Phase I Evaluation and Pharmacokinetics of Tiazofurin (2-ÃŸ-O- Ribofuranosylthiazole-4-Carboxamide, NSC 286193)1

[CANCER RESEARCH 45, 2859-2865, June 1985]

Phase I Evaluation and Pharmacokinetics of Tiazofurin (2-ÃŸ-o- Ribofuranosylthiazole-4-carboxamide, NSC 286193)1

Teresa J. Melink, Daniel D. Von Hoff,2 John G. KÃ¼hn,MarlaR. Hersh, Lawrence A. Sternson, Thomas F. Patton, Robert Siegler, David H. Boldt, and Gary M. Clark

Department of Medicine, Division of Oncology-Hematology, University of Texas Health Science Center at San Antonio and Audie Murphy Veterans Administration Hospital, San Antonio, Texas 78284 [T. J. M., D. D. V. H., J. G. K., M. R. H., D. H. B., G. M. C.], and Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66045 [L. A. S., T. F. P., R. S.]

ABSTRACT been studied both in vitro and in vivo utilizing murine tumor cells (4, 5, 7, 8, 15). It has been reported that this nucleoside is Tiazofurin (2-/3-D-ribofuranosylthiazole-4-carboxamide, TCAR, anabolized to an analogue of NAD whereby thiazole-4-carbox- Riboxamide, NSC 286193) is a novel C-nucleoside with antitumor amide replaces nicotinamide. This anabolite, termed thiazole-4- activity against several murine tumor models, including Lewis carboxamide adenine dinucleotide, is responsible for a potent lung carcinoma. The mechanism whereby this compound exerts inhibition of inosine-5'-monophosphate dehydrogenase with a its antineoplastic effects is most likely related to a state of consequent depression of guanosine nucleotide biosynthesis guanine nucleotide depletion whereby the anabolite, thiazole-4- carboxamide adenine dinucleotide, potently inhibits inosine-5'- and a cessation of tumor cell proliferation. Tiazofurin was selected for clinical trial because preclinical monophosphate dehydrogenase. This Phase I study was de testing demonstrated notable antitumor activity in several murine signed to determine the maximally tolerated dose of Tiazofurin tumor systems including the L1210 and P388 leukemias and administered on a 5-day, every-28-day schedule. Tiazofurin lev Lewis lung carcinoma (14). Tiazofurin caused significant in els were measured using a high-pressure liquid chromatography creases in life span in mice bearing these tumors. Antitumor assay, and pharmacokinetic studies were performed in patients activity in the animal models was schedule dependent in favor treated at each dose level. Nineteen patients received a total of of the daily, multiple-dose schedule. Recent data also indicate 24 courses of the drug in doses ranging from 550 to 2200 mg/ Tiazofurin has some antitumor activity against specific tumor sq m. The dose-limiting toxicities were pleuropericarditis and a types in a human tumor-cloning system (9). general illness best described as a "viral-like" syndrome (mani Animal toxicology studies conducted in CD2F! mice and bea fested by severe malaise, headaches, myalgias, fever, nausea, gle dogs3 showed the mice to be the more sensitive species. vomiting, and diarrhea). Other toxicity included myelosuppres- The toxic effects of Tiazofurin were predominantly nonhemato- sion, hyperuricemia, elevated serum creatine phosphokinase and logical, including a profound lethargy and prostration. Other serum glutamic oxaloacetic transaminase, conjunctivitis, mucos- toxicity included emesis, diarrhea, anorexia, weight loss, con itis, and desquamation of the palms of the hands. Plasma clear junctivitis, corneal edema, fever, and labored breathing. Effects ance of Tiazofurin followed a biexponential pattern with a har on the hematopoietic system were dose related and reversible, monic mean terminal half-life of 7.6 h. The mean volume of including anemia, thrombocytopenia, and leukopenia. The 10% distribution at steady state was 30 liters/sq m, and the mean lethal dose in mice was 5489.7 mg/sq m on the 5-day schedule. plasma clearance was 3 liters/h/sq m. The total cumulative One-tenth of the 10% lethal dose in mice was chosen as the urinary excretion ranged from 15 to 49%. The maximally toler starting dose for the Phase I clinical trial in humans. A multiple ated dose of Tiazofurin on a 5-day schedule was 1650 mg/sq daily dose schedule was chosen, since repetitive doses of Tia m. The recommended dose for Phase II evaluations is 1100 mg/ zofurin were most effective in animal systems. Additionally, sq m for 5 days. However, exploration of other schedules which pharmacokinetic and lymphocyte studies were performed in might allow administration of more Tiazofurin combined with patients treated at each dose level. biochemical studies including thiazole-4-carboxamide adenine dinucleotide measurements would be desirable. MATERIALS AND METHODS

