Ability of cyclophosphamide in the absence of cross-linking activity to exert the immunomodulatory effect required for the cure of mice bearing a large MOPC-315 tumor

We have previously shown that mice bearing a late-stage, large primary MOPC-315 plasmacytoma and extensive metastases can be cured by a low dose of the bifunctional alkylating drug, cyclophosphamide (BiCY) (J.C.D. Hengst et al., Cancer Res., 40: 2135-2141, 1980). Here we show that therapy with the monofunctional form of cyclophosphamide (MoCY) can also cure such mice. However, a dose of at least 150 mg of MoCY per kg is required to approximate the curative effectiveness of the lowest curative dose of BiCY, i.e., 15 mg/kg. This need for a 10-fold higher dose of MoCY is due, at least in part, to the 10-fold lower direct tumoricidal and/or tumoristatic activity of MoCY compared to BiCY. Consequently, a 10-fold higher dose of MoCY is required to directly reduce the tumor burden to the level reduced by 15 mg of BiCY per kg. Other than dose, the therapy of the mice with 150 mg of MoCY per kg was similar in its essential features to that shown previously for therapy with 15 mg of BiCY per kg (J.C.D. Hengst et al., Cancer Res., 40: 2135-2141, 1980; J.C.D. Hengst et al., Cancer Res., 41:2163-2167, 1981; Q-W. Ye et al., Cancer Immunol. Immunother., 16:162-169, 1984; Q-W. Ye and M.B. Mokyr, Cancer Res., 44: 3873-3879, 1984; M.B. Mokyr and S. Dray, Cancer Res., 43: 3112-3119, 1983), namely: (a) the drug does not directly eradicate all tumor cells; (b) host T-cell-dependent antitumor immunity is also required for the curative effect; (c) the therapy of tumor bearers leads to the rapid appearance of an augmented antitumor immune potential in their hitherto immunosuppressed spleen; and (d) the cured mice are resistant to a subsequent challenge with at least 300-fold the minimal lethal tumor dose. Thus, cross-linking is not an essential property for the immunomodulatory activity of BiCY nor for its direct antitumor effect. However, in the presence of cross-linking activity, a much lower dose of drug is effective.     

Residue levels of hexachlorobenzene in meat and poultry in the food supply of the USA

Since the early 1970s, the Food Safety and Inspection Service of the US Department of Agriculture has monitored fat samples from meat and poultry for residues of hexachlorobenzene (HCB). The violative level for enforcement activities is 0.5 ppm. Data on HCB residues found in meat and poultry have been organized on the basis of nationwide occurrence over time, according to geographic groupings and according to species. A further distinction has been made between grazing animals, e.g., cattle, sheep, horses, and non-grazers such as swine and poultry. From 1972 to 1977, HCB residues were detected in all species tested. Of the samples analysed, the percentage containing HCB ranged from 7 (in 1973) to 41 (in 1977). In 1978, the percentage declined to 26 and continued to drop in 1979 to 8. From 1980 to the present time, detectable levels (greater than 0.01 ppm) of HCB have been found in 3-6% of the samples analysed with 95% of those samples containing less than 0.1 ppm. Only seven out of more than 25,000 samples analysed since 1980 contained HCB levels greater than 0.05 ppm. Comparisons of HCB in animal tissues collected from the five geographic regions of the Food Safety and Inspection Service indicated frequently that in the western and south-western regions of the USA a greater number of animals showed detectable levels of HCB in their fat. In 1984, the incidence for all samples was 4.4%. Figures for the regions varied from 1.4% in the southeast to 6.6% in the southwest. Comparison of the frequency of HCB in the fat of different species indicated that horses, sheep and cattle show detectable amounts of HCB more frequently than poultry and swine. These data seem to reflect production practices in that animals which graze at some period of their lives may be exposed to HCB more frequently than non-grazing animals.     

Hexachlorobenzene-induced renal maldevelopment in CD-1 mice and CD rats

Enlarged kidneys and hydronephrosis were observed in day-15 post-partum (pp) CD-1 mouse pups from dams treated with 10 or 50 mg hexachlorobenzene (HCB) per kg body weight (bw) on days 6-16 of gestation. Additional studies showed that enlarged kidneys occurred also on days 1 and 20 pp. CD rat pups from dams exposed to 10 mg HCB per kg bw on days 15-20 of gestation had enlarged kidneys on day 5 pp but not on days 10 or 20. In the CD rat, there was a significant increase in the kidney:bw ratio and the liver:bw ratio for the HCB-exposed pups at all three time periods. Pre- and postnatal exposure to HCB resulted in renal maldevelopment in CD-1 mice and CD rats in terms of enlarged kidneys and hydronephrosis.     

