Activity of Oxaliplatin against Human Tumor Colony-forming ... · Colony-forming Units1 Eric...

Vol. 4, 1021-1029, April 1998 Clinical Cancer Research 1021

3 The abbreviations used are: dach, 1 ,2-diaminocyclohexane; 5-FU,

5-fluorouracil; 95% CI, 95% confidence interval.

Activity of Oxaliplatin against Human Tumor

Colony-forming Units1

Eric Raymond,2 Richard Lawrence,

Elzbieta Izbicka, Sandrine Faivre, and

Damel D. Von Hoff

Nordan Colon Cancer Research & Translational Research Laboratory,Institute for Drug Development, Cancer Therapy and ResearchCenter, San Antonio, Texas 78245

ABSTRACT

This study was conducted to identify tumor types war-

ranting Phase II clinical trials of oxaliplatin using the hu-

man tumor cloning assay. Oxaliplatin was tested at concen-

trations ranging from 0.5 to 50.0 �ig/ml in 1-h and 14-day

continuous exposures along with 1.4 pig/mi carboplatin and

0.2 �g/ml cisplatin for comparison. We defined in vitro

response as tumor growth inhibition >50% of control. In

the 1-h exposure schedule, in vitro responses were observed

in 9 of 116 (8%), 18 of 115 (16%), 38 of 103 (37%), and 7 of

13 (54%) tumor specimens at concentrations of0.5, 5.0, 10.0,

and 50.0 pg/mi oxaliplatin, respectively. In the 14-day ex-

posure schedule, in vitro responses were observed in 10 of

121 (8%), 37 of 121 (31%), 57 of 106 (54%), and 15 of 15

(100%) tumor specimens at concentrations of 0.5, 5.0, 10.0,

and 50.0 pig/mi oxaliplatin, respectively. Activity was ob-

served against colon cancer, non-small cell lung cancer,

gastric cancer, and melanoma colony-forming units. In both

cisplatin-resistant and cisplatin-sensitive tumors, the activ-

ity of oxaliplatin was concentration and time dependent. A

1-h exposure to 5.0 and 10.0 pg/mi oxaliplatin led to 7.4 and

23.4% in vitro responses, respectively, in specimens resistant

to 1-h exposure of 0.2 pig/mi cisplatin. Moreover, 1-h expo-

sures to 5.0 �ig/m1 and 10.0 �ig/ml oxaliplatin showed in vitro

antitumor responses in 10.2 and 24.3%, 17.2 and 34.5%,

10.0 and 20.0%, 6.7 and 16.7%, and 11.4 and 34.3% of

specimens resistant to 1.4 pig/mi carboplatin, 6.0 p.g/ml

5-fluorouracil, 3.0 pg/mi irinotecan, 10.0 pig/mI paclitaxel,

and 0.04 �ig/ml doxorubicin, respectively. The effect in those

drug-resistant specimens was improved when oxaliplatin

was used on the protracted exposure regimen. Our data

Received 9/12/97; revised 1/6/98;accepted 1/8/98.The costs of publication of this article were defrayed in part by the

payment of page charges. This article must therefore be hereby markedadvertisement in accordance with 18 U.S.C. Section 1734 solely to

indicate this fact.

I Supported in part by a grant from Sanofi Research (Great Valley, PA)

and the Cancer Therapy and Research Foundation of South Texas (SanAntonio, TX). E. R. was supported by a fellowship from the Associationpour la Recherche contre le Cancer.2 Present address and to whom requests for reprints should be addressed,at D#{233}partementde M#{233}decine,Institut Gustave-Roussy, 39, rue CamilleDesmoulins, 94805 Villejuif Cedex, France. Phone: 33 1 42 11 43 17;Fax: 33 1 42 11 52 17; e-mail: [email protected].

indicate that oxaliplatin is an active drug in vitro against a

large variety of human tumors. Both concentration and

duration of exposure are important factors for oxaliplatin

cytotoxicity. The broad spectrum of activity and the in vitro

activity against some tumors primarily resistant to conven-

tiona! anticancer drugs encourage further clinical investiga-

tions of oxaliplatin in patients with advanced cancer refrac-

tory to conventional chemotherapy.

INTRODUCTION

Of the new-generation platinum compounds that have been

evaluated, those with the dach3 carrier ligand have received the

most attention in recent years ( 1 ). Kidani et a!. (2, 3) were the

first to suggest that the spatial conformations of the dach carrier

ligand might affect the interactions of dach-platinum com-

pounds with DNA and, therefore, the cytotoxicity of these

compounds (2). From these compounds, oxaliplatin [trans-i-

dach; (lR,2R-diaminocyclohexane)oxalatop!atinumj was se-

lected based on its preclinical activity in a variety of tumor

xenografts (4-6), the absence of renal toxicity (7), and its mild

hematological toxicity in Phase I clinical trials (8). Although

oxaliplatin forms platinum-DNA adducts very slowly in vitro,

the kinetics of intracellular platinum-DNA adduct formation (1,

9, 10), the percentages of the different intrastrand adducts, and

the sites of DNA binding appear similar to those of cisplatin in

many respects (1). However, in spite of those similarities, dach-

platinum adducts are bulkier and more hydrophobic than cis-

diammine-platinum adducts and may be more effective at in-

hibiting DNA synthesis (1 1) and cell growth than cisplatin

adducts (12). In addition, monoadduct-to-diadduct conversion is

slower for dach-platinum adducts (13), presumably because the

N-Pt-N bond angle is more constrained for dach-p!atinum-DNA

adducts than for cis-diammine-platinum-DNA adducts (14, 15).

Finally, recent evidence suggests that the loss of mismatch

repair that may occur early in the acquisition of cis-diammine-

platinum resistance in several human cancers displays a strong

carrier ligand specificity for cis-diammine versus dach-platinum

adducts (16). Consistent with these molecular biology studies,

the National Cancer Institute cytotoxic screening in vitro

showed that the dach-platinum compounds, including oxalipla-

tin, can be identified as a separate family with a unique mech-

anism(s) of action and a lack of, or only partial, cross-resistance

with cis-diammine compounds (12).

