59P Checkpoint inhibitors and conventional therapy for central nervous system lymphoma

Abstract Background Primary (PCNSL) and secondary (SCNSL) central nervous system lymphoma still carry a poor prognosis. Treatment of relapsed/refractory (r/r) CNS lymphoma remains a challenge. Biological features of CNS lymphoma determine the opportunity to use checkpoint inhibitors in r/r CNS lymphoma. Methods Analysis included 35 patients with CNS lymphoma treated at the First Pavlov Saint Petersburg state medical University between 2010 and 2019. SCNSL comprised 54% of patients (n = 19), PCNSL - 40% (n = 14), and 6% (n = 2) had CNS involvement in primary testicular lymphoma (PTL). Latter would further be analysed together with PCNSL. Median age at a diagnosis was 56 (30-65) in pts with PCNSL and 48 (20-65) in pts with SCNSL. Tumor histology was diffuse large B-cell lymphoma in 83% of cases. Relapsed or refractory CNS lymphoma was the case in 21 pts (60%): PCNSL – 81% (n = 13/16), SCNSL – 42% (n = 8/19). Nivolumab (nivo) was used in 12 pts: PCNSL – 44% (n = 7/16), SCNSL – 26% (n = 5/19). Median follow-up was 16 months (mo) (0-99): 24,5 mo (0-99) for PCNSL, 12 mo (1-34) for SCNSL pts. One patient had been infected with HIV. Results Treatment related mortality was 11% (n = 4/35). 1-year overall survival (OS) was 74% in PCNSL and 69% in SCNSL group. 6-months OS of r/r disease was 75% for PCNSL and 33% for SCNSL. Patients received nivo at dose 3 mg/kg (n = 3), 1 mg/kg (n = 6), 100 mg (n = 3) и 200 mg (n = 1). Median follow-up in pts receiving nivo was 7 mo (0-31). Objective response rate was 58% (n = 7). Complete response was seen in 6 pts (3 PCNSL, 3 SCNSL), partial response – in 1 PCNSL patient, 4 pts had stable disease (2 PCNSL, 2 SCNSL), disease progression was the case in 1 patient with PCNSL. Adverse events (AE) were grade 2 immune arthritis and maculopapular rash. The was no grade 3-4 AE. Eight patients who received nivo are alive at the moment of analysis. Tumor resection was performed in 8 (23%) pts (6 with PCNSL and 2 SCNSL). Consolidation took place in 11 (31%) pts (4 PCNSL, 7 SCNSL). Radiotherapy was performed in 11 pts (31%): 5 PCNSL, 4 SCNSL. Autologous hematopoietic stem cell transplant was performed in 1 patient with PCNSL and 5 pts with SCNSL. Conclusion Nivo is a safe and efficient option in some pts with CNS lymphoma. Appropriateness, timing and optimal regimen of nivo therapy should be determined in prospective trials. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.