Pharmacokinetics of the hypoxic cell cytotoxic agent tirapazamine and its major bioreductive metabolites in mice and humans: retrospective analysis of a pharmacokinetically guided dose-escalation strategy in a phase I trial

Tirapazamine (3-amino-1,2,4-benzotriazine-1,4-di-N-oxide; SR 259075) is a selective hypoxic cell cytotoxic agent that is bioreductively activated in tumours to a reactive-drug free radical. Preclinically the agent has been shown to possess additive and synergistic anti-tumour activity in combination with radiotherapy and chemotherapy regimens. In the present study the pharmacokinetics and metabolism of tirapazamine were investigated in mice and patients as part of pre-clinical and phase I investigations. The objectives of this work were twofold; firstly, to evaluate retrospectively the utility of a pharmacokinetically guided dose-escalation (PGDE) strategy for tirapazamine, and secondly, to investigate if pharmacologically relevant plasma concentrations could be achieved at tolerable doses. Pharmacokinetic studies for PGDE were conducted in mice at four dose levels ranging from one-tenth of the LD10 to the LD50. The AUC at the LD10 (2932 micrograms ml-1 min) was used to determine a target AUC value of 1173 micrograms ml-1 min (equivalent to 40% of the mouse LD10 AUC) for clinical studies. A phase I study to investigate the tolerance of a single i.v. infusion of tirapazamine (once every 3 weeks) was initiated with close pharmacokinetic monitoring. The starting dose (36 mg/m2) was based on toxicity data obtained in the mouse, rat and dog. Doses were escalated by increases in the volume and duration of infusion. A retrospective analysis of the pharmacokinetic and toxicity data was then made to determine the utility of a PGDE approach. The drug exhibited a steep dose-lethality relationship in mice (LD10 294 mg/m2, LD50 303 mg/m2). The major gross toxicities were body-weight loss (15-20%), pilo-erection and hypoactivity at all dose levels. Sporadic ptosis and conjunctivitis were observed at doses of > 300 mg/m2. The plasma elimination of tirapazamine fitted a monoexponential open model, with rapid elimination from the plasma (t1/2 = 36 +/- 0.65 min) occurring at the LD10 dose of 294 mg/m2. A 10.3-fold increase in dose resulted in a 25.0-fold increase in AUC. Clinically, doses were escalated over the range of 36-450 mg/m2. Ototoxicity (tinnitus and reversible hearing loss) was dose-limiting at 450 mg/m2 and the MTD was 390 mg/m2 for this schedule. Pharmacokinetic analyses in patients revealed that the elimination of tirapazamine in patients was generally bi-phasic, with low inter-patient variability being found in clearance. A 12.5-fold increase in dose resulted in a 19.0-fold increase in AUC. There was good quantitative agreement in metabolite formation between mice and humans with respect to the two- and four-electron bioreductive metabolites. AUC values recorded for tirapazamine at the MTD of 390 mg/m2 (range 1035-1611 micrograms ml-1 min) were similar to the target AUC in mice. Importantly, these levels are consistent with the levels required for radiation-dose enhancement and effective combination with cisplatin in mice. Given (a) the similarities in plasma pharmacokinetics and metabolism observed at the target AUC/MTD in mice, rats, dogs and humans, (b) the similar degree of plasma protein binding seen between species and (c) the relatively low inter-patient variability noted in drug clearance, a successful PGDE approach should have been feasible. The results also indicate that potentially therapeutic levels of tirapazamine are achievable in patients at tolerable doses.

Phase I trial of concurrent tirapazamine, cisplatin, and radiotherapy in patients with advanced head and neck cancer

PURPOSE

To determine the maximum-tolerated dose of tirapazamine when combined with cisplatin and radiation in patients with T3/4 and/or N2/3 squamous cell carcinoma of the head and neck.

PATIENTS AND METHODS

The starting schedule was conventionally fractionated radiotherapy (70 Gy in 7 weeks) with concomitant cisplatin 75 mg/m2 and tirapazamine 290 mg/m2 (before cisplatin) in weeks 1, 4, and 7 and tirapazamine alone 160 mg/m2 three times a week in weeks 2, 3, 5, and 6. Positron emission tomography scans for tumor hypoxia (18F misonidazole) were performed before and during radiotherapy.

RESULTS

We treated 16 patients with predominantly oropharyngeal primary tumors, including 10 patients with T4 or N3 disease. Febrile neutropenia occurred toward the end of radiotherapy in three out of six patients treated on the initial dose level. Two of these patients also developed grade 4 acute radiation reactions. Another 10 patients were treated with the same doses, but the week 5 and week 6 tirapazamine doses were omitted. This resulted in less neutropenia and only one dose-limiting toxicity (DLT) (febrile neutropenia), and eight out of 10 patients completed treatment without any dose omissions. In these 10 patients, the acute radiation toxicities were not obviously enhanced compared with chemoradiotherapy regimens using concurrent platinum and fluorouracil. 18F misonidazole scans detected hypoxia in 14 of 15 patients at baseline, with only one patient having detectable hypoxia at the end of treatment. With a median follow-up of 2.7 years, the 3-year failure-free survival rate was 69% (SE, 12%), the 3-year local progression-free rate was 88% (SE, 8%), and the 3-year overall survival rate was 69% (SE, 12%).

