EGFR mutations and lung cancer da Cunha Santos, Gilda; Shepherd, Frances A; Tsao, Ming Sound
Annual review of pathology,
02/2011, Volume:
6
Journal Article
Peer reviewed
Open access
Epidermal growth factor receptor (EGFR) is a transmembrane protein with cytoplasmic kinase activity that transduces important growth factor signaling from the extracellular milieu to the cell. Given ...that more than 60% of non-small cell lung carcinomas (NSCLCs) express EGFR, EGFR has become an important therapeutic target for the treatment of these tumors. Inhibitors that target the kinase domain of EGFR have been developed and are clinically active. More importantly, such tyrosine kinase inhibitors (TKIs) are especially effective in patients whose tumors harbor activating mutations in the tyrosine kinase domain of the EGFR gene. More recent trials have suggested that for advanced NSCLC patients with EGFR mutant tumors, initial therapy with a TKI instead of chemotherapy may be the best choice of treatment. Therefore, mutation testing is mandatory to identify these patients, given that selection based only on clinico-pathologic characteristics is inadequate. We review the role of EGFR mutations in the diagnosis and management of NSCLC.
- Traditional methods for storing histologic and cytologic specimens for future use in molecular assays have consisted of either snap-freezing with cryopreservation or formalin-fixing, ...paraffin-embedding the samples. Although snap-freezing with cryopreservation is recommended for better preservation of nucleic acids, the infrastructure and space required for archiving impose challenges for high-volume pathology laboratories. Cost-effective, long-term storage at room temperature; relatively easy shipment; and standardized handling can be achieved with formalin-fixed, paraffin-embedded samples, but formalin fixation induces fragmentation and chemical modification of nucleic acids. Advances in next-generation sequencing platforms, coupled with an increase in diagnostic, prognostic, and predictive molecular biomarkers have created a demand for high-quality nucleic acids. To address issues of the quality of nucleic acid and logistics in sample acquisition, alternatives for specimen preservation and long-term storage have been described and include novel universal tissue fixatives, stabilizers, and technologies.
- To collect, retrieve, and review information from studies describing the use of nucleic acids recovered from cytologic/tissue specimens stored on Flinders Technology Associates (FTA, GE Whatman, Maidstone, Kent, United Kingdom) cards for downstream molecular applications.
- An electronic literature search in the PubMed (National Center for Biotechnology Information, Bethesda, Maryland) database allowed the selection of manuscripts addressing the use of FTA cards for storage of cytologic samples for molecular analysis. Only articles published in English were retrieved.
- The use of FTA cards is a versatile method for fostering multicenter, international collaborations and clinical trials that require centralized testing, long-distance shipment, and high-quality nucleic acids for molecular techniques. Studies with controlled temperature are required to test the quality of recovered RNA after long-term storage.
Objective The study objective was to compare endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) with mediastinoscopy for mediastinal lymph node staging of potentially ...resectable non–small cell lung cancer. Methods Patients with confirmed or suspected non–small cell lung cancer who required mediastinoscopy to determine suitability for lung cancer resection were entered into the trial. All patients underwent EBUS-TBNA followed by mediastinoscopy under general anesthesia. If both were negative for N2 or N3 disease, the patient underwent pulmonary resection and mediastinal lymphadenectomy. Results Between July 2006 and August 2010, 190 patients were registered in the study, 159 enrolled, and 153 were eligible for analysis. EBUS-TBNA and mediastinoscopy sampled an average of 3 and 4 lymph node stations per patient, respectively. The mean short axis of the lymph node biopsied by EBUS-TBNA was 6.9 ± 2.9 mm. The prevalence of N2/N3 disease was 35% (53/153). There was excellent agreement between EBUS-TBNA and mediastinoscopy for mediastinal staging in 136 patients (91%; Kappa, 0.8; 95% confidence interval, 0.7–0.9). Specificity and positive predictive value for both techniques were 100%. The sensitivity, negative predictive value, and diagnostic accuracy for mediastinal lymph node staging for EBUS-TBNA and mediastinoscopy were 81%, 91%, 93%, and 79%, 90%, 93%, respectively. No significant differences were found between EBUS-TBNA and mediastinoscopy in determining the true pathologic N stage (McNemar’s test, P = .78). There were no complications from EBUS-TBNA. Minor complications from mediastinoscopy were observed in 4 patients (2.6%). Conclusions EBUS-TBNA and mediastinoscopy achieve similar results for the mediastinal staging of lung cancer. As performed in this study, EBUS-TBNA can replace mediastinoscopy in patients with potentially resectable non–small cell lung cancer.
- Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has emerged as a very useful tool in the field of diagnostic respiratory cytology. Rapid on-site evaluation (ROSE) of ...EBUS-TBNA not only has the potential to improve diagnostic yield of the procedure but also to triage samples for predictive molecular testing to guide personalized treatments for lung cancer.
- To provide an overview of the current status of the literature regarding ROSE of EBUS-TBNA in the diagnosis of lung cancer.
- An electronic literature search in PubMed and Google databases was performed using the following key words: cytology, lung cancer, on-site evaluation, rapid on-site evaluation, and ROSE EBUS-TBNA. Only articles published in English were included in this review.
- Rapid on-site evaluation can ensure that the targeted lesion is being sampled and can enable appropriate specimen triage. If available, it should be used with EBUS-TBNA in the diagnosis of lung cancer because it can minimize repeat procedures for additional desired testing (ie, molecular studies). Some studies have shown that ROSE does not adversely affect the number of aspirations, total procedure time of EBUS-TBNA, or the rate of postprocedure complications; it is also helpful in providing a preliminary diagnosis that can reduce the number of additional invasive procedures, such as mediastinoscopy. As EBUS technology continues to evolve, our knowledge of the role of ROSE in EBUS-TBNA for the diagnosis of lung cancer will also continue to grow and evolve.
To evaluate the effect of KRAS and epidermal growth factor receptor (EGFR) genotype on the response to erlotinib treatment in the BR.21, placebo-controlled trial.
We analyzed 206 tumors for KRAS ...mutation, 204 tumors for EGFR mutation, and 159 tumors for EGFR gene copy by fluorescent in situ hybridization (FISH). We reanalyzed EGFR deletion/mutation using two highly sensitive techniques that detect abnormalities in samples with 5% to 10% tumor cellularity. KRAS mutation was analyzed by direct sequencing.
Thirty patients (15%) had KRAS mutations, 34 (17%) had EGFR exon 19 deletion or exon 21 L858R mutations, and 61 (38%) had high EGFR gene copy (FISH positive). Response rates were 10% for wild-type and 5% for mutant KRAS (P = .69), 7% for wild-type and 27% for mutant EGFR (P = .03), and 5% for EGFR FISH-negative and 21% for FISH-positive patients (P = .02). Significant survival benefit from erlotinib therapy was observed for patients with wild-type KRAS (hazard ratio HR = 0.69, P = .03) and EGFR FISH positivity (HR = 0.43, P = .004) but not for patients with mutant KRAS (HR = 1.67, P = .31), wild-type EGFR (HR = 0.74, P = .09), mutant EGFR (HR = 0.55, P = .12), and EGFR FISH negativity (HR = 0.80, P = .35). In multivariate analysis, only EGFR FISH-positive status was prognostic for poorer survival (P = .025) and predictive of differential survival benefit from erlotinib (P = .005).
EGFR mutations and high copy number are predictive of response to erlotinib. EGFR FISH is the strongest prognostic marker and a significant predictive marker of differential survival benefit from erlotinib.
Erlotinib prolonged survival of unselected patients with advanced non-small-cell lung cancer (NSCLC) who were not eligible for further chemotherapy, and two phase II studies suggested it might be an ...alternative to first-line chemotherapy. A randomized phase III trial was designed to test whether first-line erlotinib followed at progression by cisplatin-gemcitabine was not inferior in terms of survival to the standard inverse sequence.
Patients with stage IIIB (with pleural effusion or supraclavicular nodes) to IV NSCLC and performance status of 0 to 1 were eligible. With a 95% CI upper limit of 1.25 for the hazard ratio (HR) for death, 80% power, a one-sided α = .025, and two interim analyses, a sample size of 900 patients was planned.
At the first planned interim analysis with half the events, the inferiority boundary was crossed, and the Independent Data Monitoring Committee recommended early termination of the study. Seven hundred sixty patients (median age, 62 years; range, 27 to 81 years) had been randomly assigned. Baseline characteristics were balanced between study arms. As of June 1, 2011, median follow-up was 24.3 months, and 536 deaths were recorded (263 in the standard treatment arm and 273 in the experimental arm). Median survival was 11.6 months (95% CI, 10.2 to 13.3 months) in the standard arm and 8.7 months (95% CI, 7.4 to 10.5 months) in the experimental arm. Adjusted HR of death in the experimental arm was 1.24 (95% CI, 1.04 to 1.47). There was no heterogeneity across sex, smoking habit, histotype, and epidermal growth factor receptor (EGFR) mutation.
