Phase I dose-escalation study of EZN-2208 (PEG-SN38), a novel conjugate of poly(ethylene) glycol and SN38, administered weekly in patients with advanced cancer
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This study evaluated the tolerability, pharmacokinetics, and preliminary antitumor activity of EZN-2208, a water-soluble poly(ethylene) glycol conjugate of SN38.
Patients with advanced malignancies were enrolled in dose-escalating cohorts (3 + 3 design). EZN-2208 was administered as a 1-h intravenous infusion given weekly for 3 weeks per each 4-week cycle. Doses ranged from 1 to 12 mg/m2.
Forty-one patients received EZN-2208. All patients had received prior cancer therapy (median = 2, range = 1–11). Twenty patients (49 %) had received prior irinotecan, and one patient had received prior topotecan. One patient in the 9-mg/m2 cohort had dose-limiting toxicity (grade 3 febrile neutropenia), and one patient in the 12-mg/m2 cohort had grade 3 neutropenia that resulted in the inability to deliver the third dose of EZN-2208. The most commonly reported drug-related adverse events were nausea (51 %), diarrhea (46 %), fatigue (41 %), alopecia (29 %), neutropenia (24 %), and vomiting (22 %). Administration of EZN-2208 results in prolonged exposure to SN38. Stable disease, sometimes prolonged, was observed as best response.
EZN-2208 has an acceptable safety profile in previously treated patients with advanced malignancies. The recommended phase II dose of EZN-2208 administered according to this schedule was 9 mg/m2.
KeywordsTopoisomerase-1 inhibitors SN38 Polyethylene glycol Phase I clinical trials
The authors thank Arlene Reiss and Hana Fainman (consultant medical writers for Enzon) for their assistance in the manuscript preparation.
Conflict of interest
Employment and Stock Ownership: Aby Buchbinder, Enzon; Advisory Role: Anthony Tolcher (Uncompensated); Honoraria: François Lokiec, Keyvan Rezaï, Saïk Urien; Research Funding: Muralidhar Beeram, Kyriakos Papadopoulos, Amita Patnaik, Anthony Tolcher.
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