Project description:Crizotinib, an inhibitor of anaplastic lymphoma kinase (ALK), has also recently shown efficacy in the treatment of lung cancers with ROS1 translocations. Resistance to crizotinib developed in a patient with metastatic lung adenocarcinoma harboring a CD74-ROS1 rearrangement who had initially shown a dramatic response to treatment. We performed a biopsy of a resistant tumor and identified an acquired mutation leading to a glycine-to-arginine substitution at codon 2032 in the ROS1 kinase domain. Although this mutation does not lie at the gatekeeper residue, it confers resistance to ROS1 kinase inhibition through steric interference with drug binding. The same resistance mutation was observed at all the metastatic sites that were examined at autopsy, suggesting that this mutation was an early event in the clonal evolution of resistance. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT00585195.).
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:BackgroundThe vast majority of patients with ROS1 positive non-small cell lung cancer (NSCLC) derive clinical benefit from currently approved ROS1 therapies, including crizotinib and entrectinib. However, a small proportion of patients treated with ROS1 inhibitors fail to derive any clinical benefit and demonstrate rapid disease progression. The biological mechanisms underpinning intrinsic resistance remain poorly understood for oncogene-driven cancers.MethodsWe generated a patient-derived cell line, CUTO33, from a ROS1 therapy naive patient with CD74-ROS1+ NSCLC, who ultimately did not respond to a ROS1 inhibitor. We evaluated a panel of ROS1+ patient-derived NSCLC cell lines and used cell-based assays to determine the mechanism of intrinsic resistance to ROS1 therapy.ResultsThe CUTO33 cell line expressed the CD74-ROS1 gene fusion at the RNA and protein level. The ROS1 fusion protein was phosphorylated at baseline consistent with the known intrinsic activity of this oncogene. ROS1 phosphorylation could be inhibited using a wide array of ROS1 inhibitors, however these inhibitors did not block cell proliferation, confirming intrinsic resistance in this model and consistent with the patient's lack of response to a ROS1 inhibitor. CUTO33 expressed high levels of AXL, which has been associated with drug resistance. Combination of an AXL inhibitor or AXL knockdown with a ROS1 inhibitor partially reversed resistance.ConclusionsIn summary, we demonstrate that AXL overexpression is a mechanism of intrinsic resistance to ROS1 inhibitors.
Project description:IntroductionPatients 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.MethodsAn 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.ResultsKIT(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.ConclusionsActivation 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.
Project description:Patients with ROS1-rearranged NSCLC demonstrate excellent disease control with ROS1-targeted therapy, but acquired resistance is inevitable. Of particular interest is the ROS1 L2086F kinase domain mutation which is refractory to all currently available ROS1 TKIs apart from cabozantinib. We present a case of a patient with metastatic ROS1-rearranged NSCLC with dual ROS1 F2004V and L2086F resistance mutations who radiographically responded to the combination of lorlatinib and cabozantinib in a patient with metastatic NSCLC. Furthermore, the patient experienced exceptional clinical improvement and tolerance with the combined use of lorlatinib and cabozantinib. This case builds the case for cabozantinib as an agent to overcome ROS1 L2086F resistance. It also highlights the efficacy and safety of using combination of ROS1 TKIs to overcome complex resistance patterns.
Project description:ROS1-rearranged (also known as ROS1 fusion-positive) non-small-cell lung cancer is an uncommon but distinct molecular subgroup seen in approximately 1-2% of cases. Oncogene addiction due to constitutive ROS1 tyrosine kinase activation has allowed development of molecularly targeted therapies with remarkable anti-tumor activity. Both crizotinib and entrectinib, multitargeted tyrosine kinase inhibitors (TKIs) have now received approval by the FDA for treatment of patients with advanced ROS1-rearranged lung cancers; however, the clinical efficacy and safety of these drugs have been derived from expansion cohorts of single-arm phase I or basket clinical trials with relatively small populations of this clinically and molecularly distinct subgroup. Both drugs lead to high objective response rates (approximately 70-80%) and have manageable side effects, although only entrectinib has potent intracranial efficacy. Lorlatinib is an oral brain-penetrant ALK/ROS1 TKI with activity in both TKI-naïve and some crizotinib-resistant settings (albeit with limited potency against the crizotinib/entrectinib-resistant ROS1-G2032R mutation). We describe cases of advanced ROS1-rearranged lung cancer receiving crizotinib, entrectinib, and/or lorlatinib in first and later line treatment settings to dissect the current state of evidence supporting management decisions for these patients. The next generation ROS1 TKIs (repotrectinib and DS-6051b), owing to their broad activity against kinase mutations including ROS1-G2032R in preclinical studies, hold promise to transform the current treatment paradigm and permit even further gains with regards to long-term outcomes in this subset of patients.
