Oxaliplatin: A review of preclinical and clinical studies

Annals of Oncology 9: 1053-1071, 1998. © 1998 Kluwer Academic Publishers. Printed in the Netherlands.

Review Oxaliplatin: A review of preclinical and clinical studies E. Raymond,1 S. G. Chaney,2 A. Taamma3 & E. Cvitkovic3'4 ^Department of Medicine, Institut Gustave Roussy, Vtllejuif Cedex, France; 2 Department of Biochemistry & Biophysic, Mary Ellen Jones Building, University of North Carolinaat Chapel Hill, Chapel Hill, NC, USA; iC&AC, Kremlin Bicetre Cedex; 4Federation des Services des Maladies Sanguines Immunitaires et Tumorales — Hopital Paul Brousse, Villejuif France

Summary

Of the new generation platinum compounds that have been evaluated, those with the 1,2-diaminocyclohexane carrier ligand - including oxaliplatin - have been focused upon in recent years. Molecular biology studies and the National Cancer Institute in vitro cytotoxic screening showed that diaminocyclohexane platinums such as oxaliplatin belong to a distinct cytotoxic family, differing from cisplatin and carboplatin, with specific intracellular target(s), mechanism(s) of action and/or mechanism^) of resistance. In phase I trials, the dose-limiting toxicity of oxaliplatin was characterized by transient acute dysesthesias and cumulative distal neurotoxicity, which was reversible within a few months after treatment discontinuation. Moreover, oxaliplatin did not display any, auditory, renal and hematologic doselimiting toxicity at the recommended dose of 130 mg/m2 q three weeks or 85 mg/m2 q two weeks given as a two-hour i.v. infusion. Clinical phase II experiences on the antitumoral activity of oxaliplatin have been conducted in hundreds of patients with advanced colorectal cancers (ACRC). Single agent activity reported as objective response rate in ACRC patients is 10% and 20% overall in ACRC patients with 5-fluorouracil (5-FU) pretreated/refractory and previously untreated ACRC, respectively. Synergistic cytotoxic effects in preclinical studies with thymidylate synthase inhibitors, cisplatin/carboplatin and topoisomerase I inhibitors, and the absence of hematologic doselimiting toxicity have made oxaliplatin an attractive compound for combinations. Phase II trials combining oxaliplatin with 5-FU and folinic acid ACRC patients previously treated/refractory to 5-FU showed overall response rates ranging from

Introduction While a large number of second and third generation platinum (Pt) compounds were synthesized, those with the 1,2-diaminocyclohexane (DACH) carrier ligand have received the most attention in recent years. The synthesis of DACH-Pt complexes (Figure 1) was reported in the early 1970s, showing that DACH carrier ligand compounds were more effective than several other carrier-]igand Pt complexes against cisplatin-resistant mouse L1210 and P-388 leukemia cells [1-5]. Subsequent studies have shown that DACH-Pt compounds are ef-

21% to 58%, and survivals ranging from 12 to 17 months. In patients with previously untreated ACRC, combinations of oxaliplatin with 5-FU and folinic acid showed response rates ranging from 34% to 67% and median survivals ranging from 15 to 19 months. Two randomized trials totaling 620 previously untreated patients with ACRC, comparing 5-FU and folinic acid to the same regimen with oxaliplatin, have shown a 34% overall response rate in the oxaliplatin group versus 12% in the 5-FU/folinic acid group for the first trial; and 51.2% vs. 22.6% in the second one. These statistically significant differences were confirmed in time to progression advantage for the oxaliplatin arm (8.7 vs. 6.1 months, and 8.7 vs. 6.1 months, respectively). A small but consistent number of histological complete responses have been reported in patients with advanced colorectal cancer treated with the combination of oxaliplatin with 5-FU/folinic acid, and secondary metastasectomy is increasingly done by oncologists familiar with the combination. Based on preclinical and clinical reports showing additive or synergistic effects between oxaliplatin and several anticancer drugs including cisplatin, irinotecan, topotecan, and paclitaxel, clinical trials of combinations with other compounds have been performed or are still ongoing in tumor types in which oxaliplatin alone showed antitumoral activity such as ovarian, non-small-cell lung, breast cancer and non-Hodgkin lymphoma. Its single agent and combination therapy data in ovarian cancer confirm its non-cross resistance with cisplatin/carboplatin. While the role of oxaliplatin in medical oncology is yet to be fully defined, it appears to be an important new anticancer agent. Key words: colorectal cancer, diaminocyclohexane, ovarian cancer, oxaliplatin, platinum

fective against a variety of cisplatin-resistant human cancer cell lines and xenografts [6-21]. Kidani et al. [22-25] were the first to suggest that the stereochemical conformations of the DACH carrier ligand might affect the interactions of DACH-Pt compounds with DNA. DACH carrier ligands exist in three conformations: transL(R,R), trans-d(S,S) and cis(R,S). In cytotoxicity assays the trans-R,R isomers appear to be more effective than the trans-S,S isomers, and the cis-R,S isomers [6, 7, 16, 19-30] possibly through the differential recognition of the adducts by damage recognition proteins and/or damage processing complexes [31].

1054 Amongst the DACH-Pt compounds, oxaliplatin [trans-L-dach (1R, 2R-diaminocyclohexane) oxalatoplatinum, L-OHP] might prove to fulfill the original vision of a novel Pt complex with clinical efficacy against cisplatin- and carboplatin-resistant tumors. However, oxaliplatin remained relatively ignored for more than ten years. Amongst the reasons for this long development period was a very unique toxicity profile, mainly characterized by an acute sensitive, dose-dependent, and coldrelated peripheral neuropathy, whose benign and reversible clinical characteristics were only slowly recognized as such by investigators. Moreover, the exclusively French, and mainly oligocentric clinical development of oxaliplatin, focused on the treatment of advanced colorectal cancer patients was initially closely linked to chronomodulated continuous infusion administration. This led to confusion in the discrimination between the respective antitumoral effects of oxaliplatin and chronomodulation. Meanwhile, preclinical and clinical data confirmed significant differences both in the spectrum of activity and in the specific consequences of the Pt DNA interactions of oxaliplatin as compared to cisplatin or carboplatin. We will review published data on the cytotoxicity profile, mechanism of action, toxicity, and clinical activity of oxaliplatin, with a few references to as yet unpublished data.

A: Diamminocyclohexane Platinum Complexes ,0

a

NH

I Cl

Tetraplatin (Ormaplatin)

Oxaliplatin (I-OHP)

>rcl

0 — C'

w

*o

Malonatoplatin (Pl(mal)(dach))

PtC12(dach)

B: Cis-Diammine Platinum Complexes ,0

-CI

o—c "Pt

•Cl

NH3'

NH,

Carboplatin

Cisplatin

Figure 1. Structures of common platinum complexes with the 1,2diaminocyclohexane (panel A) and cis-diammine (panel B) carrier ligands.

hour) in red blood cells, up to 37% of the total platinum. This partitioning of platinum into red blood cells appears to be unique to oxaliplatin, since it has not been Biotransformation of oxaliplatin seen previously with either cisplatin or carboplatin [36], and has been recently confirmed in cumulative pharThe data obtained with the closely related compound macokinetic data on patients treated with multiple 1,2-diaminocyclohexanemalonato Pt(II) (malonatopla- courses [37]. tin) provide a useful model for understanding the bioAllen et al. have recently reported on biotransformatransformations of oxaliplatin [32]. The biotransforma- tion products isolated from plasma ultrafiltrate at the tion pathways for malonatoplatin and oxaliplatin are end of a 130 mg/m2 i.v. infusion oxaliplatin [38]. The summarized in Figure 2. The reactions of platinum data obtained in 10 patients confirm previous in vitro compounds with strong nucleophiles usually result in and animal results showing monochloro, dichloro, methe formation of inactive platinum complexes and can thonine, and glutathione DACH-Pt complexes in plasgenerally be considered as inactivation pathways. Con- ma and urine. versely, the reaction of platinum complexes with weaker nucleophiles, including the N(7) of guanines in the Mechanism of action DNA, requires prior aquation [33, 34], which is achieved after interaction with both HCO 3 - and H 2 PO 4 - at phys- Similarly to cisplatin, the main mechanism of action of iological concentrations. Thus, reactions with HCO 3 - in oxaliplatin is mediated through the formation of DNAtissue culture medium and plasma, and with intracellular adducts [39-41]. When the platinum compound enters HCO 3 - and H 2 PO 4 - are likely to represent major acti- the cell, one chloride ligand dissociates to form a reacvation pathways for malonatoplatin and oxaliplatin [32]. tive monoaquamonochloro complex, which reacts rapLuo et al. [35] have recently reported on the biotrans- idly with the N(7) of guanines on the DNA to form formations of oxaliplatin in rat blood in vitro. They monoadducts. The subsequent dissociation of the second found that the tl/2 of oxaliplatin was 41 min, 35 min chloro ligand allows the conversion of the transiently and 47 min in whole blood, red blood cells, and plasma, formed monoadducts to a variety of stable diadducts respectively. At equilibrium, approximately half of the [34, 42]. The majority are intrastrand diadducts binding oxaliplatin was bound to the red blood cells, 35% to a guanine residue [43, 44]. Since intrastrand adducts are plasma proteins and 12% was ultrafiltrable. Pendyala the most abundant adducts and are capable of blocking and Creaven [36] have reported on the biotransfor- both DNA replication and transcription, they are conmations of oxaliplatin in human blood in vitro. They sidered the major cytotoxic lesions. The other types of reported that platinum accumulates rapidly (Ti/2 < one adducts are represented by interstrand crosslinks, and Preclinical studies

