Abstract LB-268: Detection of TP53 clonal mutations in PAP test collected up to six years prior to high-grade serous epithelial ovarian cancer diagnosis
Authors: Pesenti Chiara , Paracchini Lara , Marchette Martina Delle , Beltrame Luca , Bianchi Tommaso , Grassi Tommaso , Buda Alessandro , Landoni Fabio , Ceppi Lorenzo , Bosetti Cristina , Paderno Maria Chiara , Adorni Marco , Vicini Debora , Perego Patrizia , Leone Biagio Eugenio , Marchini Sergio , Fruscio Robert , D'Incalci Maurizio 
Published: September 2020

Abstract
Background: The low five-years survival rate of High Grade Serous Epithelial Ovarian Cancer (HGS-EOC) is mainly related to late diagnosis. The anticipation of diagnosis constitutes a crucial step to increase the curability of this disease.
Aim: This study explores an innovative potential HGS-EOC screening approach exploiting PAP tests routinely executed for cervical cancer surveillance and the presence of TP53 clonal alterations in almost all HGS-EOCs. Indeed, it investigates the possibility to detect, in DNA purified from PAP tests collected by patients years before the diagnosis, the clonal pathogenic TP53 variant identified in the matched primary tumor biopsy.
Study Design: This retrospective and longitudinal study was conducted on 17 advanced HGS-EOC patients. Next Generation Sequencing (NGS) was used to identify TP53 clonal mutations in tumor tissue. The presence of these TP53 variants was then assessed by the droplet digital PCR (ddPCR) in DNA purified from all available patients' PAP tests executed up to almost six years before diagnosis.
Results: In each patient, one TP53 clonal somatic variant was identified by NGS in the primary tumor samples (Table 1). The presence of the TP53 variant was then investigated by ddPCR in matched Pap tests. In twelve out of 17 patients the TP53 variant was detectable in PAP tests collected within six months before diagnosis (T1) or earlier (T2, T3 and T4) (Table 1). For two patients (21561 and 21521) more PAP tests collected at different time before diagnosis (two/four and three/six years before diagnosis, respectively) were analyzed and the TP53 clonal variant was detected at all time points (Table 1).
Table 1:NGS and ddPCR resultsPatient IDTP53 mutationNGS tumor mutated %PAP test (months before surgery)T1(0-6)T2(7-24)T3(25-48)T4(≥49)Time intervalddPCR mutated %Time intervalddPCR mutated %Time intervalddPCR mutated %Time intervalddPCR mutated %21561c.818G&gt;A65.010.20.24--250.21490.2621585c.817C&gt;T40.94--11.30.21----21567c.281C&gt;A71.9830.07------21587c.469G&gt;T15.122ND------21586c.818G&gt;A79.73--19.30.15----21569c.574C&gt;T62.365.21.18------21624c.820G&gt;T86.72----37.50.0465.3ND21570c.844C&gt;T89.190.32.62------21627c.425_427del76.040.72.4------21640c.993+2T&gt;G70.68--8ND----21507c.1025G&gt;C91.23--9.20.06----21635c.844C&gt;T66.241.3ND------21549c. 393_395del54.06----31.2ND65.3ND21521c. 722 C&gt;G61.15----26.70.0567.30.0721654c.586 C&gt;T49.354.70.09------21665c. 393_395del45.34----37.6ND--21683c.602 T&gt;A33.42--18.50.06----ND Not Detected
Conclusion: This study demonstrates that non-invasive early molecular diagnosis of HGS-EOC is feasible through detection of TP53 clonal mutations in the DNA purified from PAP tests performed during cervical cancer screening. Further developments in highly sensitive molecular approaches could dramatically improve early diagnosis of HGS-EOC.
Citation Format: Chiara Pesenti, Lara Paracchini, Martina Delle Marchette, Luca Beltrame, Tommaso Bianchi, Tommaso Grassi, Alessandro Buda, Fabio Landoni, Lorenzo Ceppi, Cristina Bosetti, Maria Chiara Paderno, Marco Adorni, Debora Vicini, Patrizia Perego, Biagio Eugenio Leone, Sergio Marchini, Robert Fruscio, Maurizio D'Incalci. Detection of TP53 clonal mutations in PAP test collected up to six years prior to high-grade serous epithelial ovarian cancer diagnosis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-268.