Efficacy and safety of NTRK inhibitors in patients with NTRK fusion-positive lung and thyroid cancers.

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are implicated in various cancers, including those of the lung and thyroid. The prevalence of NTRK fusions is 0.1 to 0.3% in non-small cell lung cancer (NSCLC) and as high as 26% in pediatric papillary thyroid carcinoma. Detection methods include immunohistochemistry, fluorescence in situ hybridization, reverse transcription polymerase chain reaction, and next-generation sequencing. Management of NTRK fusion-positive lung cancer primarily involves targeted therapies, notably the tyrosine receptor kinase (TRK) inhibitors larotrectinib and entrectinib. Both agents demonstrate high response rates and durable disease control, particularly in metastatic adenocarcinoma of the lung. They are preferred as first-line treatments because of their efficacy over immunotherapy. Possible adverse events include dizziness, weight gain, neuropathy-like pain, and liver enzyme elevation. Larotrectinib and entrectinib also produce robust and durable responses in NTRK fusion-positive thyroid cancer that is refractory to radioactive iodine. Second-generation TRK inhibitors that have been designed to overcome acquired resistance are under investigation.

Discovery and Hit to Lead Optimization of Macrocyclic Peptides as Novel Tropomyosin Receptor Kinase A Antagonists.

Tropomyosin receptor kinases (Trks) are receptor tyrosine kinases activated by neurotrophic factors, called neurotrophins. Among them, TrkA interacts with the nerve growth factor (NGF), which leads to pain induction. mRNA-display screening was carried out to discover a hit compound 2, which inhibits protein-protein interactions between TrkA and NGF. Subsequent structure optimization improving phosphorylation inhibitory activity and serum stability was pursued using a unique process that took advantage of the peptide being synthesized by translation from mRNA. This gave peptide 19, which showed an analgesic effect in a rat incisional pain model. The peptides described here can serve as a new class of analgesics, and the structure optimization methods reported provide a strategy for discovering new peptide drugs.

Clinical characteristics and treatment patterns of patients with NTRK fusion-positive solid tumors: A multisite cohort study at US academic cancer centers.

BACKGROUND: Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are rare oncogenic drivers prevalent in 0.3% of solid tumors. They are most common in salivary gland cancer (2.6%), thyroid cancer (1.6%), and soft-tissue sarcoma (1.5%). Currently, there are 2 US Food and Drug Administration-approved targeted therapies for NTRK gene fusions: larotrectinib, approved in 2018, and entrectinib, approved in 2019. To date, the real-world uptake of tyrosine receptor kinase inhibitor (TRKi) use for NTRK-positive solid tumors in academic cancer centers remains largely unknown. OBJECTIVE: To describe the demographics, clinical and genomic characteristics, and testing and treatment patterns of patients with NTRK-positive solid tumors treated at US academic cancer centers. METHODS: This was a retrospective chart review study conducted in academic cancer centers in the United States. All patients diagnosed with an NTRK fusion-positive (NTRK1, NTRK2, NTRK3) solid tumor (any stage) and who received cancer treatment at participating sites between January 1, 2012, and July 1, 2023, were included in this study. Patient demographics, clinical characteristics, genomic characteristics, NTRK testing data, and treatment patterns were collected from electronic medical records and analyzed using descriptive statistics as appropriate. RESULTS: In total, 6 centers contributed data for 55 patients with NTRK-positive tumors. The mean age was 49.3 (SD = 20.5) years, 51% patients were female, and the majority were White (78%). The median duration of time from cancer diagnosis to NTRK testing was 85 days (IQR = 44-978). At the time of NTRK testing, 64% of patients had stage IV disease, compared with 33% at cancer diagnosis. Prevalent cancer types in the overall cohort included head and neck (15%), thyroid (15%), brain (13%), lung (13%), and colorectal (11%). NTRK1 fusions were most common (45%), followed by NTRK3 (40%) and NTRK2 (15%). Across all lines of therapy, 51% of patients (n = 28) received a TRKi. Among TRKi-treated patients, 71% had stage IV disease at TRKi initiation. The median time from positive NTRK test to initiation of TRKi was 48 days (IQR = 9-207). TRKis were commonly given as first-line (30%) or second-line (48%) therapies. Median duration of therapy was 610 (IQR = 182-764) days for TRKi use and 207.5 (IQR = 42-539) days for all other first-line therapies. CONCLUSIONS: This study reports on contemporary real-world NTRK testing patterns and use of TRKis in solid tumors, including time between NTRK testing and initiation of TRKi therapy and duration of TRKi therapy.

