Neurotrophic Tyrosine Receptor Kinase Gene Research Articles

Real-Life Experience with Entrectinib in Neurotrophic Tyrosine Receptor Kinase Fusion-Positive Solid Tumors: A Multicenter Retrospective Trial.

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions represent rare somatic mutations in many types of cancer and have enabled the use of promising targeted therapies. In clinical studies, increased response rates to tropomyosin receptor kinase inhibitors have been demonstrated in NTRK fusion-positive cancer types; however, real-world experiences on these targeted agents are scarce. We evaluated the clinical characteristics and treatment responses of NTRK fusion-positive patients who received entrectinib treatment within the scope of an early access program in Turkey. This multicenter, retrospective analysis involved 17 patients with solid tumors harboring NTRK fusions or rearrangements from 14 oncology centers between June 2019 and 31 March 2024. Demographic and clinical data were obtained via retrospective review of medical records with a cutoff date of 31 March 2024. The median age at diagnosis of the patients in our study was 42 [interquartile range (IQR) 33-60] years. Nine different types of solid tumors were diagnosed in these patients. The most common NTRK gene rearrangements involved NTRK1 (n=8), followed by NTRK3 (n=7). The median duration of entrectinib usage was 6.9 (IQR 3.1-16.1) months. Dose reductions due to side effects were performed in four patients: two due to leukopenia, one due to visual disturbance, and one due to troponin elevation. Leukopenia was the most commonly observed side effect. The objective response rate (ORR) was 35.3% (95% confidence interval (CI) 14.2-62.7), with complete response (CR) achieved in four patients. The duration of response (DOR) in patients who responded after initiating entrectinib was 9.8 (95% CI 0-30.7) months, the median overall survival (mOS) in all patients was 20.8 (95% CI 0-48.5) months, and the time-to-treatment failure (TTF) was 6.4 (95% CI 0-13.5) months. In this retrospective study, we aimed to obtain real-world data concerning the use of entrectinib in patients with solid tumors harboring NTRK fusion genes. Although our findings are partially similar to the results of clinical studies, prospective studies in larger patient groups with more diverse tumor types and different demographic characteristics are needed to confirm the findings.

Cytologic testing for mismatch repair deficiency/microsatellite instability and NTRK gene fusion is not routinely indicated in primary pancreaticobiliary carcinoma cell block material

Pancreaticobiliary carcinomas rarely harbor targetable genetic alterations, including microsatellite instability (MSI) or neurotrophic tyrosine receptor kinase (NTRK) gene fusions. As these malignancies are typically present at an advanced stage and have suboptimal response to chemotherapy, the discovery of an actionable genomic alteration provides an additional avenue of treatment for chemotherapy-refractory cases. In this study, we evaluate 319 cases of pancreaticobiliary carcinoma diagnosed on fine-needle aspiration biopsy or biliary brushing for DNA mismatch repair (MMR) protein deficiency and pan-TRK overexpression by immunohistochemistry (IHC) and compare these results to MSI and NTRK gene fusion molecular testing. Although we find a high concordance between MMR protein IHC and MSI molecular testing in the evaluation of MMR deficiency and between pan-TRK IHC and NTRK fusion testing by next-generation sequencing, the low prevalence of either of these genetic alterations in our cohort casts doubt on the value of screening cases of pancreaticobiliary carcinoma for MMR protein deficiency and NTRK fusions.

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.

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. 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. 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. NTRK gene fusions are rare in adult CRC, NSCLC, salivary tumors, sarcoma, and pediatric solid tumors.

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

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. 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. 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. 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. 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.

Detection and Significance of Molecular Markers in Immunotherapy and Targeted Therapy of Colorectal Cancer in Tibet

