Neurotrophic Tyrosine Receptor Kinase Gene Fusions Research Articles

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.

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 .

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.

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.

GISTs with NTRK Gene Fusions: A Clinicopathological, Immunophenotypic, and Molecular Study.

The most common mutations in gastrointestinal stromal tumors (GISTs) are KIT or PDGFRA mutations. Recently, neurotrophic tyrosine receptor kinase (NTRK) fusions have been reported in WT GISTs, which increased interest in introducing tropomyosin receptor kinase (TRK) inhibitors as treatments for GISTs with NTRK fusions. Hence, we aimed to screen NTRK fusions in WT GISTs; we used fluorescence in situ hybridization (FISH), next-generation sequencing (NGS), and immunohistochemistry (IHC) to screen NTRK fusions in 46 WT GISTs and evaluate each method. We further reviewed NTRK fusion-positive GISTs from the literature and performed clinical and pathological analyses; two GISTs with an ETV6-NTRK3 fusion (5%) were identified, while only one (50%) was positive for Pan-TRK expression. On the other hand, among the six GISTs with Pan-TRK-positive expression, only one (17%) harbored NTRK fusion. The literature review revealed the strong consistency between FISH and NGS and the limited value of Pan-TRK IHC in screening NTRK fusions in GISTs. In addition, the clinical and pathological analysis showed that GISTs with NTRK rearrangement occurred less frequently in the stomach, were more frequently larger in size, and the epithelioid type presented with a higher risk of recurrence. The NTRK3 fusion has been more common than the NTRK1 fusion in GISTs to date; our study identified two ETV6-NTRK3 fusions in 46 WT GISTs. Compared with FISH and IHC, NGS is preferred for screening WT GISTs, including NTRK rearrangements. However, since GISTs with NTRK fusions are rare, further studies including more samples and mechanistic investigations should be conducted in the future.

Testing methods to diagnose TRK fusion cancer - a plain language summary and patient perspective.

This is a plain language summary of a 2022 study published in Cancer Genetics. This study describes the different tests used to detect a rare type of cancer called TRK (tropomyosin receptor kinase) fusion cancer in people taking part in three clinical trials testing the medication larotrectinib. Larotrectinib targets TRK fusion proteins, abnormal proteins that result from abnormal NTRK (neurotrophic tyrosine receptor kinase) gene fusions. People who were shown to have solid tumors containing TRK fusion proteins were able to participate in clinical trials that evaluated larotrectinib. Different testing methods were used to identify participants with TRK fusion cancer. Which test was used depended on different factors such as how commonly NTRK gene fusions are found in a specific cancer type, and the cost and accessibility of the test. Participants with different types of cancer were included in the study, which allowed researchers to identify which TRK fusion proteins were found across various types of tumor. The results of this study provide a guidance for healthcare professionals on the methods used for testing to identify patients that have TRK fusion cancer. By characterizing the types of testing done across cancer types, patients and their caregivers can gain an understanding of the importance of testing. This plain language summary also includes insights and perspectives from a person affected by TRK fusion cancer, and from patient advocates. Clinical Trial Registration: NCT02122913 (ClinicalTrials.gov) Clinical Trial Registration: NCT02637687 (ClinicalTrials.gov) Clinical Trial Registration: NCT02576431 (ClinicalTrials.gov).

CO166 Clinical Outcomes of Patients With Neurotrophic Tyrosine Receptor Kinase (NTRK) Gene Fusion Cancer Treated With Non-Tropomyosin Recepter Kinase Inhibitors: A Systematic Literature Review

For patients with tumors that harbor NTRK gene fusions, TRK inhibitors provide an effective treatment option with a durable response rate as demonstrated in several single arm trials. The effectiveness data of non-TRKi in these patients, however, is very limited. This systematic literature review evaluated the clinical effectiveness of non-TRKi therapies in patients with NTRK fusion cancer.

Çocukluk Çağı Kanserlerinde NTRK Somatik Füzyonları ve Tümör Agnostik Tedavi

Neurotrophic tyrosine receptor kinase (NTRK) gene rearrangements have been recently identified and developed as one of the biomarkers that have been utilized as new targets for cancer therapy. NTRK gene fusions have taken their place in individualized targeted therapy by being used as a predictive (diagnostic) biomarker as well as a treatment target. Selective inhibitors of NTRK fusion proteins have potent efficacy in the treatment of NTRK fusion-positive solid tumors. Detection of these fussions have become important since the finding of new drugs for which U.S. Food and Drug Administration (FDA) granted approval are used on the treatment of patients who has NTRK fussions positive cansers. Clinical trials have shown that first generation tyrosine receptor kinase (TRK) inhibitors, larotrectinib (Vitrakvi, Bayer HealthCare Pharmaceutical Inc, New Jersey, U.S.) and entrectinib (Rozlytrek, Genentech Inc, California, U.S.), have potent efficacy in the treatment of NTRK fusion positive cancers. In the future, with the increase in the number of comprehensive studies on these drugs further information will become available and beneficial.

