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Clinical Trials |
Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215 [M. B. A., J. M., J. G.]; University of Michigan Medical Center, Ann Arbor, Michigan 48109 [B. R.]; University of Southern California/Norris Comprehensive Cancer Center, Los Angeles, California 90033 [J. W.]; University of Illinois Medical Center, Chicago, Illinois 60612 [J. S.]; and Cytokine PharmaSciences, Inc., West Conshohocken, Pennsylvania 19428 [B. L. M., T. P.]
| ABSTRACT |
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25 mg/m2 seemed to exacerbate IL-2-induced nephrotoxicity: grade 3 or 4 creatinine increases developed in 3 of 6 patients at 25 or 32 mg/m2, as compared with 1 of 16 patients at doses
16 mg/m2. The MTD for CNI-1493 given with high-dose IL-2 was 16 mg/m2. The dose-limiting toxicity of IL-2 was hypotension in 63% of patients; overall tolerance to IL-2 was not improved by CNI-1493. However, relative to changes seen in a reference group receiving high-dose IL-2 alone, at doses
4 mg/m2 CNI-1493 did show evidence of pharmacological activity as an inhibitor of tumor necrosis factor production. | INTRODUCTION |
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, have been used and give similar overall response rates (5, 6, 7)
. However, the proportion of patients with complete responses does not seem to be as high nor are the responses as durable with lower-dose as with high-dose IL-2 (8)
.
IL-2 induces production of several proinflammatory cytokines such as IL-1, tumor necrosis factor (TNF-
), and IFN-
. These and other substances (9, 10, 11, 12, 13)
, including nitric oxide (14
, 15)
, are thought to be involved in the toxicity of IL-2.
CNI-1493 is a tetravalent guanylhydrazone, N,N'-bis[3,5-bis[1(aminoiminomethyl)hydrazonoethyl]phenyl]decanediamide tetrahydrochloride. It suppresses LPS-induced nitric oxide production as well as production of several proinflammatory cytokines, including TNF-
, IL-1, IL-6, and macrophage inflammatory proteins 1
and 1ß, from human peripheral blood mononuclear cells (16)
. CNI-1493 has been shown to be protective in preclinical models of endotoxic shock, sepsis, pancreatitis (17)
, experimental allergic encephalomyelitis (18)
, stroke (19)
, and rheumatoid arthritis4
.
A protective effect of CNI-1493 was demonstrated in rats given high doses of IL-2 (20)
. In Sprague Dawley rats, IL-2 given by continuous infusion at a dose
6 x 106 IU/m2 daily for up to 14 days was uniformly fatal. Rats receiving 110 mg/kg CNI-1493 i.p. once daily were protected against toxicity of IL-2 administered at doses up to 30 x 106 IU/m2 daily. At a dose of 6 x 106 IU/m2 daily by continuous hepatic artery infusion, IL-2 is not very effective against Novikoff hepatoma. By administering CNI-1493, the dose of IL-2 could be increased to 30 x 106 IU/m2 daily. At that dose, in a group of 10 animals with established tumors, 5 had a reduction of the tumor mass to <1 mm3 and 5 had complete regression of their tumors. Tumors continued to grow in all untreated control animals.
On the basis of these findings in a rodent model, we conducted a Phase I study of CNI-1493 given alone and in combination with high-dose IL-2 in patients with renal cancer and melanoma. The primary objective of the study was to determine the MTD and side effect profile of CNI-1493 alone and in combination with high-dose IL-2. Secondary objectives were to examine the effect of CNI-1493 on IL-2 toxicity, the biological parameters known to be affected by IL-2, and number of doses of IL-2 administered; determination of the pharmacokinetic profile of CNI-1493 alone and in combination with IL-2; and to assess tumor responses in patients treated with the combination of CNI-1493 and high-dose IL-2.
| MATERIALS AND METHODS |
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1.5 mg/dl or creatinine clearance >60 ml/min. At least 4 weeks were to have elapsed from the end of previous therapy (6 weeks for nitrosoureas or mitomycin), and concurrent therapy was not permitted. No more than one prior biological response modifier treatment regimen for metastatic disease was permitted. If the patient had previously received IL-2, at least 6 months were to have elapsed since that therapy. The study was approved by the institutional review board at each participating institution. All patients gave signed informed consent.
Treatment.
