Non-Small Cell Lung Cancer Testing on Reference Specimens: An Italian Multicenter Experience.

INTRODUCTION: Biomarker testing is mandatory for the clinical management of patients with advanced non-small cell lung cancer (NSCLC). Myriads of technical platforms are now available for biomarker analysis with differences in terms of multiplexing capability, analytical sensitivity, and turnaround time (TAT). We evaluated the technical performance of the diagnostic workflows of 24 representative Italian institutions performing molecular tests on a series of artificial reference specimens built to mimic routine diagnostic samples. METHODS: Sample sets of eight slides from cell blocks of artificial reference specimens harboring exon 19 EGFR (epidermal growth factor receptor) p.E746_AT50del, exon 2 KRAS (Kirsten rat sarcoma viral oncogene homologue) p.G12C, ROS1 (c-ros oncogene 1)-unknown gene fusion, and MET (MET proto-oncogene, receptor tyrosine kinase) Δ exon 14 skipping were distributed to each participating institution. Two independent cell block specimens were validated by the University of Naples Federico II before shipment. Methodological and molecular data from reference specimens were annotated. RESULTS: Overall, a median DNA concentration of 3.3 ng/µL (range 0.1-10.0 ng/µL) and 13.4 ng/µL (range 2.0-45.8 ng/µL) were obtained with automated and manual technical procedures, respectively. RNA concentrations of 5.7 ng/µL (range 0.2-11.9 ng/µL) and 9.3 ng/µL (range 0.5-18.0 ng/µL) were also detected. KRAS exon 2 p.G12C, EGFR exon 19 p.E736_A750del hotspot mutations, and ROS1 aberrant transcripts were identified in all tested cases, whereas 15 out of 16 (93.7%) centers detected MET exon 14 skipping mutation. CONCLUSIONS: Optimized technical workflows are crucial in the decision-making strategy of patients with NSCLC. Artificial reference specimens enable optimization of diagnostic workflows for predictive molecular analysis in routine clinical practice.

DAX-1 Expression in Pediatric Rhabdomyosarcomas: Another Immunohistochemical Marker Useful in the Diagnosis of Translocation Positive Alveolar Rhabdomyosarcoma.

OBJECTIVES: The aim of this study was to investigate the expression of DAX-1 in a series of pediatric rhabdomyosarcomas (RMS) with known translocation and compare it to Ap2ß, known to be selectively expressed in ARMS. DESIGN: We revised a series of 71 alveolar rhabdomyosarcomas (ARMS), enrolled in the Italian Protocols RMS 79 and 96, and 23 embryonal rhabdomyosarcomas (ERMS) as controls. Before investigating Ap2ß and DAX-1, ARMS were reviewed and reclassified as 48 ARMS and 23 non-ARMS. RESULTS: Translocation positive ARMS showed a characteristic Ap2ß/DAX-1+ staining pattern in 78% of cases, while 76% of classic ERMS were negative for both. Ap2ß alone was positive in 3.9% of RMS lacking translocation, whereas DAX-1 alone was positive in 25.4%. Conversely, 9% and 6% of translocation positive ARMS were positive only for DAX-1 or Ap2ß, respectively. The 23 non-ARMS shared the same phenotype as ERMS but had a higher frequency of DAX-1 expression. CONCLUSIONS: DAX-1 is less specific than Ap2ß, however it is a sensitive marker for translocation positive ARMS and can be helpful in their diagnosis if used in combination with Ap2ß.

STAT3 pathway is activated in ALK-positive large B-cell lymphoma carrying SQSTM1-ALK rearrangement and provides a possible therapeutic target.

ALK-positive large B-cell lymphomas usually harbor clathrin (CLTC)-ALK rearrangement or, more rarely, nucleophosmin (NPM)-ALK fusion gene. Here we report a large B-cell lymphoma with a peculiar pattern of diffuse and cytoplasmic immunohistochemical staining and carrying sequestosome 1 (SQSTM1)-ALK rearrangement, identified by reverse transcription polymerase chain reaction analysis and Rapid Amplification of cDNA Ends analysis and confirmed by fluorescence in situ hybridization with specific dual-color fusion probes. The gene fusion product and the transcription factor STAT3 are both phosphorylated, and thereby the pathogenetic mechanism of this case shows important analogies with that of NPM-ALK and CLTC-ALK lymphomas, in which STAT3 plays a central role in the lymphomagenesis. Consequently, STAT3 inhibition provides a possible therapeutic target also for lymphomas with SQSTM1-ALK variant translocation.