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Heterogeneity of epidermal growth factor receptor mutations within a mixed adenocarcinoma lung nodule
Lung Cancer (2008) 60, 136—140
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/lungcan
CASE REPORT
Heterogeneity of epidermal growth factor receptor mutations within a mixed adenocarcinoma lung nodule Hirofumi Nakano a, Hiroshi Soda a,b,∗, Mineyo Takasu c, Nanae Tomonaga a, Hiroyuki Yamaguchi a, Katsumi Nakatomi a, Satoru Fujino d, Tomayoshi Hayashi e, Yoichi Nakamura a, Kazuhiro Tsukamoto c, Shigeru Kohno a a
Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki 852-8501, Japan Division of Respiratory Medicine, Sasebo City General Hospital, Sasebo 857-8511, Japan c Department of Pharmacotherapeutics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8521, Japan d Internal Medicine, Saint Francisco Hospital, Nagasaki 852-8125, Japan e Department of Pathology, Nagasaki University Hospital, Nagasaki 852-8501, Japan b
Received 20 April 2007; received in revised form 14 August 2007; accepted 19 August 2007
KEYWORDS Lung cancer; Atypical adenomatous hyperplasia; Bronchioloalveolar carcinoma; Mixed adenocarcinoma; Epidermal growth factor receptor mutations; Gefitinib
Summary It has been proposed that stepwise progression occurs from atypical adenomatous hyperplasia (AAH) through bronchioloalveolar carcinoma (BAC) to invasive lung adenocarcinoma. However, the underlying molecular mechanisms have not been identified. We report a patient with a mixed adenocarcinoma of the lung that had different EGFR mutations in the papillary subtype, the acinar subtype, and the surrounding AAH and BAC areas. EGFR mutations may accumulate during tumor progression and lead to heterogeneity of EGFR mutations within the tumor. © 2007 Elsevier Ireland Ltd. All rights reserved.
1. Introduction ∗ Corresponding author at: Division of Respiratory Medicine, Sasebo City General Hospital, 9-3 Hirase, Sasebo 857-8511, Japan. Tel.: +81 956 24 1515; fax: +81 956 22 4641. E-mail address: [email protected] (H. Soda).
Lung adenocarcinoma with bronchioloalveolar carcinoma (BAC) features is frequently seen on thin-section chest computed tomography (CT) [1]. This type of adenocarcinoma is thought to develop from atypical adenomatous hyper-
0169-5002/$ — see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.lungcan.2007.08.021
Heterogeneity of epidermal growth factor receptor mutations within a mixed adenocarcinoma lung nodule
137
plasia (AAH) through BAC [1,2]. However, the molecular mechanism by which AAH and BAC evolve into invasive adenocarcinoma has not yet been determined. In BAC, mutations of the epidermal growth factor receptor (EGFR) gene are often observed [3—5]. Recently, two study groups have reported that transgenic mice bearing EGFR mutations develop BAC and lung adenocarcinoma [6,7]. Since EGFR mutations may be involved in the evolution of adenocarcinoma, it is important to know the EGFR mutation status in the various parts of a lung adenocarcinoma. We report a patient with different EGFR mutation patterns in the invasive adenocarcinoma and in the surrounding AAH and BAC areas.
2. Case report A 61-year-old, Japanese, female non-smoker was admitted for investigation of a nodule that was seen on chest radiography. A chest CT scan showed a 4-cm, solid nodule surrounded by ground-glass opacity (GGO) in the right upper lobe, along with enlargement of mediastinal lymph nodes (Fig. 1). A diagnosis of stage IIIA lung adenocarcinoma was made; the patient received combination chemotherapy followed by right upper lobectomy. Histological examination showed mixed adenocarcinoma with papillary and acinar subtypes and surrounding AAH and BAC areas (Fig. 2). On the CT scan, the AAH and BAC areas showed GGO, while the papillary and acinar subtypes formed the solid part of the nodule. Four months later, the patient developed mul-
Fig. 1 Transverse, thin-section, computed tomography scan shows a 4-cm, lobulated nodule consisting of a solid portion and ground-glass opacity with coarse spiculations in the right upper lung lobe.
tiple bilateral lung metastases. The patient was treated with several anti-cancer drugs. Two years after the recurrence was noted, the patient began taking gefitinib, an EGFR tyrosine kinase inhibitor. For 1 year, the pulmonary lesions improved remarkably, but then progressed. Gefitinib treatment was interrupted for 2 months, and then re-started. Though the lesions regressed for 1 month,
Fig. 2 Histological findings of the different areas of a resected lung nodule. (A) Atypical adenomatous hyperplasia, (B) bronchioloalveolar carcinoma, (C) papillary adenocarcinoma, and (D) acinar adenocarcinoma.
