Phase II study of SPI-77 (sterically stabilised liposomal cisplatin) in advanced non-small-cell lung cancer.

To determine the efficacy and tolerability of SPI-77 (sterically stabilised liposomal cisplatin) at three dose levels in patients with advanced non-small-cell lung cancer (NSCLC). Patients had Stage IIIB or IV NSCLC and were chemo-naïve, and Eastern Oncology Cooperative Group 0-2. The first cohort received SPI-77 at 100 mg m-2, the second 200 mg m-2 and the final cohort 260 mg m-2. Patients had also pharmacokinetics and analysis of leucocyte platinum (Pt)-DNA adducts performed. Twenty-six patients were treated, with 22 patients being evaluable for response. Only one response occurred at the 200 mg m-2 dose level for an overall response rate of 4.5% (7.1% at >or=200 mg m-2). No significant toxicity was noted including nephrotoxicity or ototoxicity aside from two patients with Grade 3 nausea. No routine antiemetics or hydration was used. The pharmacokinetic profile of SPI-77 was typical for a liposomally formulated drug, and the AUC appeared to be proportional to the dose of SPI-77. Plasma Pt levels and leucocyte DNA adduct levels did not appear to rise with successive doses. SPI-77 demonstrates only modest activity in patients with NSCLC.

The stability of ifosfamide in aqueous solution and its suitability for continuous 7-day infusion by ambulatory pump.

Dose fractionation is known to reduce the toxicity of ifosfamide and also results in an increased production of alkylating metabolites. Administration by slow infusion using the convenience of ambulatory pumps is therefore of interest. We used HPLC to investigate the stability of ifosfamide in aqueous solution (either alone, solution A, or mixed with mesna, solution B) under various conditions over a 9-day period. At both ambient temperature in daylight and 27 degrees C in a dark environment, there was no evidence of ifosfamide decay in either solution. However, at 37 degrees C in a dark environment, a fall was detected in both solutions, which at 9 days amounted to a loss of 7% of the amount of ifosfamide present at time zero. At 70 degrees C, levels of ifosfamide in both solutions fell within 72 h to markedly lower levels than controls, thus confirming that the methods used were indicative of stability. We conclude that ifosfamide, either alone or mixed with mesna, is stable for 9 days at temperatures up to 27 degrees C; even at 37 degrees C, the measured loss is small. The continuous infusion of ifosfamide over 7 days by ambulatory pump is now a practical proposition.

The effect of age on the pharmacokinetics of ifosfamide.

The effect of age on the pharmacokinetics of ifosfamide was studied in 20 patients with advanced non small cell lung cancer. A positive correlation was found between the elimination half-life of ifosfamide and age (r = 0.48, 0.05 less than P less than 0.01). This was due to an increase in volume of distribution with age (r = 0.66, 0.001 less than P less than 0.01). Total plasma clearance, renal clearance and non renal clearance did not change with age. Age did not affect the autoinduction of ifosfamide metabolism. Further studies are needed to demonstrate any adverse effects of ifosfamide in the elderly.

The stability of ifosfamide in aqueous solution and its suitability for continuous 7-day infusion by ambulatory pump.

Dose fractionation is known to reduce the toxicity of ifosfamide and also results in an increased production of alkylating metabolites. Administration by slow infusion using the convenience of ambulatory pumps is therefore of interest. We used HPLC to investigate the stability of ifosfamide in aqueous solution (either alone, solution A, or mixed with mesna, solution B) under various conditions over a 9-day period. At both ambient temperature in daylight and 27 degrees C in a dark environment, there was no evidence of ifosfamide decay in either solution. However, at 37 degrees C in a dark environment, a fall was detected in both solutions, which at 9 days amounted to a loss of 7% of the amount of ifosfamide present at time zero. At 70 degrees C, levels of ifosfamide in both solutions fell within 72 h to markedly lower levels than controls, thus confirming that the methods used were indicative of stability. We conclude that ifosfamide, either alone or mixed with mesna, is stable for 9 days at temperatures up to 27 degrees C; even at 37 degrees C, the measured loss is small. The continuous infusion of ifosfamide over 7 days by ambulatory pump is now a practical proposition.

