Investigation of neurotrophic tyrosine kinase receptor 1 fusions and neurotrophic tyrosine kinase receptor family expression in non-small-cell lung cancer and sensitivity to AZD7451 in vitro

ETV6-NTRK2 Fusion in a Patient With Metastatic Pulmonary Atypical Carcinoid Successfully Treated With Entrectinib: A Case Report and Review of the Literature

Pulmonary atypical carcinoid (AC) is an extremely rare neuroendocrine tumor. The neurotrophic tropomyosin receptor kinase (NTRK) fusions are reported in only 0.5% of nonsmall cell lung cancer, and are more rare in AC with only one previously reported case. Currently, there is little established evidence on the optimal therapeutic strategies and prognosis for advanced cases. We present a female patient with metastatic AC after complete resection. Due to low expression of somatostatin receptor in this case, somatostatin analogs and peptide receptor radionuclide therapy were not available. After pursuing other alternative treatments, including chemotherapy (ie, carboplatin, etoposide, capecitabine, temozolomide, and paclitaxel), everolimus, and atezolizumab, she returned with significant progression, including innumerable subcutaneous nodules, left pleura metastasis, multiple bone metastases, and brain metastases. New biopsy analysis revealed an ETV6-NTRK2 fusion. She was immediately administered the first-generation tropomyosin receptor kinase inhibitor entrectinib at a dose of 600 mg q.d. A subsequent month of treatment resulted in a complete response in all of the metastatic lung lesions. To date, she has maintained sustained benefit for at least 1 year from initiation of entrectinib. Here, we present the first case of a female patient with metastatic AC harboring the ETV6-NTRK2 fusion, and successfully treated with entrectinib, providing evidence for the application of entrectinib in patients with NTRK-positive AC, and underscoring the critical role of molecular profiling for such cases.

Meta-analysis of microarray data to determine gene indicators involved in cisplatin resistance in non-small cell lung cancer

BACKGROUND

Lung cancer is a major cause of cancer-related mortality worldwide, with a 5-year survival rate of approximately 22%. Cisplatin is one of the standard first-line chemotherapeutic agents for non-small cell lung cancer (NSCLC), but its efficacy is often limited by the development of resistance. Despite extensive research on the molecular mechanisms of chemoresistance, the underlying causes remain elusive and complex.

AIMS

We analyzed three microarray datasets to find the gene signature and key pathways related to cisplatin resistance in NSCLC.

METHODS AND RESULTS

We compared the gene expression of sensitive and resistant NSCLC cell lines treated with cisplatin. We found 274 DEGs, including 111 upregulated and 163 downregulated genes, in the resistant group. Gene set enrichment analysis showed the potential roles of several DEGs, such as TUBB2B, MAPK7, TUBAL3, MAP2K5, SMUG1, NTHL1, PARP3, NTRK1, G6PD, PDK1, HEY1, YTHDF2, CD274, and MAGEA1, in cisplatin resistance. Functional analysis revealed the involvement of pathways, such as gap junction, base excision repair, central carbon metabolism, and Notch signaling in the resistant cell lines.

CONCLUSION

We identified several molecular factors that contribute to cisplatin resistance in NSCLC cell lines, involving genes and pathways that regulate gap junction communication, DNA damage repair, ROS balance, EMT induction, and stemness maintenance. These genes and pathways could be targets for future studies to overcome cisplatin resistance in NSCLC.

Brazilian Expert Consensus for NTRK Gene Fusion Testing in Solid Tumors

Oncogenic neurotrophic tropomyosin receptor kinase gene fusions occur in less than 1% of common cancers. These mutations have emerged as new biomarkers in cancer genomic profiling with the approval of selective drugs against tropomyosin receptor kinase fusion proteins. Nevertheless, the optimal pathways and diagnostic platforms for this biomarker's screening and genomic profiling have not been defined and remain a subject of debate. A panel of national experts in molecular cancer diagnosis and treatment was convened by videoconference and suggested topics to be addressed in the literature review. The authors proposed a testing algorithm for oncogenic neurotrophic tropomyosin receptor kinase gene fusion screening and diagnosis for the Brazilian health system. This review aims to discuss the latest literature evidence and international consensus on neurotrophic tropomyosin receptor kinase gene fusion diagnosis to devise clinical guidelines for testing this biomarker. We propose an algorithm in which testing for this biomarker should be requested to diagnose advanced metastatic tumors without known driver mutations. In this strategy, Immunohistochemistry should be used as a screening test followed by confirmatory next-generation sequencing in immunohistochemistry-positive cases.