Objective To study the expression of SWI/SNF-related,matrix-associated,actin-dependent regulator of chromatin,subfamily A,member 4(SMARCA4)/Brahma-related gene 1,V-raf murine sarcoma viral oncogene homolog B(BRAF),P53,programmed cell death protein-1(PD-1),and programmed death-ligand 1(PD-L1),and changes in the expression of BRAF and neurotrophic tyrosine receptor kinase(NTRK) in the patients with colorectal cancer in Tibet,thereby providing a basis for targeted therapy and immunotherapy for this disease in Tibet. Methods A total of 64 patients with colorectal cancer resected in the Tibet Autonomous Region People's Hospital from January 2015 to July 2021 were enrolled in this study.The expression of SMARCA4,BRAF,P53,PD-1,and PD-L1 was detected by immunohistochemical staining.The gene fusion involving NTRK1,NTRK2,and NTRK3 was detected by fluorescence in situ hybridization,and the BRAF V600E gene mutation by polymerase chain reaction. Results The 64 patients with colorectal cancer were at a male-to-female ratio of 1.21∶1,with the mean age of (56.59±13.27) years.The tumors were located in the colon in 46(71.88%) patients and in the rectum in 18(28.12%) patients.Sixty(93.75%) patients presented adenocarcinoma,and 4(6.25%) patients presented other types of tumors.The patients in T1/T2 and T3/T4 phases accounted for 17.19%(n=11) and 82.81%(n=53),respectively.Lymph node metastasis occurred in 24(37.50%) patients.The immunohistochemical staining results showed partially down-regulated or absent expression of SMARCA4 in 1(1.56%) patient,positive BRAF expression in 4(6.25%) patients,and mutant expression of P53 in 35(54.69%) patients.The PD-1-expressing tumor associated immune cell was proportion score<10% in 45(70.31%) patients and≥10% in 19(29.69%) patients.The PD-L1 combined positive score was<10 in 52(81.25%) patients and≥10 in 12(18.75%) patients.The gene fusion of NTRK1,NTRK2,and NTRK3 was negative in all the patients,and BRAF V600E gene mutation was positive in 4(6.25%) patients.The SMARCA4 gene alteration was not detected in the patient with partial expression missing of SMARCA4.The PD-L1 combine positive score was correlated with the deficient mismatch repair(dMMR)/microsatellite instability-high (MSI-H) and the PD-1 expression (χ2=10.223,P=0.001;χ2=11.979,P=0.001). Conclusions The down-regulated or absent SMARCA4 expression and NTRK gene fusion are rare in the patients with colorectal cancer in Tibet.A few patients present BRAF V600E gene mutations,and Pan-TRK and BRAF expression can be used for the primary screening of NTRK gene fusion and BRAF gene mutation.The patients with dMMR/MSI-H are prone to high expression of PD-L1 and expected to benefit from immunotherapy.No significant correlation exists between P53 mutation and PD-L1 expression.The high expression of PD-1 is positively correlated with the high expression of PD-L1.

NTRK Therapy among Different Types of Cancers, Review and Future Perspectives.

Neurotrophic tyrosine receptor kinase (NTRK) has been a remarkable therapeutic target for treating different malignancies, playing an essential role in oncogenic signaling pathways. Groundbreaking trials like NAVIGATE led to the approval of NTRK inhibitors by the Food and Drug Administration (FDA) to treat different malignancies, significantly impacting current oncology treatment. Accurate detection of NTRK gene fusion becomes very important for possible targeted therapy. Various methods to detect NTRK gene fusion have been applied widely based on sensitivity, specificity, and accessibility. The utility of different tests in clinical practice is discussed in this study by providing insights into their effectiveness in targeting patients who may benefit from therapy. Widespread use of NTRK inhibitors in different malignancies could remain limited due to resistance mechanisms that cause challenges to medication efficacy in addition to common side effects of the medications. This review provides a succinct overview of the application of NTRK inhibitors in various types of cancer by emphasizing the critical clinical significance of NTRK fusion gene detection. The discussion also provides a solid foundation for understanding the current challenges and potential changes for improving the efficacy of NTRK inhibitor therapy to treat different malignancies.

Neurotrophic-tyrosine receptor kinase gene fusion in papillary thyroid cancer: A clinicogenomic biobank and record linkage study from Finland.

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.

From genomic spectrum of NTRK genes to adverse effects of its inhibitors, a comprehensive genome-based and real-world pharmacovigilance analysis.

Introduction: The discovery of neurotrophic tyrosine receptor kinase (NTRK) gene fusions has facilitated the development of precision oncology. Two first-generation NTRK inhibitors (larotrectinib and entrectinib) are currently approved for the treatment of patients with solid tumors harboring NTRK gene fusions. Nevertheless, comprehensive NTRK profiling at the pan-cancer genomic level and real-world studies pertaining to the adverse events of NTRK inhibitors are lacking. Methods: We characterize the genome of NTRK at the pan-cancer level through multi-omics databases such as The Cancer Genome Atlas (TCGA). Through the FDA Adverse Event Reporting System (FAERS) database, we collect reports of entrectinib and larotrectinib-induced adverse events and perform a pharmacovigilance analysis using various disproportionality methods. Results: NTRK1/2/3 expression is lower in most tumor tissues, while they have higher methylation levels. NTRK gene expression has prognostic value in some cancer types, such as breast invasive carcinoma (BRCA). The cancer type with highest NTRK alteration frequency is skin cutaneous melanoma (SKCM) (31.98%). Thyroid carcinoma (THCA) has the largest number of NTRK fusion cases, and the most common fusion pair is ETV6-NTRK3. Adverse drug events (ADEs) obtained from the FAERS database for larotrectinib and entrectinib are 524 and 563, respectively. At the System Organ Class (SOC) level, both drugs have positive signal value for "nervous system disorder". Other positive signals for entrectinib include "cardiac disorders", "metabolism and nutrition disorders", while for larotrectinib, it is "hepatobiliary disorders". The unexpected signals are also listed in detail. ADEs of the two NTRK inhibitors mainly occur in the first month. The median onset time of ADEs for entrectinib and larotrectinib was 16 days (interquartile range [IQR] 6-86.5) and 44 days ([IQR] 7-136), respectively. Conclusion: Our analysis provides a broad molecular view of the NTRK family. The real-world adverse drug event analysis of entrectinib and larotrectinib contributes to more refined medication management.