Comparative pharmacokinetics of escalating doses of doxorubicin in patients with metastatic breast cancer.

Recombinant human granulocyte colony-stimulating factor (G-CSF) has been shown to reduce neutropenia following cytotoxic therapy, thereby enabling dose escalation to improve the response rate. It is important to know whether drug kinetics change as doses are increased. Doxorubicin was selected because of its broad spectrum of activity and its known efficacy in metastatic breast cancer. Doses of 75, 100, 125 and 150 mg/m2 were given to 11 patients with metastatic breast cancer by infusion over 30 min. Serum concentrations of parent drug and metabolites were determined during the first 48 h following the infusion by high-performance liquid chromatography (HPLC). The serum concentration vs time curve decayed as a triple exponential function in four patients and as a double exponential function in seven. A four-compartment model, one central and three peripheral, would predict concentrations to within 1 SE of the observed values. Doxorubicinol was the principal metabolite, and doxorubicinone and 7-deoxydoxorubicinone were clearly identified. There was a linear increase in the AUC infinity with dose. In addition, a small and transient increase in circulating levels of doxorubicinol and other important metabolites was observed 6 h following the administration of doxorubicin, which suggests the existence of an enterohepatic, or other, re-circulation mechanism. We conclude that in the dose range selected the kinetics of doxorubicin are linear and that the increase in toxicities seen with the higher doses of doxorubicin, following the second and third fortnightly administration, may be due to intracellular drug accumulation in tissues.

Comparative pharmacokinetics and alkylating activity of fractionated intravenous and oral ifosfamide in patients with bronchogenic carcinoma.

20 patients with advanced non-small cell lung cancer were treated with ifosfamide and mesna 1.5 g/m2 daily for 5 days; 10 received the drug by mouth and 10 i.v. Both schedules resulted in a reduction in the elimination half-life with an increased total and nonrenal clearance of ifosfamide over the 5-day period. Oral administration resulted in an unacceptably high incidence of encephalopathy(5/10) which was not seen in the i.v. group. In two patients this encephalopathy manifested itself as coma which lasted for 24 to 48 h but was fully reversible and in the other three cases as somnolence occurring for more than 50% of the patients' waking hours. Nadir blood counts and response rates were similar in both arms. The encephalopathy suggests that there are metabolic differences between the i.v. and oral routes and that a metabolite rather than the parent drug is responsible for this syndrome. In addition it was shown that the total and nonrenal clearance of the drug was significantly less when the drug was administered orally. None of the pharmacokinetic parameters either singly or in combination predicted for ifosfamide toxicity. No correlation between the creatinine clearance and ifosfamide renal clearance was demonstrated suggesting tubular reabsorption of the drug. In conclusion, ifosfamide cannot be given orally at the conventionally employed i.v. doses.

Prolongation of ifosfamide elimination half-life in obese patients due to altered drug distribution.

The pharmacokinetics of intravenous ifosfamide were determined in 16 patients with carcinoma of the bronchus. In all 25% (4) of these patients were obese (i.e. greater than 20% over their ideal body weight). The terminal elimination half-life (t1/2 beta) was found to be higher in the obese group than in the control group (6.36 h, range 5.77-7.45 h) vs 4.95 h, range 1.82-6.48 h) (P less than 0.05). This prolongation of the elimination half-life was due to an increased volume of distribution (Vd beta) in the obese group (42.81 1, range 35.49-51.90 l) vs 33.70 l range (17.76-50.62 l) (P less than 0.05). There was therefore no significant difference in total plasma clearance between the obese and normal groups. No correlation of ifosfamide plasma half-life was observed with total body weight (TBW) or ideal body weight (IBW). However, a significant positive correlation was observed between the percentage of IBW and plasma half-life. A strong positive correlation was observed between IBW and the plasma clearance of ifosfamide. The Vd beta correlated with both TBW and the percentage of IBW, but not with IBW itself. When Vd beta was normalised for IBW, there was a strong positive correlation with the percentage of IBW, suggesting that ifosfamide distribution into the TBW is higher than that into the IBW.

Clinical pharmacology of oral and intravenous 4-demethoxydaunorubicin.