Neurotrophic tyrosine receptor kinase gene fusions in adult and pediatric patients with solid tumors: a clinicogenomic biobank and record linkage study of expression frequency and patient characteristics from Finland.

BACKGROUND: Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers. Using the Auria Biobank in Finland, we aimed to identify and characterize patients with these gene fusions, and describe their clinical and tumor characteristics, treatments received, and outcomes. MATERIAL AND METHODS: We evaluated pediatrics with any solid tumor type and adults with colorectal cancer (CRC), non-small cell lung cancer (NSCLC), sarcoma, or salivary gland cancer. We determined tropomyosin receptor kinase (TRK) protein expression by pan-TRK immunohistochemistry (IHC) staining of tumor samples from the Auria Biobank, scored by a certified pathologist. NTRK gene fusion was confirmed by next generation sequencing (NGS). All 2,059 patients were followed-up starting 1 year before their cancer diagnosis. RESULTS: Frequency of NTRK gene fusion tumors was 3.1% (4/127) in pediatrics, 0.7% (8/1,151) for CRC, 0.3% (1/288) for NSCLC, 0.9% (1/114) for salivary gland cancer, and 0% (0/379) for sarcoma. Among pediatrics there was one case each of fibrosarcoma (TPM3::NTRK1), Ewing's sarcoma (LPPR1::NTRK2), primitive neuroectodermal tumor (DAB2IP::NTRK2), and papillary thyroid carcinoma (RAD51B::NTRK3). Among CRC patients, six harbored tumors with NTRK1 fusions (three fused with TPM3), one harbored a NTRK3::GABRG1 fusion, and the other a NTRK2::FXN/LPPR1 fusion. Microsatellite instability was higher in CRC patients with NTRK gene fusion tumors versus wild-type tumors (50.0% vs. 4.4%). Other detected fusions were SGCZ::NTRK3 (NSCLC) and ETV6::NTRK3 (salivary gland cancer). Four patients (three CRC, one NSCLC) received chemotherapy; one patient (with CRC) received radiotherapy. CONCLUSION: NTRK gene fusions are rare in adult CRC, NSCLC, salivary tumors, sarcoma, and pediatric solid tumors.

Nerve Growth Factor Signaling Modulates the Expression of Glutaminase in Dorsal Root Ganglion Neurons during Peripheral Inflammation.

Glutamate functions as the major excitatory neurotransmitter for primary sensory neurons and has a crucial role in sensitizing peripheral nociceptor terminals producing sensitization. Glutaminase (GLS) is the synthetic enzyme that converts glutamine to glutamate. GLS-immunoreactivity (-ir) and enzyme activity are elevated in dorsal root ganglion (DRG) neuronal cell bodies during chronic peripheral inflammation, but the mechanism for this GLS elevation is yet to be fully characterized. It has been well established that, after nerve growth factor (NGF) binds to its high-affinity receptor tropomyosin receptor kinase A (TrkA), a retrograde signaling endosome is formed. This endosome contains the late endosomal marker Rab7GTPase and is retrogradely transported via axons to the cell soma located in the DRG. This complex is responsible for regulating the transcription of several critical nociceptive genes. Here, we show that this retrograde NGF signaling mediates the expression of GLS in DRG neurons during the process of peripheral inflammation. We disrupted the normal NGF/TrkA signaling in adjuvant-induced arthritic (AIA) Sprague Dawley rats by the pharmacological inhibition of TrkA or blockade of Rab7GTPase, which significantly attenuated the expression of GLS in DRG cell bodies. The results indicate that NGF/TrkA signaling is crucial for the production of glutamate and has a vital role in the development of neurogenic inflammation. In addition, our pain behavioral data suggest that Rab7GTPase can be a potential target for attenuating peripheral inflammatory pain.

