Potential efficacy of a delta 5-aminolevulinic acid bioadhesive gel formulation for the photodynamic treatment of lesions of the gastrointestinal tract in mice

A delta 5-aminolevulinic acid (ALA) bioadhesive gel has been developed and evaluated in an in-vivo mouse model for photodynamic treatment of gastric cancer or Barrett's oesophagus. Four gels were tested: noveon AA-1, keltrol T, lutrol and blanose. An initial in-vitro study of gel adhesion showed that noveon and keltrol had longer polyethylene transit times than lutrol and blanose. In-vivo assays indicated that protoporphyrin IX was synthesized by gastric mucosa when ALA-noveon and ALA-lutrol were used (preferable results for noveon). Keltrol was eliminated from the study after these investigations. Only ALA-noveon gel was retained for studies of the relationship between ALA dose and fluorescence. Fluorescence measurements in-vivo showed that ALA concentration and application time had an influence on protoporphyrin IX synthesis. Maximum intensity (2091 counts s-1) was found with 2 mg mL-1 ALA, and fluorescence intensities differed with application time, reaching 1805 counts s-1 after 240 min. ALA-noveon, showing good adhesion and enabling efficient diffusion of ALA at a pH < 6, was considered the best formulation for maintaining ALA stability.

In vitro and in vivo spectrofluorometry of a water-soluble meta-(tetrahydroxyphenyl)chlorin (m-THPC) derivative

The pharmacokinetics of a water-soluble derivative obtained from meta-(tetrahydroxyphenyl)chlorin (m-THPC) was evaluated in in vitro and in vivo studies. Cytoplasm fluorescence was measured in two cell models (L1210 and HT29) using a flow cytometer and a confocal microspectrofluorometer. Cells were incubated with the compound at several doses (0-150 micrograms ml-1 for flow cytometry) and for several time periods (0-6 h for microspectrofluorometry). For in vivo studies, nude mice were grafted with human adenocarcinoma 15 days before intraperitoneal injection of polyethylene glycol-m-THPC (PEG-m-THPC). Fluorescence was recorded through an optical fibre spectrofluorometer using the 660 nm peak for detection. In in vitro studies, the fluorescence was found to be proportional to the dose. Maximum fluorescence was recorded in L1210 cells earlier and more intensely than in HT29 cells (3 h at 202 +/- 14 counts s-1 and 5 h at 43 +/- 2.15 counts s-1 respectively). Concerning in vivo studies, maximum tumour fluorescence was observed 24 h after injection (3568 +/- 178 counts s-1). Selectivity was expressed by the calculated tumour-to-skin and tumour-to-muscle ratios. The time taken to observe the maximum ratios (2.95 +/- 0.16 for tumour-to-skin and 6.61 +/- 0.3 for tumour-to-muscle) was almost the same as the time taken to observe the maximum fluorescence in the tumour. Studies are in progress to correlate these results with photodynamic effects.

[Value and applications of pharmacogenetics in oncology and hematology]

Pharmacogenetics could be defined as the study of genetically controlled variations in drug response. Introduction of pharmacogenetics in hematology and oncology has been done recently. With recombinant DNA technology, like restriction analysis of genomic DNA, enzymatic amplification of DNA by the polymerase chain reaction and expression of cDNAs in cell cultures, this research area has been developed during the last 10 years. In hematology and oncology, we can integrate pharmacogenetics in 3 areas. First, the concept of genetic risk of cancer and the study of drug or carcinogen metabolizing enzymes that could modulate this risk, regarding the activity of some specific enzymes; second, the use of pharmacogenetics, related to the toxicity or efficacy of anticancer drugs, allowing the identification of key enzymes involved in the biotransformation of the drug and the study of molecular aspects involved in the regulation of the activity of the enzymes; third, the implication of the study of enzymatic activities in tumoral tissues as compared to non-tumoral tissues. The following differences between the 2 tissues can be subsequently used to increase the specificity of the anticancer drugs.

Clastogenic activity in the plasma of scleroderma patients: a biomarker of oxidative stress

BACKGROUND

Scleroderma patients exhibit increased chromosomal instability due to circulating clastogenic plasma factors (CF). Formation and action mechanisms of CF are mediated by superoxide. In addition, previous work detected inosine triphosphate (ITP) in the plasma of 2 patients, and the enzyme adenosine deaminase (ADA) was found to be increased.

OBJECTIVE

To study correlations between CF, ITP and ADA levels, CF and disease activity, as well as other biomarkers of oxidative stress.

METHODS

Clastogenic activity was evaluated by means of cytogenetic methods in 48 patients and 55 healthy subjects. ITP was detected by mass spectrometry and electrospray ionisation. ADA was measured with a colorimetric assay and malondialdehyde using the Yagi method.

