This study begins with about one month of screening tests, such as blood tests and exams, to see if a person can join. If eligible, people will be placed into one of two groups by chance. One group will receive a medicine called lisaftoclax with another medicine called azacitidine. The other group will receive a placebo, which has no active medicine, along with azacitidine.

Treatment happens in cycles that last 28 days. During each cycle, lisaftoclax or placebo is taken by mouth for 14 days, and azacitidine is given by a shot or through a vein for 7 days. At the start, there will be more clinic visits, and visits may become less frequent over time. Participants will continue treatment as long as it is helping and side effects are manageable. After stopping treatment, there will be a follow up visit to check safety.

Higher-risk myelodysplastic syndrome (a disease where the bone marrow does not make healthy blood cells).

People can join this study if they are adults who have a blood problem called higher risk myelodysplastic syndrome that was just diagnosed. They cannot have received treatment for this condition before. They also cannot be taking part in another research study at the same time.

This study is testing a new medicine called lisaftoclax when it is used together with a standard treatment called azacitidine. Researchers want to see if adding the new medicine helps people more than using the standard treatment alone. They will look at whether the combination is safe, if it helps people live longer, and if it improves blood counts.