[Clinicopathological and molecular characteristics of NTRK-rearranged spindle cell neoplasms in the gastrointestinal tract].

Objective: To investigate the clinicopathological, immunophenotypic and molecular genetic characteristics, and differential diagnosis of NTRK-rearranged spindle cell neoplasms (NTRK-RSCNs) in the gastrointestinal tract. Methods: Two NTRK-RSCNs diagnosed at the Department of Pathology of the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China and one case diagnosed at Zhengzhou Central Hospital, Zhengzhou, China from 2019 to 2022 were collected. The clinical data, histopathology, immunophenotypes and prognosis were analyzed. Fluorescence in situ hybridization (FISH) and next-generation sequencing (NGS) were used to detect NTRK gene rearrangements, while relevant literature was also reviewed and discussed. Results: Two patients were male and one was female, with the age of 17, 47 and 62 years, respectively. The tumors were located in the duodenum, ascending colon and descending colon, respectively. The tumors were protuberant masses with gray and rubbery sections. Their maximum diameter was 2.5, 5.0 and 10.0 cm, respectively. Histologically, the tumors invaded mucosa, intrinsic muscle and serosal adipose tissue. Tumor cells consisted of spindle or oval shaped cells with monotonous morphology and arranged in bundles or stripes pattern. Spindle cells were mildly to moderately atypical, with slightly eosinophilic cytoplasm and inconspicuous nucleoli. Necrosis and mitotic figures were observed in one high-grade tumor. All tumors expressed CD34, S-100 and pan-TRK in varying degrees. FISH analysis showed that NTRK1 gene was break-apart in 1 case and NTRK2 gene break-apart in 2 cases. NGS technologies showed LMNA::NTRK1 fusion in one case, STRN::NTRK2 fusion in another case. All patients recovered well after the surgery without recurrence at the end of the follow-up. Conclusions: NTRK-RSCN is rarely diagnosed in the gastrointestinal tract and has significant variations in morphology. It overlaps with various other mesenchymal tumors which should be considered as differential diagnoses. Be familiar with the features of histological morphology in combination with immunophenotype and molecular genetic characteristics can not only help diagnose NTRK-RSCNs, but provide therapeutic targets for clinical treatment.

Mechanistic patterns and clinical implications of oncogenic tyrosine kinase fusions in human cancers.

Tyrosine kinase (TK) fusions are frequently found in cancers, either as initiating events or as a mechanism of resistance to targeted therapy. Partner genes and exons in most TK fusions are followed typical recurrent patterns, but the underlying mechanisms and clinical implications of these patterns are poorly understood. By developing Functionally Active Chromosomal Translocation Sequencing (FACTS), we discover that typical TK fusions involving ALK, ROS1, RET and NTRK1 are selected from pools of chromosomal rearrangements by two major determinants: active transcription of the fusion partner genes and protein stability. In contrast, atypical TK fusions that are rarely seen in patients showed reduced protein stability, decreased downstream oncogenic signaling, and were less responsive to inhibition. Consistently, patients with atypical TK fusions were associated with a reduced response to TKI therapies. Our findings highlight the principles of oncogenic TK fusion formation and selection in cancers, with clinical implications for guiding targeted therapy.

Induction of resistance to neurotrophic tropomyosin-receptor kinase inhibitors by HMGCS2 via a mevalonate pathway.

