Activity of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) in patients (pts) with NSCLC with uncommon EGFR mutations: A real-world cohort study (UpSwinG).

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 9072-9072
Author(s):  
Satoru Miura ◽  
Te-Chun Hsia ◽  
Jen-Yu Hung ◽  
Hyun Ae Jung ◽  
Jin-Yuan Shih ◽  
...  
Keyword(s):  
Real World ◽  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Egfr Mutations ◽  
Pathology Reports ◽  
Multi Center Study ◽  
Line Of Therapy ◽  
Ecog Ps ◽  
Egfr Tki ◽  
Egfr Tkis

9072 Background: EGFR TKIs are an established treatment (tx) option for pts with EGFR mutation-positive NSCLC with common mutations (Del19 or L858R); however, 7–23% of NSCLC tumors harbor uncommon EGFR mutations, where EGFR TKI efficacy is less established. These mutations are highly heterogeneous, and developments in detection by NGS are helping to identify mutations with little or no clinical data. Methods: In this non-interventional, global, multi-center study (NCT04179890), existing medical or electronic health records were identified for consecutive EGFR TKI-naïve pts with uncommon EGFR mutations (T790M, ex20ins, major uncommon [G719X, L861Q or S768I], ‘other’ or compound mutations) treated with erlotinib, gefitinib, afatinib, osimertinib or other systemic therapy. Endpoints were time to tx failure (TTF), ORR, OS and duration of response (DoR). Results: Overall, 246 pts (median age: 69.5 yrs; Asian: 84%; brain metastases: 8%; ECOG PS ≥2: 16%) were recruited from 9 countries. Most pts (n=226; 92%) received an EGFR TKI as 1st-line therapy; 132 (54%), 105 (43%) and 7 (3%) received afatinib, 1st-gen TKIs and osimertinib, respectively. 57% of pts received >1 line of therapy. Most pts (73%) had a major uncommon mutation, 9% had other mutations and 33% had a compound mutation; these were detected using PCR (75%) or sequencing (25%), mainly based on tissue biopsy (86%). Pathology reports varied in quality, often lacking detail on specific mutations e.g. 21% of ex18 and 72% of ex20ins were undefined. Median TTF and OS with EGFR TKIs were 9.9 and 24.4 mos; ORR was 42%. In pts treated with 1st-line chemotherapy (n=20), median TTF and ORR were 6.6 mos and 41%. Outcomes were most favorable in major uncommon and compound mutations (Table). TTF appeared to be higher with afatinib vs 1st-gen EGFR TKIs. In most mutation categories, median OS was >2 yrs, possibly reflecting high subsequent therapy uptake. Conclusions: In a real-world setting, EGFR TKIs were the preferred tx option in pts with uncommon EGFR mutations; strongest outcomes were seen in major uncommon and compound mutations, and in pts treated with afatinib. Data were in line with recent analyses of afatinib in uncommon mutations. Tx with an EGFR TKI should be considered as standard for most pts with uncommon mutations. Optimal tx for pts with uncommon mutations requires improvements in pathology reports, with more emphasis on NGS methodology and precise definition of mutations. Clinical trial information: NCT04179890. [Table: see text]

scholarly journals Preclinical characterization of mobocertinib highlights the putative therapeutic window of this novel EGFR inhibitor to EGFR exon 20 insertion mutations

2020 ◽  
Author(s):  
Pedro E. N. S. Vasconcelos ◽  
Ikei S. Kobayashi ◽  
Susumu S. Kobayashi ◽  
Daniel B. Costa
Keyword(s):  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Egfr Mutations ◽  
Therapeutic Window ◽  
Mechanisms Of Resistance ◽  
Egfr Tyrosine Kinase Inhibitors ◽  
Exon 20 ◽  
Egfr Tki ◽  
Insertion Mutations ◽  
Egfr Tkis

