Updated results from phase 1b/II (EV-103) trial of Padcev with pembrolizumab for first-line treatment for advanced urothelial cancer. Seattle Genetics + Astellas

Seattle Genetics, Inc.and Astellas Pharma Inc. announced updated results from the phase 1b/II clinical trial EV-103 in previously untreated patients with locally advanced or metastatic urothelial cancer who were ineligible for treatment with cisplatin-based chemotherapy. Forty-five patients were treated with the combination of Padcev (enfortumab vedotin-ejfv) and pembrolizumab and were evaluated for safety and efficacy. After a median follow-up of 11.5 months, the study results continue to meet outcome measures for safety and demonstrate encouraging clinical activity for this platinum-free combination in a first-line setting. Updated results will be presented during an oral session on Friday, February 14 at the 2020 Genitourinary Cancers Symposium in San Francisco (Abstract #441). Initial results from the study were presented at the European Society of Medical Oncology Congress in September 2019.In the study 58 percent (26/45) of patients had a treatment-related adverse event greater than or equal to Grade 3: increase in lipase (18 percent; 8/45), rash (13 percent; 6/45), hyperglycemia (7 percent; 3/45) and peripheral neuropathy (4 percent; 2/45); these rates were similar to those observed with Padcev monotherapy. Eighteen percent (8/45) of patients had treatment-related immune-mediated adverse events of clinical interest greater than or equal to Grade 3 that required the use of systemic steroids (arthralgia, dermatitis bullous, pneumonitis, lipase increased, rash erythematous, rash maculo-papular, tubulointerstitial nephritis, myasthenia gravis). None of the adverse events of clinical interest were Grade 5 events. Six patients (13 percent) discontinued treatment due to treatment-related adverse events, most commonly peripheral sensory neuropathy. As previously reported, there was one death deemed to be treatment-related by the investigator attributed to multiple organ dysfunction syndrome. The data demonstrated the combination of Pa Padcev plus pembrolizumab shrank tumors in the majority of patients, resulting in a confirmed objective response rate (ORR) of 73.3 percent (33/45; 95% Confidence Interval (CI): 58.1, 85.4) after a median follow-up of 11.5 months (range, 0.7 to 19.2). Responses included 15.6 percent (7/45) of patients who had a complete response (CR) and 57.8 percent (26/45) of patients who had a partial response. Median duration of response has not yet been reached (range 1.2 to 12.9+ months). Eighteen (55%) of 33 responses were ongoing at the time of analysis, with 83.9% of responses lasting at least 6 months and 53.7% of responses lasting at least 12 months (Kaplan-Meier estimate). The median progression-free survival was 12.3 months (95% CI: 7.98, -) and the 12-month overall survival (OS) rate was 81.6 percent (95% CI: 62 to 91.8 percent); median OS has not been reached. Comment: Keytruda has won FDA approval for first-line bladder cancer bbased on its KEYNOTE-052 trial, which demonstrated an ORR of 29% in 310 patients, with 7% experiencing a complete response and 22% partial responses. In comparison, the Padcev combination seems to be superior to Keytruda alone, at least with this updated early-stage data.