Expert consensus on the diagnosis and treatment of NTRK gene fusion solid tumors in China

Gene fusions can drive tumor development for multiple types of cancer. Currently, many drugs targeting gene fusions are being approved for clinical application. At present, tyrosine receptor kinase (TRK) inhibitors targeting neurotrophic tyrosine receptor kinase (NTRK) gene fusions are among the first "tumor agnostic" drugs approved for pan-cancer use. Representative TRK inhibitors, including larotrectinib and entrectinib, have shown high efficacy for many types of cancer. At the same time, several second-generation drugs designed to overcome first-generation drug resistance are undergoing clinical development. Due to the rarity of NTRK gene fusions in common cancer types and technical issues regarding the complexity of fusion patterns, effectively screening patients for TRK inhibitor treatment in routine clinical practice is challenging. Different detection methods including immunohistochemistry, fluorescence in situ hybridization, reverse transcription-polymerase chain reaction, and (DNA and/or RNA-based) next-generation sequencing have pros and cons. As such, recommending suitable tests for individual patients and ensuring the quality of tests is essential. Moreover, at present, there is a lack of systematic review for the clinical efficacy and development status of first- and second-generation TRK inhibitors. To resolve the above issues, our expert group has reached a consensus regarding the diagnosis and treatment of NTRK gene fusion solid tumors, aiming to standardize clinical practice with the goal of benefiting patients with NTRK gene fusions treated with TRK inhibitors.

Toward in vivo proof of binding of 18F-labeled inhibitor [18F]TRACK to peripheral tropomyosin receptor kinases

BACKGROUND

Tropomyosin receptor kinases (TrkA, TrkB, TrkC) are a family of tyrosine kinases primarily expressed in neuronal cells of the brain. Identification of oncogenic alterations in Trk expression as a driver in multiple tumor types has increased interest in their role in human cancers. Recently, first- and second-generation ¹¹C and ¹⁸F-labeled Trk inhibitors, e.g., [¹⁸F]TRACK, have been developed. The goal of the present study was to analyze the direct interaction of [¹⁸F]TRACK with peripheral Trk receptors in vivo to prove its specificity for use as a functional imaging probe.

METHODS

In vitro uptake and competition experiments were carried out using the colorectal cancer cell line KM12. Dynamic PET experiments were performed with [¹⁸F]TRACK, either alone or in the presence of amitriptyline, an activator of Trk, entrectinib, a Trk inhibitor, or unlabeled reference compound TRACK in KM12 tumor-bearing athymic nude mice as well as B6129SF2/J and corresponding B6;129S2-Ntrk2^tm1Bbd/J mice. Western blot and immunohistochemistry experiments were done with KM12 tumors, brown adipose tissue (BAT), and brain tissue samples.

RESULTS

Uptake of [¹⁸F]TRACK was increasing over time reaching 208 ± 72% radioactivity per mg protein (n = 6/2) after 60 min incubation time. Entrectinib and TRACK competitively blocked [¹⁸F]TRACK uptake in vitro (IC₅₀ 30.9 ± 3.6 and 29.4 ± 9.4 nM; both n = 6/2). [¹⁸F]TRACK showed uptake into KM12 tumors (SUV_mean,60 min 0.43 ± 0.03; n = 6). Tumor-to-muscle ratio reached 0.9 (60 min) and 1.2 (120 min). In TrkB expressing BAT, [¹⁸F]TRACK uptake reached SUV_mean,60 min 1.32 ± 0.08 (n = 7). Activation of Trk through amitriptyline resulted in a significant radioactivity increase of 21% in KM12 tumor (SUV_mean,60 min from 0.53 ± 0.01 to 0.43 ± 0.03; n = 6; p < 0.05) and of 21% in BAT (SUV_mean,60 min from 1.32 ± 0.08; n = 5 to 1.59 ± 0.07; n = 6; p < 0.05) respectively. Immunohistochemistry showed TrkB > TrkA expression on BAT fat cells, but TrkA > TrkB in whole brain. WB analysis showed sevenfold higher TrkB expression in BAT versus KM12 tumor tissue.

CONCLUSION

The present data show that radiotracer [¹⁸F]TRACK can target peripheral Trk receptors in human KM12 colon cancer as well as brown adipose tissue as confirmed through in vitro and in vivo blocking experiments. Higher TrkB versus TrkA protein expression was detected in brown adipose tissue of mice confirming a peripheral functional role of brain-derived neurotrophic factor in adipose tissue.