The clinical pharmacology of 4-demethoxydaunorubicin (4-DMDNR) was studied in 28 patients with advanced breast cancer, using a sensitive reverse-phase HPLC technique. All patients had normal renal and hepatic function. The serum levels of 4-DMDNR after a single i.v. bolus injection followed a triple exponential decay curve (T 1/2 alpha = 9.6 min, T 1/2 beta = 3.2 h and T 1/2 gamma = 34.7 h) and conformed to a three-compartment model. Comparison of the area under the curve (AUC) and urinary excretion for the oral and i.v. routes suggests an oral bioavailability of approximately 24%. In patients treated with a schedule of weekly oral administration for periods of up to 12 months there was no significant alteration in either AUC or elimination half-life for the parent drug or its principal metabolite 13-OH4DMDNR. Moreover, there was no evidence of accumulation of the metabolite although measurable amounts were present 7 days after administration of 4-DMDNR.

A simple quantitative HPLC assay for ifosfamide in biological fluids.

A high performance liquid chromatography method is described for measuring Ifosfamide (I) in human serum. This involves solvent extraction, reverse phase HPLC and UV detection at 190 nm. Standard curves of peak height x detector sensitivity versus I concentration in serum were linear with a lower limit of detection of 100 ng/ml. Authentic 14C-labelled I cochromatographed with standard I and with I found in serum from treated patients. The concentration-time curves of I determined by both HPLC and gas chromatography were indistinguishable. We conclude that this method is suitable for determining I pharmacokinetics in biological specimens.

Bioavailability of ifosfamide in patients with bronchial carcinoma.

The pharmacokinetics of ifosfamide (I) were determined in ten patients with bronchogenic carcinoma. In seven patients, doses of 1 and 2 g (I) were given both as a bolus orally and later intravenously and were well tolerated. A further three patients received 5 g (I) as a single oral dose but in two this produced reversible CNS toxicity and severe vomiting. The area under the curve (AUC, microgram . h . l-1) for the 1-g dose was the same following oral and i.v. treatment and this was also true for the 2-g doses. There was a proportionate increase in the AUC for the 5-g oral dose, indicating 100% bioavailability at all three dose levels. We conclude that doses up to 2 g by mouth represent a well-tolerated alternative route of administration.

The pharmacokinetics of 7-hydroxymethotrexate following medium-dose methotrexate therapy.

An unambiguous and specific HPLC assay was used to determine the pharmacokinetics of 7-hydroxymethotrexate (7-OHMTX) following the administration of moderate-dose methotrexate (MTX) 100 mg X m-2 to 37 patients with advanced head and neck cancer. There was marked interpatient variation but patient exposure to 7-OHMTX was considerable. There was, however, no correlation between the amount of 7-OHMTX produced and either tumour response or patient toxicity.

Persistence of methylated bases in ribonucleic acid of syrian golden hamster liver after administration of dimethylnitrosamine.

1. Syrian golden hamster liver ribosomal RNA was isolated up to 96 h after administration of [14C]dimethylnitrosamine at 25 mg/kg or 2.5 mg/kg body weight. 2. The chemical alkyation products, 7-methylguanine, 3-methylcytosine, O6-methylguanosine and 1-methyladenosine, were measured after acidic or enzymic hydrolysis of the RNA to bases or mononucleosides followed by ion-exchange chromatography. 3. Between 7 and 96 h, the relative amounts of alkylation products did not change with time even though the absolute amounts fell by approx. 80% and 51% after the high and low doses respectively. 4. The results suggest that base specific excision repair does not exist for RNA alkylation products in this experimental system.

Accumulation of O6-methylguanine in non-target-tissue deoxyribonucleic acid during chronic administration of dimethylnitrosamine.

