This study is for adults with a type of blood cancer called **acute promyelocytic leukemia (APL)**. It tests a new treatment using pills called ATO and ATRA. **ATO** stands for arsenic trioxide, and **ATRA** is all-trans retinoic acid. These help fight the cancer. To join, you must be 18 to 70 years old, have low to medium-risk APL, and be able to attend all appointments and follow instructions. You can't join if you have heart problems, brain cancer, severe disease, or if you're pregnant or breastfeeding. **Key Points**: - **Study Length**: Participants will need to attend regular visits and follow a treatment plan. - **Treatment**: Includes taking oral capsules of ATO and ATRA. - **Risks/Side Effects**: Cannot participate if you have certain heart issues or are unable to safely take the study meds. **Note:** Always consult with your doctor before joining any study to ensure it’s right for you.