RESULTS

Clastogenic activity was significantly increased in patients' plasma compared to controls. In 10 patients CF, ITP and ADA were studied simultaneously. All three parameters were increased in the 7 patients of subgroups 2 (skin and esophagus involvement) and 3 (skin plus multiple organ involvement). ITP was not detected in 2 patients of subgroup 1 (skin involvement only) with low ADA and CF values.

CONCLUSION

ITP, the deamination product of ATP, is one of the clastogenic and superoxide generating components of CF. The formation of this deamination product of ATP is probably related to the increase in ADA. CF are biomarkers of oxidative stress and can be used for evaluation of antioxidant treatments in scleroderma.

Drug resistance mechanisms in chronic lymphocytic leukemia

Peripheral blood samples from 18 patients with chronic lymphocytic leukemias (CLL) who were either untreated but who were later sensitive to chlorambucil (CLL S) or resistant to a combination containing doxorubicin, vincristine, cyclophosphamide and prednisone (CLL R) were studied for glutathione system, P-glycoprotein, PCNA and topoisomerase II expression. P-glycoprotein expression detected by an immunocytochemical technique using MRK 16 antibody was present at the same level in CLL S and CLL R. The percentage of cells positive for P-gp was below 5% in all samples tested. Topoisomerase IIalpha level was quantified by Western blot analysis. None of the 18 CLL samples had detectable topoisomerase IIalpha protein. In addition, 12 CLL were tested for PCNA staining and no samples had more than 1% of positive cells at immunocytochemical detection indicating that CLL cells were not engaged in the cell cycle. Some differences were found between CLL S and CLL R in the glutathione system. Glutathione concentration (GSH) and GST activity was the same in CLL S and CLL R. The glutathione-S-transferase (GST) isoenzyme profile was different in the two CLL groups. The mean GST-pi and GST-alpha quantitation were twice as high as in CLL R compared to CLL S, but this difference did not reach statistical significance because of large variations between CLL samples. A significant correlation was observed between GST-pi expression and GST activity using CDNB as the substrate. GST-mu was detected in only one of seven CLL before therapy and in six of 11 resistant to chemotherapy. No correlation was found between P-glycoprotein expression, GST activity and the different GST isoenzymes studied. These results suggest that the glutathione system could play a role in the resistance of anticancer agents in chronic lymphocytic leukemia. The role of the other drug resistance mechanisms (P-glycoprotein and topoisomerase IIalpha) seems to be of limited importance.

Therapeutic activity of CPT-11, a DNA-topoisomerase I inhibitor, against peripheral primitive neuroectodermal tumour and neuroblastoma xenografts

The anti-tumour activity of CPT-11, a topoisomerase I inhibitor, was evaluated in four human neural-crest-derived paediatric tumour xenografts; one peripheral primitive neuroectodermal tumour (pPNET) (SK-N-MC) and three neuroblastomas. Two models, SK-N-MC and IGR-N835, were established in athymic mice from a previously established in vitro cell line. Two new neuroblastoma xenograft models, IGR-NB3 and IGR-NB8, were derived from previously untreated non-metastatic neuroblastomas. They exhibited the classic histological features of immature neuroblastoma along with N-myc amplification, paradiploidy, chromosome 1p deletions and overexpression of the human mdr 1 gene. These tumour markers have been shown to be poor prognostic factors in children treated for neuroblastoma. CPT-11 was tested against advanced stage subcutaneous tumours. CPT-11 was administered i.v. using an intermittent (q4d x 3) and a daily x 5 schedule. The optimal dosage and schedule was 40 mg kg-1 daily for 5 days. At this highest non-toxic dose, CPT-11 induced 100% tumour-free survivors on day 121 in mice bearing the pPNET SK-N-MC xenograft. For the three neuroblastoma xenografts, 38-100% complete tumour regressions were observed with a tumour growth delay from 38 to 42 days, and anti-tumour activity was clearly sustained at a lower dosage (27 mg kg-1 day-1). The efficacy of five anti-cancer drugs commonly used in paediatric oncology or in clinical development was evaluated against SK-N-MC and IGR-N835. The sensitivity of these two xenografts to cyclophosphamide, thiotepa and cisplatin was of the same order of magnitude as that of CPT-11, but they were refractory to etoposide and taxol. In conclusion, CPT-11 demonstrated significant activity against pPNET and neuroblastoma xenografts. Further clinical development of CPT-11 in paediatric oncology is warranted.