1055 A: Diamminocyclohexane Platinum Complexes

a

NH

JN

NH/

a y

N

ci

H,O

a"

^ = ^ [Pt(H2O)(CI)(dach)]+

PtCI2(dach) Maloru(Dpla(!n

[Pt(H2O)2(dach)]2*

B: Cis-Diammine Platinum Complexes

N

V " C X>

NH^

N

0

H,O

cr

C,

carboplatin

NH,

NH,

cisplatin

[Pt{H 2 O)(Clj(NH 3 ) 2 ]*

NH,

OH 2

NH3

OH,

[Pt{H 2 O) 2 (NH 3 ) 2 ] 2 * Figure 2 Biotransformation pathways for oxaliplatin and other platinum complexes with dicarboxylate leaving ligands.

DNA-protein crosslinks [45, 46] appear to represent minor species (less than 1% of total platinum adducts). Although the formation of oxaliplatin-adducts is slower than cisplatin-adducts in vitro, oxaliplatin and other trans-DACH-platinum complexes form a type which is similar to cisplatin, and form interstrand adducts at similar sites than cisplatin in DNA [46-49]. However, in spite of the many similarities between oxaliplatin and cisplatin, there are some important differences in their target(s) and action mechanism(s) that may be related to their different activity profiles. First, DACH-platinum adducts are bulkier and more hydrophobic than cis-diammine-Pt adducts. Perhaps as a result, DACH-Pt adducts are more effective at inhibiting DNA synthesis [46, 50] and are generally more cytotoxic [15, 46, 51, 52] than cisplatin-adducts. In addition, monoadduct to diadduct conversion is slower for DACH-

platinum adducts [48], presumably because the N-PT-N bond angle is more constrained for DACH-Pt-DNA adducts than for cis-diammine-Pt-DNA adducts [53-55]. Finally, the mismatch repair (MMR) protein complex may be prevented from binding to oxaliplatin-adducts because of particular conformational distortions in the region of the adduct [56]. As a final result, oxaliplatin induces primary and secondary DNA lesions that lead to apoptosis in human cancer cells [57]. Preclinical activity In vitro studies Using the COMPARE computer program of the National Cancer Institute (NCI) aiming to identify families

1056 of cytotoxic agents based on the Pearson correlation coefficient of their sensitivity profiles in the Anticancer Drug Screen database [58], Rixe et al. [15] analyzed the sensitivity profiles of oxaliplatin, ormaplatin (tetraplatin) (two DACH-Pt compounds) with cisplatin and carboplatin. Their data show that all DACH-Pt compounds such as oxaliplatin and ormaplatin may be identified as a separate family, differing from cisplatin and carboplatin. The recent work on neural network analysis on the same NCI data base has confirmed the DACH-Pt compounds as a separate and original family of anticancer drugs [58], likely to differ from cisplatin and carboplatin in cellular target(s), mechanism(s) of action and/ or mechanism(s) of resistance, and thus potentially effective in tumors with intrinsic or acquired resistance to cisplatin or carboplatin. Oxaliplatin has shown potent antiproliferative activity (as good as, or better than, cisplatin) against mouse and human leukemia, colon, ovarian, breast, melanoma, bladder, glioma, and erythroleukemia cell lines [15, 36, 59]. Interestingly, the cytotoxic effects of oxaliplatin were maintained in human HT29 colon cancer cell lines and in a derived counterpart selected for resistance to 5-FU. Similarly, the antiproliferative effect of oxaliplatin in MCF7 breast cancer cells was not significantly affected by acquired resistance to doxorubicin [60]. Oxaliplatin has also shown little or no cross-resistance with cisplatin-resistant human ovarian, cervix squamous cell carcinoma [15], non-small-cell lung cancer [17], germ cell cancer [61] and mouse leukemia cell lines [62]. However, the non-cross resistance between oxaliplatin and cisplatin is not absolute, as DACH-Pt complexes are not effective in all cisplatin-resistant cell lines [13, 14]. In combination studies, supra-additive effects between oxaliplatin and 5-FU were observed in breast (MDA-MB-231), colon (HT29, HT29-5-FU-resistant and CaCo2), as well as in parental and cisplatin-resistant A2780 and 2008 ovarian cancer cells. Additive or supra-additive effects were observed when oxaliplatin was combined with recent specific thymidylate synthase inhibitors (such as AG337) [60]. Finally, cisplatin and oxaliplatin appear to be at least additive, and possibly synergistic, in the human KB and A2780 cell lines [15].

xenografts and hormone-independent GR1 mammary tumor models), cyclophosphamide (LI 210 mouse leukemia), carboplatin or cisplatin (LI 210 leukemia) [60, 66-68]. Finally, in the MV-522 human lung carcinoma xenografts, where paclitaxel was the only active single agent, oxaliplatin improved the activity of paclitaxel to a moderate extent and the combination of paclitaxel, oxaliplatin plus tirapazamine was highly synergistic [69]. Human tumor cloning assay A recent study was conducted to identify tumor types warranting phase II clinical trials of oxaliplatin using the human tumor cloning assay [70]. Oxaliplatin was tested at concentrations ranging from 0.5 to 50.0 ug/ml in one-hour and 14-day continuous exposures against 1.4 |ig/ml carboplatin and 0.2 ug/ml cisplatin for comparison. The in vitro response was defined as tumor growth inhibition > 50% of control. In the one-hour exposure schedule, in vitro responses were observed in nine of 116 (8%) 18 of 115 (16%), 38 of 103 (37%), and seven of 13 (54%) at concentrations of 0.5, 5.0,10.0, and 50.0 ug/ml oxaliplatin, respectively. Activity was observed against colon, non-small-cell lung, gastric cancer, and melanoma colony-forming units. In both cisplatinresistant and cisplatin-sensitive tumors, the activity of oxaliplatin was concentration and time dependent. A one-hour exposure to 10.0 ug/ml oxaliplatin led to 23.4% in vitro responses in specimens resistant to one-hour exposure of 0.2 ug/ml cisplatin. Moreover, a one-hour exposure to 10.0 ug/ml oxaliplatin showed in vitro antitumoral responses in 24.3%, 34.5%, 20.0%, 16.7%, and 34.3% of specimens resistant to 1.4 ug/ml carboplatin, 6.0 ug/ml 5-FU, 3.0 ug/ml irinotecan, 10.0 ug/ml paclitaxel, and 0.04 ug/ml doxorubicin, respectively. Mechanisms of resistance

DACH-Pt complexes are effective in some, but not all, cisplatin-resistant cell lines. It is thus important to determine which resistance mechanisms affect Pt compounds with the cis-diammine carrier ligand (cisplatin and carboplatin), but not Pt compounds with the DACH carrier ligand. In vivo models Decreased accumulation and/or increased efflux is In mouse tumor models, oxaliplatin has proven to be one of the most frequent mechanisms of cisplatin resistmore effective than cisplatin against L1210 leukemia ance [8] and may be one of the earliest resistance [62-64], LGC lymphoma [65], MA-16c mammary carci- mechanisms to develop for cell lines exposed to cisplatin noma [65], and M5076 sarcoma [62, 63]. Oxaliplatin is repeatedly [71, 72]. Increases in metallothionein, glutaat least as effective as cisplatin against B16 melanoma thione and/or glutathione S-transferase [8] have been [62-64], C38 colon carcinoma [62-64], P388 leukemia reported in many cisplatin-resistant cell lines. Presum[63, 64], L40AkR leukemia [65], and Lewis lung carci- ably the increased intracellular levels of metallothionein noma [62-64]. It has also proven effective against several and/or glutathione could lead to inactivation of Pt mouse tumors with acquired or intrinsic resistance to complexes before they had a chance to react with DNA, cisplatin [62, 63, 65]. For oxaliplatin-based combina- to quenching of Pt-DNA monoadducts before conversion tions, the results observed in vitro translate in an increase to more lethal diadducts, or efflux of the Pt-glutathione of antitumoral activity in mice. For example, oxaliplatin conjugates. However, based on chemical reactivity there increased the antitumoral activity of 5-FU (HT29 colon is no reason to expect any differences in the reactions of