NTRK2 expression in gastrointestinal stromal tumors with a special emphasis on the clinicopathological and prognostic impacts

Gastrointestinal stromal tumors (GISTs) are typically characterized by activating mutations of the KIT proto-oncogene receptor tyrosine kinase (KIT) or platelet-derived growth factor receptor alpha (PDGFRA). Recently, the neurotrophic tyrosine receptor kinase (NTRK) fusion was reported in a small subset of wild-type GIST. We examined trk IHC and NTRK gene expressions in GIST. Pan-trk immunohistochemistry (IHC) was positive in 25 (all 16 duodenal and 9 out of 16 small intestinal GISTs) of 139 cases, and all pan-trk positive cases showed diffuse and strong expression of c-kit. Interestingly, all of these cases showed only trkB but not trkA/trkC expression. Cap analysis of gene expression (CAGE) analysis identified increased number of genes whose promoters were activated in pan-trk/trkB positive GISTs. Imbalanced expression of NTRK2, which suggests the presence of NTRK2 fusion, was not observed in any of trkB positive GISTs, despite higher mRNA expression. TrkB expression was found in duodenal GISTs and more than half of small intestinal GISTs, and this subset of cases showed poor prognosis. However, there was not clear difference in clinical outcomes according to the trkB expression status in small intestinal GISTs. These findings may provide a possible hypothesis for trkB overexpression contributing to the tumorigenesis and aggressive clinical outcome in GISTs of duodenal origin.

Detection of Novel Tyrosine Kinase Fusion Genes as Potential Therapeutic Targets in Bone and Soft Tissue Sarcomas Using DNA/RNA-based Clinical Sequencing.

Approximately 1% of clinically treatable tyrosine kinase fusions, including anaplastic lymphoma kinase, neurotrophic tyrosine receptor kinase, RET proto-oncogene, and ROS proto-oncogene 1, have been identified in soft tissue sarcomas via comprehensive genome profiling based on DNA sequencing. Histologic tumor-specific fusion genes have been reported in approximately 20% of soft tissue sarcomas; however, unlike tyrosine kinase fusion genes, these fusions cannot be directly targeted in therapy. Approximately 80% of tumor-specific fusion-negative sarcomas, including myxofibrosarcoma and leiomyosarcoma, that are defined in complex karyotype sarcomas remain genetically uncharacterized; this mutually exclusive pattern of mutations suggests that other mutually exclusive driver oncogenes are yet to be discovered. Tumor-specific, fusion-negative sarcomas may be associated with unique translocations, and oncogenic fusion genes, including tyrosine kinase fusions, may have been overlooked in these sarcomas. (1) Can DNA- or RNA-based analysis reveal any characteristic gene alterations in bone and soft tissue sarcomas? (2) Can useful and potential tyrosine kinase fusions in tumors from tumor-specific, fusion-negative sarcomas be detected using an RNA-based screening system? (3) Do the identified potential fusion tumors, especially in neurotrophic tyrosine receptor kinase gene fusions in bone sarcoma, transform cells and respond to targeted drug treatment in in vitro assays? (4) Can the identified tyrosine kinase fusion genes in sarcomas be useful therapeutic targets? Between 2017 and 2020, we treated 100 patients for bone and soft tissue sarcomas at five institutions. Any biopsy or surgery from which a specimen could be obtained was included as potentially eligible. Ninety percent (90 patients) of patients were eligible; a further 8% (8 patients) were excluded because they were either lost to follow-up or their diagnosis was changed, leaving 82% (82 patients) for analysis here. To answer our first and second questions regarding gene alterations and potential tyrosine kinase fusions in eight bone and 74 soft tissue sarcomas, we used the TruSight Tumor 170 assay to detect mutations, copy number variations, and gene fusions in the samples. To answer our third question, we performed functional analyses involving in vitro assays to determine whether the identified tyrosine kinase fusions were associated with oncogenic abilities and drug responses. Finally, to determine usefulness as therapeutic targets, two pediatric patients harboring an NTRK fusion and an ALK fusion were treated with tyrosine kinase inhibitors in clinical trials. DNA/RNA-based analysis demonstrated characteristic alterations in bone and soft tissue sarcomas; DNA-based analyses detected TP53 and copy number alterations of MDM2 and CDK4 . These single-nucleotide variants and copy number variations were enriched in specific fusion-negative sarcomas. RNA-based screening detected fusion genes in 24% (20 of 82) of patients. Useful potential fusions were detected in 19% (11 of 58) of tumor-specific fusion-negative sarcomas, with nine of these patients harboring tyrosine kinase fusion genes; five of these patients had in-frame tyrosine kinase fusion genes ( STRN3-NTRK3, VWC2-EGFR, ICK-KDR, FOXP2-MET , and CEP290-MET ) with unknown pathologic significance. The functional analysis revealed that STRN3-NTRK3 rearrangement that was identified in bone had a strong transforming potential in 3T3 cells, and that STRN3-NTRK3 -positive cells were sensitive to larotrectinib in vitro. To confirm the usefulness of identified tyrosine kinase fusion genes as therapeutic targets, patients with well-characterized LMNA-NTRK1 and CLTC-ALK fusions were treated with tyrosine kinase inhibitors in clinical trials, and a complete response was achieved. We identified useful potential therapeutic targets for tyrosine kinase fusions in bone and soft tissue sarcomas using RNA-based analysis. We successfully identified STRN3-NTRK3 fusion in a patient with leiomyosarcoma of bone and determined the malignant potential of this fusion gene via functional analyses and drug effects. In light of these discoveries, comprehensive genome profiling should be considered even if the sarcoma is a bone sarcoma. There seem to be some limitations regarding current DNA-based comprehensive genome profiling tests, and it is important to use RNA testing for proper diagnosis and accurate identification of fusion genes. Studies on more patients, validation of results, and further functional analysis of unknown tyrosine kinase fusion genes are required to establish future treatments. DNA- and RNA-based screening systems may be useful for detecting tyrosine kinase fusion genes in specific fusion-negative sarcomas and identifying key therapeutic targets, leading to possible breakthroughs in the treatment of bone and soft tissue sarcomas. Given that current DNA sequencing misses fusion genes, RNA-based screening systems should be widely considered as a worldwide test for sarcoma. If standard treatments such as chemotherapy are not effective, or even if the sarcoma is of bone, RNA sequencing should be considered to identify as many therapeutic targets as possible.