In clinical trials, pharmacokinetic data revealed that after a

2-h iv. injection of 130 mg/rn2 oxaliplatin, peak plasma levels

of total and ultrafiltrable platinum were 5.1 ± 0.2 and 2.1 ± 0.2

p.g/ml, respectively (7). In those studies, oxaliplatin showed a

very large volume of distribution (330.1 ± 41.9 liters). Inter-

Research. on February 22, 2021. © 1998 American Association for Cancerclincancerres.aacrjournals.org Downloaded from

http://clincancerres.aacrjournals.org/

1022 Cytotoxicity of Oxaliplatin in Cloning Assay

estingly, oxaliplatin accumulated rapidly in cells. Pharmacoki-

netic studies showed that 2 h after injection, only 50% of

platinum remained in the plasma (about 67% bound to proteins

and 33% ultrafiltrable), and the drug progressively accumulated

in RBCs with a long terminal half-life close to that of erythro-

cytes (17). This partitioning of platinum in erythrocytes appears

to be unique for oxaliplatin (18, 19). Although some in vitro

studies have shown that most of the intraerythrocyte ultrafil-

trable platinum remains nonexchangeable, the biotransforma-

tion of oxaliplatin in erythrocytes remains not clearly under-

stood (1). As a result, oxaliplatin shall be considered as a

prodrug that requires biotransformation in solution. However,

clinical data were mainly reported as �i.g/ml platinum instead of

jig/ml oxaliplatin. Therefore, this may generate a discrepancy

between the concentrations of oxaliplatin required to achieve

significant antiproliferative effects in vitro and the achievable in

vivo concentrations. To date, clinical experiences were mainly

focused on patients with advanced colorectal cancer using ox-

aliplatin either in short-term (20, 21) or continuous chrono-

modulated infusion (22). In patients with colorectal cancer, the

overall response rates of oxaliplatin alone were 20% in first-line

chemotherapy (23) and 10% in patients treated previously with

5-FU (24). Moreover, the antitumor activity was increased when

oxaliplatin was combined with 5-FU with or without folinic acid

(21, 25) in a small but constant proportion of patients with

complete histological responses. Those data obtained in patients

with colon cancer, which is usually considered very resistant to

any conventional chemotherapy, including cisplatin, may war-

rant further clinical investigation of oxaliplatin in other tumor

types.

On the basis of the preclinical and pharmacokinetic data

available for the selection of relevant concentrations and sched-

ules, we investigated the antiproliferative effects of oxaliplatin

at concentrations ranging from 0.5 to 50.0 �i.g/ml against human

tumor colony-forming units in vitro. The aims of this study were

to identify tumor types with in vitro response for future Phase II

clinical trials and to determine the relative antiproliferative

effects of short-term versus prolonged exposure to oxaliplatin at

clinically relevant concentrations.

MATERIALS AND METHODS

Collection of Tumor Cells. After written informed con-

sent was obtained according to institutional guidelines, tumor

specimens (biopsies, bone marrow, pleural effusions, and asci-

tes) were collected by sterile standard techniques as part of

routine clinical procedures. Samples were collected and deliv-

ered within an average time of 4 h and were processed imme-

diately upon arrival in the laboratory. Internal controls indicated

that the viability of cells was maintained when samples were

processed within 3 days for solid specimens and 5 days for fluid

ones. Biopsies of solid tumors were stored in McCoy’s SA

medium (Life Technologies, Inc., Grand Island, NY) containing

10% newborn calf serum, 10 mrsi HEPES, 100 p.g/ml of peni-

cillin, and 90 p.g/ml streptomycin (all from Life Technologies,

Inc.) for transport to the laboratory. Preservative-free heparin

(10 units/mI; O’Neill, Johns, and Feldman, St. Louis, MO) was

added immediately after collection of fluids to prevent coagu-

lation. Solid specimens were minced and repeatedly passed

through metal sieves with 100 p.m mesh (EC Apparatus, St.

Petersburg, FL) to obtain a single-cell suspension. When nec-

essary, effusions were centrifuged at 1 50 X g for 5-7 mm and

passed through 25-gauge needles to obtain single-cell suspen-

sions. All specimens were washed twice in McCoy’s SA me-

dium containing 5% horse serum (Sigma Chemical Co.), 10%

heat-inactivated FCS (Hyclone, Logan, UT), 2 mrvt sodium

pyruvate, 2 mM glutamine, 90 units/ml penicillin, 90 �ig/ml

streptomycin, and 35 p.g/ml L-serine (all from Life Technolo-

gies, Inc.). The viability of cells (from 40 to 100%) was deter-

mined on a hemocytometer with trypan blue. Only viable cells

determined the final concentration of plated cells.

Drugs. Purified oxaliplatin provided by Debiopharm

S.A. (Lausanne, Switzerland) was diluted in water to create

concentrated stocks. Aliquots of each stock solution were stored

at -70#{176}Cand were thawed immediately before the experiment.

Four final concentrations of 0.5, 5, 10, and 50 �i.g/ml were tested

at both 1-h and continuous exposures. Because of the reproduc-

ible high cytotoxic activity, testing at 50.0 p.g/ml was discon-

tinued after 7 and I S samples at 1-h and 14-day continuous

exposure, respectively.

Oxaliplatin activity was also evaluated in tumor specimens

that showed resistance to a panel of clinically relevant cytotoxic

drugs. Drug concentrations were selected based on our previous

experience with these anticancer drugs in the cloning assay (26,

27). These drug concentrations were previously associated with

in vitro responses and, for some drugs, were predictive of

clinical responses in previously published studies (26, 27). For

comparison, specimens were exposed, along with oxaliplatin, to

1.4 p.g/ml carboplatin and 0.2 p.g/mI cisplatin at both 1-h and

14-day exposures. Furthermore, because of the potential clinical

applications, the cytotoxicity of 1-h and 14-day oxaliplatin

exposures were evaluated in specimens resistant to the follow-

ing concentrations and schedules: 1-h exposure to 6.0 p�g/ml

5-FU; 1-h exposure to 0.3, 1.5, and 3.0 pj.g/ml irinotecan (CPT-

1 1 ; 7-ethyl-10-[4-(piperidyl)- 1 -piperidyl]carbonyloxy-campto-

thecin); 1-h exposure to 0.25, 2.5, and 10.0 p.g/ml paclitaxel; 1-h

exposure to 0.04 p.g/ml doxorubicin; and 1-h exposure to 3.0

p.g/ml cyclophosphamide. The in vitro concentrations used in

this study correlate with achievable in vivo concentrations in

humans that were previously shown to be effective in animals

and/or in clinical trials against a large variety of human tumor

types, including those used in this study (26, 27).

Human Tumor Cloning Assay. The human tumor don-

ing assay was performed using the two-layer system described

by Hamburger and Salmon with several modifications (28).

Briefly, cells were suspended in 0.3% agar in enriched Con-

naught Medical Research Laboratories medium 1066 supple-

mented with 15% heat-inactivated horse serum, penicillin (100

units/ml), streptomycin (2 mg/ml), glutamine (2 mM), insulin (3

units/ml), asparagine (0.6 mg/mI), and HEPES buffer (2 mM).