1057 Table 1. Oxaliplatin phase I trials. Total no. of patients

Short infusion Mathe [88]a Extra [89] Armandb Taguchib Chevalierb Continuous infusion11 Caussanel [90] CMI CI

Schedule

23 44 7 20 3

Bolus q 3 w 1-12 h q 3-4 w 1-2 h q 3 w l-2hq3-4w 2 hq 3 w

12 13

q3w q3w

No. of patients/dose level (mg/m2)

MTD (mg/m2)

RD (mg/m2)

DLT

=£90

130-135

150-180

200

23 8 _ 9 -

12 6 -

19 5 3

5 7 _ -

NR 200 180 -

>67 135 130 175

NR Neurotoxicity Neurotoxicity -

-

13 12

4 6

0 4

200 175

125 150

Neurotoxicity Neurotoxicity

Abbreviations: MTD - maximal tolerated dose; DLT - dose-limiting toxicity; RD - phase II recommended dose; NR - not reached; CMI chronomodulated continuous infusion; CI - flat continuous infusion. a Intra-patient dose escalation. b Personal communication.

cis-diammine-Pt and DACH-Pt complexes with sulfurcontaining nucleophiles [73, 74]. Increased nucleotide excision repair activity is also an important mechanism of Pt resistance. However, both prokaryotic and eukaryotic nucleotide excision repair complexes have very broad specificity [75]. In terms of cellular DNA repair, there also appears to be little or no specificity for the repair of Pt-DNA adducts with cis-diammine, ethylenediamine(en), or DACH carrier ligands. Post-replication repair is best defined as the ability to replicate past bulky DNA adducts without introducing gaps or discontinuities into the DNA [76-80]. As defined, post-replication repair is not a 'true repair' process, since the damaging adduct is not actually removed from the DNA. For this reason, it is often referred to as a replicative bypass of the adducts. This replicative bypass is enhanced in several cisplatin-resistant cell lines, but not in the replicative bypass of oxaliplatin-adducts [81]. In these models, the relative ability to replicate past adducts correlated with the carrier ligand specificity, and the bulky DACH-Pt adducts were more effective at blocking DNA chain elongation in all of the human carcinoma cell lines studied to date [50]. Recent experiments have suggested that defects in mismatch repair can also lead to cisplatin resistance which occurs frequently during the acquisition of cisplatin resistance in cell culture and has been incriminated in resistance occuring after repeated cycles of cisplatin in clinical trials [82]. In understanding how defects in mismatch repair can lead to resistance, it is important to note that this system removes the mismatch on the newly synthesized strand of DNA. The defect in mismatch repair allows resistant cells to tolerate DNA damage and replicate, instead of undergoing cell-cycle arrest or cell death. Recently, Fink et al. [82, 83] have shown that colon carcinoma cell lines either defective in the hMLHl or hMSH2 mismatch repair enzymes are 1.5 to two-fold resistant to cisplatin, but display little or no resistance to oxaliplatin [83]. Moreover, several laboratories have

shown that the mismatch repair complexes recognize cisplatin diadducts [82,84,85], but not DACH-Pt diadducts in DNA. The induction of mismatch repair defects has been shown to correlate with acquired resistance to cisplatin while the sensitivity to oxaliplatin was maintained and have suggested that defective mismatch repair activity displayed strong carrier ligand specificity for cis-diammine-Pt versus DACH-Pt adducts [86]. Defects in hMSH2 and hMSH6 but not hMSH3 [87] seem to be specifically linked to the differential cytotoxicity between oxaliplatin and cisplatin. Based on those results, it has been suggested that this particular mechanism of resistance may account in the differential cytotoxicity profile between DACH- and cis-diammine-Pt compounds in vivo.

Toxicity and pharmacokinetics Short-infusion phase I trials Starting in 1984, five phase I studies were conducted with short infusion oxaliplatin given every three to four weeks (Table 1). The first phase I study, which included twenty three patients, was initiated by Mathe et al. [88] using intra-patient dose escalation. Based on the toxicity profile in mice, the starting dose was 0.45 mg/m2 and the dose was escalated through nine dose levels up to 67 mg/m2. The maximum tolerated dose (MTD) was not reached in this study. However, they observed that the toxicity profile of oxaliplatin was different from that of cisplatin, including no nephrotoxicity, and only mild nausea and vomiting. Interestingly, despite the utilization of low doses, one complete and one partial response were observed. The second phase I study was conducted by Extra et al. [89]. Forty four patients were treated with one-hour infusion oxaliplatin at doses ranging from 30 to 200 mg/m2 at infusion times from 30' to 120'. More recently, another phase I study was performed in Japan by Tagu-

1058 Table 2. Dose-related toxicity of oxaliplatin as a two-hour infusion in phase I trials. Doses (mg/m2) 130-135

150-180

200 (%)

(%)0 Number of patients Toxicity Neutropenia Grade 1-2 Grade 3-4 Thrombocytopenia Grade 1-2 Grade 3-4 Anemia Grade 1-2 Grade 3^1 Nausea/vomiting Grade 1-2 Grade 3-4 Acute neurotoxicity Grade 1-2 Grade 3^1 Diarrhea Grade 1-2 Grade 3-4

40 pts

Table 3. Neurological toxicity specific grading.a Grade 1 Grade 2 Grade 3 Grade 4 a

18 pts

27 pts

Paresthesia/dysesthesia Paresthesia/dysesthesia Paresthesia/dysesthesia Paresthesia/dysesthesia

of short duration < 7 days lasting eight to 14 days persisting in the intercycle period causing functional impairment

From Caussanel et al. [90],

12 pts

lasted for a few minutes to a few days, and were fully reversible. The intensity was generally mild to moderate 0 0 0 0 (Table 2). This toxicity was almost always present from the dose of 90 mg/m2 and increased with dose, up to 0 4(20) 9(33) 6(50) 75% of patients treated at 200 mg/m2. The duration and 0 1(4) 0 0 intensity of the symptoms increased with the number of courses. Interestingly, these symptoms disappeared within 1(8) 4(15) 1 (2-5) 1(5) six months following the end of treatment in most of the 0 0 0 0 patients. This study suggested cumulative neurotoxicity, 26 (65) 5(27) 10 (37) 4(34) which was confirmed by subsequent phase II trials. High 7(17) 13(70) 13(48) 8(83) doses (>175 mg/m2) of oxaliplatin were subsequently evaluated by Chevalier (personal communication) and 4(10) 10(55) 14(52) 9(75) Armand (personal communication) in a total of 10 1 (2.5) 3(16) 9(33) 3(25) patients in two phase I—II experiences. Some patients 1 (2.5) 4(22) 6(22) 1(8) receiving oxaliplatin at the dose of 175 mg/m2 developed 0 0 3(11) 4(33) a mild iaryngeal spasm' during infusion. This symptom disappeared without any specific medication and did not require treatment discontinuation. At such high chi et al. (personal communication) in which twenty doses, oxaliplatin was shown to induce severe nausea patients were treated at doses ranging from 20 to 180 and vomiting in 33% and severe neurotoxicity in 20% of mg/m2 given over two hours i.v. Since no renal toxicity patients. From these studies it was also concluded that was observed in the first phase I study, subsequent trials even such high doses of oxaliplatin did not induce hemawere conducted without hydration. In both studies, there tological dose-limiting toxicity. Objective responses were was no hematological dose-limiting toxicity (DLT). Hem- observed in all phase I studies in a variety of malignanatological toxicity was often mild to moderate, character- cies, including bladder, head and neck, breast and coloized by grade 1 or 2 neutropenia and thrombocytopenia rectal cancer. (Table 2). Neurotoxicity was considered the dose limiting toxNausea and vomiting were frequently reported. How- icity of oxaliplatin. Since the WHO toxicity grading ever, no systematic antiemetic prophylaxis was employed system does not consider the duration of the neuroprior to oxaliplatin administration in phase I trials. sensory component in the neurological symptoms, and Therefore 70% to 83% of patients experienced grade the neurosensory component is not particularly focused 3-4 nausea and vomiting for doses ranging from 130 to on, investigators have proposed a specific scale for the 200 mg/m2 (Table 2). In an attempt to reduced the grading of oxaliplatin neurotoxicity [89, 90]. This gradnausea and vomiting, the infusion was prolonged to six ing (Table 3) is the current standard in recent and onand 12 hours for doses above 60 mg/m2, but this toxicity going oxaliplatin clinical research. The dose of 130-135 was not influenced by the duration of infusion [89]. mg/m2 oxaliplatin given over two hours every three Subsequently, systematic prevention of nausea using anti weeks was recommended for further phase II trials. In 5-HT3 antiemetics has significantly decreased the se- these phase I and phase II studies, particular attention verity of this toxicity, with less than 4% grade 3 nausea was paid to assessing whether there was any ototoxicity and vomiting in recent phase II and phase III trials. with oxaliplatin, without a single report of such side Grade 3 diarrhea was reported in seven patients receiv- effect. ing doses of 150 mg/m2 or greater. The most constant acute side effect was a transient Alternative administration modalities and schedules peripheral neuropathy characterized by paresthesia and dysesthesia in hands, feet and the peri-oral area, trig- A five-day oxaliplatin continuous infusion administragered and/or enhanced by contact with cold. Some tion was studied by Caussanel et al. [90]. Thirteen and 12 patients reported laryngo-pharyngeal dysesthesia when patients received either constant or circadian rhythmswallowing cold food or drink. Electromyograms were modulated infusion, respectively. Intra-patient dose esperformed in several patients and showed a sensitive calation was performed starting at 100 mg/m2 going up neuropathy with normal nerve conduction. These symp- to 200 mg/m2. The rate and intensity of the side effects toms were often observed during oxaliplatin infusion, in this study were similar to those observed with short 1 (2.5)

