Optimizing the Safe Washout Period for Liver Transplantation Following Immune Checkpoint Inhibitors with Atezolizumab, Nivolumab, or Pembrolizumab

Abstract

Using immune checkpoint inhibitors (ICIs) as a downstaging therapy for liver transplantation (LT) has improved outcomes for patients with advanced hepatocellular carcinoma (HCC). However, this therapy carries a risk of post-transplant graft rejection. The washout (WO) period between the last ICI dose and LT seems critical in preventing postoperative rejection. This study aimed to optimize the WO period by balancing tumor burden suppression and rejection prevention using ICIs before LT. We reviewed published case reports or series from March 2020 to December 2022 regarding LT for HCC after downstaging or bridge therapy with ICIs and included 4 of our cases. Most patients received atezolizumab, nivolumab, or pembrolizumab; these ICIs shared a half-life of around 28 days. Therefore, we excluded cases without definite WO period data and those using non-atezolizumab/nivolumab/pembrolizumab ICIs and ultimately enrolled 22 patients for analysis. We compared their clinical outcomes and estimated the rejection-free survival for every 0.5 half-life interval. Most study subjects received nivolumab (n=25). Six patients had severe rejections (nivolumab group, n=5) and needed rescue management. Of the 6 cases, 1 patient died after rejection, and 2 underwent re-transplantation. The median WO period in these 6 patients was 22 days (IQR: 9-35 days). In addition, we found that a 1.5 half-life (42 days) was the shortest safe WO period associated with significant rejection-free survival (P=.005). Our results showed that 42 days was the safest WO period before LT for HCC after ICI with atezolizumab, nivolumab, or pembrolizumab.