Exploring hidden risk: The prevalence of humoral immunodeficiency in patients with lymphoproliferative disorders—A prospective study.

e19083 Background: Infection is a significant cause of morbidity & mortality in patients with chronic lymphocytic leukemia (CLL), lymphoma, & multiple myeloma (MM). As evaluation for immunodeficiency is heterogeneous, we conducted a study to proactively assess humoral function. Methods: We enrolled 91 patients with CLL, lymphoma, or MM, all ≥18 years of age. Patients were excluded if they had undergone a transplant within 6 months or had known immunodeficiency. Patients were evaluated by checking immunoglobulin (Ig) levels & response to pneumococcal (PPV23) & tetanus-diphtheria vaccines. Immunodeficiency was defined by hypogammaglobinemia + suboptimal response to vaccination. Patients with an abnormal immune evaluation were offered revaccination, prophylactic antibiotics, or Ig replacement therapy. Data collected included demographics, diagnosis, comorbidities, prior treatments, and infections. Results: Ninety-one patients were included. The average age was 69.5 years, and 40 (44%) were females. Thirty-five patients had MM, 42 had lymphoma, and 14 had CLL. Fifteen (16.5%) were being managed with active surveillance (8 CLL, 7 lymphoma). The median number of prior lines of therapy was 1 (Range 0-6). 29 (31.9%) patients had abnormal immune evaluations with 20 (57.1%) MM patients, 4 (28.6%) CLL patients, and 5 (11.9%) lymphoma patients. At least one Ig class was low in 63 (69.2%) patients, with IgG being low in 41 (45.1%). Of the 29 patients with an abnormal evaluation, 6 received revaccination with pneumococcal vaccines and 5 started Ig replacement. During the follow up period, 29 patients experienced 40 infections, with 14 requiring hospitalizations. The most common infections were pneumonia (13), urinary tract infection (6), and cellulitis (5). Kaplan-Meier analysis was performed from the date of cancer diagnosis to the diagnosis of immunodeficiency for CLL, MM, & lymphoma. The analysis revealed significant differences in prevalence of immunodeficiency between the three cancer types (p=0.009). Pairwise testing revealed (type I error rate 0.05/3) MM patients had immunodeficiency at a higher rate than lymphoma patients (p=0.010). However, no statistically significant difference was found between CLL & Lymphoma (p=0.63) or between CLL & MM (p=0.034). Conclusions: Our study demonstrated that 31.9% of patients with CLL, MM & lymphoma have humoral immunodeficiency. Notably, MM patients were at the highest risk, with a statistically significant difference observed between MM and lymphoma. These findings underscore the need for routine immune screening & timely interventions to avoid complications in this high-risk population.