Immunohistochemistry as a screening tool for NTRK gene fusions: results of a first Belgian ring trial

A Belgian ring trial for pan-TRK immunohistochemistry (IHC) staining was organised to harmonise pan-TRK IHC staining protocols and interpretation. As a reference method, the VENTANA pan-TRK Assay (clone EPR17341) on the Benchmark Ultra platform was selected. Six samples were selected: 2 negative, 2 fusion positive and 2 samples with wild-type endogenous TRK expression. Each participating laboratory stained the slides using their routine pan-TRK IHC and reported their results. In addition, they were asked to return one TRK-stained slide from each case. The coordinating lab evaluated these slides, compared them with the reference method and scored them. Two clones were used during the ring trial: A7H6R (Cell Signaling) and EPR17341 (Abcam/Ventana). Seven protocols achieved a sufficient performance mark, and three labs were advised to further optimise the protocol. Interpretation of pan-TRK IHC proved to be challenging in cases with physiological TRK expression. In addition, depending on the NTRK fusion partner, the staining can vary strongly in both intensity and staining pattern. Labs using the Ventana ready-to-use system based on the EPR17341 clone and using the recommended protocol settings scored best. However, given some small optimisation, all labs scored well on the technical staining and the succeeding evaluation.

Pulmonary Large-Cell Neuroendocrine Carcinoma: Therapeutic Challenges and Opportunities

Pulmonary large cell neuroendocrine carcinoma (P-LCNEC) is a rare, poorly differentiated, non-small cell malignancy within the spectrum of neuroendocrine tumors (NETs) of the lung. Despite sharing several similarities with small cell lung cancer (SCLC) in their clinical, immunohistopathological, genomic, and prognostic features, it is a distinct and biologically heterogeneous entity with challenging diagnostic and therapeutic requirements. Given the lack of prospective, randomized data to guide management, it is common practice to pursue thoracic surgery for resectable tumors according to the guidelines for non-small cell lung cancer (NSCLC) and implement systemic chemotherapy as early as at stage I, similar to the treatment of SCLC. However, important issues, such as the optimal timing and combination of therapeutic modalities, the most effective type of chemotherapy for advanced-stage disease, and the benefit from prophylactic cranial irradiation, remain debated. Accumulating evidence from retrospective, molecular profiling studies supports the existence of at least two P-LCNEC subtypes, most notably a SCLC-like and a NSCLC-like phenotype, which presumably underlie the observed differential sensitivity to platinum-based regimens and warrant further validation as predictive biomarkers of efficacy. Furthermore, several potentially actionable, driver molecular alterations have been identified, offering implications for personalized treatment approaches, including targeted therapies and immunotherapy. The current review discusses open questions on the diagnosis and management of P-LCNEC, as well as recent advances in its genomic and transcriptomic characterization that create promising therapeutic opportunities.

NT-3/TrkC Axis Contributes to the Perineural Invasion and the Poor Prognosis in Human Salivary Adenoid Cystic Carcinoma

The present study was aimed to investigate the role and mechanism of neurotrophin-3 (NT-3) and its specific receptor tropomyosin receptor kinase C (TrkC) in the perineural invasion (PNI) process of the salivary adenoid cystic carcinoma (SACC). The co-cultured system between SACC cells and Schwann cells (SCs) was employed to detect the expression of NT-3 and TrkC. The results of ELISA, qRT-PCR and western blot showed that NT-3 was noticeably elevated in the co-cultured SACC-83 cells, while TrkC was increased in the co-cultured SCs. The results of scratch wound healing, migration, and 3D co-culture assays showed that the directional migration abilities of the co-cultured SACC-83 cells and SCs were significantly increased. Under the stimulation of NT-3, the directional motor ability of SACC-83 cells and SCs was significantly improved, and the apoptosis of SACC-83 cells and SCs were obviously inhibited. In addition, blocking TrkC by its specific inhibitor AZD7451 could significantly inhibit these effects. Immunohistochemistry staining showed that the positive expression of NT-3 (88.5%) and TrkC (92.3%) was significantly correlated with the PNI in SACC specimens (P < 0.05). Additionally, the high expression of NT-3 was significantly associated with the poor prognosis of SACC patients (P < 0.05). The present study indicated that NT-3/TrkC axis contributed to the PNI progression and the poor prognosis of SACC via regulating the interaction between SACC cells and SCs. Interruption of the interaction between SACC cells and SCs by blocking the NT-3/TrkC axis might be an effective strategy for anti-PNI therapy in SACC.

