Reference standards for gene fusion molecular assays on cytological samples: an international validation study

Nom de la revue
Journal of Clinical Pathology
Umberto Malapelle, Francesco Pepe, Pasquale Pisapia, Annalisa Altimari, Claudio Bellevicine, Hans Brunnström, Rossella Bruno, Reinhard Büttner, Luis Cirnes, Carlos E De Andrea, Dario de Biase, Catherine I Dumur, Kajsa Ericson Lindquist, Gabriella Fontanini, Eugenio Gautiero, David Gentien, Paul Hofman, Veronique Hofman, Antonino Iaccarino, Maria Dolores Lozano, Clara Mayo-de-Las-Casas, Sabine Merkelbach-Bruse, Fabio Pagni, Ruth Roman, Fernando C Schmitt, Janna Siemanowski, Sinchita Roy-Chowdhuri, Giovanni Tallini, Francesc Tresserra, Sara Vander Borght, Philippe Vielh, Elena Vigliar, Giulia Anna Carmen Vita, Birgit Weynand, Rafael Rosell, Miguel Angel Molina Vila, Giancarlo Troncone

AimsGene fusions assays are key for personalised treatments of advanced human cancers. Their implementation on cytological material requires a preliminary validation that may make use of cell line slides mimicking cytological samples. In this international multi-institutional study, gene fusion reference standards were developed and validated.MethodsCell lines harbouringEML4(13)–ALK(20) andSLC34A2(4)–ROS1(32) gene fusions were adopted to prepare reference standards. Eight laboratories (five adopting amplicon-based and three hybridisation-based platforms) received, at different dilution points two sets of slides (slide A 50.0%, slide B 25.0%, slide C 12.5% and slide D wild type) stained by Papanicolaou (Pap) and May Grunwald Giemsa (MGG). Analysis was carried out on a total of 64 slides.ResultsFour (50.0%) out of eight laboratories reported results on all slides and dilution points. While 12 (37.5%) out of 32 MGG slides were inadequate, 27 (84.4%) out of 32 Pap slides produced libraries adequate for variant calling. The laboratories using hybridisation-based platforms showed the highest rate of inadequate results (13/24 slides, 54.2%). Conversely, only 10.0% (4/40 slides) of inadequate results were reported by laboratories adopting amplicon-based platforms.ConclusionsReference standards in cytological format yield better results when Pap staining and processed by amplicon-based assays. Further investigation is required to optimise these standards for MGG stained cells and for hybridisation-based approaches.