Immunotherapy in the Treatment of Metastatic Eccrine Porocarcinoma

Background: Metastatic uveal melanoma (MUM) poses a significant challenge in oncology, with limited treatment options and poor long-term survival rates.Local therapies, including resection, radiation therapy, and systemic treatments such as tebentafusp, represent advancements in managing metastatic UM, particularly in HLA-A*02:01-positive patients.Methods: This retrospective, real-world study conducted at Princess Margaret Cancer Centre between 2021 and April 2024 aimed to evaluate the impact of local therapy in conjunction with tebentafusp on overall survival (OS) in patients with metastatic UM.Local treatment modalities included radiofrequency ablation (RFA), transarterial chemoembolization (TACE), stereotactic body radiotherapy (SBRT), and radioembolization with yttrium-90 (Y90).The frequency, type, and timing of local therapy were analyzed.Baseline LDH results and the size of the primary tumor at diagnosis were considered when analyzing the population.Overall survival (OS) was assessed using risk regression via the Cox proportional hazards model.All analyses were performed using the STATA statistical package, version 15.0.Results: Data from 53 patients receiving tebentafusp were analyzed, with 23 (43%) also undergoing local therapy.SBRT and RFA were the most common modalities employed.Most patients received local therapy at the first progression (39%) according to the timing of use.Patients receiving tebentafusp and local treatment demonstrated an improved OS at two years (HR=0.49)(p=0.02).Using the Wilcoxon Mann Whitney test, a median comparison analysis was performed for patients using local therapies and tebentafusp, versus tebentafusp alone, the median survival of the first group (local and tebentafusp) was 442 days, while for the second group, it was 315 days, (z= -2.360) (p=0.018).There was no association between the benefit of OS and the baseline characteristics analyzed.Conclusions: Our study has shown that patients who receive tebentafusp and local therapy have a 51% lower chance of death compared to those who only receive tebentafusp.Prospective studies are warranted to validate these findings and optimize treatment strategies for this challenging disease.