Phase I Trial of Cremophor EL with Bolus Doxorubicin · mUm2 cremophor reached plasma levels 1.5 ilJml, but at 60 mI/rn2, only two of four reached this level, and the cal-culated
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Vol. 4, 2321-2329, October 1998 Clinical Cancer Research 2321
Phase I Trial of Cremophor EL with Bolus Doxorubicin
Michael J. Millward,’ Lorraine K. Webster,
Danny Rischin, Kerrie H. Stokes, Guy C. Toner,
James F. Bishop, Ian N. Olver,
Bernadette M. Linahan, Martha E. Linsenmeyer,
and David M. WoodcockDivision of Hematology and Medical Oncology [M. J. M., D. R.,G. C. T.. J. F. B., I. N. 0.], Pharmacology and DevelopmentalTherapeutics Unit [M. J. M., L. K. W., K. S., B. M. L.], Molecular
Genetics Laboratory [M. E. L., D. M. W.], Peter MacCallum Cancer
Institute, Melbourne 3000, Australia
ABSTRACT
Cremophor EL (cremophor), a component of the pacli-
taxel formulation, can potentially reverse P-glycoprotein-associated multidrug resistance. A Phase I trial of cremo-phor as a 6-h infusion every 3 weeks was performed withbolus doxorubicin (50 mg/m2). The cremophor dose wasescalated from 1 to 60 mI/rn2. A standard paclitaxel premed-ication was given before cremophor. Using a bioassay, p0-
tentially active cremophor levels (�1 �il/ml) were measured
in plasma from patients receiving cremophor doses of 30, 45,and 60 mum2. A cross-over design was used to assess the
influence of cremophor 30 mI/rn2 on the pharmacokinetics of
doxorubicin and doxorubicinol. The plasma area under the
concentration versus time curve (AUC) of doxorubicin in-
creased from 1448 ± 350 to 1786 ± 264 nglmlh (P = 0.02)
in the presence of cremophor, whereas the AUC of doxoru-
bicinol increased from 252 ± 104 to 486 ± 107 ng/mlh (P =
0.02). This pharmacokinetic interaction was associated with
significantly increased neutropenia. With reduction of the
doxorubicin dose to 35 mg/rn2, the cremophor dose was
increased to 60 ml/m2. Dose-limiting toxicities occurred in
two of six patients after 45 mum2 and two of four patients
after 60 mI/rn2, which included febrile neutropenia andgrade HI cremophor-related toxicities of rash, pruritus,headache, and hypotension. All patients who received 45
mUm2 cremophor reached plasma levels �1.5 �ilJml, but at60 mI/rn2, only two of four reached this level, and the cal-culated plasma clearance of cremophor was significantly
faster at this dose. One patient with hepatoma resistant to
epirubicin achieved a near-complete response. Cremophor
45 mI/rn2 over 6 h with 35 mg/rn2 doxorubicin is recom-mended for further studies. The pharmacokinetic interac-
Received 1/23/98; revised 7/9/98; accepted 7/10/98.
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.
I To whom requests for reprints should be addressed, at Sydney Cancer
Centre. Royal Prince Alfred Hospital, Sydney 2050, Australia. Phone:
because of unwillingness to participate in the pharmacokinetic
studies.
Toxicity. Hernatological toxicity was evaluated with the
combination of doxorubicin and cremophor following 74 cycles
in 39 patients. One patient at level 4A could not be evaluated
because of a lack of nadir counts. Another eight cycles were not
evaluated because the doxorubicin dose was reduced after he-
matological toxicity in previous cycles.
The principal hematological toxicity was neutropenia. The
incidence of grade IV neutropenia increased with increasing
cremophor doses. Grade IV neutropenia occurred in 0 of 3
patients at level 1, 1 of 4 patients at level 2, 4 of 6 patients at
level 3, and 1 1 of 16 patients at levels 4 and 4A. With the
reduction of doxorubicin dose, grade IV neutropenia occurred in
I of 6 patients at level 5 and 2 of 4 patients at level 6. Febrile
neutropenia occurred in one patient at level 3, three patients at
levels 4 and 4A, one patient at level 5, and one patient at level
6. There was one death at level 4 from neutropenic sepsis.
Thrombocytopenia was rare, with two patients having grade IV
thrombocytopenia (one at level 4A and one at level 6), both in
the setting of febrile neutropenia. One patient at level 4A had
grade IV anemia.
In six patients at level 4A, neutropenia could be evaluated
in the first two cycles in the presence and absence of cremophor.
All these patients received 50 mg/rn2 doxorubicin. The mean
neutrophil nadir was 1.9 X 109/liter after doxorubicin alone and
0.58 X l09fliter after doxorubicin with cremophor (P = 0.03;
Fig. la). Three patients at level 5 and three patients at level 6
had neutropenia evaluated in the first two cycles. These patients
received 50 mg/rn2 doxorubicin alone and 35 mg/rn2 with crc-
mophor. The mean neutrophil nadir was 1.7 X lO9Iliter after
Fig. I Nadir absolute neutrophil count (ANC) in patients receivingeither doxorubicin (Dox) alone or doxorubicin with cremophor. Eachpair of points represents an individual patient. a, patients receiving 50
mg/m2 doxorubicin alone or the same dose with 30 mUm2 cremophor. b,
patients receiving 50 mg/m2 doxorubicin alone or 35 mg/rn2 doxorubi-
cm with cremophor 45 mI/rn2 (-) or 60 mI/rn2 (----).
doxorubicin alone and 1.4 X 109/Iiter after doxorubicin with
cremophor (P = 0. 16; Fig. lb).
