Efficacy and safety of transcatheter arterial infusion of immune checkpoint inhibitors in locoregional unresectable or in-transit acral melanoma: A multi-center real-world study.

9546 Background: Acral melanoma (AM) is highly invasive. Standard treatment options, including surgical resection and systemic immunotherapy, frequently yield insufficient control over local lesions. Although various local treatment strategies are currently available, such as isolated limb perfusion (ILP), isolated limb infusion (ILI), intralesional therapies, and radiotherapy, there is still no universally recognized safe and effective method. Previous studies have suggested that transcatheter arterial infusion (TAI), as a locoregional therapeutic strategy, may enhance the management of local lesions through targeted drug delivery. However, the existing literature on the efficacy and safety of TAI utilizing immune checkpoint inhibitors (ICIs) is limited. The aim of this study was to assess the efficacy and safety of TAI of ICIs in patients diagnosed with AM, as well as to investigate clinical factors that may affect treatment outcomes. Methods: This study involved a retrospective analysis of patients with AM who underwent TAI of ICIs across multiple centers. Participants received TAI of PD-1 inhibitors or a combination of PD-1 and CTLA-4 inhibitors every three weeks, in conjunction with systemic therapy. The primary endpoint was the objective response rate (ORR), while secondary endpoints included the disease control rate (DCR), progression-free survival (PFS) of locoregional lesions, duration of response (DoR), and overall survival (OS). Results: A total of 44 patients with AM were enrolled and analyzed between May 2019 and January 2025. All participants had received at least two TAI treatments and had at least one evaluable locoregional lesion in the extremities, as determined by enhanced MRI or CT imaging. The cohort consisted of 23 females (52%) and 21 males (48%), with a median follow-up period of 10.6 months. The overall ORR was 36.4%, and the DCR was 86.4%. The ORR and DoR for lesions treated with TAI were 40.9% and 90.1%, respectively. Five patients (11%) achieved a complete response (CR), one of whom demonstrated a pathological complete response. The median DoR and OS were recorded at 11.8 months and 32.2 months, respectively. First-line treatment exhibited a significantly higher ORR (82.4% vs. 14.8%, P < .001) and longer PFS (24.9 months vs. 3.5 months, P < .001) compared to subsequent-line treatments. Adverse events were primarily classified as grade 1-2, with no instances of grade 4-5 events, and there were no treatment-related discontinuations or fatalities. Conclusions: This study provides evidence for the safety of TAI of ICIs and suggests that it may represent an effective first-line treatment option for Chinese patients with locoregional unresectable lesions of AM, demonstrating significant local control efficacy in real-world clinical settings.