This clinical study is testing a new drug called NX-5948 in people with certain types of blood cancers that have come back or don't respond to treatment anymore. These cancers are related to B-cells, which are a type of white blood cell. The study is split into two parts. In Phase 1a, different doses of the drug are tested to see how safe it is for patients. In Phase 1b, the best dose from Phase 1a is used to see how well it works against the cancer. To join, you must be at least 18, have a specific type of B-cell cancer, and have tried other treatments before.

• The study will be conducted at multiple locations and is open-label, meaning everyone will know they are getting the drug.
• Participants may need to have several visits and tests throughout the study.
• Participants should not have certain heart problems or other active cancers besides the one being studied.

If you think you meet the criteria, talk to your doctor to see if this study might be right for you.