For the continuous exposure, compounds were added directly to

the above mixture. Cells were plated in 35-mm Petri dishes in a

top layer of agar over an underlayer of agar to prevent growth of

fibroblasts. Three plates were prepared for each data point. The

plates were incubated at 37#{176}Cand were removed on day 14 for

counting of the colonies. For the 1-h exposure studies, the cells

were incubated with the compound for 1 h and then washed and

plated in the top layer of agar, just as was done for the contin-



CC

C

S

V

0

00.1<V

CC�0

uous-exposure studies. The number of colonies (defined as >50

cells) formed in the three compound-treated plates were com-

pared to the number of colonies formed in the three control

plates, and the percentage of colonies surviving at that concen-

tration of compound was calculated.

Quality Control. A test was defined as an experiment

performed on a unique tumor tissue sample that contained

untreated control, positive control, and three specified com-

pound concentration levels. A test having an average of 20 or

more colonies present on day 14 in the untreated control plates

and <30% survival in the positive control was considered

evaluable. To ensure the presence of an excellent single-cell

suspension, a positive control consisting of the cell toxin or-

thosodium vanadate at a concentration of 200 �i.g/ml was used.

For an experiment to be considered assessable, the orthosodium

vanadate had to produce less than 30% survival of colony-

forming units. Three untreated control plates also were set up on

day 0. On the day of culture reading there should have been

<30% survival of tumor colony-forming units in the positive

control plates. If there was no effect on colony formation, then

the single-cell suspension on day 0 was poor (because orthoso-

dium vanadate does not affect clumps), and the tumor sample

test was considered nonevaluable. The use of a positive control

has been shown to greatly increase the reproducibility of the

human tumor cloning assay (28). The results were expressed as

the percentage of survival of tumor colony-forming units for a

particular drug relative to its control. This quantity was calcu-

lated as the ratio between the mean number of colonies surviv-

ing in the drug-treated plates and the mean number of colonies

growing in control plates. Survival rates were expressed as

means and SD. A response was defined as growth of tumor

colony-forming units in treated plates that was �50% of that in

control plates (considered as a relevant antiproliferative effect).

The in vitro response rate was the ratio of the number of in vitro

responses among evaluable specimens and was expressed as

mean and 95% CI. A specimen was considered resistant to a

cytotoxic drug when the growth of tumor colony-forming units

in plates treated with the higher concentration of this drug was

�50% of that in control plates.

To date, most authors agree that a 30% in vitro response

rate may translate into responses in clinical trials. However, for

some tumor types that are typically very resistant to classical

antitumor agents, a 20% in vitro response rate may also be

expected to translate into clinical benefit in clinical trials.

Statistics. Head-to-head comparisons of duration of ex-

posure were made using Wilcoxon’s signed rank test. Compar-

isons of response rates between drugs were made with Fisher’s

exact test or the x2 test as appropriate. A two-sided P < 0.05

was considered to indicate statistical significance.

RESULTS

Antiproliferative Effect against Human Tumor Colony-

forming Units. As can be seen in Table 1, a total of 224 and

243 freshly explanted tumor specimens were exposed to oxali-

platin for 1 h and 14 days, respectively. Of these specimens, 1 16

(52%) and 121 (50%) specimens exposed to oxaliplatin for 1 h

and 14 days, respectively, were considered evaluable for in vitro

response. The major subgroups of tumors tested (and the num-

C0

C

C0

0

U

0

S0

CCC

S0

-C

C

CC00CC

C

CC

0.

CC

0

0

>

UCC

0

S0

CCC

C

-0

r�)--- ‘.0 -e’�-r�1--- ‘.0

� � 00 r� C � m rn ��‘�-,oo�--�o - C (��4 �0 �r�-

0� In � � � 00 � r’� N-

N r�i � m � N � � C r�- � � �lC r�4C C C’)��oo�-

rn � n rn �- �0 � r�i �0 N

�,-� ��r4CCC� �-�CN-‘�-‘�-‘(-�--‘

CI,�

r’�

� c-� - m � c�i �O � C ----- r�i mr�1

� �� -C ‘n--mS-’

-�-�-,--

-C r’�---N

� � _ � � N

� � C m m 00 N C r’� �

�o � rn � m - � �- oo 00

� -,-�rn � N-N r’� � C � C 00 C N

- � - C - C N N �0 00

� 0000C N � C C 00 _�N’-’N-’NIt�N’

C--CCCNC�O�

N

O�Lf�N00N---C�

� � N � N 0� N � 00-- - - N-

V�UUCCUU

no

C

C

C

C.

C

a0

S0

I-

Clinical Cancer Research 1023

8

V

00.1<V

V �

CU 0.

dOZC

V �

CU 0.

doZC

0

8

0

V0

.-

a� -�

.0

00

0 .�

-CU

U0

V

0a�

V�

Ct) 0

C .C

.2 �

CUV

U>., VCC

OCUn

.0-�

CO.-

VV

.5 8U

0�

V8.0 0

0 .�

0V�

0�

.9 �

.� I� .5

.� 0V

CC0CC

.0 .�



U


‘vu � - I hour

-. = . Continuous exposura

75 ::..:

.� .::. � p-O�W�O1 p-O.OO1

I: �0.50 5.00 10.00

Concentration, �tgImI

50.00

Fig. 1 Antiproliferative activity of short-term (1-h) versus prolonged(14-day) exposures of oxaliplatin against colony-forming units in vitro(28). Results areexpressed as means ± SD; two-sided Ps were obtainedwith the Wilcoxon signed rank test.

ber of evaluable specimens exposed for 1 h and 14 days) were

ovarian (19 and 22), colon (15 and 12), breast (14 and 18),

non-small cell lung (14 and 13), and renal cell (7 and 11)

carcinomas. As shown in Table 1 , both short-term and pro-

longed exposure of oxaliplatin had a concentration-dependent

effect on growth inhibition of human tumors.

For the 1-h exposure schedule, in vitro responses were

observed in 9 of 1 16 (8%; 95% CI, 4-14), 18 of 1 15 (16%; 95%

CI, 10-24), 38 of 103 (37%; 95% CI, 28-47), and 7 of 13

(54%; 95% CI, 25-81) evaluable specimens at concentrations

0.5, 5.0, 10.0, and 50.0 pg/ml, respectively (Table 1). Head-to-

head comparisons of survival showed clear concentration-

response effects in the 1-h exposures (P < 0.01). For this

schedule, relevant antiproliferative effects were observed at the

relatively high concentration of 10.0 p�g/ml in breast (43%; 95%

CI, 18-71), colon (33%; 95% CI, 12-62), and non-small cell

lung (31%; 95% CI, 9-61) cancers. Although the number of

samples is limited, in vitro responses were also observed in four

gastric carcinomas (100%; 95% CI, 40-100), four sarcomas

(67%; 95% CI, 22-96), and three melanomas (43%; 95% CI,

10-82). No relevant antiproliferative effects were observed

against ovarian cancer for concentrations below 50.0 pg/ml in

the 1-h exposure schedule.

