Received EGFR-tyrosine Kinase Inhibitors Research Articles

Clinical activity and safety of HM61713, an EGFR-mutant selective inhibitor, in advanced non-small cell lung cancer (NSCLC) patients (pts) with EGFR mutations who had received EGFR tyrosine kinase inhibitors (TKIs).

8011 Background: HM61713 is a novel, oral, selective inhibitor for EGFR mutations including both activating mutations and T790M, but not EGFR wild-type. This phase 1 trial was conducted to evaluate...

EGFR-activating mutations and treatment with tyrosine-kinase inhibitors (TKI) to revert poor-prognosis (PP) associated with liver metastases (LM) in stage IV non-small cell lung cancer (NSCLC) patients (pts).

e19106 Background: LM appear in 20-30% of pts diagnosed with NSCLC and they confer PP. However, whether the clinical outcome of NSCLC pts with LM harboring molecular alterations in EGFR, KRAS and EML4-ALK genes is substantially different depending on their distinct status is still unknown. Methods: A total of 268 consecutive stage IV NSCLC pts were included. The tumor molecular analysis for EGFR, KRAS and EML4-ALK was available in 205 pts (76.5%), 136 pts (50.7%) and 31 pts (11.6%), respectively. An EGFR mutation was observed in 32 pts (15.6%), KRAS was mutated in 28 pts (20.6%) and EML4-ALK gene rearrangement was observed in 3 pts (9.6%). We aimed to determine whether the molecular status of EGFR, KRAS and EML4-ALK has an impact on the clinical outcome of stage IV NSCLC pts. Results: Most of the pts were men (71.3%). The most common histology was adenocarcinoma (59.3%). Overall, 34% of the pts showed LM at any time of the disease course. Among the whole cohort, median OS for LM pts was 16 months vs 42 months for pts with metastases other than LM (p<0.001). Among pts with LM and EGFR mutations, the one-year survival rate was 85.7% vs 54.3% for pts with LM and EGFR wild-type (p=0.03). We analyzed whether pts received EGFR TKI or standard chemotherapy (SC). For the subgroup of pts carrying EGFR mutations and receiving TKI, the 18-month survival rate was 75% for those showing LM vs 80% (p=0.44) for those without LM. In contrast, for the subgroup of EGFR wild-type pts receiving SC, the 18-month survival rate was 32.4% for those showing LM vs 74.9% for those without LM (p<0.001). No impact of KRAS or EML4-ALK molecular alterations on OS of pts with LM was observed. Conclusions: The presence of LM at any time of the disease curse negatively impacts on the clinical outcome of NSCLC pts. However, the presence of EGFR activating mutations significantly improves the OS of those with liver spread, reaching a similar OS to subjects with no LM. Pts with EGFR mutations and LM may revert the PP associated to LM when an EGFR TKI is prescribed.

Abstract 971: Synergistic effect of c-Met inhibitor volitinib in combination with EGFR inhibitor Gefitnib on EGFR-TKI resistant NSCLC model HCC827C4R harboring acquired Met gene amplification.

