Pneumocystis carinii pneumonia as a complication of bendamustine monotherapy in a patient with advanced progressive breast cancer

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.

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/m²) 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.

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.