Project description:Tyrosine kinase fusion genes represent an important class of oncogenes associated with leukaemia and solid tumours. They are produced by translocations and other chromosomal rearrangements of a subset of tyrosine kinase genes, including ABL, PDGFRA, PDGFRB, FGFR1, SYK, RET, JAK2 and ALK. Based on recent findings, this review discusses the common mechanisms of activation of these fusion genes. Enforced oligomerization and inactivation of inhibitory domains are the two key processes that switch on the kinase domain. Activated tyrosine kinase fusions then signal via an array of transduction cascades, which are largely shared. In addition, the fusion partner provides a scaffold for the recruitment of proteins that contribute to signalling, protein stability, cellular localization and oligomerization. The expression level of the fusion protein is another critical parameter. Its transcription is controlled by the partner gene promoter, while translation may be regulated by miRNA. Several mechanisms also prevent the degradation of the oncoprotein by proteasomes and lysosomes, leading to its accumulation in cells. The selective inhibition of the tyrosine kinase activity by adenosine-5'-triphosphate competitors, such as imatinib, is a major therapeutic success. Imatinib induces remission in leukaemia patients that are positive for BCR-ABL or PDGFR fusions. Recently, crizotinib produced promising results in a subtype of lung cancers with ALK fusion. However, resistance was reported in both cases, partially due to mutations. To tackle this problem, additional levels of therapeutic interventions are suggested by the complex mechanisms of fusion tyrosine kinase activation. New approaches include allosteric inhibition and interfering with oligomerization or chaperones.
Project description:PurposeReceptor tyrosine kinase fusions in colorectal cancers are rare, but potentially therapeutically relevant. We describe clinical, molecular, and pathologic attributes of RTK fusion-associated colorectal cancer.Experimental designWe identified all cases with RTK fusions in patients with colorectal cancer seen at Dana-Farber Cancer Institute (Boston, MA) who underwent OncoPanel testing between 2013 and 2018. Clinical, histologic, and molecular features were extracted from the patient charts and molecular testing results.ResultsWe identified 12 driver oncogenic fusions in various RTKs. These fusions occurred exclusively in BRAF and RAS wild-type tumors and were enriched in right-sided and mismatch repair-deficient (MMR-D) colorectal cancers. All of the MMR-D colorectal cancers with RTK fusions were found in tumors with acquired MMR-D due to MLH1 promoter hypermethylation and one was associated with a sessile serrated polyp. Molecular profiles of MMR-D colorectal cancer with RTK fusions largely resembled BRAF V600E-mutated MMR-D colorectal cancer, rather than those secondary to Lynch syndrome. We describe two patients with fusion-associated microsatellite stable (MSS) colorectal cancer who derived clinical benefit from therapeutic targeting of their translocation. The first harbored an ALK-CAD fusion and received sequential crizotinib and alectinib therapy for a total of 7.5 months until developing an ALK L1196Q gatekeeper mutation. The second patient, whose tumor contained an ROS1-GOPC fusion, continues to benefit from entrectinib after 9 months of therapy.ConclusionsRTK fusions in colorectal cancer are a rare, but important disease subgroup that occurs in RAS and BRAF wild-type tumors. Despite enrichment in acquired MMR-D tumors, RTK fusions also occur in MSS colorectal cancer and provide an important therapeutic target.
Project description:Oncogenic gene fusions involving the 3' region of ROS1 kinase have been identified in various human cancers. In this study, we sought to characterize ROS1 fusion genes in non-small cell lung cancer (NSCLC) and establish the fusion proteins as drug targets.An NSCLC tissue microarray (TMA) panel containing 447 samples was screened for ROS1 rearrangement by FISH. This assay was also used to screen patients with NSCLC. In positive samples, the identity of the fusion partner was determined through inverse PCR and reverse transcriptase PCR. In addition, the clinical efficacy of ROS1 inhibition was assessed by treating a ROS1-positive patient with crizotinib. The HCC78 cell line, which expresses the SLC34A2-ROS1 fusion, was treated with kinase inhibitors that have activity against ROS1. The effects of ROS1 inhibition on proliferation, cell-cycle progression, and cell signaling pathways were analyzed by MTS assay, flow cytometry, and Western blotting.In the TMA panel, 5 of 428 (1.2%) evaluable samples were found to be positive for ROS1 rearrangement. In addition, 1 of 48 patients tested positive for rearrangement, and this patient showed tumor shrinkage upon treatment with crizotinib. The patient and one TMA sample displayed expression of the recently identified SDC4-ROS1 fusion, whereas two TMA samples expressed the CD74-ROS1 fusion and two others expressed the SLC34A2-ROS1 fusion. In HCC78 cells, treatment with ROS1 inhibitors was antiproliferative and downregulated signaling pathways that are critical for growth and survival.ROS1 inhibition may be an effective treatment strategy for the subset of patients with NSCLC whose tumors express ROS1 fusion genes.