Other doxorubicin-related toxicity was infrequent. Stoma-
titis was recorded in 12 patients, but only 2 reached grade III
(one patient at level 4A and one at level 5). Only three patients
received five or more cycles of doxorubicin with cremophor.
One patient at level 4 developed angina after eight cycles. This
patient had previously documented ischemic heart disease and
had undergone a coronary angioplasty. His prestudy left yen-
tricular ejection fraction was 6 1%; after six cycles of doxoru-
bicin and 30 ml/m2 crernophor, it was 56%, and after eight
cycles, it had fallen to 43% with global dysfunction, indicating
anthracycline cardiotoxicity. After an additional angioplasty, the
angina resolved, but the ejection fraction did not improve. One
patient at dose level 1 received nine cycles of doxorubicin and
cremophor and one patient at level 5 received five cycles of
doxorubicin and cremophor plus one cycle of doxorubicin alone.
Neither of these patients had any fall in their ejection fraction.
No major hypersensitivity reactions to cremophor were
observed, and no patients had their infusion discontinued or
modified. Toxicities considered potentially related to crernophor
were cutaneous (pruritus, flushing, or rashes), hypotension or
dizziness, and headache. Because of the subjective nature of
some of these symptoms, they were graded as grade I (mild and
not requiring treatment or interfering with function), grade II
ng/mlth; P = 0.03). The metabolite ratio was 0.31 ± 0. 1 1 after
50 mg/m2 doxorubicin and 0.60 ± 0.22 after 35 mg/rn2 doxo-
rubicin with cremophor (P = 0.03).
DISCUSSION
In the initial clinical evaluation of compounds as potential
modulators of MDR, it is important to establish that adequate
amounts of the drug can be administered without producing
excessive normal tissue toxicity. The type of assay used in this
trial allows a more direct measurement of the desired biological
effect of the modulator than measurement of total or free plasma
drug levels and has been used by several groups investigating
new modulators such as PSC 833, S9788, and dexveraparnil (15,
34, 35). Although issues, including the standardization of such
assays, and the relationship between plasma and tumor bioassay
results require further investigation, a bioassay was particularly
appropriate for evaluating cremophor, because when this trial
was performed, the specific component of crernophor that pro-
duces MDR reversal had not been identified, and consequently
no specific assay for it was possible.
When given as a 6-h infusion, 45 mi/rn2 cremophor re-
sulted in plasma levels sufficient to potentially reverse P-gp-
mediated MDR in all patients. Although the limitations of the
bioassay do not allow definitive conclusions about the possible
nonlinear pharmacokinetics of the MDR-modulating compo-
nent(s) of cremophor to be drawn, the 45 mi/rn2 dose appears
most suitable for testing cremophor as a potential MDR modu-
lator in Phase II trials.
0 10 20 30 40 50
Time (hours)
Fig. 2 Plasma concentration-time curves for doxorubicin (circles) ordoxorubicinol (squares) in two representative patients receiving doxo-rubicin alone (open symbols) or with crernophor (closed symbols). A,
patient on dose level 4A, receiving 50 mg/rn2 doxorubicin alone or with30 mI/rn2 cremophor; B. patient on dose level 5, receiving 50 mg/rn2doxorubicin alone or 35 mg/m2 doxorubicin with 45 mI/rn2 cremophor.
Using the same assay, we have reported previously that in
the same patient population after 175 mg/rn2 paclitaxel over 3 or
6 h, the apparent half-life of crernophor was 26.1 ± 8.8 h and
26.4 ± 8.0 h, respectively (29). This is longer than found in this
Phase I study. It is possible that at the lower doses correspond-
ing to this paclitaxel dose, cremophor has a different pharma-
cokinetic behavior. It may also reflect that in the previous study
(29), cremophor levels were only measured up to a maximum of
24 h after completion of the paclitaxel infusion, whereas in this
study, more protracted sampling was undertaken. The present
study is therefore likely to have more accurate calculations of
the apparent half-life. It is also possible that when given corn-
bined with paclitaxel and ethanol, crernophor pharmacokinetics
are different than when cremophor is given alone.
In this trial, all patients were given a standard premedica-
tion schedule. No acute hypersensitivity reactions were ob-
served during cremophor infusions, but toxicities such as rash,
pruritus, and hypotension seen at the higher crernophor doses
are likely to be drug related. The cross-over design allows the
elimination of doxorubicin or the premedications themselves as
causative factors. It is possible that a more protracted regimen of
corticosteroids and/or antihistamines could reduce or prevent
these symptoms. One patient had persistent pruritus after crc-
mophor, a toxicity reported recently in 5 of 14 patients who
received high doses of paclitaxel (250-265 mg/rn2 over 3 h;
Ref. 36).
