Synergistic Antitumor Effects of 177Lu-Octreotide Combined with an ALK Inhibitor in a High-Risk Neuroblastoma Xenograft Model

Abstract

Background/Objectives: Neuroblastoma (NB) is a childhood cancer with heterogeneous characteristics, posing challenges to effective treatment. NBs express somatostatin receptors that facilitate the use of somatostatin analogs (SSTAs) as tumor-seeking agents for diagnosis and therapy. High-risk (HR) NBs often have gain-of-function mutations in the receptor tyrosine kinase anaplastic lymphoma kinase (ALK). Despite intensive multimodal treatment, survival rates remain below 40% for children with HR-NB. The aim of this work was to investigate the combined effect of the SSTA 177Lu-octreotide with the ALK inhibitor lorlatinib. Methods: Mice bearing human HR-NB CLB-BAR tumors were treated with lorlatinib, 177Lu-octreotide, and a combination of these pharmaceuticals or saline (control). Tumor volume was monitored and tumor samples were evaluated for cleaved caspase-3 and expression of 84 human genes involved in apoptosis. Results: Combination treatment with 177Lu-octreotide and lorlatinib demonstrated synergistic antitumor effects. An increased number of cleaved caspase 3-positive cells was observed in tumors from mice treated with 177Lu-octreotide alone and in combination with lorlatinib. Modulation of Bcl-2 family gene expression was observed only in the presence of both 177Lu-octreotide and lorlatinib, with BID down-regulated and HRK up-regulated on days 2 and 7, respectively. Conclusions: The data suggest that ALK signaling pathway inhibition may contribute to radiosensitization in radionuclide therapy with 177Lu-octreotide and could improve treatment outcomes in patients with HR-NB.