Clinical, FDG-PET and molecular markers of immune checkpoint inhibitor response in patients with metastatic Merkel cell carcinoma

摘要: Background Metastatic Merkel cell carcinoma (mMCC) is an aggressive neuroendocrine malignancy of the skin with a poor prognosis. Immune checkpoint inhibitors (ICIs) have shown substantial efficacy and favorable safety in clinical trials. Methods Medical records patients (pts) mMCC treated ICIs from August 2015 to December 2018 at Peter MacCallum Cancer Centre Australia were analyzed. Response was assessed serial imaging, majority FDG-PET/CT scans. RNA sequencing immunohistochemistry for PD-L1, CD3 polyomavirus (MCPyV) on tumor samples performed. Results 23 pts ICIs. A median 8 cycles (range 1 47) administered, treatment ongoing 6 pts. Objective responses (OR) observed 14 (61%): 10 (44%) complete (CR) 4 (17%) partial (PR). Median time response weeks 12) 12-month progression-free survival rate 39%. Increased OR seen aged less than 75 (OR 80% vs 46%), no prior history chemotherapy 64% 50%), immune-related adverse event 100% 43%) MCPyV-negative tumors 69% 43%). Pts CR had lower mean metabolic volume baseline scan (CR: 35.7 mL, CR: 187.8 p=0.05). There correlation between PD-L1 positivity MCPyV status (p=0.764) or (p=0.245). received radiation therapy (RT) during ICI: started RT concurrently 75%, 3 isolated ICI-resistant lesions successfully multisite progression continued progress despite RT. Overall, (26%) grade 1–2 events. Conclusion showed consistent trial data. Clinical imaging predictors identified.