Serum immunoglobulin G as a discriminator of infection in follicular lymphoma patients undergoing chemotherapy with bendamustine in combination with rituximab

Objectives: Chemotherapy, including bendamustine, usually causes lymphocytopaenia and hypogammaglobulinaemia as side effects in patients with haematological malignancies. Therefore, the possibility has been considered that these immunological adverse events induced by bendamustine may lead to infectious diseases. However, lymphocytopaenia and/or hypogammaglobulinaemia have not yet been shown to have a statistically significant association with infection in cancer patients who receive bendamustine. Methods: We retrospectively studied 27 patients with relapsed or refractory indolent follicular lymphoma who were treated with bendamustine and rituximab (BR). In order to elucidate relationships between immune-related laboratory parameters (i.e. peripheral blood leukocyte, neutrophil, lymphocyte and immunoglobulin G [IgG]) and infectious events, receiver operating characteristic (ROC) curve and multivariate logistic regression analyses were performed. Results: Infectious diseases occurred in 11 patients (11/27, 41%), including 3 (3/27, 11%) with severe diseases. The area under the ROC curve (AUC) showed that the lowest IgG level during and after BR discriminated infectious events (cut-off value, 603 mg/dL) with 81.8% sensitivity and 68.8% specificity (AUC, 0.76; 95% CI, 0.52-0.90). Furthermore, a multivariate regression analysis revealed that the minimal serum IgG value during and after BR therapy was the only variable that was significantly associated with infection (odds ratio, 8.29; 95% CI, 1.19-57.62; p value, 0.03). Conclusion: Serum IgG ≤603 mg/dL during and after BR therapy was independently associated with an increased risk of infection. The monitoring of serum IgG during chemotherapy may help to predict the development of infection in blood cancer patients undergoing chemotherapy with bendamustine in combination with rituximab.