Near-infrared Photoimmunotherapy Targeting High-risk Human Neuroblastoma Cells Expressing GD2

Neuroblastoma (NB) is a primary malignant tumor of the peripheral sympathetic nervous system in infancy. Despite advances in treatment, the prognosis remains poor for high-risk NB patients. Although immunotherapy using anti-GD2 antibodies is available for high-risk NB, the therapeutic efficacy is insufficient. Near-infrared photoimmunotherapy (NIR-PIT) is an antitumor strategy that induces tumor-specific cytotoxicity by combining an antibody-photoabsorber conjugate (APC) with NIR light irradiation. In this study, we investigated the therapeutic efficacy of GD2-targeted NIR-PIT against human NB cells.

GD2 expression was analyzed on the surface of high-risk human NB cells (CHP-134, LA-N-5, IMR-32) and non-high-risk human NB cells (SK-N-SH) by flow cytometry. The APC was synthesized by incubating anti-GD2 antibody and IR700. The cytotoxic effect of GD2-targeted NIR-PIT was evaluated using the XTT assay. The distribution of dead cells within tumor spheres was evaluated using a live/dead assay. The in vivo antitumor effect of GD2-targeted NIR-PIT was assessed using a subcutaneous human NB xenograft tumor model.

GD2 protein was expressed on the surface of CHP-134, LA-N-5, and IMR-32 cells but not SK-N-SH cells. GD2-targeted NIR-PIT significantly suppressed the viability of GD2-positive NB cells but not GD2-negative NB cells, compared to the control and monotherapy groups. GD2-targeted NIR-PIT significantly reduced the volume of GD2-positive CHP-134 tumor spheres by inducing the accumulation of dead cells. Subcutaneous CHP-134 xenograft tumor models demonstrated that GD2-targeted NIR-PIT significantly inhibited tumor growth compared with the control and monotherapy groups.

GD2-targeted NIR-PIT is a promising antitumor strategy for treating high-risk NB tumors expressing GD2.