1(5)

5(18)

4(34)

1059 infusion, with grade 1-2 hematological toxicity in about 20% of cycles. Mild and severe neurotoxicity occurred more frequently in the flat than in the chronomodulated infusion (28% versus 2% of cycles, respectively). The neurosensory toxicity remained the dose-limiting event when oxaliplatin was given as continuous infusion. The doses of 125 and 150 mg/m2 oxaliplatin were recommended for constant and chronomodulated continuous infusion over five days every three weeks, respectively, and give the basis for further clinical trials comparing flat versus chronomodulated delivery of oxaliplatin in combination with 5-FU. Severe nausea and vomiting were less frequently observed with continous infusion, and with the systematic use of a new anti 5-HT3 antiemetics pretreatment. Pharmacokinetics The short-term and cumulative pharmacokinetic parameters of oxaliplatin have been investigated in several studies. In the study conducted by Bastian et al. [91], 130 mg/m2 oxaliplatin was administered as a two-hour intravenous infusion without any pre- or post-hydration in patients with varying degrees of renal excretory dysfunction. Fourteen patients entered the study with normal renal function (creatinine clearance (CrCl) > 60 ml/min) and ten patients had mild to severe impaired renal function (median CrCl 38 ml/min ranging from 12 to 57) due to previous cisplatin treatment in six patients (cumulative doses of cisplatin: 600 mg/m2, ranging from 100 to 1390). Total and ultrafiltrable plasmatic Pt values were measured by atomic absorption spectrometry. At this dose, the overall toxicity was mild in patients with both normal and impaired renal function. The plasma pharmacokinetic behavior of oxaliplatin was similar to that of cisplatin with a two-compartment distribution for both total and ultrafiltrable Pt, and a large volume of distribution (Table 4). After a two-hour infusion, 50% of the Pt accumulated in red blood cells, and 50% remained in the plasma (about 67% bound to proteins and 33% ultrafiltrable). Mean total and ultrafiltrable plasma clearance and 48-hour urinary recovery of oxaliplatin were significantly reduced in patients with renal dysfunction. Consequently, the AUC of ultrafiltrable Pt was increased in this group of patients as compared to patients with normal renal functions. However, no degradation of the CrCl-values and no increase of the overall toxicity was observed in patients with initial impaired renal function treated at this dose level. This study indicated that the dose of 130 mg/m2 oxaliplatin as a two-hour infusion can safely be administered in patients with impaired renal function without dose-adjustment and without any pre- and post-hydration. Recent studies using a very sensitive method for Pt determination (Inductively Coupled Plasma Mass Spectrometry - ICPMS, [92]) have assessed oxaliplatin pharmacokinetics, and whether oxaliplatin may accumulate

Table 4. Comparison of oxaliplatin pharmacokinetic parameters in patients with normal and impaired renal function.3 Normal renal function (TJ = 14 pts) Peak plasma level (vg/ml) Total platinum Ultrafiltrable platinum AUC (ug/ml/h) Total platinum Ultrafiltrable platinum Clearance (1/h) Total platinum Ultrafiltrable platinum T 1 / 2 a(h) Total platinum Ultrafiltrable platinum

Impaired renal function1" (n = 10 pts)

P-values (Mest)

4.9 ±0.3 2.3 ±0.4

>0.05 >0.05

102.8 ±6.6 9.8 ±0.9

119.7 ± 18.9 15.2 ± 1.4

>0.05 0.004

2.4 ±0.2 26.5 ±2.1

1.9 ±0.2 15.6 ± 1.7

>0.05 0.0009

5.1 ±0.2 2.1 ±0.2

0.43 ±0.1 0.35 ±0.1

0.69 ± 0.3 0.49 ± 0.2

>0.05 >0.05

T,/ 2 P(h) Total platinum Ultrafiltrable platinum Vd (volume of distribution; in 1) Total platinum Ultrafiltrable platinum Percentage urinary excretion of platinum at 48 hours

38.7 ±2.4 24.2 ± 6.9

54.9 ± 8.9 27.7 ±4.1

>0.05 >0.05

70.5 ±4.4 330.1 ±40.9

58.1 ±2.8 240.8 ±31.1

>0.05 0.02

> 50%

< 30%

-

a

Results are expressed as mean ± SEM. From Bastian et al. [91]. Mean creatinine clearance was 38 ml/min ranging from 12 to 57 ml/min. b

after repeated injections [37, 93]. In these studies, the Pt Cmax was 1.21 ± 0.1 ug/ml and the AUC was 11.9 ± 4.4 ug/ml.h after injection of 130 mg/m2 oxaliplatin over two hours. Oxaliplatin displayed a large volume of distribution (582 L) and a triexponential ultrafiltrable platinum half-life decline (T1/2a: 0.28 hours, T1/2p: 16.3 hours, and TI/ 2 Y : 273 hours). Most of the Pt was recovered in the urine (53.8%) over five days although 2.1% was recovered in the feces. Gamelin et al. [37] measured residual plasma and intra-erythrocyte levels of Pt in 17 patients receiving iterative intravenous injection of 130 mg/m2 oxaliplatin as a two-hour infusion (combined with 5-FU) every three weeks. They found that unlike cisplatin, which rapidly accumulates as both free and bound Pt in the plasma, oxaliplatin does not accumulate in the plasma after repeated administrations. Interestingly, Bastian et al. [91], Graham et al. [93], and Gamelin et al. [37] have observed progressive and significant accumulation of Pt in red blood cells with a terminal Pt half-life close to that of erythrocytes. While the binding of oxaliplatin to proteins in the plasma is in many extents similar to that of cisplatin, the partitioning of Pt in red blood cells appears to be unique for oxaliplatin. As indicated previously, in vitro studies have shown that most of the intra-erythrocyte ultrafiltrable Pt remained non-exchangeable. However, those differences in the long-term intracellular partitioning between oxaliplatin and cisplatin are intriguing and could account, at least in part, for the toxicological differences (especially for

1060 cumulative neurotoxicity) between those two platinum drugs after repeated injections. Clinical cumulative toxicity profile in phase II trials Most phase II studies of oxaliplatin were conducted at the recommended dose of 130 mg/m2 as a short intravenous infusion (two to four hours) every three weeks [94-97]. Those studies have shown that the acute toxicity profile of repeated injections of oxaliplatin was similar to that initially described in early phase I studies. However, nausea and vomiting have been considerably reduced by systematic pretreatment with 5-HT3 antagonists in phase II—III clinical studies. Those studies have further confirmed that unlike cisplatin, repeated injections of oxaliplatin do not induce renal dysfunction or ototoxicity. The risks of developing a moderate to severe grade 2-3 neuropathy (specific scale) have been estimated at 10% after six cycles (780 mg/m2) and at 50% after nine treatment cycles (1170 mg/m2) of oxaliplatin given at the recommended dose and schedule of 130 mg/m2 every three weeks. However, unlike the severe cumulative neuropathy induced by cisplatin, the neuropathy induced by oxaliplatin did not worsen after treatment discontinuation and was fully reversible after six to eight months in 82% of patients [98]. This toxicity was only sporadically associated with major functional impairment and was seldom the exclusive reason for treatment discontinuation. Increasing clinical experience with the drug showed that investigators familiar with oxaliplatin often manage this toxicity by dose reduction rather than treatment delay.

