Pharmacokinetics of Intraarterial Mitomycin C in Humans1

[CANCER RESEARCH 43, 4474-4477, September 1983] Pharmacokinetics of Intraarterial Mitomycin C in Humans1

Edward Hu and Stephen B. Howell2

Department of Medicine, the General Clinical Research Center, and the Cancer Center, University of Southern California, San Diego, La Jolla, California 92093

ABSTRACT 1 - extraction ratio (B) The pharmacological advantage of mitomycin C (MMC) given 5-Fluoro-2'-deoxyuridine has a hepatic extraction of 94 to by intraarterial infusion as compared to i.v. infusion was studied in seven patients with cancer metastatic to the liver. Hepatic 99% (6), and thus from the point of view of the systemic artery, hepatic vein, and peripheral vein catheters were placed, circulation (fls) there is a strong pharmacological rationale for its and then each patient received constant infusions of MMC via infusion into the hepatic artery for the treatment of tumor masses the intraarterial and peripheral i.v. routes at 0.4,1.2, and 4.0 mg/ in the liver. On the other hand, the Rs values for 5-fluorouracil sq m/hr. MMC concentrations were measured in the hepatic (6), doxorubicin, bleomycin, and methotrexate are much lower artery, hepatic vein, and a peripheral vein by high-pressure liquid (1), and from the point of view of reducing overall toxicity, the chromatography after steady state had been reached at 2 hr. rationale for i.a. use of these agents is less well established. Mean plasma clearance increased significantly with infusion rate Several investigators have used i.a. MMC for the treatment of from 0.6 liter/min at 0.4 mg/sq m/hr to 1.1 liters/min at 4.0 mg/ hepatic tumors, and encouraging responses have been reported sq m/hr. The calculated relative advantage of treating hepatic (7,13-15). However, no pharmacokinetic data were obtained in tumors via the intraarterial route (R,) was found to be 2.5- to 3.6- these studies, and thus there is no way of estimating the mag fold at a plasma flow rate of 0.4 liter/sq m and MMC infusion nitude of R, and Rs for the i.a. use of MMC. We have used a rates of 0.4 to 4.0 mg/sq m/hr. The hepatic vein MMC concen recently developed high-pressure liquid Chromatographie tech tration averaged 30% higher during intraarterial than during i.v. nique for the quantitation of MMC in plasma to measure the infusion. Hepatic extraction of MMC averaged only 23%, so that systemic clearance and hepatic extraction ratio for MMC at the intraarterial route offered little advantage with respect to various infusion rates in 7 patients. reduced systemic toxicity. These data suggest a limited phar macological rationale for the selection of the intraarterial route MATERIALS AND METHODS for the treatment of hepatic tumors with MMC. Study Design. This studywas designedto compareMMC pharma- INTRODUCTION cokinetics during i.a. infusions into the hepatic artery, and during i.v. infusionsinto a peripheralvein in the same patient at various dose rates. There are 2 basic rationales for the selection of the i.a.3 route In each instance, MMC was infused at a constant rate until steady state rather than the i.v. route for administration of chemotherapeutic was achieved,and blood samples were obtained from the hepatic artery agents (1). The first is the possibility that the i.a. route can and vein, and from a peripheral vein (the hepatic artery was sampled only during i.v. infusions).All infusions were carried out using constant- produce a greater total tumor exposure to drug, and thus result infusion pumps. Following achievement of steady state at the starting in a higher response rate. The second is that if the drug is dose rate, the MMC infusion rate was escalated in steps from 0.4 to 1.2 extensively extracted and metabolized in the tumor or tumor- to 4.0 mg/sq m/hr; i.v. and i.a. studies were carried out sequentiallyover bearing organ, then the amount of drug reaching the systemic a 24- to 48-hr period. circulation may be less following i.a. than i.v. infusion. The relative Patients. Seven patientswith histologicallyprovenmetastaticcarci advantage of the i.a. route from the point of view of total drug noma in the liver gave their informed consent to enter this study. There exposure for the tumor (R,) is a function of the total body were 5 males and 2 females, and the median age was 61 years (range, clearance and tumor blood flow as indicated by Equation A (1). 51 to 86 years).Six patients had colon carcinomaand one had metastatic R, is greatest when tumor blood flow is low and when the melanoma. The entrance criteria for the study included a predicted systemic clearance of the drug is high. R, is not influenced by lifespan of >1 month; leukocyte count, >3,000/cu mm; platelet count, >100,000/cu mm; blood urea nitrogen, <40 mg/dl; creatinine, <2 mg/ the amount of drug extracted and metabolized in the tumor dl; the presenceof a tumor mass that could be infused via a singleartery; (extraction ratio) (4). The relative advantage of the i.a. route over and recovery from the toxicity associated with prior therapies. the i.v. route from the point of view of reducing systemic toxicity TreatmentPlan.Allpatientswerehospitalizedinthe ClinicalResearch (Rs) is, however, highly dependent on the extraction ratio, as Center at the University of California, San Diego Medical Center. indicated by Equation B. Hepatic artery and vein catheters were introduced through the femoral _ apparent total body clearance artery and vein by the Seldinger technique (18) and guided into position (A) using angiographiemonitoring. Both dynamic and static liver scans were tumor blood flow obtained using 4 mCi "Tc-labeled macroaggregated albumin at a flow

