Assessment of a New ROS1 Immunohistochemistry Clone (SP384) for the Identification of ROS1 Rearrangements in Patients with Non–Small Cell Lung Carcinoma: the ROSING Study

IntroductionThe ROS1 gene rearrangement has become an important biomarker in NSCLC. The College of American Pathologists/International Association for the Study of Lung Cancer/Association for Molecular Pathology testing guidelines support the use of ROS1 immunohistochemistry (IHC) as a screening test, followed by confirmation with fluorescence in situ hybridization (FISH) or a molecular test in all positive results. We have evaluated a novel anti-ROS1 IHC antibody (SP384) in a large multicenter series to obtain real-world data.MethodsA total of 43 ROS1 FISH–positive and 193 ROS1 FISH–negative NSCLC samples were studied. All specimens were screened by using two antibodies (clone D4D6 from Cell Signaling Technology and clone SP384 from Ventana Medical Systems), and the different interpretation criteria were compared with break-apart FISH (Vysis). FISH-positive samples were also analyzed with next-generation sequencing (Oncomine Dx Target Test Panel, Thermo Fisher Scientific).ResultsAn H-score of 150 or higher or the presence of at least 70% of tumor cells with an intensity of staining of 2+ or higher by the SP384 clone was the optimal cutoff value (both with 93% sensitivity and 100% specificity). The D4D6 clone showed similar results, with an H-score of at least 100 (91% sensitivity and 100% specificity). ROS1 expression in normal lung was more frequent with use of the SP384 clone (p < 0.0001). The ezrin gene (EZR)-ROS1 variant was associated with membranous staining and an isolated green signal FISH pattern (p = 0.001 and p = 0.017, respectively).ConclusionsThe new SP384 ROS1 IHC clone showed excellent sensitivity without compromising specificity, so it is another excellent analytical option for the proposed testing algorithm.     

On the relevance of a testing algorithm for the detection of ROS1-rearranged lung adenocarcinomas

Objectives

ROS1 proto-oncogene translocations define a new molecular subgroup in non-small cell lung cancers (NSCLC) and are associated with a response to the MET/ALK inhibitor, crizotinib. These rearrangements are described in 0.9–1.7% NSCLC, in wild-type EGFR, KRAS and ALK (“triple negative”) lung adenocarcinomas. Rapid and efficient identification of these alterations is thus becoming increasingly important.

Materials and methods

In this study, 121 triple negative lung adenocarcinomas were screened by both IHC with the ROS1 D4D6 antibody, and FISH using two commercially available ROS1 break-apart probes. To address a possible cross-reactivity of the ROS1 antibody with other protein kinase receptors, we screened 80 additional cases with known EGFR, KRAS, PI3KCA, BRAF, HER2 mutations or ALK-rearrangement.

Results

We diagnosed 9 ROS1-rearranged adenocarcinomas, with both a positive FISH result (51–87% rearranged nuclei) and a positive IHC staining (2+/3+ cytoplasmic staining). Only one of the ROS1-positive FISH cases was characterized by a classical split pattern, the others showed a variant pattern, most commonly involving a loss of the 5′ telomeric probe. Considering a positivity threshold of 2+ stained cells, the sensitivity of the ROS1 D4D6 antibody compared to FISH was 100% and the specificity 96.9%, as two HER2-mutated tumors were positive with D4D6 antibody, without any translocation in FISH. All the ROS1-positive cases were at an advanced stage, arising in never or light smokers. They were mainly solid cribriform and acinar adenocarcinomas, with signet ring cells noted in 5 cases, and calcifications in 3 cases. One positive case was an invasive mucinous carcinoma.

Conclusion

Our results show that a screening algorithm based on an IHC detection of ROS1 fusion proteins, confirmed if positive or doubtful by a ROS1 break-apart FISH assay, is pertinent in advanced “triple negative” lung adenocarcinomas, since the prevalence of ROS1-positive cases in this selected population reaches 7.4% in our series.     