INTRODUCTION Patient Selection. Patients with histologicallydocumented, advanced, Tiazofurin or 2-|8-D-ribofuranosylthiazole-4-carboxamide solid tumors who were refractory to all forms of known effective therapy were candidates for this study. Other eligibility criteria included a per (TCAR, Riboxamide, NSC 286193) is a novel synthetic C-nucleo formance status (Southwest Oncology Group) of 3 or less, life expect side structurally related to the potent antiviral agent Ribavirin ancy of at least 12 weeks, and adequate organ function as defined by: (16) (Chart 1). While initial research efforts with this compound bone marrow (WBC > 4000/cu mm, platelets > 100,000/cu mm, hemo were targeted for the search of new antiviral agents, Tiazofurin globin > 10 g/100 ml); liver (bilirubin < 2.0 mg/100 ml, SGOT4 < 1.5 later proved to be a more interesting and potentially useful times normal); and kidneys (blood urea nitrogen < 25 mg/100 ml and antitumor agent (14). The mechanism of action of Tiazofurin has creatinine < 2.0 mg/100 ml). Written informed consent was obtained from all patients according to institutional and federal guidelines. 1This study was supported by Contract NCI N01-CM-27542 and by NIH Grant RR-01346. 3 Phase II report of preclinical i.v. lethality and toxicity studies in CD2F, mice 2To whom requests for reprints should be addressed, at University of Texas and toxicity studies in beagle dogs administered Tiazofurin (NSC 286193). Battelle Health Science Center at San Antonio, Department of Medicine, Division of Oncol Columbus Toxicology Program, March 1983. ogy, 7703 Floyd Curl Drive, San Antonio, TX 78284. 4 The abbreviations used are: SGOT, serum glutamic oxaloacetic transaminase; Received 6/18/84; revised 2/25/85; accepted 3/5/85. CPK, creatine phosphokinase; CSF, cerebral spinal fluid.

plasma samples were separated by cold centrifugation and flash frozen in an acetone-dry ice bath. Aliquoted urine samples were collected at H2N-C 24-h intervals for 5 days. Plasma, tissue, and urine samples were kept frozen at -20Â°C and shipped on dry ice to the Department of Pharma ceutical Chemistry at the University of Kansas for analysis. Tissue and plasma analysis for Tiazofurin was performed by a sensitive and specific high-performance Chromatographie method described by Riley ef al. (13). The limit of detection for Tiazofurin in plasma was 40 ng/ml. The analytical method for detection of Tiazofurin in the urine was similar to that for plasma with slight modifications permitting greater specificity (10). The plasma concentration-time data were computer fitted to a 2-compartment open model with a zero-order infusion input and HOOT2 first-order elimination using NONLIN (11) with a weighing of 1/y. Lymphocyte Studies. It has been shown that lymphocytes are unu sually sensitive to the cytocidal effects of some nucleoside analogues (3, 6). To determine the effects of this C-nucleoside on peripheral lymphocyte subpopulations, blood samples were collected on Day 1 before treatment and 4 h after the final infusion on Day 5. Mononuclear cells were isolated, and the following lymphocyte subsets were quantitated by immunofluo- W rescence and flow cytometry as previously described (2): total T-cells; OH OH total B-cells; T-helpers; and T-suppressors. Chart 1. Structure of Tiazofurin.