138
H. Nakano et al.
Fig. 3 Representation of the direct DNA sequencing for PCR products including hot-spot deletions in exon 19 of EGFR for each adenocarcinoma subtype. After electrophoresis on 6% acrylamide gel for PCR products, including heterozygous deletion in exon 19, DNA was extracted from shorter-sized PCR products that had a deletion, and was subsequently subjected to direct DNA sequencing. (A) Homozygous deletion in exon 19 in the papillary subtype; (B) heterozygous deletion in atypical adenomatous hyperplasia (AAH) and bronchioloalveolar carcinoma (BAC) subtype; and (C) no deletions in acinar, AAH, and BAC subtypes. Homozygous deletion ranged from E746 to A750 including 15 base-pair nucleotides (GGAATTAAGAGAAGC), compared with the no deletion sequence. In the AAH and BAC areas, the deletion involved in the heterozygous deletion was identical to that noted in the homozygous deletion in the papillary subtype (data not shown). Red vertical bars indicate deletion sites. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
they subsequently progressed, and the patient died despite treatment. The EGFR mutations were retrospectively analyzed using the microdissection technique for paraffin-embedded surgical specimens after obtaining the patient’s written informed consent. Four microdissected samples were obtained from the different parts of each histological subtype, and DNA extraction was performed using EXPATTM (Takara Bio Inc., Shiga, Japan); then, EGFR hot-spot mutation analysis was done. Deletion in exon 19 and the point mutations of both T790M in exon 20 and L858R in exon 21 were determined using the simple polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) methods, respectively. Our results indicate that there was only a deletion in exon 19; neither T790M nor L858R was affected. Deletions from E746 to A750 in exon 19 were confirmed by PCR-direct DNA sequencing analysis. The sequencing analysis indicated that the EGFR mutation status in each adenocarcinoma subtype was different (Table 1). The peripheral AAH and BAC areas showed either heterozygous deletion or no deletion in exon 19. In the central area of the nodule, the papillary subtype had both homozygous
and heterozygous deletions in exon 19, whereas the acinar subtype had no deletion (Fig. 3).
3. Discussion It has been proposed that a stepwise progression occurs from AAH through BAC to invasive adenocarcinoma [1,2]. In the current case, the peripheral AAH and BAC areas had a heterozygous deletion in exon 19, whereas the papillary subtype in the central areas of the nodule mainly had a homozygous deletion. There are two possible explanations for the heterozygosity found in the AAH and BAC areas: (1) the homozygous deletion was contaminated by wild-type DNA; or (2) it was a true heterozygous deletion. Several investigators have also reported that tumor cells in central areas exhibit more allelic losses than those in peripheral BAC areas [8,9]. EGFR mutations are less frequently observed in AAH and BAC areas, compared to areas of invasive adenocarcinoma [10]. A recent study has shown that, in gastrointestinal stromal tumors, the shift from heterozygous mutations in KIT exon 11 to homozygous mutations occurs during tumor
Heterogeneity of epidermal growth factor receptor mutations within a mixed adenocarcinoma lung nodule Table 1
139
EGFR mutations within a single tumor by histological subtype
Histological subtype (number of samples)
Homozygous deletion in exon 19
Heterozygous deletion in exon 19
No deletion
AAH areas (n = 4) BAC areas (n = 4) Papillary AD (n = 4) Acinar AD (n = 4)
0 0 3 0
2 2 1 0
2 2 0 4
AAH: atypical adenomatous hyperplasia, BAC: bronchioloalveolar carcinoma, AD: adenocarcinoma.
progression, and that the presence of homozygosity is associated with a worse disease course [11]. These findings support a hypothetical model of clonal evolution that starts with heterozygous deletion in exon 19 and progresses to homozygous deletion in papillary adenocarcinoma (Fig. 4). Furthermore, in the central areas, the papillary subtype had a deletion in exon 19, and acinar subtypes without EGFR mutations were observed; however, the peripheral AAH and BAC areas showed a mixture of deletions and no deletion in exon 19. These findings suggest that each subtype of lung adenocarcinoma develops through different carcinogenesis pathways, which leads to the heterogeneity of EGFR mutations in the tumor (Fig. 4). Since the patient received conventional chemotherapy pre-operatively, it is possible that conventional chemotherapy may have affected the status of the EGFR mutations. However, to the best of our knowledge, there are no reports that conventional chemotherapy induces additional mutations of EGFR. In addition, prior chemotherapy is not related to the effects of gefitinib [12]. Thus, neoadjuvant chemotherapy in the current case was unlikely to have affected the status of EGFR mutations.
