Pb2081: cytogenetics of multiple myeloma in morocco

Topic: 13. Myeloma and other monoclonal gammopathies - Biology & Translational Research Background: Cytogenetics have a major prognostic implication in multiple myeloma, especially particular abnormalities, such as del 17p, which is currently the most powerful unfavorable prognostic factor. There are little data on the cytogenetic aspects of multiple myeloma in Morocco. Aims: The aim of this study is to describe the prevalence of cytogenetic abnormalities associated with multiple myeloma in our population. Methods: We enrolled patients with multiple myeloma from 2009 to 2023 at the Clinical Hematology Department of the Military Hospital of Rabat. Results: One hundred and ninety-six patients were included. The median age was 60 years [28 - 81]. Regarding the immunoglobulin (Ig) isotype distribution in our patients, IgG accounts for 52.9%, IgA for 15%, IgM and IgD for 0.5% each. Free light chain secretion accounts for respectively 15% and 14.4% for the lambda and kappa sub-type. 1.6% of patients had a non-secretory multiple myeloma. 44.9% had a stage 3 ISS. Data on cytogenetic abnormalities detected by fluorescence in situ hybridization (FISH) on purified CD138+ marrow plasma cells were available for 87 patients. Among these patients, 10.3% (9 patients) had a plasma cell poor sample that did not allow FISH to be performed (FISH failure), 20.7% (18 patients) had no abnormalities, and 28.7% (25 patients) did not benefit from the full panel due to a limited number of purified plasma cells after sorting (del(17p) and t(4;14) were prioritized, and the results came back negative). Cytogenetic abnormalities were found in 35 patients. Ten patients (28.6%) had the t(4;14) and was associated to gain/amp(1q21) in one patient. 7 patients (20%) had the del(17p). Of these, 3 patients presented del(17p) combined to gain/amp(1q21), gain/amp(1q21)/ del(4p)/ 14q32 rearrangement, and to t(11;14)/ trisomy 14/ trisomy 4 respectively. The gain/amp(1q21) was found in 10 patients (28.6%) and was associated to other abnormalities in 7 patients. Seven patients (20%) had the 14q32 rearrangement, 3 patients (8.6%) showed the t(11;14), 1 patient (2.8%) had the del(1p), and 9 patients (25.7%) presented with other abnormalities; del(13p), del(14q), del(4p), t(1;14), trisomy 14 and trisomy 4. The t(14;16) was not looked for in our patients. Therefore, 25 patients (71.4%) presented with high-risk cytogenetic abnormalities, and 10 patient (28.6%) with standard risk. The conventional cytogenetic was performed in 20.4% (40 patients), of which 65% (26 patients) had a normal karyotype, 5% (2 patients) had hyperdiploidy, and 5% (2 patients) had pseudo diploidy, which are standard-risk anomalies. 5% (2 patient) had hypodiploidy and 20% (8 patients) had a complex karyotype which are considered as high cytogenetic risk anomalies. Summary/Conclusion: Our results showed the preponderance of the t(4;14), and the predominance of the gain/amp(1q21) followed by the del(17p). A larger population study is needed to confirm the cytogenetics profile in Moroccan multiple myeloma patients. Keywords: Cytogenetics, High risk, Multiple myeloma, Cytogenetic abnormalities