Contrary to concerns about tolerating Enfortumab Vedotin (EV) after major surgery, 80% of muscle-invasive bladder cancer patients who began the adjuvant phase in the KEYNOTE B15 trial successfully completed it. This suggests the regimen is more manageable post-cystectomy than anticipated.

The B15 trial shows EV-Pembro is superior to chemotherapy in muscle-invasive bladder cancer. However, the true benchmark is now the Niagara study (chemo + durvalumab), which already beat chemo alone. The debate will focus on whether EV-Pembro offers a significant enough improvement to become the definitive standard over this new chemo-IO combination.

Despite the perception that cisplatin-ineligible patients have worse disease biology, the pathologic complete response rates to neoadjuvant EV Pembro were nearly identical (56-57%) in both cis-ineligible (KEYNOTE-905) and cis-eligible (KEYNOTE-B15) trials. This suggests the regimen's high efficacy may overcome underlying biological differences.

While both the B15 (EV Pembro) and Niagara (Gem-Cis-Durvalumab) trials were positive, B15 demonstrated a significantly higher pathologic complete response rate (56% vs 37%) and more favorable hazard ratios for survival endpoints. This suggests EV Pembro is the "more positive" regimen and likely the preferred standard of care.

A significant criticism of the pivotal KEYNOTE-564 trial is that only half the patients in the control arm received standard-of-care immunotherapy upon relapse. This lack of subsequent optimal treatment complicates the interpretation of the overall survival benefit, raising questions about its true magnitude.

Perioperative enfortumab vedotin-pembrolizumab (EV-Pembro) is surprisingly well-tolerated on a per-cycle basis compared to the traditional GEMSYS chemotherapy regimen. This challenges preconceived notions about the toxicity of this powerful combination, though cumulative toxicity over longer durations remains a key factor.

Historically, aggressive variants like micropapillary went directly to surgery. However, recent data suggests these patients do poorly due to micrometastatic disease. The trend is now to give neoadjuvant EV-Pembro to treat systemic disease, even with limited specific evidence.

Comparing control arms from the TOGA (11 months OS), KEYNOTE-811 (16 months), and HORIZON (19 months) trials reveals a steady improvement in patient outcomes. This trend, likely due to better second-line therapies and supportive care, makes it harder for new agents to show a relative benefit.

While KEYNOTE-905 showed dramatic survival benefits with neoadjuvant plus adjuvant EV-pembrolizumab, its design makes it impossible to isolate the benefit of each phase. The high (57%) pathologic complete response after neoadjuvant therapy alone suggests many patients may be overtreated with adjuvant cycles, risking unnecessary long-term toxicity like neuropathy.