Oral Metronomic Topotecan Sensitizes Crizotinib Antitumor Activity in ALKF1174L Drug-Resistant Neuroblastoma Preclinical Models

Libo Zhang; Bing Wu; Sylvain Baruchel

doi:10.1016/j.tranon.2017.04.008

Oral Metronomic Topotecan Sensitizes Crizotinib Antitumor Activity in ALK^F1174L Drug-Resistant Neuroblastoma Preclinical Models

Transl Oncol. 2017 Aug;10(4):604-611. doi: 10.1016/j.tranon.2017.04.008. Epub 2017 Jun 27.

Authors

Libo Zhang¹, Bing Wu¹, Sylvain Baruchel²

Affiliations

¹ New Agent and Innovative Therapy Program, The Hospital for Sick Children, Toronto, Canada; Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Canada.
² New Agent and Innovative Therapy Program, The Hospital for Sick Children, Toronto, Canada; Division of Hematology and Oncology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Canada; Institute of Medical Sciences, University of Toronto, Toronto, Canada. Electronic address: sylvain.baruchel@sickkids.ca.

Abstract

Background: Anaplastic lymphoma kinase (ALK) inhibitor crizotinib has proven to be effective in the treatment of ALK-mutated neuroblastoma, but crizotinib resistance was commonly observed in patients. We aimed to overcome crizotinib resistance by combining with the MEK inhibitor trametinib or low-dose metronomic (LDM) topotecan in preclinical neuroblastoma models.

Methods: We selected a panel of neuroblastoma cell lines carrying various ALK genetic aberrations to assess the therapeutic efficacy on cell proliferation in vitro. Downstream signals of ALK activation, including phosphorylation of ERK1/2, Akt as well as HIF-1α expression were evaluated under normoxic and hypoxic conditions. Tumor growth inhibition was further assessed in NOD/SCID xenograft mouse models.

Results: All NBL cell lines responded to crizotinib treatment but at variable ED50 levels, ranging from 0.25 to 5.58 μM. ALK-mutated cell lines SH-SY5Y, KELLY, LAN-5, and CHLA-20 are more sensitive than ALK wild-type cell lines. In addition, we demonstrated that under hypoxic conditions, all NBL cell lines showed marked decrease of ED50s when compared to normoxia except for KELLY cells. Taking into consideration the hypoxia sensitivity to crizotinib, combined treatment with crizotinib and LDM topotecan demonstrated a synergistic effect in ALK^F1174L-mutated SH-SY5Y cells. In vivo, single-agent crizotinib showed limited antitumor activity in ALK^F1174L-mutated SH-SY5Y and KELLY xenograft models; however, when combined with topotecan, significantly delayed tumor development was achieved in both SH-SY5Y and KELLY tumor models.

Conclusions: Oral metronomic topotecan reversed crizotinib drug resistance in the ALK^F1174L-mutated neuroblastoma preclinical model.