Supplementary Material for: Experience and prognostic analysis with avelumab switch maintenance treatment in metastatic urothelial carcinoma

Introduction: Avelumab is approved for metastatic urothelial carcinoma (mUC) maintenance therapy and prolongs overall survival (OS). We explored trends related to avelumab treatment of mUC patients.
Methods: A total of 72 patients with mUC treated with first-line chemotherapy, from January 2019 to November 2022, at our affiliated institutions, were analyzed. We compared clinical parameters and the prognosis of patients treated with avelumab (Ave; n=43), because of progression during first-line chemotherapy, with untreated patients (Ave-untreated; n=29). Among the Ave-treated group, we classified patients showing a complete or partial response or stable disease in their best response to avelumab maintenance therapy as avelumab (Ave)-suitable patients; these were retrospectively analyzed. Potential prognostic factors, including the geriatric nutritional risk index (GNRI) for determining patients suitable for Ave, were evaluated.
Results: The basic clinical parameters of patients when first-line treatment was initiated were not statistically different between the two groups. The Ave-suitable group (median 26.6 months, 95% confidence interval [CI]: 19.4–not reached [NR]) showed significantly longer median OS after first-line treatment than the Ave-untreated group (median 12.0 months, 95% CI: 7.5–NR) with tolerable adverse events. The cut-off values of prognostic factors were set by receiver operating characteristic curve. Low age and GNRI sustainability revealed as significant prognostic factors for being Ave-suitable both in univariate and multivariate analysis.
Conclusion: In mUC, avelumab maintenance prolonged OS within tolerable safety profiles. GNRI sustainability may be used as biomarker to predict being Ave-suitable.