Impact of the Duration of Methotrexate Administration and the Specific HLA Alleles on the Regressive Methotrexate-Induced Lymphoproliferative Disorders

[Background]

Methotrexate-induced lymphoproliferative disorders (MTX-LPDs) are categorized as iatrogenic diseases and belong to the group of other iatrogenic immunodeficiency-associated LPDs, as defined in the 4th edition of the WHO classification manual for immunodeficiency-associated LPD. The phenomenon of LPD regression after MTX withdrawal is a specific event, directly suggesting an MTX influence on LPD development. Although previous data suggests this regressive phenomenon might be related to Epstein-Barr virus (EBV) infection, the precise pathogenesis still remains to be discovered. To investigate the factors involved in this phenomenon, we analyzed patients with regressive LPD after MTX withdrawal in this study.

[Methods]

Data were collected from 43 patients with autoimmune diseases (ADs) who developed LPD and were treated at our institutions. All diagnoses were confirmed by immunohistochemistry performed on paraffin-embedded tissue sections, along with EBV early RNAs (EBERs). All pathological samples were classified and diagnosed according to the WHO 2016 revision of classification (5th edition). HLA analysis was performed by the PCR-luminex method. The frequency of each HLA allele was determined by referring to the database of an HLA laboratory that has studied HLA alleles. The statistical analyses such as t-tests and the Kaplan-Meier method were performed using EZR software.

[Results]

Of 43 patients with MTX-LPD, the median age of patients at the time of LPD diagnosis was 64.7 years old (range: 41-83). Sixteen men and 27 women were included. The basal ADs were RA (N = 40), psoriasis vulgaris (N = 1), systemic lupus erythematosus (N = 1), and dermatomyositis (N = 1). The median durations of the basal ADs and MTX treatment were 10.5 (0.5-17.8) and 5.1 (0.2-16.3) years, respectively. Histopathological analysis of the LPDs revealed 14 cases of EBV + DLBCL, 6 DLBCL-NOS, 9 Hodgkin lymphoma (HL), 9 LPD, 3 follicular lymphoma (FL), 2 peripheral T-cell lymphoma (PTCL)-NOS, 1 extranodal marginal zone lymphoma of mucosal-associated lymphoid tissue (MALT), 1 plasmablastic lymphoma, and 3 with other LPDs. Regarding the clinical outcome, 32 patients (74%) were alive. After the LPD regression, 19 patients (44%) relapsed or experienced regrowth. Although patients with HL, FL, and other LPDs showed high relapse rates (100%, 67%, and 100%, respectively), the DLBCL-EBV+ and LPD cases had lower relapse rates (11% and 11%, respectively). In addition, patients with the PTCL-NOS and MALT subtypes were disease-free at the time of writing. Five and 10-year OS were 76.4% and 53.2%, respectively.

To investigate any EBV influence, we compared the clinical parameters such as age, sex, clinical stages, serum LDH, serum CRP, serum soluble interleukin-2, MTX dose at the time of LDP development, the disease duration, MTX administration duration, and OS between the EBV+ and EBV - groups. Of 42 patients who underwent an EBER test, 20 patients (48%) were positive. Although for all parameters except MTX duration, significant differences were not detected, a strong association between EBV infection and the median MTX duration was observed (treatment durations in EBV + and EBV- patients were 7.4 years and 4.4 years, respectively; p = 0.0016).

On the basis of the higher frequency seen in Japan, 18 patients with regressive LPD underwent HLA analysis. Ten alleles (A*2402, A*3101, A*1101, B*5101, B*5201, C*0303, DRB1*0405, DRB1*1502, DQB1*0401, and DQB1*0601) were significantly positive compared with the general frequency of these alleles in Japan.

[Summary]

In this study, we analyzed 43 patients with regressive MTX-LPD. After LPD regression, 19 patients (44%) experienced relapsed/regrowth, and their 5 and 10-year OS were 76.4% and 53.2%, respectively. Of 42 patients tested with EBER, 20 patients (48%) were positive. Although the clinical parameters were not significantly influenced by EBV infection, the MTX duration was strongly affected by EBV infection. In addition, 10 specific alleles including A*2402 as seen in Japanese and DRB1*0405 as seen in ADs were significantly positive compared with the general frequency of these alleles in Japan in this study.

[Conclusions]

Our data suggest that a longer period of MTX administration might activate EBV infection dependent on the presence of specific HLA alleles.