[13N]cisplatin PET to assess pharmacokinetics of intra-arterial versus intravenous chemotherapy for malignant brain tumors

The biodistribution, blood clearance, and in vivo transformation of cisplatin (cisdiaminedichloroplatinum, DDP) were studied in rats using 13N-labeled and unlabeled DDP. Following the i.v. injection of [13N]DDP, virtually no 13N activity was detected in brain tissue, and no measurable amount of the 13N label was displaced from [13N]DDP. Based on these results, [13N]DDP/positron emission tomographic (PET) scans were performed in two glioblastoma patients undergoing Phase II intra-arterial (i.a.) DDP chemotherapy: [13N]DDP was infused i.v. over 13-15 min, during which time serial PET scans were obtained. One hour later, [13N]DDP mixed with cold DDP (100 mg/m2 therapeutic dose) was infused at the same rate i.a., and a second sequence of PET scans was acquired. The pharmacologic advantage of i.a. administration was calculated as the ratio of integrated tumor/brain count ratios for the i.a. and i.v. studies. Our preliminary results demonstrate the feasibility of quantifying the pharmacologic advantage of i.a. DDP chemotherapy in individual brain tumor patients using [13N]DDP and PET.

Evaluation of the pharmacological benefit and determination of the influencing factors of intraarterial cis-diamminedichloroplatinum administration in patients with uterine cervical cancer

cis-Diamminedichloroplatinum (100 mg/m2) was administered to the same patients (n = 9) with advanced uterine cervical tumors, via i.v. and intraarterial (i.a.) (bilateral hypogastric arteries) routes. Measurement of plasma pharmacokinetic parameters enabled us to show up areas under the curve (AUC) of free cis-diamminedichloroplatinum versus time significantly (P less than 0.01) lower after i.a. injection (mean value, 3.9 mg.h/liter) than after i.v. injection (mean value, 5 mg.h/liter). However, the increase in intratumoral concentrations after i.a. administration was only at the limit of statistical significance (P = 0.05). Consequently, the benefit of local i.a. administration, evaluated according to the method of Collins, was small (1.2-2.3). An explanation of the phenomena observed can be given using the generalized compartmental model of Collins. We have demonstrated that the parameters of this model can be entirely calculated by taking into account both the i.v. and i.a. pharmacokinetic measurements. Calculations from experimental data of the model parameters, clearances of the body (ClB), and exchange rate between the site of administration and the rest of the body (Q) were in accordance with the physiological values. On the basis of the parameter values, it was confirmed that the low benefit of i.a. administration was due to the fast blood exchange between the injection site and the rest of the body and the probable cis-diamminedichloroplatinum binding on healthy tissues irrigated by the hypogastric artery.

[Pharmacokinetics of high-dose cisplatin administration (relationship between pharmacokinetics and administration schedule)]

Three cases of urogenital malignancy were treated with 80-120/m2 of cisplatin by a 0.5-hour (rapid) or 4-hour (slow) infusion. Each patient received three courses of repeated chemotherapy. The kinetics of total platinum was measured up to 48 hours in the blood and urine. The blood peak concentrations were achieved 6.0 micrograms/ml by rapid infusion, 2.0 micrograms/ml by slow infusion. The time dependent urinary excretion rate against total administered dose was 40% in 60 min. by rapid infusion, 20% in 16 hours by slow infusion. The volume of distribution correlated with infusion time. Rapid infusion way of cisplatin could be better to treat the patient with bulky tumor mass or patients with uroepithelial cancer like CIS, because a higher blood and urine concentration can be obtained than by slow infusion.

Continuous infusion of high-dose cisplatin in children: pharmacokinetics of free and total platinum

A pharmacokinetic study was carried out in two infants and two (older) children with high-dose cisplatin (CP) (40 mg/m2/day) by 5-day continuous infusion. Following interruption of the infusion, the decrease in total plasma platinum was biphasic, with a terminal half-life of 155.5-418 h. During administration the urinary concentrations were between 7.66 and 15.2 mg/l. Thirty to thirty five per cent of the administered dose was eliminated within 48 h of discontinuing infusion. Free platinum (FP) levels declined in a biphasic manner, with a mean (+/- S.E.) elimination half-life of 81.25 (+/- 34.9) h. FP was still detectable in the plasma 10 days after the end of infusion with levels above 0.010 micrograms/ml. FP availability, measured as the area under the curves (AUC) of the FP concentration--up to 2 h after ending the infusion--were 768 (+/- 326) micrograms.min/ml. Inter- or intra-individual differences in AUC values were not observed.

