Walking a Tightrope: Dosage Modifications and Treatment Outcomes of All-Trans-Retinoic Acid, Arsenic Trioxide, and Daunorubicin for High-Risk Acute Promyelocytic Leukemia

PURPOSE: The use of all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) in the treatment of low- and intermediate-risk acute promyelocytic leukemia (APL) is the standard of care. We report the combined use of ATRA, ATO, and daunorubicin (DNR) in patients newly diagnosed with high-risk APL. The primary focus was to describe the drug dosage modifications made in the real-world scenario. METHODS: In this descriptive study, we included 16 out of 28 patients with high-risk APL from two tertiary care centers in South India (Vijayawada and Trichy) between January 2015 and December 2018. A unique approach of initiating ATRA at a dose of 25 mg/m(2) on day 1 and escalation to 45 mg/m(2) after cytoreduction with DNR and hydroxyurea was followed in all patients to avert differentiation syndrome, in the setting of hyperleukocytosis at presentation. RESULTS: All patients who survived the first 3 days of admission achieved complete remission after a median duration of 29 days. There were no deaths during induction or consolidation, and the regimen was well tolerated; two patients developed grade 3/4 peripheral neuropathy requiring treatment modification. After a median follow-up duration of 1.9 years, there were no hematologic or molecular relapses. CONCLUSION: The study sheds light on the modifications made to recommended dosages of ATRA, ATO, and DNR to optimize outcomes in high-risk APL and reaffirms the importance of ATO use in the front-line setting to achieve durable responses with minimal toxicity.