Abstract It is well recognized that non-small cell lung carcinoma (NSCLC) patients with activating EGFR mutations will develop drug resistance after receiving EGFR-tyrosine kinase inhibitors (EGFR-TKI). About 20% of those patients with TKI resistance were identified to harbor Met gene amplification. The aim of this study includes two aspects: a) generating an acquired c-Met amplified EGFR-TKI resistant tumor line in preclinical setting, and b) exploring combination effect of c-met inhibitor volitinib and EGFR inhibitor gefitinib on the new tumor line. Volitinib is a novel, highly potent and selective c-Met inhibitor, currently being evaluated in the phase I clinical trial. HCC827(exon 19 del E746-A750), a human NSCLC cell line, was treated with increasing concentrations of EGFR inhibitor for about 6 months and gradually produced the resistance to EGFR-TKIs, such as gefitinib and erlotinib. One of the subclones, HCC827C4R was isolated and was confirmed to carry Met gene amplification in comparison to parent cell line HCC827. It was not sensitive to volitinib treatment in cell survival assay due to dual activation of EGFR and c-Met pathways. The results from signal pathway study demonstrated that in HCC827C4R cells, volitinib or gefitinib alone only inhibited the phosphorylation of c-Met or EGFR, respectively, but had no effect on the activation of downstream molecules such as Akt and ERK which drive tumor cell proliferation and other cell functions. In contrast, combination of volitinib and gefitinib significantly inhibited phosphorylation of EGFR, c-Met, Akt and ERK in HCC827C4R, and consequently led to a synergistic effect on inhibiting tumor cell growth in vitro. These results were further confirmed in HCC827C4R xenograft model in vivo at clinically relevant doses. Combination of volitinib and gefitinib induced significant tumor regression and displayed synergistic effect compared to treatment by either gefitinib or volitinib alone. Consistent with in vitro results, combination group strongly inhibited the downstream Akt and ERK phosphorylation. In addition, combination treatment was well tolerant and no significant drug-drug exposure interaction was observed. These data indicated that both c-Met and EGFR could contribute to activating downstream signaling pathway and control HCC827C4R cell growth. Blocking either pathway may not be strong enough to stop tumor growth. In conclusion, a cell line with activating EGFR mutation and c-Met gene amplification was generated with resistance to gefitinib and insensitivity to volitinib. The combination treatment with volitinib and an EGFR inhibitor gefitinib was highly effective in vitro and in vivo, suggesting that such combination could provide a safe and effective treatment in clinics for this particular patient population. Citation Format: Feng Zhou, Yongxin Ren, Yumin Cui, Hanyang Chen, Longxian Jiao, Guangxiu Dai, Shiming Fan, Junen Sun, Yongjuan Yu, Yang Sai, Yi Gu, Weiguo Qing, Weiguo Su. Synergistic effect of c-Met inhibitor volitinib in combination with EGFR inhibitor Gefitnib on EGFR-TKI resistant NSCLC model HCC827C4R harboring acquired Met gene amplification. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 971. doi:10.1158/1538-7445.AM2013-971

Can Serum be Used for Analyzing the EGFR Mutation Status in Patients with Advanced Non-small Cell Lung Cancer?

Epidermal growth factor receptor (EGFR) mutations as prognostic or predictive marker in patients with non-small cell lung cancer (NSCLC) have been used widely. However, it may be difficult to get tumor tissue for analyzing the status of EGFR mutation status in large proportion of patients with advanced disease. We obtained pairs of tumor and serum samples from 57 patients with advanced NSCLC, between March 2006 and January 2009. EGFR mutation status from tumor samples was analyzed by genomic polymerase chain reaction and direct sequence and EGFR mutation status from serum samples was determined by the peptide nucleic acid locked nucleic acid polymerase chain reaction clamp. EGFR mutations were detected in the serum samples of 11 patients and in the tumor samples of 12 patients. EGFR mutation status in the serum and tumor samples was consistent in 50 of the 57 pairs (87.7%). There was a high correlation between the mutations detected in serum sample and the mutations detected in the matched tumor sample (correlation index 0.62; P<0.001). Twenty-two of 57 patients (38.5%) received EGFR-tyrosine kinase inhibitors as any line therapy. The response for EGFR-tyrosine kinase inhibitors was significantly associated with EGFR mutations in both tumor samples and serum samples (P<0.05). There was no significant differences in overall survival according to the status of EGFR mutations in both serum and tumor samples (P>0.05). Serum sample might be alternatively used in the difficult time of getting tumor tissue for analyzing the status of EGFR mutation status in patients with advanced NSCLC.

Who should receive EGFR tyrosine-kinase inhibitors?

Who should receive EGFR tyrosine-kinase inhibitors?