[Measuring cis-dichlorodiamino platinum(II) concentrations in human blood and mouth mucosa]

Using the method of atomic absorption spectroscopy, platinum (DDP) concentrations were determined in tissue samples and plasma from 10 patients who suffered from a squamous cell carcinoma and were receiving cis-platinum. The drug was administered by a rapid infusion (60 mg/m2). Tissue samples and plasma were collected 5 h after infusion. Platinum concentrations found in squamous cells of the oral cavity varied from 3 to 20 micrograms/g with a median concentration of 7.5 micrograms/g. The corresponding plasma concentrations were 1.5-2.5 micrograms/ml. The data suggest that within 5 h after infusion an enrichment of cis-platinum takes place in human tissue.

DNA cross-linking following exposure to cis-platinum in primary and serially passaged cultured cells derived from two murine fibrosarcomas

We compared the kinetics of the repair of total (ISC plus DPC) cross-links and of proteinase-resistant (ISC) cross-links in cultured cells derived from two murine fibrosarcoma tumors, FSA and NFSA, after treatment with cis-platinum (cis-DDP), using a modification of the alkaline elution technique. The two tumors had previously been characterized for their response to cis-DDP in vivo; FSA cells gradually removed cross-links from their genome, whereas the NFSA cells showed no capacity to repair these lesions. The aim of the present study was to establish whether treatment of cells from these same two tumors grown under controlled culture conditions would affect either the nature of the lesions induced by cis-DDP or the kinetics of repair of these lesions when compared with tumors treated with cis-DDP in vivo. The culture conditions represent two situations: in the first, the cells in culture approximated the proportion of tumor and normal host cells present in vivo, and in the second, the normal host cells had been eliminated by subculturing to produce cultures composed entirely of tumor cells. All cells were exposed to cis-DDP (either 10 or 20 micrograms/ml) for 1 h. The relative amounts of total cis-DDP-induced DNA crosslinks and of ISCs were then determined at various times after treatment. The results show that there was little difference in the behavior of these cultured cells compared to the in vivo response of the tumor from which they were derived. For FSA, each cell culture exhibited a capacity to repair DNA cross-links comparable to that of the tumor in vivo. For NFSA, the passaged cells again paralleled the behavior of that tumor in vivo, although in this case by showing no measurable capacity to repair cross-links. The absence of a significant repair response in the NFSA tumor therefore appears to be an intrinsic characteristic of these tumor cells.

[Combination effects of cis-dichlorodiammineplatinum (II) and sodium thiosulfate on renal dysfunction]

Forty-five patients with lung carcinoma were randomized to receive CDDP alone (STS (-) group) or combination of sodium thiosulfate (STS (+) group). Among the 45 patients, 42 had primary lung carcinoma and four had metastatic lung carcinoma. The combination of CDDP and STS infusion was performed in twenty-three patients and CDDP alone in 22 patients. The patients given STS were evaluated for renal function and pharmacokinetics. Urinary excretion of beta 2 microglobulin (BMG) and urinary concentration of N-acetyl-beta-D-glucosaminide (NAG), which reflect the function of the proximal tubules, were almost normal in the STS (+) group, but abnormally high in the STS (-) group. For serum BMG, BUN, creatinine, and 24-h creatinine clearance, which reflect glomerular function, no significant differences were found between the two groups. Urinary platinum excretion over 24 h was 29% in the STS (+) group and 21% in the STS (-) group. Total concentration of serum platinum after 24-h administration of CDDP was 2.1 micrograms/ml in the STS (+) group and 2.4 micrograms/ml in the STS (-) group. This study indicated that the combination of CDDP and STS promotes urinary excretion of CDDP, and rescues the dysfunction of the proximal tubules.