Project description:IntroductionROS1-rearranged (ROS1+) non-small-cell lung cancer (NSCLC) is a rare lung cancer with limited treatment options. Phase I-II studies with ROS1-tyrosine kinase inhibitors (TKIs) included small numbers of patients and real-world data are lacking. We investigate the efficacy and safety of lorlatinib, a third-generation TKI targeting ALK and ROS1, in patients with ROS1+ NSCLC treated through an expanded access program.MethodsConsecutive patients with advanced ROS1+ NSCLC treated with lorlatinib between October 2015 and June 2019 were included. Data were collected from medical records. The primary endpoint was progression-free survival.ResultsOut of the 80 patients included, 47(59%) were female, 49(62%) never smokers (less than 100 cigarettes over the lifetime), and 68(85%) had stage IV NSCLC at diagnosis. Most frequent histology was adenocarcinoma (95%) and median age was 58.2 years. At the time of lorlatinib initiation, 51(64%) patients had brain metastases and 55(81%) were PS 0-1. Lorlatinib was administered as second/third/fourth/fifth+ line in 29%/28%/18%/26% of patients. All patients previously received at least one ROS1 TKI, and 55(69%) previously received chemotherapy. Median follow-up from lorlatinib initiation was 22.2 months. Median progression-free survival and overall survival from lorlatinib initiation were 7.1 months [95% confidence interval (CI) 5.0-9.9 months] and 19.6 months (95% CI 12.3-27.5 months). Median duration of treatment with lorlatinib was 7.4 months (95% CI 6.5-13.1 months). Overall response and disease control rates were 45% and 82%, respectively. The central nervous system response rate was 72%. Treatment was stopped due to toxicity in 10 patients (13%). The safety profile was consistent with previously published data.ConclusionsLorlatinib is a major treatment option for advanced refractory ROS1+ NSCLC in treatment strategy.
Project description:The coexistence of lung cancer and pulmonary tuberculosis (PTB) is uncommon in young patients. We report a case of 22-year-old man who presented with a one-month history of chest pain, cough, slight haemoptysis and weight loss. Following two acid fast bacilli positive sputum samples, a diagnosis of TB was concluded. However, his response to anti-TB therapy was inadequate. A CT scan and further laboratory tests assisted the final diagnosis as c-ros oncogene 1 (ROS1) rearranged lung adenocarcinoma and PTB. Despite severe comorbidities, the patient achieved clinical remission following treatment with the anti-cancer drug, crizotinib and anti- TB therapy. Clinicians should be aware that this comorbidity can occur in all age groups and the clinical and radiological symptoms of the two diseases are similar.
Project description:Histologic transformation from non-small cell to small cell lung cancer has been reported as a resistance mechanism to targeted therapy in EGFR-mutant and ALK fusion-positive lung cancers. Whether small cell transformation occurs in other oncogene-driven lung cancers remains unknown. Here we analyzed the genomic landscape of two pre-mortem and 11 post-mortem metastatic tumors collected from an advanced, ROS1 fusion-positive lung cancer patient, who had received sequential ROS1 inhibitors. Evidence of small cell transformation was observed in all metastatic sites at autopsy, with inactivation of RB1 and TP53, and loss of ROS1 fusion expression. Whole-exome sequencing revealed minimal mutational and copy number heterogeneity, suggestive of "hard" clonal sweep. Patient-derived models generated from autopsy retained features consistent with small cell lung cancer and demonstrated resistance to ROS1 inhibitors. This case supports small cell transformation as a recurring resistance mechanism, and underscores the importance of elucidating its biology to expand therapeutic opportunities.