CTNI-74. ON-TRK: A NON-INTERVENTIONAL STUDY OF LAROTRECTINIB IN PATIENTS WITH TROPOMYOSIN RECEPTOR KINASE (TRK) FUSION SOLID TUMORS

Abstract Increasingly, health authorities and the medical community are investing resources into evaluating real-world data (RWD) on precision biomarker-based treatments. Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers in various cancers. Larotrectinib is a highly selective, central nervous system (CNS)-active TRK inhibitor approved for tumor-agnostic use in pediatric and adult patients with various cancers. ON-TRK (NCT04142437) is an ongoing non-interventional post-approval study that is critical in gaining RWD on the treatment of patients with TRK fusion cancer and will contribute to the broader understanding of personalized therapy. This open-label, global, multi-cohort, prospective study will enroll up to 300 pediatric and adult patients with TRK fusion cancer scheduled to receive larotrectinib, including ≥ 30 pediatric patients. Patients with cancer harboring NTRK gene fusions, detected locally, are eligible. Patients who have had prior TRK inhibitor therapy and patients with NTRK genomic alterations other than functional gene fusions are excluded. Decisions on the dose and duration of treatment are at the discretion of the treating physician. The primary endpoint is safety, including specific long-term parameters in pediatric patients. Secondary endpoints include: efficacy (objective response rate, disease control rate, time to response, duration of response, progression-free survival, and overall survival), dosing patterns and long-term effects of larotrectinib in pediatric patients. The effects of larotrectinib on growth and developmental milestones in pediatric patients will be reported, including change in height and weight from baseline, age at adrenarche for males and menarche for females, number and percentage of patients with abnormal Tanner stages, and abnormal neurological assessments. All variables will be analyzed using descriptive statistics. Pediatric and adult patients will be followed for ≥ 5 years and ≥ 2 years, respectively, unless lost to follow-up, withdrawal, or death. Enrollment is ongoing worldwide; 24 patients with primary CNS cancer have been enrolled to date.

Phase separation underlies signaling activation of oncogenic NTRK fusions

NTRK (neurotrophic tyrosine receptor kinase) gene fusions that encode chimeric proteins exhibiting constitutive activity of tropomyosin receptor kinases (TRK), are oncogenic drivers in multiple cancer types. However, the underlying mechanisms in oncogenesis that involve various N-terminal fusion partners of NTRK fusions remain elusive. Here, we show that NTRK fusion proteins form liquid-like condensates driven by their N-terminal fusion partners. The kinase reactions are accelerated in these condensates where the complexes for downstream signaling activation are also concentrated. Our work demonstrates that the phase separation driven by NTRK fusions is not only critical for TRK activation, but the condensates formed through phase separation serve as organizational hubs for oncogenic signaling.

