Cladribine and cytarabine in children refractory high risk multisystem Langerhans cell histiocytosis

There is no uniform regimen for refractory Langerhans cell histiocytosis (LCH). We retrospectively described patients with refractory multisystem and risk organ involvement LCH treated with the low-dose (Ara-c, 100 mg/m²/d × 5day; 2-CDA, 5 mg/m²/d × 5day) chemotherapy (LDC) and the intermediate-dose (Ara-c, 500 mg/m²/d × 5day; 2-CDA, 9 mg/m²/d × 5day) chemotherapy (IDC). 26 patients and 10 patients receiving the LDC and IDC regimen from January 2013 to December 2016 were included in the study. The overall response rate exhibited no significant difference between the LDC and IDC groups after four courses (76.9% vs 90%, P = 0.375) and eight courses (80.8% vs 100%, P = 0.135) of treatment. No statistical differences in the overall survival rate were observed between the two groups, but 5-year event-free survival rate of patients in the IDC group was higher than that in the LDC group at the median follow-up of 6.16 and 5.07 years (88.9% vs 52.9%, P = 0.033). The patients in the IDC group had more severe myelosuppression than those in the LDC group (grade 3/4 myelosuppression, 80% vs 19.2%, P = 0.001). The intermediate-dose regimen of 2CDA and Ara-c had a higher event-free survival rate and a similar overall survival rate compared with the low-dose regimen.