In subsequently conducted phase II trials, thrombocytopenia related to prior carboplatin and alkylating agent therapies has become a prominent toxicity, and neutropenia has been more severe than anticipated from phase I studies. The risk for both toxicities relates to the extent of prior myelosuppressive chemotherapy and to renal impairment. These toxicities can be managed through the identification of high-risk patients and implementation of appropriate prophylactic measures. Such measures include dose reductions or the use of hematopoietic growth factors. For patients with persistently low blood cell parameters, transfusion therapy remains a viable option.
Hematologic toxicities associated with topotecan therapy are noncumulative.
Consequently, once a dosing regimen is established, toxicity patterns are predictable. Pretreatment assessment of the nature and toxicities of prior therapy and renal function should assist the clinician in preventing complications caused by the myelosuppressive effects of topotecan therapy.