Advances in Brief
Feasibility and Correlates of Arsenic Trioxide Combined with
Ascorbic Acid-mediated Depletion of Intracellular Glutathione
for the Treatment of Relapsed/Refractory
Multiple Myeloma
1
Nizar J. Bahlis,
2
Jennifer McCafferty-Grad,
Ileana Jordan-McMurry, Jim Neil, Isildinha Reis,
Mohamed Kharfan-Dabaja,
3
James Eckman,
Mark Goodman, Hugo F. Fernandez,
Lawrence H. Boise, and Kelvin P. Lee
4
Sylvester Comprehensive Cancer Center [N. J. B., J. M-G., I. J-M.,
I. R., M. K-D., M. G., H. F. F., L. H. B., K. P. L.], Division of
Hematology and Oncology, Department of Medicine [N. J. B.,
M. K-D., M. G., H. F. F., K. P. L.], and Department of Microbiology
and Immunology [J. M-G., L. H. B., K. P. L.], University of Miami,
Florida, and Division of Hematology and Oncology, Department of
Medicine, Grady Memorial Hospital, Emory University, Atlanta,
Georgia [J. N., J. E.]
Abstract
Patients with multiple myeloma (MM) invariably re-
lapse with chemotherapy-resistant disease, underscoring the
need for new agents that bypass these resistance mecha-
nisms. We have reported that ascorbic acid (AA) enhances
the activity of arsenic trioxide (As
2
0
3
) against drug-resistant
MM in vitro by depleting intracellular glutathione (GSH).
These data led us to open a National Cancer Institute/
Cancer Therapy Evaluation Program-sponsored Phase I/II
trial of As
2
0
3
AA for relapsed/refractory MM. We now
present the completed Phase I component of this trial. The
primary objective of the trial’s Phase I component was to
assess whether the addition of AA affected the well-
described toxicity profile of As
2
0
3
alone. Correlative studies
were undertaken of As
2
0
3
and AA pharmacokinetics, the
ability of AA to deplete intracellular GSH in vivo, and the
development of arsenic resistance. Six patients with stage
IIIA relapsed/refractory myeloma were studied. We found
that 0.25 mg/kg/day As
2
O
3
1000 mg/day AA could be
given for 25 days (over a 35-day period) without dose-
limiting toxicity. One episode of grade 3 hematological tox-
icity (leukopenia) and no grade 3 nonhematological toxicities
(in particular, cardiac) were observed. The coadministration
of AA did not alter the pharmacokinetics of As
2
0
3
, and
elevated AA levels were associated with decreased intracel-
lular GSH. Serial in vitro studies demonstrated continued
sensitivity of patient myeloma cells to As
2
0
3
AA. Two
patients (both with thalidomide-refractory disease) had par-
tial responses; four patients had stable disease. In conclu-
sion, we have found that As
2
0
3
AA has acceptable toxicity
and that there is promising evidence of activity in refrac-
tory/relapsed myeloma.
Introduction
MM
5
remains an incurable disease with an overall 5-year
survival of less than 30% (1). Even with intensive up-front
treatment strategies with stem cell rescue, the majority of pa-
tients with MM eventually relapse with chemotherapy-resistant
disease (2, 3). A major mechanism of multidrug resistance is
overexpression of the mdr1 and mrp genes (4, 5). These drug
efflux pumps protect the MM cell by preventing the intracellular
accumulation of a wide range of chemotherapeutic agents. Pro-
survival cytokines (interleukin 6, tumor necrosis factor , vas-
cular endothelial growth factor), stromal interactions, enhanced
drug metabolism via the GSH redox pathway, alterations in drug
targets (topoisomerase II enzyme mutations, tubulin gene mu-
tation, glucocorticoid receptor down-regulation), and up-regu-
lation of antiapoptotic genes (Bcl-2, Bcl-x
L
, Mcl-1) have also
been reported as chemoresistant mechanisms in MM (6 –10).
Median survival for chemoresistant relapsed/refractory
MM is predictably short, in the order of months (6). Chemo-
therapy regimens for refractory and relapsed MM (e.g., VAD in
melphalan-resistant disease, high-dose steroids, IFN-, cyclo-
phosphamide + topotecan, and so forth) typically have 10 –30%
response rates of short duration (11). The failure of “traditional”
chemotherapy in relapsed and refractory MM is the rationale for
testing novel agents that may act via unique tumoricidal mech-
Received 4/1/02; revised 7/17/02; accepted 8/1/02.
The costs of publication of this article were defrayed in part by the
payment of page charges. This article must therefore be hereby marked
advertisement in accordance with 18 U.S.C. Section 1734 solely to
indicate this fact.
1
Supported in part by Senior Research Grant from the Multiple My-
eloma Research Foundation (to L. H. B.), an American Society of Clin-
ical Oncology (ASCO) Young Investigator Award (to N. J. B.), an
American Institute of Cancer Research fellowship (to J. M-G.), and the
Sylvester Comprehensive Cancer Center Developmental Award (to
K. P. L. and L. H. B.) and Postdoctoral Fellowship Award (to N. J. B.).
2
Present address: Division of Hematology and Oncology, Department
of Medicine, Case Western Reserve University, Cleveland, OH 44106.
3
Present address: Section of Hematology and Oncology, Department of
Medicine, University of Oklahoma Health Sciences Center, Oklahoma
City, OK 73104.
4
To whom requests for reprints should be addressed, at Papanicolaou
Building, Room 211, 1550 10th NW Avenue, Miami, FL 33156. E-mail:
Klee@med.miami.edu.
5
The abbreviations used are: MM, multiple myeloma; NCI, National
Cancer Institute; CR, complete remission; APL, acute promyelocytic
leukemia; ROS, reactive oxygen species; GSH, glutathione; AA, ascor-
bic acid; BSO, buthionine sulfoximine; DLT, dose-limiting toxicity;
CTEP, Cancer Therapy Evaluation Program; PR, partial response;
PBMC, peripheral blood mononuclear cell; EKG, electrocardiogram.
3658 Vol. 8, 3658 –3668, December 2002 Clinical Cancer Research
Research.
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