Real-world effectiveness and safety of RC48-ADC combined with PD-1 inhibitors for patients with metastatic urothelial carcinoma: A retrospective multicenter study.

e16551 Background: RC48 antibody-drug conjugate (ADC) combined with PD-1 inhibitor has significantly impacted the treatment of metastatic urothelial carcinoma (mUC). This study aimed to assess the efficacy and safety of RC48 combined with PD-1 inhibitor as a first-line treatment for patients with mUC in a real-world clinical setting. Methods: We retrospectively collected data from patients with mUC who received RC-48 in combination with PD-1 inhibitor as first-line therapy between July 2021 and February 2024 from 3 medical centers to assess real-world antitumor efficacy and safety. Results: 63 patients with mUC were collected, with a mean age of 67 years and 71.4% were male. The most common site of metastasis was lymph nodes (77.8%), followed by lung (31.7%), bone (23.8%), liver (19.0%), and so on. The response rates were as follows: complete response in 12 patients (19.0%), partial response in 33 cases (52.4%), and stable disease in 10 cases (15.9%). The objective response rate was 71.4%, and the disease control rate was 87.3%. The median progression-free survival was 10.5 (8.8-14.6) months and the median overall survival was not reached. The most reported treatment-related adverse events were fatigue (36.5%), anemia (34.9%), pruritus (33.3%), peripheral sensory neuropathy (28.6%), and nausea (28.6%), etc. Grade III TRAEs occurred in seven patients (11.1%) and no grade IV or V TRAEs occurred. Conclusions: The use of 3-weekly cycles of RC48 in combination with PD-1 inhibitor as first-line therapy is both effective and safe for real-world patients with la/ mUC, regardless of disease status or impaired renal function. Clinical trial information: 2024KY277 . Patient demographics and clinical features in metastatic urothelial carcinoma treated. Patient Characteristics Values Total number 63 Gender(%) Male 71.4% Female 28.6% Age, Median（years） 50-92 ≥70, No. (%) 36.5% ECOG score(%) 0 49.2% 1 39.7% ≥2 11.1% Cr, median (umol/L) 43-296 Baseline creatinine clearance rate(%) ≥ 60 ml/min 52.4% 30–60 ml/min 39.7% &lt; 30 ml/min 7.9% Primary lesion(%) Bladder 54.0% Ureter/Renal pelvis 46.0% Prior locoregional curative treatments(%) Radical tumor resection 46.0% Partial tumor resection 15.9% Diagnostic tumor resection 30.2% Tumor biopsy 7.9% Organizational differentiation(%) UC without differentiation 92.0% UC with squamous differentiation 4.8% UC with glandular differentiation 3.2% Metastatic site(%) Lymph nodes 77.8% Lung 31.7% <jats:td colspan="1" content-type="row-heading" rowsp