Patients received treatment according to the schema in Fig. 1
. CNI-1493 was diluted in 100 ml 5% dextrose and administered i.v. once daily over 30 min. The drug was first administered alone daily for 5 days. After a 9-day rest period, CNI-1493 was administered again once daily in conjunction with high-dose IL-2 in two 5-day courses separated by a 9-day rest period, days 15 and 1519. IL-2 was administered at the standard recommended dose and schedule, 600,000 IU/kg/dose every 8 h for up to 14 doses/course. Individual IL-2 doses could be held for toxicity, but there were no IL-2 dose modifications. CNI-1493 was discontinued after a decision that no further IL-2 would be administered during a course of therapy.
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During high-dose IL-2 treatment, patients received standard prophylaxis for IL-2-induced toxicity, including acetaminophen, indomethacin, and either cimetidine or ranitidine. Patients with indwelling catheters received oral ciprofloxacin or cephalexin. Patients received other supportive care for IL-2 toxicity as appropriate (21) .
Parameters Evaluated.
The primary objective of the study was determination of the MTD of CNI-1493 either alone or in conjunction with high-dose IL-2. The MTD was defined as the dose below that at which at least two patients experienced a DLT. DLT was defined as any adverse event falling into a category in Table 1
and which was: (a) felt to be possibly or probably related to CNI-1493; and (b) not ameliorated by symptomatic measures.
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Secondary end points were evidence of amelioration of IL-2 toxicity by CNI-1493 and an increase in the number of IL-2 doses administered relative to historical controls.
Patients underwent physical examination and hematological and biochemical testing before and periodically during treatment. No statistical comparisons of clinical laboratory parameters were planned for this study. However, on review of the adverse events observed during combined therapy with CNI-1493 and IL-2, it was noted that there was less liver toxicity than anticipated for high-dose IL-2 alone. Therefore, post hoc analyses were performed to examine changes in bilirubin and liver enzymes as a function of dose. Regression analyses (22) were performed using results of each dose-group independently to look at the significance of these changes from day 1, just before the start of IL-2, through day 6, the day after IL-2 treatment was scheduled to stop. Included in these analyses as a reference group were 10 patients fulfilling the same entry criteria as study patients, but who were receiving high-dose IL-2 alone at one of the investigative sites.
For most patients treated with
4 mg/m2 CNI-1493, TNF levels were measured at baseline and periodically through 24 h after the initial dose of combined therapy. TNF levels through 8 h after IL-2 administration in a reference group (three patients) treated with high-dose IL-2 only at one of the participating institutions were used for comparison. Serum specimens for TNF levels and pharmacological determinations were frozen at -20°C until analysis. TNF levels were measured using a commercially available ELISA kit (Endogen, Woburn, MA).
Pharmacokinetic sampling for CNI-1493 and IL-2 levels was performed on selected patients. A high pressure liquid chromatography assay was developed for CNI-1493 in biological fluids and performed by Microconstants, Inc., San Diego, CA5 . Plasma samples containing EDTA as the anticoagulant were extracted by protein precipitation with acetonitrile. The extract was analyzed by direct injection. The mobile phase was nebulized using heated nitrogen in a Z-spray source/interface, and the ionized compounds were detected using a triple quadrupole mass spectrometer. Assays for IL-2 were performed on selected patients using a commercial ELISA method (Quantikine Human IL-2 immunoassay kit, R&D Systems, Minneapolis, MN) by Performance Bioanalytical, Inc., San Diego, CA. Descriptive pharmacokinetic parameters were determined by standard model independent methods (23) based on each of the individual sets of plasma concentration-time data.
Repeat tumor assessment was conducted at least once after treatment was completed. Patients with stable disease or better were eligible for retreatment with combined CNI-1493 and IL-2 at 1214 week intervals.
| RESULTS |
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Patients were typical of those receiving high dose IL-2 at the participating institutions. Patient characteristics are shown in Table 2
by low (2 or 4 mg/m2; n = 10), intermediate (8 or 16 mg/m2; n = 7), and high (25 or 32 mg/m2; n = 7) dose groups, as well as all patients together. Patient characteristics were similar among dose groups.
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Treatment Administered.
Table 3
shows CNI-1493 and IL-2 dosing by cohort. All but one patient received all five doses of CNI-1493 administered alone. That one patient, enrolled in the 4-mg/m2 cohort, opted to discontinue study participation after receiving four doses of CNI-1493.
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Most patients received the full five doses of CNI-1493 when administered with each course of IL-2, as shown in Table 3
. One patient, who received 32 mg/m2, received five doses of CNI-1493 alone but was taken off study before receiving IL-2, as two patients had already experienced DLT with the combination of IL-2 and CNI-1493 at that dose level.
