The APL-R2007 trial, sponsored by the PETHEMA Foundation, investigates the efficacy of arsenic trioxide (ATO) in treating relapsed acute promyelocytic leukemia (APL). ATO has demonstrated remission rates exceeding 80% in prior studies and is already approved for relapsed and refractory APL in both Europe and the USA. The market for APL therapies is competitive, with ATRA and other agents also in use. The trial's findings could reinforce ATO's position in the treatment landscape, particularly for patients not eligible for transplantation. Given the high relapse rates associated with APL, successful outcomes could lead to increased adoption of ATO in clinical practice, impacting market share and revenue potential for the PETHEMA Foundation and potential partners. Diligence should focus on the long-term safety profile and comparative efficacy against existing therapies.