O2-023 - Prognostic Factors in Non-Small-Cell Lung Cancer (NSCLC) Patients with Epidermal Growth Factor Receptor (EGFR) Mutations: Data from the Randomized Phase III Study Compared Gefitinib with Carboplatin Plus Paclitaxel (NEJ002)

ABSTRACT Background In the NEJ002 study comparing first-line gefitinib to a standard-chemotherapy of carboplatin plus paclitaxel for advanced NSCLC patients with tumors harboring sensitive EGFR mutations, progression-free survival was significantly longer in the gefitinib group compared with the standard-chemotherapy group. However, as 98% of the patients in whom first-line carboplatin-paclitaxel failed crossed over to gefitinib therapy, the overall survival was similar between the two groups. The 2.5-year survival rate of both groups in NEJ002 were very good at about 50%. In order to clarify the factors which contribute to the long-term survival of NSCLC patients with mutated EGFR, we evaluated any correlation between demographic factors and overall survival outcome in 230 patients enrolled in NEJ002. Methods The analysis was performed independently from our previous reports. A total of 226 patients who received EGFR-tyrosine kinase inhibitors (TKI) and had survival confirmation were analyzed. Fourteen factors were evaluated using the cause-specific survival, and uni- and multi-variate analyses were conducted by Cox's proportional hazard model. Results Four prognostic factors were identified by univariate analysis: base-line performance status (PS), existence of the distant metastasis, response to standard-chemotherapy and EGFR-TKI (P Conclusion Base-line PS, responses to standard chemotherapy and response to EGFR-TKI were significant factors on the prognosis of NSCLC with sensitive EGFR mutations. Using updated survival data, a logistic regression analysis for long survivors (more than 3 years) will be presented. Disclosure A. Inoue: I was paid lecture fees from AstraZeneca. S. Oizumi: I was paid an honorarium (AstraZeneca). K. Hagiwara: I was paid honoraria from AstraZeneca. A. Gemma: I (my department) received grant for basic research by AstraZeneca as a chief of department. All other authors have declared no conflicts of interest.

Survival of lung adenocarcinoma patients with malignant pleural effusion

In the era of targeted therapy, the association between lung adenocarcinoma patient survival and malignant pleural effusions (MPEs) remains unclear. This study investigated the clinical characteristics, survival and epidermal growth factor receptor (EGFR) gene (EGFR) mutation status of lung adenocarcinoma patients with MPE. From June 2005 to December 2010, consecutive pleural effusions were collected prospectively. Patient clinical characteristics, EGFR mutation status, and overall survival were analysed. We collected MPEs from 448 patients in stage IV lung adenocarcinoma at initial diagnosis. Median overall survival for patients with MPEs at initial diagnosis and following disease progression were 14.3 months and 21.4 months, respectively (p=0.001). There were 296 (66.1%) patients harbouring EGFR mutations, the mutation rates among patients with an MPE at initial diagnosis and one following disease progression were 68.2% and 56.6%, respectively (p=0.044); the L858R mutation rate was also higher among the former (32.6% versus 18.1%; p=0.009). Multivariate analysis revealed that patients who: developed MPEs following disease progression, harboured EGFR mutations, and received EGFR-tyrosine kinase inhibitor therapy, had longer overall survival. Patients in stage IV lung adenocarcinoma with MPEs at initial diagnosis have shorter overall survival and higher EGFR mutation rate, especially for L858R, than patients who develop MPEs following disease progression.

1256P - Long-Term Survivors in Non-Small Cell Lung Cancer (NSCLC) Patients with Epidermal Growth Factor Receptor (EGFR) Mutations: Data from a Randomized Phase III Study Comparing GEFITINIB with Carboplatin Plus Paclitaxel (NEJ002)

