NTRK Gene Fusions in Non-Small-Cell Lung Cancer: Real-World Screening Data of 1068 Unselected Patients

(1) Background: The main objectives of our study are (i) to determine the prevalence of NTRK (neurotrophic tyrosine kinase) fusions in a routine diagnostic setting in NSCLC (non-small cell lung cancer) and (ii) to investigate the feasibility of screening approaches including immunohistochemistry (IHC) as a first-line test accompanied by fluorescence in situ hybridization (FISH) and RNA-(ribonucleic acid-)based next-generation sequencing (RNA-NGS). (2) Methods: A total of 1068 unselected consecutive patients with NSCLC were screened in two scenarios, either with initial IHC followed by RNA-NGS (n = 973) or direct FISH testing (n = 95). (3) Results: One hundred and thirty-three patients (14.8%) were IHC positive; consecutive RNA-NGS testing revealed two patients (0.2%) with NTRK fusions (NTRK1-EPS15 (epidermal growth factor receptor pathway substrate 15) and NTRK1-SQSTM1 (sequestosome 1)). Positive RNA-NGS was confirmed by FISH, and NTRK-positive patients benefited from targeted treatment. All patients with direct FISH testing were negative. RNA-NGS- or FISH-positive results were mutually exclusive with alterations in EGFR (epidermal growth factor receptor), ALK (anaplastic lymphoma kinase), ROS1 (ROS proto-oncogene 1), BRAF (proto-oncogene B-Raf), RET (rearranged during transfection) or KRAS (kirsten rat sarcoma viral oncogene). Excluding patients with one of these alterations raised the prevalence of NTRK-fusion positivity among panTrk-(tropomyosin receptor kinase-) IHC positive samples to 30.5%. (4) Conclusions: NTRK fusion-positive lung cancers are exceedingly rare and account for less than 1% of patients in unselected all-comer populations. Both RNA-NGS and FISH are suitable to determine clinically relevant NTRK fusions in a real-world setting. We suggest including panTrk-IHC in a diagnostic workflow followed by RNA-NGS. Excluding patients with concurrent molecular alterations to EGFR/ALK/ROS1/BRAF/RET or KRAS might narrow the target population.

Top-level MET gene copy number gain defines a subtype of poorly differentiated pulmonary adenocarcinomas with poor prognosis

Background

MET amplifications occur in human tumors, including non-small cell lung cancer (NSCLC). MET inhibitors have demonstrated some clinical activity in MET amplified NSCLC, presumably with a gene dose effect. However, the definition of MET positivity or MET amplification as a potential oncogenic driver is still under debate. In this study, we aimed to establish the molecular subgroup of NSCLC with the highest unequivocal MET amplification level and to describe the prevalence, and histologic and clinical phenotype of this subgroup.

Methods

A total of 373 unselected patients with NSCLC were consecutively tested for MET gene copy number (GCN) by FISH. Mean GCN, MET/CEN7 ratio and other FISH parameters were identified and correlated with morphological and molecular pathological characteristics of the tumors as well as with clinical data.

Results

Based on the variability of obtained data a top-level category of MET amplification was newly defined (>90th percentile of average GCN; ≥10 MET gene copies per tumor cell). This criterion was fulfilled in 2% of analyzed tumors. These tumors were exclusively poorly differentiated adenocarcinomas with a predominant solid subtype and pleomorphic features. Rarely, co-alterations were detected (KRAS mutation or MET exon 14 skipping mutation). In this top-level group, there were no EGFR mutations or ALK or ROS1 alterations. The most important clinical feature was a significantly shortened overall survival (HR 3.61; median OS 8.2 vs. 23.6 months). Worse prognosis did not depend on initial stage or treatment.

Conclusions

The newly defined top-level category of MET amplification in NSCLC defines a specific subgroup of pulmonary adenocarcinoma with adverse prognosis and characteristic morphological features. Lower levels of MET gene copy number seem to have probably no specific value as a prognostic or predictive biomarker.

