Association of Polymorphisms With Leukoencephalopathy Risk in Patients With Primary CNS Lymphoma Treated With Methotrexate-Based Regimens.

OBJECTIVES

The folate antagonist high-dose methotrexate (HD-MTX) is integral to induction chemotherapy for primary CNS lymphoma (PCNSL); however, it can be associated with leukoencephalopathy. Methylenetetrahydrofolate reductase (MTHFR) is involved in intracellular folate depletion. We assessed whether polymorphisms affect the risk of leukoencephalopathy.

METHODS

We retrospectively searched our database at the Massachusetts General Hospital for newly diagnosed PCNSL treated with HD-MTX (without radiotherapy nor intrathecal chemotherapy).

RESULTS

Among 68 patients with PCNSL, polymorphisms were found in 60 individuals (88.2%) including a 677C→T genotype, a 1298A→C genotype, or a combined 677C→T/1298A→C genotype. Neither MTX clearance nor response to induction therapy was affected by specific genotypes, and complete response was achieved in 72.1% of patients by HD-MTX-based induction. However, the 1298A→C genotype was associated with increased frequency and severity of leukoencephalopathy over time (odds ratio 4.0, CI 1.5-11.4). Such genotype predicted treatment-induced leukoencephalopathy with a sensitivity of 71.0% and a specificity of 62.2% (area under the curve 0.67, CI 0.5-0.8; = 0.019). While progression-free survival did not differ in genotype-based subgroups, overall survival was lower for the 1298A→C genotype.

DISCUSSION

The 1298A→C genotype may serve to identify patients with PCNSL at elevated risk of HD-MTX-induced leukoencephalopathy. This seems to translate into reduced survival, potentially due to decreased functional status.