High Prevalence of Concomitant Oncogene Mutations in Prospectively Identified Patients with ROS1-Positive Metastatic Lung Cancer

ObjectivesChromosomal rearrangements involving ROS1 define a rare entity of lung adenocarcinomas with exquisite sensitivity to molecularly targeted therapy. We report clinical outcomes and genomic findings of patients with ROS1-positive lung cancer who were prospectively identified within a multiplex biomarker profiling program at the West German Cancer Center.MethodsStandardized immunohistochemical (IHC) analysis, fluorescence in situ hybridization (FISH), and hotspot mutation analyses were performed in 1345 patients with advanced cancer, including 805 patients with metastatic lung adenocarcinoma. Clinical and epidemiological data were retrieved from the institutional database.ResultsROS1 positivity by IHC analysis was detected in 25 patients with lung cancer (4.8% of lung adenocarcinomas), including 13 patients (2.5%) with ROS1 FISH positivity with a cutoff of at least 15% of events. Of the ROS1 IHC analysis–positive cases, 36% presented with concomitant oncogenic driver mutations involving EGFR (six cases, five of which were clinically validated by response to EGFR-targeting agents), KRAS (two cases), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha gene (PIK3CA), and BRAF. Three cases initially classified as ROS1 FISH–negative passed the threshold of 15% positive events when repeat biopsies were analyzed at progression. The median overall survival of the ROS1-positive patients (104 months) was significantly superior to that of the 261 patients with EGFR/anaplastic lymphoma kinase/ROS1–negative lung adenocarcinoma (24.4 months, p = 0.044). Interestingly, the overall survival of the 13 ROS1-positive patients with lung cancer from initiation of pemetrexed-based chemotherapy was significantly prolonged when compared with that of 169 pemetrexed-treated patients with EGFR/anaplastic lymphoma kinase/ROS1–negative adenocarcinoma (p = 0.01).ConclusionsROS1-positive metastatic lung adenocarcinomas frequently harbor concomitant oncogenic driver mutations. Levels of ROS1 FISH–positive events are variable over time. This heterogeneity provides additional therapeutic options if discovered by multiplex biomarker testing and repeat biopsies.     

Reflex ROS1 IHC Screening with FISH Confirmation for Advanced Non-Small Cell Lung Cancer—A Cost-Efficient Strategy in a Public Healthcare System

ROS1 rearrangements are identified in 1–2% of lung adenocarcinoma cases, and reflex testing is guideline-recommended. We developed a decision model for population-based ROS1 testing from a Canadian public healthcare perspective to determine the strategy that optimized detection of true-positive (TP) cases while minimizing costs and turnaround time (TAT). Eight diagnostic strategies were compared, including reflex single gene testing via immunohistochemistry (IHC) screening, fluorescence in-situ hybridization (FISH), next-generation sequencing (NGS), and biomarker-informed (EGFR/ALK/KRAS wildtype) testing initiated by pathologists and clinician-initiated strategies. Reflex IHC screening with FISH confirmation of positive cases yielded the best results for TAT, TP detection rate, and cost. IHC screening saved CAD 1,000,000 versus reflex FISH testing. NGS was the costliest reflex strategy. Biomarker-informed testing was cost-efficient but delayed TAT. Clinician-initiated testing was the least costly but resulted in long TAT and missed TP cases, highlighting the importance of reflex testing. Thus, reflex IHC screening for ROS1 with FISH confirmation provides a cost-efficient strategy with short TAT and maximizes the number of TP cases detected.     

Discrepancies between FISH and immunohistochemistry for assessment of the ALK status are associated with ALK ‘borderline’-positive rearrangements or a high copy number: a potential major issue for anti-ALK therapeutic strategies