CONCLUSION

DLT was due unexpectedly to febrile neutropenia, which could be overcome by omitting tirapazamine in weeks 5 and 6. The combination of tirapazamine, cisplatin, and radiotherapy resulted in remarkably good and durable clinical responses in patients with very advanced head and neck cancers. It warrants further investigation.

Comparison of urinary desmosine excretion in patients with chronic obstructive pulmonary disease or cystic fibrosis

Neutrophil elastase is involved in the pathogenesis of several pulmonary diseases; a strategy for monitoring in vivo elastase activity is to measure changes in biochemical markers. The objective of this study was to determine whether differences in the urinary excretion of the elastin crosslinks, desmosine and isodesmosine (which are unique amino acid products of elastase activity), could be discerned between groups of patients with chronic obstructive pulmonary disease (COPD) or cystic fibrosis (CF), and non-diseased, age-matched controls. Twenty-four-hour urine collections were analysed to eliminate variations in excretion throughout the day, and urine was collected on four separate days in 29-31 subjects/group to investigate the variability in desmosines excretion among the groups. Both sets of patient populations had significantly more variable desmosines readings (higher standard deviations) relative to their respective age-matched control group. The means for three adult groups (COPD, controls and a COPD-smoker subset) ranged from 28.4 to 35.5 pmol desmosines/mg creatinine and there were no differences among the groups. Values in children were higher: 55 pmol desmosines/mg creatinine in the non-CF children and 77 pmol desmosines/mg creatinine for the CF group (P<0.01 vs. age-matched controls). The results of this study show that urinary desmosines, as a surrogate marker for enhanced elastase activity, are more highly variant in both patient populations relative to age-matched controls, and an overall increase in the mean value is further observed in patients with cystic fibrosis.

Tirapazamine plus cisplatin versus cisplatin in advanced non-small-cell lung cancer: A report of the international CATAPULT I study group. Cisplatin and Tirapazamine in Subjects with Advanced Previously Untreated Non-Small-Cell Lung Tumors

PURPOSE

A phase III trial, Cisplatin and Tirapazamine in Subjects with Advanced Previously Untreated Non-Small-Cell Lung Tumors (CATAPULT I), was designed to determine the efficacy and safety of tirapazamine plus cisplatin for the treatment of non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with previously untreated NSCLC were randomized to receive either tirapazamine (390 mg/m(2) infused over 2 hours) followed 1 hour later by cisplatin (75 mg/m(2) over 1 hour) or 75 mg/m(2) of cisplatin alone, every 3 weeks for a maximum of eight cycles.

RESULTS

A total of 446 patients with NSCLC (17% with stage IIIB disease and pleural effusions; 83% with stage IV disease) were entered onto the study. Karnofsky performance status (KPS) was >/= 60 for all patients (for 10%, KPS = 60; for 90%, KPS = 70 to 100). Sixty patients (14%) had clinically stable brain metastases. The median survival was significantly longer (34.6 v 27. 7 weeks; P =.0078) and the response rate was significantly greater (27.5% v 13.7%; P <.001) for patients who received tirapazamine plus cisplatin (n = 218) than for those who received cisplatin alone (n = 219). The tirapazamine-plus-cisplatin regimen was associated with mild to moderate adverse events, including acute, reversible hearing loss, reversible, intermittent muscle cramping, diarrhea, skin rash, nausea, and vomiting. There were no incremental increases in myelosuppression, peripheral neuropathy, or renal, hepatic, or cardiac toxicity and no deaths related to tirapazamine.

CONCLUSION

The CATAPULT I study shows that tirapazamine enhances the activity of cisplatin in patients with advanced NSCLC and confirms that hypoxia is an exploitable therapeutic target in human malignancies.

Concurrent tirapazamine and radiotherapy for advanced head and neck carcinomas: a Phase II study

PURPOSE

To evaluate the efficacy and toxicity of tirapazamine, a hypoxic cytotoxin, combined with conventional radiotherapy (RT) for advanced head and neck carcinomas.

MATERIALS AND METHODS

From Oct. 1994 to Nov. 1996, 40 patients with stage III or IV carcinomas of the head and neck were enrolled in a Phase II trial to receive conventional RT (70 Gy in 7 weeks) with concurrent tirapazamine (159 mg/m2 intravenously, 3 times per week for 12 doses). One patient subsequently withdrew from the protocol treatment, and was excluded from analyses. Among the 39 cases, the primary sites were located in the oropharynx (n = 28), supraglottic larynx (n = 6), or hypopharynx (n = 5). Twenty-seven patients had T3 or T4, and 27 had N2 or N3 disease.

RESULTS

Thirty-two (82%) patients received full 12 drug doses. Thirty-two patients (82%) received full 70 Gy of RT. The most frequent drug toxicities were muscle cramps (77%) and nausea/vomiting (62%), usually grade 1 or 2. Overall, 13 patients (33%) experienced grade 3 or 4 drug-related toxicities. No excessive RT-associated acute normal tissue reactions were observed. With a median follow-up of 13 months, the 1-year and 2-year local control rate was 64% and 59% respectively.