Larotrectinib long-term efficacy and safety in adult patients (pts) with tropomyosin receptor kinase (TRK) fusion cancer.

3141 Background: Neurotrophic tyrosine receptor kinase ( NTRK) gene fusions are oncogenic drivers in a broad array of tumor types. Larotrectinib is a first-in-class, highly selective, central nervous system (CNS)-active TRK inhibitor approved for tumor-agnostic use in pts with TRK fusion cancer based on a rapid, robust, and durable objective response rate (ORR) in both adult and pediatric pts with various non-primary CNS cancers. Here, we report data on an expanded cohort of adult pts with TRK fusion cancer treated with larotrectinib. Methods: Adults with non-primary CNS TRK fusion cancer treated in three larotrectinib clinical trials (NCT02576431, NCT02122913, and NCT02637687) were included. Larotrectinib was administered at 100 mg twice daily in most pts. Responses were assessed per Independent Review Committee (IRC) using RECIST v1.1. Data cut-off: July 2022. Results: As of July 2022, there were 194 adult pts enrolled, with 180 eligible for efficacy analyses by IRC; 22 pts had known brain metastases at baseline. There were 24 different tumor types; the most common were lung (n=30; 15%), soft tissue sarcoma (n=30; 15%), thyroid (n=28; 14%), salivary gland (n=25; 13%), and colon (n=23; 12%). Median age was 57 years (range 19–90). The gene fusions involved NTRK1 (n=90; 46%), NTRK2 (n=7; 4%), or NTRK3 (n=97; 50%). Pts had previously received a median of one systemic therapy (range 0–10). ORR was 57% (95% CI 50–65): 29 (16%) complete response (including one pathological complete response), 74 (41%) partial response, 39 (22%) stable disease, 23 (13%) progressive disease, and 15 (8%) not evaluable. ORR in 22 evaluable pts with baseline CNS metastases was 68% (95% CI 45–86). Median time to response was 1.8 months, and median duration of response was 43.3 months (95% CI 29.2–not estimable [NE]) at a median follow-up of 32.3 months. Median progression-free survival was 24.6 months (95% CI 11.3–34.5) at a median follow-up of 28.5 months. Median overall survival was 48.7 months (95% CI 38.5–NE) at a median follow-up of 33.8 months. At data cut-off, 39 of the 73 pts who had disease progression continued treatment post-progression for ≥4 weeks. Treatment-related adverse events (TRAEs) were predominantly Grade 1/2. Grade 3/4 TRAEs occurred in 27 (14%) pts. Treatment discontinuation due to TRAEs was reported in one pt (increased alanine aminotransferase and aspartate aminotransferase). Conclusions: In this expanded dataset with extended follow-up, larotrectinib continues to demonstrate rapid and durable responses, extended survival, and a favorable safety profile in adults with TRK fusion cancer, including those with CNS metastases. These results support the wider adoption of next-generation sequencing panels that include NTRK gene fusions when testing pts with solid tumors; this ensures that pts are offered the right medicine for their disease as soon as possible. Clinical trial information: NCT02576431 , NCT02122913 , NCT02637687 .

Larotrectinib (laro) long-term efficacy and safety in patients (pts) with tropomyosin receptor kinase (TRK) fusion thyroid carcinoma (TC).