For the 14-day continuous-exposure schedule, in vitro re-

sponses were observed in 10 of 121 (8%; 95% CI, 4-15), 37 of

121 (31%; 95% CI, 23-40), 57 of 106 (54%; 95% CI, 44-64),

and 15 of 15 (100%; 95% CI, 78-100) specimens at concentra-

tions of 0.5, 5.0, 10.0, and 50.0 p.g/ml, respectively (Table 1).

As previously observed in the 1 -h exposure schedule, head-to-

head comparison of percentage survival demonstrated concen-

tration-response effects in the continuous exposures (P < 0.01).

In continuous exposure, relevant antiproliferative effects were

observed at concentrations starting at 5.0 jig/mi in renal (45%;

95% CI, 17-77), colon (42%; 95% CI, 15-72), ovarian (27%;

95% CI, 1 1-50), and non-small cell lung (23%; 95% CI, 5-54)

carcinomas. In vitro responses were also observed in four mel-

anomas (80%; 95% CI, 28-99), three sarcomas (50%; 95% CI,

12-88), and two gastric carcinomas (50%; 95% CI, 7-93).

Effects of Short-Term Versus Prolonged Exposures.

Interestingly, whereas increased concentrations showed a lim-

ited increase in cytotoxicity, the longer duration of exposure was

Upper panel

(U�!-�gsoC

C

(U

(U

0

C

C0

C.)

75

Oxaliplatin

0.5�tgImI . ..,

U”

5�tgIml

�25

100

75

50

25

10�tg!ml . 50�tg!ml�

. � s-/i,,

�

Lower panel

(U

I

is so 75 1#{243}0

Short Exposure

Cisplatin 0.2�tgln�

� .

25 50 75 100

Short Exposure

0 iS 50 75 I#{212}O

Short Exposure

Carboplatk� 1.4�sgIn�

0 is so is i#{243}oShort Exposure

Fig. 2 Scattergrams of percentage survival following short-term versus

long-term exposures to several concentrations of oxaliplatin (Upperpanel) and cisplatin and carboplatin (Lower panel), respectively. Each

point represents data from one individual specimen. Points were drawnby calculating the percentage survival after exposure to a single drugconcentration given as short-term (X axis) and continuous exposures (Yaxis), respectively. Graphs are presented with the best-fitted linearregression (-) and the 95% CIs (- - - -) that show a strong tendency

for time-related cytotoxic effects with oxaliplatin (concentrations rang-

ing from 0.5 to 50 p.g/ml), whereas such time-related cytotoxic effects

are not observed with 0.2 p.g/ml cisplatin and 1.4 p.g/ml carboplatin.

effective in maximizing the antiproliferative effects of oxalipla-

tin. Data for direct head-to-head comparisons of the antiprolif-

erative effects of 1-h versus 14-day continuous exposure were

available in 84, 83, 73, and 11 specimens at concentrations of

0.5, 5.0, 10.0, and 50.0 jig/mi, respectively. In this study, the in

vitro response rates were significantly higher with 14-day ex-

posure to oxaliplatin as compared to 1-h exposure (P < 0.01).

At all concentrations tested, there were significantly higher

antiproliferative effects with continuous-exposure oxaliplatin




Table 2 In vitro antitumor effects of oxaliplatin in specimens showing primary resistance to classical anticancer drugs�’

Concentrations and times of exposureto the parent drugs

No. of responses to oxaliplatin:No. resistant specimens (% in vitro responses)

1-h exposure, �i.g/ml 14-day exposure, pig/mI

0.5 5.0 10.0 0.5 5.0 10.0

0.2 pig/rn! cisplatin-resistant

specimens1-h exposure 1:81 (1.2%) 6:81 (7.4%) 19:81 (23.4%) 6:89 (6.7%) 28:89 (31.5%) 46:89(51.7%)

14-day exposure 3:74 (4.0%) 9:74 (12.2%) 21:74 (28.4%) 5:109 (4.6%) 30:109 (27.5%) 57:109(52.3%)1.4 pig/mI carboplatin-resistant

specimens

1-h exposure 3:78 (3.8%) 8:78 (10.2%) 19:78 (24.3%) 5:76 (6.6%) 25:76 (32.0%) 42:76 (55.3%)

14-day exposure 2:72 (2.8%) 6:72 (8.3%) 18:72 (25.0%) 3:109 (2.7%) 30:109 (27.5%) 56:109(51.4%)

6.0 pig/mi 5-Hi-resistant specimensI-h exposure 3:29 (10.3%) 5:29 (17.2%) 10:29 (34.5%) 4:38 (10.5%) 8:38 (21.0%) 21:38 (55.3%)

3.0 pig/mI irinotecan-resistantspecimens

1-h exposure 0:10 (0.0%) 1:10 (10.0%) 2:10 (20.0%) 1:17 (5.9%) 2:17 (1 1.8%) 8:17 (47.0%)10.0 pig/mI paclitaxel-resistant

specimens1-h exposure 0:30 (0.0%) 2:30 (6.7%) 5:30 (16.7%) 1:35 (2.8%) 8:35 (22.8%) 15:35 (42.8%)

0.04 pig/mI doxorubicin-resistant

specimens

1-h exposure 3:35 (8.6%) 4:35 (1 1 .4%) 12:35 (34.3%) 4:43 (9.3%) 1 1 :43 (25.6%) 23:43 (53.5%)

3.0 p.g/ml cyclophosphamide-

resistant specimens1-h exposure 0:21 (0.0%) 0:21 (0.0%) 4:21 (19.0%) 1:25 (4.0%) 6:25 (24.0%) 13:25 (52.0%)

a Specimens were tested along with conventional agents. Inhibition is given as the ratio of the number of specimens inhibited [colony formation

0.5 or less times that of the control:number of assessable specimens (%)].

(Fig. 1). To evaluate the relative effects of the duration of

exposure versus the concentration, we performed a scattergram

analysis that compares the relative cytotoxic effect of short

versus continuous exposures for each concentration of oxalipla-

tin (Fig. 2, Upper panel). As can be seen in Fig. 2, there was a

clear time-related cytotoxic effect with oxaliplatin, whereas no

time-related effects were observed with cisplatin and carbopla-

tin (Fig. 2, Lowerpanel). As shown in Tables 1 and 2, protracted

exposure induced higher cytotoxic effects in all of the tumor

types and in the specimens resistant to a variety of classical

anticancer drugs, respectively.