ABSTRACT Background In the NEJ002 study comparing first-line gefitinib to a standard-chemotherapy of carboplatin plus paclitaxel for advanced NSCLC patients with tumors harboring sensitive EGFR mutations, progression-free survival was significantly longer in the gefitinib group compared with the standard-chemotherapy group. However, as 98% of the patients in whom first-line carboplatin-paclitaxel failed crossed over to gefitinib therapy, the overall survival was similar between the two groups. The 2.5-year survival rate of both groups in NEJ002 were very good at about 50%. In order to clarify the factors which contribute to the long-term survival of NSCLC patients with mutated EGFR, we evaluated any correlation between demographic factors and overall survival outcome in 230 patients enrolled in NEJ002. Methods The analysis was performed independently from our previous reports. A total of 226 patients who received EGFR-tyrosine kinase inhibitors (TKI) and had survival confirmation were analyzed. Fourteen factors were evaluated using the cause-specific survival, and uni- and multi-variate analyses were conducted by Cox's proportional hazard model. Results Four prognostic factors were identified by univariate analysis: base-line performance status (PS), existence of the distant metastasis, response to standard-chemotherapy and EGFR-TKI (P Conclusion Base-line PS, responses to standard chemotherapy and response to EGFR-TKI were significant factors on the prognosis of NSCLC with sensitive EGFR mutations. Using updated survival data, a logistic regression analysis for long survivors (more than 3 years) will be presented. Disclosure A. Inoue: I was paid lecture fees from AstraZeneca. S. Oizumi: I was paid an honorarium (AstraZeneca). K. Hagiwara: I was paid honoraria from AstraZeneca. A. Gemma: I (my department) received grant for basic research by AstraZeneca as a chief of department. All other authors have declared no conflicts of interest.

1270P - Mutact: An Observational Study of EGFR Mutation Status and Management of Patients with Non-Small Cell Lung Cancer (NSCLC) Adenocarcinoma

ABSTRACT Background Certain mutations in the EGFR gene predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs) in advanced NSCLC, and are more common in adenocarcinoma than other histologies. When this study was planned, epidemiological data on EGFR mutations were mostly derived from Asian studies. MUTACT aims to determine the frequency of EGFR mutation positive (EGFR M+) cases in a cohort of French patients with NSCLC adenocarcinoma, and the clinical outcomes of patients with EGFR M+ disease. Methods All patients ≥18 years old with NSCLC adenocarcinoma and a planned EGFR mutation test were eligible for this observational study (NCT01167972, AstraZeneca sponsored). Demographics, disease characteristics and EGFR mutation status were recorded for all patients. Follow-up for treatment decisions and clinical outcomes for patients with EGFR M+ disease is ongoing. Results Between Sept 2010 and Aug 2011, 1382 patients were enrolled at 76 sites in France. Baseline characteristics were: male (57%), Caucasian (95%) and stage IV disease (79%), including more smokers (38%) than never-smokers (30%) or ex-smokers (29%). EGFR M + /M-/non-evaluable (Mx) disease rates were respectively 20.6%, 76.1% and 3.3%. Most samples were analysed by direct sequencing (69%) using primary tumour tissue (77%), with a median turnover time of 12 days. Patients with EGFR M+ disease were mostly female (67%) and never-smokers (70%). As expected, the majority of mutations were detected at exons 19 (54%) and 21 (37%), but mutations were also found at exons 18 (3%) and 20 (7%). Overall, 1% patients had mutations conferring decreased sensitivity to EGFR TKIs (exon 20). At inclusion, 633 patients (46%) were in 1st line treatment (others had surgery or were in 2nd/3rd line). Of the 283 patients with EGFR M+ disease, 186 (66%) were in 1st line treatment at inclusion; 158 (84%) of these received EGFR TKI. Conclusions MUTACT provides a large epidemiological database of predominantly Caucasian patients with NSCLC. More females and never-smokers than expected in an adenocarcinoma population were included, resulting in a high EGFR M+ rate. EGFR TKIs were the most common 1st line treatment in patients with EGFR M+ disease. Disclosure P. Souquet: P-J Souquet is currently conducting research sponsored by AstraZeneca. He has also participated in several boards with AstraZeneca and has received fundings from AstraZeneca. J.C. Sabourin: J-C Sabourin is a member of a scientific board for AstraZeneca and has received funding for research from AstraZeneca. E. Garcia: E Garcia is an employee of AstraZeneca. M. Licour: M Licour is an employee of AstraZeneca. N. Karam: N Karam is an employee of AstraZeneca. All other authors have declared no conflicts of interest.