In lung cancer patients, EGFR mutations are a predictor of clinical response to gefitinib. However, even though lung cancer patients with EGFR mutations are good responders, disease progression is inevitable and occurs within 1 year of therapy. Little is known about the mechanisms by which resistance to gefitinib develops in patients with EGFR mutations. Several investigators reported that the additional mutation of T790M is, at least in part, related to the acquisition of gefitinib resistance [13,14]. A recent case report showed different treatment responses to gefitinib in a patient with lung adenocarcinoma co-expressing a certain EGFR mutation in the primary lung tumor and a wildtype gene in metastatic bone lesions [15]. It is noteworthy that several lung cancer cell lines include cells without EGFR mutations and cells with certain EGFR mutations [16]. In the current report, based on the microdissection results, heterogeneity of EGFR mutations was also observed within the adenocarcinoma nodule. Heterogeneity of EGFR mutations within the tumor may be related to gefitinib response and resistance.
Conflict of interest None
References
Fig. 4 A hypothetical model of clonal evolution during the development of lung adenocarcinoma in the current case. There are two cell populations with either heterozygous deletion in exon 19 (shaded circle) or no deletion in exon 19 (open circle) in early neoplastic lesions such as atypical adenomatous hyperplasia (AAH) and bronchioloalveolar carcinoma (BAC). Acinar adenocarcinoma develops from the cell population with no deletion in exon 19, whereas papillary adenocarcinoma develops from cells with heterozygous deletion in exon 19. The shift from heterozygous deletion in exon 19 to homozygous deletion (closed circle) occurs during progression of papillary adenocarcinoma.
[1] Takeshima S, Maruyama Y, Hasegawa M, Yamanda T, Honda T, Kadoya M, et al. CT findings and progression of small peripheral lung neoplasms having a replacement growth pattern. Am J Roentgenol 2003;180:817—26. [2] Noguchi M, Morikawa A, Kawasaki M, Matsuno Y, Yamada T, Hirohashi S, et al. Small adenocarcinoma of the lung. Cancer 1995;75:2844—52. [3] Blons H, Cote JF, Le Corre D, Riquet M, Fabre-Guilevin E, Laurent-Puig P, et al. Epidermal growth factor receptor mutations in lung cancer are linked to bronchioloalveolar differentiation. Am J Surg Pathol 2006;30:1309—15. [4] Haneda H, Sasaki H, Shimizu S, Endo K, Suzuki E, Yukiue H, et al. Epidermal growth factor receptor gene mutation defines distinct subsets among small adenocarcinomas of the lung. Lung Cancer 2006;52:47—52. [5] Matsumoto S, Iwakawa R, Kohno T, Suzuki K, Matsuno Y, Yamamoto S, et al. Frequent EGFR mutations in noninvasive bronchioloalveolar carcinoma. Int J Cancer 2006;118:2498—504. [6] Politi K, Zakowski MF, Fan PD, Schonfeld EA, Pao W, Varmus HE. Lung adenocarcinomas induced in mice by mutant EGF receptors found in human lung cancers respond to a tyrosine kinase inhibitor or to down-regulation of the receptors. Genes Dev 2006;20:1496—510.
