Cabozantinib overcomes crizotinib resistance in ROS1 fusion-positive cancer.

ROS1 rearrangement leads to constitutive ROS1 activation with potent transforming activity. In an ongoing phase I trial, the ALK tyrosine kinase inhibitor (TKI) crizotinib shows remarkable initial responses in patients with non-small cell lung cancer (NSCLC) harboring ROS1 fusions; however, cancers eventually develop crizotinib resistance due to acquired mutations such as G2032R in ROS1. Thus, understanding the crizotinib-resistance mechanisms in ROS1-rearranged NSCLC and identification of therapeutic strategies to overcome the resistance are required. The sensitivity of CD74-ROS1-transformed Ba/F3 cells to multiple ALK inhibitors was examined. Acquired ROS1 inhibitor-resistant mutations in CD74-ROS1 fusion were screened by N-ethyl-N-nitrosourea mutagenesis with Ba/F3 cells. To overcome the resistance mutation, we performed high-throughput drug screening with small-molecular inhibitors and anticancer drugs used in clinical practice or being currently tested in clinical trials. The effect of the identified drug was assessed in the CD74-ROS1-mutant Ba/F3 cells and crizotinib-resistant patient-derived cancer cells (MGH047) harboring G2032R-mutated CD74-ROS1. We identified multiple novel crizotinib-resistance mutations in the ROS1 kinase domain, including the G2032R mutation. As the result of high-throughput drug screening, we found that the cMET/RET/VEGFR inhibitor cabozantinib (XL184) effectively inhibited the survival of CD74-ROS1 wild-type (WT) and resistant mutants harboring Ba/F3 and MGH047 cells. Furthermore, cabozantinib could overcome all the resistance by all newly identified secondary mutations. We developed a comprehensive model of acquired resistance to ROS1 inhibitors in NSCLC with ROS1 rearrangement and identified cabozantinib as a therapeutic strategy to overcome the resistance.

Katayama R ，Kobayashi Y ，Friboulet L ，Lockerman EL ，Koike S ，Shaw AT ，Engelman JA ，Fujita N ... -  《-》

CD74-ROS1 G2032R mutation transcriptionally up-regulates Twist1 in non-small cell lung cancer cells leading to increased migration, invasion, and resistance to crizotinib.

The c-ros oncogene 1 (ROS1) is a receptor tyrosine kinase, which has been identified as an oncogene driver of non-small-cell lung cancer (NSCLC). Although crizotinib has a prominent effect on ROS1, resistance is inevitable. Development of the acquired ROS1 G2032R mutation has been reported as a resistant mechanism to ROS1 inhibitors in ROS1-rearranged (ROS1+) NSCLC patients. To explore the mechanism of drug resistance, we constructed the crizotinib resistance cell line, A549-CD74-ROS1 G2032R mutation cells, by the methods of fusion polymerase chain reaction (PCR), plasmid construction and cell transfection in vitro. The results showed that the expression of CD74-ROS1 or CD74-ROS1 G2032R mutation in A549 cells induced epithelial-mesenchymal transition (EMT), dramatically enhanced the ability of invasion and migration, and increased expression of matrix metalloproteinase (MMP)-9 and Twist1 transcription factor. Moreover, we found that inhibition of Twist1 could reverse EMT induced by CD74-ROS1 G2032R mutation. Combination of Twist1 siRNA and crizotinib significantly reduced cell vitality, inhibited cell invasion and migration, and promoted apoptosis in A549-CD74-ROS1 G2032R mutation cells. Taken together, these results suggested that CD74-ROS1 G2032R mutation mediated EMT phenotype by increasing the expression of Twist1, resulting in drug resistance. Combination of Twist1 silence and ROS1 inhibitor may provide a potent strategy to treat the ROS1+ NSCLC patients with crizotinib resistance.

Gou W ，Zhou X ，Liu Z ，Wang L ，Shen J ，Xu X ，Li Z ，Zhai X ，Zuo D ，Wu Y ... -  《-》

Combined effect of cabozantinib and gefitinib in crizotinib-resistant lung tumors harboring ROS1 fusions.