Forty courses of IL-2 were administered. One patient, who received 16 mg/m2 of CNI-1493, received the full 28 doses of IL-2. One patient each treated at 2, 8, and 16 mg/m2 received 14 doses of IL-2 during one of the two courses of that drug. In all cases, the reasons for discontinuing or withholding IL-2 were established toxicities of that drug. In 22 of 35 courses (63%) in which IL-2 was discontinued at <14 doses, the reason for discontinuation was refractory hypotension, either alone or along with other toxicities.
As can be seen from Table 3
, CNI-1493 did not seem to increase the number of doses of IL-2 that could be administered. At doses between 2 and 16 mg/m2, there is no suggestion that the number of IL-2 doses administered increased with escalation of CNI-1493, although the number of patients in each dose group is too small to demonstrate anything but a very marked effect. At 25 and 32 mg/m2 CNI-1493, toxicity of the combination supervened, and the number of IL-2 doses administered per course decreased.
There was no trend toward a decreasing incidence or severity of cardiovascular toxicity (mainly hypotension) as the dose of CNI-1493 was increased, nor was the frequency of discontinuation of therapy attributable to cardiovascular toxicity decreased as the dose of CNI-1493 was increased.
Toxicity of CNI-1493.
CNI-1493 was well tolerated when given as a single agent daily for five days. Injection site reactions in two patients were the only clinical adverse events attributed to study medication. One patient treated at 4 mg/m2 developed moderate and one treated at 32 mg/m2 developed mild treatment-related phlebitis at the injection site, the former on the fifth day of CNI-1493 treatment and the latter on the second day of treatment. In both patients, the phlebitis resolved without sequelae.
Five patients had by National Cancer Institute Common Toxicity Criteria grade 1 increases in serum creatinine while on CNI-1493 alone: one of seven treated at 4 mg/m2, one of one treated at 25 mg/m2, and three of six treated at 32 mg/m2. The increases in three of these patients were only 0.10.3 mg/dl. The patient treated with 25 mg/m2 had an increase from 0.9 mg/dl at baseline to 1.6 mg/dl just before starting combination therapy; one patient treated with 32 mg/m2 had an increase from 1.2 mg/dl at baseline to 1.7 mg/dl just before starting IL-2. While on CNI-1493 alone, patients experienced a variety of other adverse events that were felt by the investigators to be related to the patients underlying malignancies or to intercurrent illnesses.
During treatment with the combination of CNI-1493 and IL-2, patients experienced the spectrum of side effects typically attributed to high-dose IL-2 (24)
. Except as noted below with regard to MTD and pharmacological effects, there was no correlation between incidence or severity of toxicities and dose of CNI-1493.When 32 mg/m2 CNI-1493 was given along with IL-2, two patients developed markedly increased creatinine levels, to 8.0 and 5.7 mg/dl after only eight and five doses of IL-2, respectively. Both of these patients had metastatic melanoma, and neither had evidence of preexisting renal disease nor had they received cisplatin. One patient required transient hemodialysis. In both instances, the creatinine returned to normal (
1.3 mg/dl) within 6 weeks of discontinuation of CNI-1493 and IL-2. One patient was treated at an intermediate dose level, 25 mg/m2, but that patients creatinine increased to 3.0 mg/dl after five doses of IL-2 during the first treatment course, and therapy was discontinued. No additional patients were treated at 25 mg/m2. The MTD of CNI-1493 given in combination with high dose IL-2 was, therefore, determined to be 16 mg/m2. The MTD for CNI-1493 alone is >32 mg/m2.
Effect of CNI-1493 on TNF Levels and Hepatic Function Changes.
The increase in serum TNF levels associated with IL-2 administration was attenuated in patients receiving CNI-1493, as shown in Fig. 2
. For clarity purposes, data are displayed by low (4 mg/m2), intermediate (8 or 16 mg/m2), and high (32 mg/m2; TNF data were not obtained on the patient treated with 25 mg/m2) doses of CNI-1493. As can be seen in the figure, by 4 h after IL-2 dosing, the TNF increase was blocked in a dose-dependent manner. At 8 h after dosing, mean ± SD values were 5.75 ± 5.44 pg/ml for the 4-mg/m2 group, 0.83 ± 1.33 pg/ml for the 8- or 16-mg/m2 group, and 0.20 ± 0.40 for the 32-mg/m2 group; the mean value was 26.67 ± 4.16 pg/ml in the reference group. Median values were similar. TNF levels remained low throughout IL-2 dosing in patients receiving CNI-1493.