ESMO recommendations on the standard methods to detect NTRK fusions in daily practice and clinical research

BACKGROUND

NTRK1, NTRK2 and NTRK3 fusions are present in a plethora of malignancies across different histologies. These fusions represent the most frequent mechanism of oncogenic activation of these receptor tyrosine kinases, and biomarkers for the use of TRK small molecule inhibitors. Given the varying frequency of NTRK1/2/3 fusions, crucial to the administration of NTRK inhibitors is the development of optimal approaches for the detection of human cancers harbouring activating NTRK1/2/3 fusion genes.

MATERIALS AND METHODS

Experts from several Institutions were recruited by the European Society for Medical Oncology (ESMO) Translational Research and Precision Medicine Working Group (TR and PM WG) to review the available methods for the detection of NTRK gene fusions, their potential applications, and strategies for the implementation of a rational approach for the detection of NTRK1/2/3 fusion genes in human malignancies. A consensus on the most reasonable strategy to adopt when screening for NTRK fusions in oncologic patients was sought, and further reviewed and approved by the ESMO TR and PM WG and the ESMO leadership.

RESULTS

The main techniques employed for NTRK fusion gene detection include immunohistochemistry, fluorescence in situ hybridization (FISH), RT-PCR, and both RNA-based and DNA-based next generation sequencing (NGS). Each technique has advantages and limitations, and the choice of assays for screening and final diagnosis should also take into account the resources and clinical context.

CONCLUSION

In tumours where NTRK fusions are highly recurrent, FISH, RT-PCR or RNA-based sequencing panels can be used as confirmatory techniques, whereas in the scenario of testing an unselected population where NTRK1/2/3 fusions are uncommon, either front-line sequencing (preferentially RNA-sequencing) or screening by immunohistochemistry followed by sequencing of positive cases should be pursued.

Targeting tropomyosin receptor kinase for cancer therapy

NTRKs and their expression product tropomyosin receptor kinases (Trks) are widely distributed in mammals. While neural growth factor (NGF)-induced normal Trk activation plays a key role in nerve growth, NTRK alternations occurring in tumor cells were highly correlated to tumor progression and invasion. Recent clinical data from several pan-Trk inhibitors have demonstrated potential and broad applications in various cancers. This intrigues us to summarize the development of inhibitors targeting Trks with different mechanisms of action and their applications in cancer therapy. We believe that this perspective would be of great help in investigating novel anticancer drugs with better therapeutic index.

β-catenin/TCF activity regulates IGF-1R tyrosine kinase inhibitor sensitivity in colon cancer

The availability of large-scale drug screening data on cell line panels provides a unique opportunity to identify predictive biomarkers for targeted drug efficacy. Analysis of diverse drug data on ~990 cancer cell lines revealed enhanced sensitivity of insulin-like growth factor 1 receptor/ Insulin Receptor (IGF-1R/IR) tyrosine kinase inhibitors (TKIs) in colon cancer cells. Interestingly, β-catenin/TCF(T cell factor)-responsive promoter activity exhibited a significant positive association with IGF-1R/IR TKI response, while the mutational status of direct upstream genes, such as CTNNB1 and APC, was not significantly associated with the response. The β-catenin/TCF activity high cell lines express components of IGF-1R/IR signaling more than the low cell lines explaining their enhanced sensitivity against IGF-1R/IR TKI. Reinforcing β-catenin/TCF responsive promoter activity by introducing CTNNB1 gain-of-function mutations into IGF-1R/IR TKI-resistant cells increased the expression and activity of IGF-1R/IR signaling components and also sensitized the cells to IGF-1R/IR TKIs in vitro and in vivo. Analysis of TCGA data revealed that the stronger β-catenin/TCF responsive promoter activity was associated with higher IGF-1R and IGF2 transcription in human colon cancer specimens as well. Collectively, compared to the mutational status of upstream genes, β-catenin/TCF responsive promoter activity has potential to be a stronger predictive positive biomarker for IGF-1R/IR TKI responses in colon cancer cells. The present study highlights the potential of transcriptional activity as therapeutic biomarkers for targeted therapies, overcoming the limited ability of upstream genetic mutations to predict responses.