Tumorigenicity of cerebellar primitive neuro-ectodermal tumors in athymic mice correlates with poor prognosis in children

The histogenesis of medulloblastoma, also described as a cerebellar primitive neuro-ectodermal tumor (PNET), remains controversial and unresolved. In addition, genetic markers which characterize cerebellar PNETs with poor prognosis in children have not been identified. Since xenografts can be valuable tools for better understanding the genetic events involved in cerebellar PNETs, small fragments of tumor samples from 17 children with newly diagnosed cerebellar PNETs were transplanted s.c. into female athymic Swiss mice. Eleven were non-metastatic and 6 were metastatic PNETs. Eight tumors (47%) were tumorigenic. Histological analysis showed 6 typical medulloblastomas, 1 PNET with melanin pigment and 1 PNET with a rhabdoid phenotype. Wide heterogeneity was observed in tumor growth, with a doubling time ranging from 8 to 81 days after the first passage. Tumorigenicity was correlated with the metastatic phenotype of the tumor (p < 0.001). All the patients but one with a tumorigenic tumor relapsed and died. The survival of patients with a non-tumorigenic PNET (67%) was significantly higher than that of patients with a tumorigenic PNET (13%) (p < 0.02). None of the xenografts or tumors from patients exhibited N-myc-gene alteration. Only one xenograft showed c-myc amplification, with an abnormal 15-kilobase fragment. None of the 17 tumors from patients showed amplification or c-myc-gene rearrangement. In conclusion, tumorigenicity of cerebellar PNETs strongly correlates both with the metastatic phenotype of the tumors and with the disease-free survival of the patients. In addition, genetic events other than c-myc-gene amplification might be involved in cerebellar PNETs with poor prognosis.

Pharmacokinetics and antitumor effects of mitoxantrone after intratumoral or intraarterial hepatic administration in rabbits

The intratumoral (i.t.) delivery of anticancer drugs aims at controlling tumor growth and thereby provides palliative treatment for liver neoplasms. Mitoxantrone is a good candidate for local or regional administration because (1) its metabolism is mainly hepatic, (2) it has a steep dose-response curve for multiple solid tumors, and (3) its fixation in tissues is sustained without vesicant effects after extravasation. We compared the tolerance, pharmacokinetics, and antitumor effects of mitoxantrone on hepatic VX2 tumors in rabbits treated with i.t. intraarterial hepatic (i.a.h.) or i.v. mitoxantrone, i.t. ethanol; or i.t. 0.9% NaCl and in control animals. Tumor growth rates (TGRs) were evaluated at 9 days after treatment. Myelosuppression was the limiting toxicity of i.v. mitoxantrone at 1.5 mg/kg (maximal tolerated dose, MTD), but neither i.t. nor i.a.h. administration led to hematologic toxicity at the same dose. The mitoxantrone retained in tumors after i.t. administration was seen as blue-stained areas of complete necrosis according to histologic analysis. Pharmacokinetic parameters showed a significantly decreased systemic exposure to the drug after both regional treatments, although the i.a.h. route appeared to have an edge over the i.t. route. TGRs were significantly reduced after i.t. mitoxantrone (81 +/- 62%), i.a.h. mitoxantrone (337 +/- 110%), and i.t. ethanol treatments (287 +/- 117%) as compared with control values (886 +/- 223%; p < 0.01). Treatment with i.v. mitoxantrone (816 +/- 132%) had no antitumor effect, nor did NaCl injections (868 +/- 116%). Mitoxantrone given i.t. induced the highest antitumor effects, resulting in a 3.5-fold reduction in TGRs as compared with i.a.h. mitoxantrone and i.t. ethanol treatments (p < 0.02). Treatment with i.t. mitoxantrone provided efficient antitumor therapy without producing major side effects. This method should be considered as palliative treatment for nonresectable liver tumors and other localized malignancies.

HepG2 human hepatocarcinoma cells: an experimental model for photosensitization by endogenous porphyrins

Endogenous protoporphyrin IX (PpIX) synthesis after delta-aminolaevulinic acid (ALA) administration occurs in cancer cells in vivo; PpIX, which has a short half-life, may thus constitute a good alternative to haematoporphyrin derivative (HPD) (or Photofrin). This study assesses the ability of the human hepatocarcinoma cell line HepG2 to synthesize PpIX in vitro from exogenous ALA, and compares ALA-induced toxicity and phototoxicity with the photodynamic therapy (PDT) effects of HPD on this cell line. ALA induced a dose-dependent dark toxicity, with 79% and 66% cell survival for 50 and 100 micrograms ml-1 ALA respectively after 3 h incubation; the same treatment, followed by laser irradiation (lambda = 632 nm, 25 J cm-2), induced a dose-dependent phototoxicity, with 54% and 19% cell survival 24 h after PDT. Whatever the incubation time with ALA, a 3 h delay before light exposure was found to be optimal to reach a maximum phototoxicity. HPD induced a slight dose-dependent toxicity in HepG2 cells and a dose- and time-dependent phototoxicity ten times greater than that of ALA-PpIX PDT. After 3 h incubation of 2.5 and 5 micrograms ml-1 HPD, followed by laser irradiation (lambda = 632 nm, 25 J cm-2), cell survival was 59% and 24% respectively at 24 h. Photoproducts induced by light irradiation of porphyrins absorb light in the red spectral region at longer wavelengths than the original porphyrins. The possible enhancement of PDT effects after HepG2 cell incubation with ALA or HPD was investigated by irradiating cells successively with red light (lambda = 632 nm) and light (lambda = 650 nm)(ABSTRACT TRUNCATED AT 250 WORDS)

Phase I-II and pharmacokinetic study of a new fotemustine schedule in advanced non-small cell lung cancer

Fotemustine, a new nitrosourea derivative has already demonstrated activity in non-small cell lung cancer (NSCLC). In order to improve its therapeutic index, we designed a protocol in which Fotemustine was delivered with dose escalation on 3 consecutive days as induction therapy followed by a 5-week rest period. Maintenance therapy consisted of 100 mg/m2 once every 3 weeks. Pharmacokinetic data were assessed during this Phase I-II study and reported here.