1This study was supported in part by Grant CA 23100 from the National Cancer rate of 30 ml/hr (9). Each patient was fully heparinized by continuous Institute, and by the University of California, San Diego, General Clinical Research infusion of 500 to 1000 units of heparin per hr. The requisite dose of Center Grant RR-00827 from the NIH Division of Research Resources. This work MMC was mixed in 0.9% NaCI solution, and infusions were performed was conducted in part by the Clayton Foundation for Research, California Division. at 0.4, 1.2, and 4.0 mg/sq m/hr at flow rates of 10, 30, and 100 ml/hr, 2 Clayton Foundation Investigator. To whom requests for reprints should be respectively. addressed, at Department of Medicine, Cancer Center (T-012), University of Cali fornia, San Diego, La Jolla, Calif. 92093. MMC Assay. MMC wasassayedinheparinizedplasmasamplesusing 3The abbreviations used are: i.a., intraarterial; MMC, mitomycin C. a modification of the technique reported by den Hartigh ef al. (3). Received December 27,1982; accepted June 6,1983. Crystalline sodium chloride was added to saturation (0.2 to 0.3 g), and

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Downloaded from cancerres.aacrjournals.org on September 26, 2021. © 1983 American Association for Cancer Research. Intraarterial Mitomycin C the plasma sample was mixed thoroughly for 1 min with 9 volumes of increased from 0.4 to 4.0 mg/sq m/hr. The increase was statis chlorofornrisopropyl alcohol (1:1) before being centrifugea at 990 x g tically significant (p < 0.05, t test) for both i.a. and i.v. infusions; for 10 min. The upper organic phase was transferred to a conical test the differences between the clearances associated with i.a. and tube and evaporated to dryness under nitrogen. The residue was recon stituted in 100 Â¿Â¿Iof100% methanol, and 20-/J aliquots were chromato- i.v. infusions were not significant. Using the mean of the clearance values for both the Â¡.a.and graphed using a Waters Associates (Milford, Mass.) instrument consist ing of a Model 6000 A pump, Model 71 OB sample processor, Model 730 i.v. route at each infusion rate, it was possible to calculate R, as data module, a Model 450 variable-wavelength detector, and an RCM a function of tumor plasma flow rate from Equation A, and the radial compression column (10 cm x 8.0 mm CÃeRadial-PAK cartridge, resulting family of curves for MMC infusion rates of 0.4 to 4.0 10-^m particle size). The mobile phase was 70% 20 UM potassium mg/sq m/min are presented in Chart 3. It can be seen that in the phosphate buffer (pH 6.0) and 30% methanol. Analysis was carried out case of MMC, R, values of greater than 3 could only be obtained isocractically at a flow rate of 1.5 ml/min, and the column effluent was with plasma flow rates of less than approximately 0.4 liter/min. monitored at 365 nm. The retention time of the MMC was 5.3 min, and However, with each incremental reduction in plasma flow rate there was base-line separation of the MMC peak from all other peaks in below this value, the value off?, increases more and more rapidly, the chromatogram. MMC