Comparison of the Efficacy of Enfortumab Vedotin Between Patients with Metastatic Urothelial Carcinoma Who Were Treated with Avelumab or Pembrolizumab: Real-world Data from a Multi-institutional Study in Japan

Objectives: Enfortumab vedotin (EV) is a novel antibody-drug conjugate approved for metastatic urothelial carcinoma (UC) refractory to prior treatment with immune checkpoint inhibitors (ICIs). However, the difference in efficacy of EV after each ICIs and prognostic factors are not well known. We aimed to compare the efficacy of EV in patients with metastatic UC who were treated with avelumab or pembrolizumab and to identify the prognostic factors.

Methods: The records of 100 patients with advanced metastatic UC who received EV after the administration of either avelumab or pembrolizumab were retrospectively collected from five academic hospitals in Japan.

Results: The median follow-up period was 6.7 months. The median overall survival (OS) and progression-free survival (PFS) in the EV after avelumab/pembrolizumab group were not reached/14.7 months (p = 0.17) and 10.4/5.2 months (p = 0.039), respectively. The objective response rates (ORR) were 66.6% and 46.8% in EV after avelumab and EV after pembrolizumab groups, respectively (p = 0.14). Multivariate analysis identified histological variants, liver metastasis, low serum albumin levels, and high serum CRP level as significant poor prognostic factors. The median OS and PFS of cachexia patients with both low serum albumin levels and high serum CRP levels were 6.0 months and 0.93 months, respectively.

Conclusion: PFS was superior in patients treated with EV after avelumab to EV after pembrolizumab. However, OS showed no significant difference between the two groups. Because the prognosis of patients with cachexia is extremely poor, the initiation of EV should be discussed in these patients.