INTRODUCTION: A neurotrophic tropomyosin receptor kinase (NTRK)-tyrosine kinase inhibitor (TKI) has shown dramatic efficacy against malignant tumors harboring an NTRK fusion gene. However, almost all tumors eventually acquire resistance to NTRK-TKIs. METHOD: To investigate the mechanism of resistance to NTRK-TKIs, we established cells resistant to three types of NTRK-TKIs (larotrectinib, entrectinib, and selitrectinib) using KM12 colon cancer cells with a TPM3-NTRK1 rearrangement. RESULT: Overexpression of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) was observed in three resistant cells (KM12-LR, KM12-ER, and KM12-SR) by microarray analysis. Lower expression of sterol regulatory element-binding protein 2 (SREBP2) and peroxisome proliferator activated receptor α (PPARα) was found in two cells (KM12-ER and KM12-SR) in which HMGCS2 was overexpressed compared to the parental KM12 and KM12-LR cells. In resistant cells, knockdown of HMGCS2 using small interfering RNA improved the sensitivity to NTRK-TKI. Further treatment with mevalonolactone after HMGCS2 knockdown reintroduced the NTRK-TKI resistance. In addition, simvastatin and silibinin had a synergistic effect with NTRK-TKIs in resistant cells, and delayed tolerance was observed after sustained exposure to clinical concentrations of NTRK-TKI and simvastatin in KM12 cells. In xenograft mouse models, combination treatment with entrectinib and simvastatin reduced resistant tumor growth compared with entrectinib alone. CONCLUSION: These results suggest that HMGCS2 overexpression induces resistance to NTRK-TKIs via the mevalonate pathway in colon cancer cells. Statin inhibition of the mevalonate pathway may be useful for overcoming this mechanistic resistance.

Prevalence of neurotrophic tropomyosin receptor kinase (NTRK) fusion gene positivity in patients with solid tumors in Japan.

BACKGROUND: Members of the neurotrophic tropomyosin receptor kinase (NTRK) gene family, NTRK1, NTRK2, and NTRK3 encode TRK receptor tyrosine kinases. Intra- or inter-chromosomal gene rearrangements produce NTRK gene fusions encoding fusion proteins which are oncogenic drivers in various solid tumors. METHODS: This study investigated the prevalence of NTRK fusion genes and identified fusion partners in Japanese patients with solid tumors recorded in the Center for Cancer Genomics and Advanced Therapeutics database of comprehensive genomic profiling test. RESULTS: In the analysis population (n = 46,621), NTRK fusion genes were detected in 91 patients (0.20%). The rate was higher in pediatric cases (<18 years; 1.69%) than in adults (0.16%). NTRK gene fusions were identified in 21 different solid tumor types involving 38 different partner genes including 22 (57.9%) previously unreported NTRK gene fusions. The highest frequency of NTRK gene fusions was head and neck cancer (1.31%) and thyroid cancer (1.31%), followed by soft tissue sarcoma (STS; 0.91%). A total of 97 NTRK fusion gene partners were analyzed involving mainly NTRK1 (49.5%) or NTRK3 (44.2%) gene fusions. The only fusion gene detected in head and neck cancer was ETV6::NTRK3 (n = 22); in STS, ETV6::NTRK3 (n = 7) and LMNA::NTRK1 (n = 5) were common. Statistically significant mutual exclusivity of NTRK fusions with alterations was confirmed in TP53, KRAS, and APC. NTRK gene fusion was detected from 11 STS cases: seven unclassified sarcoma, three sarcoma NOS, and one Ewing sarcoma. CONCLUSIONS: NTRK gene fusion identification in solid tumors enables accurate diagnosis and potential TRK inhibitor therapy.

Feasibility of two-step approach for screening NTRK fusion in two major subtypes of non-small cell lung cancer within a large cohort.

