ACALA-R In Predominantly Demyelinating IgM Mediated Neuropathy

This research study involves an experimental drug combination of a targeted therapy and a CD20 antibody. The names of the study drugs involved in this study are/is: * Acalabrutinib * Rituximab or similar CD20 antibody The research study procedures include screening for eligibility and study treatment including evaluations and follow up visits. The study treatment for up to 4 years and will be followed for 2 years after completion of study treatment. It is expected that about 33 people will take part in this research study. This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug to learn whether the drug works in treating a specific disease. "Investigational" means that the drug is being studied. The U.S. Food and Drug Administration (FDA) has not approved acalabrutinib for this specific disease but it has been approved for other uses. The U.S. Food and Drug Administration (FDA) has not approved rituximab or similar CD20 antibody for this specific disease but it has been approved for other uses. * Acalabrutinib is a targeted therapy that blocks a type of protein called Bruton Tyrosine Kinase (BTK) that helps cells live and grow. By blocking BTK, acalabrutinib may kill abnormal cells or stop them from growing. It has been FDA approved for mantle cell lymphoma (MCL). * Rituximab, or biosimilar, is a type of therapy called an antibody that attacks CD20, a protein found on B-cells. Rituximab is approved by the FDA for treating non-Hodgkin lymphoma (NHL). Rituximab is often used to treat WM and IgM MGUS neuropathies. Biosimilars are FDA approved drugs that have been determined to be interchangeable with the original drug.