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

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

Treatment Patterns of Real-World Patients with TRK Fusion Cancer Treated by US Community Oncologists.

Background Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are present across various tumor types with an estimated overall prevalence of less than 1%. Tropomyosin receptor kinase inhibitors (TRKis) block the constitutively activated tyrosine receptor kinase (TRK) fusion protein produced in cancers with NTRK gene fusions (NTRK+) from downstream signaling. Many treatment guidelines now include TRKis as first-line (1L) or subsequent treatment options for TRK fusion cancer.ObjectiveThis study aimed to assess treatment patterns subsequent to a finding of NTRK+ status among patients with TRK fusion cancer.Patients and MethodsThis was a one-time, retrospective, multi-site patient chart abstraction by oncology practices in the USA from June to September 2020. US medical oncologists from the Oncology Provider Extended Network (OPEN) who had treated patients with NTRK+ advanced/metastatic solid tumors abstracted information into electronic case report forms (eCRFs) for adult patients with advanced/metastatic solid tumors and a NTRK+ tumor test result with a known fusion partner. Data abstracted into eCRFs by oncologists included demographic, clinical, and treatment characteristics of patients with advanced/metastatic TRK fusion solid tumors. Responses were summarized using descriptive statistics. Median treatment durations across the lines of therapy were estimated by Kaplan-Meier time to discontinuation.Results A total of 19 medical oncologists abstracted data from 110 patient charts.Median patient age at advanced/metastatic diagnosis was 62 years. The majority of patients were male (58.2%) and White (79.1%). Solid tumor types reported in at least 10% of the study cohort were lung (24.5%), cholangiocarcinoma (13.6%), pancreatic (10.9%), and colorectal (10.0%). Results for patients with hepatobiliary cancers (i.e., cholangiocarcinoma, pancreatic cancer, hepatocellular carcinoma) and colorectal cancer, and appendiceal cancer are also included. Median duration of 1L TRKi therapy was 16.8 months across all solid tumor types, whereas median duration of 1L was 5.6 months among patients receiving non-TRKi therapies (p = 0.017). Among the solid tumor types represented by at least 10% of the study population, median duration of 1L TRKi therapy was only reached in patients with pancreatic cancer (3.3 months). Median duration of TRKi in the second-line (2L) setting was 7.9 months overall, relative to 5.3 months among patients receiving non-TRKi therapies (p = 0.003). Across lung, cholangiocarcinoma, pancreatic, and colorectal cancers, the median durations of 2L TRKi therapy were 14.1, 6.0, 6.1, and 4.1 months, respectively.Conclusion and RelevanceAmong patients with advanced/metastatic TRK fusion solid tumors, medical oncologists reported that approximately two-thirds initiated a TRKi during the study period. Treatment with a TRKi was longer in duration compared to non-TRKi treatment in 1L and 2L therapy. Additional research is needed to gain insight into the association between early TRKi therapy initiation and clinical outcomes in the real-world setting.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11523-022-00909-7.

667P Updated efficacy and safety of larotrectinib in patients with TRK fusion salivary gland tumours

