Poly(I:C) primes primary human glioblastoma cells for an immune response invigorated by PD-L1 blockade

Jorrit De Waele; Elly Marcq; Jonas Rm Van Audenaerde; Jinthe Van Loenhout; Christophe Deben; Karen Zwaenepoel; Erik Van de Kelft; David Van der Planken; Tomas Menovsky; Johan Mj Van den Bergh; Yannick Willemen; Patrick Pauwels; Zwi N Berneman; Filip Lardon; Marc Peeters; An Wouters; Evelien Lj Smits

doi:10.1080/2162402X.2017.1407899

Poly(I:C) primes primary human glioblastoma cells for an immune response invigorated by PD-L1 blockade

Oncoimmunology. 2017 Dec 12;7(3):e1407899. doi: 10.1080/2162402X.2017.1407899. eCollection 2018.

Authors

Jorrit De Waele¹, Elly Marcq¹, Jonas Rm Van Audenaerde¹, Jinthe Van Loenhout¹, Christophe Deben¹, Karen Zwaenepoel², Erik Van de Kelft³, David Van der Planken³, Tomas Menovsky⁴, Johan Mj Van den Bergh⁵, Yannick Willemen⁵, Patrick Pauwels^{1

2}, Zwi N Berneman^{5

6}, Filip Lardon¹, Marc Peeters^{1

7}, An Wouters¹, Evelien Lj Smits^{1

5}

Affiliations

¹ Center for Oncological Research, University of Antwerp, Wilrijk, Antwerp, Belgium.
² Department of Pathology, Antwerp University Hospital, Edegem, Antwerp, Belgium.
³ Department of Neurosurgery, AZ Nikolaas, Sint-Niklaas, East Flanders, Belgium.
⁴ Department of Neurosurgery, Antwerp University Hospital, Edegem, Antwerp, Belgium.
⁵ Laboratory of Experimental Hematology, University of Antwerp, Wilrijk, Antwerp, Belgium.
⁶ Department of Hematology, Antwerp University Hospital, Edegem, Antwerp, Belgium.
⁷ Department of Oncology, Multidisciplinary Oncological Center Antwerp, Antwerp University Hospital, Antwerp, Edegem, Belgium.

Abstract

Prognosis of glioblastoma remains dismal, underscoring the need for novel therapies. Immunotherapy is generating promising results, but requires combination strategies to unlock its full potential. We investigated the immunomodulatory capacities of poly(I:C) on primary human glioblastoma cells and its combinatorial potential with programmed death ligand (PD-L) blockade. In our experiments, poly(I:C) stimulated expression of both PD-L1 and PD-L2 on glioblastoma cells, and a pro-inflammatory secretome, including type I interferons (IFN) and chemokines CXCL9, CXCL10, CCL4 and CCL5. IFN-β was partially responsible for the elevated PD-1 ligand expression on these cells. Moreover, real-time PCR and chloroquine-mediated blocking experiments indicated that poly(I:C) triggered Toll-like receptor 3 to elicit its effect. Cocultures of poly(I:C)-treated glioblastoma cells with peripheral blood mononuclear cells enhanced lymphocytic activation (CD69, IFN-γ) and cytotoxic capacity (CD107a, granzyme B). Additional PD-L1 blockade further propagated immune activation. Besides activating immunity, poly(I:C)-treated glioblastoma cells also doubled the attraction of CD8⁺ T cells, and to a lesser extent CD4⁺ T cells, via a mechanism which included CXCR3 and CCR5 ligands. Our results indicate that by triggering glioblastoma cells, poly(I:C) primes the tumor microenvironment for an immune response. Secreted cytokines allow for immune activation while chemokines attract CD8⁺ T cells to the front, which are postulated as a prerequisite for effective PD-1/PD-L1 blockade. Accordingly, additional blockade of the concurrently elevated tumoral PD-L1 further reinforces the immune activation. In conclusion, our data proposes poly(I:C) treatment combined with PD-L1 blockade to invigorate the immune checkpoint inhibition response in glioblastoma.

Keywords: Toll-like receptor 3 (TLR3); brain tumor; cancer immunotherapy; glioblastoma (GBM); glioma; immune checkpoint blockade; poly(I:C); primary patient-derived cells; programmed death ligand 1 (PD-L1); programmed death ligand 2 (PD-L2).

Publication types

Research Support, Non-U.S. Gov't

Grants and funding

Research Foundation Flanders, 1523715N, Research Foundation Flanders, 1121016N, Research Foundation Flanders, 1S32316N, University Foundation of Belgium, University of Antwerp (Research fund), Multidisciplinary Oncological Center Antwerp (Antwerp University Hospital), Flanders Innovation & Entrepreneurship, 141433. This work was performed with support of the Research Foundation Flanders (grant number: 1523715N), the Research Fund of the University of Antwerp and the Multidisciplinary Onco-logical Center (MOCA) of the Antwerp University Hospital (UZA). J. De Waele and J. Van Audenaerde are research fellows of the Research Foundation Flanders (fellowship numbers: 1121016N and 1S32316N), E. Marcq of Flanders Innovation & Entrepreneurship (fellowship number: 141433). We also thank the Vereycken family, Mr. Willy Floren and the University Foundation of Belgium for their financial support.