Introduction
T lymphoblastic leukemia/lymphoma (T-ALL/LBL) and Burkitt lymphoma (BL) are uncommon, highly aggressive B and T cell neoplasms [
1,
2]. T-ALL/LBL is committed to immature precursor T lymphoblasts, clinically characterized by bone marrow or blood involvement with or without primary involvement of the thymus and nodal or extranodal sites. It is more common in male adolescents with a male to female ratio of 2.5. A bone marrow involvement of > 25% blasts is used as the threshold for defining leukemia [
2‐
7].
Burkitt lymphoma originates from mature B cells located in the germinal center or post germinal center and can be divided into three distinct entities (i) endemic, which is associated with the Epstein-Barr virus occurring mainly in equatorial Africa and South America and mainly affecting children under the age of 18 with an incidence of 3–6/100.000 per year (ii) immunodeficiency-related, typically associated with HIV with an incidence of 22/100.000 per year in the United States and (iii) sporadic BL, which occurs mainly in Europe, East Asia and North America, with a median age at diagnosis of 45 years and an incidence of 2.5/ per million per year in adults [
1,
8‐
10]. The clinical presentation is characterized by an extremely short doubling time often presenting in extra nodal (e.g. abdominal) sites or as an acute leukemia (1,10). Translocations involving the
myc oncogene on chromosome 8 are highly characteristic but not specific [
11].
Current treatment approaches using ALL-based regimen with or without autologous stem cell transplantation or DA-EPOCH give survival rates of 90% for BL and 70% for adult T-ALL/LBL [
12,
13].
Herein, we report our single-centre approach using a short and intensive ALL-like induction/consolidation according to the respective GMALL protocols followed by autologous and/or allogeneic SCT for the treatment of advanced T-ALL/LBL and BL.
Discussion
This retrospective single-center analysis shows clear benefits of an early SCT approach to patients with advanced stage BL and T-ALL/LBL. It results in shorter treatment duration and surprisingly good tolerability of early intensification.
Nearly all patients underwent remission induction/consolidation according to the GMALL 07/2003 or the GMALL B-ALL/NHL 2002 protocol.
Patients with BL in first CR achieved a 10-year OS and EFS of 91%. Compared to a study analyzing the results of the GMALL B-ALL/NHL 2002 protocol in patients with BL, the 5-year OS was similar to our study, except for the longer duration of conventional treatment, namely 94% in patients < 55 years and 64% in patients > 55 years [
15]. Similar results were found in a large study by Evens et al. of patients with BL treated at 30 different US cancer centers. The majority of these patients were treated according to the CODOX-M/IVAC regimen in combination with rituximab in 90% of patients [
16]. This shows again that early SCT can achieve outcomes superior to those of previously used regimens, but with a dramatic reduction in treatment duration, namely a median time of four months from diagnosis to SCT. In addition, the improved treatment outcome is demonstrated when CR is achieved prior to SCT.
T-ALL/LBL patients in the first CR1 achieved a 5-year OS and EFS rate of identical 73%. In addition, the entire patient cohort reached a 5-year OS and EFS of 65%. Compared to a study published by Fredman et al. using the GMALL 07/2003 protocol in ALL and LBL in Israel in a cohort for 127 patients, a 5-year OS of 68% was achieved in the T-ALL group, similar to our study [
17]. In an update of the GMALL study 08/2013, a 3-year OS rate of 78% was described in 208 T-ALL patients. In high-risk T-ALL/LBL patients in CR1 who received allogeneic SCT, a 3-year OS rate of 68% was observed with CIR and TRM rates of 26% and 15%, respectively [
18].
In our study, we could demonstrate that comparable results can be achieved with a significant reduction in the median treatment duration of three months after diagnosis. The limitating factor in this comparison is the smaller number of patients enrolled.
A multicenter phase II study published in 2005 by the Dutch-Belgian Hemato-Oncology Cooperative Group (HOVON) analyzed the outcome of autologous SCT after short course of chemotherapy in patients with BL and LBL with a 5-year OS of 81% in patients with BL and 40% in patients with LBL. The reason for these rather unsatisfactory results could be the advanced stage of patients; namely 37% of patients with BL and 53% of patients with LBL belonged to the high-intermediate or high-risk group after aa-IPI [
19]. In our study, we could nicely demonstrate that achieving prior CR is of more prognostic value than the advanced stage at the beginning of diagnosis. However, due to the small number of treated patients, every firm conclusion will remain limited in its full strength.
In addition, a meta-analysis by Hoelzer et al. of early autologous and allogeneic SCT for T-ALL/LBL showed that patients who received autologous SCT in CR1 achieved a DFS of 61%. However, patients who did not undergo autologous SCT in CR had a shorter DFS of only 47% [
13]. This again indicates the clear benefit of SCT in CR1.
Furthermore, all patients in our study had an NRM rate of zero. This can be attributed to the short treatment duration with early SCT and the good tolerability of SCT. It highlights the value of implementing SCT and an intensified protocol from the very far beginning for a limited time in the treatment approach of BL and T-ALL/LBL patients to omit long-lasting chemotherapeutic-based regimens.
Nevertheless, our study has several limitations, such as limited patient number, single center analysis, retrospective nature of the study with missing data, and lack of MRD status including unestablished modalities and experience with assessing MRD years ago. All these factors may influence the analyses.
In conclusion, the results of our single-center study with a long overall observation period of 15 years stresses a clear benefit of early SCT in patients with advanced-stage BL and T-LBL in CR1 without major toxicity/mortality rates. Further research is necessary to better define those patients who might benefit most from such an approach incorporating better molecular subtyping, early MRD and PET diagnostics and to identify those patients who are at high risk of early relapse or with refractory disease requiring front-line allogeneic SCT.
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