BackgroundPatients with advanced lung adenocarcinomas expressing ALK rearrangements are highly responsive to crizotinib, a dual ALK/c-MET inhibitor. Immunohistochemistry (IHC) is an easy clinically and routinely applicable cost-effective assay for ALK, c-MET and ROS1 protein expression for potential treatment with crizotinib. The purpose of this study was to evaluate the percentage and the pattern of ALK-rearranged cells, the variation in the native ALK copy number, as well as ALK, c-MET and ROS1 protein expression, and their significance on outcome of crizotinib-treated lung adenocarcinoma patients.Patients and methodsConsecutive lung adenocarcinoma specimens (n = 176) ‘double-negative’ (wild-type EGFR and KRAS) were tested for ALK rearrangements/copy number alterations and for ALK, c-MET and ROS1 protein expression using automated standardized protocols. Preliminary data on the outcome of crizotinib-treated patients were recorded.ResultsFISH analysis identified 26/176 (15%) cases with ALK rearrangements. Seven cases had discordant results between the ALK FISH and IHC. Five cases with discordant FISH-positive/IHC-negative revealed FISH ‘borderline’ positivity (15%–20%). Three cases overexpressed c-MET and responded to crizotinib, and two cases with ALK-‘borderline’ rearranged cells only, not associated with c-MET expression, progressed under crizotinib. Two cases with discordant FISH-negative/IHC-positive revealed ALK gene amplification without associated c-MET or ROS1 protein expression.ConclusionsThe discrepancies observed between the IHC and FISH data revealed unexpected biological events, rather than technical issues, which potentially can have a strong impact on the therapeutic strategy with crizotinib.     

NTRK1 rearrangement in colorectal cancer patients: evidence for actionable target using patient-derived tumor cell line

Background

We have investigated the incidence of NTRK1 rearrangements in metastatic gastrointestinal cancer patients and demonstrated the potential for clinical response of these patients to targeted therapy.

Methods

We prospectively collected tumor tissue specimens for one year and simultaneously generated patient-derived tumor cells (PDCs). Specimens were initially screened for TrkA protein expression using TrkA immunohistochemistry (IHC). In the case of TrkA IHC positive results, samples were further examined by fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) to confirm the presence of NTRK1 rearrangements.

Results

From January 2014 to December 2014, a total of 74 metastatic colorectal cancer (CRC) patients and 66 gastric cancer (GC) patients were initially screened by TrkA IHC. Two of the 74 CRC patients (2.7%) and one of the 66 GC patients (1.5%) were positive for TrkA expression by IHC. All three IHC positive cases had evidence of NTRK1 rearrangements by FISH. NGS was performed on the 3 IHC positive cases and confirmed TPM3-NTRK1 rearrangements in the two CRC cases. One GC patient with TrkA expression by IHC did not harbor an NTRK1 rearrangement. PDCs established from the NTRK1 positive CRC patients were positive for the NTRK1 rearrangement. Entrectinib, a pan-TRK inhibitor, profoundly inhibited cell proliferation of NTRK1-rearranged PDCs with such inhibition associated with inactivation of TrkA, and down-regulation of downstream signaling pathways.

Conclusion

TrkA IHC is an effective, initial screening method for NTRK1 rearrangement detection in the clinic. Inhibition of the TrkA kinase is a promising targeted therapy for cancer patients whose tumors harbor a NTRK1 rearrangement.     

MET IHC Is a Poor Screen for MET Amplification or MET Exon 14 Mutations in Lung Adenocarcinomas: Data from a Tri-Institutional Cohort of the Lung Cancer Mutation Consortium

IntroductionMNNG HOS Transforming gene (MET) amplification and MET exon 14 (METex14) alterations in lung cancers affect sensitivity to MET proto-oncogene, receptor tyrosine kinase (MET [also known by the alias hepatocyte growth factor receptor]) inhibitors. Fluorescence in situ hybridization (FISH), next-generation sequencing (NGS), and immunohistochemistry (IHC) have been used to evaluate MET dependency. Here, we have determined the association of MET IHC with METex14 mutations and MET amplification.MethodsWe collected data on a tri-institutional cohort from the Lung Cancer Mutation Consortium. All patients had metastatic lung adenocarcinomas and no prior targeted therapies. MET IHC positivity was defined by an H-score of 200 or higher using SP44 antibody. MET amplification was defined by copy number fold change of 1.8x or more with use of NGS or a MET-to–centromere of chromosome 7 ratio greater than 2.2 with use of FISH.ResultsWe tested tissue from 181 patients for MET IHC, MET amplification, and METex14 mutations. Overall, 71 of 181 patients (39%) were MET IHC–positive, three of 181 (2%) were MET-amplified, and two of 181 (1%) harbored METex14 mutations. Of the MET-amplified cases, two were FISH positive with MET-to–centromere of chromosome 7 ratios of 3.1 and 3.3, one case was NGS positive with a fold change of 4.4x, and one of the three cases was MET IHC–positive. Of the 71 IHC-positive cases, one (1%) was MET-amplified and two (3%) were METex14-mutated. Of the MET IHC–negative cases, two of 110 (2%) were MET-amplified.ConclusionsIn this study, nearly all MET IHC–positive cases were negative for MET amplification or METex14 mutations. MET IHC can also miss patients with MET amplification. The limited number of MET-amplified cases in this cohort makes it challenging to demonstrate an association between MET IHC and MET amplification. Nevertheless, IHC appears to be an inefficient screen for these genomic changes. MET amplification or METex14 mutations can best be detected by FISH and a multiplex NGS panel.     