Effects in Tumors Resistant to Classical Cytotoxic

Agents. Cisplatin and carboplatin were tested along with ox-

aliplatin to detect tumors primarily resistant to cis-diammine-

platinum compounds. In cisplatin and carboplatin-resistant tu-

mors, the activity of oxaliplatin was concentration and time

dependent (Table 2). Head-to-head comparisons in tumor spec-

imens showed that a 1-h exposure to 50 and 10.0 pig/mI

oxaliplatin led to 7.4 and 23.4% in vitro responses, respectively;

in specimens resistant to 0.2 pig/mi cisplatin at 1-h exposure, the

same concentrations of oxaliplatin given as a 14-day exposure

schedule led to 31.5 and 51 .7% in vitro responses. Similarly,

head-to-head comparisons showed that a 1-h exposure to 5.0 and

10.0 pig/mi oxaliplatin led to 10.2 and 28.4% in vitro responses

in specimens resistant to 1.4 pig/mI carboplatin at 1-h exposure,

whereas these concentrations of oxaliplatin in the 14-day expo-

sure schedule led to 32.9 and 55.3% in vitro responses, respec-

tively. Oxaliplatin showed similar activity in tumors resistant to

protracted exposure to cisplatin and carboplatin (Table 2).

We subsequently compared the effects of oxaliplatin in

specimens resistant to 1-h exposure to 5-FU, irinotecan, pacli-

taxel, doxorubicin, and cyclophosphamide. We observed that a

1-h exposure to 5.0 and 10.0 pig/ml oxaliplatin showed in vitro

antitumor activity in 17.2 and 34.5% of specimens resistant to

6.0 pig/mI 5-FU, in 10.0 and 20.0% of specimens resistant to 3

pig/ml irinotecan, in 6.7 and 16.7% of specimens resistant to 10

pig/mI paclitaxel, in 1 1.4 and 34.3% of specimens resistant to

0.04 pig/mI doxorubicin, and in 0.0 and 19% of specimens

resistant to 3 pig/mI cyclophosphamide, respectively. The cyto-

toxic effects of oxaliplatin in drug-resistant specimens was

improved when oxaliplatin was given as a 14-day exposure

(Table 2).

Although cytotoxic activity of oxaliplatin was observed in

some but not all specimens that were resistant to classical

anticancer agents, this in vitro study was not designed to clearly

answer the cross-resistance between oxaliplatin and other anti-

cancer drugs. Therefore, observation of in vitro responses in

some specimens may lead to an overestimation of the antipro-

liferative effects of oxaliplatin as compared to other drugs.

Moreover, almost all drugs, if given at a sufficiently high

concentration, may have activity against specimens that are

resistant to classical anticancer agents. To compare the relative

antiproliferative effects of oxaliplatin with those of classical

anticancer drugs, we performed a scattergram analysis compar-

ing percentages of survival in specimens exposed to several

concentrations of oxaliplatin and cisplatin or carboplatin. This

approach was proposed as an alternative to the somewhat arbi-

trary and stringent definition of resistance (i.e., anything less

than a 50% colony killing). As can be see in Fig. 3, even at low,

0.5 pig/mi, concentrations, some tumor specimens were resistant

to cisplatin but not to oxaliplatin (Fig. 3A) and carboplatin (Fig.

3D). However, when given as a 1-h exposure, data showed that



B � �

,y:;.ft. � #{149}

E � �0 � I

� 0 �0 j� � � e

S

0

- �.�o-Cty/�.

0 7/01 #{149}%lo o o

.1’ #{149}to�o#{149} o�

0.5 jig/mI


100

E

:1.

C

0.0

.0

C-)

75

50

25

0 25 50 75 100 0

5.0 j.tg/mI

Oxaliplatin

25 50 75 160

10.0 jig/mI

Fig. 3 Scattergrams compar-

ing survival following expo-

sures to 0.5, 5.0, and 10.0 pig/ml

oxaliplatin with that of 0.2

pig/mi cisplatin and 1.4 pig/mI

carboplatin, respectively. Each

point represents data from oneindividual specimen. Points

were generated by calculating

the percentage survival in mdi-

vidual specimens exposed to ci-

ther oxaliplatin (X axis) andother compounds (Y axis), such

as cisplatin (A, B, and C) or

carboplatin (D, E, and F), re-

spectively. Activity of short-

term (#{149})versus long-term (0)

exposures to oxaliplatin along

with other drugs is also shown.

Graphs are presented with thebest-fitted linear regressions

that show a tendency for con-

centration-related (-) and

time-related (- - - -) cytotoxic

effects with oxaliplatin at 0.5,

5.0, and 10.0 pig/ml concentra-tions.

oxaliplatin has similar activity to cisplatin and carboplatin in the

overall population of specimens. Differences in terms of anti-

proliferative effects between oxaliplatin and other platinum

compounds appeared for concentrations above 5.0 pig/mI (Fig.

3, B, C, E, and F). Moreover, continuous exposures increased

the activity of oxaliplatin in both specimens sensitive and re-

sistant to cisplatin and oxaliplatin. A similar approach has been

performed for comparing the antiproliferative effects of several

concentrations of oxaliplatin with those of 5-FU, paclitaxel,

irinotecan, and doxorubicin (Fig. 4). In this study, we observed

that the overall antiproliferative activity of oxaliplatin was

higher than that of those compounds only for concentrations

above 5 pig/mI.

DISCUSSION

Our data show that oxaliplatin exerts potent in vitro cyto-

toxic activity against a large variety of human tumor colony-

forming units taken directly from patients. In this study, in vitro

responses were observed in non-small cell lung, breast, and

gastric cancers. Moreover, responses were also observed in

colon cancer, and despite a limited number of specimens, ac-

tivity was shown in melanoma, renal cell carcinoma, and sar-

coma, which are commonly considered highly resistant to con-

ventional anticancer drugs. Our results are fully consistent with

previous reports showing that oxaliplatin has antiproliferative

activity in vitro against human cancer cell lines (12) and in vivo

against several types of human tumor xenografts including

L1210 leukemia (29, 30), LGC lymphoma (31), MA-16c mam-

mary carcinoma (6, 31), M5076 sarcoma (30, 32), B16 mela-

noma (30, 32), C38 colon carcinoma (30, 32), P388 leukemia

(32), L4OAkR leukemia (31), and Lewis lung carcinoma (30,

32). Interestingly, the spectrum of activity of oxaliplatin in vitro

and in vivo seems to differ from that of cis-diammine-platinum

compounds. In a recent study using the National Cancer Insti-

tute’s anticancer drug screen database in a panel of 60 human

cancer cell lines, investigators have compared, using the Pear-

son correlation coefficient, the sensitivity profiles of dach-plat-

mum compounds, including oxaliplatin versus cis-diammine

compounds (12). They showed that dach-platinum compounds,

including oxaliplatin, belong to a family separated from cis-

diammine-platinum compounds that includes cisplatin and car-

boplatin. The authors suggested that oxaliplatin may have one or

more different cellular targets, mechanisms of action, and/or

mechanisms of resistance from those of cisplatin. In our study,

we showed that oxaliplatin has in vitro antiproliferative effects

against colon cancer cells that are usually considered resistant to

cisplatin. The specific activity of oxaliplatin in colon cancer is

the best-documented example of the different spectrum of ac-

tivity of oxaliplatin. More recent evidence suggests that the loss

of mismatch repair that occurs early in the acquisition of cis-

diammine-platinum resistance in colon cancer cells displays a

strong carrier ligand specificity for cis-diammine versus dach-

platinum adducts (16). The activity of oxaliplatin against cob-

rectal cancer has previously been well documented in clinical

trials showing overall response rates of 20 and 10% in patients

with previously untreated and 5-FU-resistant colorectal cancer,

respectively (23-25). Although modest, those results are clearly

superior to cisplatin and compared favorably with clinical re-

sults obtained with the best modulations of 5-FU and with

single-agent irinotecan in patients with advanced colon cancer



:�E,100 B #{149}

I �___________

I�

:�

M)� 75

I :

