NTRK1 Research Articles

10114-GMC-10 EXPERIENCE WITH DIFFERENTIAL NTRK2 FUSION GENE DETECTION IN CANCER MULTI-GENE PANEL TESTING

Abstract INTRODUCTION NTRK fusion gene-positive CNS tumours are rare and there are only two reports in Japan of the use of entrectinib, both in children; This is third case and the first adult case was experienced; the patient was treated by taking entrectinib. The diagnosis and treatment course are reported here and the problems with current oncopanel testings are discussed. CASE Female in her 60s. She came to the hospital on her own with a chief complaint of unstable walk. A mass with a maximum diameter of 8 cm was found in the right temporal occipital lobe. She underwent craniotomy followed by radiotherapy, and in-house panel testing (PleSSision Rapid Neo) detected two BCR-NTRK2 fusion genes. Subsequently, no NTRK gene abnormalities were detected in the foundation-one. Sanger sequencing was performed by ourselves, which could still detect gene mutations, and the patient was submitted to the NCC Onco-Panel at his own expense, where NTRK fusion gene abnormalities could be detected, and after review by the in-house ethics committee, he was started on entrectinib. The tumor showed a shrinking effect and has been stable for eight months. RESULT In the in-house panel test, NTRK2 covered Intron8,9,10,11,12 and two BCR-NTRK2 fusion genes were detected, (Exon1-Exon13) and (Exon1-Exon12). Foundation one covered Intron12 and no genetic variants were detected this time. Subsequently, the NCC OncoPanel test covered Intron 9, 10, 12, 13 and 14 and was able to detect fusion gene mutations. Different results were obtained for NTRK2 fusion gene mutations in each panel test, with different detection coverage. The differences in NTRK fusion gene mutations between tests indicate that it is important to reconfirm which panel test to choose. CONCLUSION Third case in Japan and first adult case of NTRK fusion gene mutation-positive brain tumor; may need to be addressed in NTRK fusion gene detection, recognizing differences in cancer multi-gene panel testing.

10031-GGE-2 GENOMIC ANALYSIS OF MENINGIOMA USING GENE PANEL TESTING

Abstract Recently, cancer gene panel tests have been covered by insurance and their usefulness has been reported. In addition to the cancer gene panel tests covered by insurance, we are conducting the PleSSision-Rapid test, a cancer gene panel test that can measure 143 genes, as a clinical research project. The former has been used for 14 cases brain tumors, and the latter has been used for brain tumors in about 100 cases, respectively. The PleSSision-Rapid test has now completed analysis of 87 cases, with gliomas accounting for 33, meningiomas for 29, and metastatic brain tumors for 14 cases. Tumor mutation burden (TMB) was high in 18 cases, and microsatellite instability was high in none. NTRK gene fusion was observed in 1 case. Of the 29 meningiomas, 9 were male and 20 female, ranging in age from 31 to 79 years (mean 57). Twenty of the cases were located at the skull base. Twenty four were primary cases, whereas 5 were recurrent cases. WHO grade 1, 2, and 3 were 23, 4, and 2, respectively. There was no difference in TMB among grades, and Ki-67 values increased with increasing grade. Comparing grade 1 and grade 2/3, NF2 and KDM6A were found to be significantly different in the rate of gene mutations. Grade 2/3 patients had a significantly higher frequency of copy number aberrations such as genes related to DNA repair, histone modification, and chromatin remodeling, than grade 1 patients,

Detection of NTRK gene fusions in solid tumors: recommendations from a Latin American group of oncologists and pathologists.

NTRK gene fusions have been detected in more than 25 types of tumors and their prevalence is approximately 0.3% in solid tumors. This low prevalence makes identifying patients who could benefit from TRK inhibitors a considerable challenge. Furthermore, while numerous papers on the evaluation of NTRK fusion genes are available, not all countries have guidelines that are suitable for their setting, as is the case with Latin America. Therefore, a group of oncologists and pathologists from several countries in Latin America (Argentina, Chile, Ecuador, Mexico, Peruand Uruguay) met to discuss and reach consensus on how to identify patients with NTRK gene fusions in solid tumors. To do so, they developed a practical algorithm, considering their specific situation and limitations.