140 [7] Ji H, Li D, Chen L, Shimamura T, Kobayashi S, McNamara K, et al. The impact of human EGFR kinase domain mutations on lung tumorigenesis and in vivo sensitivity to EGFR-targeted therapies. Cancer Cell 2006;9:485—95. [8] Aoyagi Y, Yokose T, Minami Y, Ochiai A, Iijima T, Morishita Y, et al. Accumulation of losses of heterozygosity and multistep carcinogenesis in pulmonary adenocarcinoma. Cancer Res 2001;61:7950—4. [9] Yamasaki M, Takeshima Y, Fujii S, Matsuura M, Tagawa K, Inai K. Correlation between morphological heterogeneity and genetic alteration within one tumor in adenocarcinoma of the lung. Pathol Int 2000;50:891—6. [10] Yoshida Y, Shibata T, Kokubu A, Tsuta K, Matsuno Y, Kanai Y, et al. Mutations of the epidermal growth factor receptor gene in atypical adenomatous hyperplasia and bronchioloalveolar carcinoma of the lung. Lung Cancer 2005;50:1—8. [11] Lasota J, Vel Dobosz AJ, Wasag B, Wozniak A, Kraszewska E, Michej W, et al. Presence of homozygous KIT exon 11 mutations is strongly associated with malignant clinical behavior in gastrointestinal stromal tumors. Lab Invest, in press.
H. Nakano et al. [12] Shah NT, Kris MG, Pao W, Tyson LB, Pizzo BM, Heinemann MH, et al. Practical management of patients with non-small-cell lung cancer treated with gefitinib. J Clin Oncol 2005;23:1—10. [13] Pao W, Miller VA, Politi KA, Riely GJ, Somwar R, Zakowski MF, et al. Acquired resistance of lung adenocarcinomas to gefitinib or erlotinib is associated with a second mutation in the EGFR kinase domain. PLoS Med 2005;2:1—11. [14] Kobayashi S, Boggon TJ, Dayaram T, Janne PA, Kocher O, Meyerson M, et al. EGFR mutation and resistance of non-small-cell lung cancer to gefitinib. N Engl J Med 2005;352:786—92. [15] Chou WC, Huang SF, Yeh KY, Wang HM, Liu MY, Hsieh JJ, et al. Different responses to gefitinib in lung adenocarcinoma coexpressing mutant- and wild-type epidermal growth factor receptor genes. Jpn J Clin Oncol 2006;36:523—6. [16] Nagai Y, Miyazawa H, Huqun, Tanaka T, Udagawa K, Kato M, et al. Genetic heterogeneity of the epidermal growth factor receptor in non-small cell lung cancer cell lines revealed by a rapid and sensitive detection system, the peptide nucleic acid-locked nucleic acid PCR clamp. Clin Cancer Res 2005;65:7276—82.
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/lungcan
CASE REPORT
Heterogeneity of epidermal growth factor receptor mutations within a mixed adenocarcinoma lung nodule Hirofumi Nakano a, Hiroshi Soda a,b,∗, Mineyo Takasu c, Nanae Tomonaga a, Hiroyuki Yamaguchi a, Katsumi Nakatomi a, Satoru Fujino d, Tomayoshi Hayashi e, Yoichi Nakamura a, Kazuhiro Tsukamoto c, Shigeru Kohno a a
Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki 852-8501, Japan Division of Respiratory Medicine, Sasebo City General Hospital, Sasebo 857-8511, Japan c Department of Pharmacotherapeutics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8521, Japan d Internal Medicine, Saint Francisco Hospital, Nagasaki 852-8125, Japan e Department of Pathology, Nagasaki University Hospital, Nagasaki 852-8501, Japan b
Received 20 April 2007; received in revised form 14 August 2007; accepted 19 August 2007
KEYWORDS Lung cancer; Atypical adenomatous hyperplasia; Bronchioloalveolar carcinoma; Mixed adenocarcinoma; Epidermal growth factor receptor mutations; Gefitinib
Summary It has been proposed that stepwise progression occurs from atypical adenomatous hyperplasia (AAH) through bronchioloalveolar carcinoma (BAC) to invasive lung adenocarcinoma. However, the underlying molecular mechanisms have not been identified. We report a patient with a mixed adenocarcinoma of the lung that had different EGFR mutations in the papillary subtype, the acinar subtype, and the surrounding AAH and BAC areas. EGFR mutations may accumulate during tumor progression and lead to heterogeneity of EGFR mutations within the tumor. © 2007 Elsevier Ireland Ltd. All rights reserved.
1. Introduction ∗ Corresponding author at: Division of Respiratory Medicine, Sasebo City General Hospital, 9-3 Hirase, Sasebo 857-8511, Japan. Tel.: +81 956 24 1515; fax: +81 956 22 4641. E-mail address: [email protected] (H. Soda).
