Pneumocystis Carinii Pneumonia As a Complication of Bendamustine Monotherapy in a Patient with Advanced Progressive Breast Cancer

Background: Bendamustine is an alkylator with anticipated antimetabolic activity. It has shown activity in malignant lymphoma, multiple myeloma, and breast cancer. Recognized side-effects are relatively mild with myelosuppression as the dose-limiting toxicity. The CD4/CD8 ratio may be reduced. To what extent the alteration of lymphocytes, especially CD4(+) lymphocytes, correlates with an increase in opportunistic infections cannot be definitively answered.

Case Report: The patient, female, aged 48 years, was suffering from an advanced progressive breast cancer. After initial treatment with several chemotherapies, a cytotoxic therapy was initiated, with bendamustine (150 mg/m(2)) administered on two consecutive days and repeated every 4 weeks. After five courses, the patient developed Pneumocystis carinii pneumonia (PCP), disclosed in the bronchoalveolar lavage. While receiving bendamustine therapy, the CD4(+) and CD8(+) lymphocyte counts in the peripheral blood were determined by flow cytometry. The next-to-normal CD4/CD8 ratio before therapy (0,82) had decreased to 0,05 during the therapy mainly due to a decline of CD4(+) lymphocyte. The patient was seronegative for human immunodeficiency virus. In spite of high-dose intravenous trimethoprim/sulfamethoxazole and methylprednisolone application, the patient died of a respiratory failure 3 days after PCP was diagnosed.

Conclusion: Bendamustine is capable of inducing a reduction in CD4(+) lymphocyte counts causing a severe T-lymphocyte-mediated immunosuppression. Measuring CD4(+) lymphocyte counts may be helpful in determining the risk of PCP in patients treated with bendamustine.