Our objective is to investigate a cost-effective approach to screen for NTRK fusion in the major subtypes of non-small cell lung cancer (NSCLC). Evaluate the concordance between immunohistochemistry (IHC) and next-generation sequencing (NGS), as well as between fluorescence in situ hybridization (FISH) and NGS, to detect any discrepancies in methodological consistency between lung adenocarcinoma (LADC) and lung squamous cell carcinoma (LSCC). Analyze the factors influencing IHC results. A cohort of 1654 patients with NSCLC underwent screening for NTRK fusion using whole slide IHC. The positive cases were analyzed by both FISH and NGS. Totally, 57 tested positive for pan-TRK, with positivity rates of 0.68% (10/1467) for LADC and 29.01% (47/162) for LSCC. FISH showed separate NTRK1 and NTRK3 rearrangements in two pan-TRK-positive LADCs, while all LSCCs tested negative. NGS confirmed functional NTRK fusion in two FISH-positive cases: one involving TPM3-NTRK1 and the other involving SQSTM1-NTRK3. A non-functional fusion of NTRK2-XRCC1 was detected in LSCC, while FISH was negative. According to our approach, the prevalence of NTRK fusion in NSCLC is 0.12%. The concordance rate between IHC and RNA-based NGS was 20% (2/10) in LADC and 0% (0/162) in LSCC. When the positive criteria increased over 50% of tumor cells showing strong staining, the concordance would be 100% (2/2). A concordance rate of 100% (2/2) was observed between FISH and RNA-based NGS in LADC. The expression of pan-TRK was significantly correlated with the tumor proportion score (TPS) of PD-L1 (p < 0.05) and transcript per million (TPM) values of NTRK2 (p < 0.05). We recommend using IHC with strict criteria to screen NTRK fusion in LADC rather than LSCC, confirmed by RNA-based NGS directly. When the NGS results are inconclusive, FISH validation is necessary.

A comparison of the histopathologic features of thyroid carcinomas with NTRK fusions to those with other malignant fusions.

BACKGROUND: Chromosomal rearrangements involving one of the NTRK genes result in oncogenic driver mutations in thyroid carcinoma (TC) and serve as a target for therapy. We compared the clinicopathologic features of thyroid carcinomas with NTRK fusions vs. thyroid neoplasms with other malignancy associated gene fusions within our institution. MATERIALS AND METHODS: Our pathology archives were searched from 2013 to 2023 for thyroid neoplasms with gene fusions, excluding THADA fusions and medullary thyroid carcinomas. RESULTS: 55 thyroid lesions were identified: 22 with NTRK fusions (NTRK cohort) and 33 with other fusions (non-NTRK cohort). On fine needle aspiration (FNA), 54% of the NTRK cohort were classified as Category V as per Bethesda System for Reporting Thyroid Cytology (TBSRTC) and 51.5% of non-NTRK cohort as TBSRTC Category III. In the NTRK cohort, the most common reported fusion was ETV6::NTRK3 and the most common reported fusion in the non-NTRK cohort was PAX8::PPAR-gamma. On histologic examination both cohorts were most commonly diagnosed as PTC follicular variant. Invasive features were more common in the NTRK cohort in comparison to the non-NTRK cohort. Locoregional recurrence occurred in 2/22 NTRK cases and 2/33 non-NTRK cases, with average time from surgery to recurrence being 5.5 months and 21 months, respectively. The majority of patients in both groups are alive with no evidence of disease. CONCLUSIONS: Thyroid neoplasms with a malignancy associated gene fusion are likely to be diagnosed as subtype/variant of PTC. Patients whose thyroid lesions harbor NTRK fusions present with a PTC-FV that on presentation has more aggressive clinicopathologic findings and are likely to have earlier disease recurrence.

Type II & III inhibitors of tropomyosin receptor kinase (Trk): a 2020-2022 patent update.

