Dataset Information

Anti-PD-1 in Combination With Trametinib Suppresses Tumor Growth and Improves Survival of Intrahepatic Cholangiocarcinoma in Mice.

ABSTRACT:

Background & aims

Intrahepatic cholangiocarcinoma (iCCA) accounts for a fraction of primary liver cancers but has a 5-year survival rate of only 10%. Immune checkpoint inhibitors are effective in treating many solid cancers, but immune checkpoint inhibitor monotherapy has no clear benefit in iCCA. Mitogen-activated kinase (MEK) inhibitors, such as trametinib, have shown promising results in preclinical studies for iCCA by inhibiting cell proliferation and modifying the tumor microenvironment. This study aimed to show the potential benefit of combining trametinib with anti-programmed cell death protein 1 (PD-1) therapy in different iCCA mouse models.

Methods

Here, we assessed the in vitro cytotoxicity of trametinib in mouse (SB1 and LD-1) and human (EGI-1) cholangiocarcinoma cell lines. We examined the efficacy of single-agent trametinib, anti-PD-1, and a combination of both in subcutaneous, orthotopic, and plasmid-induced iCCA mouse models. Flow cytometry analysis was used to elucidate changes in the tumor immune microenvironment upon treatment. Whole-exome sequencing (WES) was performed on the SB1 tumor cell line to correlate this preclinical model with iCCAs in patients.

Results

Trametinib reduced tumor cell growth of SB1, LD-1, and EGI-1 tumor cells in vitro. Trametinib treatment led to up-regulation of major histocompatibility complex (MHC-I) and programmed cell death ligand 1 (PD-L-1) (programmed cell death ligand 1) on tumor cells in vitro. The combination of trametinib and anti-PD-1 reduced tumor burden in several iCCA tumor models and improved survival in SB1 tumor-bearing mice compared with either agent alone. Immunoprofiling of tumor-bearing mice showed an increase of hepatic effector memory CD8⁺ and CD4⁺ T cells, as well as an increased degranulation of CD8⁺ T cells, indicating enhanced cytotoxicity. WES and somatic mutational analysis showed no mutations of KRAS, BRAF, and ERK in SB1 tumor cells, and showed a similar genetic signature of SB1 found in a cohort of patients with iCCA.

Conclusions

Altogether, our study shows that trametinib improves the immunogenicity of tumor cells by up-regulating MHC-I surface expression. The combination with anti-PD-1 results in optimal treatment efficacy for iCCA. WES of SB1 cells suggests that KRAS wild-type iCCAs also respond to this combination therapy.

SUBMITTER: Wabitsch S

PROVIDER: S-EPMC8413239 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Intrahepatic cholangiocarcinoma (ICC) is highly invasive and carries high mortality due to limited therapeutic strategies. In other solid tumors, immune checkpoint inhibitors (ICIs) target cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD1), and the PD1 ligand PD-L1 has revolutionized treatment and improved outcomes. However, the relationship and clinical significance of CTLA-4 and PD-L1 expression in ICC remains to be addressed. Deciphering CTLA-4 and PD-L1 interactions in ICC enable targeted therapy for this disease. In this study, immunohistochemistry (IHC) was used to detect and quantify CTLA-4, forkhead box protein P3 (FOXP3), and PD-L1 in samples from 290 patients with ICC. The prognostic capabilities of CTLA-4, FOXP3, and PD-L1 expression in ICC were investigated with the Kaplan-Meier method. Independent risk factors related to ICC survival and recurrence were assessed by the Cox proportional hazards models. Here, we identified that CTLA-4+ lymphocyte density was elevated in ICC tumors compared with peritumoral hepatic tissues (P <.001), and patients with a high density of CTLA-4+ tumor-infiltrating lymphocytes (TILsCTLA-4 High) showed a reduced overall survival (OS) rate and increased cumulative recurrence rate compared with patients with TILsCTLA-4 Low (P <.001 and P = .024, respectively). Similarly, patients with high FOXP3+ TILs (TILsFOXP3 High) had poorer prognoses than patients with low FOXP3+ TILs (P = .021, P = .034, respectively), and the density of CTLA-4+ TILs was positively correlated with FOXP3+ TILs (Pearson r = .31, P <.001). Furthermore, patients with high PD-L1 expression in tumors (TumorPD-L1 High) and/or TILsCTLA-4 High presented worse OS and a higher recurrence rate than patients with TILsCTLA-4 LowTumorPD-L1 Low. Moreover, multiple tumors, lymph node metastasis, and high TumorPD-L1/TILsCTLA-4 were independent risk factors of cumulative recurrence and OS for patients after ICC tumor resection. Furthermore, among ICC patients, those with hepatolithiasis had a higher expression of CTLA-4 and worse OS compared with patients with HBV infection or undefined risk factors (P = .018). In conclusion, CTLA-4 is increased in TILs in ICC and has an expression profile distinct from PD1/PD-L1. TumorPD-L1/TILsCTLA-4 is a predictive factor of OS and ICC recurrence, suggesting that combined therapy targeting PD1/PD-L1 and CTLA-4 may be useful in treating patients with ICC.