This study was performed to investigate hematotoxicity and occurrence of PPE in patients with high-grade non-Hodgkins lymphoma treated with a modified CHOP regimen (CLAOP), where doxorubicin had been substituted by a noncardiotoxic pegliposomal doxorubicin. An open-label phase I/IIa study was performed evaluating CLAOP21/20 with 20 mg/m(2) of pegliposomal doxorubicin every 21 days (12 patients), and a dose-dense filgrastim supported CLAOP14 regimen every 14 days with escalating doses of pegliposomal doxorubicin (24 patients) in elderly high-grade lymphoma patients or patients with comorbidity interfering with cardiac function. CLAOP21/20 was well tolerated. Hematotoxicity was similar to that reported with regular CHOP. In the CLAOP14 cohort, a pegliposomal doxorubicin dose of 25 mg/m(2) was associated with dose-limiting hematotoxicity, febrile episodes, and PPE. Both regimens were active with an overall response rate of 60% and 77%, respectively. The recommended dose of pegliposomal doxorubicin in the biweekly regimen for Phase II/III testing is 20 mg/m(2).