6091 Background: Neurotrophic tyrosine receptor kinase ( NTRK) gene fusions are oncogenic drivers in a variety of tumor types, including TC. Laro is a first-in-class, highly selective, central nervous system (CNS)-active TRK inhibitor approved for tumor-agnostic use in pts with TRK fusion cancer based on a rapid, robust, and durable objective response rate (ORR) in both adult and pediatric pts with various cancers. Here, we report data on the subset of pts with TRK fusion TC treated with larotrectinib with long-term follow-up. Methods: Pts with TRK fusion TC enrolled in three laro clinical trials (NCT02576431, NCT02122913, NCT02637687) were included. Laro was administered at 100 mg twice daily to most pts; two pediatric pts received 100 mg/m2. Responses were assessed per independent review committee (IRC) using RECIST v1.1. Data cut-off: July 20, 2022. Results: As of data cut-off, 30 pts were eligible for efficacy assessment by IRC. The median age was 61.5 years (range 6–80) and the median time since initial cancer diagnosis was 5.0 years (range 0–46). The gene fusions involved NTRK1 (n =14; 47%) or NTRK3 (n =16; 53%). Fifteen pts (50%) received no prior systemic therapies, and six (20%) received ≥2; 23 (77%) received prior radioiodine. ORR was 63% (95% confidence interval [CI] 44–80): three (10%) complete response, 16 (53%) partial response (PR), five (17%) stable disease, four (13%) progressive disease, and two (7%) not evaluable. For pts classified as differentiated TC (DTC; n = 23), the ORR was 78% (95% CI 56–93). For pts classified as anaplastic TC (ATC; n = 7), the ORR was 14% (95% CI 0–58). All four pts with CNS metastases at baseline had a PR. Median time to response was 1.9 months, and median duration of response (DoR) was 43.3 months (95% CI 21.6–not estimable [NE]) at a median follow-up of 32.3 months. Median progression-free survival was 35.5 months (95% CI 23.4–NE) at a median follow-up of 34.0 months. Median overall survival (OS) was not reached (NR; 95% CI 48.7–NE) at a median follow-up of 46.4 months; the 48-month OS rate was 71% (95% CI 54–88). Median OS was NR (95% CI 48.7–NE) in DTC and 8.8 months (95% CI 2.6–NE) in ATC. At data cut-off, five pts who had disease progression continued treatment for ≥4 weeks due to continued clinical benefit. Treatment-related adverse events (TRAEs) were predominantly Grade 1–2. Grade ≥3 TRAEs were reported in two (7%) pts (anemia and decreased lymphocyte count). There were no treatment discontinuations due to TRAEs. Conclusions: Laro continues to demonstrate a rapid and durable response, extended survival, and a favorable safety profile in pts with TRK fusion DTC. Limited single-agent activity was observed in ATC. These results support the wider adoption of next generation sequencing panels, which include NTRK gene fusions, in pts with advanced TC prior to the initiation of any systemic therapy. Clinical trial information: NCT02576431 , NCT02122913 , NCT02637687 .

NTRK gene aberrations in triple-negative breast cancer: detection challenges using IHC, FISH, RT-PCR, and NGS.

Triple-negative breast cancer (TNBC) is usually an aggressive disease with a poor prognosis and limited treatment options. The neurotrophic tyrosine receptor kinase (NTRK) gene fusions are cancer type-agnostic emerging biomarkers approved by the Food and Drug Administration (FDA), USA, for the selection of patients for targeted therapy. The main aim of our study was to investigate the frequency of NTRK aberrations, i.e. fusions, gene copy number gain, and amplification, in a series of TNBC using different methods. A total of 83 TNBCs were analyzed using pan-TRK immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), real-time polymerase chain reaction (RT-PCR), and RNA-based next-generation sequencing (NGS). Of 83 cases, 16 showed pan-TRK positivity although no cases had NTRK-fusions. Indeed, FISH showed four cases carrying an atypical NTRK1 pattern consisting of one fusion signal and one/more single green signals, but all cases were negative for fusion by NGS and RT-PCR testing. In addition, FISH analysis showed six cases with NTRK1 amplification, one case with NTRK2 copy number gain, and five cases with NTRK3 copy number gain, all negative for pan-TRK IHC. Our data demonstrate that IHC has a high false-positive rate for the detection of fusions and molecular testing is mandatory; there is no need to perform additional molecular tests in cases negativity for NTRK by IHC. In conclusion, the NTRK genes are not involved in fusions in TNBC, but both copy number gain and amplification are frequent events, suggesting a possible predictive role for other NTRK aberrations.

Abstract CT228: Concordance between tissue and circulating tumor DNA (ctDNA) testing for neurotrophic tyrosine receptor kinase (NTRK) gene fusions in larotrectinib (laro) clinical trials

