ACTR-23. COMBINED IMMUNOCHEMOTHERAPY, R-MPV-A, WITH REDUCED OR DEFERRED RADIOTHERAPY FOR PCNSL IMPROVES SURVIVAL WITH FAVORABLE PERFORMANCE AND COGNITIVE FUNCTION

Abstract

BACKGROUND: R-MPV-A (rituximab plus high-dose methotrexate (MTX), procarbazine, vincristine followed by high-dose cytarabine) is an active regimen for primary central nervous system lymphoma (PCNSL). A high complete response (CR) rate by the R-MPV induction phase is expected to reduce or omit neurotoxic whole brain radiotherapy (WBRT) Here we report our single institution experience of treating PCNSL with R-MPV-A with special interests in preservation of neurocognitive function along with radiological findings, and potential prognostic factors. METHODS: Twenty-six cases with newly diagnosed PCNSL treated with R-MPVA since 2012 and followed up more than 6 months were eligible (mean age 71.4, 54% were 70 or older, median KPS 70). The standard R-MPV was used for 5 to 8 cycles. CR cases received either 24 Gy WBRT (< 70 yo) or no WBRT (>=70), followed by cytarabine. KPS, MMSE, and Fazekas score were recorded longitudinally. RESULTS: CR/CRu to R-MPV was achieved in 81%, there were only 6 (23%) progressions and 3 (12%) deaths with median follow up for 23.1 months (6.0-51.8). These outcomes were significantly better than those with previously used HD-MTX monotherapy plus WBRT. WBRT was either omitted or reduced in 13 (50%) or 9 (35%), respectively. Univariate analysis for PFS reveals single lesion (p=0.033), resection (vs. biopsy, p=0.038), age (<70, p=0.092), MMSE (>=24, p=0.089), Fazekas (1, p=0.117), MGMT methylated (p=0.140) as favorable factors. MYD88 L265P mutation status was not associated with PFS. KPS improved in 73% and was maintained in 24, while MMSE and Fazekas score were improved or maintained in 20/23 (87%) and 21/26 (81%), respectively. No cases with WBRT omission experienced worsening of Fazekas score except for one with progression. CONCLUSIONS: R-MPV-A confers a high CR rate even in elderly patients with improvement and preservation of daily activity, neurocognitive and radiological status. Further exploration may be needed for prognostic factors.