Immunodeficiency Secondary to Malignancies and Biologics

There are many causes for secondary immunodeficiency (SID), which commonly presents with increased risk of infections. B-cell malignancies (multiple myeloma, chronic lymphocytic leukemia, non-Hodgkin’s lymphoma) and chemotherapeutics with B-cell depleting treatments such as rituximab are increasingly recognized risk factors for SID. This chapter discusses the diagnostic approach to patients with SID due to malignancy and biologics, including evaluation of immunoglobulin (Ig) levels and the importance of assessing a vaccine response. The chapter also discusses management options with prophylactic vaccination, prophylactic antibiotics, and Ig replacement (IgR), with a discussion on the pros and cons of intravenous versus subcutaneous administration of IgR