Drug Formulation, Administration, and Treatment. Tiazofurin, pro RESULTS vided by the Division of Cancer Treatment, National Cancer Institute, was supplied in a freeze-dried dosage form in 10-ml vials containing Nineteen patients were entered in this trial. Patient character 1000 mg of drug plus sodium hydroxide for pH adjustment. This was istics are shown in Table 1. The median performance status of dissolved with 4.6 ml of sterile water for injection U.S.P., to obtain a final these patients was 1 (range, 0 to 4). The one patient with a concentration of 200 mg/ml yielding a clear, colorless solution. The performance status of 4 was bedfast secondary to a thoracic prescribed dose was further diluted in 100 ml of 0.9% normal NaCI spinal cord compression. A total of 24 courses was administered solution (saline) and administered i.v. over 30 min through a well running to the 19 patients. Five patients received 2 courses of Tiazofurin, i.v. line. The schedule of drug administration was daily for 5 days, while 14 patients received only one course. Four patients re repeated every 28 days. The starting dose was 550 mg/sq m. Dose escalations proceeded ceived an incomplete course (<5 days) of drug therapy, one due from 550 to 1100 to 1650 to 2200 mg/sq m. With the exception of the to dehiscence of an 18-day-old laminectomy wound on Day 3 of 2200-mg/sq m dose level where only 2 patients were treated, a minimum treatment (probably not drug related), and 3 patients had therapy of 3 patients was treated at all other dose levels. If after 4 weeks tumor discontinued secondary to drug toxicity (one on Days 3, 4, and progression and/or unacceptable toxicity did not occur at a specific dose 5). There was a total of 3 early deaths in this study. One patient level, the next dose level was started. There was no escalation of dose with synovial cell sarcoma and extensive pulmonary and bone for any individual patient. Study Parameters. Prior to the start of treatment and each subse Table 1 quent course, all patients had a complete history and physical examina Phase I Tiazofurin study: patient characteristics tion, hemogram, full chemistry profile, urinalysis, chest roentgenogram, electrocardiogram, and a 24-h urine collection for creatinine and uric acid Characteristics No. of patients clearance. Measurable lesions were documented on physical examina No. of patients/no, of courses 19/24 tion and with appropriate roentgenograms and nuclear scans. Men/women 16/3 During the time on treatment, patients were followed closely for signs of toxicity. Physical examinations, hemograms, and full chemistry profiles Age (yr) were repeated at a minimum of weekly intervals. Standard tumor re Median 60 Range 30-75 sponse criteria were used to evaluate the antitumor effect of the drug. These criteria included: (a) complete remission (disappearance of all Performance status clinical evidence of active tumor and tumor-related symptoms for at least Median 1 0-4 4 weeks); (o) partial remission (50% or greater decrease in the sum of Range the product of the perpendicular diameters of all measured lesions for at No. of patients with prior treatment least 4 weeks; (c) stable disease (objective tumor regression not quali Chemotherapy alone fying for partial remission but lasting for at least 4 weeks or a steady Radiotherapy and chemotherapy state not qualifying as increasing disease); and (d) progressive disease Radiotherapy alone

(a 25% or greater increase in the size of any measured lesion or the No. of patients with no prior treatment appearance of any new lesion). Patients were taken off study if unacceptable toxicity occurred from Tumor type drug administration or if objective tumor progression occurred following Non-small cell lung Colorectal one or more courses of Tiazofurin. Renal Pharmacokinetic Study. Blood samples were collected in heparinized Head and neck tubes on Days 1 and 5 immediately before drug infusion and at 5, 10, Sarcoma 20, 40, and 60 min and at 2, 4, 8, and 12 h postinfusion through a Hepatoma Cholangiocarcinoma heparin lock. Trough levels were obtained on Days 2 through 5. The

