What Are the Disease Risk Factors?

Normal plasma cells produce functional antibodies (IgG, IgA, IgM, IgE, and IgD) that help fight infection. In MM, malignant plasma cells produce a single monoclonal protein and suppress normal antibody production, impairing humoral immunity. Bone marrow involvement can also cause cytopenias. Renal impairment is common and may complicate antimicrobial selection.

What Are the Major Treatment-Related Risk Factors?

Many treatments used throughout the MM disease course increase the risk for infection.1 A 2026 Clinical Journal of Oncology Nursing (CJON) review highlights newer treatments that can cause prolonged immunosuppression, including anti-CD monoclonal antibodies (mAbs), bispecific T-cell engagers (BiTEs), and chimeric antigen receptor (CAR) T-cell therapy.2 Because quadruplet (quad) induction therapy combines drugs that affect different immune mechanisms, infection risk may be cumulative.

Steroids. Dexamethasone remains a mainstay of MM treatment. It suppresses lymphocyte function and immunity. Lower-dose or steroid-sparing approaches may maintain outcomes while reducing toxicity.3
Quad therapy. Quad induction includes:

An anti-CD38 mAb, such as daratumumab or isatuximab
A proteasome inhibitor (PI), such as bortezomib or carfilzomib
An immunomodulatory drug (IMiD), typically lenalidomide
Dexamethasone (dex)

BiTE therapy. BiTEs redirect T cells to attack MM cells but can also cause cytopenias, hypogammaglobulinemia, and impaired T- and B-cell immunity.
CAR T-cell therapy. Infection risk depends on prior MM treatment, lymphodepleting chemotherapy, and immune function. Prolonged cytopenias and hypogammaglobulinemia can contribute to infection risk beyond the immediate treatment period.
Stem cell transplant (SCT). High-dose melphalan before autologous SCT causes profound immunosuppression.

Because B-cell maturation antigen (BCMA) therapy (BiTE or CAR T-cell therapy) targets plasma cells, patients have reduced antibody production, increasing the risk for bacterial, viral, fungal, and opportunistic infections. Early bacterial infections are common when neutropenia is experienced after lymphodepleting chemotherapy or SCT, and delayed immune recovery contributes to later viral, fungal, and opportunistic infections.

What Are the Key Patient-Related Risk Factors?

Multiple myeloma primarily affects older adults, with a median age at diagnosis of approximately 69 years. Diabetes, renal dysfunction, age-related immune decline (immunosenescence), frailty, and reduced functional reserve can increase infection risk.

Multiple myeloma and its treatments can blunt the inflammatory response, so many patients may not show typical signs of infection. Infection may occur without a high fever, chills, rigors, cough, or localized findings. As a result, patients may deteriorate quickly once symptoms appear.

Where Can Oncology Nurses Find Infection Guidelines?

Oncology nurses should know where to find evidence-based guidelines, including:

International Myeloma Working Group (IMWG)
National Comprehensive Cancer Network (NCCN)
American Society for Transplantation and Cellular Therapy (ASTCT)

These organizations provide guidance on neutropenic precautions, vaccination, antimicrobial prophylaxis and treatment, and IV immunoglobulin (IVIG) use, particularly with newer immunotherapies. The 2026 CJON review provides a table of prophylaxis recommendations for CAR T-cell therapy and BiTEs.2

What About Preventive Strategies Such as Vaccines and IVIG?

Vaccination remains a cornerstone of infection prevention and should occur early in the disease course or during a remission when possible. Oncology nurses can:

Review hepatitis B and C and HIV screening, especially before SCT, CAR T-cell therapy, or BiTE therapy
Recommend inactivated vaccines—including pneumococcal, influenza, COVID-19, and recombinant zoster—for all patients, along with the RSV vaccine for patients older than 60 years
Reinforce vaccination as a priority because infection risk may persist after treatment, particularly with more intensive therapy
Coordinate care with referring clinicians to promote adherence to vaccine schedules
Educate patients and caregivers that household members and close contacts should remain current with vaccines

BCMA-targeted therapy can cause prolonged hypogammaglobulinemia. Recent studies suggest a benefit of providing prophylactic IVIG rather than waiting to administer it for severe hypogammaglobulinemia or recurrent infections.4

What Are the Oncology Nursing Implications?

Because patients with MM can present with masked warning signs of infection, oncology nurses should suspect infection even with mild or nonspecific symptoms. Assess patients for:

New or worsening fatigue, malaise, or declining functional status
Low-grade fever, which may be clinically significant in patients with neutropenia or immunosuppression
New or worsening respiratory symptoms
New localized symptoms, especially around a central line
Urinary symptoms such as dysuria, frequency, or new flank or back pain

Patients and caregivers may notice subtle changes before obvious signs of infection develop.

Oncology nurses have a critical role in recognizing these changes, rapidly triaging symptoms, and facilitating prompt evaluation and treatment.5 Patients and caregivers need to know when and how to reach the healthcare team (including after hours) because infection can progress rapidly in patients with neutropenia or immunosuppression.