Lymphocyte function following radium-223 therapy in patients with metastasized, castration-resistant prostate cancer

Therapy with the alpha-emitter radium-223 chloride (Ra-223) is an innovative therapeutic option in patients with metastasized, castration-resistant prostate cancer. However, radiotherapy can lead to hematopoietic toxicity. The aim of this study was to determine if Ra-223 therapy induces an impairment of cellular antimicrobial immune responses. In 11 patients receiving Ra-223 treatment, lymphocyte proliferation and the production of pro- and anti-inflammatory cytokines (interferon-gamma and interleukin-10) were determined, using lymphocyte transformation testing and ELISpot, respectively. Lymphocyte function after stimulation with mitogens and microbial antigens was assessed prior to therapy and at day 1, 7 and 28 after therapy. Lymphocyte proliferation and the production of interferon-gamma and interleukin-10 towards mitogens and antigens remained unchanged after therapy. Consistent with these in vitro data, we did not observe infectious complications after treatment. The results argue against an impairment of lymphocyte function after Ra-223 therapy. Thus, immune responses against pathogens should remain unaffected.