AbstractBackgroundEpidermal growth factor receptor (EGFR) exon 20 insertion mutations account for 10% of all EGFR mutations and are mostly insensitive to approved EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Novel EGFR-TKIs have been developed or repurposed for these mutants. A limited number of preclinical studies have detailed these EGFR-TKIs. We sought to use commercially available mobocertinib (TAK-788) to characterize the preclinical therapeutic window of this EGFR-TKI against EGFR mutations and to probe possible on-target mechanisms of resistance (EGFR-C797S).MethodsWe used models of EGFR mutations to probe representative 1st, 2nd, 3rd generation, and in-development EGFR exon 20-active (poziotinib, mobocertinib) TKIs. We also introduced EGFR-C797S to these models to identify mechanisms of resistance.ResultsCells driven by the most common EGFR exon 20 insertion mutations (A767_V769dupASV, D770_N771insSVD, H773_V774insH and others) were inhibited by in-development EGFR TKIs at doses below those affecting EGFR-wildtype; albeit more common EGFR mutations (exon 19 deletions and L858R) were inhibited more readily by mobocertinib and poziotinib. Mobocertinib was able to inhibit phosphorylation of EGFR in multiple preclinical models. The presence of EGFR-C797S led to >200-fold resistance in proliferation assays probing mobocertinib and osimertinib. Review of clinical studies of mobocertinib disclosed responses that could be lasting.ConclusionsThis is one of the initial reports to characterize the novel EGFR TKI mobocertinib and highlights its broad activity against EGFR mutants plus the therapeutic window to EGFR exon 20 insertion mutations; as well as EGFR-C797S as a possible mechanism of resistance. Further clinical development of mobocertinib merits continuation.

scholarly journals First- or second-generation epidermal growth factor receptor tyrosine kinase inhibitors in a large, real-world cohort of patients with non-small cell lung cancer

2021 ◽  
Vol 13 ◽  
pp. 175883592110357
Author(s):  
Allen Chung-Cheng Huang ◽  
Chi-Hsien Huang ◽  
Jia-Shiuan Ju ◽  
Tzu-Hsuan Chiu ◽  
Pi-Hung Tung ◽  
...  
Keyword(s):  
Real World ◽  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Egfr Mutations ◽  
Rank Test ◽  
Third Generation ◽  
Log Rank Test ◽  
Epidermal Growth ◽  
Tki Treatment ◽  
Egfr Tki

Background: There are limited comparisons of first- and second-generation EGFR tyrosine kinase inhibitors (TKIs) in large, real-world cohorts of non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor ( EGFR) mutations. Methods: Patients with advanced NSCLC ( N = 612) with common EGFR mutations receiving first-line gefitinib/erlotinib and afatinib were grouped and propensity-score matched. Progression-free survival (PFS), overall survival (OS) and secondary T790M mutations were analyzed. Results: The gefitinib/erlotinib and afatinib groups each contained 206 patients after matching. Compared with gefitinib/erlotinib, patients receiving afatinib achieved longer median PFS (16.3 versus 14.2 months; log-rank test p = 0.020) and had a lower risk of progression [hazard ratio (HR) 0.73 (95% confidence interval (CI), 0.57–0.94); p = 0.017]. Median OS (37.3 versus 34.2 months; log-rank test p = 0.500) and reduction in risk of death [HR 0.89 (95% CI, 0.65–1.23); p = 0.476] did not differ significantly between groups. T790M positivity was significantly higher in the gefitinib/erlotinib than afatinib group (70.9% versus 44.6%, p < 0.001). Multivariate analysis demonstrated that afatinib was independently associated with lower T790M positivity [odds ratio (OR) 0.27 (95% CI, 0.14–0.53); p < 0.001], whereas ⩾12 months PFS after EGFR-TKI treatment [OR 3.00 (95% CI, 1.56–5.98); p = 0.001] and brain metastasis [OR 2.12 (95% CI, 1.08–4.26); p = 0.030] were associated with higher T790M positivity. Sequential third-generation EGFR-TKI treatment was administered to 63 patients, in whom median OS after the second–third-generation and first–third-generation EGFR-TKI sequences were 38.8 and 29.1 months, respectively. Conclusion: Compared with gefitinib/erlotinib, afatinib had a higher treatment efficacy and a lower secondary T790M positivity in a large, real-world cohort of Asian patients with EGFR-mutated NSCLC.

