대한내과학회지 : 제 93 권제 3 호 2018 https://doi.org/10.3904/kjm.2018.93.3.266 Roadmap to diagnosis 분자생물학적기법에근거한비편평상피세포폐암의진단과치료 고려대학교의과대학구로병원호흡기내과 이승룡 Diagnosis and Treatment of Non-Squamous Lung Cancer Based on Molecular Tumor Testing Sung Yong Lee Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea 증례 80세여자가 2주동안지속되는기침, 가래와우하엽폐침윤소견으로방문하였다. 특별한과거력은없었고흡연력도없었다. 2주간항생제치료를하였지만우하엽폐침윤소견은호전이없어흉부 computed tomography (CT) 를촬영하고우하엽폐침윤소견이외에양쪽폐에다발성결절소견관찰되어경피적폐생검을시행하였다 (Fig. 1). 조직검사상폐선암으로진단되었으며폐, 늑막전이소견관찰되어 4기로진단되었다. 1차치료약제의선택비흡연진행성폐선암환자로적합한항암치료약제를선별하기위해폐암조직에대해유전자검사를시행하였다. 상피세포성장인자수용체 (epidermal growth factor receptor, EGFR) 유전자변이유무를확인하기위해 peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping 방법을이용하여검사를진행하였다. Exon 19번에 deletion mutation이확인되었다. 이유전자변이를표적으로하는 EGFR tyrosine kinase inhibitor (EGFR TKI) 약제인 afatinib을투여하였으며 2개월후시행한반응평가흉부 CT에서부분관해 (partial response, PR) 의항암효과를관찰할수있었다. 2개월간격으로반응평가 CT 촬영하면서약제투여를하였고 10 개월후반응평가흉부 CT에서종양의크기가 20% 이상증가하는질병진행 (progressive disease, PD) 소견이관찰되었다. 2차치료약제의선택 1세대또는 2세대 EGFR TKI 약제투여후평균 9-12개월에서 50% 의환자들이 EGFR TKI 의약제내성으로종양의크기가다시성장하기시작한다 [1]. 약제의내성기전을확인하고 2차치료약제를선택하기위해다시폐생검을시행하였다. 다시얻은폐암조직에서동일한폐선암으로진단되었으며폐암조직에대해유전자변이검사를실시하였다. 유전자변이검사상기존의 exon 19 Del 유전자변이와 exon 20 T790M 유전자변이가관찰되었다. 환자는 T790M 유전자변이를표적으로하는 osimertinib 약제를새롭게처방받았으며반응평가 CT상다시부분관해 (PR) 의반응률을보이고 Correspondence to Sung Yong Lee, M.D., Ph.D. Department of Internal Medicine, Korea University Guro Hospital, 148 Gurodong-gil, Guro-gu, Seoul 08308, Korea Tel: +82-2-2626-3030, Fax: +82-2-2626-1166, E-mail: Syl0801@korea.ac.kr Copyright c 2018 The Korean Association of Internal Medicine This is an Open Access article distributed under the terms of the Creative Commons Attribution - 266 - Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
- Sung Yong Lee. Molecular diagnosis and treatment of non-squamous lung cancer - A B Figure 1. (A) Chest X-ray and (B) computed tomography scans. A 5.3-cm mass in the superior segment of the right lower lung, encasing right lower lobar and segmental bronchi. 특별한부작용은없는상태이다. 고찰 2000년도초상피세포성장인자수용체억제제 (gefitinib, erlotinib) 의등장이후로진행성비소세포폐암환자들의평균생존율 (median overall survival) 은 2000년도초 8-10개월의생존율에서최근에는 2-3년까지평균생존율이늘어나게되었다 [2]. 그러나모든폐암환자들에서생존율의향상이온것이아니고특정유전자변이나단백질발현이있는환자에서그러한것들을표적으로하는약제를사용할때좋은성적을보였으며오히려그러한표적이없는환자에서그러한표적치료제를사용하게되면부작용발생의증가뿐만아니라생존율이더떨어지는역효과를보였다. 과거표적치료제가개발된당시에는표적치료라는치료개념이나왔다가최근에는그러한표적치료를적합한환자들에게치료하는정밀의학 (precision medicine) 이라는각각의환자에게적합한맞춤치료라는개념이도입되었다. Precision medicine ( 정밀의학 ) 정밀의학이란각환자의유전정보, 질병정보, 생활습관등개인의의학정보를근거로각각환자에게최적화된진단 과치료를제공하는의학을말한다. 즉, 환자개인의의학관련정보들을정밀하게분석, 분류하여효과적인치료방법을선택하게끔하는의학이다. 2015년 1월버락오바마미국대통령이정밀의료계획 (precision medicine initiative) 을발표하고나서더우리들에게친숙한단어로다가온개념이다. 정밀의학의개념을도입하고가장그개념을잘이용하고있는치료분야가비소세포폐암분야이며그대표적인대상이되는약제가상피세포성장인자수용체억제제이다. 