Supplementary Material for: Incidence of Hyper Progressive Disease in Combination Immunotherapy and Anti-Programmed Cell Death Protein 1/Programmed Death-Ligand 1 Monotherapy for Unresectable Hepatocellular Carcinoma

Introduction: Programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) signaling blockade is the most effective strategy for the treatment of immune evading hepatocellular carcinoma (HCC). While immune checkpoint inhibitor has revolutionized the concept of cancer treatment, it has also led to unexpected tumor growth. Regulatory T cells express PD-1 and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) receptors, which are proliferated and activated by antibody binding, and their ratio to CD8+ T cells is altered, which is one of the causes for hyper progressive disease (HPD). We examined the frequency of HPD in anti-PD-1/PD-L1 monotherapy and combination therapy with vascular endothelial growth factor (VEGF) antibody and anti-CTLA-4 antibodies. Methods: This was a prospective and retrospective cohort study which enrolled 198 patients with unresectable HCC from January 2015 to December 2021 at the Kindai University Hospital. Fifty-eight patients received anti-PD-1/PD-L1 monotherapy, 119 patients combination with VEGF antibody, and 21 patients combination with anti-CTLA-4 antibody. We defined HPD as tumor growth rate (TGR) ratio ≥4, ΔTGR ≥40%, and tumor growth kinetics ratio ≥4. Results: The HPD rate was 10.3% (6/58) in anti-PD-1/PD-L1 monotherapy, 1.7% (2/119) in combination with VEGF antibody, and 4.8% (1/21) in combination with anti-CTLA-4 antibody (p = 0.034). The odds ratio for HPD in the combined anti-CTLA-4 antibody group was 0.433 (95% confidence interval [CI]: 0.05–3.83) when compared to the anti-PD-1/PD-L1 monotherapy group and 2.93 (95% CI: 0.25–33.79) when compared to the combined VEGF antibody group. Conclusion: The frequency of HPD in unresectable HCC compared to anti-PD-1/PD-L1 monotherapy was decreased with the combination with anti-VEGF antibody and not increased with anti-CTLA-4 antibody. Anti-PD-1/PD-L1 combined with anti-CTLA-4 antibody is now available in real-world and needs to be further validated with accumulated clinical practice.