Study of IgPro20 to Prevent Infection in People With Multiple Myeloma and Hypogammaglobulinemia

This study is testing whether a medication called IgPro20 (a type of antibody infusion given under the skin) can help prevent infections in people with multiple myeloma who have low antibody levels and are being treated with a newer type of drug called a bispecific antibody. **You may be eligible if...** - You have relapsed or refractory multiple myeloma (cancer that has come back or stopped responding to treatment) - You are currently receiving a commercially available bispecific antibody and have completed 1 to 4 treatment cycles - You are 18 or older - You are in reasonably good health with a life expectancy greater than 12 months **You may NOT be eligible if...** - You had a stem cell transplant in the last 3 months - You are planning CAR-T therapy in the next 6 months - You have had more than one serious deep-seated infection in the past 3 months - You have HIV, active hepatitis B or C - You are pregnant - You have very low white blood cell or platelet counts - You have had a stroke or brain bleed in the last 6 months - You have severe kidney disease (creatinine clearance below 30) - You are currently on or recently used IV immunoglobulin (IVIG) - You have a known allergy to IgG products Talk to your doctor to see if this trial is right for you.