[Clinical features and prognostic analysis of testicular relapse in pediatric acute lymphoblastic leukemia]

Objective: To investigate the clinical features and prognosis of testicular relapse in pediatric acute lymphoblastic leukemia (ALL). Methods: Clinical data including the age, time from initial diagnosis to recurrence, relapse site, and therapeutic effect of 37 pediatric ALL with testicular relapse and treated in Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences between November 2011 and December 2022 were analyzed retrospectively. Patients were grouped according to different clinical data. Kaplan-Meier analysis was used to evaluate the overall survival (OS) rate and event free survival (EFS) rate for univariate analysis, and Cox proportional-hazards regression model was used to evaluate the influencing factors of OS rate and EFS rate for multivariate analysis. Results: The age at initial diagnosis of 37 pediatric testicular relapse patients was (5±3) years and the time from initial diagnosis to testicular recurrence was (37±15) months. The follow-up time was 43 (22, 56) months. Twenty-three patients (62%) were isolated testis relapse. The 5-year OS rate and EFS rate of the 37 relapsed children were (60±9) % and (50±9) % respectively. Univariate analysis showed that the 2-year EFS rate in the group of patients with time from initial diagnosis to testicular recurrence >28 months was significantly higher than those ≤28 months ((69±10)% vs. (11±11)%, P<0.05), 2-year EFS rate of the isolated testicular relapse group was significantly higher than combined relapse group ((66±11)% vs. (20±13) %, P<0.05), 2-year EFS rate of chimeric antigen receptor T (CAR-T) cell treatment after relapse group was significantly higher than without CAR-T cell treatment after relapse group ((78±10)% vs. (15±10)%, P<0.05). ETV6-RUNX1 was the most common genetic aberration in testicular relapsed ALL (38%, 14/37). The 4-year OS and EFS rate of patients with ETV6-RUNX1 positive were (80±13) % and (64±15) %, respectively. Multivariate analysis identified relapse occurred≤28 months after first diagnosis (HR=3.09, 95%CI 1.10-8.72), combined relapse (HR=4.26, 95%CI 1.34-13.52) and CAR-T cell therapy after relapse (HR=0.15,95%CI 0.05-0.51) were independent prognostic factors for 2-year EFS rate (all P<0.05). Conclusions: The outcome of testicular relapse in pediatric ALL was poor. They mainly occurred 3 years after initial diagnosis. ETV6-RUNX1 is the most common abnormal gene.Patients with ETV6-RUNX1 positive often have a favorable outcome. Early relapse and combined relapse indicate unfavorable prognosis, while CAR-T cell therapy could significantly improve the survival rate of children with testicular recurrence.