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As shown in Fig. 4
, peak ALT levels were lower in patients receiving CNI-1493 than in the reference group; there seemed to be a plateau at 8 or 16 mg/m2. At day 6, the median increase in ALT in the reference group was 67 units/liter. Median changes in the low-, medium-, and high-dose groups were 93%, 46%, and 74% of that for the control group. Changes in AST paralleled those in ALT (data not shown).
By regression analysis, the P for the relationship between CNI-1493 dose and the change in total bilirubin was 0.013, that for the relationship between CNI-1493 dose and ALT change was 0.068, and for AST change, 0.063. Ps for these comparisons, excluding the reference group, were similar, inasmuch as 2 mg/m2 CNI-1493 was essentially a no-effect dose. Taken together, these biochemical data suggest that CNI-1493 may ameliorate hepatocellular toxicity induced by high-dose IL-2.
Tumor Response.
Serial tumor response assessments were obtained on all but four patients in the study. One patient with renal cancer (4 mg/m2) had a confirmed complete response that was ongoing at the 12 month follow-up. None of the 11 other patients with renal cell carcinoma or the 8 patients with melanoma had a major response to therapy. Four renal cancer and three melanoma patients had stable disease for at least 12 weeks.
Pharmacokinetics.
Pharmacokinetic data on CNI-1493 were obtained from nine patients (three at 4-, two at 16-, one at 25-, and three at 32-mg/m2 doses of CNI-1493) and on IL-2 from six patients (one each at 2 and 4-, and two each at 8- and 16-mg/m2 doses of CNI-1493).
The half-life for IL-2 was 1.17 ± 0.33 h after the first dose of IL-2 and 1.20 ± 0.45 h after dosing on day 4. There was no change in t1/2 as a function of CNI-1493 dose.
The half-life of CNI-1493 on days 1 and 5 of treatment without IL-2 was 1.42 ± 0.67 and 1.02 ± 0.35 h, respectively. On the first and third or fourth days of combined therapy with IL-2, t1/2 of CNI-1493 was 1.43 ± 0.40 and 0.83 ± 0.17 h, respectively. There was no indication of variation in t1/2 with increasing dose of CNI-1493.
Cmax and area under the curve increased with increasing dose of CNI-1493. On day 1 of treatment, at 32 mg/m2, Cmax was 6.2 ± 0.8 µg/ml and area under the curve was 432 ± 14 µg min/ml; on day 5, they were 3.8 ± 2.5 µg/ml and 246 ± 49 µg-min/ml, respectively. For all dose groups, there was no significant difference between day 1 and day 5 CNI-1493 pharmacokinetics, nor was there any difference in pharmacokinetics when CNI-1493 was given with IL-2 as compared with administration alone.
| DISCUSSION |
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As a single agent given daily for 5 days, CNI-1493 was well tolerated; the MTD was not reached at the highest dose administered in this study, 32 mg/m2. Higher doses were not tested as a single agent because it was considered inappropriate to treat the study population, patients with unresectable melanoma or renal cancer, with CNI-1493 alone if the drug were not to be used subsequently in combination with high-dose IL-2. The only toxicities attributed to CNI-1493 alone were occasional injection site phlebitis and grade 1 elevations of serum creatinine. In animal studies, injection-site phlebitis was very common and occasionally marked6 . In this study, CNI-1493 was given in dilute solution over 0.5 h to avoid contact with a high concentration of drug. This appeared to minimize the problem.
Serum creatinine increased
0.5 mg/dl from baseline to just before starting combination therapy with IL-2 in two patients; one of the patients was treated at 25 mg/m2 and one was treated at 32 mg/m2. During combination therapy with 25 or 32 mg/m2 of CNI-1493, nephrotoxicity greater than that expected from IL-2 alone was noted three of six patients. Clinically, reversible nephrotoxicity was the dose-limiting side effect of the combination.
In rat and dog toxicology studies of CNI-1493 alone, there was no biochemical evidence of nephrotoxicity. However, histological abnormalities were noted in rats treated at the highest dose used, 20 mg/kg (equivalent to 120 mg/m2) daily for 14 days. Two types of lesions were noted. The more common was multifocal degeneration and/or regeneration of the tubular epithelium; this was more pronounced in males. The changes were usually seen near the corticomedullary junction and were characterized by small groups of basophilic tubules lined with attenuated epithelium and sometimes with necrotic tubular cells. Minimal interstitial response, consisting of fibrosis and occasional mononuclear inflammatory cells, was also noted around some tubules.