[The pharmacokinetics of cisplatin and its influence on renal functions based on different infusion methods]

The pharmacokinetics of cisplatin, together with its renal toxicity in relation to different infusion methods were examined. The subjects were 21 in-patients suffering from pulmonary carcinoma treated by anti-neoplastic agents including cisplatin. The patients included 12 given a 5-division dosage, 5 cases given 24-hour continuous infusion, 6 given 12-hour continuous infusion, and 7 given 6-hour continuous infusion. Cisplatin was determined as the concentrations of Pt in plasma and non-protein-bound Pt. Also, as indices of renal function, NAG in urine together with beta 2-microglobulin were examined. No substantial difference could be found in Pt concentration in plasma upon completion of the respective infusion methods. A dual-phase attenuation curve was obtained after the completion of infusion and the half-life period of the beta-phase was around 200 hours. With respect to non-protein-bound Pt concentrations, the 5-division dosage showed the highest value, which was considered to be a temporary phenomenon, while with continuous infusion, the shorter the infusion period, the higher the value became. With respect to the amount of NAG excreted in urine, 12-and 6-hour continuous infusion showed the higher value in comparison with the others in terms of the maximum value and the total amount. With regard to beta 2-microglobulin, 6-hour continuous infusion showed the highest value. The above results therefore suggest that in continuous infusion, the shorter the infusion period the greater the degree of renal tubule injury, and that particularly, 6-hour continuous infusion will possibly cause dysfunction of the renal tubules.

Pharmacokinetics and toxicity of intraperitoneal cisplatin combined with regional hyperthermia

Hyperthermia (HT) potentiates in vitro cytotoxicity of cisplatin, providing a rationale for HT enhancement of cisplatin effect in vivo. In this study, regional abdominal HT was combined with intraperitoneal (IP) cisplatin in canines to characterize temperature distributions, as well as pharmacokinetics and toxicity of IP cisplatin with and without HT. Cisplatin (65 mg/m2) in normal saline was administered IP with a two-hour dwell time in ten Beagle dogs. Five of the ten dogs were randomly selected to receive concurrent regional microwave-producing HT at approximately 41.5 degrees C (IP) for a 60-minute period. Systemic temperatures in heated animals ranged from 37 degrees C to 40 degrees C; IP temperatures ranged from 39 degrees C to 44 degrees C. Initial IP temperatures ranged from 39 degrees C to 44 degrees C. Initial IP cisplatin concentrations were ten to 22 times greater than serum levels; the IP drug half-lives were 133 +/- 9 minutes and 68 +/- 15 minutes in heated and unheated dogs, respectively (P less than .001). Total concentrations of serum and urine cisplatin did not differ between the heated and unheated controls. The area under the concentration v time curve for free, ultrafilterable cisplatin in serum in units of percent minutes was 40 +/- 8 in heated and 60 +/- 7 in unheated controls (P = .006). Except for transient nausea and vomiting, no evidence of serious toxicity was observed in serum chemistries or histopathologic sections at 21 days post-treatment. Experiments involving in vitro incubation of cisplatin in normal saline were performed as a function of saline temperature; these showed that the amount of reactive cisplatin metabolites formed increased linearly with temperature by approximately 30% from 38 degrees C to 44 degrees C. This study supports the hypothesis that, with IP temperature elevation, there is an increased rate of generation and retention of reactive metabolites of cisplatin in the peritoneal cavity relative to unheated controls. In spite of these differences in pharmacokinetics, no significant toxicity was encountered. This study provides a model for treatment of IP malignancy such as ovarian carcinoma with IP cisplatin and regional HT.

Influence of frusemide on cis-dichlorodiammineplatinum (II) pharmaco-kinetics

Cis-dichlorodiammineplatinum (CDDP) pharmacokinetics were evaluated in eighteen patients with cancer who received 80 mg/m2 CDDP as a 20 min infusion. One hour before, 10 of them had 20 mg/m2 frusemide. Fifteen blood samples and fifteen urine samples were collected over the 5 hours following the infusion of CDDP. Platinum was assayed by flameless atomic absorption. The data did not detect any difference between patients with or without frusemide for the following platinum parameters: plasma concentration, urinary concentration, cumulative urinary excretion, renal clearance. These results suggest that frusemide has no influence upon cisplatin (CDDP) pharmacokinetics and if it protects the kidneys, it is not via kinetic modifications.

