SL-401 in Combination With Azacitidine or Azacitidine/Venetoclax in Acute Myeloid Leukemia (AML), High-Risk Myelodysplastic Syndrome (MDS) or Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN)

This trial is testing a drug called SL-401 combined with azacitidine (with or without venetoclax) for patients with certain blood cancers — including acute myeloid leukemia (AML), high-risk myelodysplastic syndrome (MDS), or a rare cancer called BPDCN — that have not responded to or have come back after treatment. **You may be eligible if...** - You are 18 years or older - You have been diagnosed with AML, high-risk MDS, or BPDCN (confirmed by biopsy) - Your cancer cells show a protein called CD123 (confirmed by a lab test within the past 3 months) - For AML: your cancer came back or didn't respond to treatment, OR you are newly diagnosed but not able to handle intensive chemotherapy - For MDS: more than 10% of your bone marrow cells are abnormal blast cells - For BPDCN: your cancer came back or didn't respond to treatment - Your heart, liver, kidney, and other organ functions are in acceptable ranges **You may NOT be eligible if...** - Your cancer cells do not show the CD123 protein marker - You have serious heart problems (ejection fraction below normal) - Your liver, kidney, or albumin (blood protein) levels are outside the required ranges - You have an active, uncontrolled infection Talk to your doctor to see if this trial is right for you.