PS1084 AUTOLOGOUS STEM CELL TRANSPLANT IN DIFFUSE LARGE B CELL LYMPHOMA: SIMILAR OUTCOMES AFTER BEAM AND FEAM CONDITIONING REGIMENS

Background: Primary mediastinal (thymic) large B-cell lymphoma (PMBCL) is a unique type of non-Hodgkin lymphoma arising from a putative thymic medulla B cell. PMBCL constitutes 6–10% of all large B-cell lymphomas, occurring more often in young females and characterized by a locally invasive anterior mediastinal bulky mass. Efficacy of the first-line treatment and its outcome are critical in the management of patients with PMBCL. The choice of chemotherapy regimen as well as the need for radiotherapy (RT) consolidation are still matters of debate. Aims: The purpose of our study is evaluated outcomes and toxicity of intensive chemotherapy regimens with or without radiotherapy. Methods: 91 patients with PMBCL treated in N.N. Blokhin National Medical Scientific Oncology Center during 2004–2017 were included in the study. More than a half were women (58 %). Median age was 30 years (17 to 59 years). Most patients had locally advanced tumor growth in anterior upper mediastinum with involvement of the chest: I-IIE stages were diagnosed in 60 (66%). The most frequent of the extranodal zones was pulmonary involvement - 61 patients (67%). In the descending sequence, the remaining localizations followed: soft tissue of thorax was in 20 (22%), bones 6 (6,6%), liver 5 (5,5%), kidneys - 5 (5.5%), adrenal glands 4 (4,4%), gastrointestinal tract 4 (4,4%), thyroid - 4 (4,4%), other organs - 3 (3,3%). Bone marrow involvement was not found in any of the cases. All patients received intensive chemotherapy regimens as initial treatment: MACOP-B+/-R 55 patients (60%), R - DAEPOCH- 36 patients (40%). Radiation therapy to the mediastinum with overall dose of 30–36 Gy received 72 (79%) patients. Results: With a median follow-up of 37 months, the estimated 3-year progression-free survival (PFS) was 84 % and overall survival (OS) was 92 %. The 3-year PFS was 79% (MACOP-B+/-R) and 91% (R-DAEPOCH) respectively, OS was 88% and 97%. There was no significant difference between the PFS after MACOP-B+/-R and R-DAEPOCH regimens (p = 0,09) and OS (p = 0,1). 89% of patients had various complications. Grade 3–4 hematological toxicity occurred in 61 pts: MACOP-B+/-R 26 (43%) vs R-DAEPOCH 35 (57%) (p = 0.0001). Non hematological adverse events were seen in 21 pts: 14(67%) vs 7(33%) (p = 0.4). Infections of varying severity were observed in 59 pts 41 (69%) vs 18 (31%) (p = 0.01). Pneumonia, hypersensitivity pneumonitis after combined treatment was significantly more frequently recorded in patients receiving MACOP-B +/-R (26.8%) compared with 3.6% in R-DAEPOCH group (p = 0.02). Adverse pulmonary effects in MACOP-B +/-R group possibly related to the bleomycin administration. Glucocorticoid-induced osteonecrosis of the femoral head was detected in 3 (5,4%) cases after MACOP-B+/-R treatment. Summary/Conclusion: The efficacy of the initial treatment appears to be crucial to long-term survival rates of patients with PMBCL. Intensive chemotherapy regimens MACOP-B +/-R, R-DAEPOCH demonstrate high efficacy. MACOP-B +/-R treatment is inferior to R-DAEPOCH in toxicity (bleomycin-related pulmonary toxicity, glucocorticoid-induced osteonecrosis).