Regorafenib combined with PD1 blockade increases CD8 T-cell infiltration by inducing CXCL10 expression in hepatocellular carcinoma

Abstract

Background and purposeCombining inhibitors of vascular endothelial growth factor and the programmed cell death protein 1 (PD1) pathway has shown efficacy in multiple cancers, but the disease-specific and agent-specific mechanisms of benefit remain unclear. We examined the efficacy and defined the mechanisms of benefit when combining regorafenib (a multikinase antivascular endothelial growth factor receptor inhibitor) with PD1 blockade in murine hepatocellular carcinoma (HCC) models.Basic proceduresWe used orthotopic models of HCC in mice with liver damage to test the effects of regorafenib—dosed orally at 5, 10 or 20 mg/kg daily—combined with anti-PD1 antibodies (10 mg/kg intraperitoneally thrice weekly). We evaluated the effects of therapy on tumor vasculature and immune microenvironment using immunofluorescence, flow cytometry, RNA-sequencing, ELISA and pharmacokinetic/pharmacodynamic studies in mice and in tissue and blood samples from patients with cancer.Main findingsRegorafenib/anti-PD1 combination therapy increased survival compared with regofarenib or anti-PD1 alone in a regorafenib dose-dependent manner. Combination therapy increased regorafenib uptake into the tumor tissues by normalizing the HCC vasculature and increasing CD8 T-cell infiltration and activation at an intermediate regorafenib dose. The efficacy of regorafenib/anti-PD1 therapy was compromised in mice lacking functional T cells (Rag1-deficient mice). Regorafenib treatment increased the transcription and protein expression of CXCL10—a ligand for CXCR3 expressed on tumor-infiltrating lymphocytes—in murine HCC and in blood of patients with HCC. Using Cxcr3-deficient mice, we demonstrate that CXCR3 mediated the increased intratumoral CD8 T-cell infiltration and the added survival benefit when regorafenib was combined with anti-PD1 therapy.Principal conclusionsJudicious regorafenib/anti-PD1 combination therapy can inhibit tumor growth and increase survival by normalizing tumor vasculature and increasing intratumoral CXCR3+CD8 T-cell infiltration through elevated CXCL10 expression in HCC cells.

Regorafenib Combined with Other Systemic Therapies: Exploring Promising Therapeutic Combinations in HCC

“…39 As such, regorafenib's broad spectrum of kinase inhibition, together with its immunomodulatory effects, may explain its established and emerging clinical activity in various tumor types and have offered a rationale for supporting clinical trials to investigate the development of a combination strategy with immune checkpoint inhibitors. [40][41][42] Regorafenib is metabolized by UGT1A9 and CYP3A4 enzymes to two active metabolites M-5 (demethylated N-oxide) and M-2 (N-oxide). 43 CYP enzymes may be inhibited or induced by the coadministration of agents that interact with the same enzymes.…”

“…Of note, recent studies have also shown that antitumor immune responses and vascular normalization can be reciprocally regulated by CD4+ T effector cells in other cancers. 40,[77][78][79][80][81] In HCC, dual VEGFR-2/PD1 blockade using antibodies has recently been shown to normalize tumor vasculature and induce antitumor immunity in a preclinical animal model with underlying liver damage. 82 The use of combination therapy with anti-VEGF (bevacizumab) and anti-PD-L1 (atezolizumab) monoclonal antibodies has been shown to significantly increase survival compared with sorafenib in the randomized phase III IMBRAVE150 study.…”

“…In a preclinical study, it has been reported that in a combination treatment with anti-PD-1 antibody, regorafenib can significantly enhance PD1 blockade effects in a dose-dependent manner in HCC models. 40 The benefit was due to the activity of the two agents on both normalizations of the HCC vasculature and stimulation of anti-tumor immunity. The combination treatment inhibited STAT3 activity and increased the expression of the chemokine CXCL10, which increased both tumor penetration and survival of activated CD8 T cells.…”

“…As such, regorafenib’s broad spectrum of kinase inhibition, together with its immunomodulatory effects, may explain its established and emerging clinical activity in various tumor types and have offered a rationale for supporting clinical trials to investigate the development of a combination strategy with immune checkpoint inhibitors. 40–42 …”

“…Of note, recent studies have also shown that antitumor immune responses and vascular normalization can be reciprocally regulated by CD4+ T effector cells in other cancers. 40 , 77–81 …”