HIGH- DOSE CHEMOTHERAPY WITH TRANSPLANTATION OF AUTOLOGOUS HEMATOPOIETIC STEM CELLS IN THE FIRST LINE OF FOLLICULAR LYMPHOMA THERAPY

Introduction. The follicular lymphoma (FL) is the most common indolent lymphatic tumor with high sensitivity to immunochemotherapy un most cases. Although overall survival (OS) is generally long, the disease is characterized by multiple relapses. Highdose chemotherapy (HDCT) with transplantation of autologous hematopoietic stem cells (auto-HSCT) is used for recurrent FL. Aim: to evaluate the efficacy and safety of HDCT with aHSCT in the first line of FL therapy; identify risk factors for disease progression and refractoriness. Material and methods. A prospective single-center study (conducted from May 2015 to January 2023) included 35 patients aged 18- 65 years (median 43) with PL 1-3A grade t(14;18)+ with stages III-IV or stage II with bulky, having at least one criterion for the need to start therapy (according to GELF). Patients were treated according to the FL-2015 protocol: 4 R-CHOP, 2 R- DHAP and BeEAM with auto- HSCT. The primary endpoint was the rate of overall response (OR) and/or complete remission (CR) at the end of chemotherapy. Secondary end points were 3-year survival rates: OS, relapse-free survival (RFS), progression-free survival (PFS), and event-free survival (EFS). Minimal residual disease (MRD) in blood and/or bone marrow was assessed by PCR based on immunoglobulin heavy chain (IGH) gene rearrangements and/or BCL2::IGH rearrangements. Statistical analysis (by intent to treat) was performed on January 12, 2023. Results. 86 % of patients had stage IV tumor and 79 % had 3-5 FLIPI factors. After the end of treatment, OR and PR were 90 % and 90 %, the incidence of POD24 was 3 %. After the end of induction (4 courses of R-CHOP), MRD-negativity was achieved in 77 % and 53 % of patients as determined by PCR-IGH and BCL2::IGH. After the full completion of the FL-2015 protocol, MRD was not detected in 96 % of patients (according to PCR-IGH). Three-year overall survival, disease-free survival, progression-free survival and event-free survival were respectively: 90 %, 90 %, 95 % and 85 % (with the same standard error of 9 %) at a median follow-up (by inverse Kaplan- Meier estimate) of 19 months (range: from 1 to 91 months) There were no deaths due to early toxicity within 100 days of auto- HSCT. Prognostically unfavorable independent statistically significant (. < 0.01; Wald test; hazard ratio > 1) predictors of progression and refractoriness according to the results of multivariate analysis using the Fine-Grey competing risk model (. = 0.052 for the model) were: bone marrow disease, ECOG high risk, patient age > 50 years, stage 4 disease, elevated serum lactate dehydrogenase and B-symptoms. Conclusion. The use of HDCT with auto-HSCT in the first line in patients with FL is highly effective and can significantly reduce the incidence of POD24 and early mortality from the tumor. The study is ongoing.