The ROS1 tyrosine kinase inhibitor (TKI) crizotinib has shown dramatic effects in patients with non-small cell lung cancer (NSCLC) harboring ROS1 fusion genes. However, patients inevitably develop resistance to this agent. Therefore, a new treatment strategy is required for lung tumors with ROS1 fusion genes. In the present study, lung cancer cell lines, HCC78 harboring SLC34A2-ROS1 and ABC-20 harboring CD74-ROS1, were used as cell line-based resistance models. Crizotinib-resistant HCC78R cells were established from HCC78. We comprehensively screened the resistant cells using a phosphor-receptor tyrosine kinase array and RNA sequence analysis by next-generation sequencing. HCC78R cells showed upregulation of HB-EGF and activation of epidermal growth factor receptor (EGFR) phosphorylation and the EGFR signaling pathway. Recombinant HB-EGF or EGF rendered HCC78 cells or ABC-20 cells resistant to crizotinib. RNA sequence analysis by next-generation sequencing revealed the upregulation of AXL in HCC78R cells. HCC78R cells showed marked sensitivity to EGFR-TKI or anti-EGFR antibody treatment in vitro. Combinations of an AXL inhibitor, cabozantinib or gilteritinib, and an EGFR-TKI were more effective against HCC78R cells than monotherapy with an EGFR-TKI or AXL inhibitor. The combination of cabozantinib and gefitinib effectively inhibited the growth of HCC78R tumors in an in vivo xenograft model of NOG mice. The results of this study indicated that HB-EGF/EGFR and AXL play roles in crizotinib resistance in lung cancers harboring ROS1 fusions. The combination of cabozantinib and EGFR-TKI may represent a useful alternative treatment strategy for patients with advanced NSCLC harboring ROS1 fusion genes.

Kato Y ，Ninomiya K ，Ohashi K ，Tomida S ，Makimoto G ，Watanabe H ，Kudo K ，Matsumoto S ，Umemura S ，Goto K ，Ichihara E ，Ninomiya T ，Kubo T ，Sato A ，Hotta K ，Tabata M ，Toyooka S ，Maeda Y ，Kiura K ... -  《-》

Molecular Changes Associated with Acquired Resistance to Crizotinib in ROS1-Rearranged Non-Small Cell Lung Cancer.

Although ROS1-rearranged non-small cell lung cancer (NSCLC) is sensitive to crizotinib, development of resistance is inevitable. Here, we identified molecular alterations in crizotinib-resistant tumors from two NSCLC patients with the CD74-ROS1 rearrangement, and in HCC78 cells harboring SLC34A2-ROS1 that showed resistance to crizotinib (HCC78CR cells). ROS1 kinase domain mutations were examined in fresh tumor tissues from two NSCLC patients and HCC78CR1-3 cells by direct sequencing. Ba/F3 cells expressing ROS1 secondary mutations were constructed to evaluate resistance to crizotinib. An upregulated pathway was identified using phospho-receptor tyrosine kinase array, EGFR signaling antibody array, and RNA sequencing (RNA-seq). Cell proliferation and ROS1 downstream signaling pathways were compared between HCC78 and HCC78CR1-3 cells. The ROS1 G2032R mutation was identified in crizotinib-resistant tumors from one patient. Furthermore, HCC78CR1 and CR2 cells harbored a novel ROS1 L2155S mutation (73.3% and 76.2%, respectively). ROS1 G2032R and L2155S mutations conferred resistance to crizotinib in Ba/F3 cells. Evidence of epithelial-to-mesenchymal transition with downregulated E-cadherin and upregulated vimentin was observed in HCC78CR1-2 cells and in the other patient. RNA-seq and EGFR signaling antibody array revealed that the EGFR pathway was significantly upregulated in HCC78CR3 versus HCC78 cells. Cells with the ROS1 mutation and upregulated EGFR were sensitive to foretinib, an inhibitor of c-MET, VEGFR2, and ROS1 and irreversible EGFR tyrosine kinase inhibitors plus crizotinib, respectively. Molecular changes associated with acquired crizotinib resistance in ROS1-rearranged NSCLC are heterogeneous, including ROS1 tyrosine kinase mutations, EGFR activation, and epithelial-to-mesenchymal transition.

Song A ，Kim TM ，Kim DW ，Kim S ，Keam B ，Lee SH ，Heo DS ... -  《-》

TKI-addicted ROS1-rearranged cells are destined to survival or death by the intensity of ROS1 kinase activity.

Ogura H ，Nagatake-Kobayashi Y ，Adachi J ，Tomonaga T ，Fujita N ，Katayama R ... -  《Scientific Reports》