Study EV-103: Update on durability results and long term outcome of enfortumab vedotin + pembrolizumab in first line locally advanced or metastatic urothelial carcinoma (la/mUC).
Authors: Terence W. Friedlander, Matthew I. Milowsky, Mehmet Asim Bilen, Sandy Srinivas, Rana R. McKay, Thomas W. Flaig, Christopher J. Hoimes, Arjun Vasant Balar, Elizabeth Henry, Daniel P. Petrylak, Carolyn Sasse, Ritesh S. Kataria, Yao Yu, Anne-Sophie Carret, Jonathan E. Rosenberg
Journal: Journal of Clinical Oncology (2021)

4528 Background: Significant unmet need remains for people with cisplatin-ineligible (cis-ineligible) locally advanced or metastatic urothelial carcinoma (la/mUC). In the first-line (1L) setting, carboplatin-based regimens have demonstrated poor tolerability, modest objective response rate (ORR) and limited durability. PD-1/PD-L1 inhibitors demonstrate durable responses; however, only a minority of pts achieve a response (ORR 24-29%). Enfortumab vedotin (EV) is an antibody-drug conjugate (ADC) delivering the microtubule-disrupting agent monomethyl auristatin E (MMAE) to targeted tumor cells expressing Nectin-4. EV has shown an overall survival benefit versus chemotherapy in previously treated la/mUC. Preclinical studies show that ADCs utilizing MMAE can induce immunogenic cell death and may enhance antitumor immunity. Clinical data suggests the combination of EV + pembrolizumab (P) may have the potential to induce greater antitumor activity compared to either agent alone. Preliminary data on EV + P was previously presented, and the FDA granted breakthrough therapy designation to EV + P for the treatment of pts with 1L cis-ineligible la/mUC in Feb 2020. Here we report updated data with 24.9 months median follow-up. Methods: This multi-cohort EV-103 study (NCT03288545) evaluates the safety/activity of EV + P (Dose Escalation/Cohort A). This report highlights 1L cis-ineligible pts treated with 3-week cycles of EV 1.25 mg/kg (Days 1, 8) and P (Day 1). Endpoints include safety/tolerability, investigator response per RECIST v1.1, DOR, PFS, and OS. Results: As of 13 Oct 2020, the median follow-up for the 45 1L la/mUC pts (median age 69 yrs [51-90]) was 24.9 months. The median number cycles of EV + P was 9 (range 1-34). The most common treatment-related adverse events were peripheral sensory neuropathy (56%, 4% ≥G3), fatigue (51%, 11% ≥G3), and alopecia (49%). There was one death reported as possibly related to study treatment (multiple organ dysfunction syndrome) per investigator assessment. Confirmed ORR is 73.3% (95% CI: 58.1, 85.4) including 17.8% CR and an ORR of 57.1% (8/14) in pts with liver metastasis. The median DOR was 25.6 months (95% CI: 8.3, -). Fifty-three percent of the responders had DOR at 24 months. Additionally, the DCR is 93.3%, the median PFS is 12.3 months (95% CI: 8.0, -), and the median OS is not reached. The OS rate at 24 months is 56.3% (95% CI: 39.8, 69.9). Conclusions: EV + P, a platinum-free option, continues to demonstrate promising activity with a durable response profile in 1L cis-ineligible pts with la/mUC. The safety profile is manageable and stable over time with no new safety signals. Cohort K of EV-103 in cis-ineligible pts with la/mUC is actively randomizing pts to EV monotherapy or EV + P to evaluate the contribution of each agent. Clinical trial information: NCT03288545.