PATIENTS AND METHODS

Nineteen patients with metastatic (17) or locally advanced (2) NSCLC were included in the present study. Ten of those with metastatic disease had brain metastases and 15 had previously received chemotherapy. Fotemustine was given at 50 mg/m2 on day 1-2-3 (group 1: four patients), 75 mg/m2 on day 1-2-3 (group 2: 16 patients including two who had already received 50 mg/m2) and 100 mg/m2 on day 1-2-3 (group 3: one patient).

RESULTS

The maximal tolerated dose was 75 mg/m2 on day 1-2-3 (total cumulated dose 225 mg/m2). At this dose level, we observed 25% of Grade 3-4 neutropenia and 31% of Grade 3-4 thrombocytopenia. One patient died of pulmonary infection during aplasia. No other significant toxicity occurred. Of the 17 evaluable patients, one obtained a PR lasting 6 months in group 2 and 1 PR lasting 3 months in group 3. No significant difference was noted in the AUC between days 1, 2 or 3 in any of the seven patients in whom a pharmacokinetic study of Fotemustine was performed.

CONCLUSION

Administered on 3 consecutive days, Fotemustine seems to be less effective and more toxic than other schedules tested in NSCLC. Despite the quality of the two responses observed, this protocol has been discontinued and the standard administration on days 1 and 8 remains the schedule of choice in NSCLC.

Main drug-metabolizing enzyme systems in human non-Hodgkin's lymphomas sensitive or resistant to chemotherapy

Non-Hodgkin's lymphomas (NHL) are one of the most chemosensitive human malignancies. Complete response (CR) is often achieved, but many patients relapse and a second CR is difficult to obtain because of the development of chemoresistance. In an attempt to better understand the biology and the chemosensitivity of these lymphoid tumors, we assessed the main drug-metabolizing enzyme systems in normal lymphocytes, chemosensitive NHL and chemoresistant NHL. Cytochromes P-450 (1A1/A2, 2B1/B2, 2C8-10, 2E1, 3A4), epoxide hydrolase and glutathione S-transferases (GST-alpha, -mu, -pi) were assayed by immunoblotting. UDP-glucuronosyltransferase, beta-glucuronidase, sulfotransferase, sulfatase, GST activity, and glutathione (GSH) content, were determined by spectral assays. Results showed the absence of all probed cytochromes P-450 in normal lymphocytes and NHL cells tested. GST activity was significantly lower in chemoresistant NHL compared to normal lymphocytes. GST-alpha was not detected in either normal lymphocytes or NHL cells. GST-pi was the predominant isoenzyme, and GST-mu was not detected in chemosensitive NHL. GSH content was significantly lower in chemoresistant NHL compared to other lymphoid tissues tested. The conjugating enzymes UDP-glucuronosyltransferase and sulfatase were similar in either chemoresistant NHL compared to chemosensitive NHL. The activity of the hydrolytic enzyme beta-glucuronidase was lower in chemoresistant compared to chemosensitive NHL, whereas sulfatase was higher in sensitive NHL compared to normal lymphocytes. Epoxide hydrolase was not detected in either normal or NHL cells tested. In conclusion, these studies did not show any cytochrome P-450 in human lymphoid cells tested, but pointed out noteworthy differences for other enzyme systems tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase I and pharmacology study of flavone acetic acid administered two or three times weekly without alkalinization

Flavone acetic acid (FAA, NSC 347512) is a synthetic flavonoid compound with a unique form of preclinical antitumor activity, but its mechanism of action is still not known. In an attempt to exploit the remarkable preclinical activity of this compound in such a way as to allow its use as a clinically useful agent, we performed a phase I and pharmacology study with frequent administration and no hyperhydration or alkalinization. Sixteen patients (9 men, 7 women) were given FAA as 6-h i.v. infusions 2 or 3 times a week (10 and 6 patients, respectively), at doses ranging from 2.5 to 8.1 g/m2. A total of 130 doses were administered during this study. Sedation, arterial hypotension, vomiting and diarrhea were the predominant toxicities observed at the highest dose (8.1 g/m2. One patient developed severe but reversible multiple organ failure. No treatment-related deaths occurred. Pharmacokinetics was linear for the doses studied, with peak plasma levels ranging from 39 to 449 micrograms/ml and a mean terminal half-life of 3.1 h. No drug accumulation was observed with this frequent-administration schedule. No objective response was observed. Three FAA infusions per week at 8.1 g/m2 could be recommended as an optimal and tolerable schedule.

