CD47-SIRPα Checkpoint Inhibition Enhances Neutrophil-Mediated Killing of Dinutuximab-Opsonized Neuroblastoma Cells.

Paula Martínez-Sanz,Katka Franke,Hanke L Matlung,Karin Schornagel,Paul J J H Verkuijlen,Timo K Van Den Berg,Taco W Kuijpers,Robin Van Bruggen,Godelieve A M Tytgat,Arjan J Hoogendijk

doi:10.3390/cancers13174261

Abstract

Simple SummaryCurrent immunotherapy for high-risk neuroblastoma patients involves treatment with anti-GD2 antibody dinutuximab, which has significantly improved the survival rate. Still, approximately half of the patients succumb to the tumor; therefore, efforts to improve their prognosis are urgently needed. Since T cell targeting immune checkpoint inhibitors in neuroblastoma are limited due to the low immunogenicity of these tumors, alternative immunotherapeutic approaches should be studied. The therapeutic targeting of the innate immune checkpoint CD47-SIRPα has the ability to enhance antitumor effects of myeloid cells, especially in the presence of cancer-opsonizing antibodies. Given that neutrophil ADCC is a dominant effector mechanism leading to the eradication of dinutuximab-opsonized neuroblastoma cells, we have investigated the therapeutic potential of anti-GD2 antibody in combination with CD47-SIRPα inhibition. We demonstrate here that the capacity of neutrophils to kill dinutuximab-opsonized neuroblastoma cells is controlled by the CD47-SIRPα axis and its disruption promotes their cytotoxic potential even further, significantly improving dinutuximab responsiveness.High-risk neuroblastoma, especially after recurrence, still has a very low survival rate. Immune checkpoint inhibitors targeting T cells have shown remarkable clinical efficacy in adult solid tumors, but their effects in pediatric cancers have been limited so far. On the other hand, targeting myeloid immune checkpoints, such as CD47-SIPRα, provide the opportunity to enhance antitumor effects of myeloid cells, including that of neutrophils, especially in the presence of cancer-opsonizing antibodies. Disialoganglioside (GD2)-expressing neuroblastoma cells targeted with anti-GD2 antibody dinutuximab are in part eradicated by neutrophils, as they recognize and bind the antibody targeted tumor cells through their Fc receptors. Therapeutic targeting of the innate immune checkpoint CD47-SIRPα has been shown to promote the potential of neutrophils as cytotoxic cells in different solid tumor indications using different cancer-targeting antibodies. Here, we demonstrate that the capacity of neutrophils to kill dinutuximab-opsonized neuroblastoma cells is also controlled by the CD47-SIRPα axis and can be further enhanced by antagonizing CD47-SIRPα interactions. In particular, CD47-SIRPa checkpoint inhibition enhanced neutrophil-mediated ADCC of dinutuximab-opsonized adrenergic neuroblastoma cells, whereas mesenchymal neuroblastoma cells may evade immune recognition by a reduction of GD2 expression. These findings provide a rational basis for targeting CD47-SIRPα interactions to potentiate dinutuximab responsiveness in neuroblastomas with adrenergic phenotype.

Highlights

Immune checkpoint inhibitors of the adaptive immune system have in the last decades revolutionized the treatment landscape of cancer by demonstrating unprecedented success across a wide spectrum of adult advanced cancers [1]
Despite the progress seen with checkpoint blockade in adults, the use of such approaches in pediatric cancers has to date failed to show meaningful clinical efficacy [2,3]
In line with our data on CD47 KO neuroblastoma cells, we found the SIRPα blocking agent alone did not induce neutrophil-mediated cytotoxicity of tumor cells unopsonized with dinituximab

Summary

Introduction

Immune checkpoint inhibitors of the adaptive immune system have in the last decades revolutionized the treatment landscape of cancer by demonstrating unprecedented success across a wide spectrum of adult advanced cancers [1]. One major factor behind the pediatric tumor resistance to immune checkpoint immunotherapy is considered to be the low mutation rate that these tumors present [4,5,6]. This results in an important scarcity of neoantigens that can be recognized by T cells, giving rise to a lack of T cell-containing or so-called ‘cold tumors’. Patients with such tumors appear unable to benefit from T cell-directed checkpoint blockade therapies. The presence of M2 (pro-tumoral) macrophages and a dense stroma packed with fibroblasts is believed to prevent effective adaptive immune responses [2]

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Conclusion