CANCER RESEARCH VOL. 45 JUNE 1985 2860 Downloaded from cancerres.aacrjournals.org on October 2, 2021. © 1985 American Association for Cancer Research. PHASE l CLINICAL TRIAL OF TIAZOFURIN mÃ©tastaseswas treated at 1100 mg/sq m and expired following fever, severe malaise, confusion, and nonspecific ST-T wave 1 day of treatment with hypotension and progressive respiratory changes on electrocardiogram following 4 days of Tiazofurin. deterioration. Autopsy findings demonstrated extensive chest Laboratory abnormalities included elevations in CPK (fractiona- wall adhesions with over 80% of the lung parenchyma replaced tion was MM band or skeletal muscle) and SCOT on Days 3 and with tumor. No significant cardiac findings were evident. In this 5, respectively. His confusion was felt to be secondary to hy- case, the contribution of Tiazofurin to the patient's demise is poxia, and he subsequently deteriorated rapidly and expired on uncertain, since no other episodes of hypotension occurred in Day 5. Postmortem examination revealed a purulent pericarditis this trial. A second patient with non-small cell lung cancer expired with cultures positive for Escherichia coli and Staphylococcus on Day 5 after receiving 4 days of Tiazofurin at 2200 mg/sq m. epidermidis. Additional findings included a right lower lobe pneu Death was felt to be secondary to sepsis which was complicated monia also positive for Â£.coli. Based on postmortem findings, it by a drug-induced pericarditis (described below). The final patient was felt likely that the pneumonia seeded the drug-induced who expired on Day 8 of the study had hepatoma and completed pericarditis, which together precipitated sepsis and his ultimate 5 days of therapy at 1650 mg/sq m. Based on autopsy findings, demise. The other 2 patients, one at 1650 and one at 2200 mg/ it was felt this patient had progressive liver failure secondary to sq m, developed pleuropericarditis following 3 and 4 days of intrahepatic biliary obstruction from marked tumor infiltration. Tiazofurin, respectively. This was characterized by shortness of Since none of the patients received more than 2 courses of breath, fever to 102Â°F,severe anterior pleuritic chest pain, and Tiazofurin in this trial, no definitive conclusion regarding the a pericardial rub. A minimal but reversible rise in SCOT was occurrence of cumulative toxicity could be made. noted in one patient, while CPK concentrations were normal in Toxicity. Drug-related effects were predominantly nonhema- both patients. Significant electrocardiogram changes occurred in tological. The number of patients treated at each dose level and the patient who received his second course at 1650 mg/sq m the toxicities are summarized in Table 2. The dose-limiting tox- and was characterized by diffuse ST-T wave elevations of 1 to icities in this study were pleuropericarditis observed in 3 patients 2 mm. Echocardiograms in both patients were negative for a and a general illness best described as a "viral-like" syndrome pericardial effusion. These 2 patients recovered from the pleu which was observed in 8 patients. This viral-like syndrome was ropericarditis over 3 to 6 days following institution of narcotics manifested most significantly by a severe generalized malaise, and nonsteroidal antiinflammatory agents. Due to the nature, rendering the patients nearly bedfast for a median of 3 days severity, and potential seriousness of the side effects encoun (range, 2 to 10). In all 8 patients who developed this syndrome, tered in the 2 of 2 patients treated at the 2200-mg/sq m dose 2 or more other symptoms were associated with the malaise, level, additional patient accrual at this dose was discontinued. including myalgias (50% of patients), proximal muscle weakness Efforts to determine the etiology of the pleuropericarditis were (13%), moderate to severe frontal headaches (38%), fever to unrevealing. Evaluations for an autoimmune etiology including 102Â°F(88%), nausea and vomiting (100%), and diarrhea (25%). rheumatoid factor, antinuclear antibody, and erythrocyte sedi The gastrointestinal side effects were generally mild to moderate mentation rate were negative. in intensity and never contributed to cessation of Tiazofurin One of 3 patients treated at 550 mg/sq m developed hyperur- therapy. One patient who received 1650 mg/sq m experienced icemia to 10.3 mg/dl (base line, 3.7 mg/dl) on Day 3 of treatment, severe malaise with myalgias which necessitated discontinuation which was accompanied by hyperuricosuria and uric acid crystals of the drug after Day 2. A second patient completed the 5-day in the urine. Allopurinol (300 mg) p.o. daily was instituted with a course of treatment but developed such a prolonged and more prompt decrease in uric acid without sequelae. Subsequently, all intense viral syndrome lasting 10 days that further treatment patients on other dose levels were pretreated with allopurinol, with Tiazofurin was deemed unacceptable by the patient and his and no other episodes of hyperuricemia were noted. physicians. Both patients treated at the 2200-mg/sq m dose Elevations in CPK were observed in a total of 5 patients level experienced this viral syndrome in combination with the receiving 7 courses of Tiazofurin. CPK abnormalities ranged from pleuropericarditis described below. 224 to 15,480 Ill/liter (normal range, 21 to 215 ID/liter) and were The other dose-limiting toxicity, pleuropericarditis, was ob more frequent at the higher dose levels. The median-peak CPK served in one patient treated with a second course of Tiazofurin concentration was 3260 Ill/liter and occurred by median Day 5. at 1650 mg/sq m and in 2 patients receiving their first course at Abnormal concentrations were reversible and returned to normal 2200 mg/sq m. One patient treated at 2200 mg/sq m was a 67- range by median Day 15. In all cases, the enzyme fractionated year-old male Caucasian who developed shortness of breath, to pure MM band or skeletal muscle CPK. Aldolase measure-

