This study is testing a new drug called NX-5948 to help adults with certain types of blood cancers that have come back or don't respond to other treatments. These cancers are called B-cell malignancies, which affect a type of white blood cell. The study has two parts: Phase 1a and Phase 1b. In Phase 1a, doctors will find the safest dose of NX-5948. In Phase 1b, they will see how well it works. To join, you must be 18 or older, have already tried other treatments, and have one of these conditions: Chronic Lymphocytic Leukemia (CLL), Small Lymphocytic Lymphoma (SLL), Diffuse Large B-cell Lymphoma (DLBCL), Mantle Cell Lymphoma (MCL), Waldenstrom Macroglobulinemia (WM), Marginal Zone Lymphoma (MZL), Follicular Lymphoma (FL), or Primary Central Nervous System Lymphoma (PCNSL).

• The study is open-label, meaning both doctors and patients know what treatment is being given.
• You may need to stop certain medications before joining.
• Participation may help understand how well NX-5948 works and its safety.