CONCLUSION

The tirapazamine regimen was well tolerated with a compliance rate of 82%. The toxicity of RT with concurrent tirapazamine was acceptable in treating advanced head and neck carcinomas. The disease control trend was encouraging. Further clinical studies are warranted.

Tirapazamine with cisplatin in patients with advanced non-small-cell lung cancer: a phase II study

PURPOSE

A phase II study was conducted to evaluate the safety and efficacy of tirapazamine combined with cisplatin for the treatment of patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Forty-four patients with stage IIIB/IV NSCLC were treated with a combination of tirapazamine and cisplatin. Patients received tirapazamine 260 mg/m2 administered intravenously over 2 hours, followed 1 hour later by cisplatin 75 mg/m2 administered over an additional hour, repeated every 21 days. The duration of therapy was meant to be limited to four cycles for nonresponders and eight cycles for responders.

RESULTS

Ten of 44 patients (23%) showed a partial response. The estimated median survival for all patients was 37 weeks. Toxicities were treatable and included grade 3 nausea or vomiting (25%), fatigue (27.3%), and muscle cramps (4.5%). No dose reductions were necessary.

CONCLUSION

The results show that tirapazamine can safely be added to cisplatin. Both the median survival and response rate observed strongly suggest that tirapazamine with cisplatin is more active than cisplatin alone.

Tirapazamine-cisplatin: the synergy

Tirapazamine is a novel bioreductive agent with selective cytotoxicity against hypoxic tumour cells. Synergy with cisplatin and other chemotherapeutic agents has been shown in preclinical trials. Pharmacokinetic studies of tirapazamine have revealed that exposure increases with dose over the range of 18-450 mg m(-2) for a single dose and of 9-390 mg m(-2) for multiple doses. Plasma clearance is high. Tirapazamine has been clinically tested in combination with cisplatin at escalating doses in a phase I trial and at therapeutic doses in three separate phase II trials in patients with advanced non-small-cell lung cancer (NSCLC) in 11 study centres. Limiting toxicity for tirapazamine at an intravenous dose of 390 mg m(-2) was acute, reversible hearing loss. Other frequently observed side-effects included muscle cramping and gastrointestinal symptoms. Tirapazamine did not cause myelosuppression, and no toxic deaths were reported in these trials. The anti-tumour efficacy against previously untreated, advanced NSCLC was evaluated by cumulative intent-to-treat analysis of 132 patients. The objective response rate (confirmed by two independent measurements) was 25% [confidence interval (CI) 17.8-33.33], with a median survival of 38.9 weeks (CI 29.4-49.9). The efficacy of tirapazamine plus cisplatin shown in these trials was better than that of historical controls with cisplatin monotherapy. Two large-scale international trials have been conducted, involving more than 70 centres, to confirm these results. The CATAPULT I trial compares tirapazamine plus cisplatin with cisplatin and has finished accrual with 446 patients. The CATAPULT II trial, which is comparing tirapazamine plus cisplatin with etoposide plus cisplatin, had enrolled 550 patients by June 1997. Follow-up is ongoing. Tirapazamine is the promising first drug from a new class of cytotoxic agents with a novel mechanism of action. It can be effectively combined with cisplatin, and possibly with other agents, because of its safety profile and lack of overlapping dose-limiting toxicity, such as myelosuppression. The combination of tirapazamine and cisplatin appears to be safe and effective in the treatment of NSCLC.

Phase II study of the combination of the novel bioreductive agent, tirapazamine, with cisplatin in patients with advanced non-small-cell lung cancer

PURPOSE

Tirapazamine is a bioreductive compound synergistic with cisplatin in preclinical testing. This phase II study was conducted to evaluate the efficacy and toxicity of tirapazamine with cisplatin in patients with advanced non-small-cell lung cancer.

PATIENTS AND METHODS

Twenty patients with unresectable stage III-B and IV non-small-cell lung cancer who had not received prior chemotherapy were given tirapazamine (390 mg/m2) intravenously (i.v.) over two hours followed one hour later by cisplatin (75 mg/m2) i.v. over one hour every 21 days.

RESULTS

Five of 20 patients (25%) had major objective responses (95% confidence interval, 11%-50%). Median duration of response was eight months with a one-year survival of 40%. Toxicities included temporary hearing loss (25%), muscle cramping, diarrhea, skin rash and nausea/vomiting. No grade 3 or 4 hematologic or renal toxicity was observed.

CONCLUSIONS

The combination of tirapazamine plus cisplatin appears to be safe and active in the treatment of advanced non-small lung cancer without a substantial increase in toxicity compared to cisplatin alone. A phase III randomized study compared the combination to cisplatin alone has completed accrual. Further evaluation of tirapazamine with other active agents and in multi-modality therapy is warranted.

Phase II trial of tirapazamine combined with cisplatin in chemotherapy of advanced malignant melanoma

PURPOSE

A phase II study was undertaken to determine the efficacy of tirapazamine (TPZ) combined with cisplatin (cDDP) in patients with metastatic melanoma.