1. BD-IV rats were given labelled dimethylnitrosamine (2 mg/kg) by stomach tube on weekdays (Monday to Friday) for up to 24 weeks. The rats killed after 2, 4, 8, 16 and 24 weeks of treatment (72 h after the final dimethylnitrosamine gavage) and DNA was isolated from the pooled livers, kidneys and lungs. Purine bases were released from the DNA by mild acid hydrolysis and separated by Sephadex G-10 chromatography. 2. Throughout the experiment, the content of 7-methylguanine in liver DNA was approx. 16 times that in kidney and lung. The amount of this product increased in the DNA of all three tissues up to 16 weeks, but by 24 weeks had decreased by 20% in the liver and 46% in the other tissues. 3. O6-Methylguanine was not detected in liver DNA, but was easily measured in kidney and lung DNA after 4 weeks of dimethylnitrosamine administration. The amount of O6-methylguanine in kidney and lung DNA increased relative to that of 7-methylguanine, and by 24 weeks was 60% of the 7-methylguanine content in both tissues. 4. Incorporation of radioactive C1 breakdown products of dimethylnitrosamine into normal purines in DNA increased continuously in all three tissues. 5. The results are discussed with respect to the specific hepatocarcinogenic effect of chronic administration of dimethylnitrosamine and the possible contribution of increased DNA repair and DNA synthesis.

Effect of chronic administration of dimethylnitrosamine on the excision of O6-methylguanine from rat liver DNA.

Rats were exposed chronically to unlabelled N,N-dimethylnitrosamine (25 ppm in the drinking water) then given a single dose of N-[3H]methyl-N-nitrosourea (10 mg/kg body weight). The rates of loss of tritium-labeled 7-methylguanine, O6-methylguanine and 3-methyladenine from the liver DNA in control and dimethylnitrosamine-treated rats were found not to be significantly different. Thus, under the conditions used, inhibition of the O6-methylguanine excision repair system does not seem to be a factor in the induction of liver tumours by chronic DMN application.

Methylated purines in the deoxyribonucleic acid of various Syrian-golden-hamster tissues after administration of a hepatocarcinogenic dose of dimethylnitrosamine.

1. DNA was extracted from livers, kidneys and lungs of Syrian golden hamsters at various times (up to 96h) after injection of a hepatocarcinogenic dose of [14C]dimethylnitrosamine. Purine bases were released from the DNA by mild acid hydrolysis and separated by Sephadex G-10 chromatography. 2. At 7h after dimethylnitrosamine administration liver DNA was alkylated to the greatest extent, followed by that of lung and kidney, the values for which were 8 and 3% respectively of those for liver. 3. The O6-methylguanine/7-methylguanine ratios were initially the same in all three organs and in the liver DNA of rats under similar conditions of dose. 4. O6-Methylguanine was the most persistent alkylated purine in all three hamster tissues. There was evidence for excision of 7-methyl-guanine, the highest activity for this being present in the liver. 5. Detectable amounts of the minor products 3-methyladenine, 1-methyladenine, 3-methylguanine and 7-methyladenine were present in most hamster tissues, and their individual rates of loss from liver DNA were determined. 6. Ring-labelling of the normal purines in DNA was highest in the liver, followed closely by the lung (80% of that in liver) whereas the kidney had very low incorporation (3% of that in liver). 7. The results are discussed with respect to the hepatotoxicity of dimethylnitrosamine, the miscoding potential of the various alkylation products and the induction of liver tumours in hamsters.

Dimethylnitrosamine-induced inhibition of hepatic protein synthesis in vitro and the effect of pretreatment with cystamine or pregnenolone-16alpha-carbonitrile.

Hepatic protein synthesis was investigated using a postmitochondrial supernatant system derived from the livers of rats that were given injections of a single dose of dimethylnitrosamine (DMN), 30 mg/kg. The time course and extent of DMN-induced inhibition in vitro were identical to those reported for the incorporation of amino acids into liver proteins in vivo, maximum inhibition being about 70% at 5 hr. Addition of specific inhibitors of chain initiation (polyinosinic acid and aurin tricarboxylic acid) to the postmitochrondrial supernatant system from DMN-treated rats caused only a slight additional inhibition, indicating that DMN predominantly affects translation by a block of initiation. Treatment with cystamine prior to DMN administration completely abolished the depression of protein synthesis and reduced by more than 90% the methylation by [14C]DMN of purine bases in liver DNA. Pretreatment with pregnenolone-16alpha-carbonitrile stimulated protein synthesis in controls but had no preventive effect in DMN-treated rats and did not reduce the extent of DNA alkylation in vivo.