Stimulation of tumor growth in vitro and in vivo by suramin on the VX2 model

Suramin is an antitrypanosomal compound with confirmed efficacy against several human malignancies. It is generally assumed that its mechanism of action includes the interaction with different growth factors, unlike most of the anticancer drugs. Its anticancer activity has not been tested in vivo against squamous cell carcinoma. The purpose of this study was to assess the efficacy and toxicity of suramin in vivo and in vitro on the VX2 tumor model at therapeutic monitored plasma concentrations. We determined the pharmacokinetics of suramin in rabbits, and modelized its administration in order to obtain plasma concentrations between 150 and 300 micrograms/ml throughout the treatment course of 3 weeks. Under these conditions, antitumor effects of suramin were evaluated in vivo by comparing liver tumor involvement in suramin-treated and control rabbits. Liver involvement was quantified by image analysis and in vitro effects were also determined at the same concentrations. In vivo, suramin promoted liver tumor growth significantly (p < 0.05), compared to untreated controls. In vitro, suramin significantly stimulated tumor cell growth at concentrations above 200 micrograms/ml (p < 0.01). Suramin may have stimulatory effects on tumor growth in squamous cell carcinoma at relevant plasma drug concentrations. Caution should be taken in further trials in patients with squamous cell carcinomas.

Phase I and pharmacokinetic study of irinotecan (CPT-11) administered daily for three consecutive days every three weeks in patients with advanced solid tumors

BACKGROUND

We conducted a phase I and pharmacokinetic study to determine the maximum tolerable dose (MTD), toxicities, pharmacokinetic profile, and antitumor activity of Irinotecan (CPT-11) in patients with refractory solid malignancies.

PATIENTS AND METHODS

Forty-six patients were entered in this phase I study. CPT-11 was administered intravenously over 30 minutes for 3 consecutive days every 3 weeks. Dose levels ranged from 33 mg/m2/day to 115 mg/m2/day on days 1 through 3. The pharmacokinetics of total CPT-11 and its active metabolite SN-38 were assayed by HPLC.

RESULTS

The combination of leukopenia and diarrhea was dose-limiting toxicity at 115 mg/m2/day dose level, since 50% of the patients (5/10) experienced either grade 3-4 leukopenia, or diarrhea, or both. Leukopenia appeared to be a cumulative toxicity, with a global increase in its incidence and severity upon repeated administration of CPT-11. Other toxicities included nausea, vomiting, fatigue and alopecia. CPT-11 and active metabolite SN-38 pharmacokinetics were determined in 21 patients (29 courses). Both CPT-11 and SN-38 pharmacokinetics presented a high interpatient variability. CPT-11 mean maximum plasma concentrations reached 2034 ng/ml at the MTD (115 mg/m2). The terminal-phase half-life was 8.3 h and the mean residence time 10.2 h. The mean volume of distribution at steady state was 141 l/m2/h. CPT-11 rebound concentrations were observed in many courses at about 0.5 to 1 hour following the end of the i.v. infusion, which is suggestive of enterohepatic recycling. Total body clearance did not vary with increased dosage (mean = 14.3 l/h/m2), indicating linear pharmacokinetics within the dose range administered in this trial. The total area under the plasma concentration versus time curve (AUC) increased proportionally to the CPT-11 dose. Mean metabolite SN-38 peak levels reached 41 ng/ml at the MTD. A significant correlation was observed between CPT-11 area under the curve (AUC) and its corresponding metabolite SN-38 AUC (r = 0.52, p < 0.05). SN-38 rebound concentrations were observed in many courses at about 0.5 to 1 hour following the end of the i.v. infusion, which is suggestive of enterohepatic recycling. Mean 24-h urinary excretion of CPT-11 accounted for 10% of the administered dose by the third day, whereas SN-38 urinary excretion accounted for 0.18% of the CPT-11 dose. In this phase I trial, the hematological toxicity correlated with neither CPT-11 nor SN-38 AUC. Diarrhea grade correlated significantly with CPT-11 AUC. Two partial (breast adenocarcinoma and carcinoma of unknown primary) and 2 minor (hepatocarcinoma and pancreatic adenocarcinoma) responses were observed.

CONCLUSION

The MTD for CPT-11 administered in a 3 consecutive-days-every-3 weeks schedule in this patient population is 115 mg/m2/day. The recommended dose for phase II studies is 100 mg/m2/day.