Abstract Background: NTRK gene fusions are oncogenic drivers in various tumor types. Laro, a highly selective and central nervous system (CNS)-active tropomyosin receptor kinase (TRK) inhibitor, is approved for the treatment of patients (pts) with TRK fusion cancer. Laro demonstrated an objective response rate (ORR) of 69% in 244 pts with solid (non-primary CNS) tumors (Drilon et al. ASCO 2022). Here, we report on the concordance between baseline local tissue-based testing with central tissue-based and liquid biopsy-based ctDNA testing to identify NTRK gene fusions. Methods: Pts with non-primary CNS TRK fusion cancer who underwent independent review committee assessments by July 15, 2019, in three laro clinical trials (NCT02122913, NCT02576431, and NCT02637687) were included. Tumor NTRK gene fusion status was determined locally by a variety of methods, and centrally by next-generation sequencing in both tissue (using Illumina TruSight™ Oncology Comprehensive) and ctDNA (using Guardant360® or GuardantOMNI®) at baseline. Data cut-off: July 20, 2021. Results: Of the 164 pts with NTRK fusions identified by local testing, 117 had evaluable tissue samples for central testing, and 99 had evaluable liquid biopsy samples. In total, 81.2% (95/117) of tumors had the fusion confirmed by central tissue testing. ctDNA testing detected NTRK gene fusions in 33.3% (33/99) of patients. Positive predictive values for each NTRK gene fusion are shown in the Table. The ORR for pts with NTRK gene fusions determined by local and central testing will be presented. Conclusions: A high proportion of tumors with locally identified NTRK gene fusions were confirmed centrally. At present, analysis of ctDNA is significantly less sensitive at detecting NTRK gene fusions. A negative ctDNA result requires next-generation sequencing testing of a tissue biopsy. Further research is needed to improve the sensitivity of ctDNA gene fusion detection. Table NTRK gene fusion Tissue-based LT Tissue-based CT ctDNA-based CT with LB Fusion confirmed, n Fusion confirmed, n Fusion not detected, n Unavailable samples, n† PPV‡: CT vs tissue-based LT, % Fusion confirmed, n Fusion not detected, n Unavailable samples, n† PPV‡: LB vs tissue-based LT, % NTRK1 68 35 14 19 71.4 20 34 14 37.0 NTRK2 4 3 1 0 75.0 0 4 0 0 NTRK3 92§ 57 7 28 89.1 13 28 51 31.7 †Includes no sample available and sample QC failed. ‡Calculated as a percentage of the number of confirmed fusions over the number of available samples. §Includes 9 inferred NTRK3 fusions. CT, central testing; ctDNA, circulating tumor DNA; LB, liquid biopsy; LT, local testing; NTRK, neurotrophic tyrosine receptor kinase; PPV, positive predictive value; QC, quality control. Citation Format: Erin R. Rudzinski, Marc Ladanyi, Lauren L. Ritterhouse, Felix Sahm, Ricarda Norenberg, Hong Zheng, Chi Chen, Vadim Bernard-Gauthier, Nicoletta Brega, Cornelis M. van Tilburg, Jessica J. Lin, Marcia S. Brose, Ulrik N. Lassen, Ray McDermott, Theodore W. Laetsch, David S. Hong, Alexander Drilon, Sinchita Roy-Chowdhuri. Concordance between tissue and circulating tumor DNA (ctDNA) testing for neurotrophic tyrosine receptor kinase (NTRK) gene fusions in larotrectinib (laro) clinical trials [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT228.

Exploring the binding characteristics of bovine serum albumin with tyrosine kinase inhibitor entrectinib: Multi-spectral analysis and theoretical calculation

Entrectinib (ENB) is one of multi-target tyrosine kinase inhibitors, which is mainly used for treating neurotrophic tyrosine receptor kinase gene fusion positive solid tumors. The binding characteristics of ENB and bovine serum albumin (BSA) were studied by experiments and theoretical calculations. The steady-state fluorescence showed that ENB quenched the fluorescence of BSA through mixed quenching, and ENB was dominated by static quenching at low concentration. ENB and BSA had a moderate affinity, formed a complex with a stoichiometric ratio of 1:1 and the binding constant of about 105 M−1 at 298 K, and Förster non-radiative energy transfer occurs. According to the driving force competition experiment, thermodynamic parameter analysis and theoretical calculation, hydrogen bond, van der Waals force and hydrophobic force were the main factors affecting the stability of the ENB-BSA complex. Molecular docking and site markers competition showed that ENB spontaneously bound to the Site III of BSA so that ENB could make the skeleton of BSA loose, the spatial structure of BSA changed (α-helix decreased by 3.1%, random coil increased by 1.7%), and the microenvironment of Tyr and Trp residues changed. The existence of Co2+ metal ions can enhance the binding effect, thus prolonging the half-life of ENB in vivo, which may improve the efficacy of ENB, while Ca2+, Cu2+ and Mg2+ metal ions will reduce the efficacy of ENB.

The role of claudin 18.2 and HER-2 in pancreatic cancer outcomes.

