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O’Brien MM, Lacayo NJ, Lum BL, Kshirsagar S, Buck S, Ravindranath Y, Bernstein M, Weinstein H, Chang MN, Arceci RJ, Sikic BI, Dahl GV. Phase I study of valspodar (PSC-833) with mitoxantrone and etoposide in refractory and relapsed pediatric acute leukemia: a report from the Children's Oncology Group. Pediatr Blood Cancer 2010; 54:694-702. [PMID: 20209646 PMCID: PMC2838930 DOI: 10.1002/pbc.22366] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND Valspodar, a non-immunosuppressive analog of cylosporine, is a potent P-glycoprotein (MDR1) inhibitor. As MDR1-mediated efflux of chemotherapeutic agents from leukemic blasts may contribute to drug resistance, a phase 1 study of valspodar combined with mitoxantrone and etoposide in pediatric patients with relapsed or refractory leukemias was performed. PROCEDURE Patients received a valspodar-loading dose (2 mg/kg) followed by a 5-day continuous valspodar infusion (8, 10, 12.5, or 15 mg/kg/day) combined with lower than standard doses of mitoxantrone and etoposide. The valspodar dose was escalated using a standard 3 + 3 phase I design. RESULTS Twenty-one patients were evaluable for toxicity and 20 for response. The maximum tolerated dose (MTD) of valspodar was 12.5 mg/kg/day, combined with 50% dose-reduced mitoxantrone and etoposide. The clearance of mitoxantrone and etoposide was decreased by 64% and 60%, respectively, when combined with valspodar. Dose-limiting toxicities included stomatitis, ataxia, and bone marrow aplasia. Three of 11 patients with acute lymphoblastic leukemia (ALL) had complete responses while no patient with acute myeloid leukemia (AML) had an objective response. In vitro studies demonstrated P-glycoprotein expression on the blasts of 5 of 14 patients, although only 1 had inhibition of rhodamine efflux by valspodar. CONCLUSIONS While this regimen was tolerable, responses in this heavily pretreated population were limited to a subset of patients with ALL.
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Affiliation(s)
- Maureen M. O’Brien
- Department of Pediatrics, Division of Hematology/Oncology, Stanford University School of Medicine, Stanford, CA
| | - Norman J. Lacayo
- Department of Pediatrics, Division of Hematology/Oncology, Stanford University School of Medicine, Stanford, CA
| | - Bert L. Lum
- Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford, CA
,Department of Medicine, Division of Clinical Pharmacology, Stanford University School of Medicine, Stanford, CA
| | - Smita Kshirsagar
- Department of Medicine, Division of Clinical Pharmacology, Stanford University School of Medicine, Stanford, CA
| | - Steven Buck
- Children’s Hospital of Michigan, Detroit, MI
| | | | | | | | | | - Robert J. Arceci
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD
| | - Branimir I. Sikic
- Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford, CA
,Department of Medicine, Division of Clinical Pharmacology, Stanford University School of Medicine, Stanford, CA
| | - Gary V. Dahl
- Department of Pediatrics, Division of Hematology/Oncology, Stanford University School of Medicine, Stanford, CA
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