Early death (ED) in elderly acute promyelocytic leukemia (APL) patients treated with lower induction doses of all-trans retinoic acid (ATRA)

e19012 Background: With the introduction of the differentiating agent ATRA, APL has progressed from being one of the most life-threatening diseases to becoming the most curable subtype of adult AML. However, despite this advancement, death within the first 30 days of treatment amongst elderly patients remains a critical issue with ED rates reportedly as high as 20-50%. There is limited data looking at the elderly population due to often being excluded from clinical trials given age associated with being prominent negative risk factor. Pharmacokinetic studies comparing 25 mg/m2/day and 45 mg/m2/day doses in adult patients have shown similar peak concentrations and mean area under the curve. Notably, low dose ATRA has been offered in pediatric patients in order to reduce incidence of differentiation syndrome. Differentiation syndrome is a key contributor to ED in elderly APL patients causing treatment failure. We propose that lower doses of ATRA in the elderly reduces the impact differentiation syndrome has on induction mortality amongst elderly APL patients and leads to a lower rate of ED. Methods: Fifteen APL patients > 60 years of age were treated. Thirteen received low doses of ATRA (equal to or less than 25mg/m2/day) and two received standard doses of ATRA (45mg/m2/day). Arsenic trioxide was also used in addition to cytoreductive agents, such as cytarabine, hydroxyurea, and idarubicin as needed during induction. Dose reductions and regimens were based on age, comorbidities, and overall clinical judgement. During the course of treatment, further dose reductions and pauses in therapy were made based on clinical course. Results: A total of 15 elderly APL patients were treated between May 2017 and November 2020 at cancer centers within Georgia and South Carolina. The age range was 65-88 years old with a median age of 71 years old. 9/15 (60%) were female and 2/15 (13%) were classified as high risk. 13/15 were Caucasian and the remaining 2 were African American. Amongst the 13 APL patients who received lower doses of ATRA, one ED was noted. This occurred in 81-year-old Caucasian male with low risk APL who had multiple significant comorbidities and elected to halt treatment and pursue hospice. Amongst the 2 low risk APL patients who received standard doses of ATRA, one ED was noted due to differentiation syndrome. This patient also had many significant comorbidities. Conclusions: The ED rate in elderly APL patients treated with low doses of ATRA during induction was noted to be 1/13 (7.7%) which is significantly lower than what has been reported in literature. [Table: see text]