Everolimus in combination with crizotinib synergistically inhibits the growth of ALK-positive anaplastic large cell lymphoma cells

Abstract

Anaplastic large cell lymphoma (ALCL) is a rare, aggresive type of non-Hodgkin lymphoma, more than half of which harbors an aberrant NPM-ALK fusion protein. Both mTOR inhibitor everolimus and ALK inhibitor crizotinib have shown promising antitumor activity in ALK-positive cancer cell lines. However, their combined effect has not yet been investigated. This study aimed to evaluate the combined effect of everolimus and crizotinib in ALK-positive ALCL cell lines, Karpas 299 and SU-DHL-1. Western blot and flow cytometry were performed to elucidate the mechanism of combined effect as well. The results show that the combination of everolimus and crizotinib synergistically inhibit the growth of ALK-positive ALCL cells. Crizotinib attenuated ERK and AKT phosphorylation caused by everolimus. The combination treatment induced G1 cell-cycle arrest and increased apoptosis in ALK-positive ALCL cells. The synergistic effect of everolimus and crizotinib was also found in the non-small cell lung cancer cell line, NCI-H2228, that harbors a EML4-ALK fusion gene. In summary, everolimus combined with crizotinib synergistically inhibited the growth of ALK-positive ALCL cells by inhibiting ALK and mTOR phosphorylation and thus indirectly preventing aberrant ERK and AKT phosphorylation. Our results suggest that this combination could be used to improve the therapeutic outcome in patients with ALK-positive ALCL.