SUMMARY: The FDA on December 18, 2019, granted accelerated approval to PADCEV® (Enfortumab vedotin-ejfv), for adult patients with locally advanced or metastatic urothelial cancer who have previously received a Programmed Death receptor-1 (PD-1) or Programmed Death-Ligand1 (PD-L1) inhibitor, and a Platinum-containing chemotherapy in the neoadjuvant/adjuvant, locally advanced or metastatic setting. The American Cancer Society estimates that in 2019, approximately 80,470 new cases of Bladder Cancer will be diagnosed and 17,670 patients will die of the disease. Patients with urothelial carcinoma are currently treated in the first line setting with a Platinum based chemotherapy regimen and a Check Point Inhibitor (PD-1 or PD-L1 inhibitor) in the second line setting. Treatment options for patients who progress after first and second line therapies are limited, with poor outcomes. The response rates with standard chemotherapy in this patient population, is about 10%.
PADCEV® is an Antibody-Drug Conjugate (ADC) that targets Nectin-4, a cell adhesion molecule highly expressed in urothelial cancers and other solid tumors. Following binding to Nectin-4 on the cell surface, PADCEV® becomes internalized and is processed by lysosomes, with the liberation of its cytotoxic payload, Monomethyl auristatin E, which in turn disrupts microtubule assembly, leading to cell cycle arrest and apoptosis. In a Phase I dose-finding study of PADCEV®, the Objective Response Rate (ORR) was 42% among patients with advanced urothelial cancer, who previously received treatment with a PD-1/PD-L1 inhibitor.
This FDA approval was based on the results from the pivotal Phase II EV-201 study, which is an open-label, single-arm, multicenter trial in which 125 patients with locally advanced or metastatic urothelial cancer who received prior treatment with a PD-1 or PD-L1 inhibitor and Platinum-based chemotherapy were enrolled. Patients received PADCEV® 1.25 mg/kg on days 1, 8, and 15 of a 28-day cycle, until disease progression or unacceptable toxicity. The median age was 69 years. The Primary endpoint was ORR as assessed by blinded Independent Central Review. Secondary endpoints included Duration of Response, Progression Free Survival (PFS), Overall Survival (OS), Safety and Tolerability.
The ORR was 44%, with 12% Complete Responses and 32% Partial Responses. Overall, 84% of evaluable patients showed some degree of tumor shrinkage. The responses were noted at a median of 1.8 months after treatment initiation and the median Duration of Response was 7.6 months. These objective responses were seen in all patient subgroups evaluated, including those with poor prognostic features. The median PFS was 5.8 months, and the median Overall Survival was 11.7 months. The most common adverse reactions were fatigue, alopecia, decreased appetite and peripheral neuropathy. Blood glucose levels should be monitored closely in patients with, or at risk, for diabetes mellitus or hyperglycemia.
It was concluded from this study that treatment with PADCEV® demonstrated clinically meaningful Objective Response Rate, in patients with advanced metastatic urothelial cancer, who received prior treatment with a PD-1 or PD-L1 inhibitor and Platinum-based chemotherapy, thus fulfilling an unmet need. PADCEV® is the first Nectin-4-directed Antibody-Drug Conjugate to receive FDA approval, and a Phase III study is underway comparing PADCEV® against standard single-agent chemotherapy, in patients with advanced, previously treated metastatic urothelial cancer. EV-201: Results of enfortumab vedotin monotherapy for locally advanced or metastatic urothelial cancer previously treated with platinum and immune checkpoint inhibitors. Petrylak DP, Balar AV, O’Donnell PH, et al. DOI: 10.1200/JCO.2019.37.18_suppl.LBA4505 Journal of Clinical Oncology 37, no. 18_suppl (June 20, 2019) 4505-4505.
