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Patterns of Metastatic Spread and Mechanisms of Resistance to Crizotinib in ROS1-Positive Non-Small-Cell Lung Cancer.

ABSTRACT: PURPOSE:The ROS1 tyrosine kinase is activated through ROS1 gene rearrangements in 1-2% of non-small cell lung cancer (NSCLC), conferring sensitivity to treatment with the ALK/ROS1/MET inhibitor crizotinib. Currently, insights into patterns of metastatic spread and mechanisms of crizotinib resistance among ROS1-positive patients are limited. PATIENTS AND METHODS:We reviewed clinical and radiographic imaging data of patients with ROS1- and ALK-positive NSCLC in order to compare patterns of metastatic spread at initial metastatic diagnosis. To determine molecular mechanisms of crizotinib resistance, we also analyzed repeat biopsies from a cohort of ROS1-positive patients progressing on crizotinib. RESULTS:We identified 39 and 196 patients with advanced ROS1- and ALK-positive NSCLC, respectively. ROS1-positive patients had significantly lower rates of extrathoracic metastases (ROS1 59.0%, ALK 83.2%, P=0.002), including lower rates of brain metastases (ROS1 19.4%, ALK 39.1%; P = 0.033), at initial metastatic diagnosis. Despite similar overall survival between ALK- and ROS1-positive patients treated with crizotinib (median 3.0 versus 2.5 years, respectively; P=0.786), ROS1-positive patients also had a significantly lower cumulative incidence of brain metastases (34% vs. 73% at 5 years; P<0.0001). Additionally, we identified 16 patients who underwent a total of 17 repeat biopsies following progression on crizotinib. ROS1 resistance mutations were identified in 53% of specimens, including 9/14 (64%) non-brain metastasis specimens. ROS1 mutations included: G2032R (41%), D2033N (6%), and S1986F (6%). CONCLUSIONS:Compared to ALK rearrangements, ROS1 rearrangements are associated with lower rates of extrathoracic metastases, including fewer brain metastases, at initial metastatic diagnosis. ROS1 resistance mutations, particularly G2032R, appear to be the predominant mechanism of resistance to crizotinib, underscoring the need to develop novel ROS1 inhibitors with activity against these resistant mutants.

SUBMITTER: Gainor JF

PROVIDER: S-EPMC5766287 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PurposeCurrent 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.Experimental designBiopsies from patients with ROS1 + NSCLC progressing on crizotinib or lorlatinib were profiled by genetic sequencing.ResultsFrom 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%).ConclusionsROS1 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.

Project description:Patients with non-small cell lung cancer (NSCLC) harboring ROS proto-oncogene 1, receptor tyrosine kinase gene (ROS1) chromosomal rearrangements benefit from treatment with the ROS1 inhibitor crizotinib. Limited data exist on the spectrum of resistance mechanisms in ROS1-positive NSCLC. To delineate mechanisms of acquired resistance, we analyzed biopsy samples of tumor lesions that progressed while patients were receiving crizotinib.An activating mutation in the KIT proto-oncogene receptor tyrosine kinase (KIT) (p.D816G) was identified by SNaPshot sequencing in a tumor sample from a patient with ROS1-positive NSCLC identified by fluorescence in situ hybridization whose disease progressed after initial response to crizotinib. In vitro studies included evaluation of KIT mRNA expression by quantitative reverse-transcriptase polymerase chain reactions, transduction of Ba/F3 cells and NSCLC cell lines with KIT-expressing lentiviral plasmids, immunoblotting, and cellular proliferation assays.KIT(D816G) is an activating mutation that induces autophosphorylation and cell proliferation. Expression of the mutant KIT(D816G) receptor in ROS1-positive NSCLC cell lines led to constitutively activated KIT as measured by phosphorylation of the KIT receptor. Expression of the KIT(D816G) rendered the HCC78 and CUTO2 cell lines resistant to crizotinib, and only dual inhibition of ROS1 and KIT with crizotinib and ponatinib could resensitize the cells to inhibition of proliferation. The oncogenic switch observed in ROS1-positive cell lines was not immediate and required pharmacologic inactivation of ROS1.Activation of KIT by a gain-of-function somatic mutation is a novel mechanism of resistance to crizotinib in ROS1-rearranged NSCLC. This bypass signaling pathway serves as a ROS1-independent mechanism of resistance, similarly to previously identified epidermal growth factor receptor or Kirsten rat sarcoma viral oncogene homolog/neuroblastoma RAS viral oncogene homolog signaling pathways, and can potentially be targeted by KIT inhibitors.

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Patterns of Metastatic Spread and Mechanisms of Resistance to Crizotinib in ROS1-Positive Non-Small-Cell Lung Cancer.

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