High level of chromosomal instability in circulating tumor cells of ROS1-rearranged non-small-cell lung cancer

BackgroundGenetic aberrations affecting the c-ros oncogene 1 (ROS1) tyrosine kinase gene have been reported in a small subset of patients with non-small-cell lung cancer (NSCLC). We evaluated whether ROS1-chromosomal rearrangements could be detected in circulating tumor cells (CTCs) and examined tumor heterogeneity of CTCs and tumor biopsies in ROS1-rearranged NSCLC patients.Patients and methodsUsing isolation by size of epithelial tumor cells (ISET) filtration and filter-adapted-fluorescence in situ hybridization (FA-FISH), ROS1 rearrangement was examined in CTCs from four ROS1-rearranged patients treated with the ROS1-inhibitor, crizotinib, and four ROS1-negative patients. ROS1-gene alterations observed in CTCs at baseline from ROS1-rearranged patients were compared with those present in tumor biopsies and in CTCs during crizotinib treatment. Numerical chromosomal instability (CIN) of CTCs was assessed by DNA content quantification and chromosome enumeration.ResultsROS1 rearrangement was detected in the CTCs of all four patients with ROS1 rearrangement previously confirmed by tumor biopsy. In ROS1-rearranged patients, median number of ROS1-rearranged CTCs at baseline was 34.5 per 3 ml blood (range, 24–55). In ROS1-negative patients, median background hybridization of ROS1-rearranged CTCs was 7.5 per 3 ml blood (range, 7–11). Tumor heterogeneity, assessed by ROS1 copy number, was significantly higher in baseline CTCs compared with paired tumor biopsies in the three patients experiencing PR or SD (P < 0.0001). Copy number in ROS1-rearranged CTCs increased significantly in two patients who progressed during crizotinib treatment (P < 0.02). CTCs from ROS1-rearranged patients had a high DNA content and gain of chromosomes, indicating high levels of aneuploidy and numerical CIN.ConclusionWe provide the first proof-of-concept that CTCs can be used for noninvasive and sensitive detection of ROS1 rearrangement in NSCLC patients. CTCs from ROS1-rearranged patients show considerable heterogeneity of ROS1-gene abnormalities and elevated numerical CIN, a potential mechanism to escape ROS1-inhibitor therapy in ROS1-rearranged NSCLC tumors.     

RET Fluorescence In Situ Hybridization Analysis Is a Sensitive but Highly Unspecific Screening Method for RET Fusions in Lung Cancer

IntroductionRET gene fusions are established oncogenic drivers in 1% of NSCLC. Accurate detection of advanced patients with RET fusions is essential to ensure optimal therapy choice. We investigated the performance of fluorescence in situ hybridization (FISH) as a diagnostic test for detecting functional RET fusions.MethodsBetween January 2016 and November 2019, a total of 4873 patients with NSCLC were routinely screened for RET fusions using either FISH (n = 2858) or targeted RNA next-generation sequencing (NGS) (n = 2015). If sufficient material was available, positive cases were analyzed by both methods (n = 39) and multiple FISH assays (n = 17). In an independent cohort of 520 patients with NSCLC, whole-genome sequencing data were investigated for disruptive structural variations and functional fusions in the RET and compared with ALK and ROS1 loci.ResultsFISH analysis revealed RET rearrangement in 48 of 2858 cases; of 30 rearranged cases double tested with NGS, only nine had a functional RET fusion. RNA NGS yielded RET fusions in 14 of 2015 cases; all nine cases double tested by FISH had RET locus rearrangement. Of these 18 verified RET fusion cases, 16 had a split signal and two a complex rearrangement by FISH. By whole-genome sequencing, the prevalence of functional fusions compared with all disruptive events was lower in the RET (4 of 9, 44%) than the ALK (27 of 34, 79%) and ROS1 (9 of 12, 75%) loci.ConclusionsFISH is a sensitive but unspecific technique for RET screening, always requiring a confirmation using an orthogonal technique, owing to frequently occurring RET rearrangements not resulting in functional fusions in NSCLC.     