Tropomyosin receptor kinase: a novel target in screened neuroendocrine tumors

Tropomyosin receptor kinase (Trk) inhibitors are investigated as a novel targeted therapy in various cancers. We investigated the in vitro effects of the pan-Trk inhibitor GNF-5837 in human neuroendocrine tumor (NET) cells. The human neuroendocrine pancreatic BON1, bronchopulmonary NCI-H727 and ileal GOT1 cell lines were treated with GNF-5837 alone and in combination with everolimus. Cell viability decreased in a time- and dose-dependent manner in GOT1 cells in response to GNF-5837 treatment, while treatment in BON1 and NCI-H727 cells showed no effect on cellular viability. Trk receptor expression determined GNF-5837 sensitivity. GNF-5837 caused downregulation of PI3K-Akt-mTOR signaling, Ras-Raf-MEK-ERK signaling, the cell cycle and increased apoptotic cell death. The combinational treatment of GNF-5837 with everolimus showed a significant enhancement in inhibition of cell viability vs single substance treatments, due to a cooperative PI3K-Akt-mTOR and Ras-Raf-MEK-ERK pathway downregulation, as well as an enhanced cell cycle component downregulation. Immunohistochemical staining for Trk receptors were performed using a tissue microarray containing 107 tumor samples of gastroenteropancreatic NETs. Immunohistochemical staining with TrkA receptor and pan-Trk receptor antibodies revealed a positive staining in pancreatic NETs in 24.2% (8/33) and 33.3% (11/33), respectively. We demonstrated that the pan-Trk inhibitor GNF-5837 has promising anti-tumoral properties in human NET cell lines expressing the TrkA receptor. Immunohistochemical or molecular screening for Trk expression particularly in pancreatic NETs might serve as predictive marker for molecular targeted therapy with Trk inhibitors.

Integrative proteomic and transcriptomic analysis provides evidence for TrkB (NTRK2) as a therapeutic target in combination with tyrosine kinase inhibitors for non-small cell lung cancer

While several molecular targets have been identified for adenocarcinoma (ACA) of the lung, similar drivers with squamous cell carcinoma (SCC) are sparse. We compared signaling pathways and potential therapeutic targets in lung SCC and ACA tumors using reverse phase proteomic arrays (RPPA) from two independent cohorts of resected early stage NSCLC patients: a testing set using an MDACC cohort (N=140) and a validation set using the Cancer Genome Atlas (TCGA) cohorts. We identified multiple potentially targetable proteins upregulated in SCC, including NRF2, Keap1, PARP, TrkB, and Chk2. Of these potential targets, we found that TrkB also had significant increases in gene expression in SCC as compared to adenocarcinoma. Thus, we next validated the upregulation of TrkB both in vitro and in vivo and found that it was constitutively expressed at high levels in a subset of SCC cell lines. Furthermore, we found that TrkB inhibition suppressed tumor growth, invasiveness and sensitized SCC cells to tyrosine kinase EGFR inhibition in a cell-specific manner.

Infantile NTRK-associated Mesenchymal Tumors

Pediatric fibroblastic/myofibroblastic lesions are a relatively common group of tumors with varying morphologies, for which the molecular mechanisms are becoming increasingly well characterized. Congenital infantile fibrosarcoma (CIFS), perhaps the most well studied of these lesions is characterized by a recurrent ETV6-NTRK3 gene fusion. However, a notable subset of locally aggressive congenital/infantile soft tissue lesions with similar morphologic features to CIFS, have not to-date, shown evidence of any canonical molecular aberration. We describe 6 patients with mesenchymal tumors composed of infiltrative fibroblastic/myofibroblastic tumor cells and showing a morphologic spectrum of features much analogous to that previously described in CIFS but without ETV6 fusion transcripts. These tumors lacked a uniform immunoprofile, but showed variable expression of CD34, S100, smooth muscle actin, and CD30. All patients first developed a mass in infancy (≤2 months of age). Using next-generation DNA sequencing, TMP3-NTRK1 fusions were identified in 4 cases, an LMNA-NTRK1 fusion in one case, and a variant EML4-NTRK3 fusion in one case. Similar to infantile fibrosarcoma, these tumors were locally aggressive (with local recurrences if incompletely excised) and rarely metastasized (lung metastases in one patient). Proper identification of these tumors including investigation for NTRK family gene rearrangements is essential for diagnostic accuracy, as well as for clinical management decisions. Given the morbidity associated with radical resection of large soft tissue tumors, children with unresectable, recurrent, and/or metastatic disease may benefit from treatment with NTRK targeted therapies.

