Pb2254: treatment outcome and prognostic factors in children and adolescents with relapsed and refractory classic hodgkin lymphoma

Topic: 17. Hodgkin lymphoma - Clinical Background: Children and adolescents with Hodgkin lymphoma (HL) achieve long-term overall survival rates of over 90%. Despite the high cure rate of HL with initial therapy, 5–10% of patients are primary refractory, and 10–20% will eventually relapse. It is important to identify reliable risk factors in order to guide treatment over the course of the disease. Aims: We aimed to evaluate the outcome of pediatric patients with relapsed or primary refractory classic HL, as well as the impact of all prognostic factors at the time of relapse on the outcome. Methods: A retrospective study including all patients with relapsed and refractory classic HL from July 2007–December 2018 at the Children’s Cancer Hospital Egypt. Results: One hundred twenty-nine patients were diagnosed with refractory or relapsed classic HL. The male-to-female ratio was 1.9:1. The median age at relapse was 11 years. Relapse occurred in 60% of initially high risk patients, in 23% of initially intermediate risk patients, and in 17% of initially low risk patients. 75 percent of relapsed patients were initially stratified as stage III or IV, 25% as stage 2, and none as stage 1. In terms of time to relapse, 18.5% were refractory, 25% relapsed early, and 56.5% relapsed late. Following 2 cycles of salvage, a positron emission tomography/computed tomography (PET/CT) was performed to assess the early response; it was negative in 60% and positive in 40%. Regarding pre-salvage prognostic factors, time to relapse, stage at relapse, and prior chemotherapy burden were significantly associated with survival outcome. Overall survival (OS) and Event-free-survival (EFS) were 38.8% and 25% for those with refractory disease, 68.0% and 49.6% for those with early relapse, and 91.2% and 58.3% for those with late relapse, with corresponding p values of 0.001 and 0.001, respectively. OS and EFS were each 100% for patients with stage I disease at relapse, 80%, 59.3% for those with stage II, 81.7%, 42.3% for stage III, and 68%, 34.5% for stage IV, with p values of 0.001 and 0.001. OS and EFS were 90% and 68.9% for patients who received 4 cycles in the first line, compared to 73.5% and 43.8% for those who received 6 cycles and 75% and 45.8% for those who received 8 cycles, with a p value of 0.04 and 0.18, respectively. B symptoms and bulky disease at relapse were not significantly associated with survival outcome. Those with negative B symptoms had 79% OS and 49.6% EFS, while those with positive B symptoms had 66.1% OS and 44.7% EFS, with p values of 0.59 and 0.45, respectively. OS and EFS for those with non-bulky disease were 77.7% and 49.6%, respectively, compared to 63.6% and 36.4% for those with bulky disease, with p values of 0.09 and 0.1, respectively. The second most important step after the introduction of salvage chemotherapy is response assessment by PET/CT following two cycles. OS and EFS were 91% and 70% for those with negative PET/CT versus 61% and 20% for those with positive PET/CT, with p values of 0.001 and 0.001, respectively. Multivariate analysis identified two predictors of lower EFS: time to relapse and PET/CT response after two cycles of salvage therapy. The 5-year OS and EFS rates for the whole cohort were 75% and 70%, respectively. Summary/Conclusion: The outcome of our cohort is comparable to what has been published in the literature, with time to relapse and early response after 2 cycles of salvage being the most important prognostic factors that can help guide treatment plans at relapse. Keywords: Hodgkin’s lymphoma, Children, Adolescents, relapsed/refractory