Detection of NTRK fusions by RNA-based nCounter is a feasible diagnostic methodology in a real-world scenario for non-small cell lung cancer assessment

NTRK1, 2, and 3 fusions are important therapeutic targets for NSCLC patients, but their prevalence in South American admixed populations needs to be better explored. NTRK fusion detection in small biopsies is a challenge, and distinct methodologies are used, such as RNA-based next-generation sequencing (NGS), immunohistochemistry, and RNA-based nCounter. This study aimed to evaluate the frequency and concordance of positive samples for NTRK fusions using a custom nCounter assay in a real-world scenario of a single institution in Brazil. Out of 147 NSCLC patients, 12 (8.2%) cases depicted pan-NTRK positivity by IHC. Due to the absence of biological material, RNA-based NGS and/or nCounter could be performed in six of the 12 IHC-positive cases (50%). We found one case exhibiting an NTRK1 fusion and another an NTRK3 gene fusion by both RNA-based NGS and nCounter techniques. Both NTRK fusions were detected in patients diagnosed with lung adenocarcinoma, with no history of tobacco consumption. Moreover, no concomitant EGFR, KRAS, and ALK gene alterations were detected in NTRK-positive patients. The concordance rate between IHC and RNA-based NGS was 33.4%, and between immunohistochemistry and nCounter was 40%. Our findings indicate that NTRK fusions in Brazilian NSCLC patients are relatively rare (1.3%), and RNA-based nCounter methodology is a suitable approach for NRTK fusion identification in small biopsies.

Mammary Analog Secretory Carcinoma (MASC) of the oral mucosa with proven ETV6- NTRK3 fusion gene as the gold standard for diagnosis – A case series and literature review

Abstract Introduction/Objective Mammary Analog Secretory Carcinoma (MASC) is a rare type of cancer that occurs in the salivary glands. It is named after its similarity in appearance and behavior to secretory carcinoma of the breast. The incidence of MASC is estimated at 0.3%, with less tha 500 cases reported. The diagnosis of MASC is based on a combination of clinical, radiographic, and histopathologic features. Prognosis is generally good, with a low risk of recurrence and metastasis; its differential diagnosis includes: acinic cell carcinoma, adenocarcinoma (primary or metastatic), mucoepidermoid carcinoma, and low-grade cribriform cystadenocarcinoma. MASC is characterized by ETV6-NTRK3 fusion gene, a translocation between the ETV6 gene on chromosome 12 and the NTRK3 gene on chromosome 15, leading to the fusion of these two genes and the production of a chimeric protein. FISH testing can detect the presence of the ETV6-NTRK3 fusion gene. The detection of the ETV6-NTRK3 fusion gene is highly specific for MASC and can aid in the diagnosis and management of this tumor. In addition, the presence of this gene fusion can have implications for targeted therapy, as drugs that target the NTRK3 gene may be effective in the treatment of MASC. Methods/Case Report This review aims to compare the characteristics of MASC in cases we diagnosed since 2015. Results (if a Case Study enter NA) Cases Case 1 (2015) 68yo Female Right Lower Lip, Biopsy Positive: S100, PAS with and without diastase and mammaglobin Negative: Mucicarmine ETV6 + Case 2 (2016) 54yo Female Right Buccal Mucosa, Biopsy Positive: S100, Mammaglobin Weakly positive: p63 ETV6 + Case 3 (2016) 42yo Male Right Buccal Mucosa, Biopsy Positive: S100, Ck7, Ck5/6, Vimentin Weakly positive: GFAP, p63 Negative: SMA, MSA, Calponin ETV6 + Case 4 (2018) 60yo Female Left Soft Palate, Biopsy Positive: CK7 Weakly positive: GATA-3 Negative: CK20, TTF-1, CDX-2, Napsin A ETV6 + Case 5 (2019) 57yo Female Right Palatal Mucosa, Biopsy Positive: S100, Ck7, Ck5/6, Vimentin Negative: p63, GFAP, Calponin, SMA ETV6 + Conclusion MASC is a very rare salivary gland tumor and the gold standard for its diagnosis is FISH for ETV6 gene rearrangement. All our cases showed ETV6- NTRK3 fusion gene, while 80% (4/5) of the patients were females. S100, mammaglobin and PAS were positive in all tested cases, consistent with previous reports. The histopathological diagnosis of MASC on a biopsy can be challenging; although immunohistochemical stains and morphology may be helpful hints, FISH testing should be considered when MASC is suspected.

Analysis the Relationship between Clonal Hematopoiesis and Cardiovascular Events in Chronic Myeloid Leukemia Based on Next-Generation Sequencing Technology