High-dose IL-2 alone causes considerable nephrotoxicity. Increased creatinine is a common adverse event associated with IL-2 administration; creatinine >2.5 mg/dl is reported in 33% of patients receiving high-dose IL-2 (25) . Renal dysfunction occurs during high-dose IL-2 administration in association with capillary leak syndrome and prerenal azotemia; it resolves rapidly upon discontinuation of IL-2. Increases in serum creatinine after discontinuation of IL-2 are generally not seen.
A class of anti-inflammatory drugs very different from CNI-1493, NSAIDs are known to cause nephrotoxicity; all patients in this study received NSAIDs as prophylaxis against IL-2 toxicity. The mechanism of NSAID-induced nephrotoxicity is presumed to be the blocking of renal prostaglandin production (26, 27, 28) . Patients with underlying cardiovascular abnormalities appear to be more sensitive to the nephrotoxic effect of NSAIDs than individuals with normal cardiovascular systems. The nature of the mechanism of nephrotoxicity in patients receiving high-dose IL-2 and CNI-1493 remains to be determined. It may be that circulatory and renal compromise, which occurs during high-dose IL-2 therapy, and/or interaction with NSAIDs may predispose to nephrotoxicity in patients concomitantly receiving CNI-1493.
IL-2 induces the release of several proinflammatory cytokines, which have their own toxicities (8 , 9 , 11, 12, 13) . Patients receiving the higher doses of CNI-1493 had lower mean and median TNF levels than those receiving the lowest doses. When compared with reference patients treated with high-dose IL-2 alone, TNF levels were suppressed by >90% by either 8 or 16 mg/m2 of CNI-1493. Furthermore, although the t1/2 of CNI-1493 is only slightly more than 1 h, TNF levels remained suppressed after IL-2 doses administered 8 and 16 h later, suggesting that CNI-1493 exerts a pharmacological effect even when it is no longer detectable in the plasma.
CNI-1493 also appeared to exert a dose-dependent protective effect against IL-2-induced hepatocellular toxicity. There was a decrease in peak total bilirubin levels during the first course of combined CNI-1493 and IL-2. Patients who received 8 or 16 mg/m2 CNI-1493 had lower peak ALT levels than patients receiving 2 or 4 mg/m2; AST changes followed a similar pattern. No such pattern was seen with alkaline phosphatase changes. These observations suggest a protective effect on liver parenchymal cells, an effect also seen in the rat (20) .
The total number of doses of IL-2 administered was not increased by coadministration of CNI-1493. The compound did not appear to inhibit the cardiovascular effects of IL-2, especially the development of hypotension. This is the same situation observed in studies of soluble TNF receptor (29) , a compound that has now been demonstrated to have substantial therapeutic efficacy in patients with illnesses related to TNF excess (30 , 31) . Thus, it appears that inhibition of TNF activity, although effective in certain clinical situations, does not protect against dose-limiting IL-2 toxicity.
In summary, we have demonstrated that CNI-1493, a synthetic guanylhydrazone compound, can inhibit TNF release at well-tolerated doses. In addition, although the compound did not appear to improve overall tolerance to high-dose IL-2, it did seem to ameliorate IL-2-induced hepatotoxicity. Additional studies will be undertaken to elucidate the role of CNI-1493 in illnesses associated with proinflammatory cytokine excess.
| FOOTNOTES |
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1 Supported by Cytokine PharmaSciences, Inc., West Conshohocken, PA. Dr. T. Plasse and B. MacPherson are employees of Cytokine PharmaSciences, Inc. ![]()
2 To whom requests for reprints should be addressed, at Cytokine PharmaSciences, Inc., 150 South Warner Road, Suite 420, King of Prussia, PA 19406. Phone: (610) 687-0260; Fax: (610) 687-4340; E-mail: tplasse{at}plasse.tiac.net ![]()
3 The abbreviations used are: IL, interleukin; TNF, tumor necrosis factor; ALT, alanine aminotransferase; AST, aspartate aminotransferase; DLT, dose-limiting toxicity; MTD, maximum tolerated dose; NSAID, non-steroidal anti-inflammatory drugs. ![]()
4 Data on file, Cytokine PharmaSciences, Inc. ![]()
5 Lam G. MicroConstants Report MN99014: Method for the Determination of CNI-1493 in Human Plasma Using High Performance Liquid Chromatography with Mass Spectrometric (MS/MS) Detection, MicroConstants, San Diego, 1999. ![]()
6 Data on file, Cytokine PharmaSciences, Inc. ![]()
Received 9/ 5/00; revised 12/18/00; accepted 12/26/00.
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