Immunohistochemistry for identification of CCND1, NSD2, and MAF gene rearrangements in plasma cell myeloma

The t(11;14)/CCND1‐IGH, t(4;14)/NSD2(MMSET)‐IGH, and t(14;16)/IGH‐MAF gene rearrangements detected by fluorescence in situ hybridization (FISH) are used for risk stratification in patients with multiple myeloma (MM). Compared with conventional FISH techniques using fresh cells, immunohistochemistry (IHC) is much more cost‐ and time‐efficient, and can be readily applied to routinely prepared formalin‐fixed, paraffin‐embedded (FFPE) materials. In this study, we performed tissue FISH and IHC employing FFPE specimens, and examined the usefulness of IHC as a tool for detecting CCND1, NSD2, and MAF gene rearrangements. CD138 signals were used to identify plasma cells in tissue FISH and IHC analyses. With cohort 1 (n = 70), we performed tissue FISH and subsequently IHC, and determined IHC cut‐off points. In this cohort, the sensitivity and specificity for the 3 molecules were ≥.90 and ≥.96, respectively. With cohort 2, using MM cases with an unknown gene status (n = 120), we performed IHC, and the gene status was estimated using the cut‐off points determined with cohort 1. The subsequent FISH analysis showed that the sensitivity and specificity for the 3 molecules were ≥.92 and ≥.98, respectively. CCND1, NSD2, and MAF gene rearrangements were estimated accurately by IHC, suggesting that conventional FISH assays can be replaced by IHC.     

Frequent aerogenous spread with decreased E-cadherin expression of ROS1-rearranged lung cancer predicts poor disease-free survival

ObjectivesROS1 rearrangement has been found in a subset of lung cancer and ROS1-rearranged tumors are sensitive to ALK kinase inhibitors. This study sought to evaluate the clinicopathological implications and histomorphological characteristics of ROS1-rearranged tumors, especially micropapillary and aerogenous spread growth and to investigate the usefulness of ROS1 immunohistochemistry as a diagnostic test for ROS1 rearrangement.Materials and methodsROS1 rearrangement characterizations by fluorescence in situ hybridization and ROS1 protein and E-cadherin expression by immunohistochemistry were performed using 754 non-small cell lung cancer surgical specimens.ResultsROS1 rearrangement was identified in 10 samples. Histologically, all 10 ROS1-rearranged tumors harbored an adenocarcinoma component. Significantly, we noted a high association between ROS1 rearrangement with a micropapillary component (p < 0.001), aerogenous spread (p = 0.002), and E-cadherin loss (p = 0.049). Survival analysis showed that ROS1 rearrangement was significantly associated with a higher risk of tumor recurrence (p = 0.024). The best criterion to detect ROS1-rearrangement by immunohistochemistry was an H-score of ≥100, with a sensitivity and specificity of 90% and 93.5%, respectively.ConclusionsROS1-rearranged adenocarcinoma exhibited distinct morphological and clinicopathological features. Decreased membranous E-cadherin expression and aerogenous spread may be associated with worse disease-free survival. ROS1 immunohistochemistry correlated well with ROS1 gene rearrangement.     

