Disappearance of an activated EGFR mutation after treatment with EGFR tyrosine kinase inhibitors

Conversion from Positive to Negative EGFR Mutation due to Clonal Selection during Long-Term Treatment with Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors: A Case Report

A 77-year-old woman with postoperative recurrent non-small cell lung adenocarcinoma, which exhibited an epidermal growth factor receptor (EGFR) L858R mutation, was treated with gefitinib and erlotinib. Seven years after the start of treatment, the patient experienced a recurrence of malignant pleural effusion. However, 3 different genetic tests revealed that the lung adenocarcinoma cells in the pleural effusion had lost EGFR L858R mutation, suggesting that long-term treatment with EGFR-tyrosine kinase inhibitors (TKIs) converted EGFR mutation from positive to negative. The negative conversion of EGFR mutation as a mechanism of acquired resistance to EGFR-TKIs is considered rare and needs to be further investigated.

Non-significant efficacy of icotinib plus pleurodesis in epidermal growth factor receptor positive mutant lung cancer patients after malignant pleural effusion drainage compared to icotinib alone

Background

To investigate the efficacy and safety of icotinib plus pleurodesis or icotinib alone in epidermal growth factor receptor (EGFR) positive mutant lung cancer patients after malignant pleural effusion (MPE) drainage.

Methods

In this retrospective study from initially reviewed case reports of 230 lung adenocarcinoma patients with MPE who were EGFR mutation positive and treated in our hospital between Jan 2014 and Dec 2016 consecutively, 51 patients who met the inclusion criteria were divided into treated with oral icotinib plus pleurodesis and without pleurodesis after pleural effusion drainage groups. Case records including patient gender, age, smoking status and local treatments, as well as adverse events were collected and retrospectively analyzed. The clinical outcomes which were measured by progression free survival (PFS), objective response rate (ORR) & adverse reactions were analyzed by a Kaplan-Meier curve and a log-rank test after follow-ups.

Results

The median PFS of patients who received icotinib plus pleurodesis was 8.4 months, while the median PFS of icotinib alone patients was 9.0 months (P=0.996, χ²=7.241). Similarly, the ORR for MPEs, with or without pleurodesis were not significantly difference (64.29% vs. 67.57%, P=0.824, χ²=0.049). Adverse reactions of pleurodesis were mainly fever, chest pain, gastrointestinal reactions and myelosuppression.

Conclusions

Our results suggested that pleurodesis after MPE drainage had no difference on outcomes of icotinib therapy patients. However, pleurodesis may increase some adverse reactions, which might be inconvenient for patients in clinical practice.

Assessment of real-time PCR method for detection of EGFR mutation using both supernatant and cell pellet of malignant pleural effusion samples from non-small-cell lung cancer patients

BACKGROUND

EGFR mutation is an emerging biomarker for treatment selection in non-small-cell lung cancer (NSCLC) patients. However, optimal mutation detection is hindered by complications associated with the biopsy procedure, tumor heterogeneity and limited sensitivity of test methodology. In this study, we evaluated the diagnostic utility of real-time PCR using malignant pleural effusion samples.

METHODS

A total of 77 pleural fluid samples from 77 NSCLC patients were tested using the cobas EGFR mutation test (Roche Molecular Systems). Pleural fluid was centrifuged, and separated cell pellets and supernatants were tested in parallel. Results were compared with Sanger sequencing and/or peptide nucleic acid (PNA)-mediated PCR clamping of matched tumor tissue or pleural fluid samples.

RESULTS

All samples showed valid real-time PCR results in one or more DNA samples extracted from cell pellets and supernatants. Compared with other molecular methods, the sensitivity of real-time PCR method was 100%. Concordance rate of real-time PCR and Sanger sequencing plus PNA-mediated PCR clamping was 98.7%.

CONCLUSIONS

We have confirmed that real-time PCR using pleural fluid had a high concordance rate compared to conventional methods, with no failed samples. Our data demonstrated that the parallel real-time PCR testing using supernatant and cell pellet could offer reliable and robust surrogate strategy when tissue is not available.

