# Focal adhesion kinase inhibition enhances response to checkpoint immunotherapy in hepatocellular carcinoma

## TL;DR

Inhibiting focal adhesion kinase improves the effectiveness of immunotherapy in liver cancer by boosting immune cell activity and reducing tumor-promoting factors.

## Contribution

FAK inhibition is shown to enhance anti-PD-1 immunotherapy in hepatocellular carcinoma through immune microenvironment reprogramming.

## Key findings

- FAK is highly expressed in HCC and linked to poor patient outcomes and immunosuppressive tumor environments.
- Pharmacologic FAK inhibition reduced fibrosis, angiogenesis, and enhanced CD8+ T cell function in mouse models.
- Combining FAK inhibition with anti-PD-1 therapy led to significant tumor regression in HCC models.

## Abstract

Despite the remarkable efficacy of immune checkpoint inhibitors (ICIs) in cancer therapy, their clinical benefit in hepatocellular carcinoma (HCC) remains limited. Focal adhesion kinase (FAK) plays a pivotal oncogenic role in various tumors by promoting angiogenesis, tumor proliferation, and immunosuppression. Therefore, targeting FAK represents a promising strategy to enhance immunotherapy outcomes in HCC.

We analyzed RNA-sequencing data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) to compare PTK2 (encoding FAK) expression between HCC tumors and adjacent normal tissues. Associations between PTK2 expression levels and clinicopathological features were systematically evaluated. Immune cell infiltration landscapes were characterized using CIBERSORT and ssGSEA algorithms, while the Tumor Immune Dysfunction and Exclusion (TIDE) computational framework was applied to predict HCC responsiveness to ICIs based on PTK2 expression. To experimentally validate therapeutic efficacy, we established orthotopic liver cancer models by transposon-mediated integration of Myc and KrasG12D oncogenes into hepatocytes of Trp53 null/null mice (pTMK/Trp53-/-), coupled with subcutaneous xenograft models. These models were treated with FAK inhibitor IN10018 as monotherapy or in combination with anti-PD-1 immunotherapy.

FAK was highly expressed and frequently amplified in HCC tumors, which predicted worse pathological features of patients. A notable feature of FAK-positive HCC tumors was an adverse immune microenvironment marked by a depletion of CD8+ cytotoxic T cells and an abundance of suppressive myeloid cells. Pharmacologic FAK inhibition demonstrated efficacy against primary liver cancer (PLC) tumors in both orthotopic and subcutaneous mouse models and was associated with progressive reduction in fibrosis and angiogenesis and stimulation of cytotoxic CD8+ T cell function. Synergy with anti-PD-1 blockade substantially reprogrammed the immune microenvironment, leading to tumor regression, compared to current therapeutic strategies for HCC.

FAK inhibitors can enhance the sensitivity of HCC to anti-PD-1 therapy by inhibiting angiogenesis and fibrosis and promoting CD8+ T cell infiltration. This effect exceeds the efficacy of the current first-line treatment, highlighting FAK inhibition as a novel and promising therapeutic strategy for HCC.