Efficacy of EGFR-TKl sequential therapy in patients with EGFR exon 19 insertion-

lNTRODUCTlON

The epidermal growth factor receptor(EGFR),a kind of receptor tyrosine kinase,plays critical roles in the initiation,promotion,and progression of malignant tumors by modulating downstream signaling pathways[1].It has been documented thatis overexpressed and mutated in several tumors,including non-small cell lung cancer(NSCLC)[2].Apparently,serves as an important regulator of lung cancer growth,and overexpression ofsymbolizes the advancement of lung cancer,which is correlated with poor prognosis[3].These characteristics suggestas a promising molecular target for tumor-specific therapy.mutations occur primarily in the EGFR tyrosine kinase(EGFR-TK)coding region,the target of EGFR tyrosine kinase inhibitors(TKIs)[4].In NSCLC,especially lung adenocarcinoma,mutation is an important indicator for the use of EGFR TKIs.Therefore,the detection ofmutation can facilitate the optimal use of these TKIs.The United States Food and Drug Administration has successively approved several EGFR TKIs as standard treatment regimens for NSCLC in first-line treatment.Differentmutants showed different sensitivity to EGFR TKIs.

The most commonmutations are short,in-frame deletions in exon 19(usually 15 or 18 base pairs)and the exon 21 point mutation L858R and sensitive to the EGFR TKIs[5].Othermutations are rare and respond differently to EGFR TKIs.Among these,exon 20 insertion mutation and T790M mutation are related to drug resistance.G719X,E709K,S768I are reported as moderate sensitive mutations[6].Theexon19 insertion mutation is also rare and accounts for only 0.11% of all lung cancer patients and 0.23% ofmutation patients in the East Asian population[7].Studies and case reports have shown that first-generation EGFR TKIs are effective in lung adenocarcinoma patients withexon 19 insertion.In contrast,second-generation afatinib has limited reports concerning this mutation[8].

Herein,we presented a NSCLC case carrying the rareexon 19 insertion mutation.The patient had a good and durable response to afatinib,which provides clinical evidence for the use of afatinib in these patients.

CASE PRESENTATlON

Chief complaints

In this study,a 63-year-old Chinese male(45 pack year history)presented with chest pain for several days.

History of present illness

Patients a had history of chest pain.

History of past illness

We acknowledge the contributions to this study from the patient and his family,the pathology department,and the radiology department.

Personal and family history

Patient had a long history of heavy smoking.

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Physical examination

One month later,the patient underwent right lower lobectomy,right upper lobe wedge resection,and mediastinal lymphadenectomy under general anesthesia.Postoperative pathology suggested that patient had a T4N2M0(stage IIIB)right lung adenocarcinoma with a positive surgical margin.

Laboratory examinations

Shan BB,Zhang QM,and Li Y conceived and designed the study;Zhao C analyzed the data;An XQ contributed to literature review;Zhang QM wrote the manuscript and reviewed and edited the manuscript;Shan BB and Li Y contributed equally to this study;all authors read and approved the final manuscript.

Imaging examinations

Chest computed tomography(CT)revealed a ground-glass nodule in the right upper lobe(about 2 cm ×1.5 cm),a nodular soft tissue density(about 2.02 cm × 2.7 cm)in the right lower lobe,and the presence of multiple lymph nodes in mediastinal space(Figure 1).

FlNAL DlAGNOSlS

After 1 mo,the patient received Gefitinib,a first-generation EGFR-TKI at a dose rate of 250 mg per day.Four months later,the patient visited again with chest and back pain.The patient underwent preoperative examination,and results showed no distant metastasis,as diagnosed by magnetic resonance imaging,abdominal ultrasound,and full-body bone scan.However,chest CT showed a postoperative change in the right lung.Meanwhile,bone scan showed multiple metastasis bone lesions of the sternum and the left seventh rib(Figure 1).The patient presented with recurrent postoperative metastasis with disease-free survival of 4 mo.

TREATMENT

Since the diagnosis of the recurrent metastasis,afatinib 30 mg p.o.daily was started to achieve the symptomatic control of the chest pain.After 8 mo,patient showed slow progression of the right upper lobe lesion(Figure 1).Due to the elevated tumor marker,carcinoembryonic antigen,a second NGSbased genetic testing of 73 cancer-related genes was performed on the patient’s peripheral blood sample(Geneplus-Beijing Ltd.,Beijing,China)to identify possible causes and potentially targeted mutations.The test revealed a somaticexon 19 insertion(NM_005228.3,c.2214_2231dupTAAAATT CCCGTCGCTAT,p.I740_K745dup)(Figure 2),which was identical to the mutation previously detected in the lung cancer samples.The NGS results suggest that afatinib was the best treatment to follow.Therefore,the patient continued to receive oral afatinib for 5 mo.Adverse reactions,such as skin rashes,nausea,vomiting,and diarrhea,were noted during the afatinib treatment course,which were treated symptomatically.Meanwhile,the patient reported the onset of acute sharp chest pain.Chest CT showed multiple bands in both lungs and a right pleural effusion(Figure 1).It is noteworthy that,initially,pleural effusion was slowly elevated without distinct clinical symptoms and pleural effusion puncture and drainage.After that,pleural effusion of the patient was augmented with chest depression,shortness of breath,and poor fluid quality,which was manifested as clinical progress.Later,the patient presented with dyspnea and cachexia,indicating clinical progression.The progression-free survival for the patient treated with afatinib was 13.4 mo.The patient,with no clinical improvement,was then switched to oral Osimertinib treatment,a third-generation EGFR-TKI.The three generations of drugs were taken orally instead of pleural effusion puncture and drainage.

OUTCOME AND FOLLOW-UP

The patient passed away after receiving 2 mo of treatment,with overall survival length of 21.3 mo.

