Outcomes of Primary Mediastinal Large B-Cell Lymphoma: Insights from the Ukrainian Lymphoma Registry
Authors: Shokun Nazarii , Stepanishyna Yana , Tytorenko Iryna , Aleksyk Olena , Kadnikova Tetyana , Pastushenko Yan , Burtna Alevtyna , Rudyuk Timur , Shudrak Natalia , Moiseienko Katya , Skrypets Tetiana , Federico Massimo , Kryachok Iryna 
Published: December 2024

Introduction
Primary mediastinal large B-cell lymphoma (PMBCL) is a distinct subtype of diffuse large B-cell lymphoma, predominantly affecting young adults with a higher incidence in females PMBCL represents a focus of interest as a rare extranodal lymphoma subtype. . The Ukrainian Lymphoma Registry (ULR) collects data for better assessing the quality of care of patients in Ukraine.. This study presents an analysis of these patients, highlighting their demographic characteristics, disease distribution, and clinical outcomes.
Aim:
To analyze the results of treatment of patients with PMBCL collected prospectively in the Ukrainian Lymphoma Registry October from 2019 to June 2024.
Methods
Information on baseline clinical, disease characteristics, first-line treatment, response evaluation, and follow-up data was extracted from the ULR. Patients were treated according to the local standards. Response to treatment was assessed based on Cheeson 2007 and Lugano 2014 criteria. Descriptive statistics were used to summarize the patient demographics and clinical characteristics. Comparative and multivariate analyses were performed to assess the impact of different risk factors on patient outcomes.
Result
In the URL registry, we recorded 73 cases with PMBCL. The yearly enrollment distribution is as follows: 2019 - 9 patients (12%), 2020 - 20 patients (27%), 2021 - 11 patients (15%), 2022 - 8 patients (11%), 2023 - 18 patients (25%), and 2024 - 7 patients (10%). The median age of patients was 42 years (range 23 - 82), with a male:female ratio of 0.51:0.49. According to the clinical and laboratory factors: 50 (68%) patients had an ECOG score of 0-1, and 23 (32%) had an ECOG score 2. Early stage (I - II) were observed in 17 (23%) and 30 (41%) patients, while advanced stage (III - IV) was observed in 4 (5%) and 22 (30%) patients respectively. ≥ 1 extranodal involvement was present in 47 (64%) of the patients. Bulky disease was observed in 56 (77%) of the patients, with a median bulky volume of 93.2 cm2 (95% CI: 67.2 - 119.2). Bone marrow involvement was found in 1 %. Elevated LDH was observed in 48 (65%) patients. Sixty-seven (92%) patients have finished their treatment. Sixty-one (91%) of them were treated with R-DA-EPOCH, and 6 (9%) received R-CHOP regimen. Twelve (16%) received RT following chemotherapy. Due to high risk of CNS relapse, 17 (25%) patients received HD Mtx, or intrathecal prophylaxis. CR was achieved in 51 (78%), PR in 6 (9%), SD in 3 (8%), and 4 with progressive disease (5%) patients. The 3-year OS was 83% (95% CI: 0.6 - 0.9). The 3-year PFS was 81% (95% CI: 0.66 - 0.89), with the median OS and PFS not reached. Correlation between survival rates and clinical and laboratory data (ECOG, stage, LDH, Bulky, and ≥ 1 extranodal site) was not found.
Conclusion
This analysis confirmed that standard anthracycline-based chemotherapy regimens, in combination with Rituximab in patients with PMBCL, yielded a high overall response rate, with 3-year OS and PFS rates of 83% and 81%, respectively. While these outcomes are lower than previously reported, it is important to note that our data is derived from real-world evidence, which did not impose any restrictions for inclusion in the registry. Additionally, it is reasonable to consider that variations in treatment approaches to second-line therapy, due to the limited availability of novel drugs in Ukraine, may have influenced these results.