Clinical Characteristics of Chilean Adult Patients with Acute Myeloid Leukemia (AML): Analysis within the Framework of the Epidemiological Registry of AML of the Pethema Group

Introduction: AML is the most common acute leukemia in adults, with a median age at diagnosis of 68 years and a 5-year Relative Survival of 29.5%, as reported in the United States. Epidemiological data on AML in Chile are scarce and come from records from a single center. Since 2021, Chile has participated in the epidemiological registry of AML carried out online by PETHEMA group. This is the first analysis that includes multiple Chilean centers with patients coming from our 3 health systems.

Objective: To describe the clinical characteristics of Chilean adult patients with AML in the framework of the PETHEMA AML registry.

Methodology: This is a multicenter, epidemiological registry that analyses Chilean patients with AML with >15 years at diagnosis coming from 16 centers, included in the Epidemiologic Registry of AML from PETHEMA group (NCT02607059). Data was entered in an online platform. Each participating center is approved by a local Ethic Committee.

Results: A total of 539 patients diagnosed between March 1996 and January 2022 were analyzed. The median age at diagnosis was 58 years, 52.8% were male. Most patients had an ECOG <2 at diagnosis. 18% were secondary AML. The most frequent FAB subtype was M4 (22%). 42% of the patients could not be classified by cytogenetics as this was not performed or was not available. Of the patients with available cytogenetics, 16.2% corresponded to the favorable group, 62.5% to the intermediate group, and 21.3% to the unfavorable group. Less than 50% of patients had molecular evaluation of NPM1 and FLT3-ITD at diagnosis. The most frequent induction treatment was "3+7" (daunorubicin + cytarabine):75.97% in <60 years and 20.67% in >60 years. Patients >60 years of age received mainly palliative support after diagnosis (53.36%). Among treated patients, the complete response rate was 52%, 22.1% refractory, and death on induction was 9.6%. In consolidation, the most used regimen was high-dose cytarabine (65.7% in consolidation 1). Only 7.43% of the patients received a haematopoietic stem cell transplantation (HSCT) (39 allogeneic, 1 autologous), mainly haploidentical and with myeloablative conditioning regimen. The median overall survival (OS) was 24.3 weeks, with no difference between genders (male: 23 weeks, female: 21.1 weeks), but we found clear difference with respect to age (<60 years: 47.6 weeks versus >60 years: 10.4 weeks, p < 0,001), figure1). Median disease-free survival (DFS) was 14.7 weeks (32.6 weeks in <60 years versus 8.9 weeks in >60 years, p < 0,001).

Conclusion: This is the first multicenter analysis of adult patients with AML in Chile. Access to a better diagnosis and better risk classification would optimize therapeutic efforts and increase the chance of HSCT, which is very scarce in our reality. The increase of high-intensity therapeutic approach in patients >60 years and treated those aged over 60 is a priority to improve OS and DFS in our AML patients.