Project description:Rearrangements, or gene fusions, involving the ETS family of transcription factors are common driving events in both prostate cancer and Ewing sarcoma. These rearrangements result in pathogenic expression of the ETS genes and trigger activation of transcriptional programs enriched for invasion and other oncogenic features. Although ETS gene fusions represent intriguing therapeutic targets, transcription factors, such as those comprising the ETS family, have been notoriously difficult to target. Recently, preclinical studies have demonstrated an association between ETS gene fusions and components of the DNA damage response pathway, such as PARP1, the catalytic subunit of DNA protein kinase (DNAPK), and histone deactylase 1 (HDAC1), and have suggested that ETS fusions may confer sensitivity to inhibitors of these DNA repair proteins. In this review, we discuss the role of ETS fusions in cancer, the preclinical rationale for targeting ETS fusions with inhibitors of PARP1, DNAPK, and HDAC1, as well as ongoing clinical trials targeting ETS gene fusions.
Project description:BackgroundReceptor tyrosine kinases (RTKs) are a class of tyrosine kinases that regulate cell-to-cell communication and control a variety of complex biological functions. Dysregulation of RTK signaling partly due to chromosomal rearrangements leads to novel tyrosine kinase fusion oncoproteins that are possibly driver alterations to cancers. Targeting some RTK fusions with specific tyrosine kinases inhibitors (TKIs) is an effective therapeutic strategy across a spectrum of RTK fusion-related cancers. However, there is still a paucity of extensive RTK fusion investigations in breast cancer. This study aims to characterize RTK fusions in Chinese breast cancer patients.MethodsAn in-house DNA sequencing database of 1440 Chinese breast cancer patients with a capture-based panel (520 gene or 108 gene-panel) was thoroughly reviewed. A total of 2,229 samples including 1,045 tissues and 1,184 plasmas were analyzed. RTK fusion was defined as an in-frame fusion with the tyrosine kinase domain of the RTK completely retained. Concomitant mutations were also analyzed and tumor mutational burden (TMB) was calculated. Patients' clinical characteristics were retrieved from case records.ResultsA total of 30 RTK fusion events were identified from 27 breast cancer patients with a prevalence of 1.875%%. FGFR2 fusions were seen the most commonly (n=7), followed by RET (n=5), ROS1 (n=3), NTRK3 (n=3), BRAF (n=2), and NTRK1 (n=2). Other RTK fusions including ALK, EGFR, FGFR1, FGFR3, MET, and NTRK2 were identified in one patient each. A total of 27 unique resultant fusion proteins (22 with a novel partner) were discovered including 19 intrachromosomal rearrangements and 8 interchromosomal ones. Twenty-one fusions had the tyrosine kinase domain in-frame fused with a partner gene and six were juxtaposed with an intergenic space. Among the 27 fusions, FGFR2-WDR11 (E17: intergenic) (n=3) and ETV6-NTRK3 (E5:E15) (n=2) occurred recurrently. Of note, the normalized abundance of RTK fusion (fusion AF/max AF) correlated negatively with TMB (r=-0.48, P=0.017). Patients with TMB < 8 (Mutations/Mb) displayed a higher fusion abundance than those with TMB ≥ 8 (Mutations/Mb) (P=0.025). Moreover, CREBBP mutation only co-occurred with FGFR2 fusion (P=0.012), while NTRK3 fusion and TP53 mutation were mutually exclusive (P=0.019).ConclusionThis is the first study comprehensively delineating the prevalence and spectrum of RTK fusions in Chinese breast cancers. Further study is ongoing to identify the enriched subpopulation who may benefit from RTK fusion inhibitors.
Project description:Cholangiocarcinoma, also known as bile duct cancer, is the second most common primary hepatic carcinoma with a median survival of less than 2 years. The molecular mechanisms underlying the development of this disease are not clear. To survey activated tyrosine kinases signaling in cholangiocarcinoma, we employed immunoaffinity profiling coupled to mass spectrometry and identified DDR1, EPHA2, EGFR, and ROS tyrosine kinases, along with over 1,000 tyrosine phosphorylation sites from about 750 different proteins in primary cholangiocarcinoma patients. Furthermore, we confirmed the presence of ROS kinase fusions in 8.7% (2 out of 23) of cholangiocarcinoma patients. Expression of the ROS fusions in 3T3 cells confers transforming ability both in vitro and in vivo, and is responsive to its kinase inhibitor. Our data demonstrate that ROS kinase is a promising candidate for a therapeutic target and for a diagnostic molecular marker in cholangiocarcinoma. The identification of ROS tyrosine kinase fusions in cholangiocarcinoma, along with the presence of other ROS kinase fusions in lung cancer and glioblastoma, suggests that a more broadly based screen for activated ROS kinase in cancer is warranted.