ROS1 Fusions Rarely Overlap with Other Oncogenic Drivers in Non–Small Cell Lung Cancer

IntroductionChromosomal rearrangements involving the gene ROS1 define a distinct molecular subset of NSCLCs with sensitivity to ROS1 inhibitors. Recent reports have suggested a significant overlap between ROS1 fusions and other oncogenic driver alterations, including mutations in EGFR and KRAS.MethodsWe identified patients at our institution with ROS1-rearranged NSCLC who had undergone testing for genetic alterations in additional oncogenes, including EGFR, KRAS, and anaplastic lymphoma receptor tyrosine kinase gene (ALK). Clinicopathologic features and genetic testing results were reviewed. We also examined a separate database of ROS1-rearranged NSCLCs identified through the commercial FoundationOne assay (Foundation Medicine, Cambridge, MA).ResultsAmong 62 patients with ROS1-rearranged NSCLC evaluated at our institution, none harbored concurrent ALK fusions (0%) or EGFR activating mutations (0%). KRAS mutations were detected in two cases (3.2%), one of which harbored a concurrent noncanonical KRAS I24N mutation of unknown biological significance. In a separate ROS1 fluorescence in situ hybridization–positive case, targeted sequencing failed to confirm a ROS1 fusion but instead identified a KRAS G13D mutation. No concurrent mutations in B-Raf proto-oncogene, serine/threonine kinase gene (BRAF), erb-b2 receptor tyrosine kinase 2 gene (ERBB2), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha gene (PIK3CA), AKT/serine threonine kinase 1 gene (AKT1), or mitogen-activated protein kinase kinase 1 gene (MAP2K1) were detected. Analysis of an independent data set of 166 ROS1-rearranged NSCLCs identified by FoundationOne demonstrated rare cases with co-occurring driver mutations in EGFR (one of 166) and KRAS (three of 166) and no cases with co-occurring ROS1 and ALK rearrangements.ConclusionsROS1 rearrangements rarely overlap with alterations in EGFR, KRAS, ALK, or other targetable oncogenes in NSCLC.     

Combinational Analysis of FISH and Immunohistochemistry Reveals Rare Genomic Events in ALK Fusion Patterns in NSCLC that Responds to Crizotinib Treatment

IntroductionThe purpose of this study was to explore the complicated rearrangement mechanisms underlying cases with atypical and negative anaplastic lymphoma receptor tyrosine kinase gene (ALK) fluorescence hybridization (FISH) and positive immunohistochemistry (IHC) results and to stress the importance of combinational assay of these two methods in current pathological diagnosis.MethodsA total of 3128 NSCLCs were screened for ALK fusions through both FISH analysis and IHC assays with Ventana-D5F3 antibody. Fourteen cases with atypical and negative FISH results with the current criteria and positive IHC results were analyzed with targeted next-generation sequencing (NGS).ResultsOf the 3128 cases tested, 228 (7.3%) and 214 (6.8%) were ALK positive by IHC and FISH, respectively. Fourteen cases with negative and atypical FISH results all demonstrated IHC positivity. Of 2991 cases, eight (0.27%) with negative FISH results demonstrated echinoderm microtubule associated protein like 4 gene (EML4)-ALK fusions revealed by targeted NGS, and the relative abundance of fusion ranged from 0.9% to 46.8%. Three of 2991 cases (0.1%) did not exhibit any type of ALK fusions. In addition, two patients showed an isolated 5′ side signal and targeted NGS revealed two novel ALK partner genes, baculoviral IAP repeat containing 6 gene (BIRC6) and phosphatidylinositol binding clathrin assembly protein gene (PICALM). One patient showed an isolated and attenuated 3′ red signal and demonstrated a novel translocation partner with CCAAT/enhancer binding protein zeta gene (CEBPZ). Of all the patients, four received crizotinib treatment and demonstrated partial responses at the end of follow-up.ConclusionsOur study showed that patients with negative and atypical ALK FISH patterns may have positive results for IHC testing and harbor the translocation partners of EML4 or other genes. Therefore, additional testing with NGS should be conducted to explore the molecular mechanisms underlying the complicated gene rearrangement events.     