25 50 75 iOo

0.5 . 10.0 pigln�

Oxaliplatin


0 25 50 75 100

0.5 - 10.0 ptg1n�

Oxaliplatin

Fig. 4 Scattergrams comparing survival following exposures to 0.5(+), 5.0 (0), and 10.0 p.g/ml (S) oxa!iplatin with that of 6.0 p.g/ml5-fluorouracil (A), 2.5 pig/mI paclitaxe! (B), 1.5 pig/mI irinotecan (C),

and 0.04 pig/mI doxorubicin (D), respectively. Each point represents

data from one individual specimen. Points were generated by calculatingpercentage survival in individual specimens exposed to oxaliplatin (Xaxis) and other compounds (Y axis), such as 5-fluorouracil (A), pacli-taxe! (B), irinotecan (C), and doxorubicin (D), respectively. Activity of1-h exposure to 0.5 (+), 5.0 (0), and 10.0 pig/ml oxaliplatin (#{149})versus

a single concentration of each of the other drugs is also shown. Graphsare presented with the best-fitted linear regressions that show a tendencyfor concentration-related cytotoxic effects with oxaliplatin at concentra-tions ranging from 0.5 (- - - -), 5.0 (-), and 10.0 pig/mI (-).

(33). Because clinical experience with oxaliplatin remains mod-

est, our results showing in vitro responses in non-small cell

lung, ovarian, breast, and gastric cancers and melanomas en-

courage further clinical investigation with oxaliplatin in those

tumor types.

In our study, we showed that the duration of exposure is an

important parameter in oxaliplatin cytotoxicity in vitro. In this

study, a 2-fold increase in the in vitro response rate was obtained

by increasing the duration of exposure to oxaliplatin. This

finding may be important to consider in future studies investi-

gating the mechanism of action of oxaliplatin in cultured cancer

cells. However, this in vitro study does not pretend to provide

any schedule design for a clinical trial, and there is no clinical

information supporting the notion that concentrations of oxali-

platin above 5.0 pig/ml may be sustainable for 14 days in

patients. Although only one Phase I study showed that the

toxicity profile of oxaliplatin was not affected when given in

protracted infusion over 5 days (34), no pharmacokinetic data

investigating protracted-infusion oxaliplatin are currently avail-

able. Moreover, whether the favorable cytotoxic effects of pro-

longed exposures to oxaliplatin in vitro may be translated into

benefits in clinical trials is obviously questionable. Pharmaco-

kinetic data showed that oxaliplatin has a very large volume of

distribution after short-term iv. injection (7). Moreover, oxali-

platin accumulated progressively in RBCs with a long terminal

half-life close to that of erythrocytes ( 17). It is therefore possible

that oxaliplatin rapidly accumulates and remains in cells after a

single bolus injection. Further animal studies may be necessary

to determine whether sequestration of oxaliplatin can be main-

tamed in tumor xenografts after a single injection and whether a

protracted infusion can increase the antitumor activity of this

drug.

Our data showed that oxaliplatin has in vitro activity in

some tumors that were spontaneously resistant to cisplatin and

carboplatin. To date, there are several reports showing that

acquired resistance to cisplatin does not systematically confer

cross-resistance to dach-platinum compounds such as oxalipla-

tin in cisplatin-resistant cancer cell lines selected by prolonged

culture in the presence of the drug (12). However, there is little

information regarding the activity of oxaliplatin in human can-

cers primarily resistant to cis-diammine-platinum compounds

(35). In this study, we showed that concentrations between 5.0

and 10.0 pig/ml can induce in vitro response in tumors that were

primarily resistant to cisplatin and carboplatin. Moreover, we

showed that both concentration and duration of exposure are

important factors for oxaliplatin cytotoxicity against cisplatin-

and carboplatin-resistant cancers. Recent studies have suggested

that defects in mismatch repair can lead to cisplatin resistance

(16, 36). Supporting the importance of mismatch repair in

oxaliplatin cytotoxicity, it has been shown that colon carcinoma

cell lines, defective in either the hMLH1 or hMSH2 mismatch

repair enzymes, are 2-fold resistant to cisplatin but display little

or no resistance to oxaliplatin (16). Thus, the current data

suggest that loss of mismatch repair activity may be a frequent

occurrence in the acquisition ofcisplatin resistance (37, 38). The

difference in the mismatch repair of platinum DNA lesions

induced by cisplatin and oxaliplatin may also be consistent with

differences in the spectrum of activity between those two drugs

in colorectal and ovarian cancers cells.

This study also found that concentrations above 5 pig/mi

oxaliplatin have activity in some tumors that are primarily

resistant (or not sensitive) to conventional concentrations of

5-FU, irinotecan, paclitaxel, doxorubicin, and cyclophospha-

mide. This was observed using both a stringent definition of

resistance (less than 50% colony killing) and a more sophisti-

cated scattergram analysis comparing the antiproliferative ef-

fects of drugs. For example, 10.0 pig/ml oxaliplatin (1 h) in-

duced in vitro response in 34.5, 20.0, 16.7, 34.3, and 19.0% of

tumors primarily resistant to 5-FU, irinotecan, paclitaxel, doxo-

rubicin, and cyclophosphamide, respectively. These data are of

particular interest for clinical applications considering the im-

portance of 5-FU, irinotecan, and oxaliplatin in the treatment of

advanced colon cancer (24, 33). As indicated previously, Phase

II studies have shown that single-agent oxaliplatin has activity

in patients with colorectal cancers that acquired resistance to

5-FU (23). Little preclinical and clinical evidence is actually

available concerning the activity of oxaliplatin in cancer cells

expressing primary resistance to irinotecan, paclitaxel, doxoru-

bicin, or cyclophosphamide. Therefore, our results encourage

preclinical and clinical studies evaluating the antitumor effects

of oxaliplatin in tumors resistant to 5-FU, innotecan, paclitaxel,

or doxorubicin and suggest that the addition of oxaliplatin to

combination chemotherapy containing those classical anticancer

drugs may improve the antitumor effects.




