Outcomes of infantile leukemia in a Saudi multicenter cohort: patterns of treatment response, treatment failure, relapse, and survival.

Background: Infantile leukemia is a rare and aggressive form of pediatric leukemia associated with high rates of treatment failure, relapse, and mortality. Despite advances in leukemia therapy, evidence from Saudi Arabia remains limited, particularly regarding treatment response and survival outcomes among infants with acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Aim: This study aimed to describe treatment response, treatment failure, relapse, overall survival, and event-free survival among infants with acute leukemia treated at two tertiary referral centers in Saudi Arabia, and to explore outcome differences according to leukemia subtype. Methods: A retrospective multicenter observational cohort study was conducted at King Faisal Specialist Hospital and Research Centre in Riyadh and Jeddah. The study included 41 patients diagnosed with infantile leukemia between January 2012 and December 2021. Data were extracted from medical records using a structured data collection form. Demographic, clinical, treatment-response, relapse, treatment-failure, and survival outcomes were summarized using descriptive statistics. Comparisons between ALL and AML were performed using Fisher's exact test where appropriate because of small cell counts. Overall survival and event-free survival were estimated using Kaplan-Meier analysis and compared using the log-rank test. Results: Of the 41 patients, 24 (58.5%) had ALL and 17 (41.5%) had AML. At last follow-up, 22 patients (53.7%) were alive and 19 (46.3%) had died. Among patients evaluable after first-line therapy, 20 of 26 (76.9%) achieved first complete remission. Disease reactivation or relapse occurred in 11 patients (26.8%), death in remission in 6 (14.6%), and treatment failure or refractory disease in 6 (14.6%). Median overall survival was not reached for the total cohort, while median event-free survival was 23.27 months. No statistically significant differences were observed between ALL and AML in overall survival, log-rank p = .930, or event-free survival, log-rank p = .778. Conclusion: Infantile leukemia was associated with considerable adverse outcomes in this Saudi multicenter cohort, including relapse, death in remission, treatment failure, and mortality. Leukemia subtype alone was not significantly associated with survival or adverse outcome patterns. These findings should be interpreted as descriptive and hypothesis-generating because of the small sample size and limited statistical power.