A Phase II Study of Cladribine and Low Dose Cytarabine in Combination With Venetoclax, Alternating With Azacitidine and Venetoclax, in Patients With Higher-risk Myeloproliferative Chronic Myelomonocytic Leukemia or Higher-risk Myelodysplastic Syndromes With Excess Blasts

This study is testing a combination of chemotherapy drugs (cladribine, low-dose cytarabine, and venetoclax alternating with azacitidine and venetoclax) in people with higher-risk myelodysplastic syndrome (MDS) or chronic myelomonocytic leukemia (CMML) — blood disorders where the bone marrow is not making healthy blood cells — that have not responded to or have relapsed after standard treatments. **You may be eligible if...** - You are 18 or older - You have been diagnosed with higher-risk MDS or CMML (as defined by WHO and risk scoring systems) - Your disease has either not responded to or has relapsed after standard hypomethylating agents (e.g., azacitidine or decitabine), OR you are newly diagnosed and not eligible for more intensive chemotherapy - Your organ function is within acceptable ranges **You may NOT be eligible if...** - You have a different type of leukemia - You have significant heart, liver, or kidney problems - You are pregnant or breastfeeding - You have active serious infections Talk to your doctor to see if this trial is right for you.