PATIENTS AND METHODS

Between June 1994 and November 1995, 48 patients with metastatic melanoma were treated with TPZ (260 mg/m2, administered intravenously over two hours) followed in one-hour by cDDP (75 mg/m2 over one hour) every 21 days. Sixteen patients had received prior chemotherapy, and 13 of these had failed to respond to prior cDDP. None of the patients had symptomatic brain metastasis.

RESULTS

Nine patients had partial responses, with an overall response rate of 19% (95% confidence interval (95% CI) of 9%-33%). The median duration of response was six months. None of the responders had received prior chemotherapy. Responses were seen in 8 (33%, confidence interval of 16%-55%) of 24 patients with primary cutaneous melanoma who had received no prior chemotherapy and in the only patient with previously untreated conjunctival melanoma. There were no responders among the seven patients with choroidal melanoma and 16 patients with previously treated cutaneous melanoma. Two patients with partial responses were rendered free of gross disease surgically three months after completing eight courses of TPZ-cDDP; they remain free of tumor recurrence. Responses were seen in lymph nodes (27%), lung (26%), skin (20%), adrenal gland (20%), soft tissues (17%) and liver (17%). Common toxicities included muscle cramps, fatigue, gastrointestinal effects and peripheral neuropathy. Fatigue, nausea, vomiting, anorexia, and muscle cramps were grade 3 or 4 in less than 10% of the courses. Neutropenia and thrombocytopenia were rare.

CONCLUSION

The TPZ-cDDP combination has definite activity against chemotherapy-naïve patients with cutaneous melanoma and warrant further studies in combination with other cytotoxic agents.

Phase I trial of tirapazamine in combination with cisplatin in a single dose every 3 weeks in patients with solid tumors

PURPOSE AND METHODS

Tirapazamine (SR4233, WIN 59075) is a benzotriazine-di-N-oxide bioreductive agent that is selectively activated to a reactive DNA-damaging species in hypoxic tumors. Preclinical studies show that synergistic antitumor activity results from a schedule-dependent interaction between tirapazamine and several cytotoxic drug classes, including cisplatin. In a phase I combination study, tirapazamine (130 to 260 mg/m2) was administered as a 1-hour intravenous (IV) infusion beginning 3 hours before cisplatin (75 to 100 mg/m2). Thirteen patients received 41 courses of therapy. These patients had an excellent performance status and were not heavily pretreated. The predominant diagnosis was lung cancer.

RESULTS

The major acute side effects were nausea and vomiting, which were controlled with an intensive antiemetic regimen. Other acute effects included diarrhea and muscle cramping, while with repeated dosing, anorexia and fatigue predominated. Full doses of each agent were well tolerated in combination, although in this previously treated population, fatigue increased markedly after three cycles of therapy. Partial responses were observed in two patients (one with non-small-cell lung cancer and one with breast cancer), and a minor response occurred in a patient with mesothelioma. Tirapazamine pharmacokinetics were linear with respect to increasing dose with a mean maximum plasma concentration (Cmax) of 5.97 +/- 2.25 microg/mL and an area under the concentration-time curve (AUC) of 811.4 +/- 311.9 microg/mL.min at 260 mg/m2. These results are consistent with other ongoing single-agent and combination studies and indicate that therapeutically relevant levels of tirapazamine are achievable in patients based on animal models. The mean cisplatin AUC was 285.6 +/- 46.4 microg/mL.min with mean Cmax values of 3.38 +/- 0.43 microg/mL at 75 mg/m2. The clearance of cisplatin was unaffected by coadministration with tirapazamine.

CONCLUSION

This trial shows that in previously treated patients, full doses of cisplatin are well tolerated with increasing doses of tirapazamine up to 260 mg/m2. The observation of clinical responses in this trial supports the phase II investigation of this regimen.

Phase I and pharmacokinetic study of tirapazamine (SR 4233) administered every three weeks

Tirapazamine (SR 4233; 3-amino-1,2,4-benzotriazine-1,4-di-N-oxide) is a bioreductive agent exhibiting up to 200 x greater toxicity for hypoxic cells as compared to oxygenated cells. In murine studies, a selective increase in tumor kill was observed when tirapazamine was coadministered with other agents, notably cisplatin. A Phase I study of single-agent tirapazamine administered i.v. every 3 weeks was conducted to determine the toxicity of a schedule for use with systemic chemotherapy. A total of 28 patients were given 50 courses of tirapazamine at doses ranging from 36-450 mg/m2. No tumor responses were observed. Reversible deafness and tinnitus were dose-limiting, with ototoxicity observed in 1 of 6 patients treated at 330 mg/m2, 1 of 4 patients treated at 390 mg/m2, and 3 of 3 patients treated at 450 mg/m2. Muscle cramps, nausea, and vomiting were also observed. Pharmacokinetic studies revealed a greater than dose-proportional increase in the area under the plasma concentration x time curve (AUCs) of the two major metabolites. Patients who developed ototoxicity generally showed higher plasma AUC values for the parent drug and metabolites. The mean plasma tirapazamine AUC at 330 mg/m2 was 1026.5 microgram/ml x min (range 863. 8-1252.3), but no pharmacokinetic data are available for the solitary patient who developed otoxicity at this dose level. These AUC values were in the (estimated) range required for therapeutic effect in murine studies. Ototoxicity was not observed when the AUC of tirapazamine was equal to or less than 1252 microgram/ml x min. The dose of 330 mg/m2 was therefore chosen as an appropriate level for combination chemotherapy studies.

