This clinical trial is focused on patients with certain types of blood cancers, specifically B-cell Chronic Lymphocytic Leukemia, Multiple Myeloma, and Non-Hodgkin Lymphoma. These conditions can lead to a weakened immune system, making patients more prone to infections. The study is testing a treatment called Xembify, which is a form of Human Normal Immunoglobulin. This is a substance derived from blood that helps boost the immune system. The trial will compare the effects of Xembify combined with standard medical treatment to a placebo combined with standard medical treatment. The goal is to see if Xembify can help reduce the number of serious infections in these patients.

Participants in the study will receive weekly injections of either Xembify or a placebo for a period of one year. The injections are given under the skin, a method known as subcutaneous injection. Throughout the study, researchers will monitor the participants to track the number of major bacterial infections they experience. The study aims to determine if Xembify can lower the rate of these infections compared to the placebo.

The trial will also look at other factors, such as how long it takes for the first major infection to occur, the total number of infections, and the number of days participants need antibiotics. Additionally, the study will record any hospitalizations due to infections. By gathering this information, researchers hope to better understand the potential benefits of Xembify for patients with these blood cancers and weakened immune systems.