The authors declare that they have no conflict of interest.

DlSCUSSlON

Written informed consent was obtained from the patient for publication of the clinical data and any accompanying images.This is a retrospective case report and institutional approval was not needed.

In the course of treatment,the surgical and peripheral blood samples were sent for second-generation sequencing to evaluate the mutations in 73 genes.The sequencing analysis to determine the mutations,including point mutations,small fragment insertions and/or deletions,copy number variations,and known fusion gene variations,are related to tumor occurrence and development.The results showed insertion mutation in exon 19 of EFGR gene.The nucleotide mutation was p.i740 K745dup,which results in the insertion of certain amino acids in the protein encoded by the EGFR gene.Previously,this mutation was not recorded in Catalogue of Somatic Mutations in Cancer and Memorial Sloan Kettering databases[11].All patients withexon 19 insertion had amino acid change causing substitution of leucine at residue 747 by proline(L747P).The amino acid sequences ofexon19 insertions reported in the literature include I740_P741insPVAIKI,I740_K745insIPVAIK,I744_K745insKIPVAI,K745_E746insIPVAIK,K745_E746insVPVAIK,and K745_E746insTPVAIK.Among these,the first four forms of mutation cause the same changes in the amino acid sequence.This amino acid change finally activates the tyrosine phosphorylation by binding with ligands.Autophosphorylation promotes downstream signal transduction pathways,including mitogen-activated protein kinase,phosphatidylinositol 3 kinase,and jun N-terminal kinase pathways,which induce cell proliferation and differentiation[12].

The patient reported in the current report had lesions in both right upper and lower lobes,as demonstrated on preoperative chest CT images,and there were ground-glass nodules in both lung lobes.The postoperative pathology of both nodules was adenocarcinoma.Mediastinal lymph nodes were positive.It is unclear whether they are both primary foci or one of them metastasized from the other.The earliest diagnostic criteria for multiple primary lung cancer(MPLC)was reported by Martini[13],which focused on different tissue types.With the development of molecular pathology,the American Association of Chest Physicians revised the diagnostic criteria of MPLC.The new criteria classified the simultaneous multiple cancers located in different lobes without N2 and N3 lymph node infiltration and without systemic metastasis as MPLC.It also added molecular genetic characteristics.The histological subtype of lung adenocarcinoma is recommended to distinguish MPLC from lung metastasis[14].There is literature showing that second-generation sequencing can be used to increase the diagnostic accuracy.There is a general consensus among several countries on the treatment of MPLC.However,the surgical treatment is considered as the first choice.Stella[15]suggested that surgical treatment should be performed no matter whether the multiple lesions are MPLC or pulmonary metastasis,as long as the lung function is acceptable and there is no lymph node metastasis.

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CONCLUSlON

This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers.It is distributed in accordance with the Creative Commons Attribution NonCommercial(CC BYNC 4.0)license,which permits others to distribute,remix,adapt,build upon this work non-commercially,and license their derivative works on different terms,provided the original work is properly cited and the use is noncommercial.See:https://creativecommons.org/Licenses/by-nc/4.0/

ACKNOWLEDGEMENTS

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FOOTNOTES

Next-generation sequencing(NGS)was performed to identify the targeted mutations and identified anexon 19 insertion mutation.

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The insertion mutation in exon 19 ingene is usually sensitive to targeted therapy[9].Most patients with this mutation are females with adenocarcinoma who are non-smokers or light smokers.In patients with advanced NSCLC,first-generation EGFR TKIs are often used as the postoperative adjuvant or firstline treatment.The efficacy of TKIs fluctuates from 15.5%-24%[8].A limited number of studies used the second-generation EGFR TKI,which achieved the best clinical results[9].The case that we presented in this study is a male patient with a history of heavy smoking,who was treated with sequential EGFRTKIs treatment.However,the efficacy of the first generation of TKI was only 30% and achieved 4 mo disease-free survival.The second-generation TKI afatinib treatment resulted in progression-free survival of 13.4 mo,which could be contributed to the fact that afatinib is a pan human epidermal growth factor receptor family inhibitor[9].The last sequential use of Osimertinib treatment lasted 2 mo,and the overall survival was 21.3 mo.So far,this is the first time that Osimertinib was used to treat patient carrying EGFR19 insertion mutation.There are reports that the incidence of rare mutation T790M is low after treatment with afatinib[10].

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“You must always remain with me,” said the emperor. “You shall sing only when it pleases you; and I will break the artificial bird into a thousand pieces.”

The authors have read the CARE Checklist(2016),and the manuscript was prepared and revised according to the CARE Checklist(2016).

In conclusion,we presented a case of lung adenocarcinoma with rareexon 19 insertion benefitting from afatinib therapy.This case provides unequivocal clinical evidence for the afatinib effectiveness in lung adenocarcinoma patients harboringexon 19 insertion and also provides evidence that these patients may benefit from EGFR TKIs sequential therapy.The treatment of this case is worth further discussing the importance of following the guidelines and initiating the standardized treatment.On the other hand,in the case of two nodules in different lobes,more molecular diagnosis is required to confirm the origin of the two nodules,which would be helpful for the selection of suitable drugs.

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China

Bin-Bin Shan 0000-0002-0968-7000;Yuan Li 0000-0001-5034-5419;Chang Zhao 0000-0003-0653-0742;Xiao-Qin An 0000-0001-5634-4601;Quan-Mao Zhang 0000-0003-0581-8349.

When the robber got home and found no dog he thought He must have gone back to his old master, and, though night had already fallen, he went off after him

Liu JH

20.Are you afraid?: Once she has made her decision, the heroine faces her betrothed66 and her future without fear. She is asked several times throughout the tale if she is afraid, but she never is. Return to place in story.#p#

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Liu JH