Muscle cramping in phase I clinical trials of tirapazamine (SR 4233) with and without radiation

PURPOSE

Tirapazamine (SR 4233) is a benzotriazine di-N-oxide which acts as a hypoxic cytotoxic agent and as a radiation enhancer when given shortly before or after radiation. Three Phase I clinical trials were designed to determine the maximum tolerated dose, toxicities, pharmacokinetics, and effects on irradiated tumors and normal tissues.

METHODS AND MATERIALS

Tirapazamine 9 mg/m2 to 21 mg/m2 was given i.v. 1/2 to 1 h prior to irradiation on a multiple dose schedule of 10 consecutive doses. This was later revised to a three times-per-week schedule for 12 doses. In a second clinical trial, tirapazamine was given in a single dose of 18 mg/m2 to 293 mg/m2 i.v. after irradiation. In a third trial, tirapazamine was administered without irradiation in single doses of 36 mg/m2 to 250 mg/m2, with an option for retreatment.

RESULTS

Subjects reported muscle cramping of varying degrees of severity on all three dose schedules. One patient experienced Grade 3 cramping and treatment was discontinued. The most frequent site of cramping were the lower extremities. Creatine phosphokinase (CPK) values were elevated in three patients with associated muscle soreness in one patient. MB (cardiac) isoenzymes were elevated in one patient with no evidence of cardiac muscle damage, and returned to baseline at drug completion. No consistent abnormalities in clinical laboratory values were found. Stretching of the muscle was most effective in relieving the cramping.

CONCLUSION

Muscle cramping has been the most frequently reported toxicity in Phase I studies of tirapazamine, though it does not appear to be dose limiting. Dose escalation on the three clinical trials continues. In vitro studies to investigate the cramping are ongoing.

MR imaging of patients with implanted drug infusion pumps

The influence of magnetic resonance (MR) imaging on the integrity and function of an implantable, programmable drug infusion pump and the distortion of the image by this device were tested. Six identical pumps were tested in magnetic fields of 1.5 T. Pump memory was not affected by the procedure. The pump rotor stalled (no infusion) as long as the device was within the magnetic field. Drug delivery resumed as programmed after the pump was removed from the field. No structural damage to the electrical or mechanical pump components was detected. The pump caused a circular image artifact (a signal dropout) within 8-10 cm of the device. The authors conclude that MR imaging is accurate if the area of interest is at least 10 cm from the pump, and that with awareness of temporary infusion cessation, it is safe to perform MR imaging in patients with this implanted pump.

Circadian-shaped infusions of floxuridine for progressive metastatic renal cell carcinoma

Sixty-eight unselected patients with progressive metastatic renal cell carcinoma (RCC) were treated between March 1985 and November 1988 with continuous infusion floxuridine (FUDR). Thirty-seven percent of these patients had previously received and failed systemic treatment. Using implantable pumps for automatic drug delivery, FUDR was continuously infused for 14 days at monthly intervals. The starting dose was 0.15 mg/kg/d (intravenous [IV]; n = 61) or 0.25 mg/kg/d (intraarterial [IA]; n = 7); IV doses were increased or decreased in increments of 0.025 mg/kg/d as permitted by toxicity. Diarrhea (with or without mild abdominal cramping) and nausea/vomiting limited the FUDR IV infusion, and hepatic function abnormalities limited FUDR IA infusion. The use of a circadian-modified infusion schedule permitted high FUDR doses to be safely given as compared with a constant rate infusion schedule. Of 63 patients assessable for response, 56 received systemic FUDR infusion. Four complete responses (CRs; 7.1%); and seven partial responses (PRs; 12.5%) were observed (objective response rate, CR plus PR, 19.6 +/- 5.1% [95% confidence limits] ). The median objective response duration was 10.8 months (range, 1 to 18 months; mean, 9.4 +/- 1.6). Four additional patients had minor tumor responses (MRs; 7.1%). In a subgroup of seven assessable patients receiving hepatic arterial FUDR, we observed one CR and three PRs (57.2 +/- 42.8%). Overall, objective response (CR plus PR) was seen in a quarter of assessable patients treated, 15 of 63, while only 15 of the 63 assessable patients (25.4%) have had objective tumor progression. The median follow-up time for all 68 patients was 28 months (range, 1 to 42), and their median survival duration is 15 months (range, 3 to 37 months). Continuous infusion FUDR is an effective outpatient treatment for progressive metastatic RCC, producing durable tumor response and causing little toxicity.

