Immune checkpoint inhibitor therapy in children and adolescents with refractory/relapsed Hodgkin lymphoma: a case series

   Ten-year progression-free survival in children, adolescents and young adults with relapsed/refractory Hodgkin lymphoma (r/r HL) does not exceed 50 %. Brentuximab vedotin (BV) and immune checkpoint inhibitors (ICIs), such as nivolumab and pembrolizumab, are successfully used for the treatment of adults with r/r HL. In this study, we analyzed our experience of ICI treatment of children and adolescents with r/r HL. This study was retrospective and included patients with r/r HL under 18 years of age, who received ICI therapy. Twenty patients were included. All of them had been treated with BV, 35 % (n = 7) of patients had undergone auto-HSCT before treatment with ICIs. Among all patients, 45% (n = 9) received ICIs for the first refractory relapse, 40 % (n = 8) due to refractory disease progression and 15 % (n = 3) received therapy for the second relapse. Two patients received ICIs in combination with other drugs, the response to therapy in 2 patients was unknown. Nine (56 %) of 16 patients achieved a metabolic response, one patient had no evidence of vital tumor cells based on the results of a biopsy of a lesion positive on positron emission tomography, thus a response was achieved in 10 (63%) patients. The survival rate analysis included 20 patients. Median follow-up from ICIs initiation was 1.2 years (interquartile range: 0.7–1.5 years). The probability of 1-year overall survival (OS) rate reaches 69 % (95 % confidence interval (CI) 46.4–91.6), 2-year OS – 60.4 % (95 % CI 35.1–85.7), 3-year OS – 40.3 % (95 % CI 4–76.6). In this study, we demonstrated the effectiveness of the treatment with ICIs as an element of therapy in children and adolescents with r/r HL, who had not responded to previous lines of therapy, including BV. The patients' parents gave consent to the use of their children's data, including photographs, for research purposes and in publications.