Although antitumor activity was not an end point of this
Phase I trial, two responses were observed in pretreated patients,
including an almost complete response in a patient with hepa-
torna previously resistant to anthracycline. Tumor biopsy for
P-gp expression was not required in this trial, but hepatomas are
known to express high levels of P-gp (37). This impressive
response demonstrates that additional studies of potential MDR
modulators such as cremophor in patients with hepatoma are
indicated.
A significant pharmacokinetic interaction between cremophor
and doxorubicin was demonstrated in this trial. When administered
with cremophor, the doxorubicin AUC increased by -30%. There
was an even greater increase in the AUC of doxorubicinol. We
have shown previously that in mice, cremophor produced a similar
pharmacokinetic interaction with doxorubicin and doxorubicinol
(38). This successful prediction shows the potential of such pre-
clinical studies to help design clinical trials with potential MDR
modulators. The pharmacodynamic end point of neutropenia was
measured and found to be significantly greater when doxorubicin
was given with cremophor.
The reason for this pharmacokinetic interaction could not
be determined from this trial. Doxorubicin is metabolized to
doxorubicinol by cytoplasmic aldoketoreductase enzymes, and
doxorubicinol is further metabolized to noncytotoxic aglycones
by microsornal P450 reductase. A similar effect to that observed
in this trial with cremophor has been reported when the MDR
modulator cyclosporin A was combined with doxorubicin (13).
Thus with cyclosporin A the doxorubicin AUC increased by
55%, and the doxorubicinol AUC increased by 350% with
increased neutropenia (1 3). In contrast, another trial showed
increased doxorubicin AUC but a lower then expected metab-
olite ratio (14) when doxorubicin and cyclosporin A were corn-
bined; however, patients were not evaluated after doxorubicin
alone (14). Pharmacokinetic interactions have also been re-
ported when doxorubicin has been combined with other MDR
modulators (39, 40), as well as when other drugs primarily
metabolized in the liver such as etoposide and paclitaxel are
combined with MDR modulators (15, 41, 42). Generally, such
interactions are characterized by slower clearance of the cyto-
toxic agent and increased normal tissue toxicity. Direct inhibi-
tion of P-gp in liver, biliary tract, and kidney, inhibition of
metabolizing enzymes such as hepatic cytochrorne P450 sys-
tems, and alterations of protein binding of the cytotoxic agent
may occur as a result of combining the agent with an MDR
modulator. It is likely that the observed pharrnacokinetic inter-
actions reflect a combination of these effects and may be de-
pendent on the modulator and cytotoxic used and perhaps on the
dose and schedule of the cytotoxic agent.
The pharmacokinetic results found in this trial are of rel-
evance for the observed pharmacokinetic interaction between
paclitaxel and doxorubicin. When paclitaxel was given as a 24-h
infusion immediately before a 48-h infusion of doxorubicin, the
doxorubicin clearance was reduced by 30% (43). Gianni et a!.
(44) recently reported a series of pharmacokinetic studies of the
paclitaxel/doxorubicin doublet. When a 3-h infusion of pacli-
taxel was given immediately after bolus doxorubicin, the doxo-
rubicin AUC increased by up to 30%, and the doxorubicinol
AUC increased by up to 100% compared to when paclitaxel was
commenced 24 h after doxorubicin. At least for doxorubicinol,
the effect was more pronounced when the paclitaxel dose was
increased from 150 to 200 mg/rn2. Concurrent 3-h administra-
tion of doxorubicin and paclitaxel led to lower doxorubicin and
doxorubicinol AUCs than bolus doxorubicin followed by a 3-h
pacitaxel infusion (44). In another study where both drugs were
given by 72-h infusion, concurrent paclitaxel increased the
steady-state concentration of doxorubicin and doxorubicinol,
although only the latter was statistically significant (45). Over-
all, despite the different schedules of both drugs used, admin-
istration of paclitaxel reduces the clearance of doxorubicin and
to a greater extent doxorubicinol. Our results indicate this is at
least in part due to the crernophor in the paclitaxel formulation.
Because cremophor is not a pure substance, it is difficult to
develop as a pharmaceutical. Studies to identify the specific
component or components responsible for in vitro MDR rever-
sal (46, 47) and develop potentially more active analogues (48)
have shown some success. Additional clinical studies with crc-
mophor and subsequently with these agents are indicated to
develop this novel class of compounds. Other observed preclin-
ical effects of cremophor may also translate into worthwhile
clinical outcome (49).
ACKNOWLEDGMENTS
We thank the members of the nursing and pharmacy staff at thePeter MacCallum Cancer Institute for their contribution to this study, in
particular Carmel Morton, Ann Fennessy, Ann Woollett, Karen Tin-
nelly, Lisa Sheeran, Rosetta Maisano, Jill Davis, and Judy Bingham. We
also appreciate the thoughtful comments of Professor John Zalcberg on
the manuscript.
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