Determination of the therapeutic index of floxuridine by its circadian infusion pattern

To test if circadian timing of a drug is important for its toxicity and antitumor activity, we compared the circadian patterns observed with seven equal doses of floxuridine (FUDR) infused either at a variable rate or at a constant rate in female F344 rats. For the variable-rate infusion, the daily dose of FUDR was divided into four 6-hour portions of 68%, 15%, 2%, and 15% to achieve a quasisinusoidal pattern. Peak drug delivery occurred during one of six different times of day. At a dose level resulting in 50% overall mortality, lethal toxicity differed significantly, depending on the circadian stage of maximum drug delivery. Depending on the circadian stage of maximum drug flow, variable-rate infusions were more toxic than or as toxic as constant-rate infusion. FUDR lethality was lowest when constant-rate infusion was used or when variable-rate infusion peaked during the late activity-early rest span of the recipients. The circadian pattern of variable-rate infusion also determined the antitumor activity in tumor-bearing rats. At a therapeutic dose level and at identical dose intensity, the variable-rate-infusion pattern, with peak drug flow during the late activity-early rest span, resulted in significantly greater delay in tumor growth than was observed with either the constant-rate infusion or other variable-rate patterns. We conclude that the toxicity and antitumor activity of FUDR depend on the circadian timing of the infusion peak when the drug is given by variable-rate infusion. Since some of the circadian-shaped infusions studied are toxicologically and therapeutically inferior to constant-rate infusion, the circadian pattern and not the quasi-intermittency of circadian FUDR administration is primarily responsible for these pharmacodynamic differences.

Circadian-based infusional FUDR therapy

FUDR (5-fluoro-2'-deoxyuridine) is one of the few chemotherapeutic agents with activity against metastatic renal cell cancer. Diarrhea and dehydration with long-term, constant-rate intravenous infusion may be severe and life-threatening. This gastrointestinal toxicity can be reduced by altering the rate of the infusion so that most of the daily dose is given late in the day, and a minimal infusion rate is delivered in the early morning hours. This complex therapy can be automatically administered by the programmable, implantable Synchro-Med Infusion System. Using a circadian modification of infusion delivery, toxicity is diminished and the FUDR dose can be safely increased, which may result in greater anti-tumor activity. This paper describes Phase I studies with 54 patients who were treated with intravenous FUDR. It also discusses results of a Phase II study using circadian-modified intravenous delivery of FUDR in the treatment of 61 patients with renal cell cancer. It outlines the nursing implications for management of the implantable, programmable drug delivery system and addresses the nursing role in preventing, recognizing, and controlling FUDR-associated toxicities.

Circadian patterning of continuous floxuridine infusion reduces toxicity and allows higher dose intensity in patients with widespread cancer

Continuous long-term 5-fluoro-2'-deoxyuridine (floxuridine; FUDR) infusion frequently causes severe and dose-limiting gastrointestinal toxicity when administered at a constant rate at commonly prescribed dose levels. In preclinical studies, a circadian infusion pattern peaking late in the daily activity phase was better tolerated and had superior antitumor activity than a constant infusion against a transplanted tumor. Based upon these data and upon other chronobiological cytokinetic and pharmacologic considerations, we compared a circadian patterned variable rate infusion with a maximal flow rate in the late afternoon/early evening and minimum flow rate during the early morning hours to a constant rate infusion in 54 patients with widespread cancer. All FUDR infusions were administered using an implanted drug pump. In a pilot crossover study and a second randomized trial, patients with metastatic malignancies treated with equal dose intensities experienced less frequent and less severe diarrhea, nausea, and vomiting following variable rate infusion. In a third study, the dose intensity of variable rate infusion was escalated stepwise to determine the maximum-tolerated dose. Patients receiving time-modified FUDR infusion tolerated an average of 1.45-fold more drug per unit time while evincing minimal toxicity. FUDR infusion was found to have activity against progressive metastatic renal cell cancer (RCC). Increased dose intensity achieved by optimal circadian shaping may improve the therapeutic index of infusional FUDR and may help control malignancies that are refractory to conventional chemotherapy.

Dihydropyrimidine dehydrogenase activity in human blood mononuclear cells

Dihydropyrimidine dehydrogenase (DPD; EC 1.3.1.2) catalyzes the rate-limiting reaction in the catabolism of endogenous uracil and thymine and exogenous fluoropyrimidines. DPD activity was studied in human blood mononuclear cell supernatants utilizing a new and sensitive radiochromatographic assay. Total DPD activity showed a linear correlation with supernatant protein concentration. The affinity constants (Km) for NADPH and thymine were approximately 10 and 1 mumol/l, respectively. Maximal activity (Vmax) was observed at 0.25 mmol/l NADPH and 10 mumol/l thymine, respectively. DPD activity in normal individuals was 8.0 +/- (SD) 2.2 nmol/mg protein/h, and ranged from 4.4 to 12.3 nmol/mg/h (n = 25). This activity range was quite similar to values obtained in patients with metastatic solid tumors treated with fluorodeoxyuridine (FUdR; n = 33, p = 0.57). No correlation was found to exist between mononuclear leucocyte DPD activity and the observed toxicity of FUdR in the tested patients. A bimodal distribution of DPD activity was observed in the patients and in normal individuals. The entire study population tested could be divided into two groups with respect to DPD activity; one group with high (greater than 8 nmol/mg/h) activity and another with low (less than 8 nmol/mg/h) activity. The possibility that sex differences may have been responsible for this distribution of DPD activity could not be excluded. The findings of this study are relevant to the pharmacogenetics of fluoropyrimidines in humans.