B ackground With the development and clinical application of high-throughput sequencing technologies and cytogenetics, the genetic complexity of hematopoiesis is better understood. Studies have found that there are gene mutations in hematopoietic stem cells that leading to subsequent clonal hematopoiesis (CH) phenomenon. Moreover, several recent studies have linked the occurrence of cardiovascular events with CH, and individuals with CH had a doubled risk of coronary heart disease and a fourfold increased risk of myocardial infarction. CH also exists in CML, and with the widespread application of second- and third-generation TKIs, the occurrence of cardiovascular adverse events had become one of the difficulties in the management of CML patients. Therefore, analyzing the relationship between additional gene mutations and cardiovascular adverse events in CML patients based on Next-Generation Sequencing (NGS) technology will provide new directions and ideas for the precise management of CML patients. O bjective Analyzing the relationship between clonal hematopoiesis and cardiovascular events in CML patients based on NGS technology. Method Using NGS technology to find hematological tumor-related gene mutations in CML patients, and analyzing their relationship with cardiovascular adverse events in CML patients. R esult A total of 149 CML patients were tested by NGS in this study, and were detected 152 clinically significant mutations. The mutations mainly involved genes related to epigenetic and activated signaling pathways, most of which were detected only in patients with drug resistance/intolerance to tyrosine kinase inhibitors (TKIs). The genes with higher mutation frequency were FAT1, GSTM1, ABL1, CUX1, EP300, ASXL1, TET2, CEBPA and so on. In this study, a total of 40 patients had cardiovascular events during treatment. When analyzing the risk factors of cardiovascular events in CML patients, it was found that patients with cardiovascular events were older [the median age were 58 (23-74) years vs 39 (16-73) years, P<0.001], and the duration of taking second-generation TKIs was also longer [the median time were 38 (0-102) months vs 16 (0-66) months, P=0.001]. When analyzing the relationship between gene mutations and cardiovascular events in CML, it was found that ASXL1, DNMT3A, EZH2 and other genes were more frequently detected in CML patients with cardiovascular events. Among them，DNMT3A mutation was associated with the occurrence of cardiovascular events in CML patients (RR 23.3, P=0.003). In addition, we also found that CCND1, CYP2C19 and NTRK2 gene mutations were only detected in patients without cardiovascular events significantly. C onclusion CML patients with cardiovascular events are older, take second-generation TKIs for a longer time, and have a higher incidence of DNMT3A gene mutation; CCND1, CYP2C19, NTRK2 gene mutation may be a protective factor for cardiovascular events in CML patients.

Pan-TRK immunohistochemistry in gynaecological mesenchymal tumours: diagnostic implications and pitfalls.

NTRK-rearranged sarcomas of the female genital tract mainly occur in the uterus (more commonly cervix than corpus) and are characterized by a "fibrosarcoma-like" morphology and NTRK gene rearrangements. These neoplasms may exhibit histological overlap with other entities and can present diagnostic difficulties without molecular confirmation. Pan-TRK immunohistochemistry was developed to identify tumours harbouring NTRK rearrangements. The aim of this study was to characterize pan-TRK immunohistochemical expression in a large cohort of gynaecological mesenchymal neoplasms and investigate the utility of pan-TRK immunohistochemistry todistinguish NTRK-rearranged sarcoma from its mimics. A total of 473 gynaecological mesenchymal tumours (461 without known NTRK fusions and 12 NTRK-rearranged sarcomas) were selected. Pan-TRK immunohistochemistry (EPR17341, Abcam) was performed on whole tissue sections and tissue microarrays. Molecular interrogation of pan-TRK positive tumours was performed by RNA sequencing or fluorescence in situ hybridization (FISH). Of the 12 NTRK-rearranged sarcomas, 11 (92%) exhibited diffuse (≥70%) cytoplasmic pan-TRK staining with moderate/marked intensity, while the other wasnegative. Eleven (2.4%) additional tumours also exhibited pan-TRK immunohistochemical expression: three low-grade endometrial stromal sarcomas, seven high-grade endometrial stromal sarcomas, and an undifferentiated uterine sarcoma. Molecular confirmation of the absence of NTRK rearrangements was possible in nine of these tumours. Of these nine neoplasms, seven exhibited focal/multifocal (<70%) pan-TRK cytoplasmic staining with weak/moderate intensity. Even though pan-TRK immunohistochemical expression is not entirely sensitive or specific for NTRK-rearranged sarcomas, these neoplasms tend to exhibit diffuse staining of moderate/strong intensity, unlike its mimics. Pan-TRK should be performed in monomorphic uterine (corpus and cervix) spindle cell neoplasms that are negative for smooth muscle markers and hormone receptors and positive for CD34 and/ or S100. Ultimately, the diagnosis requires molecular confirmation.

CTNI-75. EFFICACY AND SAFETY OF LAROTRECTINIB IN PATIENTS WITH TROPOMYOSIN RECEPTOR KINASE (TRK) FUSION PRIMARY CENTRAL NERVOUS SYSTEM (CNS) TUMORS: AN UPDATED ANALYSIS

