216P - Lenalidomide maintenance after whole brain radiotherapy in relapsed/refractory primary CNS lymphoma

Background

Prognosis of patients with relapsed primary CNS lymphoma (PCNSL) not eligible for high dose methotrexate salvage is poor. Systemic therapy with agents like temozolomide, ibrutinib, lenalidomide results in overall response rates of 31 to 67% and median PFS from 1.9 to 7.8 months. Whole brain radiotherapy (WBRT) leads to a high overall response rate of 75 to 80% but a short PFS of 9 to 10 months. A combination of WBRT followed by lenalidomide with the aim of prolonging remission seems an attractive strategy.

Methods

A retrospective analysis of patients with relapsed PCNSL receiving WBRT followed by lenalidomide.

Results

Twelve patients with a median age of 57 years (range 27 to 78) were treated with WBRT followed by lenalidomide. Eight patients were refractory (Primary progressive 4, relapse and refractory 4), 1 patient was relapsed but not refractory and 3 patients were newly diagnosed but not eligible for high dose methotrexate based treatment. WBRT doses ranged from 30 - 36 Gy and 8 patients received a boost to tumor bed with 4 to 14.4 Gy. Lenalidomide dose used was 25 mg in 9 patients, 2 patients required dose reduction to 15 mg and one patient received pomalidomide 4 mg in view of renal dysfunction. The median duration of lenalidomide use was 24 months (range 5-30 months). The median follow up of study cohort post WBRT is 25 months. Best responses achieved were CR in 8 patients, 3 patients achieving PR and 1 patient had stable disease. Five patients have progressed and 3 died due to disease progression. One additioanal death was due to unrelated cause. Two patient who had progressed after stopping lenalidomide after 2 years have been rechallaned with lenalidomide and both have achieved response (CR and PR). Thus eight patients have ongoing responses including 2 after rechallange with lenalidomide and three patients have completed 2 years of lenalidomide treatment, are off treatment, in complete remission at last follow up. The median PFS and OS is 25 months (range 4.8 - 64).

Conclusions

Lenalidomide following WBRT leads to longer PFS than WBRT or lenalidomide alone and seems an effective approach. This should be explored in a larger cohort of patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.