Circulating tumor DNA of classical Hodgkin lymphoma.

person Maria Cristina Pirosa Institute of Oncology Research, Bellinzona, Switzerland info_outline Maria Cristina Pirosa, Alessio Bruscaggin, Lodovico Terzi di Bergamo, Matin Salehi, Variera Spina, Katia Pini, Simone Bocchetta, Claudia Giordano, Gabriela Forestieri, Fabrizio Bergesio, Valter Gattei, Jan Maciej Zaucha, Stefan Hohaus, Armando Santoro, Carmelo Carlo-Stella, Gianluca Gaidano, Franco Cavalli, Emanuele Zucca, Luca Ceriani, Davide Rossi

Authors person Maria Cristina Pirosa Institute of Oncology Research, Bellinzona, Switzerland info_outline Maria Cristina Pirosa, Alessio Bruscaggin, Lodovico Terzi di Bergamo, Matin Salehi, Variera Spina, Katia Pini, Simone Bocchetta, Claudia Giordano, Gabriela Forestieri, Fabrizio Bergesio, Valter Gattei, Jan Maciej Zaucha, Stefan Hohaus, Armando Santoro, Carmelo Carlo-Stella, Gianluca Gaidano, Franco Cavalli, Emanuele Zucca, Luca Ceriani, Davide Rossi Organizations Institute of Oncology Research, Bellinzona, Switzerland, Aou Federico II, Napoli, Italy, AO S.Croce e Carle, Cuneo, Italy, Clinical and Experimental Onco Hematology Unit, Centro di Riferimento Oncologico, Aviano, Italy, Medical University of Gdansk, Laboratory of Translational Oncology, Gdansk, Poland, Gdynia, Poland, Fondazione Policlinico Universitario A. Gemelli, IRCCS; Univerità Cattolica del Sacro Cuore, Roma, Italy, IRCCS Humanitas Research Hospital, Rozzano, Italy, Humanitas Research Hospital (Italy), Rozzano, Italy, University of Eastern Piedmont, Novara, Italy, Institute of Oncology Research - IOR, Bellinzona, Switzerland, Institute of Oncology Research; Clinic of Hematology, Oncology Institute of Southern Switzerland, Ente Ospedaliero Cantonale; Faculty of Biomedical Science, Universita’ della Svizzera italiana; International Extranodal Lymphoma Study Group (IELSG), Bellinzona, Lugano, Switzerland, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona, Switzerland, Università Della Svizzera Italiana, Institute of Oncology Research, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland Abstract Disclosures Research Funding Other European Research Council (ERC) Consolidator Grant CLLCLONE, ID: 772051; Swiss Cancer Research Foundation, ID 3746, 4395, 4660, 5257, Bern, Switzerland; Swiss National Science Foundation, ID 320030_169670/1, 310030_192439, 320036_179318 Background: Classical Hodgkin lymphoma (cHL) is the most common lymphoma in young adults. The morphologic peculiarity that makes cHL unique are the few tumor cells surrounded by a polytypic inflammatory microenvironment. It is also the cancer with the highest sensitivity to immune checkpoint inhibitors. But why is it so immunogenic and how it escapes the immune control at the same time have only been partially elucidated. Although cure rates of cHL have constantly increased over the years there is still a high need for identification of biomarkers for more precise treatment decisions. The need for enriching tumor cells before assaying has limited cHL biological studies. Patients with cHL have significant amounts of circulating tumor DNA (ctDNA), suggesting an alternative approach for studying this enigmatic tumor. Methods: IOSI-EMA003 (NCT03280394) is a prospective, observational, multi-center study of adult patients with previously untreated cHL aiming at: i) identifying subgroups of patients with phenotype- and outcome-associated molecular signatures; ii) testing and validating baseline ctDNA load as a prognostic biomarker; iii) testing if ctDNA can be used for the early identification of chemoresistance. Blood samples were collected at staging and disease response assessment. PET scans were centrally and blindly reviewed. ctDNA was analyzed by using deep targeted and shallow whole genome sequencing to measure ctDNA load, capture mutations and profile ctDNA fragmentation patterns. The composition of the tumor microenvironment of cHL was probed by single cell RNA-seq. Results: A total of 215 patients were enrolled. Based on ctDNA fragmentation patterns reflecting chromatin accessibility in the regulatory region of germinal center (GC) B-cell genes, we segregated cHL into two subgroups that we named SNCD (for sub-nucleosomal cfDNA) and NCD (for nucleosomal cfDNA). We hypothesized that SNCD cHL stems from a cell that is closer to the GC B-cell differentiation stage than NCD cHL. SNCD cHL and NCD cHL differed in many aspects, including activation induced cytidine deaminase (AID)-hypermutation profile, neoantigen load, immune editing mechanism and response to chemotherapy and checkpoint inhibitors. Clinically, SNCD cHL displayed less sensitivity to both chemotherapy and anti-PD1 antibodies. Immune editing of SNCD cHL points loss of MHC-I, recruitment of Treg and upregulation of LAG3 as prominent immune checkpoint. High load of pre-treatment ctDNA nominated high-risk patients more accurately than clinico-radiological features. In addition, persistence of residual 18 FDG avid lesions and measurable ctDNA was a better proof of chemoresistance than the sole persistence of residual 18 FDG avid lesions. Conclusions: Our results provide a roadmap for cHL subtyping and molecular classification. We also propose ctDNA as a quantifiable and radiation-free biomarker to be used in clinical trials testing a more personalized treatment approach. Clinical trial information: NCT03280394.

Clinical