30. Tashiro, T., Kawada, Y., Sakurai, Y., and Kidani, Y. Antitumor

activity of a new platinum complex oxalato (trans-l-l,2-diaminocyclo-

In summary, we showed that the duration of exposure is an

important parameter in oxaliplatin cytotoxicity in vitro. In ad-

dition, oxaliplatin shows potent in vitro cytotoxic activity

against a large variety of human tumors in the human tumor

cloning assay, including colon cancer, non-small cell lung can-

cer, breast cancer, and melanoma. Moreover, oxaliplatin dis-

played activity in some tumors that showed initial resistance to

cisplatin, carboplatin, 5-FU, and innotecan. Those results en-

courage further clinical investigation of oxaliplatin alone or in

combination with these drugs in patients with advanced cancers

refractory to conventional chemotherapy.

ACKNOWLEDGMENTS

We thank Peggy Durack and Meridith Sterling (Institute for Drug

Development, San Antonio, TX) for their excellent assistance in col-

lecting the data and preparing the manuscript for publication.

REFERENCES1. Chancy, S. The chemistry and biology of platinum complexes with

the 1,2-diaminocyclohexane carrier ligand (Review). Int. J. Oncol., 6:1291-1305, 1995.

2. Kidani, Y., Inagaki, K., and Tsugagoshi, S. Examination of antitumoractivities of platinum complexes of 1 ,2-diaminocyclohexane isomers.

Gann, 67: 921-922, 1976.

3. Kidani, Y., Inagaki, K., Ligo, M., Hoshi, A., and Kuretani, K.Antitumor activity of 1,2-diaminocyc!ohexane-platinum complexesagainst sarcoma-180 ascite form. J. Med. Chem., 21: 1315-1318, 1978.

4. Siddik, Z. H., al-Baker, S., Thai, G., and Khokhar, A. R. Antitumor

activity of isomeric 1,2-diaminocyclohexane platinum(IV) complexes.

J. Cancer Res. Clin. Oncol., 120: 409-414, 1994.

5. Skou, G., Mangold, G., Dexter, D., and Von Hoff, D. Comparison ofan oxaliplatin-Taxol versus a carboplatin-Taxol regimen in the treatmentof the MV-522 human lung tumor xenografts. Proc. Am. Assoc. Cancer

Res., 37: 375, 1996.

6. Raymond, E., Buquet-Fagot, Djellou!, C., J., Mester, E., Cvitkovic,C., Louvet, C., and Gespach, C. Antitumor activity of oxaliplatin incombination with 5-fluorouracil and the thymidase synthase inhibitor

AG337 in human colon, breast, and ovarian cancers. Anticancer Drugs,

8: 876-885, 1997.

7. Bastian, G. Report on the pharmacokinetic of oxaliplatin in patientswith normal and impaired renal function. Ann. Oncol., 5: 126, 1994.

8. Extra, J. M., Espie, M., Calvo, F., Ferme, C., Mignot, L., and Marty,

M. Phase I study of oxaliplatin in patients with advanced cancer. CancerChemother. Pharmacol., 25: 299-303, 1990.

9. Schmidt, W., and Chancy, S. G. Role of carrier ligand in platinumresistance of human carcinoma cell lines. Cancer Res., 53: 799-805,

1993.

10. Petersen, L. N., Mamenta, E. L., Stevnsner, T., Chancy, S. G., and

Bohr, V. A. Increased gene specific repair of cisplatin induced inter-

strand cross!inks in cisplatin resistant cell lines, and studies on carrierligand specificity. Carcinogenesis (Lond.), 17: 2597-2602, 1996.

11. Mamenta, E. L., Poma, E. E., Kaufmann, W. K., Delmastro, D. A.,

Grady, H. L., and Chancy, S. G. Enhanced replicative bypass of plati-num-DNA adducts in cisplatin-resistant human ovarian carcinoma cell

lines. Cancer Res., 54: 3500-3505, 1994.

12. Rixe, 0., Ortuzar, W., Alvarez, M., Parker, R., Reed, E., Paull, K.,

and Fojo, T. Oxaliplatin, tetraplatin, cisplatin, and carboplatin: spectrum

of activity in drug-resistant cell lines and in the cell lines of the NationalCancer Institute’s Anticancer Drug Screen panel. Biochem. Pharmacol.,52: 1855-1865, 1996.

13. Page, J. D., Husain, I., Sancar, A., and Chancy, S. G. Effects of thediaminocyclohexane carrier ligand on platinum adduct formation, re-

pair, and lethality. Biochemistry, 29: 1016-1024, 1990.

14. Bruk, M. A., Bau, R., Noji, M., Inagaki, K., and Kidani, Y. The

crystal structure and absolute configurations of the antitumor complexes

Pt(oxalato)(lR,2R-cyclohexanediamine) and Pt(malanato)(1R,2R-cyclo-hexanediamine). Inorg. Chem. Acta, 92: 279-284, 1984.

15. Lock, C. J. L., and Pilon, P. Tris-[cis-dichloro(1,2-diamino-

cyclohexane)p!atinum(II)] hydrate and cis-dibromo(l,2-diaminocyclo-

hexane)p!atinum(II). Acta Ciystallogr. Sect. B Struct. Sci., B27: 45-49,

1981.

16. Fink, D., Nebel, S., Aebi, S., Zheng, H., Cenni, B., Nehme, A.,

Christen, R. D., and Howell, S. B. The role of DNA mismatch repair in

platinum drug resistance. Cancer Res., 56: 4881-4886, 1996.

17. Gamelin, E., Le Bouil, A., Boisdron-Celle, M., Turcant, A.,Delva, R., Cailleux, A., Krikorian, A., Brienza, S., Cvitkovic, E.,Robert, J., Larra, F., and Allan, P. Cumulative pharmacokineticstudy of oxaliplatin, administered every three weeks, combined with

5-fluorouraci! in colorectal cancer patients. Clin. Cancer Res., 3:

891-899, 1997.

18. Pendyala, L., and Creaven, P. J. In vitro cytotoxicity, proteinbinding, red blood cell partitioning, and biotransformation of oxalipla-

tin. Cancer Res., 53: 5970-5976, 1993.

19. Pendyala, L., Kidani, Y., Perez, R., Wilkes, J., Bernacki, R. J., and

Creaven, P. J. Cytotoxicity, cellular accumulation and DNA binding of

oxaliplatin isomers. Cancer Lett., 97: 177-184, 1995.

20. Bleiberg, H. Role of chemotherapy for advanced colorectal cancer:

new opportunities. Semin. Oncol., 23: 42-50, 1996.