Fibroblast growth factor receptor 1 gene amplification and protein expression in human lung cancer

BACKGROUND

Targeting fibroblast growth factor receptor 1 (FGFR1) is a potential treatment for squamous cell lung cancer (SQCLC). So far, treatment decision in clinical studies is based on gene amplification. However, only a minority of patients have shown durable response. Furthermore, former studies have revealed contrasting results regarding the impact of FGFR1 amplification and expression on patient's prognosis.

AIMS

Here, we analyzed prevalence and correlation of FGFR1 gene amplification and protein expression in human lung cancer and their impact on overall survival. MATERIALS & METHODS: FGFR1 gene amplification and protein expression were analyzed by fluorescence in situ hybridization and immunohistochemistry (IHC) in 208 SQCLC and 45 small cell lung cancers (SCLC). Furthermore, FGFR1 protein expression was analyzed in 121 pulmonary adenocarcinomas (ACs). Amplification and expression were correlated to each other, clinicopathological characteristics, and overall survival.

RESULTS

FGFR1 was amplified in 23% of SQCLC and 8% of SCLC. Amplification was correlated to males (P = .027) but not to overall survival. Specificity of immunostaining was verified by cellular CRISPR/Cas9 FGFR1 knockout. FGFR1 was strongly expressed in 9% of SQCLC, 35% of AC, and 4% of SCLC. Expression was correlated to females (P = .0187) and to the absence of lymph node metastasis in SQCLC (P = .018) with no significant correlation to overall survival. Interestingly, no significant correlation between amplification and expression was detected.

DISCUSSION

FGFR1 gene amplification does not seem to correlate to protein expression.

CONCLUSION

We believe that patient selection for FGFR1 inhibitors in clinical studies should be reconsidered. Neither FGFR1 amplification nor expression influences patient's prognosis.

miR-15a-5p regulates expression of multiple proteins in the megakaryocyte GPVI signaling pathway

Essentials The action of microRNAs (miRs) in human megakaryocyte signaling is largely unknown. Cord blood-derived human megakaryocytes (MKs) were used to test the function of candidate miRs. miR-15a-5p negatively regulated MK GPVI-mediated αIIbβ3 activation and α-granule release. miR-15a-5p acts as a potential "master-miR" regulating genes in the MK GPVI signaling pathway. SUMMARY: Background Megakaryocytes (MKs) invest their progeny platelets with proteins and RNAs. MicroRNAs (miRs), which inhibit mRNA translation into protein, are abundantly expressed in MKs and platelets. Although platelet miRs have been associated with platelet reactivity and disease, there is a paucity of information on the function of miRs in human MKs. Objective To identify MK miRs that regulate the GPVI signaling pathway in the MK-platelet lineage. Methods Candidate miRs associated with GPVI-mediated platelet aggregation were tested for functionality in cultured MKs derived from cord blood. Results An unbiased, transcriptome-wide screen in 154 healthy donors identified platelet miR-15a-5p as significantly negatively associated with CRP-induced platelet aggregation. Platelet agonist dose-response curves demonstrated activation of αIIbβ3 in suspensions of cord blood-derived cultured MKs. Overexpression and knockdown of miR-15a-5p in these MKs reduced and enhanced, respectively, CRP-induced αIIbβ3 activation but did not alter thrombin or ADP stimulation. FYN, SRGN, FCER1G, MYLK. and PRKCQ, genes involved in GPVI signaling, were identified as miR-15a-5p targets and were inhibited or de-repressed in MKs with miR-15a-5p overexpression or inhibition, respectively. Lentiviral overexpression of miR-15a-5p also inhibited GPVI-FcRγ-mediated phosphorylation of Syk and PLCγ2, GPVI downstream signaling molecules, but effects of miR-15a-5p on αIIbβ3 activation did not extend to other ITAM-signaling receptors (FcγRIIa and CLEC-2). Conclusion Cord blood-derived MKs are a useful human system for studying the functional effects of candidate platelet genes. miR-15a-5p is a potential "master-miR" for specifically regulating GPVI-mediated MK-platelet signaling. Targeting miR-15a-5p may have therapeutic potential in hemostasis and thrombosis.