2000년대초 gefitinib이라는약제가처음폐암환자들에게사용되고일부환자에게획기적인반응을보였을때 (IDEAL 1 [3], IDEAL 2 [4] Trials) 폐암치료에서낙관하는분위기였으나 ISEL Trial (A Phase III survival study comparing gefitinib (IRESSA) plus best supportive care (BSC) with placebo plus BSC, in patients with advanced non-small cell lung cancer (NSCLC) who had received one or two prior chemotherapy regimens) 3상임상연구를통해 gefitinib이 best supportive care 와비교하였을때생존율의향상을입증하지못하고미국의약시장에서퇴출되었다 [5]. 당시에는 gefitinib 약제가상피세포성장인자수용체를억제하지만정확한기전을모르는상태에서환자의선별없이환자들을등록하여임상연구를진행하여의미있는결과를얻지못하였지만동양인, 여성, 비흡연자에서반응이좋았다는결론만내릴수있었다. 그이후 - 267 -
- 대한내과학회지 : 제 93 권제 3 호통권제 682 호 2018 - gefitinib 약제반응이좋은환자들의조직샘플을이용한유전자검사를통해 2004년 NEJM [6] 과 Science [7] 지에상피세포성장인자수용체의유전자변이가있는경우 gefitinib의약제반응이좋다는보고가되었다. 그이후 EGFR TKI 약제가 EGFR의 intracellular domain 에약제 binding site에유전자변이가있는경우약제반응이좋다는사실이알려지고나서그러한개념을이용하여시행한임상연구에최초로의미있는결과를보고한것이 gefitinib or carboplatin-paclitaxel in pulmonary adenocarcinoma (IPASS trial) 이다 [8]. 이임상연구를통해서특정유전자를표적으로하는표적치료임상에서특정유전자변이를갖은환자들만을대상으로하는임상연구들이진행이되었으며그러한임상연구결과들을통해폐선암으로진단된환자에서는 EGFR mutation test가필수적으로시행해야하는검사항목이되었으며그러한검사에서유전자변이가확인된환자들은 EGFR TKI 약제를투여받게되었다. 즉, EGFR 을표적으로하는 EGFR TKI 약제가개발되었으며약제의반응이 EGFR의유전자변이에따라달라 진다는사실에근거하여 EGFR mutation 이있는환자들을대상으로 EGFR TKI 약제를투여한결과기존세포독성항암치료에서는얻을수없는생존율의향상을얻게되어이러한일련의과정이 precision medicine의개념을이용하여실제폐암환자를치료하게된좋은예이다. 유전자변이검사방법진행성비편평상피세포폐암환자는진단과동시에적합한항암제선택을위해폐암조직또는세포진검사에서암세포를추출해서유전자검사를시행한다. EGFR mutation 발생비율이 anaplastic lymphoma kinase (ALK) translocation의발생비율보다높기때문에 (Fig. 2) EGFR mutation test를먼저하고음성인경우 ALK translocation FISH test를그이후시행하기도하지만최근 ALK 억제제가 1차치료약제로보험급여로인정받고나서는빠른진단을위해 EGFR mutation test와 ALK translocation FISH test 를동시에진행하기도한다 [1]. EGFR mutation test와 ALK test 에서모두음성을보인경우최근빈도는낮지만 ROS-1 유전자변이검사를시행하기도한다 (Table 1). EGFR mutation test는과거 direct gene sequencing method를 Table 1. Anticancer drugs and their pharmacogenomic biomarkers Figure 2. The proportion of lung adenocarcinoma harboring aberrations in driver oncogenes. RET, rearranged during transfection; ALK, anaplastic lymphoma kinase; KRAS, kirsten rat sarcoma; EGFR, epidermal growth factor receptor. Biomarker with pharmacodynamic effect EGFR ALK ROS-1 BRAF Associated drug Gefitinib, erlotinib, afatinib, osimertinib Crizotinib, ceritinib, alectinib Crizotinib Dabrafenib, trametinib EGFR, epidermal growth factor receptor; ALK, anaplastic lymphoma kinase. Table 2. Sensitivity of EGFR-mutation-based techniques Technique Sensitivity (% of mutant DNA) Mutation identified Potential application Direct sequencing 10-25 Known and new Tissue Pyrosequencing 5-10 Known only Tissue Cobas 3-5 Known only Tissue Next-generation sequencing 1-10 Known and new Tissue, plasma PNA clamping PCR 1-0.1 Known only Tissue, plasma Beads, emulsification, amplification, and magnetics < 0.1 Known only Tissue, plasma Digital droplet PCR < 0.1 Known only Tissue, plasma EGFR, epidermal growth factor receptor; PNA, peptide nucleic acid; PCR, polymerase chain reaction. - 268 -