concentration was calculated from integration and at a flow rate of 0.2 liter/min there is potentially a 6-fold of the area under the MMC peaks, and by comparison to external advantage to the i.a. over the i.v. route from the point of view of standards run on the pretreatment plasma from each patient. The limit of sensitivity of this assay was 1 ng/ml, and recovery was 76.7 Â±5.7% total drug exposure for the tumor. (S.D.), with a coefficient of variation of 2.5%. If one assumes that the tumor hepatic vein concentration is a minimal estimate of actual MMC concentration in the tumor bed, then it is possible to independently estimate the relative advan RESULTS tage of an i.a. over an i.v. infusion by comparing the steady-state Relative Advantage for the Tumor. Steady-state MMC pe hepatic vein MMC concentration during infusion via the 2 routes. ripheral and hepatic vein concentrations were reached within 2 Chart 4 shows the mean MMC concentrations in the hepatic hr of starting either an Â¡.a.or an i.v. MMC infusion, and the rate vein during i.a. and i.v. infusions as a function of MMC dose rate. of approach to steady state was not influenced by the MMC As was the case for the peripheral vein measurements, the infusion rate over the range of 0.4 to 4.0 mg/sq m/hr. Chart 1 hepatic vein MMC concentrations were linearly related to the shows the mean steady-state peripheral vein concentrations as infusion rate. The ratio of the slope of the i.a. curve to that of a function of infusion rate. The plasma concentration increased the i.v. curve was 1.3, indicating an advantage of approximately linearly with infusion rate, and was nearly the same for Â¡.a.and 30% for the i.a. route at each of the 3 infusion rates. Thus, for i.v. infusions performed at the same dose rate. The peripheral vein plasma concentration was approximately 6 times higher at an infusion rate of 4 mg/sq m/hr than at 0.4 mg/sq m/hr. From ÃŠ the data depicted in Chart 1, the plasma clearance of MMC can 5 IO be calculated as indicated by Equation C. Clearance= infusion rate steady-state plasma concentration (C)

Chart 2 shows plasma clearance as a function of infusion rate for both the i.a. and i.v. routes of administration. At an i.v. infusion rate of 0.4 mg/sq m/hr, the plasma clearance was 0.59 Â±0.15 (S.D.) liter/min; the clearance of 0.59 Â±0.34 liter/min O I 2 3 4 during i.a. infusion was not significantly different. Interestingly, MMC INFUSION RATE, for both routes, plasma clearance rose as the infusion rate was mg/sq m/hr Chart 2. Plasma clearance of MMC as a function of dose rate during i.a. (â€¢), and i.v. (O) infusions. Bars, S.E. z I50r

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o: LJ O- I 2345 0 0.2 0.4 0.6 0.8 I.O I.2 I.4 MMC INFUSION RATE, PLASMA TUMOR FLOW, liter/min mg/sq m/hr Chart 3. Calculated relative advantage of an i.a. infusion from the point of view Chart 1. Peripheral vein MMC concentration as a function of dose rate during of the tumor (R,) at MMC dose rates of 0.4 ( ), 1.2 ( ), and 4.0 ( ) i.a. (â€¢),andi.v. (O) infusions. Bars, S.D. mg/sq m/hr as a function of tumor plasma flow rates.