Utilization Trends and Factors Associated With ROS1 Testing Among Patients With Advanced Non–small-cell Lung Cancer in US Community Practices

BackgroundTargeted therapy for patients with non–small-cell lung cancer (NSCLC) harboring ROS proto-oncogene 1 (ROS1) rearrangements was approved in 2016. However, little is known about real-world ROS1 testing practices in United States community practice. We aimed to characterize ROS1 testing rates and identify potential barriers to ROS1 testing.Patients and MethodsFlatiron Health’s de-identified electronic health record-derived database was used to identify patients diagnosed with advanced NSCLC from July 2016 through December 2018 who received systemic treatment in a community practice setting. ROS1 and other biomarker testing was recorded. Regression analysis identified demographic and clinical characteristics associated with occurrence of ROS1 testing, longer time (≥ 25 days) from diagnosis to ROS1 result, and initiation of therapy prior to ROS1 result.ResultsAmong 11,409 patients, documented ROS1 testing rates increased during the study period in squamous (from 30% to 48%) and nonsquamous (63% to 78%) histologies. Patients who were older, male, black, or with squamous histology, higher Eastern Cooperative Oncology Group score, recurrent disease, or history of smoking were significantly less likely to be tested. Among patients not tested for ROS1, 63% were tested for other biomarkers. Use of next-generation sequencing, older age, Hispanic/Latino ethnicity, squamous histology, de novo disease, and smoking history predicted longer time to test result post-diagnosis. Patients with delayed results were 9.7 times more likely to receive treatment prior to ROS1 test result.ConclusionIn real-world practice, some patient subgroups may be less likely to receive timely ROS1 testing and to be identified for potential targeted therapy.     

Evaluation of a Dual ALK/ROS1 Fluorescent In Situ Hybridization Test in Non–Small-cell Lung Cancer

Background

Several therapeutics targets have emerged to treat patients with non–small-cell lung carcinoma (NSCLC), with numerous biomarkers available to test for treatment choices. Minimum tumor wastage is necessary to permit the analysis of every potentially relevant target. Searching for targetable ALK and ROS1 rearrangements is now mandatory in NSCLC. In the present study, we evaluated the performance of a dual ALK/ROS1 fluorescent in situ hybridization (FISH) probe that concurrently analyzed the 2 oncogenes on a same FISH slide.

ROS1-rearranged Non–small-cell Lung Cancer is Associated With a High Rate of Venous Thromboembolism: Analysis From a Phase II,Prospective, Multicenter,Two-arms Trial (METROS)

BackgroundPatients with cancer are at increased risk for venous thromboembolism (VTE), and 8% to 15% of patients with advanced non–small-cell lung cancer (NSCLC) experience a VTE event during the course of their disease. The incidence of VTE in molecularly defined NSCLC subgroups is still unclear. In this study, we investigated the incidence and the clinical correlates of VTE in patients with ROS1-rearranged NSCLC enrolled in the METROS trial (NCT02499614).Patients and MethodsThe METROS trial is a prospective phase II study designed to assess efficacy, safety, and tolerability of crizotinib in patients with pre-treated metastatic NSCLC ROS1 rearrangement (cohort A) or with MET amplification or MET exon 14 mutation (cohort B). Patients with ROS1-rearranged NSCLC enrolled within cohort A and the expansion cohort of the trial were included in the primary analysis.ResultsAmong 48 patients with ROS1-rearranged NSCLC enrolled in the METROS study, 20 (41.6%) of 48 had at least 1 VTE event. Among them, 7 (35%) of 20 patients had ≥ 2 VTE events. VTE events consisted of pulmonary embolism (46.4%), deep vein thrombosis (39.2%), renal vein thrombosis (7.1%), internal jugular thrombosis (3.5%), and peripheral inserted central catheter-related thrombosis (3.5%). VTE events occurred at disease progression in 35.7% of cases, at diagnosis in 32.1% of cases, and during chemotherapy or crizotinib in 17.8% and 14.2%, respectively.ConclusionThe incidence of VTE is 3- to 5-fold higher in patients harboring ROS1-rearrangment than previously observed for the general population with NSCLC. Larger studies are warranted to confirm our findings and determine whether the molecular profile of NSCLC should be incorporated into a risk-stratification tool and decision-making algorithm for VTE diagnosis and prophylaxis.