Abstract BACKGROUND Larotrectinib is a highly selective TRK inhibitor approved for tumor-agnostic use in patients with various tumor types, including primary CNS tumors. Here, we report the independent central review and updated data on patients with TRK fusion-positive primary CNS tumors. METHODS Patients with TRK fusion primary CNS tumors enrolled in two clinical trials (NCT02637687, NCT02576431) were included. Responses were independent review committee (IRC)-assessed. RESULTS As of July 2022, 41 patients were eligible for response assessment by IRC. The median age at enrollment was 11 years (range 1-79). Tumor histologic groups included: high-grade glioma (HGG; n=25), low-grade glioma (LGG; n=9), and other (n=7). Sixteen (39%) patients had received ≥ 2 prior systemic therapies. For all patients, objective response rate (ORR) was 22% (95% CI 11–38): one complete response, eight partial response, 20 stable disease, and 12 progressive disease. For pediatric patients (n=28), the ORR was 29% (95% CI 13–49). For pediatric patients with HGG and LGG, ORRs were 14% (95% CI 2–43) and 57% (95% CI 18–90), respectively. The disease control rates at 24 weeks were 54% (95% CI 37–69) and 71% (95% CI 51–87) for all patients and pediatric patients, respectively. Medians for time to response, duration of response, progression-free survival, and overall survival (OS) were 1.9 months, 12.2 months (95% CI 3.7–not estimable), 11.1 months (95% CI 3.6–19.8), and not reached, respectively. The 48-month OS rate was 52%. Treatment duration ranged from 1 to 50+ months. Treatment-related adverse events (TRAEs) were mostly Grade 1/2. No patients discontinued treatment due to TRAEs. CONCLUSION Larotrectinib demonstrated rapid, durable responses and a manageable safety profile in patients with TRK fusion primary CNS tumors. This supports the wider adoption of next-generation sequencing panels that include NTRK gene fusions when testing patients with CNS tumors.

EP13.02-03 Entrectinib Amazing Efficacy in a Case of Lung Atypical Carcinoid with NTRK Gene Fusion

EP13.02-03 Entrectinib Amazing Efficacy in a Case of Lung Atypical Carcinoid with NTRK Gene Fusion

Novel, clinically relevant genomic patterns identified by comprehensive genomic profiling in ATRX-deficient IDH-wildtype adult high-grade gliomas

Glioblastomas are the most common IDH-wildtype adult high-grade gliomas, frequently harboring mutations in the TERT gene promoter (pTERT) and utilizing the subsequent telomerase overexpression for telomere length maintenance. However, some rare cases show loss of ATRX and use alternative mechanisms of telomere lengthening. In this study, we performed the first complex genomic analysis specifically concentrating on the latter subgroup. Comprehensive genomic profiling of 12 ATRX-deficient and 13 ATRX-intact IDH-wildtype adult high-grade gliomas revealed that ATRX and pTERT mutations are mutually exclusive. DNMT3A alterations were confined to ATRX-deficient, while PTEN mutations to ATRX-intact cases. RAS–MAPK pathway alterations, including NF1 mutations, were more characteristic in the ATRX-deficient group. Variants of genes related to homologous recombination repair showed different patterns of affected genes. Two ATRX-deficient tumors with high tumor mutational burden and mismatch repair deficiency were found. One of these contained a novel fusion involving the NTRK2 and LRRFIP2 genes, while the other showed loss of MSH2 and MSH6 without genetic alterations in the encoding genes suggesting an epigenetic background. Genetic characteristics of ATRX-deficient IDH-wildtype adult high-grade gliomas suggest that these tumors are particularly intriguing targets of potential future therapeutic interventions including immunotherapies combined with MAPK pathway inhibition and DNA repair inhibitors.

Identification of dual STRN-NTRK2 rearrangements in a high grade sarcoma, with good clinical response to first-line larotrectinib therapy

BackgroundAmong the three NTRK genes, NTRK2 possesses a tremendous structural complexity and involves tumorigenesis of several types of tumors. To date, only STRN and RBPMS are identified in the fusion with NTRK2 in adult soft tissue tumors. More recently, the highly selective Trk tyrosine kinases inhibitors, including larotrectinib and entrectinib, have shown significant efficacy for treating tumors harboring NTRK fusions and were approved by FDA.Case presentationWe report a case of sarcoma in a 35-year-old female harboring two STRN-NTRK2 gene fusions, with a good clinical response to first-line larotrectinib treatment. Core biopsy of the 16.5 cm gluteal mass showed a high-grade mesenchymal neoplasm with features reminiscent of a solitary fibrous tumor, but negative for STAT6. In-house next-generation sequencing gene fusion panel showed two in-frame STRN-NTRK2 fusions, which contain the same 5’ partner sequence (exon 1–3) of STRN, and the 3’ fusion partner starting from either the exon 15 or the exon 16 of NTRK2. Due to the large size and location of the tumor, first-line neoadjuvant therapy with larotrectinib was initiated. The patient has an excellent clinical response with an 83% tumor size reduction by imaging. The tumor was subsequently completely resected. After 130 days, larotrectinib was reinitiated for lung metastasis (up to 7 cm), and a complete resolution was achieved. When compared with NTRK1 and NTRK3, NTRK2 fusions are the least common. Of note, the only other report in the literature on NRTK2 fusion-positive sarcoma also showed solitary fibrous tumor (SFT)-like morphology, and the patient responded well to larotrectinib as the second line adjuvant therapy.ConclusionsIn conclusion, the identification of NTRK2 fusions in patients with soft tissue tumors could significantly improve the clinical outcome through selective NTRK inhibitor therapy, especially in the first-line setting. Prompt RNA-based NGS testing at initial diagnosis may benefit these patients. Our case is among the first few in the literature on NTRK2 fusion sarcoma with first-line larotrectinib therapy in the primary and metastatic setting, with good clinical response and minimal side effects.