In unselected patients with advanced NSCLC, first-line erlotinib followed at progression by cisplatin-gemcitabine was significantly inferior in terms of overall survival compared with the standard sequence of first-line chemotherapy followed by erlotinib.
Background
The presence of anaplastic lymphoma kinase (ALK) rearrangement predicts response to ALK tyrosine kinase inhibitor (TKI) therapy. Fluorescence in situ hybridization (FISH) was the initial ...reference standard to detect ALK rearrangement, but immunohistochemistry (IHC) using D5F3 has gained acceptance as an alternative diagnostic method. ALK IHC assays using other ALK antibodies have also been used as screening methods, but data supporting their utility as diagnostic tests have not been widely reported.
Methods
Data from reflexive clinical ALK IHC test using the 5A4 clone concurrent with epidermal growth factor receptor (EGFR) mutation testing were analyzed. ALK IHC results were reported as negative (−), equivocal, or positive (+), with equivocal or positive staining validated by FISH break‐apart probe testing. Treatment outcomes were reviewed for ALK IHC+ patients.
Results
Between 2012 and 2015, 146 (2.5%) cases were reported as ALK IHC+, 188 (3.2%) were reported as equivocal, and 5624 (94.4%) were reported as ALK IHC−. Of the ALK IHC+ cases, 131/143(91.6%) were ALK FISH+. Excluding 6 cases in which FISH was inconclusive or not performed, the positive predictive value was 95.6%, and the negative predictive value was 100%. Most specimens (n = 5352 89.6%) were also successfully tested for EGFR. Clinical responses to ALK TKIs were noted in 49 ALK IHC+ patients, with a median progression‐free survival of 9.9 months.
Conclusions
ALK 5A4 IHC can serve as a robust diagnostic test for ALK‐rearranged lung cancer and is associated with treatment response and survival. Optimized tissue allocation resulted in high success rates of combined reflex EGFR and ALK testing.
A large dataset derived from routine clinical reflex anaplastic lymphoma kinase (ALK) testing performed at a Canadian reference lung biomarker testing center demonstrates that the ALK 5A4 laboratory‐developed test is effective as both a screening assay and diagnostic assay to detect ALK fusion in lung cancer patient samples. The testing protocol also minimizes specimen tissue wastage and allows for successful additional biomarker testing in a majority of samples.
A clinical trial that compared erlotinib with a placebo for non-small-cell lung cancer demonstrated a survival benefit for erlotinib. We used tumor-biopsy samples from participants in this trial to ...investigate whether responsiveness to erlotinib and its impact on survival were associated with expression by the tumor of epidermal growth factor receptor (EGFR) and EGFR gene amplification and mutations.
EGFR expression was evaluated immunohistochemically in non-small-cell lung cancer specimens from 325 of 731 patients in the trial; 197 samples were analyzed for EGFR mutations; and 221 samples were analyzed for the number of EGFR genes.
In univariate analyses, survival was longer in the erlotinib group than in the placebo group when EGFR was expressed (hazard ratio for death, 0.68; P=0.02) or there was a high number of copies of EGFR (hazard ratio, 0.44; P=0.008). In multivariate analyses, adenocarcinoma (P=0.01), never having smoked (P<0.001), and expression of EGFR (P=0.03) were associated with an objective response. In multivariate analysis, survival after treatment with erlotinib was not influenced by the status of EGFR expression, the number of EGFR copies, or EGFR mutation.
Among patients with non-small-cell lung cancer who receive erlotinib, the presence of an EGFR mutation may increase responsiveness to the agent, but it is not indicative of a survival benefit.
The advent of targeted therapy in lung cancer has heralded a paradigm shift in the practice of cytopathology with the need for accurately subtyping lung carcinoma, as well as providing adequate ...material for molecular studies, to help guide clinical and therapeutic decisions. The variety and versatility of cytologic-specimen preparations offer significant advantages to molecular testing; however, they frequently remain underused. Therefore, evaluating the utility and adequacy of cytologic specimens is critical, not only from a lung cancer diagnosis standpoint but also for the myriad ancillary studies that are necessary to provide appropriate clinical management. A large fraction of lung cancers are diagnosed by aspiration or exfoliative cytology specimens, and thus, optimizing strategies to triage and best use the tissue for diagnosis and biomarker studies forms a critical component of lung cancer management. This review focuses on the opportunities and challenges of using cytologic specimens for molecular diagnosis of lung cancer and the role of cytopathology in the molecular era.
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