title: PD-L1 expression in metastatic neuroblastoma as an additional mechanism for limiting immune surveillance.
abstract: The prognosis of high-risk neuroblastoma (NB) remains poor, although immunotherapies with anti-GD2 antibodies have been reported to provide some benefit. Immunotherapies can be associated with an IFNγ storm that induces in tumor cells the "adaptive immune resistance" characterized by thede-novoexpression of Programmed Death Ligands (PD-Ls). Tumor cells can also constitutively express PD-Ls in response to oncogenic signaling. Here, we analyze the constitutive and the inducible surface expression of PD-Ls in NB cells. We show that virtually all HLA class IposNB cell lines constitutively express PD-L1, whereas PD-L2 is rarely detected. IFNγ upregulates or induces PD-L1 both in NB cell linesin vitroand in NB engrafted nude/nude mice. Importantly, after IFNγ stimulation PD-L1 can be acquired by NB cell lines, as well as by metastatic neuroblasts isolated from bone marrow aspirates of high-risk NB patients, characterized by differentMYCNamplification status. Interestingly, in one patient NB cells were poorly responsive to IFNγ stimulation, pointing out that responsiveness to IFNγ might represent a further element of heterogeneity in metastatic neuroblasts. Finally, we document the presence of lymphocytes expressing the PD-1 receptor in NB-infiltrated bone marrow of patients. PD-1poscells are mainly represented by αβ T cells, but also include small populations of γδ T cells and NK cells. Moreover, PD-1posT cells have a higher expression of activation markers. Overall, our data show that a PD-L1-mediated immune resistance mechanism occurs in metastatic neuroblasts and provide a biological rationale for blocking the PD-1/PD-Ls axis in future combined immunotherapeutic approaches.
authors.affiliation: Dipartimento di Medicina Sperimentale, Università degli Studi di Genova , Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Dondero
authors.affiliation: Istituto Giannina Gaslini, Laboratorio di Oncologia , Genova, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Pastorino
authors.affiliation: Dipartimento di Medicina Sperimentale, Università degli Studi di Genova , Italy.
authors.forename: Mariella
authors.initials: M
authors.lastname: Della Chiesa
authors.affiliation: Istituto Giannina Gaslini, Laboratorio di Oncologia , Genova, Italy.
authors.forename: Maria Valeria
authors.initials: MV
authors.lastname: Corrias
authors.affiliation: Istituto Giannina Gaslini, Laboratorio di Oncologia , Genova, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Morandi
authors.affiliation: Istituto Giannina Gaslini, Laboratorio di Oncologia , Genova, Italy.
authors.forename: Vito
authors.initials: V
authors.lastname: Pistoia
authors.affiliation: CRCM, Team Immunity and Cancer, Inserm, Institut Paoli-Calmettes, Aix-Marseille Université, CNRS , UM 105, U1068, UMR7258 , Marseille, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Olive
authors.affiliation: Dipartimento di Medicina Sperimentale, Università degli Studi di Genova , Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bellora
authors.affiliation: Università di Pavia and Dipartimento di Onco-Ematologia Pediatrica, Ospedale Bambino Gesù , Roma, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Locatelli
authors.affiliation: Università di Pavia and Dipartimento di Onco-Ematologia Pediatrica, Ospedale Bambino Gesù , Roma, Italy.
authors.forename: Aurora
authors.initials: A
authors.lastname: Castellano
authors.affiliation: Istituto Giannina Gaslini, Laboratorio di Oncologia , Genova, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Moretta
authors.affiliation: Dipartimento di Medicina Sperimentale, Università degli Studi di Genova, Italy; Centro di Eccellenza per le Ricerche Biomediche, Università degli Studi di Genova, Viale Benedetto XV, Genova, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Moretta
authors.affiliation: Dipartimento di Medicina Sperimentale, Università degli Studi di Genova, Italy; Istituto Giannina Gaslini, Laboratorio di Oncologia, Genova, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Bottino
authors.affiliation: Dipartimento di Medicina Sperimentale, Università degli Studi di Genova, Italy; Centro di Eccellenza per le Ricerche Biomediche, Università degli Studi di Genova, Viale Benedetto XV, Genova, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Castriconi
keywords: Anti-tumor immunity; INF-γ; PD-1; PD-L1; PD-L2; T cells; TNF-α; immune checkpoints; natural killer cells; neuroblastoma