Exploiting polypharmacology for improving therapeutic outcome of kinase inhibitors (KIs): An update of recent medicinal chemistry efforts

Polypharmacology has been increasingly advocated for the therapeutic intervention in complex pathological conditions, exemplified by cancer. Although kinase inhibitors (KIs) have revolutionized the treatment for certain types of malignancies, some major medical needs remain unmet due to the relentless advance of drug resistance and insufficient efficacy of mono-target KIs. Hence, "multiple targets, multi-dimensional activities" represents an emerging paradigm for innovative anti-cancer drug discovery. Over recent years, considerable leaps have been made in pursuit of kinase-centric polypharmacological anti-cancer therapeutics, providing avenues to tackling the limitation of mono-target KIs. In the review, we summarize the clinically important mechanisms inducing KI resistance and depict a landscape of recent medicinal chemistry efforts on exploring kinase-centric polypharmacological anti-cancer agents that targeting multiple cancer-related processes. In parallel, some inevitable challenges are emphasized for the sake of more accurate and efficient drug discovery in the field.

New targets bring hope in squamous cell lung cancer: neurotrophic tyrosine kinase gene fusions

Neurotrophic tyrosine kinase genes encode for the Trk-family proteins TrkA, TrkB, and TrkC, which have an important role in the development of the nervous system; however, they have been identified as oncogenic fusions in solid tumors (NTK-1, NTRK-2, and NTRK-3) and are associated with poor survival in lung cancer. These three new fusions can be detected by fluorescent in situ hybridization or next-generation sequencing in less than 5% of the lung tumors. There are several ongoing clinical trials of NTRK oncogenes in lung cancer and other tumors. The agents entrectinib (RXDX-101), a multi-kinase small molecule inhibitor that selectively inhibits NTRK1, NTRK2, and NTRK3, ROS1 and ALK, and LOXO-101, an ATP-competitive pan-NTRK inhibitor, have shown responses in patients with lung cancer with an acceptable toxicity profile. Although these oncogenic fusions are not very prevalent, the high prevalence of lung cancer makes these findings very relevant and suggests the feasibility of these oncogenes as targets in lung cancer. New data from Ozono and collaborators presented in this issue suggest that BDNF/TrkB signal promotes proliferating migratory and invasive phenotypes and cellular plasticity in squamous cell carcinoma (SCC) of the lung but that it also represents a druggable target that may bring hope to squamous lung cancer patients.

Expanded molecular interrogation for potential actionable targets in non-squamous non-small cell lung cancer

The advent of targeted therapies has established new standards of care for defined molecular subsets of non-small cell lung cancer (NSCLC). Not only has this led to significant changes in the routine clinical management of lung cancer e.g., multiplexed genomic testing, but it has provided important principles and benchmarks for determining "actionability". At present, the clinical paradigms are most evolved for EGFR mutations and ALK rearrangements, where multiple randomized phase III trials have determined optimal treatment strategies in both treatment naïve and resistant settings. However, this may not always be feasible with low prevalence alterations e.g., ROS1 and BRAF mutations. Another emerging observation is that not all targets are equally "actionable", necessitating a rigorous preclinical, clinical and translational framework to prosecute new targets and drug candidates. In this review, we will cover the role of targeted therapies for NSCLC harbouring BRAF, MET, HER2 and RET alterations, all of which have shown promise in non-squamous non-small cell lung cancer (ns-NSCLC). We further review some early epigenetic targets in NSCLC, an area of emerging interest. With increased molecular segmentation of lung cancer, we discuss the upcoming challenges in drug development and implementation of precision oncology approaches, especially in light of the complex and rapidly evolving therapeutic landscape.

Targeting NTRK fusion in non-small cell lung cancer: rationale and clinical evidence

In the era of personalized medicine, the identification of targetable genetic alterations represented a major step forward in anticancer therapy. NTRK rearrangements represent the molecular driver of a subset of solid tumors, including 3% of non-small-cell lung cancers (NSCLCs). Preliminary data indicate that molecularly selected NSCLC patients harboring NTRK fusions derive an unprecedented clinical benefit from Trk-directed targeted therapies. The aim of this review is to describe the molecular biology of NTRK signaling pathway and to summarize the preclinical data on novel Trk inhibitors, touching upon the clinical development of these inhibitors for the treatment of advanced NSCLC, which have already shown encouraging anticancer activity and acceptable safety profile in early phase I clinical trials.

Pediatric, Adolescent, and Young Adult Thyroid Carcinoma Harbors Frequent and Diverse Targetable Genomic Alterations, Including Kinase Fusions

BACKGROUND

Thyroid carcinoma, which is rare in pediatric patients (age 0-18 years) but more common in adolescent and young adult (AYA) patients (age 15-39 years), carries the potential for morbidity and mortality.

