Spectrum of Mechanisms of Resistance to Crizotinib and Lorlatinib in ROS1 Fusion-Positive Lung Cancer.

Current standard initial therapy for advanced, ROS proto-oncogene 1, receptor tyrosine kinase fusion (ROS1)-positive (ROS1+) non-small cell lung cancer (NSCLC) is crizotinib or entrectinib. Lorlatinib, a next-generation anaplastic lymphoma kinase/ROS1 inhibitor, recently demonstrated efficacy in ROS1+ NSCLC, including in crizotinib-pretreated patients. However, mechanisms of lorlatinib resistance in ROS1+ disease remain poorly understood. Here, we assessed mechanisms of resistance to crizotinib and lorlatinib. Biopsies from patients with ROS1 + NSCLC progressing on crizotinib or lorlatinib were profiled by genetic sequencing. From 55 patients, 47 post-crizotinib and 32 post-lorlatinib biopsies were assessed. Among 42 post-crizotinib and 28 post-lorlatinib biopsies analyzed at distinct timepoints, ROS1 mutations were identified in 38% and 46%, respectively. ROS1 G2032R was the most commonly occurring mutation in approximately one third of cases. Additional ROS1 mutations included D2033N (2.4%) and S1986F (2.4%) post-crizotinib and L2086F (3.6%), G2032R/L2086F (3.6%), G2032R/S1986F/L2086F (3.6%), and S1986F/L2000V (3.6%) post-lorlatinib. Structural modeling predicted ROS1L2086F causes steric interference to lorlatinib, crizotinib, and entrectinib, while it may accommodate cabozantinib. In Ba/F3 models, ROS1L2086F, ROS1G2032R/L2086F, and ROS1S1986F/G2032R/L2086F were refractory to lorlatinib but sensitive to cabozantinib. A patient with disease progression on crizotinib and lorlatinib and ROS1 L2086F received cabozantinib for nearly 11 months with disease control. Among lorlatinib-resistant biopsies, we also identified MET amplification (4%), KRAS G12C (4%), KRAS amplification (4%), NRAS mutation (4%), and MAP2K1 mutation (4%). ROS1 mutations mediate resistance to crizotinib and lorlatinib in more than one third of cases, underscoring the importance of developing next-generation ROS1 inhibitors with potency against these mutations, including G2032R and L2086F. Continued efforts are needed to elucidate ROS1-independent resistance mechanisms.

Lin JJ ，Choudhury NJ ，Yoda S ，Zhu VW ，Johnson TW ，Sakhtemani R ，Dagogo-Jack I ，Digumarthy SR ，Lee C ，Do A ，Peterson J ，Prutisto-Chang K ，Malik W ，Hubbeling HG ，Langenbucher A ，Schoenfeld AJ ，Falcon CJ ，Temel JS ，Sequist LV ，Yeap BY ，Lennerz JK ，Shaw AT ，Lawrence MS ，Ou SI ，Hata AN ，Drilon A ，Gainor JF ... -  《-》

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 ... -  《-》

Mechanisms of Resistance to Tyrosine Kinase Inhibitors in ROS1 Fusion-Positive Nonsmall Cell Lung Cancer.

ROS1 fusion-positive (ROS1+) nonsmall cell lung cancer (NSCLC) patients are highly sensitive to tyrosine kinase inhibitor (TKI) treatments. However, acquired TKI resistance remains the major hurdle preventing patients from experiencing prolonged benefits. 107 advanced or metastatic ROS1+ NSCLC patients who progressed on crizotinib and lorlatinib were recruited. Tissue and plasma samples were collected at baseline (N = 50), postcrizotinib (N = 91), and postlorlatinib (N = 21), which were all subject to the 139-gene targeted next-generation DNA sequencing. Molecular dynamics modeling was performed to investigate the effects of ROS1 mutations on binding to different TKIs. In patients with postcrizotinib and postlorlatinib samples, an accumulation of on- and off-target resistance alterations after multiple TKI treatments was observed. ROS1 G2032R and MET amplification were the most common on-target and off-target alterations, respectively. Patients with CD74-ROS1 and SLC34A2-ROS1 had longer progression-free survival (PFS) (P < 0.001) and higher rates of resistance mutations (on-target, P = 0.001; off-target, P = 0.077) than other ROS1 fusion variants following crizotinib treatment. Ten distinct on-target resistance mutations were detected after TKI therapies, of which 4 were previously unreported (ROS1 L2010M, G1957A, D1988N, L1982V). Molecular dynamics simulations showed that all 4 mutations were refractory to crizotinib, while G1957A, D1988N, and L1982V were potentially sensitive to lorlatinib and entrectinib. This study provided a comprehensive portrait of TKI-resistance mechanisms in ROS1+ NSCLC patients. Using in silico simulations of TKI activity, novel secondary mutations that may confer TKI resistance were identified and may support clinical therapeutic decision-making.

Zhao X ，Zhang X ，Chen H ，Bao H ，Wu X ，Wang H ，Bao H ，Pang J ，Wang S ，Wang J ... -  《-》

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 ... -  《-》

Crizotinib-Resistant ROS1 Mutations Reveal a Predictive Kinase Inhibitor Sensitivity Model for ROS1- and ALK-Rearranged Lung Cancers.

The identification of molecular mechanisms conferring resistance to tyrosine kinase inhibitor (TKI) is a key step to improve therapeutic results for patients with oncogene addiction. Several alterations leading to EGFR and anaplastic lymphoma kinase (ALK) resistance to TKI therapy have been described in non-small cell lung cancer (NSCLC). Only two mutations in the ROS1 kinase domain responsible for crizotinib resistance have been described in patients thus far. A patient suffering from a metastatic NSCLC harboring an ezrin (EZR)-ROS1 fusion gene developed acquired resistance to the ALK/ROS1 inhibitor crizotinib. Molecular analysis (whole-exome sequencing, CGH) and functional studies were undertaken to elucidate the mechanism of resistance. Based on this case, we took advantage of the structural homology of ROS1 and ALK to build a predictive model for drug sensitivity regarding future ROS1 mutations. Sequencing revealed a dual mutation, S1986Y and S1986F, in the ROS1 kinase domain. Functional in vitro studies demonstrated that ROS1 harboring either the S1986Y or the S1986F mutation, while conferring resistance to crizotinib and ceritinib, was inhibited by lorlatinib (PF-06463922). The patient's clinical response confirmed the potency of lorlatinib against S1986Y/F mutations. The ROS1 S1986Y/F and ALK C1156Y mutations are homologous and displayed similar sensitivity patterns to ALK/ROS1 TKIs. We extended this analogy to build a model predicting TKI efficacy against potential ROS1 mutations. Clinical evidence, in vitro validation, and homology-based prediction provide guidance for treatment decision making for patients with ROS1-rearranged NSCLC who progressed on crizotinib. Clin Cancer Res; 22(24); 5983-91. ©2016 AACR.

Facchinetti F ，Loriot Y ，Kuo MS ，Mahjoubi L ，Lacroix L ，Planchard D ，Besse B ，Farace F ，Auger N ，Remon J ，Scoazec JY ，André F ，Soria JC ，Friboulet L ... -  《-》