SEPTEMBER 1983 4475

few drugs with established activity against tumors that com monly metastasize to the liver (2). Several investigators have reported remarkable response rates with i.a. MMC (13, 15). However, there is little pharmacokinetic data to support the superiority of the Â¡.a.route for the use of this drug. In this study, MMC was infused at a variety of dose rates, and each patient received the drug by both the i.a. and i.v. routes, thus serving as his own control. Near steady-state plasma con centrations were reached by 2 hr during both i.a. and i.v. infu sions, consistent with the initial half-life of 10 to 17 min reported by other investigators following rapid i.v. infusion (2, 16, 17). This suggests that use of the i.a. route of administration did not change the initial distribution of the drug in the body. The clearance of MMC from the plasma compartment was also not different for i.a. versus i.v. infusions at any of the dose rates 12345 studied. However, by either the i.a. or i.v. route, the plasma MMC INFUSION RATE, mq/sq m/hr clearance of MMC did vary with infusion rate. Based on early studies, which depended on relatively insensitive assays for the Chart 4. Hepatic vein MMC concentration as a function of dose rate during i.a. (â€¢),andi.v. (O) infusions of MMC. Bars, S.D. quantitation of MMC, the statement has been made that the clearance of MMC changes with concentration, being lower at the tumors included in this study, the i.a. route of administration higher plasma MMC levels (8, 10,12). In contrast, using a much more sensitive assay for MMC, we found that there was a afforded only a relatively small advantage over the i.v. route, significant increase in clearance as the plasma concentration of when estimated by this technique. MMC was raised from 20 to 120 ng/ml. The basis of this increase Relative Advantage for the Systemic Circulation. The rela in clearance with concentration is unknown. It could be related tive advantage of an i.a. infusion from the point of view of reduction in systemic toxicity (Rs) is related to the amount of to changes in several parameters not quantitated in this study, such as plasma protein binding, renal clearance, or hepatic drug removed by the perfused organ before the blood reaches metabolism. Hepatic metabolism accounts for a large portion of the venous circulation (Equation B). Hepatic artery and hepatic plasma clearance (2), and the change in clearance may be due vein MMC concentrations were measured at steady state during to an increased rate of metabolism as the drug concentration i.v. MMC infusion, and the hepatic extraction ratio (ER) was approaches the Km of the enzyme system. However, if this was calculated according to Equation D. the case, the 2-fold enhancement of clearance was not accom hepatic artery - hepatic vein ER = (D) panied by a similar change in the hepatic extraction ratio (see hepatic artery below). The extraction ratios were 0.30 Â±0.12 (S.E.), 0.16 Â±0.01, and It is apparent from Equation A that for any given clearance 0.21 Â±0.08 for MMC infusion rates of 0.4, 1.2, and 4.0 mg/sq value, R, varies with tumor plasma flow. The data obtained from m/min, respectively. The variation with dose rate was not statis this study permitted calculation of the clearance of MMC at tically significant; however, the extraction ratio for all dose rates various dose rates, and thus allowed the construction of a family was 0.22 Â±0.05, and this was significantly different from zero of curves describing the expected R, value as a function of tumor (p > 0.05, Student's i test). The value of Rs for the 7 patients plasma flow (Chart 3). The graphic depiction of these curves included in this study was 1.39 Â±0.11 (S.E.). Thus, the i.a. route emphasizes the point that, although infusion rate did have some of administration of MMC for hepatic tumors resulted in a definite, impact on R, values, its effect was small in comparison to the but not very large, reduction in systemic exposure to the drug. effect of tumor plasma flow. The curves indicate that for organs The fact that the extraction ratio did not vary with infusion rate such as the liver and kidneys with relatively large arterial plasma indicates that even at 4.0 mg/sq m/hr, the i.a. clearance of MMC flows, the maximum expected value for R, would be quite low was not completely saturated. (4). The ratio of the hepatic vein MMC concentration during i.a. to that during i.v. infusion affords an independent estimate of R,, DISCUSSION and for the infusions performed in this study the mean value was The use of the i.a. route for administration of chemotherapeutic only 1.3. This represents a minimal estimate, since during pas agents has attracted attention for 2 major reasons. The first is sage from the tumor bed to the hepatic vein there is dilution due that the i.a. route may result in greater total drug exposure for to the admixing of portal blood during i.a. infusion. As a check tumor in the organ perfused, and the second is that drug extrac on this estimate of R,, Equation A can be solved for blood flow tion or metabolism in the organ may reduce the amount of the to the liver; R, of 1.3 would yield a hepatic blood flow of chemotherapeutic agent reaching the systemic circulation, and approximately 2 liters/sq m/min which is somewhat high, but an thereby reduce overall toxicity. In pharmacological terms, the R, of 1.6 would yield a blood flow of 1 liter/sq m/min, which is relative advantage of the i.a. route for a particular drug can be within the range previously reported (6). quantitated in terms of R, and Rs, as defined by Equations A and Both the calculated and measured estimates of R, for intrahe- B. We chose to investigate the pharmacokinetics of i.a. MMC patic arterial MMC infusions suggest that there is not a strong because MMC has a broad range of activity and is one of the pharmacological rationale for selection of the i.a. over the i.v.