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers of various tumour types, including salivary gland tumours (SGTs). Secretory carcinoma of the salivary gland, a rare subset of SGTs, is characterised by an ETV6-NTRK3 gene fusion found in ≥80% of cases. Larotrectinib is a highly selective, central nervous system-active, tropomyosin receptor kinase (TRK) inhibitor with an objective response rate (ORR) of 92% across 24 evaluable patients (pts) with a variety of SGTs, as of July 2020 (Le et al. Oncologist 2022 [in press]). We report updated efficacy and safety of larotrectinib in pts with TRK fusion SGTs with longer follow-up. Pts with TRK fusion SGTs were identified from two larotrectinib clinical trials (NCT02122913, NCT02576431). Pts received larotrectinib 100 mg twice a day (BID) except for one pt who received 150 mg BID in the phase 1 trial (NCT02122913). Response was assessed by independent review committee (per Response Evaluation Criteria in Solid Tumours v1.1). As of July 2021, 25 pts with TRK fusion SGTs were identified, including 24 with an additional year of follow-up. Median age was 59.0 years (range 28–80). All pts had ETV6-NTRK3 gene fusions. ORR was 84% (95% CI 64–95%): 8 complete responses, 13 partial responses, 2 stable disease and 2 progressive disease. Median time to response was 1.8 months. Median duration of response (DoR) was not reached; median follow-up was 39.6 months. Median progression-free survival (PFS) was 56.0 months (95% CI 30.8–not estimable) at a median follow-up of 41.3 months. Median overall survival (OS) was not reached at a median follow-up of 43.7 months. The 36-month DoR, PFS, and OS rates were 71%, 64%, and 82%. Duration of treatment ranged from 1.0 to 68.0 months. At data cut-off, 8 pts had progressed, with 5 pts continuing treatment post-progression for ≥4 weeks. Treatment-related adverse events (TRAEs) were mostly Grade 1–2. Grade 3–4 TRAEs were reported in 6 pts (24%). There were no treatment discontinuations due to TRAEs. Larotrectinib demonstrated rapid and durable efficacy with a favourable safety profile in pts with TRK fusion SGTs. These data highlight the importance of identifying NTRK gene fusions in pts with SGTs.

463P Efficacy and safety of larotrectinib in a pooled analysis of patients (Pts) with tropomyosin receptor kinase (TRK) fusion cancer with an extended follow-up

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers in multiple tumour types. Larotrectinib, a highly selective TRK inhibitor, demonstrated an investigator-assessed objective response rate (ORR) of 75% across 206 pts with non-central nervous system (CNS) primary, TRK fusion-positive cancers (Hong et al, ASCO 2021). To better determine outcomes in a more mature dataset with a longer follow-up, we report on the first 164 pts enrolled as of February 2019 with a data cut-off of July 2021. Data were pooled from three clinical trials (NCT02576431, NCT02122913, and NCT02637687) of larotrectinib-treated pts with non-CNS primary, TRK fusion cancer. ORR was assessed by independent review committee (IRC) per RECIST v1.1. A total of 164 pts were evaluable for efficacy by IRC. There were 17 different cancer types; the most common were soft tissue sarcoma (42%), thyroid (16%), salivary gland (13%), and lung (8%). Fifty-five (34%) pts were <18 years. Fourteen (9%) pts had CNS metastases at baseline. The overall best ORR was 74% (95% confidence interval [CI] 67–81): 50 (30%) complete response (CR), including 10 (6%) pathological CR, 72 (44%) partial response, 22 (13%) stable disease, 13 (8%) progressive disease and seven (4%) not determined. After longer follow-up, 17 pts (10%) had an improved best overall response over that from the July 2019 data cut. Median time to response was 1.8 months (range 0.9–16.2). Median duration of response was 34.5 months (95% CI 27.6–43.3); median follow-up was 34.1 months. Median progression-free survival was 32.0 months (95% CI 23.4–40.2); median follow-up was 35.8 months. Median overall survival (OS) was not reached; median follow-up was 38.0 months. The 48-month OS rate was 66% (95% CI 57–75). Treatment duration ranged from 0.1 to 67.9 months. Treatment-related adverse events (TRAEs) were mainly Grade 1–2; 32 (20%) pts had Grade 3–4 TRAEs. With an extended follow-up, larotrectinib demonstrated durable and deepening responses, extended survival benefit and a favourable safety profile. This highlights the importance of identifying NTRK gene fusions in cancer pts.

Abstract CT545: Variability in NTRK gene fusions does not appear to impact response to larotrectinib

