Autologous hematopoietic stem cell transplantation in children with relapsed or refractory Hodgkin lymphoma
Authors: Kozlov A. V. , Kazantsev I. V. , Morozova E. V. , Yukhta T. V. , Nikolayev I. Yu. , Tolkunova P. S. , Gevorgyan A. G. , Shvetsov A. N. , Potanin A. A. , Fedorova L. V. , Botina A. V. , Baykov V. V. , Punanov Yu. A. , Mikhailova N. B. , Kulagin A. D. , Zubarovskaya L. S. 
Published: June 2022

The majority of patients with Hodgkin lymphoma (HL) are cured, which represents one of the best cure rates in oncology. However, the prognosis is not as favorable in case of relapsed or refractory (RR) disease. Autologous hematopoietic stem cell transplantation (auto-HSCT) is an effective way to consolidate remission in patients with RR HL. Despite the many years of experience and the availability of results of randomized trials confirming the efficacy of high-dose chemotherapy in adults, the role of auto-HSCT in children with HL has not been studied as extensively, and there are only a limited number of publications on the subject. As is the case with the majority of other pediatric tumors, RR HL is a rare entity, which is why it is so difficult to study it. Here we share the experience of the R. M. Gorbacheva Research Institute for Pediatric Oncology, Hematology and Transplantation in auto-HSCT in children and adolescents with HL. The study was approved by an Independent Ethics Committee and the Scientific Council of the I.P. Pavlov First Saint-Petersburg State Medical University. We included 54 patients with RR HL who had undergone auto-HSCT during the period from 2007 to 2021. Refractory disease (n = 29; 54 %) was diagnosed in case of HL progression either during first-line therapy or in the first 3 months after the completion of the treatment. Relapsed disease was diagnosed in 25 (46 %) children. Early HL relapse (< 12 months since the start of therapy) was evident in 18 (72 %) patients, while late HL relapse (≥ 12 months since the start of therapy) occurred in 7 (28 %) children. The median number of lines of therapy before auto-HSCT was 3 (1–6). The first line of treatment was chemotherapy in accordance with the GPOH-HD (n = 27; 50 %), BEACOPP (n = 19; 35 %), or other protocols (n = 8; 15 %); the second line involved the use of IEP/ABVD (n = 14; 27 %), DHAP (n = 12; 23%), ICE (n = 13; 25 %), or other combinations (n = 13; 25%); and third-line treatment consisted of DHAP (n = 9; 29 %), a combination of brentuximab vedotin and bendamustine (n = 8; 26%), immune checkpoint inhibitors (ICIs) (n = 7; 22.5 %) or other regimens (n = 7; 22.5 %). ICIs were used for remission induction prior to auto-HSCT in 14 (26 %) patients. Response was assessed using the Lugano classification. Status before transplantation: complete remission (CR) – 21 (39 %) patients, partial remission (PR) – 30 (56 %), disease stabilization – 2 (3.5 %), disease progression – 1 (1.5 %). The BEAM conditioning regimen was used in 17 (31 %) patients, and the BeEAM regimen – in 32 (59 %) patients. The 3-, 5- and 10-year overall survival (OS) was 88% (95 % confidence interval (CI) 74–95), 80% (95 % CI 62–90) and 63% (95 % CI 34–81) respectively. The 10-year progression-free survival (PFS) was 46% (95 % CI 24–65). The median follow-up was 3.3 (0.1–12.3) years. The long-term PFS in children with CR and PR was 72% (95 % CI 41–89) and 33 % (95 % CI 8–61) respectively (p = 0.067). A total of 9 (16.7 %) patients died during follow-up. The main cause of death was progressive HL (n = 6), while some patients died in the early post-transplant period due to infections (n = 3; 5.6 %). The median time to relapse or progression after auto-HSCT was 6 (1–77) months. Out of 17 (31 %) patients with relapsed or progressive HL after auto-HSCT, 9 (53 %) children are alive at a median follow-up of 2.3 (0.7–9) years. Considering that our study included patients who had been more extensively pre-treated (the median number of lines of therapy – 3) than patients in the majority of other studies (the median number of lines of therapy – 2), it can be assumed that our results are superior to historical data. The improvement of transplantation outcomes observed over time can be attributed to better supportive treatment and probably, to the use of immunotherapy. According to the Center for International Blood and Marrow Transplant Research (CIBMTR), it is crucially important that long-term survival in children with RR HL be monitored closely since it can be drastically different from results obtained during the first years of follow-up - due to late relapses and complications of the received treatment. The 10-year survival rates show that the RR HL problem is yet to be resolved. With the help of auto-HSCT, approximately half of children and adolescents with RR HL can be cured. One of the most important favorable prognostic factors in these patients is the achievement of CR before transplantation. The use of immunotherapy for remission induction before auto-HSCT is also promising.