Clinical activity in colorectal cancer Unlike cisplatin, carboplatin and many other anticancer drugs that did not show any significant and reproducible activity against colorectal cancers in clinical trials [99, 100], oxaliplatin demonstrated antitumoral activity alone and in combination with 5-FU in preclinical and clinical studies. Unorthodox aspects of the development of oxaliplatin were that (1) the bulk of early relevant clinical information concerning oxaliplatin activity has been obtained in patients with advanced colorectal cancers and (2) that substantial evidence of its activity was gathered when used in combination with protracted infusion of 5-FU combined with folinic acid, preceding the formal demonstration of its single agent activity in this disease. High response rates, including complete responses, were associated with long progression free and overall survivals in patients with 5-FU pretreated or refractory colorectal cancers. Oxaliplatin demonstrated antitumoral activity, in vitro and in vivo, against several human colon cancer lines [60]. Interestingly, the activity of oxaliplatin was maintained in human colon cancers with either primary [70] or acquired resistance to 5-FU [60]. Additional evidence arises from the NCI COMPARE's differential profile

[15, 58] and data from Pendyala [36], confirming the cytotoxic superiority of oxaliplatin to cisplatin in colorectal cancer. Interestingly, in both preclinical and clinical study, additive or synergistic antitumoral effects were observed in combination with 5-FU including 5-FU sensitive and 5-FU resistant colorectal cancer cells. Genetic mismatch repair defects are implicated in the carcinogenesis of non polyposis hereditary colorectal cancer [101] and many other tumors such as, ovarian, endometrial cancer etc... [102]. Moreover, a microsatellite instability/mismatch repair deficient phenotype is increasingly prevalent with tumor progression [103]. Recent work by Fink et al. [86] might have given a mechanistic basis for understanding the specific advantage of oxaliplatin over cisplatin in mismatch repair deficient colon cancer cells. Furthermore, mismatch repair deficient colon cancer cell lines often over express thymidylate synthase, which makes cells particularly resistant to 5-FU [104]. Therefore, the mismatch repair phenotype and the thymidylate synthase expression warrant exploration as possible relevant mechanisms explaining the synergy between oxaliplatin and 5-FU in colorectal cancers [84]. Single agent To date, five clinical trials with single agent oxaliplatin have been conducted in patients with both previously untreated and 5-FU-refractory advanced colorectal cancers. Previously untreated patients A phase II study was conducted by Becouarn et al. [94]. A total of 39 patients received a two-hour infusion of 130 mg/m2 of oxaliplatin every three weeks. Out of the first 25 evaluable patients, an objective response rate of 24% was observed along with 36% disease stabilization. The median duration of response wasfivemonths (range 5-9+), the median time to progression was four months (range 1-9+) and the median overall survival was 12 months (range 1-16). Another phase II study performed by Diaz-Rubio et al. [95] in 25 patients showed an objective response rate of 20%. The median duration of response, time to progression, and overall survival were six, four, and 14.5 months, respectively (Table 5). These phase II studies showed that oxaliplatin can be considered as an active drug in previously untreated ACRC patients. Interestingly, the overall objective response rate of 20% for oxaliplatin was in the range of the rates observed with either single agent 5-FU, raltritexed or irinotecan. 5-FUpretreated patients Two phase II studies using a short two-hour infusion of oxaliplatin at a dose of 130 mg/m2 were conducted in a total of 109 patients previously exposed and mostly refractory to 5-FU [96]. Tumor responses were evaluated by an independent radiological review. An overall response rate of 10% was observed. Those

1061 Table 5. Activity of single agent oxaliplatin" in patients with advanced colorectal cancers (phase II studies).

Number of patients Evaluable Included Response in % (95% CI) Stabilization (%) Median survival (months)

Previously untreated patients

Patients previously treated with 5-FU

Becouarn [94]

Diaz-Rubio [95]

Machover [96]

Diaz-Rubio [96]

Levi [97]

25 25 20 32

53 58

48 51

29 30

11.3(6.0-19.8) 41.5

10.4(5.0-19.0) 41.6

10(5.0-18.0) 24.1

25 27

24 (9.3-45) 36 >5

14.5

8.5

-

9

Doses: 130 mg/m2/cycle as a two-hour infusion every three weeks.

patients with clinical responses had a median time to disease progression of six months and a median survival of 14.5 months in the study by Machover et al., while in the study conducted by Diaz-Rubio et al. [96], the overall response rate was 10% with a median time to disease progression of 4.5 months. Similarly, in the study performed by Levi et al. [97] with five-day chronomodulated oxaliplatin, the overall response rate was also 10%. Three responses were observed in patients with hepatic metastases that progressed while receiving 5-FU/folinic acid on a five-day schedule, a further 24% to 42% of patients had disease stabilization. The median progression-free survival was five months and the median survival was about 10 months. The results from the five studies show that single agent oxaliplatin has clinical activity against both 5-FUresistant and previously untreated colorectal cancers. Combinations with 5-FU Preclinical data aiming to explain the activity of oxaliplatin in colorectal cancer have been slow to build up. Preclinical information is still accumulating while several hundred patients have already been treated. Early evidence of oxaliplatin activity in combination with 5-FU was provided by clinical studies performed by Levi using several chronomodulated oxaliplatin/5-FU/FA schedules. At that time, the role of chronotherapy delivery was emphasized and it took quite a long time to acknowledge the specific contribution of oxaliplatin itself in the combination. Preclinical studies were subsequently performed by Raymond et al. [60] showing that, in vitro and in vivo, oxaliplatin has synergistic antitumoral activity in combination with 5-FU and non-classical thymidylate synthase inhibitors in human colon cancer xenografts. Since 5-FU and oxaliplatin were both studied with an in vitro 48-hour exposure, this study showed a direct pharmacological interaction between the two drugs independently of any chronomodulated schedule. The de Gramont's schedule combining a twohour short infusion of oxaliplatin with a fortnightly 48hour high-dose bolus/infusion sequence of 5-FU/FA (LV5FU2) confirmed the antitumoral activity and the safety profile of the combination, independently of chronomodulation [105,106].

Previously untreated patients (Table 6) Treatment every three weeks: A phase II study by Levi et al. evaluated the activity of oxaliplatin in combination with 5-FU/FA, using afive-daychronomodulated infusion given every three weeks [107]. Doses of 5-FU ranged between 3000 and 3500 mg/m2/cycle. The 100 mg/m2 dose of oxaliplatin given in the first cycle was escalated in the second cycle if no grade 2 toxicity was observed. A total of 47 previously untreated patients were evaluable, with a response rate of 58%, including 10% complete responses. Disease stabilization was observed in 30% of patients. The median survival was 15 months. Based on these results two phase III studies comparing a flat to chronomodulated delivery, were performed by the same group. The first study, involving 92 previously untreated patients, was discontinued after the documentation of a partial chemical inactivation of oxaliplatin by the basic pH of 5-FU in the infusion tubing (flat infusion arm). This disturbed the valid interpretation of the difference in response rates [108]. The second study was conducted in 186 patients using separate infusion catheters (93 patients in each arm) [109]. In this study, despite significant differences noted in the overall response rates in the chronomodulated arm (51% in the chronomodulated versus 29% in the flat arm), no differences in disease free and overall survivals was observed [109]. Interestingly, both treatment modalities led to post-chemotherapy metastasectomy with curative intent that allowed 14.5% of patients to achieve a complete response after surgery. The important question of the role of oxaliplatin in this combination has finally been addressed prospectively in a multicenter European phase III study, recently reported by Giachetti et al. [110]. This study compared 5-FU/FA administered every three weeks to the same regimen plus oxaliplatin. 5-FU and FA were given at doses of 3500 mg/m2 and 1500 mg/m2/cycle as a fiveday chronomodulated infusion, respectively, in both arms. Oxaliplatin was given at the dose of 125 mg/m2/cycle given on day 1 over six hours. Responses to treatment were reviewed by an independent panel of radiologists. Among 100 patients treated in each arm, overall response rates of 12% and 34% in the 5-FU/FA and 5-FU/FAoxaliplatin arms were reported, respectively. The median progression-free survival was statistically improved in

1062 Table 6. Activity of oxaliplatin in combination with 5-FU and folinic acid in previously untreated patients with advanced colorectal cancer (phase II—III studies). No.