Electrospray mass spectrometry for the characterization of the purity of natural and modified oligodeoxynucleotides

Electrospray ionization mass spectrometry is an accurate and sensitive analytical method to characterize the purity of oligodeoxynucleotides being tested for pharmacological studies. We report the preparation procedure ('desalting') of natural and modified oligodeoxynucleotides (ODNs) and their analysis by negative-ion electrospray mass spectrometry. We evaluate the sensitivity and the accuracy of the method for two antisense ODN sequences. Mass analysis of the 25-mer phosphorothioate can be performed to within 0.001% accuracy (standard error of 0.05 Da) for a sample concentration of 12 pmol/microL. In addition, the adduct ion and the failure sequence can be identified to characterize the antisense ODN.

Busulfan disposition and hepatic veno-occlusive disease in children undergoing bone marrow transplantation

Hepatic veno-occlusive disease (HVOD) is a frequent life-threatening toxicity in patients undergoing bone marrow transplantation (BMT) after the administration of a high-dose busulfan-containing regimen. Recent studies have shown that the morbidity and mortality of HVOD may be reduced in adults by pharmacologically guided dose adjustment of busulfan. We analyzed the pharmacodynamic relationship between busulfan disposition and HVOD in 61 children (median age, 5.9 years) with malignant disease. Busulfan, given at a dose ranging from 16 mg/kg to 600 mg/m2, was combined with one or two other alkylating agents (cyclophosphamide, melphalan, thiotepa). Only 3 patients received the standard busulfan/cyclophosphamide (BUCY) regimen. A total of 24 patients (40%) developed HVOD, which resolved in all cases. A pharmacokinetics study confirmed the previously reported wide interpatient variability in busulfan disposition but did not reveal any significant alteration in children with HVOD. The mean area under the concentration-time curve (AUC) after the first dose of busulfan was higher in patients with HVOD (6,811 +/- 2,943 ng h ml-1) than in patients without HVOD (5,760 +/- 1,891 ng h ml-1., P = 0.10). This difference reflects the higher dose of busulfan given to patients with HVOD. No toxic level could be defined and, moreover, none of the toxic levels identified in adults were relevant. The high incidence of HVOD in children given 600 mg/m2 busulfan may be linked to the use of more intensive than usual high-dose chemotherapy regimens and/or drug interactions. Before the prospective evaluation of busulfan dose adjustment in children, further studies are required to demonstrate firmly the existence of a pharmacodynamic relationship in terms of toxicity and allogeneic engraftment, especially when busulfan is combined with cyclophosphamide. The maximal tolerated and minimal effective AUCs in children undergoing BMT are likely to depend mainly upon the disease, the nature of the combined high-dose regimen, and the type of bone marrow transplant.

Phase I and pharmacologic studies of the camptothecin analog irinotecan administered every 3 weeks in cancer patients

PURPOSE

A phase I study was undertaken to determine the maximum-tolerated dose (MTD), principal toxicities, and pharmacokinetics of the novel topoisomerase I inhibitor irinotecan (CPT-11).

PATIENTS AND METHODS

Sixty-four patients meeting standard phase I eligibility criteria were included (24 women, 40 men; median age, 51 years; primary sites: colon, head and neck, lung, pleura; 60 of 64 had been previously treated). Pharmacokinetics was determined by high-performance liquid chromatography (HPLC).

RESULTS

One hundred ninety CPT-11 courses were administered as a 30-minute intravenous (IV) infusion every 3 weeks (100 to 750 mg/m2). Grade 3 to 4 nonhematologic toxicities included diarrhea (16%; three hospitalizations), nausea and vomiting (9%), asthenia (14%), alopecia (53%), elevation of hepatic transaminases (8%), and one case of skin toxicity. An acute cholinergic syndrome was observed during CPT-11 administration. Diarrhea appeared dose-limiting at 350 mg/m2, but this was circumvented by using a high-dose loperamide protocol that allowed dose escalation. Dose-dependent, reversible, noncumulative granulocytopenia was the dose-limiting toxicity (nadir, days 6 to 9; median recovery time, 5 days). Grade 3 to 4 anemia was observed in 9% of patients. One patient died during the study, 8 days after CPT-11 treatment. Two complete responses (cervix, 450 mg/m2; head and neck, 750 mg/m2) and six partial responses in fluorouracil (5-FU)-refractory colon cancer were observed (260 to 600 mg/m2). Pharmacokinetics of CPT-11 and active metabolite SN-38 were performed in 60 patients (94 courses). CPT-11 plasma disposition was bi- or triphasic, with a mean terminal half-life of 14.2 +/- 0.9 hours (mean +/- SEM). The mean volume of distribution (Vdss) was 157 +/- 8 L/m2, and total-body clearance was 15 +/- 1 L/m2/h. The CPT-11 area under the plasma concentration versus time curves (AUC) and SN-38 AUC increased linearly with dose. SN-38 plasma decay had an apparent half-life of 13.8 +/- 1.4 hours. Both CPT-11 and SN-38 AUCs correlated with nadir leukopenia and granulocytopenia, with grade 2 diarrhea, and with nausea and vomiting.

