Specific KIR-HLA genotypes predict outcomes in refractory or relapsed primary central nervous system lymphoma

Introduction: An effective salvage regimen for the reinduction of remission is lacking for refractory or relapsed primary central nervous system lymphoma (r/r PCNSL). This study aimed to evaluate the efficacy and safety of cytarabine plus temozolomide in treating r/r PCNSL and to explore the associated prognostic factors. Methods: A single-center retrospective cohort study was conducted to assess the efficacy and safety of cytarabine and temozolomide (AT) in r/r PCNSL patients. KIR and HLA genotyping was performed on peripheral blood samples. Results: Thirty PCNSL patients receiving an AT regimen (cytarabine 3 g/m(2) for 2 days combined with temozolomide 150 mg/m(2) for 5 days) in our institution were analyzed. The median age was 65 years (range 25-79 years). A total of 43.4% of patients (13/30) achieved an overall response within a median follow-up of 16 months (95% confidence interval [CI]: 11-23 months). The median PFS and OS of the cohort were 1.5 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 PFS (p = 0.043). However, KIR/HLA-B genotypes had no impact on the OS of the cohort. The toxicity of AT treatment was mild and manageable. Conclusion: The AT regimen was well tolerated, and patients with specific KIR-HLA genotypes may benefit from this regimen.