Pb2085: epidemiological description and prognosis features of multiple myeloma in a tunisian haematology center

Topic: 13. Myeloma and other monoclonal gammopathies - Biology & Translational Research Background: Multiple myeloma (MM) is a haematological malignancy that is characterized by an uncontrolled growth of medullary monoclonal plasma cells with an overproduction of non-functional immunoglobins. MM diagnosis was revised in 2014 by IMWG guidelines. This actualization led to a paradigm shift in therapeutic approach. However, low survival rate and inevitable relapse still remain. Aims: This study, conducted from January 1, 2016 to September 30, 2021 described epidemiological, clinical and biological characteristics of a cohort of patients with MM followed by the largest Tunisian haematology center (Aziza Othmana Hospital, Tunis, Tunisia). Methods: All symptomatic subjects aged less than 70 years and who had received Bortezomib-Thalidomide and Dexamethasone-based chemotherapy (VTD) were included. MM diagnosis was retained in front of a 60% clonal plasma cell proliferation and/or a ratio of serum free light chains greater than 100 and/or presence of a focal lesion on Magnetic Resonance Imaging. We excluded all other monoclonal gammopathies (monoclonal gammopathy of undetermined meaning, Waldenstrom disease). Biochemical, haematological and cytogenetic features were assessed. VTD was started and an autograft (AG) was then practiced. Clinico-biological investigation was initially ensured every 3 months after AG. Progression has been confirmed by a 25% increase, either in monoclonal immunoglobulin or light free chains, high rates of calcemia (over than 2.65mmol/l) or a haemoglobin level falling by 2 g/dl. Survival rate was calculated using the Kaplan Mayer method. Student’s t-test and Rho coefficient of Spearman were used for comparison of means and ordinal variables. A significance level was retained for p or Fischer Index (FI) less than 0.05. Results: Sixty-two patients were included with a mean age of 53 ± 8.5 years and a sex ratio of 0.55. Among the CRAB criteria, anaemia was found in 80.6% of patients, hypercalcemia in 43.5% and renal failure in 16% with an average serum creatinine of 340 µmol/L. Mean beta-2-microglobulinlevel was 5.28mg/L ±3.75. The peak of monoclonal component was significantly correlated with marrow infiltration (p=0.013) and serum protein level (p<0.001). The translocation t (4.14) was detected in 8.1% of cases. Fifty-five patients (88.7%) received 4 cycles of VTD as induction treatment; 32.4% of them developed neurotoxicity signs (polyneuropathy). AG was performed for 39 patients (62.9%). Medium period between diagnosis and chemotherapy was 3.9 months ±1.9 (1-11 months). It was 10 months ±4 between diagnosis and AG and 7 months ± 2.5 between the beginning of the first VTD cure and AG. Twelve patients (19%) received a brief consolidation treatment and 14 (22%) had a maintenance treatment. Relapse was observed in 43.4% cases (39.6% with AG vs 66.7% without AG; FI= 0.57); mean delay was 26 months±14.6. Survival rate at 3 years was 78% in patients with AG. Poor prognostic factors were advanced age (p=0.002), high serum creatinine level (p = 0.029) and time between the start of VTD and AG (p = 0.034). Survival rate was also lower for patients who received less than 4 courses of VTD or who did not benefit from an AG. Summary/Conclusion: This 3-year survey highlighted the heterogeneity of clinical and biological aspects of MM and the importance of AG after intensive chemotherapy treatment. It also identified the main prognostic factors that should be included in the initial assessment to improve medical management and to ensure high survival rates. Keywords: Plasma cells, Multiple myeloma, Monoclonal gammopathy, Autograft