INTRODUCTION: The Trk family proteins are membrane-bound kinases predominantly expressed in neuronal tissues. Activated by neurotrophins, they regulate critical cellular processes through downstream signaling pathways. Dysregulation of Trk signaling can drive a range of diseases, making the design and study of Trk inhibitors a vital area of research. This review explores recent advances in the development of type II and III Trk inhibitors, with implications for various therapeutic applications. AREAS COVERED: Patents covering type II and III inhibitors targeting the Trk family are discussed as a complement of the previous review, Type I inhibitors of tropomyosin receptor kinase (Trk): a 2020-2022 patent update. Relevant patents were identified using the Web of Science database, Google, and Google Patents. EXPERT OPINION: While type II and III Trk inhibitor development has advanced more gradually compared to their type I counterparts, they hold significant promise in overcoming resistance mutations and achieving enhanced subtype selectivity - a critical factor in reducing adverse effects associated with pan-Trk inhibition. Recent interdisciplinary endeavors have marked substantial progress in the design of subtype selective Trk inhibitors, with impressive success heralded by the type III inhibitors. Notably, the emergence of mutant-selective Trk inhibitors introduces an intriguing dimension to the field, offering precise treatment possibilities.

[The relationship between differentially expressed thyroid cancer genes and clinical characteristics in metastatic children and adolescents].

Objective: To investigate the relationship between genes and clinical characteristics in children and adolescents with metastatic differentiated thyroid cancer (caDTC). Methods: A cross sectional study. A total of 67 caDTC patients with lymph node metastasis or distant metastasis in Peking Union Medical College Hospital from December 2020 to December 2022 were included, according to the inclusion and exclusion criteria. Then the differences in clinicopathologic features and iodine intake were compared among different genomes, and the age subgroups divided by the age of 12 were further analyzed. Results: Among the 67 cases of caDTC, the diagnosed age [M(Q1, Q3)]was 13.2 (9.7, 16.9) years old, with 23 males and 44 females. There were 68.7% (46/67) of patients have distant metastasis (M1 stage). Pathogenic or potentially pathogenic gene variants were detected in 68.7% (46/67) of the patients, with RET or NTRK fusion (RET/NTRK) being the most common [43.3%(29/67)], BRAF V600E mutation followed [19.4%(13/67)].There was only 1 caDTC with NRAS Q61R mutation. The patients were divided into RET/NTRK fusion group (n=29), BRAF mutation group (n=12), other mutation group (n=4), and non-mutation group (n=21) (1 patient was not included in the gene mutation subgroup comparison due to the presence of NRAS Q61R mutation and BRAF V600E mutation). The comparison of gene feature groups showed that compared to the BRAF mutation group, caDTC with RET/NTRK fusion tended to have a lower age at diagnosis [12.6(9.3, 15.9) vs 17.2(15.5, 18.1) years old, P<0.001], the proportion of mutation load≥2 was higher (10.4% vs 8.3%, P=0.027), with statistically significant difference. Among 46 M1 stage patients, 71.7% (33/46) had initial iodine intake, and 30.4% (14/46) developed radioiodine-refractory (RAIR). In age group comparison, the<12 year old group had a higher proportion of male patients (51.9% vs 22.5%, P=0.013) and a lower incidence of BRAF V600E mutations (0 vs 32.5%, P<0.001) compared to the≥12 year old group, and the differences were statistically significant. Conclusions: The incidence of RET/NTRK fusion ranks first in metastatic caDTC, featured with younger age at diagnosis and higher rate of distant metastasis. Although most metastatic lesions initially consume iodine, they are prone to RAIR. Attention should be paid to the potential role of RET/NTRK fusion in the invasion and iodine resistance of young caDTC patients.

Molecular Characterization and Inhibition of a Novel Stress-Induced Mitochondrial Protecting Role for Misfolded TrkAIII in Human SH-SY5Y Neuroblastoma Cells.