Lung adenocarcinoma with bronchioloalveolar carcinoma (BAC) features is frequently seen on thin-section chest computed tomography (CT) [1]. This type of adenocarcinoma is thought to develop from atypical adenomatous hyper-
0169-5002/$ — see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.lungcan.2007.08.021
Heterogeneity of epidermal growth factor receptor mutations within a mixed adenocarcinoma lung nodule
137
plasia (AAH) through BAC [1,2]. However, the molecular mechanism by which AAH and BAC evolve into invasive adenocarcinoma has not yet been determined. In BAC, mutations of the epidermal growth factor receptor (EGFR) gene are often observed [3—5]. Recently, two study groups have reported that transgenic mice bearing EGFR mutations develop BAC and lung adenocarcinoma [6,7]. Since EGFR mutations may be involved in the evolution of adenocarcinoma, it is important to know the EGFR mutation status in the various parts of a lung adenocarcinoma. We report a patient with different EGFR mutation patterns in the invasive adenocarcinoma and in the surrounding AAH and BAC areas.
2. Case report A 61-year-old, Japanese, female non-smoker was admitted for investigation of a nodule that was seen on chest radiography. A chest CT scan showed a 4-cm, solid nodule surrounded by ground-glass opacity (GGO) in the right upper lobe, along with enlargement of mediastinal lymph nodes (Fig. 1). A diagnosis of stage IIIA lung adenocarcinoma was made; the patient received combination chemotherapy followed by right upper lobectomy. Histological examination showed mixed adenocarcinoma with papillary and acinar subtypes and surrounding AAH and BAC areas (Fig. 2). On the CT scan, the AAH and BAC areas showed GGO, while the papillary and acinar subtypes formed the solid part of the nodule. Four months later, the patient developed mul-
Fig. 1 Transverse, thin-section, computed tomography scan shows a 4-cm, lobulated nodule consisting of a solid portion and ground-glass opacity with coarse spiculations in the right upper lung lobe.
tiple bilateral lung metastases. The patient was treated with several anti-cancer drugs. Two years after the recurrence was noted, the patient began taking gefitinib, an EGFR tyrosine kinase inhibitor. For 1 year, the pulmonary lesions improved remarkably, but then progressed. Gefitinib treatment was interrupted for 2 months, and then re-started. Though the lesions regressed for 1 month,
Fig. 2 Histological findings of the different areas of a resected lung nodule. (A) Atypical adenomatous hyperplasia, (B) bronchioloalveolar carcinoma, (C) papillary adenocarcinoma, and (D) acinar adenocarcinoma.
138
H. Nakano et al.
Fig. 3 Representation of the direct DNA sequencing for PCR products including hot-spot deletions in exon 19 of EGFR for each adenocarcinoma subtype. After electrophoresis on 6% acrylamide gel for PCR products, including heterozygous deletion in exon 19, DNA was extracted from shorter-sized PCR products that had a deletion, and was subsequently subjected to direct DNA sequencing. (A) Homozygous deletion in exon 19 in the papillary subtype; (B) heterozygous deletion in atypical adenomatous hyperplasia (AAH) and bronchioloalveolar carcinoma (BAC) subtype; and (C) no deletions in acinar, AAH, and BAC subtypes. Homozygous deletion ranged from E746 to A750 including 15 base-pair nucleotides (GGAATTAAGAGAAGC), compared with the no deletion sequence. In the AAH and BAC areas, the deletion involved in the heterozygous deletion was identical to that noted in the homozygous deletion in the papillary subtype (data not shown). Red vertical bars indicate deletion sites. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
they subsequently progressed, and the patient died despite treatment. The EGFR mutations were retrospectively analyzed using the microdissection technique for paraffin-embedded surgical specimens after obtaining the patient’s written informed consent. Four microdissected samples were obtained from the different parts of each histological subtype, and DNA extraction was performed using EXPATTM (Takara Bio Inc., Shiga, Japan); then, EGFR hot-spot mutation analysis was done. Deletion in exon 19 and the point mutations of both T790M in exon 20 and L858R in exon 21 were determined using the simple polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) methods, respectively. Our results indicate that there was only a deletion in exon 19; neither T790M nor L858R was affected. Deletions from E746 to A750 in exon 19 were confirmed by PCR-direct DNA sequencing analysis. The sequencing analysis indicated that the EGFR mutation status in each adenocarcinoma subtype was different (Table 1). The peripheral AAH and BAC areas showed either heterozygous deletion or no deletion in exon 19. In the central area of the nodule, the papillary subtype had both homozygous
and heterozygous deletions in exon 19, whereas the acinar subtype had no deletion (Fig. 3).