Table2 Toxicity of Tiazofurin No. of courses with toxicity as follows

skin Dose (mg/sq of patients/ uric syn desquama m)550 no. ofcourses3/3 acid1 SCOT1 CPKNot drome1 carditis1 tis4(40)Mucositis2(20)Palmar tion2(20) (33)8'6Elevated (33) measured 6/9c 1100 6 (66) 1 (11) (11) 8/10Â° 1650 6 (60) 3(30) 5 (50) (10) 2/2cElevated 2200No. 2 (100)Elevated 1(50)Viral-like 2(100)Pleuroperi 2(100)Conjunctivi a Numbers in parentheses, percentage of courses with that toxicity. * Patients at all other dose levels were pretreated with allopurinol. c Two incomplete courses were administered.

CANCER RESEARCH VOL. 45 JUNE 1985 2861

Downloaded from cancerres.aacrjournals.org on October 2, 2021. © 1985 American Association for Cancer Research. PHASE l CLINICAL TRIAL OF TIAZOFURIN ments in 3 patients were normal. One patient at 1100 mg/sq m a significant granulocytopenia and thrombocytopenia. Nadir developed a marked increase in CPK to a level of 15,400 ID/liter granulocyte counts for these 3 patients were 150, 667, and 800/ by Day 6. A simultaneous and marked increase in SCOT to 10 cu mm for the above respective doses. The corresponding times the pretherapy value occurred without deterioration in platelet nadirs in the same 3 patients were 51,000,104,000, and other liver or renal function measurements. Urine myoglobin 51,000/cu mm, respectively. All of these patients had received measurements in this patient were normal, and CPK fractionated previous extensive chemotherapy (no prior 1,3-bis(2-chloro- to skeletal muscle. On Day 8, a gastrocnemius muscle biopsy ethyl)-1 -nitrosourea or mitomycin C) which might have accounted was performed, showing only disuse atrophy of Grades 1 and 2 for this more severe drug-induced toxicity. with a normal microstructure. The CPK and SGOT levels declined In 12 courses, a >2-g/dl decline in pretreatment hemoglobin rapidly between Days 7 and 9 and reverted to normal by Day levels was observed over the 28-day period. This decline oc 21. Throughout this event, the patient was asymptomatic without curred at all dose levels but was more frequent at doses >1100 muscle soreness or weakness. Three other patients with the mg/sq m. RBC transfusions were required in 5 patients. The CPK abnormality had an associated but only minimal rise in median time to hemoglobin nadir was 14 days (range, 3 to 24 SGOT. Two patients with CPK elevations during a first course days). Although a majority of the patients demonstrated an of Tiazofurin had normal CPK and SGOT measurements through anemia prior to therapy (median pretreatment hemoglobin, 11.2 out the second treatment period. g/dl), Tiazofurin appeared to exhibit some effect on RBC with a Liver function abnormalities, characterized most commonly by further decline in hemoglobin levels. While several factors could elevations in SGOT, occurred in 15 courses. The median increase have contributed to this progressive anemia, including frequent in pretreatment SGOT measurements was 36 Ill/liter and oc phlebotomy, previous chemotherapy, and chronic disease, we curred by median Day 6. With the exception of 2 patients who still suspect a drug-induced component. expired early in the study, one on Day 5 with sepsis and the Responses. No objective responses were noted in this clinical other on Day 8 from progressive hepatoma, SGOT abnormalities trial. were reversible and returned to base line by median Day 13. Pharmacokinetics. Nine patients were studied, 3 of whom One patient, described above with the marked CPK abnormality, received incomplete 5-day courses (Patients 5, 7, and 9). As developed a significant but reversible increase in SGOT from 32 noted in Table 4, peak plasma levels postinfusion on Day 1 on Day 1 to 330 ID/liter on Day 6. No other liver function ranged from 57.1 to 171.4 /Â¿g/ml,depending on the total dose abnormalities were noted in this patient. Minimal elevations in administered and duration of infusion. There was no significant lactic dehydrogenase and alkaline phosphatase occurred in sev drug accumulation over the treatment period. eral courses; however, these changes did not appear to be drug The kinetic parameters derived from the data points obtained associated. Only one patient developed a rise in total bilirubin, on Days 1 to 5 for all 9 patients are represented in Table 5. The which went from 0.6 on Day 1 to 2.3 mg/dl on Day 4. This was harmonic mean distribution half-life (tv, a) was 6.6 min, followed associated with a reversible rise in SGOT to twice normal. In this by a harmonic mean elimination half-life (f./2ÃŸ)of 7.56 h. The patient, both values reverted to base line by Day 7. apparent volume of distribution for the central compartment was Other toxicity included conjunctivitis observed in 4 patients at 14.23 liters/sq m. The steady-state volume of distribution was the 1650-mg/sq m dose level. Onset of the conjunctivitis was as approximately 30 liters/sq m. The mean plasma clearance was early as Day 2 and resolved with artificial tears or steroid eye 2.93 Â±1.53 liters/h/sq m. The total cumulative urinary excretion drops. Three patients developed mild mucositis at the 1100- and of Tiazofurin ranged from 15 to 49%. The percentage excreted 1650-mg/sq m dose levels. Finally, 3 patients who received 1650 renally did not appear to appreciably change with time. mg/sq m experienced mild dermal toxicity, manifested by an Tissue samples were obtained at autopsy from 2 patients, one intertriginous zone rash in one patient and desquamation of the who received Tiazofurin (2200 mg/sq m) for 4 days and the palms of the hands in 2 patients. No renal or neurotoxicity was other, 1100 mg/sq m for 1 day (Table 6). The highest tissue noted in this study. concentrations were found in the pancreas and kidney, respec Myelosuppressive Toxicity. Myelosuppression was neither tively. Variation in these Tiazofurin tissue concentrations may dose limiting nor dose related in this study. Sixteen patients reflect a difference in the total dose and number of days of drug receiving 21 courses were Ã©valuablefor the hematological effects administration. of the drug (Table 3). Only one patient was Ã©valuableat the Simultaneous plasma and CSF were obtained from one patient 2200-mg/sq m dose level. A total of 3 patients, treated at 3 treated at 1650 mg/sq m on Day 5, 30 min post-Tiazofurin different dose levels (1100,1650, and 2200 mg/sq m), developed administration. The plasma and CSF concentrations of Tiazofurin

