Neuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor in childhood, causing 15 % of cancer mortality. We recently demonstrated that cell surface nucleolin (NCL) represents a novel cellular target for preclinical therapy against NB cell lines.

NB cells derived from i) infiltrated bone marrow (BM; 132 patients, 85 at onset, 47 relapsed/refractory); ii) NB tumor tissues from 11 relapsed/refractory NB patients; iii) murine generations of 9 patient-derived xenografts (PDX) were evaluated for cell surface NCL expression by flow cytometry and immunohistochemistry analyses. The antitumor efficacy of a liposomal formulation of doxorubicin (DXR) functionalized with the F3 peptide-recognizing NCL (F3-lipo[DXR]) was tested towards patient-derived multicellular tumor spheroids (MCTS) and PDX models of NB.

About 60 % of BM-infiltrating NB cells and NB cells derived from tumor biopsies, and about 80 % of NB cells derived from PDX expressed cell surface NCL. In vitro, F3-lipo[DXR] resulted significantly more effective in terms of reducing cell viability of all the patient-derived MCTS models used, compared to the untargeted liposomal formulation (lipo[DXR]). In the in vivo PDX models, F3-lipo[DXR] significantly delayed tumor growth, induced tumor cells apoptosis and partly reduced the tumor vasculature. Furthermore, in a PDX model harboring the ALK mutation p.F1174L, the administration of the anti-ALK inhibitor crizotinib significantly increased the antitumor efficacy of F3-lipo[DXR].

Our results confirm that cell surface NCL is a biomarker and a potential target for NB, paving the way for further investigations aimed at the future clinical translation of innovative combination strategies against NB.