THU679 Genetic Alterations In Children And Young Adults Differentiated Thyroid Cancer

Abstract Disclosure: G.J. Machado: None. A.O. Telles: None. J.L. von Ammon: None. R.R. da Matta: None. F.E. Beltrão: None. F. Hecht: None. A.R. da Paz: None. G.D. Lopes: None. L.F. Rios: None. H.E. Ramos: None. Introduction: Children and young adults (CAYA) differentiated thyroid cancer (DTC) differs from adult DTC in its underlying genetics features. In this report, we studied these aspects in 79 cases of CAYA DTC. Objective: To determine the prevalence of molecular alterations in paraffin-embedded samples of DTC from children, adolescents and young adults treated at the centers participating in the study. Methods: Tumor samples obtained from 79 CAYA patients (age &amp;lt; 21 years) screened with DTC between January 2010 and Mach 2021 were retrospectively recruited from four health centers from the state of Bahia and Paraíba, Brazil. Demographic and anatomopathological data were reviewed by a pathologist. Tumor DNA was extracted from paraffin-embedded samples and directed to analysis through next-generation sequencing (NGS), where it was submitted to the HotSpot panel to determine point mutations, and to the Fusion Panel to identify gene fusions. Results: The median age at diagnosis observed in the sample studied was 18 years, with patients ranging between 6 and 21 years. Thirty patients (38%) were under 18 years and forty-nine (62%) were aged between 18 and 21 years. The vast majority were female (77%), with only 18 cases male (23%). Overall: 21/79 (26.6%) results were inconclusive, 21/79 (26.6%) mutated and 37/79 (46.8%) wild type. Among the mutated, 10/21 (47.6%) cases were positive for BRAF mutation, 08/21 (38.1%) for EGFR, 04/21 (19.0%) for KRAS, 03/21 (14 .3%) for NRAS and 01/21 (4.8%) for PIK3CA, with occurrence of simultaneous point mutations. Of the 10 mutations found in the BRAF gene, 60% of them were V600E. The remaining percentage was characterized by less common genetic alterations in this gene, the so-called BRAFnon-V600E, were identified: 01 BRAFG464R mutation, 01 BRAFG469E and 02 BRAFS467L. As for molecular analysis to detect gene fusions: 39/74 (52.7%) had inconclusive results, 10/74 (13.5%) were positive for a rearrangement and 25/74 (33.8%) were classified as wild type. Among the positive cases for gene fusions: 03 were of the RET gene (01 CCDC6::RET or RET/PTC1, 01 NCOA4::RET or RET/PTC3, and 01 TRIM24::RET or RET/PTC6); 04 were from the NTRK gene (03 ETV6::NTRK3 and 01 TPR::NTRK1); 02 PAX8::PPARG merges; and 01 STRN::ALK. Conclusion: In our CAYA patients: (i) BRAF gene mutations were the most prevalent, followed by EGFR, KRAS, NRAS and PIK3CA, (ii) novel BRAFnon-V600E were identified, (iii) 13,5% had gene rearrangements which were more frequent in subjects under 18 years old. *Supported by Bayer (21641) Presentation: Thursday, June 15, 2023

