(P 245) MUTATIONAL STATUS OF CHONDROSARCOMA BASED ON TARGETED NEXT-GENERATION SEQUENCING ANALYSIS

Co-Author(s)

Agnieszka E. Zając, MSc

PhD student
Department of Soft Tissue/Bone Sarcoma and Melanoma, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
Warsaw, Mazowieckie, Poland
JP

Jakub Piątkowski, PhD

Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
Warsaw, Mazowieckie, Poland
PG

Paweł Golik, PhD

Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland & Institute of Biochemistry and Biophysics Polish Academy of Science, Warsaw, Poland
Warsaw, Mazowieckie, Poland
PT

Pawel Teterycz, MD PhD

Department of Soft Tissue/Bone Sarcoma and Melanoma, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
Warsaw, Mazowieckie, Poland
AS

Anna Szumera-Ciećkiewicz, MD, PhD

Department of Pathology and Laboratory Diagnostics, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland & Department of Diagnostic Hematology, Institute of Hematology and Transfusion Medicine, Warsaw, Poland
Warsaw, Mazowieckie, Poland
AT

Andrzej Tysarowski, PhD

Cancer Molecular and Genetic Diagnostics Laboratory, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
Warsaw, Mazowieckie, Poland
Emanuela Palmerini, MD

Consultant, Medical Oncologist
IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
Bologna, Emilia-Romagna, Italy
Marco Gambarotti, MD

Medical Doctor
Department of Pathology, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
Bologna, Emilia-Romagna, Italy
GF

Giorgio Frega, MD

Osteoncology, Bone and Soft Tissue Sarcomas and Innovative Therapies Unit IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
Bologna, Emilia-Romagna, Italy
MP

Michela Pierini, PhD

Osteoncology, Bone and Soft Tissue Sarcomas and Innovative Therapies Unit IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
Bologna, Emilia-Romagna, Italy
AR

Alberto Righi, MD, PhD

Pathologist
Deapartment of Pathology, IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
Bologna, Emilia-Romagna, Italy
GM

Giovanna Magagnoli, MSc

Deapartment of Pathology, IRCCS, Istituto Ortopedico Rizzoli, Bologna, Italy
Bologna, Emilia-Romagna, Italy
AD

Aurélie Dutour, PhD

CRCL, University Claude Bernard Lyon 1, Lyon, France
Lyon, Auvergne, France
MJ

Myriam Jean-Denis, PhD

Department of Biopathology, CLCC Léon Bérard, Lyon University, Lyon, France & CRCL, University Claude Bernard Lyon 1, Lyon, France
Lyon, Auvergne, France
Toni Ibrahim, BSc, MD, PhD

BSc, MSc ,MD, PhD
Osteoncology, Bone and Soft Tissue Sarcomas and Innovative Therapies Unit, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
Bologna, Emilia-Romagna, Italy
Jean-Yves Blay, MD, PhD (he/him/his)

Professor of Medicine,
Centre Léon Bérard and Université Claude Bernard, Lyon, France
Lyon, Auvergne, France

Author(s)

Anna M. Czarnecka, MD PhD (she/her/hers)

Professor
Department of Soft Tissue/Bone Sarcoma and Melanoma, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
Warsaw, Mazowieckie, Poland

Co-Author(s)

Piotr Rutkowski, MD, PhD

Head of Department of Soft Tissue/Bone Sarcoma and Melanoma, Professor of Surgical Oncology
Department of Soft Tissue/Bone Sarcoma and Melanoma; Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
Warsaw, Mazowieckie, Poland

Objective: The genetics of chondrosarcoma (ChS) is still poorly understood and only a few point mutations or chromosomal aberrations have been frequently reported in ChS. Among different ChS subtypes, the most common (even 60% of cases) mutations are IDH1/IDH2 (p.Arg132/ p.Arg172). Other frequent occurred in TP53, COL2A1, EXT/EXT2, MDM2, and CDKN2A genes. The genetic background and role of particular mutations in ChS progression and individual subtype development are still unknown. The aim of this study was to identify potentially pathogenic mutations in different subtypes of ChS.

Methods: In the study 24 patients (female/male ratio: 1/2, median age: 46,5 with range 21-88 years; subtypes: 7 G1, 3 G2, 9 G3, 4 dedifferentiated, 1 mesenchymal) with diagnosed primary ChS between 2011-2019, were enrolled. All patients were radically treated by surgery, except the mesenchymal case, which was treated additionally with adjuvant radiotherapy (stereotactic body radiation therapy, SRBT). DNA was isolated from formalin-fixed paraffin-embedded (FFPE) tissue from primary tumor radical surgery. Mutational signatures and tumor mutational burden (TMB) results were obtained by next-generation sequencing of 409 genes. Additionally, microsatellite instability (MSI) analysis was analyzed.

Results: The average TMB level was around 4 mutations/Mb and none of the patients had MSI found. The most frequently mutated genes were those related to proliferation and survival of the cell, including the PI3K-AKT and RAS-RAF-MEK pathways (i.a. TAF1, HNF1A, EPHB1, FLT3), and also genes involved in chromatin remodeling process (IDH1, IDH2, ARID1A). IDH1/IDH2 (Arg132/Arg172 mutations were identified in 33% of all cases, and they were involved in higher malignancy ChS subtypes (G2, G3, and dedifferentiated). The occurrence of ARID1A (12% of all cases) was also indicated in G2 and G3 ChS. Moreover, in 8% of cases PTCH1 mutations were detected, and they occurred only in the dedifferentiated and G3 subtypes of ChS, whereas mutations in SRC, PIK3CA, and MTOR genes were observed only in the mesenchymal subtype. In addition, TP53 and BCL2 mutations were identified in G3 and dedifferentiated ChS (12% of all cases).

Conclusion: Mutational status analysis suggests that the pathogenesis of high-grade ChS and progression of diseases may be related to tumor growth and cell proliferation (PI3K-AKT-mTOR, RAS-RAF-MEK-ERK), regulation of cell cycle, and apoptosis (p53 signaling), and chondrocyte differentiation (Hedgehog pathway) signaling pathways. Moreover, methylation of histones may play also an important role in high-grade ChS, but not in the mesenchymal subtype.