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route for the treatment of resistant tumors in this or other organs for this study, Dr. Joseph Bookstein for the catheterizations, and Sharon Don for with high plasma flow rates. The ft, curves suggest that the high preparation of the manuscript. dose rate of MMC infusion was slightly more favorable than the REFERENCES low dose rate, and that i.a. treatment with MMC should be very much more effective for tumors resident in organs with plasma 1. Chen, H-S. G., and Gross, J. F. Intra-arterial infusion of anticancer drugs: theoretic aspects of drug delivery and review of responses. Cancer Treat. flows of less than 0.3 liter/min. The relationship between plasma Rep., 64: 31-40,1980. flow rate and ft, suggests that the i.a. route for the delivery of 2. Crooke, S. T., and Bradner, W. T. Mitomycin C: a review. Cancer Treat. Rev., MMC may be most useful when combined with a technique to 3: 121-139. 1976. 3. den Hartigh, J., van Dort, W. J., McVie, G.. Bocken, M. C. Y. M., and Pinedo, simultaneously diminish plasma flow. H. M. A sensitive method for analysis of mitomycin C (MMC) in clinical The relative advantage of the i.a. over the i.v. route from the pharmacology studies. Proc. Am. Assoc. Cancer Res., 22:179,1981. 4. Eckman, W. W., Patlak, C. S., and Fenstermacher,J. D. A critical evaluation point of view of reducing systemic toxicity (fls) is a function of of the principles governing the advantages of intra-arterial infusions. J. Phar- how much of the drug administered into the tumor-bearing organ macokinet. Biopharm., 2. 257-285, 1974. fails to reach the vein draining the tumor and enters the systemic 5. Ensminger, W. D., Dakhil, S., and Cho, K. Improved regional selectivity of hepatic arterial bischloroethylnitrosoureaplus degradablestarch microspheres. circulation. As indicated in Equation B, Rs is directly related to Clin. Res., 28. 742, 1980. the extraction ratio; the greater the extraction ratio, the greater 6. Ensminger, W. D., Rosowsky, A., Raso, V., Levin, D., Glode, M., Come, S., Steele, G., and Frei, E., III. A clinical-pharmacologicalevaluation of hepatic the value of fts. In this study, the extraction ratio for MMC was arterial infusions of 5-fluorc-2'-deoxyuridine and 5-fluorouracil. Cancer Res., found to average only 22%, resulting in an fts value of only 1.39. 38:3784-3792,1978. Although, since the liver plays an important part in the metabo 7. Fortuny, I. E., Theologides, A., and Kennedy, B. J. Hepatic arterial infusion for liver mÃ©tastasesfromcolon cancer: comparison of mitomycin C (NCS-26980) lism of MMC, one might expect a variation in extraction ratio and 5-fluorouracil(MSC-19893).Cancer Chemother. Rep. Part I, 59: 401-404, with changes in infusion rate due to saturation of enzymatic 1975. 8. Fujita, H. Comparative study on the blood level, tissue distribution, excretion processes, this was not observed over the range of dose rates and inactivation of anticancer drugs. Jpn. J. Clin. Oncol.. 