Dose and schedule

FA

Stabilization Median

Responses

f

01

pts

Phase II Levi[107]

46

Levi[114]

90

Phase III Levi [108]

47 45

Levi[109]

93 93

Giachetti[110]

100 100

deGramont[117]

200 200

Total

813

(mg/m /cycle)

Oxaliplatin (mg/m2/cycle)

5-FU (mg/m2/cycle)

125-q4w (CMI - five days) 100-q2w (CMI - four days)

3500-q3w 1500 (CMI - five days) 28-4000 - q2w 1200 (CMI - four days)

100-q3w (CI - five days) 100-q3w (CMI - five days) 125-q3w (CI - five days) 125-q3w (CMI - five days) 125-q3w (six-hour infusion) -

3000 - q3w (CI - five days) 3000 - q3w (CMI - five days) 3000 - q3w (CI - five days) 3000 - q3w (CMI - five days) 3500-q3w (CMI - five days) 300 - q3w (CMI - five days) 85-q2w 2000 - q2w (two-hour infusion) (CI - two days) 2000 - q2w (CI - two days)

-

-

Complete Overall response (%) response

(%)

survival (months)

58

5

32

15

67

3

NA

19

1500

32

2

21

19(/> = 0.03)

1500

53

3

33

23

1500

29

3

40

16.9

1500

51

5

30

15.9

1500

34

NA

NA

17.6

1500

12

NA

NA

19.4

400

51.2

NA

NA

NA

400

22.6

NA

NA

NA

21-40

15-23

-

34-67

Abbreviations: MI - chronomodulated continuous infusion; CI - continuous infusion.

patients receiving oxaliplatin (8.7 versus 6.1 months, P = 0.04). The median overall survivals were 17.6 and 19.4 months in 5-FU/FA and 5-FU/FA/oxaliplatin arms, respectively. A recent update on this trial sheds light on the survival equivalence of both arms when analyzing crossover and metastasectomy after chemotherapy [111]. Crossover to oxaliplatin 5-FU/FA was recommended, and implemented in 57 of 100 of patients of the 5-FU/FA arm, with 17.5% of them obtaining objective responses. Furthermore 69 of 200 patients undervent metastasectomy, 35 in the 5-FU/FA arm and 34 in the oxaliplatin arm. Complete resection was achieved in 44 of them, but is of note that 16 metastasectomies were done after crossover chemotherapy. The survival in the metastasectomised patients exceeds 35 months [111]. Treatment every two weeks: Preliminary work by Brienza et al. [112], on the chronomodulated delivery of oxaliplatin/5-FU/FA every two weeks (four days on/10 days off) led to a monocentric phase II trial, reported by Berthault-Cvitkovic et al. [113]. In an attempt to evaluate chronomodulated delivery in a biweekly schedule, Levi et al. [114] enlarged this experience to a multicenter phase II study. The study combined 5-FU/FA and oxaliplatin every two weeks. Doses of 5-FU ranged from 2800 to 4800 mg/m2, and the dose of oxaliplatin was 100 mg/m 2 , given over four days. Sixty out of the 90 (67%) patients experienced objective responses, with a median overall survival of 19 months.

Those studies showed that 5-FU/FA and oxaliplatin combinations were highly active in untreated patients with advanced colorectal cancer, with response rates ranging from 34% to 67%. Most importantly, this combination yields high median overall survivals, ranging from 15 to 20 months and comparing favorably to those reported with 5-FU alone or modulated by any other agent, such as FA, a-interferon, PALA or methotrexate [115]. Furthermore, an European multicenter phase III trial was recently performed, investigating the potential benefits of oxaliplatin when added to the biweekly 5-FU/FA administration (LV5FU2) developed by de Gramont et al. [116]. This study involved 420 patients randomized to receive 200 mg/m2 of leucovorin, followed by 400 mg/m2 of 5-FU bolus and 600 mg/m2 in continuous infusion for two days every two weeks, with or without 85 mg/m2 of oxaliplatin on day 1. Both arms were well balanced for primary site (colon/rectum), performance status, the number of metastatic sites, and prior adjuvant chemotherapy. The response rates evaluated by independent radiological reviewers showed 51.2% and 22.6% responses in the patients treated with and without oxaliplatin, respectively (P < 0.05). In addition, significant benefit in terms of progression-free survival was obtained in patients receiving oxaliplatin in combination with LV5FU2 (8.7 months) versus patients receiving LV5FU2 alone (6.1 months) [117]. This clinical study also confirmed previous preclinical and clinical experiences

1063 Table 7. Activity of oxaliplatin in combination with 5-FU and folinic acid in previously treated patients with advanced colorectal cancer (phase II studies). No. of pts

Short infusion DeGramont[105] DeGramont[106] Andre [119]

Continuous infusion Levi[107]

Oxaliplatin (mg/m2/cycle)

12

130 - q4w (two-hour infusion) 46 100 - q 2 w (two-hour infusion) 24 a 80 - q2w (two-hour infusion) 20" 80 - q2w (two-hour infusion) 47

Bertheault-Cvitkovic [113]

37

Garufi[118]

25 a

Total

Dose and schedule

211

5-FU (mg/m2/cycle)

FA Stabilization Median Responses survival (mg/m2/cycle) (%) (months) Overall Complete response (%) response

4000 - q2w (48-hour infusion) 1000 3^1000 - q2w (48-hour infusion) 400 2000 - q2w (48-hour infusion) 1000 3000 - q2w (48-hour infusion)

125-q4w (CMI - five days) 100-q2w (CMI -fourdays) 100-125 q2-3w (CMI - five days)

3500-q3w 1500 (CMI - five days) 24-4800 - q2w 1200 (CMI - four days) 3500-q2-3w (CMI - five days)

-

-

-

25

0

-

-

46

1

46

17

21

37.5

-

35

20

-

58

1

19

15

40

1

51

17

28

0

-

12

21-58

19-51

12-17

Abbreviations: CMI - Chronomodulated continuous infusion; CR - patients with complete responses. 5-FU refractory patients exclusively.

a

showing additive or synergistic effects between oxaliplatin and 5-FU in colorectal cancers. Previously treated patients (Table 7) Combinations of oxaliplatin with 5-FU and folinic acid have been evaluated in several phase II studies conducted by both de Gramont's and Levi's groups (Table 7). Doses of oxaliplatin ranging from 125 to 130 mg/m2, either as a two-hour or a five-day chronomodulated infusion every three to four weeks [105,107,118], were combined with a high dose of 5-FU (3500-4000 mg/m2). The dose-intensity of these regimens was further increased by repeating the injections of 80-100 mg/m2 of oxaliplatin either as a two-hour [117, 119] or as a fourday chronomodulated infusion [113] every two weeks, with 2000 to 4800 mg/m2 of infusional 5-FU. Globally, these phase II studies showed that oxaliplatin increased only moderately the overall toxicity of high-dose 5-FU. The results seem to indicate that short-term (two hours), flat or chronomodulated continuous infusion administration schedules are equally effective in terms of response rates and progression-free survivals reported. The overall response rates ranged between 25% and 58%. Interestingly, complete responses were observed with both short and chronomodulated schedules, with complete response rates ranging from 3.5 to 5%. Overall progression-free survivals ranged from 5.8 to 11 months, and overall survivals ranged from 12 to 17 months. Response rates were similar in each different metastatic site. For example, in liver and lung metastasis, the response rate was 44% and 46%, respectively [106]. Furthermore, the ability of oxaliplatin to overcome clinical resistance to 5-FU has been formally demon-

strated by Levi et al. [107], de Gramont et al. [106], Garufi et al. [118], and Andre et al. [119], who added oxaliplatin to the same 5-FU/FA schedule under which patients had previously progressed. Response rates of 27% to 46% were obtained in clinical trials where each patient was his own control. The clinical significance of these results was convincing enough to lead to the registration, in France in 1996, of oxaliplatin for the treatment of 5-FU pretreated patients. Compassionate use data The modality of delivery and schedule of 5-FU/FA might be important factors in oxaliplatin activity, efficacy, and toxicity. Since most of the published experiences were provided either by Levi and de Gramont using original 5-FU/FA schedules, one of the current review authors (E.C.) decided to investigate the impact of oxaliplatin in currently used 5-FU/FA regimens by collecting data from the European and French compassionate experiences. Ongoing trials using a wide variety of 5-FU/FA schedules and doses (bolus, weekly or daily infusion: 24 hours, 48 hours, five days, protracted infusion, oxaliplatin given every two or three weeks) were aimed at assessing the possible differences in the pharmacodynamics of toxicity and activity in the different 5-FU/FA modalities when combined with oxaliplatin. The European compassionate use experience and French Extended Access Program were used to partially answer this important question. Although compassionate use patient cohorts are of limited value as clinical research tools, a complete careful analysis may help to define therapeutic advances in a realistic practice setting.