Pediatric neuroblastomas (NBs) are heterogeneous, aggressive, therapy-resistant embryonal tumors that originate from cells of neural crest origin committed to the sympathoadrenal progenitor cell lineage. Stress- and drug-resistance mechanisms drive post-therapeutic relapse and metastatic progression, the characterization and inhibition of which are major goals in improving therapeutic responses. Stress- and drug-resistance mechanisms in NBs include alternative TrkAIII splicing of the neurotrophin receptor tropomyosin-related kinase A (NTRK1/TrkA), which correlates with post-therapeutic relapse and advanced-stage metastatic disease. The TrkAIII receptor variant exerts oncogenic activity in NB models by mechanisms that include stress-induced mitochondrial importation and activation. In this study, we characterize novel targetable and non-targetable participants in this pro-survival mechanism in TrkAIII-expressing SH-SY5Y NB cells, using dithiothreitol (DTT) as an activator and a variety of inhibitors by regular and immunoprecipitation Western blotting of purified mitochondria and IncuCyte cytotoxicity assays. We report that stress-induced TrkAIII misfolding initiates this mechanism, resulting in Grp78, Ca2+-calmodulin, adenosine ribosylating factor (Arf) and Hsp90-regulated mitochondrial importation. TrkAIII imported into inner mitochondrial membranes is cleaved by Omi/high temperature requirement protein A2 (HtrA2) then activated by a mechanism dependent upon calmodulin kinase II (CaMKII), alpha serine/threonine kinase (Akt), mitochondrial Ca2+ uniporter and reactive oxygen species (ROS), involving inhibitory mitochondrial protein tyrosine phosphatase (PTPase) oxidation, resulting in phosphoinositide 3 kinase (PI3K) activation of mitochondrial Akt, which enhances stress resistance. This novel pro-survival function for misfolded TrkAIII mitigates the cytotoxicity of mitochondrial Ca2+ homeostasis disrupted during integrated stress responses, and is prevented by clinically approved Trk and Akt inhibitors and also by inhibitors of 78kDa glucose regulated protein (Grp78), heat shock protein 90 (Hsp90), Ca2+-calmodulin and PI3K. This identifies Grp78, Ca2+-calmodulin, Hsp90, PI3K and Akt as novel targetable participants in this mechanism, in addition to TrkAIII, the inhibition of which has the potential to enhance the stress-induced elimination of TrkAIII-expressing NB cells, with the potential to improve therapeutic outcomes in NBs that exhibit TrkAIII expression and activation.

Effects of oral administration of nonselective Trk inhibitor on bladder overactivity in rodent models of prostatic inflammation.

BACKGROUND: Our research focused on the assessment of the impact of systemic inhibition of Trk receptors, which bind to nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), on bladder hypersensitivity in two distinct rodent models of prostatic inflammation (PI). METHODS: Male Sprague-Dawley rats were divided into three groups (n = 6 each): the control group (no PI, vehicle administration), the untreated group (PI, vehicle administration), and the treated group (PI, nonselective Trk inhibitor, GNF 5837, administration). PI in rats was induced by a intraprostatic injection of 5% formalin. Posttreatment, we carried out conscious cystometry and a range of histological and molecular analyses. Moreover, the study additionally evaluated the effects of a nonselective Trk inhibitor on bladder overactivity in a mouse model of PI, which was induced by prostate epithelium-specific conditional deletion of E-cadherin. RESULTS: The rat model of PI showed upregulations of NGF and BDNF in both bladder and prostate tissues in association with bladder overactivity and inflammation in the ventral lobes of the prostate. GNF 5837 treatment effectively mitigated these PI-induced changes, along with reductions in TrkA, TrkB, TrkC, and TRPV1 mRNA expressions in L6-S1 dorsal root ganglia. Also, in the mouse PI model, GNF 5837 treatment similarly improved bladder overactivity. CONCLUSIONS: The findings of our study suggest that Trk receptor inhibition, which reduced bladder hypersensitivity and inflammatory responses in the prostate, along with a decrease in overexpression of Trk and TRPV1 receptors in sensory pathways, could be an effective treatment strategy for male lower urinary tract symptoms associated with PI and bladder overactivity.