Two genetic polymorphisms of EGFR as useful predictive biomarkers for NSCLC patients receiving EGFR TKIs.

e18050 Background: The EGFR mutation on particular exons has been known as a strong predictive biomarker to EGFR TKIs (tyrosine kinase inhibitors) in NSCLC pts. However, some pts having wild type EGFR do not infrequently show clinically favorable outcome to EGFR TKIs. Accordingly, we hypothesized that clinical outcome and skin toxicity to EGFR TKIs might be related to specific single nucleotide polymorphisms regulating the expression of EGFR gene as well as EGFR sensitive mutation. Methods: In 211 advanced or metastatic NSCLC pts receiving gefitinib or erlotinib, we assayed mutation status of EGFR in paraffin embedded tumor tissue using PNA clamping method and direct sequencing. Six different SNPs in genomic DNA extracted from peripheral blood were analyzed; promoter 191C&gt;A, 216 G&gt;T, CA repeat number, exon 13 R497K, exon 20 2607G&gt;A, and exon 25 D994D. Results: M:F ratio was 106:105 and mean age was 63.2 (35.0-82.0). Histological subtypes are as follows: 175 adenocarcinoma, 32 squamous cell ca. and 3 large cell ca. Objective response (CR+PR) was observed in 78 pts (36.9%) and SD in 69 pts (32.7%). Median PFS and OS were 8.7 ± 11.3 and 15.9 ± 14.8 months, respectively. Of 167 pts in whom EGFR mutation was analyzed, 68 pts (40.7%) had EGFR harboring sensitive mutation. In R497K, wild type (RR) was 35 (21.0%) and K alleles (RK + KK) were 132 (79.0%). In D994D, wild type (GG) was 76 (45.5%) and heterozygote and homozygote variants (GA+AA) were 91(54.5%). Statistically significant differences of PFS and OS were observed between wild and hetero-/homozygote variants of R497K (11.9 m vs. 36.2 m, p=0.037 and 23.7 m vs. 39.1 m, p=0.054, respectively) in the pts harboring mutant type EGFR. Meanwhile, in the pts harboring wild type EGFR, GA+ AA genotype of D994D demonstrated much longer PFS and OS compared with GG genotype (PFS: 18.5 vs. 3.7 m, p=0.013 and 37.6 vs. 15.2 m, p=0.035, respectively). In addition, skin rash showed statistically significant association with R497K polymorphism (P=0.031). Conclusions: Our data suggest that two germline genetic variations of EGFR gene, R497K and D994D, be useful pharmacogenetic biomarker to predict longer PFS and OS for EGFR TKIs in advanced NSCLC pts harboring mutant type and wild type EGFR, respectively.

Intratumoral heterogeneity of EGFR mutation and clinical significance in Chinese patients with advanced non-small cell lung cancer.

7537 Background: Whether exist intratumoral heterogeneity of epidermal growth factor receptor (EGFR) gene mutation remains controversial. This study aims to evaluate intratumoral heterogeneity of EGFR and its clinical significance in patients with non-small cell lung cancer (NSCLC). Methods: Samples were collected from 85 patients with stage IIIa-IV who had palliative surgery resection. All of the bulk tissues had been routinely detected EGFR mutation, in which contained 30 wild-type and 55 mutant-type EGFR. 28–34 tumor foci for each sample were microdissected. EGFR mutation was detected by ARMS. EGFR copy number was detected by FISH. 23 patients received EGFR-tyrosine kinase inhibitor (TKIs) therapy. Results: 1740 tumor foci from 55 EGFR mutant-type (Group-M) and 959 foci from 30 wild-type cases(Group-W) were fractionated. Mean mutation contents were 73.9%(1285/1740) in Group-M and 0 in Group-W. Accordingly, 28.2%(24/85)consisted of cells with both wild-type and mutated-type EGFR, with the proportion of EGFR mutant cells ranging from 1% to 90%, whereas 71.8%(61/85) samples contained pure mutant-type (n=31) or wild-type EGFR cells(n=30). 31 patients (36.5%) presented EGFR FISH positive. The patients with mutation heterogeneity, regardless of high or low mutation contents, presented lower EGFR copy number than those with pure mutation cases (16.7% vs 71.0%,p&lt;0.05). Among 23 patients who received EGFR-TKIs therapy, the mean mutation content was higher in partial response (71.1%) and stable disease group (43.4%) than in progressive disease group (5.0%) (p=0.005). Conclusions: This study showed that the heterogeneity of EGFR mutation was found in introtumoral region with different degree. The response to EGFR-TKIs was correlated with EGFR mutant content.

