Liver Metastases are Associated with a Short Post-Progression Survival in a Real-World Group of Patients with Melanoma Treated with Checkpoint Inhibitors.

Introduction: The introduction of immunotherapy (IT) has transformed clinical care of patients with metastatic melanoma. However, many patients still die as a result of progressive disease. Here we analyzed how IT improved survival in a real-world setting. Additionally, we investigated whether IT alters the dynamics and pattern of metastatic progression in different organs resulting from tissue-specific immune microenvironments.

Methods: We retrospectively compared a group of 61 patients with metastatic melanoma (24 female, 37 male) treated with IT between 2015 and 2018 with a historical control group of 56 patients with metastatic melanoma (21 female, 35 male) treated with chemotherapy between 2005 and 2008 regarding treatment response rates and overall survival as well as the timing and distribution of metastatic progression.

Results: Patients with metastatic melanoma treated with IT showed increased response rates and longer overall survival when compared with patients treated with chemotherapy. In addition, treatment with IT altered the dynamics but not the pattern of metastatic progression when compared with treatment with chemotherapy. Interestingly, patients receiving IT lived significantly longer after metastatic progression to lymph nodes, lungs and brain, but not after metastatic progression to the liver.

Conclusion: Our results confirm the efficacy of IT in a real-world setting. The altered dynamics of metastases supports studies suggesting a unique role of immune privilege in the liver tissue microenvironment that increases resistance to immunotherapy.