Circadian rhythm and seasonal dependence in the toxicological response of mice to epirubicin

Compared to doxorubicin, equimolar epirubicin toxicity is reduced by about 50% by the epimerization of a hydrogen and hydroxyl group at the 4' position of the anthracycline sugar moiety. The circadian timing of doxorubicin administration markedly affects its lethal and sub-lethal bone marrow and gut toxicities in mice, as well as the severity of its clinical toxicity. We tested whether the timing of administration of equitoxic epirubicin doses similarly affected the toxicological response in female CD2F1 mice. A large and highly reproducible effect of the circadian stage of administration was documented with best drug tolerance occurring during the first half of the daily rest (light) span of the animals. In addition to this circadian rhythm, a significant seasonal effect was found with significantly fewer deaths occurring after epirubicin was given in the Summer, as compared to the Winter. Safest circadian timing for epirubicin is statistically significantly earlier in the day than for doxorubicin, while their seasonal patterns are quite similar.

Progressive metastatic renal cell carcinoma controlled by continuous 5-fluoro-2-deoxyuridine infusion

We treated 19 patients with progressive metastatic renal cell carcinoma with continuous infusion of 5-fluoro-2-deoxyuridine, 52 per cent of whom had previously received and failed chemotherapy. Implantable pumps were used for automatic drug delivery. 5-Fluoro-2-deoxyuridine was infused continuously for 14 days at monthly intervals. The starting dose was 0.15 mg. per kg. per day (intravenous) or 0.25 mg. per kg. per day (intra-arterial). Intravenous doses were increased or decreased in increments of 0.025 mg. per kg. per day as permitted by toxicity. Abdominal pain, diarrhea and mucositis limited the intravenous infusion, while malaise, anorexia and hepatic function abnormalities limited intra-arterial infusion. Of 18 evaluable patients we observed 1 complete, 4 partial (objective response rate 28 per cent) and 2 minor responses. The duration of response ranged from 2 to greater than 18 months. During a median follow up of 7.5 months (range 2 to 21 months) only 4 of the 18 patients had objective tumor progression. Over-all survival for the 19 patients was 94 per cent. Continuous infusion of 5-fluoro-2-deoxyuridine may be effective for the treatment of progressive renal cell carcinoma.

Methylene blue protects intestinal mucosa from free radical-mediated sublethal radiation damage

Susceptibility of the intestine to radiation damage is a primary reason for the failure of external beam radiation to cure intra-abdominal cancer. High-dose irradiation causes intestinal denudation, fluid loss, and resultant shock. Simple and effective methods for protecting the intestine from irradiation damage are not available. Many biological effects of ionizing irradiation are caused by free radical intermediates. We have previously reported that many of the toxicities of doxorubicin, a classic free radical generating anticancer agent, are blocked by methylene blue pretreatment. We have now found that pretreatment with methylene blue protects rats from intestinal damage, as measured histologically and by quantitative stool blood determinations. Whereas the exact mechanisms of this protection remain elusive, we believe this method of modulating the therapeutic index of ionizing radiation deserves additional preclinical and clinical study.

High-dose intensity, circadian-timed doxorubicin and cisplatin adjuvant chemotherapy for bladder cancer

Thirteen patients with transitional cell carcinoma of the bladder received monthly circadian-timed doxorubicin and cisplatin chemotherapy immediately after radical cystectomy. In five patients cancer had spread through the serosa of the bladder wall and/or into the perivesical fat (stage C). In eight patients cancer had spread to other pelvic tissues and pelvic lymph nodes (stage D1). Ten of these 13 patients showed no recurrence of disease after a median follow-up period of 3.5 years (range, 1 to greater than 5.5); these patients received no chemotherapy for a median duration of 3 years (range, 2-5). Two of the three patients who ultimately failed had local tumor recurrence which occurred much later than is the usual case (40 and 52 months). This circadian-timed two-drug regimen, given in full doses for nine courses as adjuvant treatment, delays and may prevent local and distant recurrence of stage C and D1 bladder cancer.

High-dose intensity systemic therapy of metastatic bladder cancer

Forty-three consecutively diagnosed patients with widely metastatic transitional cell carcinoma of the bladder (TCCB) were treated with a high-dose intensity, chronobiologically timed combination of doxorubicin and cisplatin, followed by Cytoxan (Mead Johnson Pharmaceuticals, Evansville, IN), 5-fluorouracil (5-FU), and cisplatin maintenance for up to 2 years. Fifty-seven percent of the 35 evaluable patients with widespread metastatic cancer responded objectively. Twenty-three percent had complete disappearance of all cancer. Median survival from first treatment for complete responders (CRs) was more than 2 years, and 1 year for partial responders (PRs). Three of the CRs were alive without evidence of cancer more than 2 years after stopping all therapy. High-dose intensity combination chemotherapy can induce durable CRs of widespread bladder cancer.

