Phase I/II study of the P-glycoprotein modulator PSC 833 in patients with acute myeloid leukemia.
OBJECTIVE
To determine the maximum-tolerated dose, pharmacokinetic interaction, and activity of PSC 833 compared with daunorubicin (DNR) and cytarabine in patients with poor-risk acute myeloid leukemia.


METHODS
Patients received ara-C 3 g/m(2)/d on 5 consecutive days, followed by an IV loading dose of PSC 833 (1.5 mg/kg) and an 84-hour continuous infusion escalating from 6, 9, or 10 mg/kg/d. Daunorubicin was administered as a 72-hour continuous infusion at 34 or 45 mg/m2/d [corrected]. Responding patients received consolidation chemotherapy with DNR pharmacokinetics performed without PSC-833 on day 1, and with PSC-833 on day 4. Response was correlated with expression of P-glycoprotein and lung resistance protein (LRP), and in vitro sensitization of leukemia progenitors to DNR cytotoxicity by PSC 833.


RESULTS
All 43 patients are assessable for toxicity and response. Grade 3 or greater hyperbilirubinemia (70%) was the only dose-dependent toxicity. Four patients (9%) succumbed to treatment-related complications. Twenty-one patients (49%) achieved a complete remission or restored chronic phase, including 10 of 20 patients treated at the maximum-tolerated dose of 10 mg/kg/d of PSC-833 and 45 mg/m(2) of DNR. The 95% confidence interval for complete response was 33.9% to 63.7%. Administration of PSC 833 did not alter the mean area under the curve for DNR, although clearance decreased approximately two-fold (P =.04). Daunorubicinol clearance decreased 3.3-fold (P =.016). Remission rates were not effected by mdr-1 expression, but LRP overexpression was associated with chemotherapy resistance.


CONCLUSIONS
Combined treatment with infused PSC 833 and DNR is well tolerated and has activity in patients with poor risk acute myeloid leukemia. Administration of PSC 833 delays elimination of daunorubicinol, but yields variable changes in DNR systemic exposure.
Section of Hematology/Oncology and Bone Marrow Transplantation Program, Arizona Cancer Center, Tucson 85724-5024, USA.
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Dorr
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Karanes
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Spier
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Grogan
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Greer
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Moore
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Weinberger
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Schiller
T
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Pearce
M
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Litchman
W
W
Dalton
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D
Roe
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List
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D019540:Area Under Curve; D003524:Cyclosporins / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D003561:Cytarabine / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D003630:Daunorubicin / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007951:Leukemia, Myeloid / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016896:Treatment Outcome
D003524:Cyclosporins; D003561:Cytarabine; C070272:valspodar; D003630:Daunorubicin