Chemokines in CAR-T Applications
October 30th, 2025
Introduction
CAR-T therapies for hematological malignancies have shown promising results for CD19 and BCMA (B-Cell maturation antigen) targeted therapies. However, CAR-T therapy for solid tumors has been less promising due to several obstacles created by the tumor microenvironment, specifically the involvement of regulatory T cells (T-regs), myeloid derived suppressor cells (MDSCs), tumor associated macrophages and inhibitory cytokines such as IL-10 and TGFβ.
Immune checkpoint inhibitors have also been of great interest in developing antibodies against these immune modulators such as PD-1 (Programmed Cell Death-1) receptor. The PD-1/PD-L1 axis functions to promote T cell exhaustion and anergy, induce apoptosis, stimulate regulatory T cell function and regulate immunosuppression. As PD-1 is found on activated T cells and B cells, and its ligand PD-L1 and PD-L2 have been found to be expressed on tumor cells and MDSCs in liver metastasis murine tumor models, cancer cells can directly inhibit the activation of T cells involved in the antitumor response, blocking T cell activation and IL-2 production. Therapies that block the PD-1/PD-L1 axis have found that blocking this interaction facilitates the activation of T cells their anti-tumor properties.
Chemokines are an integral part of supporting the tumor microenvironment since they are essential for homing immune cells in specific tissue microenvironment (Letourneur). Chemokines are also involved in T cell regulation that affects cancer progression. Chemokines such as CCL22, CCL17 and CCL18 are involved in recruiting regulatory T cells to the tumor, promoting an immunosuppressive environment, helping the tumor escape detection by the immune system (Letourneur). Furthermore, the tumor microenvironment is sustained by CXCL4 producing cancer cells, which upregulate PD-1 expression on CXCR3+ CTLs (Deng). CXCR3 has been found to upregulate PD-L1 expression in gastric cancer cells (Zhang), promoting the tumor microenvironment.
Furthermore, mouse knockout models used by Deng et al demonstrated a negative immune regulatory function for CXCL4 through CXCR2, which can be hijacked by cancer cells to evade the host immune system, in a colorectal cancer model. Specifically CXCL4-/- knockout mice demonstrated increased tumor growth, decreased CTL proliferation and IFN-γ production, while increasing Treg proliferation and TGF-β production but downregulating PD-1 expression in T-regs, making them more resistant to apoptosis and anergy. Plasma IFN-γ production was measured by ELISA, while CTL proliferation was measured by the CFSE assay (Deng)
Chemokine activity can be measured in various ways. Various cell lines have been created to study the roles that cytokines play in different cancer disease models. Subat et al created a Hepatocellular Carcinoma (HCC) cell line treated with a DNA demethylating agent, 5-aza-2’-deoxycytidine to characterize genes inactivated by DNA methylation in HCC. It was demonstrated that CXCL2 was downregulated in tumor tissue and upregulated in DAC treated cell lines. Biomarkers such as PD-1 and PD-L1 are typically characterized and measured through flow cytometry.
Immune checkpoint inhibitors have also been of great interest in developing antibodies against these immune modulators such as PD-1 (Programmed Cell Death-1) receptor. The PD-1/PD-L1 axis functions to promote T cell exhaustion and anergy, induce apoptosis, stimulate regulatory T cell function and regulate immunosuppression. As PD-1 is found on activated T cells and B cells, and its ligand PD-L1 and PD-L2 have been found to be expressed on tumor cells and MDSCs in liver metastasis murine tumor models, cancer cells can directly inhibit the activation of T cells involved in the antitumor response, blocking T cell activation and IL-2 production. Therapies that block the PD-1/PD-L1 axis have found that blocking this interaction facilitates the activation of T cells their anti-tumor properties.