Understanding real-world outcomes in patients with NSCLC who progress on 1st-/2nd-generation EGFR TKIs.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e20589-e20589
Author(s):  
Ancilla Fernandes ◽  
Karen E Skinner ◽  
Mark Stephen Walker ◽  
Melissa Pavilack ◽  
Ari M. Vanderwalde
Keyword(s):  
Treatment Period ◽  
Real World ◽  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Retrospective Chart Review ◽  
Progression Free Survival ◽  
2Nd Generation ◽  
Egfr Tyrosine Kinase Inhibitors ◽  
Tki Treatment ◽  
Egfr Tkis

e20589 Background: Epidermal growth factor receptor (EGFR)tyrosine kinase inhibitors (TKIs) are recommended for patients (pts) with EGFR mutation ( EGFRm) positive non-small cell lung cancer (NSCLC). Limited data are available for real-world outcomes in pts who experience progression on 1st-/2nd-generation EGFR TKIs, which was the focus of this study. Methods: A retrospective chart review of pts with advanced NSCLC (stage IIIb/IV) from 10 US community oncology practices was conducted. Patients were included if they were diagnosed 1/1/2008—1/1/2015, were treated with erlotinib or afatinib (TKIs) either first line (1L) or second line (2L), and had disease progression (per clinician’s assessment) prior to 10/31/2015. Pts were classified into cohorts based on TKI initiation (1L or 2L) and EGFRm status. Progression-free survival (PFS) and overall survival (OS) were evaluated for the TKI treatment period and the post-progression period. Results: The study included 364 pts: 77.7% white, 17.3% African American; mean (SD) age 66.3 (11.3) years. PFS and OS were longer for 1L and EGFRm+ pt cohorts during the TKI treatment period. After progression, 25.3% (80/316) pts continued TKI, while around half received chemotherapy (56.3%; 178/316). The effects of other variables evaluated as predictors of PFS and OS were largely nonsignificant. Conclusions: Outcomes were worse after progression irrespective of EGFRm status and whether TKI was initiated 1L or 2L. This finding highlights the need for therapeutic options that improve outcomes in pts after progression on a 1st-/2nd-generation EGFR TKI. [Table: see text]

Impact of HER2 aberrations on EGFR-TKI treatment outcomes in lung tumors harboring EGFR mutations: A HER2-CS STUDY subset analysis.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 9056-9056 ◽  
Author(s):  
Hiroe Kayatani ◽  
Keisuke Aoe ◽  
Kadoaki Ohashi ◽  
Hiroshige Yoshioka ◽  
Akihiro Bessho ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor Receptor ◽  
Egfr Mutations ◽  
Her2 Protein ◽  
Epidermal Growth ◽  
Tki Treatment ◽  
Egfr Mutant ◽  
Egfr Mutated ◽  
Egfr Tki ◽  
Egfr Tkis

9056 Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are a key treatment for EGFR-mutated non-small-cell lung carcinoma (NSCLC). To date, a biomarker to predict whether NSCLC will exhibit a short- or long-term response to first- or second-generation EGFR-TKIs has not been established for clinical use. Human epidermal growth factor receptor-2 (HER2) aberrations are mechanisms for acquired resistance to EGFR-TKIs; however, their impact on EGFR-TKI therapy outcomes in EGFR-mutant NSCLC has not yet been systematically evaluated. Methods: Patients with advanced NSCLC were prospectively registered from more than 35 institutes (HER2-CS STUDY UMIN 000017003). EGFR mutations or anaplastic lymphoma kinase gene translocations were assessed at each institution using a commercially approved test. HER2 protein expression levels were determined by immunohistochemistry (IHC) using the Ventana I-VIEW PATHWAY anti-HER-2/neu (4B5). The IHC status scoring system applied to gastric cancer was used. Results: Of 1,126 screened patients with NSCLC, 354 (31.8%) had EGFR-mutated tumors, and the HER2 protein statuses were as follows: IHC0 (n = 71, 26%), IHC1+ (n = 148, 53%), IHC2+ (n = 51, 18%), and IHC3+ (n = 7, 3%). The patients’ demographics were almost identical in those with lung tumors harboring EGFR mutations and HER2-IHC2+/3+ (group P) or EGFR mutations and HER2-IHC0/1 (group N). The EGFR-TKI response rates were not different between these groups (Table). However, group P showed significantly shorter time to EGFR-TKI treatment failure than group N (median 19.1 vs. 13.3 months; log rank p = 0.038). Conclusions: These data from a large prospective cohort show that HER2 protein expression in EGFR-mutant NSCLC may have a negative impact on the effect of EGFR-TKIs. A clinical trial of EGFR/HER2-TKIs (e.g., afatinib) is warranted for this population. [Table: see text]