Abstract Introduction: Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers in various tumor types. Gene fusions arise from inter- and intrachromosomal rearrangements involving the 3’ region of the NTRK gene and the 5’ end of a fusion partner gene, leading to the expression of a constitutively active tropomyosin receptor kinase (TRK) fusion protein. Larotrectinib is a highly selective and central nervous system (CNS)-active TRK inhibitor approved for the treatment of adult and pediatric patients with TRK fusion cancer. Larotrectinib has previously demonstrated an objective response rate (ORR) of 75% in 206 patients with non-primary CNS solid tumors (Hong et al, ASCO 2021). Here, we report on the TRK fusion exon junction organization in patients with TRK fusion cancer receiving larotrectinib. Methods: Patients with non-primary CNS TRK fusion cancer treated with larotrectinib were identified from three clinical trials (NCT02122913, NCT02576431, and NCT02637687). NTRK gene fusion data were determined by local molecular testing. The testing method, NTRK gene fusions, and exon structure were extracted from the molecular pathology reports from 212 patients. The data cut-off was July 20, 2020. Results: TRK fusion exon junction data were available for 80 patients from 14 different tumor types. Median age was 47 years (range 0.5-84 years). The ORR for these patients was 82.5% (95% confidence interval [CI] 72.4-90.1). Patients had gene fusions involving NTRK1 (40%), NTRK2 (4%), or NTRK3 (56%), a pattern similar to that seen in the larger dataset. We detected 20 different NTRK gene fusions; the most common were ETV6-NTRK3, TPM3-NTRK1, and LMNA-NTRK1 detected in 39 (49%), ten (13%), and seven (9%) patients, respectively. There were 12, three, and five different fusion partners associated with NTRK1, NTRK2, and NTRK3, respectively. The majority (12/20; 60%) of fusions were intrachromosomal rearrangement events: 8/12 (67%) related to NTRK1, 2/3 (67%) related to NTRK2, and 2/5 (40%) related to NTRK3. There were 35 different 5’/3’ gene breakpoint combinations: 3’ fusion points were located at NTRK1 exon 8 (n = 2), NTRK1 exon 9 (n = 5), NTRK1 exon 10 (n = 15), NTRK1 exon 11 (n = 6), NTRK1 exon 12 (n = 3), NTRK1 exon 13 (n = 1), NTRK2 exon 15 (n = 2), NTRK2 exon 16 (n = 1), NTRK3 exon 14 (n = 21), and NTRK3 exon 15 (n = 24). For ETV6-NTRK3 fusions, the NTRK3 fusion point was at exon 14 in ten of 11 thyroid carcinomas, but in only three of 13 salivary gland tumors. Conclusions: Among 80 patients with TRK fusion cancer, we detected 20 different NTRK gene fusions, of which 55% occurred in only one patient each. There were 36 different fusion variants. Despite the variability of the fusion structure, larotrectinib was equally efficacious. The large number of potential different fusion partners and involvement of various breakpoints highlight the need for validated and appropriate testing methodologies that are agnostic of 5’ partners and breakpoints. Citation Format: Marc Ladanyi, Sinchita Roy-Chowdhuri, Lauren Ritterhouse, Felix Sahm, Ricarda Norenberg, Kui Shen, Chi Chen, Marc Fellous, 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, Erin R. Rudzinski. Variability in NTRK gene fusions does not appear to impact response to larotrectinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT545.

HGG-18. Long-term efficacy and safety of larotrectinib in paediatric patients with tropomyosin receptor kinase (TRK) fusion-positive primary central nervous system (CNS) tumours

INTRODUCTION: Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers in various tumours. Larotrectinib, a highly selective TRK inhibitor, demonstrated an objective response rate (ORR) of 75% across 206 evaluable patients with various non-primary CNS cancers (Hong et al, ASCO 2021). We report long-term data on larotrectinib-treated paediatric patients with TRK fusion-positive primary CNS tumours. METHODS: Patients aged <18 years with TRK fusion-positive primary CNS tumours enrolled in two clinical trials (NCT02637687, NCT02576431) were included. Larotrectinib was administered at 100 mg/m2 (maximum: 100 mg) twice-daily. Response was investigator-assessed per RECIST v1.1 and RANO. RESULTS: As of July 2021, 28 patients with TRK fusion-positive primary CNS tumours were enrolled, including 14 high-grade and eight low-grade gliomas. Median age at enrolment was 7.0 years (range 1.0–17.0). Twenty-three patients (82%) received prior systemic therapy and 12 (43%) received prior radiotherapy. The ORR was 39% (95% confidence interval [CI] 22–59): three complete responses, eight partial responses, 15 stable disease and two progressive disease. The 24-week disease control rate was 82% (95% CI 63–94). Median duration of response (DoR) was not reached; median follow-up was 25.6 months. Median progression-free survival was 21.9 months (95% CI 9.2–not estimable). Median overall survival (OS) was not reached; median follow-up was 27.6 months. DoR and OS 24-month rates were 53% and 71%, respectively. Treatment duration ranged from 1.0 to 39.0+ months. Treatment-related adverse events (TRAEs) were mostly Grade 1–2. Grade 3–4 events occurred in three patients (increased gamma-glutamyltransferase, hyperglycaemia, hypernatraemia, hyponatraemia and neutropaenia). No patients discontinued treatment due to TRAEs. Fourteen patients progressed on treatment; four continued treatment post-progression for ≥4 weeks. CONCLUSION: Larotrectinib demonstrated high disease control rate, durable responses and a manageable safety profile. These results support testing for NTRK gene fusions in paediatric patients with primary CNS tumours.