CONCLUSION

The MTD of CPT-11 administered as a 30-minute IV infusion every 3 weeks is 600 mg/m2, with granulocytopenia being dose-limiting. At 350 mg/m2, diarrhea appeared dose-limiting, but high-dose loperamide reduced this toxicity and allowed dose escalation. For safety reasons, the recommended dose is presently 350 mg/m2 every 3 weeks; more experience must be gained to establish the feasibility of a higher dose in large multicentric phase II studies. However, when careful monitoring of gastrointestinal toxicities is possible, a higher dose of 500 mg/m2 could be recommended in good-risk patients. The activity of this agent in 5-FU-refractory colorectal carcinoma makes it unique and mandates expedited phase II testing.

[Resistance associated with the glutathione system]

Several mechanisms of resistance (of bacteria to antibiotics, of plants to herbicides, of insects to insecticides, of cancer cells to cytotoxic agents...) have now been described. The most studied one is the glycoprotein coded by the mdr1 gene, which is involved in the efflux of numerous compounds of natural origin (anthracyclines, podophyllotoxins...) thus decreasing the intracellular concentration of such drugs. Nevertheless, many chemotherapeutic protocols include alkylating agents, such as cyclophosphamide and cisplatin, which are electrophilic species prone to react readily with the tripeptide glutathione, most often through glutathione-S-transferases. Therefore, it appears of major importance to evaluate the role of glutathione and that of the polymorphism of the glutathione-S-transferases, as prognostic factors in the response to chemotherapy.

Principal drug-metabolizing enzyme systems in L1210 leukemia sensitive or resistant to BCNU in vivo

1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU) resistance has been mostly studied in vitro. In an attempt to better understand BCNU resistance in the in vivo situation, we compared the principal drug-metabolizing enzyme systems in two L1210 leukemia lines, one sensitive and one resistant to BCNU (L1210/BCNU), passaged in vivo in mice. The following enzymes were assayed by immunoblotting: cytochromes P-450 (1A1/1A2, 2B1/2B2, 2C8-10, 2E1, 3A), epoxide hydrolase (EH) and glutathione S-transferase (GST-alpha, -mu and -pi). The following enzymes and cofactors were assayed fluorometrically or spectrophotometrically: 1-chloro-2-4 dinitrobenzene-GST (CDNB-GST), total glutathione (GSH), UDP-glucuronosyltransferase, beta-glucuronidase, sulfatase and sulfotransferase. Results showed that cytochrome P-450 1A1/1A2 was the only isoenzyme detected in both L1210 and L1210/BCNU. CDNB-GST activity was significantly higher in L1210/BCNU compared with L1210. The isoenzyme GST-alpha was more abundant in L1210/BCNU compared with L1210, whereas GST-pi was expressed less in the BCNU-resistant leukemia line. GST-mu was not detected in either L1210 leukemia lines. GSH levels were similar in the two L1210 lines. No significant difference was observed between the two leukemia lines for the conjugative enzymes UDP-glucuronosyltransferase and sulfotransferase, whereas their corresponding hydrolytic enzymes beta-glucuronidase and sulfatase were about two-fold lower in the BCNU-resistant leukemia line. Epoxide hydrolase was 1.3-fold higher in L1210/BCNU compared with L1210 and this level was about three-fold higher than in mouse liver. In conclusion, these studies showed the presence of cytochrome P-450 1A1/1A2 in the two L1210 leukemia lines studied, and indicated noteworthy differences between the two leukemia lines for many enzyme systems such as GST, beta-glucuronidase, sulfatase and epoxide hydrolase. These data are of importance to better understand the mechanisms of drug resistance to nitrosoureas in vivo.

Phase I and pharmacokinetic study of the camptothecin derivative irinotecan, administered on a weekly schedule in cancer patients

Irinotecan (CPT-11) is a novel water-soluble, semisynthetic derivative of camptothecin, with inhibitory effects on mammalian DNA topoisomerase I, high cytotoxic activity in vitro and anticancer activity in animal models. Fifty-nine patients, with cancer refractory to conventional therapy, were entered in this phase I study, using a weekly schedule administration. A total of 304 weekly doses were administered at dose levels ranging from 50 to 145 mg/m2 (30-90 min i.v. infusion). Leukoneutropenia and diarrhea were the dose-limiting toxicities and appeared to be dose related, reversible and noncumulative. However, interpatient variability of toxic effects was substantial. Prolongation of the infusion time from 30 min to 90 min appeared to decrease the diarrhea. Other toxicities included moderate emesis, asthenia, alopecia, abdominal pain, and anemia. CPT-11 plasma disposition was bi- or triphasic with a terminal half-life of 9.3 h. CPT-11 area under the plasma concentration versus time curves increased linearly with dose (r = 0.47, P < 0.01). The active metabolite area under the plasma concentration versus time curve correlated significantly with that of CPT-11, but not with that of CPT-11 dose. Both CPT-11 and 7-ethyl-10-hydroxycamptothecin areas under the plasma concentration versus time curve correlated significantly with leukoneutropenia and diarrhea. One partial and 4 minor responses were observed at dose levels of 130 and 145 mg/m2. Using this weekly schedule, recommended doses for phase II studies are 100 mg/m2 in high risk patients and 115 mg/m2 in others.