3. Discussion It has been proposed that a stepwise progression occurs from AAH through BAC to invasive adenocarcinoma [1,2]. In the current case, the peripheral AAH and BAC areas had a heterozygous deletion in exon 19, whereas the papillary subtype in the central areas of the nodule mainly had a homozygous deletion. There are two possible explanations for the heterozygosity found in the AAH and BAC areas: (1) the homozygous deletion was contaminated by wild-type DNA; or (2) it was a true heterozygous deletion. Several investigators have also reported that tumor cells in central areas exhibit more allelic losses than those in peripheral BAC areas [8,9]. EGFR mutations are less frequently observed in AAH and BAC areas, compared to areas of invasive adenocarcinoma [10]. A recent study has shown that, in gastrointestinal stromal tumors, the shift from heterozygous mutations in KIT exon 11 to homozygous mutations occurs during tumor
Heterogeneity of epidermal growth factor receptor mutations within a mixed adenocarcinoma lung nodule Table 1
139
EGFR mutations within a single tumor by histological subtype
Histological subtype (number of samples)
Homozygous deletion in exon 19
Heterozygous deletion in exon 19
No deletion
AAH areas (n = 4) BAC areas (n = 4) Papillary AD (n = 4) Acinar AD (n = 4)
0 0 3 0
2 2 1 0
2 2 0 4
AAH: atypical adenomatous hyperplasia, BAC: bronchioloalveolar carcinoma, AD: adenocarcinoma.
progression, and that the presence of homozygosity is associated with a worse disease course [11]. These findings support a hypothetical model of clonal evolution that starts with heterozygous deletion in exon 19 and progresses to homozygous deletion in papillary adenocarcinoma (Fig. 4). Furthermore, in the central areas, the papillary subtype had a deletion in exon 19, and acinar subtypes without EGFR mutations were observed; however, the peripheral AAH and BAC areas showed a mixture of deletions and no deletion in exon 19. These findings suggest that each subtype of lung adenocarcinoma develops through different carcinogenesis pathways, which leads to the heterogeneity of EGFR mutations in the tumor (Fig. 4). Since the patient received conventional chemotherapy pre-operatively, it is possible that conventional chemotherapy may have affected the status of the EGFR mutations. However, to the best of our knowledge, there are no reports that conventional chemotherapy induces additional mutations of EGFR. In addition, prior chemotherapy is not related to the effects of gefitinib [12]. Thus, neoadjuvant chemotherapy in the current case was unlikely to have affected the status of EGFR mutations.
In lung cancer patients, EGFR mutations are a predictor of clinical response to gefitinib. However, even though lung cancer patients with EGFR mutations are good responders, disease progression is inevitable and occurs within 1 year of therapy. Little is known about the mechanisms by which resistance to gefitinib develops in patients with EGFR mutations. Several investigators reported that the additional mutation of T790M is, at least in part, related to the acquisition of gefitinib resistance [13,14]. A recent case report showed different treatment responses to gefitinib in a patient with lung adenocarcinoma co-expressing a certain EGFR mutation in the primary lung tumor and a wildtype gene in metastatic bone lesions [15]. It is noteworthy that several lung cancer cell lines include cells without EGFR mutations and cells with certain EGFR mutations [16]. In the current report, based on the microdissection results, heterogeneity of EGFR mutations was also observed within the adenocarcinoma nodule. Heterogeneity of EGFR mutations within the tumor may be related to gefitinib response and resistance.
Conflict of interest None
References
Fig. 4 A hypothetical model of clonal evolution during the development of lung adenocarcinoma in the current case. There are two cell populations with either heterozygous deletion in exon 19 (shaded circle) or no deletion in exon 19 (open circle) in early neoplastic lesions such as atypical adenomatous hyperplasia (AAH) and bronchioloalveolar carcinoma (BAC). Acinar adenocarcinoma develops from the cell population with no deletion in exon 19, whereas papillary adenocarcinoma develops from cells with heterozygous deletion in exon 19. The shift from heterozygous deletion in exon 19 to homozygous deletion (closed circle) occurs during progression of papillary adenocarcinoma.