THU151 Undiagnosed MODY In Case Of Morbid Obesity

Abstract Disclosure: A. Abdulkader: None. S.B. Ten: None. MODY is suspected in nonobese subjects with hyperglycemia, negative islet cell antibodies, and a family history of diabetes. Children with morbid obesity and diabetes can still have MODY and require different treatment. Case report The patient was born after a pregnancy complicated with gestational diabetes, treated with insulin, BW 9 1/2 lbs. He had early onset obesity from 3 yrs. of age. At 8 yrs., he developed impaired glucose tolerance, elevated triglycerides, low HDL, and fatty liver. He developed diabetes at 11 yrs. and was treated with Insulin, but treatment was not effective, Hb A1c was 11.4%, and BMI was 51.8 kg/m2. At 12 yrs., he was diagnosed with MODY on the base of normal C-peptide, negative islet cell AB, strong family history of diabetes: mother, uncle and MGM had diabetes. Insulin was discontinued. Glyburide and Metformin were started that improved his glucose level significantly. Hb A1c improved to 6.2%. Diet was changed, physical exercises were added, and he lost 25 lbs., BMI improved to 44.8 kg/m2. His mother, 46 yrs. old, was diagnosed with diabetes type 1 at 18 yrs. and treated with Insulin. She also had morbid obesity with BMI 48 kg/m2. She developed diabetic neuropathy, nephropathy, and had amputation of the left leg below the knee, eGFR 44 mL/min/1.73m2, Hb A1c 10.5%. She was diagnosed with MODY on the base of normal C-peptide 3.21 ng/mL, negative islet cell AB, family history of diabetes: her mother, brother, son have diabetes. Glyburide and pioglitazone were started, Insulin total daily dose was decreased from 90 units to 15 units a day. Her Hb A1c improved to 6 %, insulin was discontinued. She underwent Roux-en-Y Gastric Bypass surgery, lost 30 lbs. BMI improved to 42 kg/m2, Hb A1c became 5.3%. Her current glucose level is normal on Glyburide 2.5 mg and pioglitazone 7.5 mg daily. Results: Patient and his mother had heterozygous gene polymorphism in GLIS3, c.951G&amp;gt;T (p.Glu317Asp). This sequence replaces glutamic acid with aspartic acid at codon 317 of the GLIS3 protein (p.Glu317Asp). GLIS3 is a variant of MODY and is a transcriptional factor in beta cell differentiation and insulin production. Patient and mother had pathogenic heterozygous variant of KSR2 gene, c.1622del, resulting in a frameshift and premature protein termination (p.Lys541Serfs*27). Pathogenic variants in KSR2 are associated with obesity and insulin resistance. Patient was also heterozygous in the NTRK2 gene for a sequence variant c.500C&amp;gt;A, which is predicted to result in the amino acid substitution p.Ser167Tyr, also associated with obesity. Conclusion Genetic analysis of MODY is necessary even in cases of diabetes with morbid obesity, negative islet cell AB, positive family history of diabetes. Diagnosis of MODY helps provide individualized treatment and avoid complications secondary to unnecessary treatment with insulin. Presentation: Thursday, June 15, 2023

211P Cost-efficient detection of NTRK1, NTRK2 and NTRK3 gene rearrangements using the test for 5’/3’-end unbalanced expression: The analysis of 8075 patients

211P Cost-efficient detection of NTRK1, NTRK2 and NTRK3 gene rearrangements using the test for 5’/3’-end unbalanced expression: The analysis of 8075 patients

122P Molecular testing, treatment, and response of patients with advanced solid tumors harboring an NTRK gene fusion: Second interim results of the REALTRK registry

122P Molecular testing, treatment, and response of patients with advanced solid tumors harboring an NTRK gene fusion: Second interim results of the REALTRK registry

The efficacy of the TRK inhibitor entrectinib in patients with extracranial &lt;i&gt;NTRK&lt;/i&gt; fusion-positive tumors

Somatic translocations involving the NTRK genes occur in 0.34–2.2% of all malignant neoplasms in children. TRK inhibitors whose efficacy has been demonstrated in prospective clinical studies expand treatment options for patients with solid tumors harboring NTRK gene rearrangements. The aim of our study was to summarize the first Russian experience with the use of the TRK inhibitor entrectinib in patients with extracranial NTRK fusion-positive solid tumors included in the compassionate use program. This study was approved by the Independent Ethics Committee and the Academic Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. The study included 8 patients who had been treated at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology and the N.N. Blokhin National Medical Research Center of Oncology. The main criteria for inclusion in the compassionate use program were a confirmed rearrangement of either NTRK1/2/3 genes in a solid tumor in patients with unresectable disease for whom no effective standard systemic therapy was available, progressive or recurrent disease during therapy prescribed according to the established diagnosis, risk group and risk stratification criteria, and the infeasibility of non-mutilating radical surgery. The median age at diagnosis was 4.3 months (range 1.2–83.6). The male to female ratio was 1:1. The primary site distribution was as follows: head and neck (n = 6; 75%), chest wall (n = 1; 12.5%), pelvis (n = 1; 12.5%). None of the patients had regional lymph node involvement or distant metastases at diagnosis. The distribution by histology (according to histopathology reports) was as follows: infantile fibrosarcoma (n = 4; 50%), undifferentiated round cell sarcoma, low-grade (n = 1; 12.5%), undifferentiated spindle cell sarcoma, high-grade (n = 1; 12.5%), NTRK-rearranged spindle cell sarcoma, low-grade (n = 1; 12.5%), spindle cell tumor associated with an NTRK rearrangement (n = 1; 12.5%). Immunohistochemistry (IHC) with a pan-Trk monoclonal antibody was performed in 7/8 (87.5%) patients. Pan-Trk IHC was positive in 4/7 (57%) patients. Rearrangements in the NTRK1 and NTRK3 genes were confirmed in all the patients. The final methods used for the detection of fusion transcripts were as follows: reverse transcription polymerase chain reaction (n = 4; 50%) and RNA-based next-generation sequencing (n = 4; 50%). NTRK1 and NTRK3 gene translocations were detected in 3/8 (37.5%) and 5/8 (62.5%) patients, respectively. The following fusion transcripts were identified: ETV6::NTRK3 (n = 4), DIP2C::NTRK3 (n = 1), TPR::NTRK1 (n = 1), TPM3::NTRK1 (n = 1), MYH10::NTRK1 (n = 1). One (12.5%) patient received entrectinib as first-line therapy, other patients (7/8, 87.5%) received entrectinib as secondor subsequent-line therapy. Three (37.5%) patients had undergone surgery before treatment with entrectinib: 2 had R2 resection, 1 had R0/R1 resection (resection margins were not evaluated). None of the patients received radiation therapy. The median duration of entrectinib therapy at the time of analysis was 11.8 months (range 2.3–20.1). Delayed surgery was performed in 2/8 patients; according to the histopathology reports, they achieved grade IV pathomorphosis. Three patients experienced adverse events during treatment with entrectinib. The median time to adverse events was 0.23 months (range 0.2–7.96). Three patients required temporary interruption in treatment to relieve symptoms, a subsequent dose reduction by one dose level was necessary when resuming therapy in two patients. The median follow-up since diagnosis was 19.5 months (range 14.9–75.0). All the patients included in our analysis were alive, three of them had no radiologic evidence of disease. Fifty percent of the patients completed targeted therapy, another 50% of the patients continued treatment with entrectinib. Complete and very good partial response was achieved in 3/8 and 2/8 patients, respectively. Partial response, minor partial response and stable disease were observed in one patient each. These results indicate high efficacy and safety of entrectinib in pediatric patients with extracranial NTRK fusion-positive solid tumors. Further studies are needed to determine the therapeutic potential of TRK inhibitors in the treatment of different solid malignant neoplasms in children and to assess long-term treatment results.