1064 Table 8 Activity of oxaliplatin in combination with 5-FU ± FA in patients with advanced colorectal cancer refractory to 5-FU ± FA. Results of the European Compassionate Use (ECU) and French Extended Access Program (FEAP) framework experiences. ECU cohort, [120]

Overall response rate (%) Time to progression (months) Overall survival (months)

FEAP cohort"

q two weeks (n = 49)

q three weeks (n = 62)

q two weeks (« = 36)

q three weeks (n = 308)

25 5.4 (2.7-8.0) 10.6(7.9-13.5)

21 4.0 (3.4-5.0) 7.7(5.6-9.8)

36.1 5.4 (4.9-6.9) 11.1(8.7-16.3)

13.3 4.2(3.7-4.6) 10(9.2-11.3)

' E. Cvitkovic et al. (personal communication).

In the European compassionate use cohort, a large variety of 5-FU doses, administration modalities and schedules, with oxaliplatin were given every two or three weeks to 206 patients [120]. Where such radiological evidence was available (for 111 patients), it was possible to assess both resistance to previous 5-FU/FA and the activity of oxaliplatin when added to 5-FU ± FA. In these patients, a 26% response rate was observed. Biweekly oxaliplatin administration and high dose intensity infusional 5-FU/FA schedules seemed superior to bolus 5-FU or q three weeks oxaliplatin administration. Toxicities were limited to 5-FU and related to its specific administration modalities. In addition, the analysis of the 490 patients treated in the French Extended Access Program (EAP) framework, has also recently been completed. A total of 370 patients were found to be resistant to 5-FU and were treated with a wide variety of 5-FU schedules, both before and after oxaliplatin-based treatment. When combining both compassionate use experiences, a median survival of 10 months was observed in 481 patients progressing while receiving 5-FU/FA treatment after oxaliplatin was added to 5-FU. No difference was observed when the same 5-FU schedule was maintained, or changed upon oxaliplatin addition (Table 8). Data generated from the French and European Compassionate Use experiences were consistent, and showed that in almost all 5-FU/FA regimens where patients had 5-FUrefractory colorectal cancer, clinical efficacy was improved by oxaliplatin. Of course, the combination of oxaliplatin and 5-FU remains palliative for most patients with advanced colorectal cancer. Nevertheless, the high response rate induced by the oxaliplatin/5-FU combination may increase the number of patients who are amenable to hepatic or pulmonary metastasectomy. In the study by BertheaultCvitkovic et al., where 26% of patients underwent surgical resection of hepatic metastasis, there was a 17.8 months median overall survival [113]. Similar results were reported by Giacchetti et al. [121] in a cohort of 351 patients with initially unresectable liver metastases and treated with the oxaliplatin/5-FU/FA combination. In this cohort, 22% of patients underwent post-chemotherapy metastasectomy. The median overall survival for these patients was 37 months. These results suggest that the oxaliplatin/5-FU/FA combination has the potential for improving the overall survival of patients with

advanced colorectal cancers, increasing the possibility of secondary metastasectomy, as evidenced in the phase III update of Giacchetti et al. [111]. Ongoing studies A phase III study comparing the biweekly oxaliplatin/ 5-FU/FA chronomodulated administration developped by the Levi group to the biweekly oxaliplatin/5-FU/FA combination schedule of de Gramont et al. [117] in previously untreated patients is currently being carried out within the EORTC. In previously treated patients, phase II randomized trials exploring oxaliplatin given as a short infusion at doses of 85 mg/m2 every two weeks or 130 mg/m2 every three weeks in combination with several 5-FU modalities (bolus or infusion, high or low dose FA modulation) are ongoing in Europe and the USA. A French randomized phase II open trial is comparing 85 mg/m2 of oxaliplatin plus 200 mg/m2 of CPT-11 given every three weeks [141] to the successive alternations of this combination plus CPT-11/LV5FU2 given simultaneously [122]. In addition, results in advanced diseases generated interest in oxaliplatin/5-FU/ FA for the adjuvant treatment of colon cancer. The prospective evaluation of the combination in this setting against 5-FU/FA is planned.

Clinical activity in other tumor types Ovarian cancer Single agent The results of preclinical studies showed partial or no cross-resistance between oxaliplatin and cisplatin in a number of human tumor models involving ovarian carcinomas, which suggested that oxaliplatin might be further evaluated in phase II and III clinical trials. Two reports are available regarding oxaliplatin as a single agent in patients with cisplatin-pretreated advanced ovarian cancer. In the first study, Misset et al. [123] observed four of 14 partial responses (26% response rate). In a subsequent study, conducted by Chollet et al. [124], a total of 35 patients previously exposed to cisplatin were treated with single agent 100-130 mg/m2 oxaliplatin as a short intravenous infusion every three weeks. Among the 31 evaluable patients, nine (29%) partial

1065 responses were observed including six of 13 (46%) in potentially platinum-sensitive and three of 18 (17%) in platinum-resistant patients according to Markman's criteria. The median overall survival of 12 months gave the basis for further exploration of oxaliplatin in combination chemotherapy studies. Combination with cyclophosphamide A recent phase II—III study reported by Misset et al. [125] has compared 1000 mg/m2 cyclophosphamide in combination, either with 130 mg/m2 oxaliplatin or 100 mg/m2 cisplatin every three weeks for six courses in 182 patients with previously untreated advanced ovarian carcinoma. In this study, the overall response rates were 51.5% and 65% in patients randomized to receive oxaliplatin and cisplatin, respectively. With a median followup of 32 months, no significant differences were observed in progression-free or overall survival in the two arms. However, hematological toxicities (10% versus 29%) and delayed cycles due to these toxicities (18% versus 37%) were significantly reduced in the group receiving oxaliplatin compared with the cisplatin arm. Nausea and vomiting were also reduced in the oxaliplatin arm. As expected, acute mild dysesthesias were frequently observed in patients receiving oxaliplatin, but the rate of severe (grade 3 and 4) neurotoxicity was significantly less frequent in patients treated with oxaliplatin (2% versus 0%). Based on these results, the authors suggest that oxaliplatin and cisplatin may have a similar level of efficacy than cisplatin in first-line chemotherapy of advanced ovarian cancer, with a safe toxicity profile. Combinations with cisplatin The combination of oxaliplatin and cisplatin has been tested in 24 patients with advanced ovarian carcinoma previously exposed to cisplatin-based chemotherapy. The concept of combining two platinum compounds despite their common neurotoxic potential may be considered quite provocative, especially in patients previously exposed to cisplatin-based regimens. The concept was initially based on the notion of dose-intensity and on the preclinical data that showed the synergy between oxaliplatin and either carboplatin or cisplatin in L1210 leukemia in vivo [68] and in cultured ovarian cancer cells [15] in vitro. In a phase I—II study, 90-150 mg/m2 oxaliplatin was combined with 60-110 mg/m2 of cisplatin every three or four weeks [126]. For patients who were potentially sensitive and refractory to cisplatin according to Markman's criteria, the overall response rates were 75% and 25%, respectively [127]. The addition of high dose epirubicin (90-110 mg/m2) and ifosfamide (4.5-6 g/m2) to this regimen resulted in an increased response rate (70%) in a further 19 patients who were pretreated, but not resistant to cisplatin [128]. Hematological toxicity was high in this four-drug combination. Moreover, in these 'biplatin-regimen' experiences, conducted in patients who had been heavily pretreated with cisplatin and who had neurotoxicity on inclusion, there