21. de Gramont, A., Vignoud, J., Tournigand, C., Louvet, C., Andre, T.,

Varette, C., Raymond, E., Moreau, S., Le Bail, N., and Krulik, M.Oxaliplatin with high-dose leucovorin and 5-fluorouracil 48-hour con-tinuous infusion in pretreated metastatic colorectal cancer. Eur. J. Can-cer, 33: 214-219, 1997.

22. Levi, F., Perpoint, B., Garufi, C., Focan, C., Chollet, P., Depres-Brummer, P., Zidani, R., Brienza, S., Itzhaki, M., lacobelli, S., et al.

Oxaliplatin activity against metastatic colorectal cancer: a Phase II studyof 5-day continuous venous infusion at circadian rhythm modulated rate.

Eur. J. Cancer, 9: 1280-1284, 1993.

23. Becouarn, Y., Ychou, M., Ducreux, M., Bore!, C., Bertheault-Cvitkovic, F., Seitz, J. F., Nasca, S., Rougier, P., Nguyen, T. D., Pailbot,

B., Raoul, J. L., and Fandi, A. Oxaliplatin (l-OHP) as first line chem-otherapy in metastatic colorectal cancer (MCRC) patients: preliminary

activity/toxicity report. Proc. Am. Soc. Clin. Oncol. Annu. Meet., 16:

229, 1997.

24. Machover, D., Diaz-Rubio, E., de Gramont, A., Schilf, A., Gastia-buru, J. J., Brienza, S., Itzhaki, M., Metzger, G., N’Daw, D., Vig-noud, J., Abad, A., Francois, E., Gamelin, E., Marty, M., Sastre, J.,Seitz, J. F., and Ychou, M. Two consecutive Phase II studies of oxali-

platin (L-OHP) for treatment of patients with advanced colorectal car-

cinoma who were resistant to previous treatment with fluoropyrimi-

dines. Ann. Oncol., 7: 95-98, 1996.

25. Bleiberg, H., Gamelin, E., Francois, E., Andre, T., Extra, J. M.,Nole, F., Bensmaine, M. A., Itzhaki, M., Brienza, S., and Cvitkovic, E.

Oxaliplatin (l-OHP) synergistic clinical activity with 5-fluorouracil (FU)

in FU-resistant colorectal cancer (CRC) patients (pts) is independent of

Hi +/- folinic acid (FA). Proc. Am. Soc. Clin. Oncol. Annu. Meet.,

16: 206, 1996.

26. Von Hoff, D., Sandbach, J., Clark, G., Turner, J., Forseth, B.,

Piccart, M., Colombo, N., and Muggia, F. Selection of cancer chemo-

therapy for patient by an in vitro assay versus a clinician. J. Nat!. CancerInst., 82: 110-116, 1990.

27. Von Hoff, D., Clark, G., Stogdill, B., Sarosdy, M., O’Brien, M.,Casper, T., Mattox, D., Page, C., Cruz, A., and Sandbach, J. Prospectiveclinical trial of human tumor cloning system. Cancer Res., 43: 1926-

1931, 1983.

28. Von Hoff, D. Human tumor stem cell assay. Curr. Ther. Hematol.

Oncol., 3: 365-367, 1987.

29. Mathe, G., Kidani, Y., Noji, M., Maral, R., Bourut, C., and Chenu,

E. Antitumor activity of 1-01W in mice. Cancer Lett., 27: 135-143,

1985.




hexane)p!atinum(ll): new experimental data. Biomed. Pharmacother.,43: 251-260, 1989.

31. Mathe, 0., Kidani, Y., Segiguchi, M., Edguchi, M, Fredj, G.,Peytavin, 0., Misset, J. L., Brienza, S.. de Vassal, F., and Chenu, E.Oxalato-platinum or l-OHP, a third-generation platinum complex: anexperimental and clinical appraisal and preliminary comparison withcis-p!atinum and carboplatinum. Biomed. Pharmacother., 43: 237-250,

1989.

32. Kidani, Y., Inagaki, K., Saito, R., and Tsukagshi, S. Synthesis andanti-tumor activities of platinum (II) complexes of 1,2-diaminocycbo-

hexane isomers and their related activities. J. Clin. Haematol. Oncol., 7:197-209, 1977.

33. Bleiberg, H. Role of chemotherapy for advanced colorectal cancer:new opportunities. Semin. Oncol., 23: 42-50, 1996.

34. Caussanel, J. P., Levi, F., Brienza, S., Misset, J. L., Itzhaki, M.,Adam, R., Milano, 0., Hecquet, B., and Mathe, 0. Phase I trial of 5-daycontinuous venous infusion of oxaliplatin at circadian rhythm-modu-

lated rate compared with constant rate. J. Nail. Cancer Inst., 82: 1046-1050, 1990.

35. Pendyala, L., Creaven, P. J., Perez, R., Zdanowicz, J. R., andRaghavan, D. Intracellular glutathione and cytotoxicity of platinumcomplexes. Cancer Chemother. Pharmacol., 36: 271-278, 1995.

36. Aebi, S., Kurdihaidar, B., Gordon, R., Cenm, B., Zheng, H., Fink,D., Christen, R. D., Boland, C. R., Koi, M., and Fishel, R. Loss of DNAmismatch repair in acquired resistance to cisplatin. Cancer Res., 5:

3087-3090, 1996.

37. Mello, J. A., Acharya, S., Fishel, R., and Essigann, J. M. Themismatch-repair protein hMSH2 binds selectively to DNA adducts ofthe anticancer drug cisplatin. Chem. Biol., 3: 579-589, 1996.

38. Duckett, D. R., Drummond, J. T., Murchie, A. I. H., Reardon, J. T.,

Sancar, A., Lilley, D. M. J., and Modrich, P. MutSa recognizes damagedDNA base pairs containing 06-methylguanine, O”-methylthymine or thecisplatin-d(GpG) adduct. Proc. Natl. Acad. Sci. USA, 93: 6443-6447,1996.



1998;4:1021-1029. Clin Cancer Res E Raymond, R Lawrence, E Izbicka, et al. units.Activity of oxaliplatin against human tumor colony-forming

Updated version

http://clincancerres.aacrjournals.org/content/4/4/1021

Access the most recent version of this article at:

E-mail alerts related to this article or journal.Sign up to receive free email-alerts

Subscriptions

Reprints and

[email protected] at

To order reprints of this article or to subscribe to the journal, contact the AACR Publications

Permissions

Rightslink site. Click on "Request Permissions" which will take you to the Copyright Clearance Center's (CCC)

.http://clincancerres.aacrjournals.org/content/4/4/1021To request permission to re-use all or part of this article, use this link



http://clincancerres.aacrjournals.org/cgi/alerts

mailto:[email protected]



Activity of Oxaliplatin against Human Tumor Colony-forming ... · Colony-forming Units1 Eric...

Documents

Transcript of Activity of Oxaliplatin against Human Tumor Colony-forming ... · Colony-forming Units1 Eric...