Rapid infusion of high-dose methotrexate resulting in enhanced penetration into cerebrospinal fluid and intensified tumor response in primary central nervous system lymphomas

Object. Twenty-nine nonimmunocompromised patients with primary central nervous system (CNS) lymphoma were treated with high-dose methotrexate (MTX) therapy followed by irradiation. The authors investigated the correlation of infusion schedules with MTX penetration into cerebrospinal fluid (CSF), tumor response, and survival to develop a regimen that would lead to better clinical results. Methods. In this study, 100 mg/kg MTX was administered on either a rapid (3-hour) or regular (6-hour) infusion schedule for two or three cycles. Of 28 assessable patients, a complete or partial response was achieved in 15 (93.8%) of 16 who received rapid and in seven (58.3%) of 12 who received regular infusion therapy (p = 0.034). Rapid infusion significantly increased levels of MTX in the CSF (p < 0.001) and resulted in significant tumor volume reduction (p < 0.001). The mean tumor volume after the first, second, and third cycle of rapid infusion therapy was reduced to 34%, 14%, and 9%, respectively, of the initial volume, whereas the corresponding values were 54%, 42%, and 37% for regular infusion. The reduction between the second and third cycle was small and not significant for either schedule. Despite the longer median survival time in patients who underwent rapid MTX infusion and irradiation (>60 compared with 20 months), the difference in survival was not significant (p = 0.147) because of the small number of patients enrolled. The median survival time was 39.3 months for all assessable patients who received high-dose MTX and radiation therapy, and the median relapse-free survival time was 35.2 months. Conclusions. Rapid infusion enhanced both MTX penetration into the CSF and tumor response and may improve patient survival. Administration of three or more cycles of therapy should be carefully weighed in terms of cytoreductive benefits.