Table 3 Hematological effects of Tiazofurin countsGranulocytesnadir Dose (mg/sq of pa m/day for five tients/no, of (xl03/cu days)550 courses3/3&Lwfâ€¢?!?Hemoglobin(g/dl)8.9(8.1-9.6)a mm)2,601 (cells/cu mm)335(256-414) (1,280-5,320) 1,100 9.1 (7.3-10.3) 2,964(150-11,392) 318(51-466) 1,650 10.8(7.0-12.4) 2,688(667-21,098) 313(104-630) 2,200No. 7.8Median 800Platelets 51 8 Numbers in parentheses, range of nadir counts 6 One not Ã©valuablefor hematological toxicity c Two incomplete courses.

CANCER RESEARCH VOL. 45 JUNE 1985 2862

Table 4 Tiazoturinplasma concentrations dura concen levels(Â¿ig/ml)atthe tion(min)Day129 tration(jig/ml)Day days22.2following surface Patient1 (yr)58 (kg)60.5 area (sqm)1.72 m)550 178.6 551.3

2 60 98.0 1.54 550 847 25 33 58.8 9.3 10.2 12.2 3 63 108.0 1.60 1100 1760 30 30 57.156.558.8 1.2 2.015.27.410.82.6 4 48 110.6 2.28 1100 2508 32 303840Peak 52.984.5 5.1 10.84.612.9 7.58.915.0 5' 47 59.9 1.72 1100 1900 30 1.1 6 62 95.8 2.13 1650 3514 34 87.4 3.2 7* 64 84.7 2.10 1650 3465 30 122.7 10.0 8 59 87.5 2.08 1650 3400 30 85.6 84.0Trough 7.8 7.8 tfAge 67Wt 57.7Body 1.68Dose(mg/sq 2200mg9463696Infusion 29DayS30 171.4Day 21.239.50.618.843.523.053.432.8 8 Incompletecourses (Patient 5, 3 days; Patient 7, 2 days; Patient 9, 4 days).