Cisplatin chronotherapy and disulfiram rescue reduce toxicity without interfering with anticancer activity: animal findings and preliminary clinical experiences

Cisplatin-induced mortality and nephrotoxicity are each predictably worse when the drug is given at certain points within the circadian schedule. Oral disulfiram protects rats from toxic effects at some circadian stages but not others. This manuever does not diminish the anticancer activity of cisplatin in these rats. Human beings given 2 g of oral disulfiram and high doses of cisplatin at the circadian stage associated with least cisplatin nephrotoxicity (prospectively determined potassium excretion acrophase) suffer little or no kidney damage. Disulfiram administration apparently does not interfere with the antineoplastic activity of cisplatin in humans. This is the first demonstration of the feasibility of assignment of treatment time according to a measure of the patient's 'internal clock' as assessed by pretreatment marker rhythmometry. It also establishes the feasibility of giving disulfiram to human beings.

Advanced transitional cell bladder cancer: a treatable disease

Although metastatic bladder cancer is difficult to treat effectively, chemotherapy combinations and schedules have emerged recently that can result in long-lasting complete responses in some patients. Response rates, response durations, and survival patterns of the entire patient population are, however, unsatisfactory. Whereas survival times of these patients following therapy with cisplatin alone or in combination with other drugs are not significantly different, complete response rates are higher and disease-free survival is longer when combinations are used. Higher dosages are associated with better response rates but also with substantial toxicity. Extensive local pretreatment or prior systemic chemotherapy reduces the likelihood of clinically meaningful disease response. Several adjuvant studies have demonstrated an advantage in length of disease-free survival for chemotherapy-treated patients when compared to those who are observed following operation. Metastatic transitional cell bladder cancer is a chemotherapeutically treatable malignancy. Locally advanced disease may be most effectively treated by aggressive surgery followed by cisplatin-based combination chemotherapy. The highest response rates and longest disease-free survivals are uniformly associated with aggressive and prolonged multidrug therapy.

Lack of antiemetic effect of high-dose metoclopramide

Sixteen of 26 patients given 51 courses of treatment of the doxorubicin and cisplatin combination with no antiemetic therapy suffered the same number of vomiting episodes and had the same duration of vomiting as did the remaining ten patients given 20 cycles of this chemotherapy plus the standard high-dose metoclopramide regimen. This antiemetic regimen caused significant side effects in one fifth of the patients receiving it.

Mandibular myelosarcoma (chloroma): primary oral manifestation of promyelocytic leukemia

The case of a 35-year-old female patient with primary mandibular manifestation of myelosarcoma (chloroma) is reported. The clinical course and diagnostic and therapeutic measures are described. Myelosarcomas are rare and are considered specific lesions of an acute myeloid leukemia. In addition to systemic leukemia therapy, myelosarcomas frequently have to be treated surgically or by irradiation because of their specific tumor localizations.

[Chemotherapy in pretreated Hodgkin's disease with lomustine, bleomycin, vinblastine and dexamethasone]

A combination of lomustine (120 mg/m2 day 1), bleomycin (15 mg day 1 and 22), vinblastine (6 mg/m2 day 1 and 22) and dexamethasone (3 mg/m2 day 1 up to 21) was used in 20 patients with Hodgkin's disease stage II B (n = 2), III B (n = 4) and IV B (n = 14). These patients had not responded to earlier standard chemotherapy or had had a relapse within one year. Treatment cycles were repeated six-weekly. Nine cases showed complete and six cases partial remission. No change was seen in two cases and progression occurred in three patients. The median time of remission was 10 months. Multiple extranodal involvement had a particularly unfavourable prognosis: only one out of five patients showed remission. Two out of 7 patients with progression during COPP and 3 out of 5 patients with progression during ABVD remitted completely, indicating a slight cross resistance only among the three combinations of chemotherapeutics. Treatment was well tolerated and can be done on an out-patient basis.

[Disease-specific renal failure in angioimmunoblastic lymphadenopathy - remission by high dose prednisolone. A case report (author's transl)]

The case of a 64 years old male with angioimmunoblastic lymphadenopathy (AIL) is reported, who developed disease specific infiltration of the kidneys with progressive destruction of renal parenchyma leading to high grade renal insufficiency. This unusual organ manifestation of AIL has not been previously reported. By treatment with high dose prednisolone and intense supportive therapy the patient underwent complete remission of AIL with preservation of the remaining renal function. Clinical, laboratory and immunological data are given as well as a light and electron microscopic evaluation of the renal involvement.

[Clinical expressions of plasmocytoma (author's transl)]

Multiple myeloma is the most frequent type of hemoblastic disorders including paraproteinemia. Most cases show a disseminated involvement; few patients have solitary lesions of the bones or connective tissues. Different localizations are the reason for the multiform clinical picture of the disease. The main symptoms result from neurological and dermatological involvement, less usual are gastrointestinal complaints. Fractures, neurological deficiencies, lack of antibodies and failure of the kidneys determine the course of plasmocytoma. Our case reports are demonstrating examples of the different clinical expressions.