was a dose-limiting severe peripheral neurotoxicity in 43% of patients. Combination with paclitaxel A pilot study by Kalla et al. [129], has tested the toxicity of the oxaliplatin/paclitaxel combination in patients with ovarian carcinomas previously treated with cisplatin. An interim analysis showed that recommended doses of 130 mg/m2 of oxaliplatin and 175 mg/m2 of paclitaxel (three hours), can be safely combined with little or only moderate hematological and neurological toxicity in patients previously treated with cisplatin. The occurrence of three (17%) complete and six (33%) partial responses among the 18 evaluable patients warrants further investigation of this combination in ovarian cancer. Combination with oxaliplatin, cisplatin, and paclitaxel An ongoing program is testing this three drug combination in patients with recurrent ovarian cancer who relapse with a long disease free interval after first-line chemotherapy [130]. Five previously-treated patients who relapsed at least 18 months after primary treatment, were treated with 100 mg/m2 of oxaliplatin, 80 mg/m2 of cisplatin, and a 24-hour infusion of 135 mg/m2 paclitaxel with G-CSF. Brief (three to four days) severe neutropenia was the most serious acute toxicity. A transient cumulative neuropathy was seen in all patients after = three cycles of treatment. Two complete and one partial responses were seen along with prolonged stabilization in two patients. Ongoing studies A French open phase II multicentric study is ongoing in patients with ovarian cancer previously treated with cisplatin and/or taxanes [131]. Preliminary report shows objective response in nine of 33 (27%) evaluable patients with eight of 17 (47%) and one of 13 (7.5%) in platinum sensitive and refractory patients, respectively. Furthermore, a recently completed EORTC randomized phase II study in patients with cisplatin refractory ovarian cancer compared oxaliplatin (130 mg/m2 q three weeks) to paclitaxel (three-hour infusion at 175 mg/m2 q three weeks) [132]; its results are awaited. Activity in other malignancies Single agent Data on the clinical activity of oxaliplatin in several tumor types are often scarce. Nevertheless, single agent data is available on advanced breast cancer [133], nonsmall-cell lung cancer [134], non-Hodgkin's lymphoma (NHL) [135], head and neck squamous-cell carcinoma [136] and malignant astrocytoma [137]. As shown in Table 9, recurrent head and neck cancer was marginally sensitive to oxaliplatin and malignant astrocytomas were not sensitive to oxaliplatin. Interestingly, three responses in breast cancer patients were initially described during phase I trials [88, 90]. The excellent tolerance profile and

1066 Table 9. Activity of single agent oxaliplatin in phase II studies outside colorectal and ovarian cancers. Author/Reference

Tumor type

Previously treated/untreated

Responder/evaluable patients (%)

Response duration (month)

Rotarsky[135] Degardin[136]

Non-Hodgkin's lymphoma Head & neck cancer

22/0 17/23

Monnet[134] Garufi[133] Maugard-Louboutin [137]

Non-small-cell lung cancer Breast cancer Malignant astrocytomas

0/15 14/0 a 0/14

9/22(41) Treated 1/17(6) Untreated 3/23 (13) 2/15(13) 3/14(21.4) 0

14(3-40) 2 2,3,4 6, 11 NA -

1

Anthracycline resistant.

Table 10. Ongoing and planned studies. Indication Ongoing studies Colon cancer, pretreated Colon cancer, pretreated GI malignancies, pretreated GI tumors NSCLC, untreated

Phase

Drugs

HI

L V 5 F U 2 alone o r with L - O H P 85 m g / m 2 L-OHP 85 mg/m2/+ CPT-11 200 mg/m2 q 3 w vs. idem alternated with CPT-11 /LV5-FU2 L-OHP/CPT-11 q 2 weeks L-OHP/raltritexed L-OHP/navelbine L-OHP 135 mg/m2 Paclitaxel 175 mg/m2 in three hours L-OHP 100-130 mg/m2 on day 2 Cisplatin 80-100 mg/m2 on day 2 Paclitaxel 135 mg/m2 on day 1 24 hours c.i. L-OHP 130 mg/m2 q 3 w vs. paclitaxel 175 mg/m2 q 3 w as three-hour infusion L-OHP Carboplatin/L-OHP

Ovarian cancer, pretreated

I—II

Ovarian cancer, pretreated

I — II

Ovarian cancer, pretreated Ovarian cancer, pretreated Solid tumors Planned studies Breast cancer, taxane pretreated Colon cancer, adjuvant Colon cancer, pretreated Colon cancer, untreated Gastric cancer, untreated Lung cancer Ovarian cancer, untreated Ovarian cancer, untreated Pancreas Pancreas Pancreas cancer Prostate cancer Solid tumors

II II I II III III II II II II II — III II II II II I—II

L-OHP130mg/m 2 q3w 5-FU 4-d c.i. q 3 w L-OHP/FU/FAvs. FU/FA L-OHP/FU/FA chrono vs. L-OHP/FU/FA (LV5FU2) L-OHP/CPT-11 q two weeks L-OHP/5-FU/FA (LV5FU2) q three weeks L-OHP L-OHP/cisplatin/paclitaxel Paclitaxel/ L-OHP vs. paclitaxel/carboplatin 5-FU 5-d alone vs. L-OHP alone vs. combination of both L-OH P/gemcitabine L-OHP/CPT-11 q two weeks L-OHP alone vs. LOHP/5-FU (c.i.v.) q three weeks L-OHP/topotecan L-OHP/gemcitabine L-OHP/pachtaxel

lack of hematological toxicity motivated Garufi et al. [133] to explore oxaliplatin activity in 14 patients with anthracycline-resistant breast cancer. Three partial responses and one stable disease were seen in patients with breast cancer. In addition, a small phase II trial in NSCLC by Monnet et al. [134] reported in 33 evaluable patients showed one complete reponse and four partial responses for overall reponse rate of 15%. The activity of oxaliplatin in non Hodgkin's lymphoma [135] should be mentioned. Amongst 22 NHL heavily pretreated patients, an overall response rate of 41%, with long median duration responses of 14 months (range 3-40) have been reported. Most responses were seen in the 15 low-grade NHL patients.

Combination with carboplatin Preclinical activity in cisplatin-resistant L1210 leukemia in vivo showed synergy between oxaliplatin and carboplatin [68]. A review of 14 patients treated with this combination by Llory et al. [138], elicited only one response, with high hematotoxicity (mainly thrombocytopenia) when doses of 400 mg/m2 of carboplatin and 100 mg/m2 of oxaliplatin were given. Since the patients were heavily pretreated and many had abnormal organ functions at baseline, the feasibility of this combination needs to be reviewed; this is happening in one ongoing pharmacokinetically-guided phase I trial [139].

1067 Combination with irinotecan In vitro and in vivo results have recently been obtained by Zeghari-Squalli et al. for combinations of oxaliplatin and irinotecan in HT29 colon cancer cells [140]. The non-overlapping toxicity and the common spectra of activity in colon cancer led Cvitkovic et al. [141] to initiate a phase I trial of the oxaliplatin/irinotecan combination in patients with digestive malignancies previously treated with 5-FU-based chemotherapies. An interim report showed that the maximum tolerated dose was 110 mg/m2 of oxaliplatin and 250 mg/m2 of irinotecan [141]. Meanwhile, in the 17 patients with colon cancers, mostly 5-FU refractory, evaluable for response, seven (41%) patients experienced partial responses [142]. There was no pharmacokinetic interaction between the two drugs [143]. These preliminary results suggest that this combination could be very attractive for future phase II trials in digestive malignancies. The same combination is being studied on a q two weeks schedule, and preliminary data have demonstrated the feasibility of fortnightly oxaliplatin at 85 mg/m2 and CPT-11 at 150 mg/m2 [142].

Conclusions In summary, oxaliplatin demonstrated preclinical activity in a broad spectrum of human tumors in vitro and in vivo. The activity of oxaliplatin was observed in a subset of primary cisplatin-resistant human tumors and partial or no cross-resistance with cisplatin was observed in several human cancer models selected for secondary resistance to cisplatin. Convergent evidence suggests that cancer cells with defects in mismatch repair may respond more favorably to oxaliplatin than to cisplatin or carboplatin. Despite a relatively protracted period of development, most clinical studies have focused on colorectal cancer, and the knowledge of oxaliplatin activity in other tumor types is, as yet, partial. While antitumoral activity can be obtained with oxaliplatin alone, the absence of hematologic toxicity makes oxaliplatin an attractive compound for combination with other anticancer drugs. The combination with 5-FU/folinic acid showed remarkable clinical activity in patients with advanced colorectal cancer who were both untreated and refractory to 5-FU/folinic acid combinations. The high response rates in patients with advanced colorectal cancer are buttressed by time-related parameters, time to progression, and overall survival. Finally, based on preclinical studies showing synergy between oxaliplatin and several new anticancer agents, clinical trials evaluating combinations may represent a further step towards improving the treatment of advanced colorectal cancers and other malignancies. Table 10 summarizes some of the ongoing clinical trials. The potential of oxaliplatin in the treatment of cancer is as yet to be fully explored, but available evidence would suggest that a new major anticancer agent will soon be available.

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Correspondence to: Prof. E. Cvitkovic Service des Maladies Sanguines Immunitaires et Tumorales Hopital Paul Brousse 14 Avenue Paul Vaillant Couturier 94000 Villejuif France