# CAR-T triggers TAM reeducation and adaptive anti-tumor response via TREM2 deficiency or CD40 agonist

## TL;DR

This study shows that targeting TREM2 or using a CD40 agonist can improve CAR-T therapy effectiveness in liver cancer by reprogramming immune cells.

## Contribution

The study reveals that TREM2+ macrophages cause resistance to CAR-T therapy and that TREM2 deficiency or CD40 agonism can overcome this resistance.

## Key findings

- TREM2+ macrophages are critical for resistance to GPC3-CAR-T therapy in hepatocellular carcinoma.
- Trem2 deficiency reprograms tumor-associated macrophages and activates tumor-specific CD8+ T cells.
- CD40 agonism mimics the effects of Trem2 deficiency and enhances CAR-T efficacy.

## Abstract

Chimeric antigen receptor (CAR)-T therapy targeting GPC3 shows unsatisfactory clinical efficacy in hepatocellular carcinoma (HCC). Combining clinical data and the immunocompetent orthotopic HCC model, we demonstrate that TREM2+ tumor-associated macrophages (TAMs) are critical mediators of GPC3-CAR-T resistance. We find that Trem2 deficiency synergizes with GPC3-CAR-T to enhance tumor control by expanding endogenous tumor-specific CD8+ T cells (not CAR-T amplification) and reeducating TAMs to an anti-tumor CXCL9hi/SPP1lo phenotype via metabolic reprogramming. Mechanistically, this combination enhances oxidative metabolism while suppressing glycolysis through JAK-STAT1 triggering, AMPK activation, and PI3K-AKT-mTOR inhibition. Crucially, Trem2 deficiency up-regulates CD40 expression, enabling CD40 agonism to phenocopy Trem2-deficiency effects via AMPK activation and STAT1-driven CXCL9 production. Notably, the clinical agonist sotigalimab similarly enhances human CD8+ T cell migration in vitro. Our findings highlight the significance of combining GPC3-CAR-T therapy with CD40 agonist as a critical pre-requisite for eliciting reeducation of TAMs and enhancing the efficacy of CAR-T therapy in HCC.

•TREM2+ macrophages drive GPC3-CAR-T resistance in hepatocellular carcinoma•Trem2 deficiency reprograms TAM metabolism and activates tumor-specific CD8+ T cells•CD40 agonism mimics Trem2-KO via AMPK activation and STAT1-driven CXCL9 production•Sotigalimab enhances human CD8+ T cell migration in combination with CAR-T

TREM2+ macrophages drive GPC3-CAR-T resistance in hepatocellular carcinoma

Trem2 deficiency reprograms TAM metabolism and activates tumor-specific CD8+ T cells

CD40 agonism mimics Trem2-KO via AMPK activation and STAT1-driven CXCL9 production

Sotigalimab enhances human CD8+ T cell migration in combination with CAR-T

Ting Liu et al. show that TREM2+ macrophages drive resistance to GPC3-CAR-T therapy in hepatocellular carcinoma. Targeting TREM2—or using a CD40 agonist—overcomes resistance by triggering TAM reeducation and adaptive anti-tumor response, proposing a promising combination strategy to boost CAR-T efficacy.