Project description:BackgroundWhile targeted therapies have transformed the treatment landscape of oncogene-addicted non-small cell lung cancer (NSCLC), the influence of sex on treatment outcomes remains insufficiently understood.ObjectivesThis systematic review aimed to investigate the impact of sex on clinical outcomes in patients with NSCLC harboring driver fusions treated with targeted therapies enrolled in clinical trials.Data sources and methodsA comprehensive literature search was conducted using PubMed, Embase, and relevant conference abstracts to identify phase III randomized and early clinical trials that reported sex-specific data, including progression-free survival (PFS), overall survival (OS), overall response rate, and adverse events (AEs), in patients with fusion-positive NSCLC treated with tyrosine kinase inhibitors (TKIs).ResultsThis review involved 10 studies reporting PFS data and 3 studies with OS data, focusing on first-line treatments for ALK fusion (9 studies) and RET fusion-positive (1 study) NSCLC. Pooled analysis of hazard ratios (HRs) for PFS and OS in ALK inhibitors trials revealed no significant differences in survival outcomes based on sex. Additionally, none of the studies provided data on sex-based differences in response rates or toxicities, highlighting a significant knowledge gap regarding the impact of sex on secondary outcomes in targeted therapy.ConclusionThis review found no significant sex-related differences in survival outcomes among patients treated with ALK inhibitors. However, the lack of data on sex-specific response and toxicity emphasizes the need for future research to better understand the role of sex in modulating treatment outcomes and treatment decisions with TKIs.
Project description:Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) tyrosine kinase inhibitors (TKIs) have achieved remarkable clinical progress in the treatment of non-small-cell lung cancer; however, resistance has limited their therapeutic efficacy. Therefore, understanding the mechanisms of VEGF-TKI and ICI resistance will help to develop effective treatment strategies for patients with advanced NSCLC. Our results suggested that treatment with VEGFR2-TKIs upregulated ADRB2 expression in NSCLC cells. Propranolol, a common ADRB2 antagonist, significantly enhanced the therapeutic effect of VEGFR2-TKIs by inhibiting the ADRB2 signaling pathway in NSCLC cells in vitro and in vivo. Mechanically, the treatment-induced ADRB2 upregulation and the enhancement of ADRB2/VEGFR2 interaction caused resistance to VEGFR2-TKIs in NSCLC. And the inhibition of the ADRB2/CREB/PSAT1 signaling pathway sensitized cells to VEGFR2-TKIs. We demonstrated that ADRB2 signaling is crucial in mediating resistance to VEGFR2-TKIs and provided a novel promising combinatory approach to enhance the antitumor effect of VEGFR2-TKIs in NSCLC combining with propranolol.
Project description:Selective tropomyosin receptor kinase (TRK) inhibitors are approved targeted therapies for patients with solid tumors harboring a neurotrophic tyrosine receptor kinase (NTRK) gene fusion. Country-specific estimates of NTRK gene fusion frequency, and knowledge on the characteristics of affected patients, are limited. We identified patients with histologically-confirmed papillary thyroid cancer (PTC) from Finland's Auria Biobank. TRK protein expression was determined by pan-TRK immunohistochemistry. Immuno-stained tumor samples were scored by a certified pathologist. Gene fusions and other co-occurring gene alterations were identified by next generation sequencing. Patient characteristics and vital status were determined from linked hospital electronic health records (EHRs). Patients were followed from 1 year before PTC diagnosis until death. 6/389 (1.5%) PTC patients had an NTRK gene fusion (all NTRK3); mean age 43.8 years (and none had comorbidities) at PTC diagnosis. Gene fusion partners were EML4 (n = 3), ETV6 (n = 2), and RBPMS (n = 1). Of 3/6 patients with complete EHRs, all received radioactive iodine ablation only and were alive at end of follow-up (median observation, 9.12 years). In conclusion, NTRK gene fusion is infrequent in patients with PTC. Linkage of biobank samples to EHRs is feasible in describing the characteristics and outcomes of patients with PTC and potentially other cancer types.