The pharmacology of hepatic regional administration of cisplatin in a rabbit model

The pharmacology of hepatic regional administration of CisplatinR (DDP) was examined in a rabbit model. Routes and modes of administration were: IV, hepatic arterial infusion (HAI), HAI with stopflow, HAI with microembolic material [collagen for embolization (CFE)], and portal vein (PV). DDP was rapidly administered, blood samples were drawn over 45 minutes, and hepatic tissue was obtained. Filterable plasma DDP levels were measured by HPLC. Hepatic DDP levels were determined by atomic absorption spectroscopy. All modes of regional administration yielded significantly higher hepatic DDP levels when compared to tissue levels following IV administration. Only the PV and HACFE routes resulted in significantly less systemic drug exposure (AUC) when compared to IV administration. These data indicate a relative pharmacologic advantage of 1.8 for HAI, 3.4 for PV, 1.8 for HAI stopflow, and 4.3 for HACFE compared to IV DDP administration. This pre-clinical study demonstrates substantial pharmacologic advantage for PV and HACFE routes of DDP administration and suggests that clinical trials based on this information be considered.

Effects of doxorubicin and cisplatin on multicellular tumor spheroids from human lung cancer

We tested the sensitivity to doxorubicin (DXR) and cisplatin (DDP) of multicellular tumor spheroids (MTS) developed from 2 human lung cancer cell lines; PC-10 squamous cell carcinoma and PC-6 small cell carcinoma. DDP was able to maintain its efficacy in MTS: PC-10 MTS were only 3-fold more resistant to DDP than in monolayer and in PC-6 cells DDP induced cell lethality was essentially unchanged irrespective of cells being in a monolayer or MTS. Atomic absorption spectrometry revealed that DDP uptake was essentially identical, irrespective of cells being in monolayer or MTS. DDP's efficient cell kill effects in MTS seems to be explained by its good penetration into the MTS core. In contrast to DDP, these 2 types of cells responded differently to DXR. Thus, PC-10 MTS became progressively more resistant to DXR when their size increased, whereas the susceptibility of PC-6 MTS tended to increase when the MTS grew larger. Fluorescent microscopic study revealed that prominent DXR fluorescence was observed only at the outer layer of PC-10 MTS. In PC-6 MTS, however, DXR fluorescence was diffusely seen in the entire MTS at low concentrations; nevertheless, owing to PC-6 cells' high sensitivity DXR was able to exert cell lethality. The differences in distribution of DXR fluorescence between PC-10 and PC-6 MTS were corroborated by flow cytometric analysis.

A modified pharmacokinetic model for platinum disposition in ovarian cancer patients receiving cisplatin

We have fitted a first-order multicompartment pharmacokinetic model to plasma platinum concentrations measured in nine ovarian cancer patients who received intravenous infusions of cisplatin for 6 h. The time-course of ultrafilterable plasma platinum was similar in all patients studied, and was fitted by a single compartment within the limits of experimental detection. However, the time-course of protein-bound platinum showed marked differences between patients, the differences being explained by distribution to two peripheral compartments. The wide inter-patient variation observed in protein-bound plasma platinum concentrations supports the view that pharmacokinetic modelling should be carried out separately for each patient, since averaging plasma concentrations would have obscured some individual pharmacokinetic characteristics.

Comparative intraperitoneal pharmacokinetics of three platinum analogues

The pharmakokinetic profiles of intraperitoneally infused platinum analogues were determined in 13 women exhibiting minimal residual disease following surgery and systemic chemotherapy for epithelial ovarian cancer or fallopian tube carcinoma by following the disposition of tracer doses of 195mPt radiolabel. Six patients received iproplatin, four were given cisplatin and three received carboplatin. The present data demonstrate no difference in the disposition of total platinum between these three analogues, but differences in the kinetics of free platinum may exist.