scholarly journals Genetic diagnostic features after failure of initial treatment with epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors among non-small-cell lung cancer patients harboring EGFR mutations

2020 ◽  
Author(s):  
Yuichiro Takeda ◽  
Go Naka ◽  
Yoh Yamaguchi ◽  
Masao Hashimoto ◽  
Manabu Suzuki ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cancer Patients ◽  
Liquid Biopsy ◽  
Growth Factor Receptor ◽  
Egfr Mutations ◽  
First Line ◽  
Lung Cancer Patients ◽  
Epidermal Growth ◽  
Egfr Tki ◽  
Egfr Tkis

Abstract Background: Osimertinib, a third - generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI), can be used as a second-line treatment for lung cancer patients harboring the T790M substitution. Although osimertinib is more effective than the first-generation EGFR-TKIs used for first-line treatment, its efficacy with respect to long-term patient survival remains unclear even upon the administration of a complete sequence of EGFR-TKI therapy, and limited information is available regarding genetic diagnostic approaches after EGFR-TKI naïve treatment. This study investigated the characteristics of EGFR-mutated lung cancer patients harboring the T790M substitution resistance to EGFR-TKIs and the advantages of rebiopsy and liquid biopsy for these patients. Methods: The medical records of patients screened for EGFR mutations were reviewed. Upon failure of naïve treatment with EGFR-TKIs, except for osimertinib, single plexus cobas version 2 was repeatedly used to detect the T790M substitution in EGFR via tissue or liquid biopsy. Results: From April 2016 through May 2019, 113 patients were determined to harbor EGFR mutations. Sixty patients were treated with EGFR-TKIs, among which 46 underwent tissue or liquid biopsy. Twenty-nine of these 46 (63%) patients harbored the T790M substitution. In total, 141 rebiopsies were performed. The T790M substitution was detected in 24 of 43 tissue and 11 of 98 liquid biopsies. If patients displayed an EGFR exon 19 deletion, had new lesions, and were administered gefitinib as first-line therapy, patients harboring an EGFR mutation were suspected of harboring the T790M substitution. Furthermore, the T790M substitution was detected through rebiopsy in patients with co-existing original mutations, brain metastases, tumor enlargement by ≥ 12 mm, or metastases at minor sites. Conclusion: Repeated biopsy can help maximize the detection rate of the T790M substitution. Furthermore, the advantages of repeated tissue or liquid biopsy should be considered among patients with positive T790M factors , and these biopsies can be repeated numerous times .

scholarly journals Genetic diagnostic features after failure of initial treatment with epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors among non-small-cell lung cancer patients harboring EGFR mutations

2020 ◽  
Author(s):  
Yuichiro Takeda ◽  
Go Naka ◽  
Yoh Yamaguchi ◽  
Masao Hashimoto ◽  
Manabu Suzuki ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cancer Patients ◽  
Liquid Biopsy ◽  
Growth Factor Receptor ◽  
Egfr Mutations ◽  
Liquid Biopsies ◽  
Lung Cancer Patients ◽  
Epidermal Growth ◽  
Egfr Tki ◽  
Egfr Tkis