Verapamil-reversing concentrations induce blood flow changes that could counteract in vivo the MDR-1-modulating effects

BACKGROUND

Intraarterial hepatic (IAH) administration of verapamil should achieve mdr-1-reversing concentrations with reduced cardiac toxicity. The authors have explored the tolerance of its IAH administration and its effects on doxorubicin pharmacodymamics.

METHODS

Verapamil was given to rabbits by intravenous or IAH administration, and its effects on heart rates were compared. Doxorubicin then was given intravenously either with IAH verapamil or with an IAH control perfusion, and tumor and liver drug concentrations were determined. Hepatic blood flow changes were studied by the administration of 99mTc-albumin macroaggregates (99mTc-MAA) under verapamil IAH perfusions.

RESULTS

Compared with the intravenous route, IAH administration of verapamil was not toxic, and cardiac effects were reduced significantly. Its effect on doxorubicin distribution was detrimental, because the tumor-liver doxorubicin concentration ratios were lower in the verapamil group (0.23 vs. 3.37; P < 0.05). Tumor doxorubicin concentrations were lower when verapamil was coinfused (43 vs. 573 ng/100 mg tissue; P < 0.05). In normal liver tissue, increased amounts of doxorubicin and metabolites were observed. The verapamil IAH perfusions with 99mTc-MAA confirmed a differential action on tumor and normal vessels; the distribution of radionuclide was diverted away from the tumor bed significantly when verapamil was administered (tumor-to-liver ratio of 25.3 control rabbits vs. 5.99 rabbits who received verapamil; P < 0.05).

CONCLUSIONS

Reversing the concentrations of verapamil provoked changes in the distribution of the liver blood flow. The hemodynamic effects of verapamil regional perfusions could counteract in vivo its potential mdr-1-reversing properties.

Methods for the analysis of the new vinca alkaloid derivative, S 12363, in plasma by high-performance liquid chromatography with fluorescence detection

Two sensitive analytical methods for the analysis of S 12363 in plasma are described. A highly sensitive procedure for human and dog plasma using cyanopropyl solid-phase extraction with ion pairing chromatography and fluorescence detection, has a limit of quantification of 0.1 ng ml-1. The technique has an overall precision and accuracy of 4.8 and 5.4% respectively over the concentration range 0.1-20 ng ml-1. A second, less sensitive, assay specifically adapted for rodent plasma, uses benzene sulphonyl cation-exchange solid-phase extraction followed by reversed-phase chromatography, with post-column fluorescence enhancement. This method has a limit of quantitation of 1.0 ng ml-1, with overall accuracy and precision of 7.2 and 11.6% respectively, over the concentration range 1.0-20.0 ng ml-1. Both assays have been successfully applied to dog and mouse toxicokinetic studies.

Thymidylate synthase activity, folates, and glutathione system in head and neck carcinoma and adjacent tissues

BACKGROUND

Head and neck squamous cell carcinomas (HNSCC) present variable aggressiveness and chemosensitivity. Because the glutathione (GSH) system and thymidylate synthase (TS) are involved in the resistance to the main drugs used in HNSCC (cisplatin and 5-FU), we studied these systems in tumors and normal mucosae.

METHODS

Tumor samples and normal adjacent mucosae were collected from 37 untreated HNSCC patients. GSH and glutathione S-transferase (GST) activity were assayed by spectrophotometry, whereas TS activity and folates were determined by radioassays.

RESULTS

Mean GSH levels were higher in tumors (15.2 +/- 8.2 nmol/mg protein) than in mucosae (8.3 +/- 4.1 nmol/mg protein) (p = 0.005, paired t test). GST activity was also higher in tumors (394 +/- 194 nmol/min/mg protein) than in mucosae (261 +/- 132 nmol/min/mg protein) (p = 0.0003). TS activity was markedly higher in tumors (9.2 +/- 21.5 pmol/min/mg protein) compared to that of mucosae (0.9 +/- 1.2 pmol/min/mg protein) (p = 0.0001). Folate levels in tumors and mucosae were similar (1.2 +/- 1.1 and 0.8 +/- 0.9 pmol/mg protein, respectively; p = 0.1, NS). In relation to clinical stage and tumor size, a statistical difference was found in GSH and GST values between tumors and mucosae for stage IV and T3/T4. The increase in tumor TS compared to that of mucosae was significant for all clinical stages, tumor sizes, and nodal involvement.

CONCLUSIONS

These data enhance our understanding of the enzymatic systems involved in cisplatin and 5-fluorouracil (5-FU) resistance in HNSCC and normal mucosae and may help to elucidate tumor behavior and interpatient differences in drug sensitivity.