Methotrexate re-challenge for recurrent primary central nervous system lymphoma

The prognosis of primary CNS lymphoma (PCNSL) recurring after methotrexate is poor (objective response rates [ORR] = 26-53 %; 1-year overall survival [OS] = 35-57 %). Salvage PCNSL chemotherapies have been based on the use of different agents to avoid cross-resistance; however, methotrexate is the most active agent in PCNSL, and methotrexate re-challenge may be an effective strategy for recurrent disease. We report our experience with methotrexate re-challenge in PCNSL. We reviewed 39 patients with histologically confirmed PCNSL who responded to methotrexate at initial diagnosis, experienced disease relapse and received methotrexate re-challenge. At the time of re-challenge, median age was 66 and median Karnofsky performance score (KPS) was 70. Median time from initial diagnosis was 26 m. Twenty-six patients were at first relapse and 13 at second or later relapse. At re-challenge, methotrexate was given in combination with other agents to 33 patients and as a single agent to six. The objective response rate was 85 %, with a complete response in 29 (75 %) patients, partial response in four (10 %) and disease progression in six (15 %). At median follow-up of 26 m, the median progression-free survival was 16 m; 1-year OS was 79 % (95 % CI 63-89) and median OS was 41 m. KPS was a prognostic factor for progression free survival (p = 0.04). In this population selected by previous methotrexate response, methotrexate re-challenge was a safe and effective strategy, indicating chemosensitivity was retained. Efficacy compared favorably to other salvage treatments suggesting methotrexate re-challenge should be considered in recurrent PCNSL patients who previously responded to methotrexate.