Abstract Background: Osimertinib, a third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI), can be used as second-line treatment for lung cancer patients harboring the T790M substitution. Although osimertinib is more effective than the first-generation EGFR-TKIs used for first-line treatment, its efficacy with respect to long-term patient survival remains unclear even upon the administration of a complete sequence of EGFR-TKI therapy. Moreover, limited information is available regarding genetic diagnostic approaches after the treatment of EGFR-TKI–naïve patients. This study investigated the clinical characteristics of EGFR -mutated lung cancer patients harboring the T790M substitution resistant to EGFR-TKIs, as well as the advantages of rebiopsy and liquid biopsy for these patients. Methods: The medical records of patients screened for EGFR mutations were reviewed. Upon failure of naïve treatment with EGFR-TKIs, except for osimertinib, single-plexus cobas version 2 was repeatedly used to detect the T790M substitution in EGFR via tissue or liquid biopsy. Results: From April 2016 through May 2019, 113 patients were found to harbor EGFR mutations. Sixty patients were treated with EGFR-TKIs, among whom 46 underwent tissue or liquid biopsy. Twenty-nine of these 46 (63%) patients harbored the T790M substitution. In total, 141 rebiopsies were performed. The T790M substitution was detected in 24 of 43 tissue biopsies and 11 of 98 liquid biopsies. If patients displayed an EGFR exon 19 deletion, had a new lesion, and were administered gefitinib as first-line therapy, they were suspected to harbor the T790M substitution. Furthermore, the T790M substitution was detected through rebiopsy in patients with coexisting original mutations, brain metastases, tumor enlargement by ≥ 12 mm, or metastases at minor sites. Conclusion: Among patients with positive factors associated with the T790M mutation, repeated tissue or liquid biopsies are useful to maximize the detection rate of the T790M substitution. Furthermore, these biopsies need to be repeated numerous times in order to reduce “detection overlook” among such patients.

scholarly journals DDIS-17. DEVELOPMENT OF BRAIN-PENETRANT EGFR INHIBITORS FOR CNS MALIGNANCIES

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi66-vi66
Author(s):  
Jonathan Tsang ◽  
Lorenz Urner ◽  
Christopher Tse ◽  
Lynn Baufeld ◽  
Kym Faull ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Tumor Response ◽  
Growth Factor Receptor ◽  
Structure Activity ◽  
Superior Efficacy ◽  
Egfr Tyrosine Kinase Inhibitors ◽  
Epidermal Growth ◽  
Egfr Tki ◽  
Egfr Tkis ◽  
Cns Malignancies

Abstract The epidermal growth factor receptor (EGFR) is altered in nearly 60% of glioblastoma (GBM) tumors, however, EGFR tyrosine kinase inhibitors (TKIs) have failed to improve outcomes for patients with GBM. This can be attributed to the inability of clinically available EGFR TKIs (e.g., erlotinib, gefitinib, lapatinib, afatinib, cetuximab) to effectively cross the blood-brain-barrier (BBB) and reach adequate pharmacological levels for a tumor response. Herein, we performed a structure-activity relationship (SAR) to obtain EGFR TKIs with both high brain penetrance and potency against EGFR-activated GBM cells. From over 80 novel compounds synthesized, our lead EGFR TKI—JCN068—exhibited exceptional BBB penetration (350% brain to plasma) while also having optimal ADME properties (60% oral bioavailability, ~5 hr half-life, >100 µg/mL solubility, etc). Moreover, JCN068 demonstrated picomolar potency against purified EGFR kinase, 1000-fold selectivity for EGFR relative to other kinases, and nanomolar activity against EGFR-altered, GBM patient-derived cells in culture. Importantly, JCN068 demonstrated superior efficacy—with negligible toxicity—compared to clinically available small molecule EGFR TKIs (erlotinib and lapatinib) against multiple EGFR-altered patient-derived orthotopic GBM xenografts. Due to these excellent drug-like properties, JCN068 is currently progressing towards clinical development for EGFR-activated GBM patients.

