Tumor-derived GDF-15 blocks LFA-1 dependent T cell recruitment and suppresses responses to anti-PD-1 treatment

Immune checkpoint blockade therapy is beneficial and even curative for some cancer patients. However, the majority don't respond to immune therapy. Across different tumor types, pre-existing T cell infiltrates predict response to checkpoint-based immunotherapy. Based on in vitro pharmacological studies, mouse models and analyses of human melanoma patients, we show that the cytokine GDF-15 impairs LFA-1/β2-integrin-mediated adhesion of T cells to activated endothelial cells, which is a pre-requisite of T cell extravasation. In melanoma patients, GDF-15 serum levels strongly correlate with failure of PD-1-based immune checkpoint blockade therapy. Neutralization of GDF-15 improves both T cell trafficking and therapy efficiency in murine tumor models. Thus GDF-15, beside its known role in cancer-related anorexia and cachexia, emerges as a regulator of T cell extravasation into the tumor microenvironment, which provides an even stronger rationale for therapeutic anti-GDF-15 antibody development.

Abstract 6118: Tumor-derived GDF-15 promotes immune escape of tumors by functional alteration of the myeloid compartment

Background: Growth and differentiation factor 15 (GDF-15), a divergent member of the TGF-β protein superfamily, shows low physiological baseline expression. GDF-15 is, however, strongly upregulated during pregnancy. It is further induced in stressed and damaged tissues, where it limits immune infiltration and inflammation. In solid tumors, GDF-15 was shown to be a key inhibitor of T-cell infiltration. While this might already explain the strong correlation between GDF-15 overexpression and poor survival with or without checkpoint-based immunotherapy, effects of GDF-15 on dendritic cells and monocytes may further shape the tumor microenvironment.

Methods: To analyze the impact of GDF-15 in murine tumor models, GDF-15 was either deleted by CRISPR/CAS9 gene editing or neutralized by administration of a blocking antibody. Effects on tumor growth were recorded and the composition of the tumor microenvironment was characterized by flow cytometry. More detailed insight into tumor-immune interactions was obtained via the CrownBio Mouse I/O RNA-Seq Panel. Specific effects on polarization of innate and on antigen-specific priming of adaptive immune cells were confirmed in cellular assays in vitro.

Results: Tumor-derived GDF-15 modulates the tumor microenvironment by inhibiting infiltration and activation of myeloid cells. GDF-15 thereby impairs the induction of antitumoral immune responses. Deletion of GDF-15 enhances infiltration of innate cells into immune-excluded tumors, supports the priming of naïve T cells by dendritic cells and generates a pro-inflammatory tumor microenvironment. In vitro, GDF-15 inhibits DC maturation and synapse formation, thus preventing successful T-cell activation. Moreover, GDF-15 interferes with M1 polarization of macrophages.

Conclusion: GDF-15 secretion helps tumors to generate a microenvironment that is poorly infiltrated by immune cells. GDF-15 further polarizes myeloid cells towards a tumor-promoting, anti-inflammatory phenotype. By inducing a more pro-inflammatory tumor phenotype, anti-GDF-15 antibodies may synergize with other immunotherapeutic agents. A clinical trial combining anti-GDF-15 (CTL002) with anti-PD-1 (NCT04725474) is ongoing.

Citation Format: Markus Haake, Beatrice Haack, Sabrina Genßler, Julia Weigandt, Marlene Auer, Vincent Thiemann, Wahid M. Haq, Melanie Haag, Florian Wedekink, Birgitt Fischer, Kathrin Klar, Matthias Wölfl, Christine Schuberth-Wagner, Jorg Wischhusen. Tumor-derived GDF-15 promotes immune escape of tumors by functional alteration of the myeloid compartment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6118.

Periodic changes in blood flow in the in vivo rat kidney

The frequency response of the blood flow through the rat kidney in vivo has been studied. A piston controlled by a random-signal generator compressed the abdominal aorta proximal to the renal artery eliciting stochastical arterial pressure changes of an amplitude of less than or equal to 5 mm Hg. This small amplitude allowed to study the system under physiological conditions. In accord with earlier results from isolated kidneys pressure induced maxima of flow resistance were found at 0.005 Hz and at 0.1 Hz, thus demonstrating that in vivo humoral and/or nervous factors do not significantly alter the renal vascular response to changes of arterial pressure.