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

BACKGROUND

Members of the neurotrophic tropomyosin receptor kinase (NTRK) gene family, NTRK1, NTRK2, and NTRK3 encode TRK receptor tyrosine kinases. Intra- or inter-chromosomal gene rearrangements produce NTRK gene fusions encoding fusion proteins which are oncogenic drivers in various solid tumors.

METHODS

This study investigated the prevalence of NTRK fusion genes and identified fusion partners in Japanese patients with solid tumors recorded in the Center for Cancer Genomics and Advanced Therapeutics database of comprehensive genomic profiling test.

RESULTS

In the analysis population (n = 46,621), NTRK fusion genes were detected in 91 patients (0.20%). The rate was higher in pediatric cases (<18 years; 1.69%) than in adults (0.16%). NTRK gene fusions were identified in 21 different solid tumor types involving 38 different partner genes including 22 (57.9%) previously unreported NTRK gene fusions. The highest frequency of NTRK gene fusions was head and neck cancer (1.31%) and thyroid cancer (1.31%), followed by soft tissue sarcoma (STS; 0.91%). A total of 97 NTRK fusion gene partners were analyzed involving mainly NTRK1 (49.5%) or NTRK3 (44.2%) gene fusions. The only fusion gene detected in head and neck cancer was ETV6::NTRK3 (n = 22); in STS, ETV6::NTRK3 (n = 7) and LMNA::NTRK1 (n = 5) were common. Statistically significant mutual exclusivity of NTRK fusions with alterations was confirmed in TP53, KRAS, and APC. NTRK gene fusion was detected from 11 STS cases: seven unclassified sarcoma, three sarcoma NOS, and one Ewing sarcoma.

CONCLUSIONS

NTRK gene fusion identification in solid tumors enables accurate diagnosis and potential TRK inhibitor therapy.

Analysis of NTRK mutation and clinicopathologic factors in lung cancer patients in northeast China

OBJECTIVE

NTRK mutations and clinicopathological factors in patients with lung cancer in northeast China were analyzed by next-generation sequencing (NGS), and references were provided for patients with NTRK mutations undergoing targeted therapy in northeast China.

METHODS

A total of 224 specimens in 173 patients with lung cancer were collected. This included 51 patients with matched tissue and whole blood samples,133 tissue samples, 84 whole blood samples, and 7 pleural effusion samples. NGS (520 genes) was used to detected NTRK mutations and clinicopathologic factors.

RESULTS

NTRK mutation was detected in eight patients (8/173, 4.6%), including four NTRK missense mutations (4/173, 2.3%), two NTRK fusion gene mutations (2/173, 1.2%), and two NTRK copy number deletions (2/173, 1.2%). Among the eight patients with NTRK mutations, four were associated with lung cancer driver gene mutations (3/4 EGFR, 1/4ALK); NTRK in two patients was inconsistent in tissue and paired whole blood testing; NTRK missense mutation was detected in one patient, and NTRK copy number deletion was detected in the other; and NTRK wild type was detected in two patients. There was no correlation between NTRK mutation and clinicopathologic factors (including gender, age, pathological type, smoking status, metastasis site).

CONCLUSION

NTRK mutation was only 4.6%, effective fusion gene mutation was 1.2%, and common driver gene mutation in lung cancer was evident in 50% of patients. The results of NTRK were inconsistent with matched tissues and whole blood. Therefore, patients with NTRK mutation should use a variety of specimen types and large target area sequencing (panel) analysis method to provide individualized treatment.