Methotrexate temporarily delays CNS relapse in diffuse large B-cell lymphoma

Methotrexate (MTX) yields only temporary prophylactic benefits for patients with diffuse large B-cell lymphoma (DLBCL) at risk of central nervous system (CNS) relapse, a recent study has found.

Researchers enrolled 585 patients with newly diagnosed DLBCL. Half (n=295) of the patients were given prophylaxis: 86 percent (n=253) received intrathecal (IT) MTX, while the remaining 14 percent (n=42) were administered high-dose (HD) MTX. Time to CNS relapse was set as a study endpoint.

Over a median follow-up of 6.8 years, 36 of 585 patients relapsed into CNS, yielding a 5-year risk of 6.5 percent. Fourteen of these patients had been given prophylaxis: 12 with IT-MTX and two with HD-MTX.

Stratifying according to prophylaxis status, the 5-year risks for CNS relapse were 5.5 percent, 5 percent, and 7.5 percent in patients who had been given IT-MTX, HD-MTX, or no prophylaxis, respectively. Risks were comparable across groups (p=0.34).

In terms of timing, relapse occurred a median of 9 months after the first diagnosis in the overall study sample. Patients who had received prophylaxis, either IT or HD, saw a longer time to relapse (19 vs 8 months) than those who had not.

At 1 year, risk of relapse was significantly suppressed for patients on prophylaxis (risk ratio [RR], 0.29, 95 percent confidence interval [CI], 0.08–0.66), an effect that waned over time. By 3 years (RR, 0.51, 95 percent CI, 0.22–1.04) and 5 years (RR, 0.76, 95 percent CI, 0.35–1.50), prophylaxis had no significant impact on the risk of recurrence.