Rapid EGFR evaluation from used H&E, IHC and FISH diagnostic slides with the Idylla platform.

AIMS: Diagnostic tumour samples are mandatory for morphologic and molecular diagnosis of non-small cell lung cancer (NSCLC) to establish the best therapeutic approach. In the presence of small tumour tissue sample, the pathologist needs to make responsible choices to achieve a correct diagnosis and save material for subsequent molecular evaluations. Nevertheless, in some instances, the diagnostic process can lead to tissue depletion. The automated Idylla epidermal growth factor receptor (EGFR) mutation test has been developed to rapidly process formalin-fixed paraffin-embedded (FFPE) pathologic material, without previous DNA extraction. This study aimed to test whether this platform is suitable for the reuse of H&E, immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH) diagnostic slides. METHODS: A training set of 19 FFPE tissues with known EGFR status was revaluated on H&E slides. Fourteen of them were also tested using IHC and FISH treated specimens. An additional series of 25 H&E, IHC or FISH slides of NSCLC cases tested for EGFR mutation at an external institution was blindly assessed as a validation cohort. RESULTS: Combining the two sets, 32 of 32 classical ex19dels and p.L858R were correctly identified. Three uncommon mutations (p.G719X, p.L861Q and ex20ins) were also detected. Four discrepancies were related to rare ex19del/ins not included in the Idylla list of detectable mutations. Two p.T790M variants were missed on one FFPE and two H&E slides but were detected using IHC and FISH sections from the same FFPE blocks. CONCLUSIONS: The Idylla EGFR mutation test is highly reliable using differently treated tumour specimens and should be validated in larger studies.

Intrapatient Molecular and Histologic Heterogeneity After First-generation or Second-generation TKI Therapy of NSCLC Patients: Potential Clinical Impact on Subsequent third-generation TKI Treatment.

OBJECTIVES: The discovery of tyrosine kinase inhibitors (TKI) has remarkably improved the clinical course of patients with non-small cell lung cancer driven by Epidermal Growth Factor Receptor (EGFR) mutations. However, virtually in all cases, the disease resurfaces in a TKI-resistant form that is mainly linked to an acquired EGFR-T790M mutation, a MET amplification, or small cell lung cancer (SCLC) transformation. Third-generation TKIs are able to block tumor growth through an irreversible binding to the T790M-mutated receptor. Such new treatments require the diagnostic analysis of new pathologic tissue or a liquid biopsy to detect the presence of the T790M mutation. MATERIALS AND METHODS: Pre-TKI and post-TKI biopsies from 27 patients with an activating EGFR mutation were collected and analyzed for EGFR-T790M mutation, MET amplification, and SCLC transformation. RESULTS: The T790M mutation was found in 16 patients (59%) whereas MET gene amplification was found in 2 (10.5%) of 19 evaluated cases. The histologic transformation from adenocarcinoma (ADC) to SCLC was identified in 3 patients (11%). In one of them reversal from SCLC back to adenocarcinoma was observed. One patient had the T790M mutation concordantly detected in 2 synchronous lesions whereas another patient showed T790M positivity only in one of 2 specimens. In 4 patients longitudinal biopsies revealed T790M gains and losses not always according to biological expectations. CONCLUSIONS: Intrapatient molecular or histologic heterogeneity may be frequently found during routine treatment of non-small cell lung cancer patients. This biological aspect may have profound repercussions on subsequent therapeutic decisions, and therefore requires in-depth investigation.

The synchronous occurrence of squamous cell carcinoma and gastrointestinal stromal tumor (GIST) at esophageal site.

BACKGROUND: Esophageal squamous cell carcinoma is a relative common malignancy with a very poor prognosis, even adopting an integrated and multidisciplinary approach. According to the literature, gastrointestinal stromal tumors (GISTs) rarely originate from the esophagus. Moreover there are not reports of synchronous occurrence of squamous cell carcinoma and GIST at esophageal site. CASE PRESENTATION: We describe a case of a 74 year old patient who underwent surgery for squamous cell carcinoma of the lower third of the esophagus with an incidental pathologic diagnosis of a concomitant GIST in the thoracic tract. CONCLUSION: In literature there is no evidence of concomitant squamous carcinoma and GIST of the thoracic esophagus, even if esophageal GISTs are sometimes described. The occasional finding of this neoplastic lesion underlines the importance of a carefully pathological diagnosis for its identification. Surgery, followed by a multidisciplinary approach remains the first-line treatment in both squamous and stromal neoplasm.