. A growing theory suggests that tumors progressing while on a PARP inhibitor have a distinct biology that responds poorly to subsequent platinum, indicating a potential need to move directly to therapies like ADCs.

The EV Pembro combination is the new first-line standard for metastatic bladder cancer, replacing platinum chemotherapy. This shift leaves clinicians without clear, trial-backed evidence for second-line treatment, as previous trials for other agents were all designed for post-platinum progression.

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.

Despite the KEYNOTE-B96 trial showing a statistically significant survival benefit, the expert's enthusiasm for adding pembrolizumab in platinum-resistant ovarian cancer is only "neutral." This hesitation stems from challenges in sequencing it with other effective therapies and uncertainty about which patient subgroups truly benefit.

An expert speculates that the durable responses and plateauing four-year survival curve from the EV302 trial indicate a potential cure rate of 30% in metastatic bladder cancer, a dramatic improvement over historical outcomes of 5-10%.

The demonstrated superiority of the enfortumab vedotin (EV) and pembrolizumab combination over platinum chemotherapy has effectively made the Galski criteria, used for determining cisplatin eligibility, irrelevant. This marks a major paradigm shift in how frontline bladder cancer is approached, moving beyond platinum-based decisions.

A key lesson in bladder cancer is that patient attrition is rapid between lines of therapy; many who relapse from localized disease never receive effective later-line treatments. This reality provides a strong rationale for moving the most effective therapies, like EV-pembrolizumab, to earlier settings to maximize the number of patients who can benefit.