[1] Takeshima S, Maruyama Y, Hasegawa M, Yamanda T, Honda T, Kadoya M, et al. CT findings and progression of small peripheral lung neoplasms having a replacement growth pattern. Am J Roentgenol 2003;180:817—26. [2] Noguchi M, Morikawa A, Kawasaki M, Matsuno Y, Yamada T, Hirohashi S, et al. Small adenocarcinoma of the lung. Cancer 1995;75:2844—52. [3] Blons H, Cote JF, Le Corre D, Riquet M, Fabre-Guilevin E, Laurent-Puig P, et al. Epidermal growth factor receptor mutations in lung cancer are linked to bronchioloalveolar differentiation. Am J Surg Pathol 2006;30:1309—15. [4] Haneda H, Sasaki H, Shimizu S, Endo K, Suzuki E, Yukiue H, et al. Epidermal growth factor receptor gene mutation defines distinct subsets among small adenocarcinomas of the lung. Lung Cancer 2006;52:47—52. [5] Matsumoto S, Iwakawa R, Kohno T, Suzuki K, Matsuno Y, Yamamoto S, et al. Frequent EGFR mutations in noninvasive bronchioloalveolar carcinoma. Int J Cancer 2006;118:2498—504. [6] Politi K, Zakowski MF, Fan PD, Schonfeld EA, Pao W, Varmus HE. Lung adenocarcinomas induced in mice by mutant EGF receptors found in human lung cancers respond to a tyrosine kinase inhibitor or to down-regulation of the receptors. Genes Dev 2006;20:1496—510.
140 [7] Ji H, Li D, Chen L, Shimamura T, Kobayashi S, McNamara K, et al. The impact of human EGFR kinase domain mutations on lung tumorigenesis and in vivo sensitivity to EGFR-targeted therapies. Cancer Cell 2006;9:485—95. [8] Aoyagi Y, Yokose T, Minami Y, Ochiai A, Iijima T, Morishita Y, et al. Accumulation of losses of heterozygosity and multistep carcinogenesis in pulmonary adenocarcinoma. Cancer Res 2001;61:7950—4. [9] Yamasaki M, Takeshima Y, Fujii S, Matsuura M, Tagawa K, Inai K. Correlation between morphological heterogeneity and genetic alteration within one tumor in adenocarcinoma of the lung. Pathol Int 2000;50:891—6. [10] Yoshida Y, Shibata T, Kokubu A, Tsuta K, Matsuno Y, Kanai Y, et al. Mutations of the epidermal growth factor receptor gene in atypical adenomatous hyperplasia and bronchioloalveolar carcinoma of the lung. Lung Cancer 2005;50:1—8. [11] Lasota J, Vel Dobosz AJ, Wasag B, Wozniak A, Kraszewska E, Michej W, et al. Presence of homozygous KIT exon 11 mutations is strongly associated with malignant clinical behavior in gastrointestinal stromal tumors. Lab Invest, in press.
H. Nakano et al. [12] Shah NT, Kris MG, Pao W, Tyson LB, Pizzo BM, Heinemann MH, et al. Practical management of patients with non-small-cell lung cancer treated with gefitinib. J Clin Oncol 2005;23:1—10. [13] Pao W, Miller VA, Politi KA, Riely GJ, Somwar R, Zakowski MF, et al. Acquired resistance of lung adenocarcinomas to gefitinib or erlotinib is associated with a second mutation in the EGFR kinase domain. PLoS Med 2005;2:1—11. [14] Kobayashi S, Boggon TJ, Dayaram T, Janne PA, Kocher O, Meyerson M, et al. EGFR mutation and resistance of non-small-cell lung cancer to gefitinib. N Engl J Med 2005;352:786—92. [15] Chou WC, Huang SF, Yeh KY, Wang HM, Liu MY, Hsieh JJ, et al. Different responses to gefitinib in lung adenocarcinoma coexpressing mutant- and wild-type epidermal growth factor receptor genes. Jpn J Clin Oncol 2006;36:523—6. [16] Nagai Y, Miyazawa H, Huqun, Tanaka T, Udagawa K, Kato M, et al. Genetic heterogeneity of the epidermal growth factor receptor in non-small cell lung cancer cell lines revealed by a rapid and sensitive detection system, the peptide nucleic acid-locked nucleic acid PCR clamp. Clin Cancer Res 2005;65:7276—82.