METHODS

Hybrid-capture-based comprehensive genomic profiling (CGP) was performed prospectively on 512 consecutively submitted thyroid carcinomas, including 58 from pediatric and AYA (PAYA) patients, to identify genomic alterations (GAs), including base substitutions, insertions/deletions, copy number alterations, and rearrangements. This PAYA data series includes 41 patients with papillary thyroid carcinoma (PTC), 3 with anaplastic thyroid carcinoma (ATC), and 14 with medullary thyroid carcinoma (MTC).

RESULTS

GAs were detected in 93% (54/58) of PAYA cases, with a mean of 1.4 GAs per case. In addition to BRAF V600E mutations, detected in 46% (19/41) of PAYA PTC cases and in 1 of 3 AYA ATC cases, oncogenic fusions involving RET, NTRK1, NTRK3, and ALK were detected in 37% (15/41) of PAYA PTC and 33% (1/3) of AYA ATC cases. Ninety-three percent (13/14) of MTC patients harbored RET alterations, including 3 novel insertions/deletions in exons 6 and 11. Two of these MTC patients with novel alterations in RET experienced clinical benefit from vandetanib treatment.

CONCLUSION

CGP identified diverse clinically relevant GAs in PAYA patients with thyroid carcinoma, including 83% (34/41) of PTC cases harboring activating kinase mutations or activating kinase rearrangements. These genomic observations and index cases exhibiting clinical benefit from targeted therapy suggest that young patients with advanced thyroid carcinoma can benefit from CGP and rationally matched targeted therapy. The Oncologist 2017;22:255-263 IMPLICATIONS FOR PRACTICE: The detection of diverse clinically relevant genomic alterations in the majority of pediatric, adolescent, and young adult patients with thyroid carcinoma in this study suggests that comprehensive genomic profiling may be beneficial for young patients with papillary, anaplastic, or medullary thyroid carcinoma, particularly for advanced or refractory cases for which clinical trials involving molecularly targeted therapies may be appropriate.

Durable Clinical Response to Entrectinib in NTRK1-Rearranged Non-Small Cell Lung Cancer

INTRODUCTION

Chromosomal rearrangements involving neurotrophic tyrosine kinase 1 (NTRK1) occur in a subset of non-small cell lung cancers (NSCLCs) and other solid tumor malignancies, leading to expression of an oncogenic TrkA fusion protein. Entrectinib (RXDX-101) is an orally available tyrosine kinase inhibitor, including TrkA. We sought to determine the frequency of NTRK1 rearrangements in NSCLC and to assess the clinical activity of entrectinib.

METHODS

We screened 1378 cases of NSCLC using anchored multiplex polymerase chain reaction (AMP). A patient with an NTRK1 gene rearrangement was enrolled onto a Phase 1 dose escalation study of entrectinib in adult patients with locally advanced or metastatic tumors (NCT02097810). We assessed safety and response to treatment.

RESULTS

We identified NTRK1 gene rearrangements at a frequency of 0.1% in this cohort. A patient with stage IV lung adenocrcinoma with an SQSTM1-NTRK1 fusion transcript expression was treated with entrectinib. Entrectinib was well tolerated, with no grade 3-4 adverse events. Within three weeks of starting on treatment, the patient reported resolution of prior dyspnea and pain. Restaging CT scans demonstrated a RECIST partial response (PR) and complete resolution of all brain metastases. This patient has continued on treatment for over 6 months with an ongoing PR.

CONCLUSIONS

Entrectinib demonstrated significant anti-tumor activity in a patient with NSCLC harboring an SQSTM1-NTRK1 gene rearrangement, indicating that entrectinib may be an effective therapy for tumors with NTRK gene rearrangements, including those with central nervous system metastases.