Pleural involvement in lung cancer

The pleural space, a sterile secluded environment in the thoracic cavity, represents an attractive metastatic site for various cancers of lung, breast and gastrointestinal origins. Whereas lung and breast adenocarcinomas could invade the pleural space because of their anatomic proximity, "distant" cancers like ovarian or gastrointestinal tract adenocarcinomas may employ more active mechanisms to the same end. A pleural metastasis is often accompanied by a malignant pleural effusion (MPE), an unfavorable complication that severely restricts the quality of life and expectancy of the cancer patient. MPE is the net "product" of three different processes, namely inflammation, enhanced angiogenesis and vascular leakage. Current efforts are focusing on the identification of cancer cell autocrine (specific mutation spectra and biochemical pathways) and paracrine (cytokine and chemokine signals) characteristics as well as host features (immunological or other) that underlie the MPE phenotype. Herein we examine the pleural histology, cytology and molecular characteristics that make the pleural cavity an attractive metastasis destination for lung adenocarcinoma. Mesothelial and tumor features that may account for the tumor's ability to invade the pleural space are highlighted. Finally, possible therapeutic interventions specifically targeting MPE are discussed.

Influence of chemotherapy on EGFR mutation status

Lung cancer is the leading cause of cancer death in the world. The frequency of epidermal growth factor receptor (EGFR) mutations in non-small-cell lung cancer (NSCLC) has ranged from 5-30%, depending on the population studied. Lung cancer patients with tumor EGFR activating mutations have a more favorable prognosis than those without. With regard to second-line tyrosine kinase inhibitors (TKIs) following platinum-based chemotherapy, its tumor response rate was less than first-line TKIs in patients with EGFR mutations. The change of EGFR mutation status during disease course may partially explain the difference in the predictive value of EGFR mutation between first- and second-line TKIs treatment. First-line chemotherapy may have influence on status of EGFR mutations, and thus, EGFR mutation status collected from the initial specimens for diagnosis might be inadequate for predicting efficacy of EGFR-TKI treatment after first-line chemotherapy. Intratumoral heterogeneity in the initial single tumor biopsy specimen could also lead to misinterpretation of the tumor EGFR mutation status and difficulty in making precise treatment decision. Many investigators used plasma EGFR mutation obtained from peripheral blood samples to represent the post-chemotherapy EGFR mutation status. However, many studies revealed that plasma EGFR mutation could not completely represent EGFR mutation status in the tumor tissue. There could be many reasons for the change of EGFR mutation status after chemotherapy. Influence of chemotherapy on EGFR mutation status may be one of the explanations for this phenomenon. Intratumoral heterogeneity also plays an important role in diversity of tumor EGFR mutation status. Further studies will be necessary to explain the mechanisms of chemotherapy-induced EGFR mutation change.

Tumour tissue sampling for lung cancer management in the era of personalised therapy: what is good enough for molecular testing?

In the era of personalised cancer therapy, the demand for molecular profiling of the patient's tumour is steadily increasing. In advanced nonsmall cell lung cancer (NSCLC) patients, testing for epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements has become an essential component of clinical practice to select patients who are most likely to benefit from EGFR and ALK tyrosine kinase inhibitors, respectively. Furthermore, obtaining tissue specimens from recurrent or metastatic tumours or from patients who develop resistance to initial effective therapies are essential for our understanding of the molecular basis of tumour progression and development of drug resistance. Therefore, the sampling of tumour tissue that is representative and is adequate in quantity and quality for pathological diagnosis and genomic profiling is crucial. In this review, we will discuss factors that should be considered in obtaining and processing biopsy specimens to enable routine molecular analysis in NSCLC patients.

Intratumoral distribution of EGFR mutations and copy number in metastatic lung cancer, what impact on the initial molecular diagnosis?

BACKGROUND

Activating epidermal growth factor receptor (EGFR) mutations characterize a subgroup of non-small-cell lung cancer that benefit from first line EGFR tyrosine kinase inhibitors (EGFR-TKI). However, the existence of polyclonal cell populations may hinder personalized-medicine strategies as patients' screening often depends upon a single tumor-biopsy sample. The purpose of this study is to clarify and to validate in clinical testing conditions the accuracy of EGFR genotyping using different tumor sites and various types of samples (transthoracic, surgical or endoscopic biopsies and cytology specimens).