Tables Pharmacokineticparameters ol tiazoturin m)Central5.5317.9915.5024.0812.0326.483.2314.818.3914.23of distribution (liters/sq (mg/sqm)5505501100110011001650165016502200t,aclearance(liters/h/sq Patient123456789Dose a(HI0.300.020.280.750.261.700.090.440.300.11Â°fi/20(h)7.289.595.0613.993.709.358.7910.9310.287.56aPlasmam)2.201.313.902.456.224.002.002.561.722.93state20.1218.1627.1246.7129.0743.8023.5737.6724.0630.03

Â±1.53"Volumes 10.32* Â±7.89Steady Â± mean."MeanÂ±SD.Harmonie

Table 6 furinwas nondetectable. Tissuelevels (Â»g/gtissue!at autopsy from 2 patients treated with Tiazofurin Lymphocyte Studies. Sixteen of 19 patients were Ã©valuable (2200 mg/ (1100 mg/ for the effect of Tiazofurin on absolute lymphocyte counts. Four sq m for 4 days). sq m for 1 day), TissuePancreasLiverSpleenHeartAdrenalMuscle,Day626769616255444235252322201716SampleDay2a1223171722113241982119221811of 21 Ã©valuablecourses demonstrated no effect on total lympho cytes. The median nadir absolute lymphocyte count for the remaining 17 courses was 465 per n\ (range, 0 to 1872). The median time from initiation of treatment to nadir lymphocyte count was 9 days (range, 5 to 33). The lymphocyte count diaphragmKidneySmall returned to pretreatment levels by median Day 15 (range, 6 to bowelNodeProstateLungBladderThyroidFatOvaryPericardiumMyometriumLung41 ). There was no increase in lymphocytotoxicity in dose esca lations above 1100 mg/sq m. Lymphocyte subsets were measured in 9 patients receiving 550, 1100, and 1650 mg of Tiazofurin per sq m. A significant decrease (P value, 0.04) in total lymphocytes was observed between the pretreatment and posttreatment values. However, there was no selective effect of Tiazofurin on total T-, total B-, helper, or suppressor T-cell subclasses. Therefore, all major withtumorStomachSample lymphocyte subpopulations appeared to be equally sensitive to aAnalysis provided by Dr. Louis Malspeis,Ohio State UniversityCancer Center. Tiazofurin.

DISCUSSION were 49.5 and 9.7 ^g/ml, respectively (analysis provided by Dr. Louis Malspeis, Ohio State University). These data demonstate Tiazofurin, a C-nucleoside with anticancer activity both in vitro that approximately 20% of the plasma concentration was found and in animal tumor models, was evaluated in this Phase I trial in the CSF. utilizing a 5-day, every-28-day schedule. The dose-limiting tox- Tear samples were collected from 2 patients (Nos. 7 and 8) icities were pleuropericarditis and a general illness best described using the Schirmer tear test at the onset of their conjunctivitis. as a viral-like syndrome. The pleuropericarditis observed in 3 The tear-laden Schirmer's tapes were diluted in 2 ml of 0.9% patients was clinically significant during a second course of sodium chloride and analyzed for Tiazofurin. Whether due to the Tiazofurin in one patient at 1650 mg/sq m and during a first sampling procedure or the lack of distribution into tears, Tiazo course in 2 of 2 patients treated at 2200 mg/sq m. Significant