Rebiopsy of patients (pts) with acquired resistance to epidermal growth factor tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer (NSCLC)

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 8025-8025 ◽  
Author(s):  
M. E. Arcila ◽  
G. J. Riely ◽  
M. F. Zakowski ◽  
M. G. Kris ◽  
M. Ladanyi ◽  
...  
Keyword(s):  
Median Time ◽  
Progressive Disease ◽  
Kinase Inhibitors ◽  
Egfr Mutation ◽  
Acquired Resistance ◽  
Egfr Mutations ◽  
Met Amplification ◽  
Metastatic Sites ◽  
Egfr Tki ◽  
Egfr Tkis

8025 Background: The EGFR-TKIs erlotinib and gefitinib produce dramatic regressions of tumor in ∼ 70% of NSCLC patients with activating mutations in the EGFR-TK domain. After a median time to progression of ∼1 year, most pts have progressive disease. We undertook this study to search for mechanisms of “acquired resistance” to EGFR-TKIs, to determine the spectrum and frequency of secondary EGFR mutations which arose, and to determine the feasibility of rebiopsy in this setting. Methods: All pts had metastatic or recurrent NSCLC and prior treatment with EGFR-TKI and progressive disease while on EGFR-TKI. Pts must also have had an activating EGFR mutation OR radiographic response (RECIST or WHO) to EGFR-TKI OR significant and durable improvement in cancer-related symptoms as judged by patient's physician. Core biopsies were performed and studied for EGFR mutation (exons 18–21 including PCR-based test for T790M) and MET amplification. Results: From 8/04–12/08 98 pts were consented for rebiopsy and 85 underwent the procedure. Demographics Female/Male=59/39; median age 62 (range 28–88); smoking: never=59, former/current=39. Primary EGFR mutation was exon 19 del-39; exon 21 L858R-11, other/WT-28, pending-7. Median time on EGFR-TKI before biopsy was 12 months (7–28 months). Secondary EGFR mutations: T790M-33, other-2, none detected-31, indeterminate-10, pending-9. MET amplification in 2/16 studied to date. Conclusions: 1) Rebiopsy of patients with NSCLC and acquired resistance to EGFR TKIs is feasible and well-received by pts. 2) Knowledge of EGFR genotype including EGFR T790M and MET status can inform clinical trials of targeted therapies in this population 3) More complete annotation of MET status and exploratory analyses of profiles of specimens by metastatic sites and prior EGFR-TKI versus chemo and EGFR-TKI is ongoing. Supported by the Doris Duke Foundation, the LaBrecque Foundation, Steps for Breath, NIH, and an anonymous donor. No significant financial relationships to disclose.

Identification of RET fusion as mechanisms of resistance to EGFR tyrosine-kinase inhibitors.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e21074-e21074
Author(s):  
Zhongxing Bing ◽  
Weiran Wang ◽  
Danhua Wang ◽  
Tonghui Ma
Keyword(s):  
Lung Cancer ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Kinase Inhibitors ◽  
Next Generation Sequencing Data ◽  
Egfr Mutations ◽  
Egfr Tyrosine Kinase ◽  
Egfr Tyrosine Kinase Inhibitors ◽  
Egfr Tki ◽  
Egfr Tkis

e21074 Background: Responses to EGFR-targeted therapy are generally temporary, due to inevitable drug resistance. Although RET fusions have been identified in resistant EGFR-mutant non–small cell lung cancer (NSCLC), their characteristics acquired resistance to EGFR tyrosine-kinase inhibitors (TKIs) are rarely investigated. Methods: We retrospectively reviewed next-generation sequencing data of EGFR+ lung cancer patients, and 8 patients were identified coexisting of EGFR mutations and RET fusion. Their treatment history was collected. Results: The co-occurrence of RET fusion with EGFR oncogenic variations was observed in eight patients, and all of the 8 patients have received previous EGFR-TKI treatment. EGFR mutations were including 4 L858R mutations, 4 exon 19 deletions, and 6 T790M mutations. And the partner genes of RET identified by NGS were including TRIM33 (2/8), GPRC6A (1/8), TLN1 (1/8), KIAA1598 (1/8), SPECC1 (1/8), TRIM24 (1/8) and CCDC6 (1/8). The allelic fractions (AFs) of first-generation EGFR-TKI sensitizing mutations were higher than AFs of EGFR T790M mutations as well as AFs of RET fusion. These RET fusions are fused with rare partner genes, rather than the most common KIF5B in lung cancer. Conclusions: This study extended the knowledge of RET fusion as resistance mechanism to EGFR TKIs in lung cancer. The detection of RET fusions may uncover potential resistance mechanisms of EGFR TKIs, which might inform therapeutic strategies, such as combination-therapy approaches.[Table: see text]

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