To examine the prognostic value of claudin 18.2 (CLDN18.2) and human epidermal growth factor receptor-2 (HER-2) expression in patients with resected pancreatic ductal adenocarcinoma (PDAC). This study enrolled patients who underwent surgery and were diagnosed with PDAC at Suleyman Demirel University Hospital, Turkey between 2015 and 2019. Sixty-eight patients with resected PDAC treated at a medical oncology clinic were assessed. All patients were over the age of 18 years, underwent follow-up and treatment in our unit, and had pathology slides that we could access. Clinicopathological data were obtained from medical files, including the patients' age, sex, pathological parameters, and clinical stage according to the Eighth International Union against Cancer/American Joint Committee on Cancer. Patient survival and the period from the date of diagnosis to death were assessed in the follow-up data. There was no statistically significant difference between CLDN18.2 and HER-2 expression scores for samples and patient clinicopathological characteristics. No HER-2 expression scores of ≥2 were found in the samples. Only 25% (n = 17) of the samples had HER-2 expression scores of +1. CLDN18.2 expression was detected in 54.4% (n = 37) of the patient samples. CLDN18.2 expression scores were +1 in 30.8% (n = 21) of the patient samples, +2 in 16.2% (n = 11), and +3 in 7.4% (n = 5). When CLDN18.2 and HER-2 expression were compared, a statistically significant difference and moderate positive correlation were observed. No significant relationship between HER-2 expression and survival was observed in the survival analysis of PDAC patients; however, high CLDN18.2 expression was related to longer overall survival. Our study is the third to research CLDN18.2 expression in PDAC. HER-2 expression is low and CLDN18.2 expression is high in patients with PDAC. HER-2 expression is not related to overall survival but CLDN18.2 is related and may be used as a prognostic marker in patients with PDAC.

Design of novel anti-cancer drugs targeting TRKs inhibitors based 3D QSAR, molecular docking and molecular dynamics simulation

Tropomyosin receptor kinase (TRK) enzymes are responsible for different types of tumors caused by neurotrophic tyrosine receptor kinase gene fusion and have been identified as an effective target for anticancer therapy. The study of the mechanism between polo-like kinase (PLKs) and pyrazol inhibitors was performed using 3D-QSAR modeling, molecular docking, and MD simulations in order to design high-activity inhibitors. The HQSAR (Q 2 = 0.793, R 2 = 0.917, R 2 ext = 0.961), CoMFA (Q 2 = 0.582, R 2 = 0.722, R 2 ext = 0.951), CoMSIA/SE (Q 2 = 0.603, R 2 = 0.801, R 2 ext = 0.849), and Topomer CoMFA (Q 2 = 0.726, R 2 = 0.992, R 2 ext = 0.717) showed good reliability and predictability. All models have been successfully tested by external validation, so all five established models are reliable. The analysis of the different contour maps of different models gives structural information to improve the inhibitory function. Molecular docking results show that the amino acids Met 592, GLU 590, LEU 657, VAL 524, and PHE 589 are the active sites of the tropomyosin receptor TRKs. The results obtained by MD showed that compound 19i could form a more stable complex protein (PDB id: 5KVT). Based on these results, we developed new compounds and their expected inhibitory activities. The results of physicochemical and ADME-Tox properties showed that the four proposed molecules are orally bioavailable, and they are not toxic in the Ames test. Thus, these results would provide modeling information that could help experimental researchers find TRK type I inhibitors more efficiently. Communicated by Ramaswamy H. Sarma

Frequent CD30 Expression in an Emerging Group of Mesenchymal Tumors With NTRK, BRAF, RAF1, or RET Fusions

Neurotrophic tyrosine receptor kinase (NTRK) fusions define infantile fibrosarcomas in young children and NTRK-rearranged spindle-cell tumors in older children and adults, which share characteristic spindle-cell histology and CD34 or S100 protein expression. Similar phenotypes were identified in tumors with BRAF, RAF1, or RET fusions, suggesting a unifying concept of “spindle-cell tumors with kinase gene fusions.” In this study, we investigated CD30 expression in 38 mesenchymal tumors with kinase gene fusions using immunohistochemistry. CD30 was expressed in 15 of 22 NTRK-rearranged tumors and 12 of 16 tumors with BRAF, RAF1, or RET fusions. In total, CD30 was expressed in 27 of the 38 tumors (71%), with >50% CD30-positive cells in 21 tumors and predominantly moderate or strong staining in 24 tumors. CD34 and S100 protein were also expressed in 71% and 69% of the tumors, respectively. In contrast, CD30 was significantly less frequently expressed in other mesenchymal tumor types that histologically mimic kinase fusion–positive tumors (9 of 150 tumors, 6%), of which none showed >50% or predominantly strong staining. Among these mimicking tumors, malignant peripheral nerve sheath tumors occasionally (30%) expressed CD30, albeit in a weak focal manner in most positive cases. CD30 was also expressed in 3 of 15 separately analyzed ALK- or ROS1-positive inflammatory myofibroblastic tumors. Frequent expression of CD30 enhances the shared phenotype of spindle-cell tumors with NTRK and other kinase gene fusions, and its sensitivity seems similar to that of CD34 and S100 protein. Although moderate sensitivity hampers its use as a screening tool, CD30 expression could be valuable to rapidly identify high-yield candidates for molecular workup, particularly in communities that lack routine genetic analysis and/or for tumors with BRAF, RAF1, or RET fusions.