- 이승룡. 분자생물학적기법에근거한폐암의진단과치료 - 이용하여유무를확인하였다. Uncommon mutation을검출할수있다는장점이있으나 sensitivity가낮고염기서열분석을위한기계가있어야하는단점들이있어최근에는알려져있는특정유전자변이들에대한 primer 를이용한 PNA clamping PCR method 를이용한검사가국내에서보편적으로사용되고있다 (Table 2). 그리고국내에서도 2017년 3월보건복지부고시를통해차세대염기서열분석 (next generation sequencing, NGS) 기반유저자패널검사에대한행위료를신설해암유전체검사에대해보험급여를적용하여현재암환자를대상으로수백가지에이르는암유전자를스크리닝하는암유전체검사를시행하고있으며, 유전체검사결과에따라유전자변이에적합한치료약제가있는경우그러한약제를투여할수있다 [9]. 또한최근조직검사를통한유전자검사의경우조직검사도중발생할수있는합병증으로쉽게조직을얻지못하는경우혈액내의 cell free DNA 를추출및증폭하여유전자변이유무를검사하는액상생검 (liquid biopsy) 을할수있는 kit가상용화되어폐암환자들에서 EGFR mutation 유무를혈액샘플을통해확인하고 EGFR TKI 약제를투여할수있게되었다 [10]. 혈액이나소변과같은타액에서암세포유래유전자를분리하고분석하는기술이발달함에따라실제조직에서시행한유전자검사결과의 60-70% 의민감도를갖고있으며이러한액상생검을통한유전자변이검사결과를토대로 EGFR TKI 약제의반응률이조직에서와거의유사한결과를보고하고있다 [11]. 최근액상생검에서 NGS를이용하면 EGFR, ALK, ROS-1 유전자변이유무를확인동시에확인해서표적이되는치료약제를바로선택하려는시도들이진행되고있으며, 그러한임상자료들이점차축적이된다면향후암조직생검없이액상생검을통해유전자변이유무결과를확인하고그러한유전자변이결과를토대로적절한표적치료제로치료할수있을것으로기대된다. 요약최근폐암은정밀의학에근거한분자병리학적분류및치료기법이도입되면서생존율이과거에비해 2-3배정도증가하였다. 폐암은동일한하나의질환이아니라다양한조직학적, 유전자변이및암단백발현을하고있는환자들로구성되어있으며그래서가능한동질성의환자군들로분류하고각분류된환자들에게적합한약제를투여하는과정이필 요하다. 과거에비해좀더세분화된병리학적진단과유전자변이유무를확인하는것이필요불가분의조건이되었으며그러한진단을위해더많은조직획득이필요하게되었으며그러한조직획득이어려운경우를극복하기위해액상생검을이용한진단기법들이발전하고있다. 현재 EGFR, ALK, ROS-1 유전자변이가있는경우그러한유전자를표적으로하는약제들을사용할수있으며, 점차표적이되는유전자및약제개발이증가되어진행성폐암환자들의생존율이더욱증가할것으로기대된다. 중심단어 : 분자생물학적진단 ; 비편평상피폐암 ; 상피세포성장인자수용체 REFERENCES 1. Hong Y, Kim WJ, Bang CY, Lee JC, Oh YM. Identification of alternative splicing and fusion transcripts in non-small cell lung cancer by RNA sequencing. Tuberc Respir Dis (Seoul) 2016;79:85-90. 2. Yang JC, Wu YL, Schuler M, et al. Afatinib versus cisplatin-based chemotherapy for EGFR mutation-positive lung adenocarcinoma (LUX-Lung 3 and LUX-Lung 6): analysis of overall survival data from two randomised, phase 3 trials. Lancet Oncol 2015;16:141-151. 3. Fukuoka M, Yano S, Giaccone G, et al. Multi-institutional randomized phase II trial of gefitinib for previously treated patients with advanced non-small-cell lung cancer (The IDEAL 1 Trial) [corrected]. J Clin Oncol 2003;21:2237-2246. 4. Kris MG, Natale RB, Herbst RS, et al. Efficacy of gefitinib, an inhibitor of the epidermal growth factor receptor tyrosine kinase, in symptomatic patients with non-small cell lung cancer: a randomized trial. JAMA 2003;290:2149-2158. 5. Thatcher N, Chang A, Parikh P, et al. Gefitinib plus best supportive care in previously treated patients with refractory advanced non-small-cell lung cancer: results from a randomised, placebo-controlled, multicentre study (Iressa Survival Evaluation in Lung Cancer). Lancet 2005;366: 1527-1537. 6. Lynch TJ, Bell DW, Sordella R, et al. Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib. N Engl J Med 2004;350:2129-2139. 7. Paez JG, Jänne PA, Lee JC, et al. EGFR mutations in lung cancer: correlation with clinical response to gefitinib therapy. Science 2004;304:1497-1500. - 269 -
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