Specific KIR-HLA genotypes predict outcomes of refractory or recurrent primary central nervous system lymphoma

Purpose: An effective salvage regimen for re-induction of remission is lacking for refractory or recurrent primary central nervous system lymphoma (r/r PCNSL). This study aimed to evaluate the efficacy and safety of high dose cytarabine plus temozolomide in treating r/r PCNSL and explore the prognostic factors Methods A single-center retrospective cohort study was conducted to access the efficacy and safety of high dose cytarabine and temozolomide (AT) in r/r PCNSL patients. KIR and HLA genotyping were performed from peripheral blood sample of each patient. Results Thirty PCNSL patients receiving AT regimen (cytarabine 3g/m 2 for 2 days combined with temozolomide 150mg/m 2 for 5 days) in our institution were analyzed. The median age was 65 years (range 25–79 years). 43.4% of patients (13/30) achieved overall response with a median follow up of 16 months (95% confidence interval [CI]:11–23 months). The median PFS and OS of the cohort were 1.75 months (95% CI:1–4 months) and 19.5 months (95%CI:11 months to not calculable), respectively. Patients harboring KIR3DL1/HLA-B genotypes predicting low affinity had a higher response rate (p = 0.042) and longer median PFS (3 months) than those with KIR3DL1/HLA-B genotypes predicting high affinity (1 month) (p = 0.0047). Cox regression analysis indicated that KIR/HLA-B genotypes were independently associated with the PFS (p = 0.042). But it had no impact on the OS of the cohort. Toxicity of AT treatment was mild and manageable. Conclusion AT regimen was well tolerated and patients with specific KIR-HLA genotypes may benefit from it.