1: 151-162, 1971. used in this study. We conclude from these data that i.a. therapy 9. Kaplan, W. D., Ensminger, W. D., Come, S. E., Smith, E. M., D'Orsi, C. J., via the hepatic artery cannot be counted on to significantly Levin, D. C., Takvorian. R. W., and Steele.G. D.. Jr. Radionuclideangiography to predict patient responses to hepatic artery chemotherapy. Cancer Treat. reduce systemic toxicity due to MMC. Rep., 64: 1217-1222,1980. Although the data from this study indicate that there is only a 10. Kawazu, M. Studies on the chemotherapyof cancer by regionalperfusion with limited pharmacokinetic rationale for the selection of the i.a. over specific reference to blood levels of chemotherapeutic agent. J. Kumamoto Med. See., 45: 391-413, 1971. the i.v. route for the treatment of intrahepatic tumors, MMC 11. Kennedy, K. A.. Rockwell, S., and Sartorelli, A. C. Preferential activation of remains one of the most interesting candidates for future studies mitomycin C to cytotoxic metabolites by hypoxic tumor cells. Cancer Res., 40: of i.a. therapy. MMC is activated in areas of low oxidation- 2356-2360, 1980. 12. Kimura, K., et al. On studies of cancer chemotherapy (IV). With special reduction potential, and the presence of oxygen significantly reference to clinical effects and blood level of mitomycin C. Jpn. J. Med., 4: slows its activation to a cytotoxic form (11). Recently, the i.a. 145-146,1965. 13. Mattsson, W., Jonsson, K., Heltekatt, C., and Hallsten, L. Short-term intra- injection of starch microspheres (Spherex; Pharmacia, Inc.) that arterial mitomycin C in hepatic mÃ©tastases.ActaRadiol.Ther. Phys. Biol., 79: can be degraded by serum amylase has been used to markedly 321-325, 1980. reduce tumor plasma flow rates for periods of up to approxi 14. Patt, Y. Z., Chuang, V. P., Wallace, S., and Mavligit, G. M. Hepatic arterial infusion (HAI)of floxuridine, Adriamycin and mitomycin C (FAM) for hepatoma mately 30 min (5). Since interruption of blood flow simultaneously confined to the liver. Proc. Am. Assoc. Cancer Res., 22: 450, 1981. enhances ft, and creates a microenvironment favoring the acti 15. Patt, Y. Z., Wallace. S., Freireich, E. J, Chuang, V. P., Hersh, E. M., and Mavligit, G. M. The palliative role of hepatic arterial infusion and arterial vation of MMC, the combined injection of both agents via the Â¡.a. occlusion in colorectal carcinoma metastatic to the liver. Lancet, 7: 349-351, route may be very much more effective than the use of i.a. MCC 1981. alone. A cooperative study of such a program is currently under 16. Reich, S. D. Clinical pharmacology of mitomycin C. In: S. K. Carter and S. T. Crooke (eds.), Mitomycin C Current Status and New Developments,pp. 243- way. 250. New York: Academic Press, Inc., 1979. 17. Sama, G. P., Champlin, R., Wells, J., and Gale, R. P. Phase I study of high- dose mitomycin with autologous bone marrow support. Cancer Treat. Rep., ACKNOWLEDGMENTS 66. 277-282, 1982. 18. Seldinger, S. I. Catheter replacement of the needle in percutaneous arteriog- The authors would like to thank Dr. Thomas N. Campbellfor referral of patients raphy: a new technique. Acta Radiol. (Stockh.), 39: 368-376,1953.

SEPTEMBER 1983 4477

Edward Hu and Stephen B. Howell

Cancer Res 1983;43:4474-4477.

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