Clinical outcome in patients with leptomeningeal metastasis from non-small cell lung cancer: Okayama Lung Cancer Study Group

ObjectiveWe examined the prognosis of patients with leptomeningeal metastasis (LM) from non-small cell lung cancer (NSCLC) and that stratified by epidermal growth factor receptor (EGFR) mutation status in LM patients receiving EGFR-tyrosine kinase inhibitors (TKIs). MethodsWe retrospectively analyzed a series of 91 consecutive NSCLC patients with LM between 2001 and 2010. ResultsMost of the LM patients had adenocarcinoma histology and a poor performance status (PS). The median survival time (MST) for all patients was 3.6 months. Adenocarcinoma and TKI treatment were associated with a better prognosis. Among the patients, 51 received EGFR-TKIs. Of these, the EGFR mutation status was assessed in 30 patients; 7 (23%) showed no mutation (group 1), 10 (33%) had a mutation in exon 21 (group 2), and 13 (43%) had deletions in exon 19 (group 3). Interestingly, PS was significantly improved in groups 2 and 3 but not in group 1. The MST in these subgroups was 1.4, 7.1, and 11.0 months in groups 1, 2, and 3, respectively (p<0.001). The median time to progression or symptom deterioration was 0.9, 2.0, and 7.8 months for groups 1, 2, and 3, respectively (p<0.001). A multivariate analysis showed that EGFR-mutant tumors were associated with a better prognosis in patients receiving EGFR-TKIs. ConclusionsThe prognosis for patients with LM from NSCLC was still poor. Survival after the initiation of EGFR-TKI treatment differed according to the type of EGFR mutation, suggesting the potential benefit of TKIs for patients with EGFR mutations, even though they suffered from LM.

Proteomic Biomarkers for Acute Interstitial Lung Disease in Gefitinib-Treated Japanese Lung Cancer Patients

Interstitial lung disease (ILD) events have been reported in Japanese non-small-cell lung cancer (NSCLC) patients receiving EGFR tyrosine kinase inhibitors. We investigated proteomic biomarkers for mechanistic insights and improved prediction of ILD. Blood plasma was collected from 43 gefitinib-treated NSCLC patients developing acute ILD (confirmed by blinded diagnostic review) and 123 randomly selected controls in a nested case-control study within a pharmacoepidemiological cohort study in Japan. We generated ∼7 million tandem mass spectrometry (MS/MS) measurements with extensive quality control and validation, producing one of the largest proteomic lung cancer datasets to date, incorporating rigorous study design, phenotype definition, and evaluation of sample processing. After alignment, scaling, and measurement batch adjustment, we identified 41 peptide peaks representing 29 proteins best predicting ILD. Multivariate peptide, protein, and pathway modeling achieved ILD prediction comparable to previously identified clinical variables; combining the two provided some improvement. The acute phase response pathway was strongly represented (17 of 29 proteins, p = 1.0×10−25), suggesting a key role with potential utility as a marker for increased risk of acute ILD events. Validation by Western blotting showed correlation for identified proteins, confirming that robust results can be generated from an MS/MS platform implementing strict quality control.

Do Complex Mutations of the Epidermal Growth Factor Receptor Gene Reflect Intratumoral Heterogeneity?