CANCER RESEARCH VOL. 45 JUNE 1985 2863

electrocardiogram changes demonstrating diffuse ST-T wave rabbit, and dog, urinary excretion accounted for between 40 and elevations were associated with the symptom complex of short 90% of the administered dose (1). The contribution of anabolism ness of breath, fever, pleuritic chest pain, and pericardial rub. and hepatobiliary excretion to the elimination of Tiazofurin was Nonsteroidal antiinflammatory agents successfully treated the not determined. In rodents, fecal excretion accounted for only 2 drug-induced pleuropericarditis in 2 patients. We did not, how to 3% of the administered dose. Over the range of doses ever, investigate their potential as a prophylactic measure in this examined in the present trial (550 to 2200 mg/sq m), the phar study. An autoimmune evaluation including rheumatoid factor, macokinetic parameters appeared to be independent of dose or antinuclear antibody, and erythrocyte sedimentation rate to de concentration. termine the etiology of this potentially serious toxicity was un- Tissue samples obtained in 2 patients at autopsy showed the revealing. highest concentration of Tiazofurin in the pancreas and kidney, The viral-like syndrome was observed in 8 patients and was respectively. In view of these findings, none of the patients was also considered dose limiting. The illness was manifested by noted to have abnormal glucose levels or progressive deterio severe malaise, rendering the patients nearly bedfast for 2 to 10 ration of renal function. Tissue distribution studies in animals (1) days. This syndrome was also associated with 2 or more of the found the majority of "Tiazofurin equivalents" in the large intes following symptoms: headaches; myalgias; proximal muscle tine, which unfortunately was not sampled in our patients. Si weakness; fevers; nausea; vomiting; and diarrhea. These drug- multaneous plasma and CSF concentrations of Tiazofurin were induced toxicities may, in fact, be independent of each other; measured in one patient and demonstrated that Tiazofurin however, they appeared temporally related. With the exception crosses the blood-brain barrier. These data support the animal of the first dose level, this viral-like syndrome occurred at all pharmacology studies (1) and may provide rationale for the other doses but was more frequent at the higher dosage levels. neurotoxicity reported by some investigators in clinical trial.5 Another nonhematological toxicity with serious potential was As a result of the findings in this Phase I study, the maximally hyperuricemia observed in one patient at the first dose level. tolerated dose of Tiazofurin on a 5-day schedule was 1650 mg/ This toxicity was hypothetically predicted, because of the accu sq m. Because this dose was associated with more frequent and mulation of inosine-5'-monophosphate dehydrogenase, although severe toxicity, which was not always predictable or reproduci it could not be tested in the animal species due to differences in ble, the recommended dose for Phase II evaluation is 1100 mg/ purine pathways. Additional preclinical studies with Tiazofurin sq m/day for 5 days. However, exploration of other schedules and allopurinol were subsequently initiated, and no loss of anti- which might allow administration of more Tiazofurin combined tumor activity was observed (12). Therefore, in the present Phase with biochemical studies including thiazole-4-carboxamide ade- I trial, all patients at other dose levels were pretreated with nine dinucleotide measurements would be desirable. allopurinol, and no other elevations in uric acid were noted. It is recommended that future trials also institute measures to prevent ACKNOWLEDGMENTS this potentially serious drug-induced toxicity. Other toxicities observed with Tiazofurin administration in The authors would like to thank the staff of the Clinical Research Unit at the cluded elevations in skeletal muscle CPK (MM band only) and Audie Murphy Veterans Administration Hospital for their assistance in patient care and Mary Adams for her secretarial assistance in preparing this manuscript. We SCOT, conjunctivitis, mucositis, and desquamation of the palms also wish to thank Dr. Louis Malspeis of Ohio State University Cancer Center for of the hands. All toxicities were reversible, and no liver or renal performing the plasma, CSF, and tissue analysis of the patient treated at 1100 mg/ sq m. deterioration developed. The myelosuppressive effects of Tiazofurin, including leukopenia and thrombocytopenia, were neither dose limiting nor dose REFERENCES related in this trial. These effects were most apparent in heavily 1. Arnold, S. T., Jayaram, H. N., Harper, G. R., Utters!, C. L, Malspeis, L, pretreated patients. A decline in hemoglobin levels, also unre Desouza, J. J. V., Staubus, A. E., Ahluwalia, G. S., Wilson, Y. A., Cooney, D. lated to dose, was noted in a majority of the patients without A., and Johns, D. G. The distribution and metabolism of Tiazofurin in rodents, rabbits, and dogs. Drug Metab. 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Teresa J. Melink, Daniel D. Von Hoff, John G. Kuhn, et al.

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