METHODS

We conducted a retrospective review of 357 consecutive patients addressed for EGFR mutation screening in accordance with the directive of the European Medicines Agency (stage IV NSCLC). Fifty-seven samples were EGFR mutated and 40 had adequate tumor specimens for analysis on multiple spatially separated sites. Ten wild type samples were also analyzed. A total of 153 and 39 tumor fragments, from mutated and non-mutated cases respectively, were generated to analyze tumor heterogeneity or primary-metastatic discordances. After histological review of all fragments, EGFR genotyping was assessed using the routine diagnostic tools: fragment analysis for insertions and deletions and allele specific TaqMan probes for point mutations. EGFR copy number (CN) was evaluated by qPCR using TaqMan probes.

RESULTS

The identification of EGFR mutations was independent of localization within primary tumor, of specimen type and consistent between primary and metastases. At the opposite, for half of the samples, tumor loci showed different EGFR copy number that may affect mutation detection cut-off.

CONCLUSIONS

This is the largest series reporting multiple EGFR testing in Caucasians. It validates the accuracy of EGFR mutation screening from single tumor-biopsy samples before first line EGFR-TKI. The unpredictable variability in EGFR CN and therefore in EGFR wild type/mutant allelic ratio justifies the implementation of sensitive methods to identify patients with EGFR mutated tumors.

Mechanisms of acquired resistance to EGFR-tyrosine kinase inhibitor in Korean patients with lung cancer

BACKGROUND

Despite an initial good response to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI), resistance to treatment eventually develops. Although several resistance mechanisms have been discovered, little data exist regarding Asian patient populations.

METHODS

Among patients at a tertiary referral hospital in Korea who initially responded well to gefitinib and later acquired resistance to treatment, we selected those with enough tissues obtained before EGFR-TKI treatment and after the onset of resistance to examine mutations by mass spectrometric genotyping technology (Asan-Panel), MET amplification by fluorescence in situ hybridization (FISH), and analysis of AXL status, epithelial-to-mesenchymal transition (EMT) and neuroendocrine markers by immunohistochemistry.

RESULTS

Twenty-six patients were enrolled, all of whom were diagnosed with adenocarcinoma with EGFR mutations (19del: 16, L858R: 10) except one (squamous cell carcinoma with 19del). Secondary T790M mutation was detected in 11 subjects (42.3%) and four of these patients had other co-existing resistance mechanisms; increased AXL expression was observed in 5/26 patients (19.2%), MET gene amplification was noted in 3/26 (11.5%), and one patient acquired a mutation in the phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA) gene. None of the patients exhibited EMT; however, increased CD56 expression suggesting neuroendocrine differentiation was observed in two patients. Interestingly, conversion from L858R-mutant to wild-type EGFR occurred in one patient. Seven patients (26.9%) did not exhibit any known resistance mechanisms. Patients with a T790M mutation showed a more favorable prognosis.

CONCLUSION

The mechanisms and frequency of acquired EGFR-TKI resistance in Koreans are comparable to those observed in Western populations; however, more data regarding the mechanisms that drive EGFR-TKI resistance are necessary.

Analysis of intratumor heterogeneity of EGFR mutations in mixed type lung adenocarcinoma

BACKGROUND

Epidermal growth factor receptor mutations are predictive of the success of EGFR tyrosine kinase inhibitor treatment in patients with advanced non--small-cell lung cancer. As with other solid tumors, lung cancer is thought to be the result of an accumulation of genetic alterations after exposure to carcinogens. The aim of the present study was to clarify the relationship between multistep carcinogenesis and the accumulation of EGFR mutations.

PATIENTS AND METHODS

The intratumor heterogeneity of EGFR mutations was analyzed in 38 patients with resected mixed-type lung adenocarcinoma according to histological patterns, and the clinical features of the patients harboring intratumor heterogeneity of EGFR mutations were evaluated.

RESULTS

Intratumor heterogeneity of EGFR mutations was detected in 9 of 38 tumors. EGFR mutations were more common in the bronchioloalveolar (lepidic) carcinoma pattern than in the papillary and acinar patterns, although this difference was not significant. However, there was a significant correlation between intratumor heterogeneity of EGFR mutations and smoking history (P < .043).

CONCLUSION

Intratumor heterogeneity of EGFR mutations correlates with the distribution of histological subtype in mixed type adenocarcinoma and is associated with smoking history.