In our clinical practice, two different epidermal growth factor receptor (EGFR) gene mutations are occasionally found in a single tumor sample. Such co-occurring EGFR mutations have been termed “complex mutations,” and we have previously reported the incidence and efficacy of gefitinib for patients with complex mutations.1Hata A Yoshioka H Fujita S et al.Complex mutations in the epidermal growth factor receptor gene in non-small cell lung cancer.J Thorac Oncol. 2010; 5: 1524-1528Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar In our previous article, we discussed the cause of complex mutations and speculated on the existence of intratumoral heterogeneity for EGFR mutations. We recently encountered three cases that support our hypothesis and herein present these cases. Case 1 was a 68-year-old man. He received a computed tomography-guided lung biopsy due to a suspicion of lung cancer. We performed a fine needle aspiration, followed by a core needle biopsy through a guide needle to obtain both cytological fluid and histological tissue (Figure 1). Although both cytology and histology revealed adenocarcinoma cells, we accidentally performed EGFR mutational analysis on both specimens. Interestingly, only a point mutation in exon 21 (L858R) was detected in the cytology, but complex mutations consisting of a point mutation in exon 18 (G719S) and L858R were detected in the histology. After a diagnosis of locally advanced disease, the patient underwent concurrent chemoradiation therapy. After the treatment, he has been observed and has not yet received EGFR-tyrosine kinase inhibitor (TKI) therapy. Case 2 was a 66-year-old woman. She was diagnosed with lung adenocarcinoma and underwent surgery as the initial therapy. EGFR mutational analysis in the surgical tissue revealed complex mutations consisting of a deletional mutation in exon 19 (Del-19) and L858R. After recurrence, she underwent multiple chemotherapies including EGFR-TKIs. In the course of treatment, she complained of gait disturbance and neck stiffness. Brain magnetic resonance imaging showed leptomeningeal metastases (Figure 2), and a lumbar puncture was performed. Unexpectedly, Del-19 disappeared, and only L858R was detected by EGFR mutational analysis of malignant cells in the cerebral spinal fluid. Rechallenge treatment with erlotinib was administered, and the clinical benefit has continued for 4 months. Case 3 was an 81-year-old man. He was initially diagnosed with lung adenocarcinoma with pleural disseminations. EGFR mutational analysis of the primary tumor showed complex mutations consisting of Del-19 and L858R. Considering the patient's age, gefitinib was chosen as the first-line treatment. Primary tumor and pleural disseminations markedly responded to gefitinib for approximately 20 months. However, the right pleural effusion has recently increased (Figure 3), and the cytology of pleural effusion revealed adenocarcinoma cells. Similarly, Del-19 disappeared, and both L858R and a point mutation in exon 20 (T790M) were detected by EGFR mutational analysis of the pleural effusion. Chest tube drainage has been carried out. Case 1 implies the existence of heterogeneous EGFR mutations in a single tumor: cytological fluid cells harboring only L858R and histological tissue cells harboring both G719S and L858R simultaneously existed in a single tumor. The intratumoral heterogeneity of EGFR mutation has been previously reported; both EGFR mutated and wild-type malignant cells were confirmed in a single tumor tissue in the report.2Sakurada A Lara-Guerra H Liu N et al.Tissue heterogeneity of EGFR mutation in lung adenocarcinoma.J Thorac Oncol. 2008; 3: 527-529Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar In cases 2 and 3, although complex mutations consisting of Del-19 and L858R were detected at the initial EGFR mutational analysis, Del-19 has disappeared and L858R remained after EGFR-TKI treatments. Higher sensitivity to EGFR-TKIs in patients with Del-19 than L858R has been demonstrated in several reports.3Jackman DM Yeap BY Sequist LV et al.Exon 19 deletion mutations of epidermal growth factor receptor are associated with prolonged survival in non-small cell lung cancer patients treated with gefitinib or erlotinib.Clin Cancer Res. 2006; 12: 3908-3914Crossref PubMed Scopus (486) Google Scholar If Del-19 and L858R cells had existed separately, Del-19 cells would have responded to EGFR-TKIs better than L858R cells, and L858R cells might have remained. Our present cases exhibiting these complex mutations suggest the intratumoral heterogeneity of EGFR mutations. Considering intratumoral heterogeneity consisting of EGFR-sensitive-mutated cells and wild-type or EGFR-resistant-mutated cells, the detection of EGFR mutations using a highly sensitive polymerase chain reaction method from small biopsies may not always reflect whole tumor sensitivity to EGFR-TKIs.4Travis WD Rekhtman N Riley GJ et al.Pathologic diagnosis of advanced lung cancer based on small biopsies and cytology: a paradigm shift.J Thorac Oncol. 2010; 5: 411-414Abstract Full Text Full Text PDF PubMed Scopus (147) Google Scholar However, our data were taken from only a few cases, and further research is needed. The clinical significance of intratumoral heterogeneity warrants future studies.