Larotrectinib efficacy and safety in adult patients with tropomyosin receptor kinase fusion sarcomas.

Larotrectinib, a first-in-class, highly selective tropomyosin receptor kinase (TRK) inhibitor, has demonstrated efficacy in adult and pediatric patients with various solid tumors harboring NTRK gene fusions. This subset analysis focuses on the efficacy and safety of larotrectinib in an expanded cohort of adult patients with TRK fusion sarcomas. Patients (≥18years old) with sarcomas harboring NTRK gene fusions were identified from three clinical trials. Patients received larotrectinib 100mg orally twice daily. Response was investigator-assessed per RECIST v1.1. Data cutoff was July 20, 2021. At the data cutoff, 36 adult patients with TRK fusion sarcomas had initiated larotrectinib therapy: two (6%) patients had bone sarcomas, four (11%) had gastrointestinal stromal tumors, and 30 (83%) had soft tissue sarcomas. All patients were evaluable for response and demonstrated an objective response rate of 58% (95% confidence interval, 41-74). Patients responded well to larotrectinib regardless of number of prior lines of therapy. Adverse events (AEs) were mostly grade 1/2. Grade 3 treatment-emergent AEs (TEAEs) occurred in 15 (42%) patients. There were no grade 4 TEAEs. Two grade 5 TEAEs were reported, neither of which were considered related to larotrectinib. Four (11%) patients permanently discontinued treatment due to TEAEs. Larotrectinib demonstrated robust and durable responses, extended survival benefit, and a favorable safety profile in adult patients with TRK fusion sarcomas with longer follow-up. These results continue to demonstrate that testing for NTRK gene fusions should be incorporated into the clinical management of adult patients with various types of sarcomas. Tropomyosin receptor kinase (TRK) fusion proteins result from translocations involving the NTRK gene and cause cancer in a range of tumor types. Larotrectinib is an agent that specifically targets TRK fusion proteins and is approved for the treatment of patients with TRK fusion cancer. This study looked at how well larotrectinib worked in adult patients with sarcomas caused by TRK fusion proteins. Over half of patients had a durable response to larotrectinib, with no unexpected side effects. These results show that larotrectinib is safe and effective in adult patients with TRK fusion sarcomas.

B-246 The Evaluation of Actionable Mutations By Multiplex Analysis Using IntelliPlex® Lung Cancer Panel for Non-Small Cell Cancer Management