Chemokines are an integral part of supporting the tumor microenvironment since they are essential for homing immune cells in specific tissue microenvironment (Letourneur). Chemokines are also involved in T cell regulation that affects cancer progression. Chemokines such as CCL22, CCL17 and CCL18 are involved in recruiting regulatory T cells to the tumor, promoting an immunosuppressive environment, helping the tumor escape detection by the immune system (Letourneur). Furthermore, the tumor microenvironment is sustained by CXCL4 producing cancer cells, which upregulate PD-1 expression on CXCR3+ CTLs (Deng). CXCR3 has been found to upregulate PD-L1 expression in gastric cancer cells (Zhang), promoting the tumor microenvironment.
Furthermore, mouse knockout models used by Deng et al demonstrated a negative immune regulatory function for CXCL4 through CXCR2, which can be hijacked by cancer cells to evade the host immune system, in a colorectal cancer model. Specifically CXCL4-/- knockout mice demonstrated increased tumor growth, decreased CTL proliferation and IFN-γ production, while increasing Treg proliferation and TGF-β production but downregulating PD-1 expression in T-regs, making them more resistant to apoptosis and anergy. Plasma IFN-γ production was measured by ELISA, while CTL proliferation was measured by the CFSE assay (Deng)
Chemokine activity can be measured in various ways. Various cell lines have been created to study the roles that cytokines play in different cancer disease models. Subat et al created a Hepatocellular Carcinoma (HCC) cell line treated with a DNA demethylating agent, 5-aza-2’-deoxycytidine to characterize genes inactivated by DNA methylation in HCC. It was demonstrated that CXCL2 was downregulated in tumor tissue and upregulated in DAC treated cell lines. Biomarkers such as PD-1 and PD-L1 are typically characterized and measured through flow cytometry.
References
1. D. Letourneur, F.X. Danlos, A. Marabelle. Chemokine Biology on immune checkpoint-targeted therapies. European Journal of Cancer, 137(2020) pp.260-271
2. S. Subat, K. Mogushi, M. Yasen, T. Kohda, Y. Ishikawa, H. Tanaka. Identification of genes and pathways, including the CXCL2 axis, altered by DNA methylation in hepatocellular carcinoma. J Canc Res Clin Oncol, 145 (2019), pp. 675-684
3. S. Deng, Q. Deng, Y. Zhang, H. Ye, X. Yu, Y. Zhang, et al. Non-platelet-derived CXCL4 differentially regulates cytotoxic and regulatory T cells through CXCR3 to suppress the immune response to colon cancer. Canc Lett, 443 (2019), pp. 1-12
4. C. Zhang, Z. Li, L. Xu, X. Che, T. Wen, Y. Fan, et al. CXCL9/10/11, a regulator of PD-L1 expression in gastric cancer. BMC Canc, 18 (2018)
2. S. Subat, K. Mogushi, M. Yasen, T. Kohda, Y. Ishikawa, H. Tanaka. Identification of genes and pathways, including the CXCL2 axis, altered by DNA methylation in hepatocellular carcinoma. J Canc Res Clin Oncol, 145 (2019), pp. 675-684
3. S. Deng, Q. Deng, Y. Zhang, H. Ye, X. Yu, Y. Zhang, et al. Non-platelet-derived CXCL4 differentially regulates cytotoxic and regulatory T cells through CXCR3 to suppress the immune response to colon cancer. Canc Lett, 443 (2019), pp. 1-12
4. C. Zhang, Z. Li, L. Xu, X. Che, T. Wen, Y. Fan, et al. CXCL9/10/11, a regulator of PD-L1 expression in gastric cancer. BMC Canc, 18 (2018)
Related Products
Biotin-CXCL12 (SDF-1α)
$134.00 - $9,756.40
Stromal-Cell Derived Factor-1α (SDF-1α) (CXCL12) attracts lymphocytes and plays important roles in embryogenesis and angiogenesis with implications in tumor metastasis. By binding to CXCR4, one of the co-receptors for HIV viral entry, SDF-1α can suppress HIV. Besides CXCR4, SDF-1 α also binds to the “decoy” receptor CXCR7, and activates the downstream β-arrestin- rather than G protein-mediated signaling pathway.