Loss of YAP1 defines neuroendocrine differentiation of lung tumors

YAP1, the main Hippo pathway effector, is a potent oncogene and is overexpressed in non‐small‐cell lung cancer (NSCLC); however, the YAP1 expression pattern in small‐cell lung cancer (SCLC) has not yet been elucidated in detail. We report that the loss of YAP1 is a special feature of high‐grade neuroendocrine lung tumors. A hierarchical cluster analysis of 15 high‐grade neuroendocrine tumor cell lines containing 14 SCLC cell lines that depended on the genes of Hippo pathway molecules and neuroendocrine markers clearly classified these lines into two groups: the YAP1‐negative and neuroendocrine marker‐positive group (n = 11), and the YAP1‐positive and neuroendocrine marker‐negative group (n = 4). Among the 41 NSCLC cell lines examined, the loss of YAP1 was only observed in one cell line showing the strong expression of neuroendocrine markers. Immunostaining for YAP1, using the sections of 189 NSCLC, 41 SCLC, and 30 large cell neuroendocrine carcinoma (LCNEC) cases, revealed that the loss of YAP1 was common in SCLC (40/41, 98%) and LCNEC (18/30, 60%), but was rare in NSCLC (6/189, 3%). Among the SCLC and LCNEC cases tested, the loss of YAP1 correlated with the expression of neuroendocrine markers, and a survival analysis revealed that YAP1‐negative cases were more chemosensitive than YAP1‐positive cases. Chemosensitivity test for cisplatin using YAP1‐positive/YAP1‐negative SCLC cell lines also showed compatible results. YAP1‐sh‐mediated knockdown induced the neuroendocrine marker RAB3a, which suggested the possible involvement of YAP1 in the regulation of neuroendocrine differentiation. Thus, we showed that the loss of YAP1 has potential as a clinical marker for predicting neuroendocrine features and chemosensitivity.

Genistein inhibits A549 human lung cancer cell proliferation via miR-27a and MET signaling

Genistein is a soybean isoflavone; in its aglycone it has various biological activities. Animal experiments, clinical studies and epidemiological investigations suggest that genistein has preventative and curative functions for a number of diseases, particularly in cancer. The present study explored the potential anti-cancer effect of genistein by observing its role in inhibiting A549 human lung cancer cell proliferation and investigating the possible mechanism. A549 cells were exposed to various concentrations of genistein (0, 10, 25, 50, 100 and 200 µM; dissolved in physiological saline) for 1, 2 and 3 days. Subsequently, the viability of A549 cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, cell apoptosis was examined using a flow cytometer, caspase 3/9 activity was measured using commercial kits, reverse transcription quantitative polymerase chain reaction was used to analyze the miR-27a expression and western blotting was used to investigate MET protein expression. The results suggested a significant inhibition of A549 cell growth following treatment with genistein in a time- and dose-dependent manner. The current study also indicated that treatment with genistein significantly induces cell apoptosis and promotes caspase-3/9 activation of A549 cells in a dose-dependent manner. Further functional assays revealed that the anti-cancer effect of genistein activated microRNA-27a (miR-27a) expression levels and reduced MET protein expression in A549 cells. In conclusion, the present study demonstrates that genistein inhibits A549 human lung cancer cell proliferation. Furthermore, this study reports, for the first time, a correlation between the anti-cancer effect of genistein and miR-27a-mediated MET signaling.

The potential of neurotrophic tyrosine kinase (NTRK) inhibitors for treating lung cancer

INTRODUCTION

Molecular alterations in neurotrophic tyrosine kinase (NTRK) genes have been identified in several solid tumors including lung cancer. Pre-clinical and clinical evidence suggested their potential role as oncogenic drivers and predictive biomarkers for targeted inhibition, leading to the clinical development of a new class of compounds blocking the NTRK molecular pathway, which are currently undner early clinical investigation.

AREA COVERED

This review describes the biology of the NTRK pathway and its molecular alterations in lung cancer. It focuses on the pre-clinical and clinical development of emerging NTRK inhibitors, which have shown very promising activity in early phase I studies.

EXPERT OPINION

Among the several NTRK-inhibitors, entrectinib and LOXO-101 are those in more advanced stage of clinical development. Both agents have shown encouraging activity along with a tolerable safety profile in patients with different solid tumors harboring NTRK-fusions, emerging as new promising therapeutic options for molecularly selected patients with advanced Trk-driven lung cancers. Results from ongoing phase II basket trials are eagerly awaited.

Genomically driven precision medicine to improve outcomes in anaplastic thyroid cancer

Thyroid cancer is an endocrine malignancy with an incidence rate that has been increasing steadily over the past 30 years. While well-differentiated subtypes have a favorable prognosis when treated with surgical resection and radioiodine, undifferentiated subtypes, such as anaplastic thyroid cancer (ATC), are far more aggressive and have a poor prognosis. Conventional therapies (surgical resection, radiation, chemotherapy, and radioiodine) have been utilized for treatment of ATC, yet these treatments have not significantly improved the overall mortality rate. As cancer is a genetic disease, genetic alterations such as mutations, fusions, activation of oncogenes, and silencing of tumor suppressors contribute to its aggressiveness. With the use of next-generation sequencing and the Cancer Genome Atlas, mutation-directed therapy is recognized as the upcoming standard of care. In this review, we highlight the known genetic landscape of ATC and the need for a comprehensive genetic characterization of this disease in order to identify additional therapeutic targets to improve patient outcomes.