FGFR3 mRNA overexpression defines a subset of oligometastatic colorectal cancers with worse prognosis

Objectives

Metastatic colorectal cancer (CRC) remains a leading cause of cancer related deaths. Patients with oligometastatic liver disease represent a clinical subgroup with heterogeneous course. Until now, biomarkers to characterize outcome and therapeutic options have not been fully established.

Methods

We investigated the prevalence of FGFR alterations in a total of 140 primary colorectal tumors and 63 liver metastases of 55 oligometastatic CRC patients. FGF receptors (FGFR1-4) and their ligands (FGF3, 4 and 19) were analyzed for gene amplifications and rearrangements as well as for RNA overexpression in situ. Results were correlated with clinico-pathologic data and molecular subtypes.

Results

Primary tumors showed FGFR1 (6.3%) and FGF3,4,19 (2.2%) amplifications as well as FGFR1 (10.1%), FGFR2 (5.5%) and FGFR3 (16.2%) overexpression. In metastases, we observed FGFR1 amplifications (4.8%) as well as FGFR1 (8.5%) and FGFR3 (14.9%) overexpression. Neither FGFR2-4 amplifications nor gene rearrangements were observed. FGFR3 overexpression was significantly associated with shorter overall survival in metastases (mOS 19.9 vs. 47.4 months, HR=3.14, p=0.0152), but not in primary CRC (HR=1.01, p=0.985). Although rare, also FGFR1 amplification was indicative of worse outcome (mOS 12.6 vs. 47.4 months, HR=8.83, p=0.00111).

Conclusions

We provide the so far most comprehensive analysis of FGFR alterations in primary and metastatic CRC. We describe FGFR3 overexpression in 15% of CRC patients with oligometastatic liver disease as a prognosticator for poor outcome. Recently FGFR3 overexpression has been shown to be a potential therapeutic target. Therefore, we suggest focusing on this subgroup in upcoming clinical trials with FGFR-targeted therapies.

Partial Response to First-Line Crizotinib in an Elderly Male Patient with ROS1 Translocation-Positive Lung Cancer

We report on a 90-year-old male patient with a ROS1-translocated adenocarcinoma of the lung who was treated with crizotinib as first-line therapy. After 11 months of treatment, we noticed complete metabolic response as measured by ¹⁸F-FDG-PET/CT scan and a partial response according to RECIST criteria. This patient indicates that ROS1 translocations are not restricted to young age, female gender and low stage. Furthermore, this case illustrates exemplarily that crizotinib therapy is effective and manageable even as first-line treatment in elderly patients with comorbidities. Based on our findings, we recommend to include elderly patients with advanced pulmonary adenocarcinomas in molecular screening approaches for ROS1 translocations.

Engagement of the Fc epsilon RI stimulates the production of IL-16 in Langerhans cell-like dendritic cells

Preferential uptake and presentation of IgE-bound allergens by epidermal Langerhans cells (LC) via the high affinity IgE receptor, FcepsilonRI, is regarded as an important mechanism in the induction of cutaneous inflammation in atopic dermatitis. Here, we show that activation of monocyte-derived LC-like dendritic cells (LLDC) through engagement of FcepsilonRI induces the expression of IL-16, a chemoattractant factor for dendritic cells, CD4+ T cells, and eosinophils. We found that ligation of FcepsilonRI on LLDC derived from atopic dermatitis patients that express high levels of FcepsilonRI increases IL-16 mRNA expression and storage of intracellular IL-16 protein and enhances the secretion of mature IL-16 in a biphasic manner. An early release of IL-16 (peak at 4 h) is independent of protein synthesis, while a more delayed release (peak at 12 h) requires protein synthesis and occurs subsequent to the induction of IL-16 mRNA and intracellular accumulation of pro-IL-16. There was evidence that LLDC use caspase-1 to process IL-16, as inhibition of caspase-1, but not of caspase-3, partially prevented the release of IL-16 in response to ligation of FcepsilonRI. In an in vivo model of IgE-dependent LC activation, the atopy patch test, positive skin reactions were also associated with the induction of IL-16 in epidermal dendritic cells. These data indicate that IL-16 released from LC after allergen-mediated activation through FcepsilonRI may link IgE-driven and cellular inflammatory responses in diseases such as atopic dermatitis.