Abstract Background Understanding the genetic alterations which occur in genes associated with various cancers can improve therapy outcomes by promoting tailored treatments for each patient. Molecular profiling is therefore a crucial tool for precision medicine and enables for a personalized approach to cancer management. Current guidelines for molecular testing of Non-Small Cell Lung Cancer (NSCLC) patients involves treatment selection of a targeted Tyrosine Kinase Inhibitor based on the minimal testing of EGFR, ALK and ROS1 genes and strongly recommending the additional testing of KRAS, BRAF, MET, RET, NTRK and ERBB2 (Her2) genes to fully evaluate the patient’s mutational status. Method The IntelliPlex Lung Cancer Panel, based on PlexBio’s multiplexing πCode® technology, is an in vitro molecular amplification assay intended for the qualitative identification of 74 DNA mutations in the KRAS, NRAS, PIK3CA, BRAF, EGFR, HER2, MEK1 and AKT1 genes and 28 gene variants of the ALK, ROS1, RET, NTRK1 and MET genes. The assay is suitable for the use with formalin-fixed paraffin-embedded (FFPE) tumor tissues from NSCLC patients. The performance of IntelliPlex Lung Cancer Panel was evaluated on FFPE specimens by comparing the results with two commercially available molecular amplification assays. Discrepant samples were resolved by a corresponding digital PCR method kit. Results The IntelliPlex Lung Cancer Panel can detect DNA mutations at very low allele frequencies (as low as 0.1%) while only requiring DNA quantities of 10ng. Most RNA rearrangements are detected with 10 or more copies present in the sample while only low RNA input quantities (50 ng) are required. The IntelliPlex Lung Cancer Panel can analyze the mutational status of 102 targets in less than 5.5 h from sample to results and allows screening of up to 48 samples in parallel. Among 50 FFPE DNA specimens tested, the overall agreement for EGFR and KRAS mutations between IntelliPlex system and the comparison method were both found to be 98%. And the overall agreement after resolved the discrepancies by digital PCR was 100%. Conclusion The multiplex amplification and detection capabilities of the IntelliPlex Lung Cancer Panel provides a comprehensive and efficient way to evaluate the individual mutational status from lung cancer patients with high sensitivity and specificity. Accurate genetic analysis provides valuable information which can support precision medicine decisions for better cancer management. This can also be used further with non-invasive whole blood sampling (i.e., “liquid biopsy”) for subsequent treatment monitoring.

Cost-Efficient Detection of NTRK1/2/3 Gene Fusions: Single-Center Analysis of 8075 Tumor Samples.

The majority of NTRK1, NTRK2, and NTRK3 rearrangements result in increased expression of the kinase portion of the involved gene due to its fusion to an actively transcribed gene partner. Consequently, the analysis of 5'/3'-end expression imbalances is potentially capable of detecting the entire spectrum of NTRK gene fusions. Archival tumor specimens obtained from 8075 patients were subjected to manual dissection of tumor cells, DNA/RNA isolation, and cDNA synthesis. The 5'/3'-end expression imbalances in NTRK genes were analyzed by real-time PCR. Further identification of gene rearrangements was performed by variant-specific PCR for 44 common NTRK fusions, and, whenever necessary, by RNA-based next-generation sequencing (NGS). cDNA of sufficient quality was obtained in 7424/8075 (91.9%) tumors. NTRK rearrangements were detected in 7/6436 (0.1%) lung carcinomas, 11/137 (8.0%) pediatric tumors, and 13/851 (1.5%) adult non-lung malignancies. The highest incidence of NTRK translocations was observed in pediatric sarcomas (7/39, 17.9%). Increased frequency of NTRK fusions was seen in microsatellite-unstable colorectal tumors (6/48, 12.5%), salivary gland carcinomas (5/93, 5.4%), and sarcomas (7/143, 4.9%). None of the 1293 lung carcinomas with driver alterations in EGFR/ALK/ROS1/RET/MET oncogenes had NTRK 5'/3'-end expression imbalances. Variant-specific PCR was performed for 744 tumors with a normal 5'/3'-end expression ratio: there were no rearrangements in 172 EGFR/ALK/ROS1/RET/MET-negative lung cancers and 125 pediatric tumors, while NTRK3 fusions were detected in 2/447 (0.5%) non-lung adult malignancies. In conclusion, this study describes a diagnostic pipeline that can be used as a cost-efficient alternative to conventional methods of NTRK1-3 analysis.

Uterine Sarcoma With EML4::NTRK3 Fusion: A Spectrum of Mesenchymal Neoplasms Harboring Actionable Gene Fusions.

NTRK gene fusions are part of a paradigm shift in oncology, arising as one of the main genomic alterations with actionability in the so-called "agnostic setting." In gynecologic pathology, the recent description of uterine sarcoma resembling fibrosarcoma and with NTRK rearrangements (NTRK-rearranged uterine sarcoma) highlights the importance of recognizing clinicopathological cues that can lead to genomic profiling. Herein, we report the case of a 43-year-old woman presenting with vaginal bleeding and pelvic mass. Histopathology of the tumor showed moderately atypical spindle cells arranged in long fascicles reminiscent of fibrosarcoma, along with immunohistochemical positivity for S100, CD34, and pan-tropomyosin receptor kinase. This prompted RNA-sequencing and the finding of a rare EML4::NTRK3 fusion. Clinical, histologic, and molecular findings are described, in addition to discussions regarding differential diagnoses and possible implications of the findings in clinical practice.