Late Breaking Abstract – ESMO 2022: PADCEV® plus KEYTRUDA® in Previously Untreated Cisplatin-Ineligible Patients with Locally Advanced or Metastatic Urothelial Cancer

SUMMARY: The American Cancer Society estimates that in the United States for 2022, about 81,180 new cases of bladder cancer will be diagnosed and approximately 17,100 patients will die of the disease. Bladder cancer is the fourth most common cancer in men, but it is less common in women. A third of the patients initially present with locally invasive or metastatic disease. Patients with urothelial carcinoma are currently treated in the first line setting with a Platinum based chemotherapy regimen, and a checkpoint Inhibitor (PD-1 or PD-L1 inhibitor) in the second line setting. Approximately 50% of patients with advanced urothelial carcinoma are ineligible for Cisplatin-based chemotherapy. There is therefore a critical need for effective and tolerable first line treatment options in locally advanced or metastatic Urothelial Carcinoma.

Enfortumab vedotin-ejfv (PADCEV®) is an Antibody-Drug Conjugate (ADC) that targets Nectin-4, a cell adhesion molecule highly expressed in urothelial cancers and other solid tumors. Nectin-4 has been implicated in tumor cell growth and proliferation. Following binding to Nectin-4 on the cell surface, Enfortumab vedotin 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. Enfortumab vedotin resulted in significantly longer Overall Survival, Progression Free Survival, and a higher Overall Response Rate, than standard chemotherapy, in patients with locally advanced or metastatic urothelial carcinoma, who had previously received Platinum-based treatment and a PD-1 or PD-L1 inhibitor. Preclinical studies with Enfortumab vedotin have shown hallmarks of immune cell death potentially augmented by PD-1/PD-L1 inhibitors, and the rationale for this clinical trial was based on results from a previous cohort study.

Pembrolizumab (KEYTRUDA®) is a fully humanized, Immunoglobulin G4, anti-PD-1, monoclonal antibody, that binds to the PD-1 receptor and blocks its interaction with ligands PD-L1 and PD-L2. By doing so, it unleashes the tumor-specific effector T cells, and is thereby able to undo PD-1 pathway-mediated inhibition of the immune response. Pembrolizumab is the first agent to improve Overall Survival over chemotherapy, in the second line setting, for patients with recurrent, advanced urothelial carcinoma, and a significant proportion of patients who respond, have very durable responses.

EV-103 is a clinical trial conducted to examine the safety and efficacy of Enfortumab vedotin given as monotherapy, and in combination with other anticancer therapies, as first line and second line treatment, for patients with urothelial cancer. This study was conducted in multiple parts for both locally advanced or metastatic urothelial cancer and muscle invasive bladder cancer.

EV-103/KEYNOTE-869 Cohort K is a randomized cohort investigating Enfortumab vedotin alone or in combination with Pembrolizumab as first line treatment in patients with unresectable locally advanced or metastatic urothelial cancer, who are ineligible to receive Cisplatin-based chemotherapy. In this Phase Ib/II randomized study, 149 eligible patients (N=149) were randomly assigned to receive a combination of Enfortumab vedotin 1.25 mg/kg given intravenously on days 1 and 8, and Pembrolizumab 200 mg given intravenously on day 1, every 21 days (N=76) or Enfortumab vedotin monotherapy given on the same schedule (N=73). Ineligibility for Cisplatin-based chemotherapy could be due to at least one of the following: Glomerular filtration rate (GFR) less than 60 mL/min, ECOG Performance Status of 2, Grade 2 or more hearing loss, or New York Heart Association Class III heart failure. No prior systemic treatment for locally advanced or metastatic disease, and adjuvant/neoadjuvant Platinum-based therapy within 12 months prior to randomization, were allowed. The Primary endpoint was confirmed Objective Response Rate (ORR) by BICR (Blinded Independent Central Review). Secondary endpoints included Duration of Response (DOR), Safety, Progression Free Survival (PFS) and Overall Survival (OS).

At a median follow up of 14.2 months, the confirmed Objective Response Rate was 64.5% with the Enfortumab vedotin and Pembrolizumab combination, with 10.5% of patients experiencing a Complete Response and 53.9% of patients experiencing a Partial Response. The median Duration of Response was not reached. The most common Treatment-Related Adverse Events (TRAEs) were peripheral sensory neuropathy (55.6%), fatigue (51.1%), and alopecia (48.9%).

It was concluded that in Cisplatin-ineligible patients with unresectable locally advanced or metastatic urothelial cancer, treatment with Enfortumab vedotin and Pembrolizumab combination in chemo naïve patients, resulted in high Overall Response Rate, along with a safety profile that was tolerable. The authors added that Antibody-Drug Conjugates have the potential to make a greater impact in treating bladder cancer, especially in combination with checkpoint inhibitors, as shown in this trial and these data support ongoing investigations of first line Enfortumab vedotin and Pembrolizumab in patients with locally advanced or metastatic urothelial cancer.

Study EV-103 Cohort K: Antitumor activity of enfortumab vedotin (EV) monotherapy or in combination with pembrolizumab (P) in previously untreated cisplatin-ineligible patients (pts) with locally advanced or metastatic urothelial cancer (la/mUC). Rosenberg JE, Milowsky M, Ramamurthy C, et al. Annals of Oncology (2022) 33 (suppl_7): S808-S869. 10.1016/annonc/annonc1089. LBA73