A risk analysis of hexachlorobenzene-related reproductive outcomes

Hexachlorobenzene (HCB) has been shown to produce reproductive effects in man and animals. The risks associated with hexachlorobenzene exposure have been determined for a litter using data from a feeding study by Kitchin et al. (1982). The total amount and the concentration of HCB in the litter has been estimated from a pharmacokinetic model. This estimate is consistent with the works of Kitchin et al. (1982), Courtney and Andrews (1985), and others which demonstrate that a large amount of HCB is transferred to the litter, and this quantity increases as a function of the number of lactating days. The transfer of large quantities of HCB caused a significant increase in the number of litters with greater than or equal to 10% mortality when total HCB in the litter was 29-57 mg, equivalent to a concentration of 220-310 micrograms/g. The pharmacokinetic model proved useful in estimating the total effective dose and concentration of HCB in the litter via the dam's experimental dose. The model was also able to calculate the equivalent human exposure, in order to compare it with actual HCB levels from human monitoring data.     

Phase I and pharmacologic study of a 3-hour infusion of paclitaxel followed by cisplatinum and 5-fluorouracil in patients with advanced solid tumors.

A Phase I and pharmacological study of paclitaxel administered as an outpatient, 3-h i.v. infusion just before a 5-day regimen of daily cisplatinum (CP) and a continuous infusion of 5-fluorouracil (5-FU) was performed in patients with advanced solid tumors. A secondary objective was to determine the objective response rate to this regimen. Forty-two patients were enrolled and were evaluable for toxicities. Eighteen patients were previously untreated, whereas the rest had received prior treatment with radiation (J. H. Schiller et al., J. Clin. Oncol., 12: 241-248, 1994), chemotherapy (M. J. Kennedy et al., Clin. Cancer Res., 4: 349-356, 1998), or both modalities (J. H. Schiller et al., J. Clin. Oncol., 12: 241-248, 1994). The paclitaxel dose was escalated from 100-135-170-200-225 to 250 mg/m2, whereas i.v. 5-FU and CP doses were fixed at 1.0 g/m2/day continuous infusion and 20 mg/m2/day, respectively, daily for 5 days. Granulocyte colony-stimulating factor (G-CSF; 5 microg/kg/day) was administered s.c. from day 6, routinely after 250 mg/m2 dose of paclitaxel or after a lower dose of paclitaxel if ANC <500/microl or febrile neutropenia was observed. Patients were treated every 28 days. Plasma and urine samples were collected to determine the pharmacokinetics of paclitaxel. In previously untreated patients, the maximally tolerated dose of paclitaxel in the drug regimen was determined to be 170 mg/m2 without and 250 mg/m2 with G-CSF support. At the higher dose level, mucositis and thrombocytopenia were dose-limiting. In previously treated patients, these toxicities were observed at all dose levels of paclitaxel > or =135 mg/m2. With increasing doses of paclitaxel, a disproportionate increase in the peak concentrations, as well as the area under plasma concentration time-curve, was seen. This nonlinearity was due to saturable total body clearance and volume of distribution of paclitaxel (P < 0.001). The apparent plasma elimination half-life was unaffected by the dose of paclitaxel. CP and 5-FU had no apparent effect on the metabolism of paclitaxel. Among 32 patients evaluable for response, 22 demonstrated an objective response, including five complete remissions. Therefore, a regimen of 3-h infusion of 250 mg/m2 paclitaxel before CP and FU is tolerable with G-CSF (as above) support in previously untreated patients. The regimen also seems to be highly active against breast and esophageal cancers.     

Cancer risk assessment for crotonaldehyde and 2-hexenal: an approach

Crotonaldehyde and 2-hexenal are bifunctional compounds that form 1,N2-propanodeoxyguanosine adducts and are mutagenic and genotoxic; crotonaldehyde is carcinogenic. Analysis of the mutations resulting from crotonaldehyde-induced DNA damage revealed the importance of deoxyguanosine adducts. Humans are exposed ubiquitously to these compounds by various routes. The highest daily intake of crotonaldehyde is assumed to be derived from cigarette smoke (31-169 micrograms/kg body weight), and the highest intake of 2-hexenal is probably from fruit and vegetables (31-165 micrograms/kg body weight per day). Because these compounds are suspected to play on important role in carcinogenicity, we developed sensitive 32P-postlabelling techniques for DNA adducts of crotonaldehyde and hexenal, in order to improve estimates of cancer risk. The respective standards were also synthesized and characterized spectroscopically. We report here the results of the 32P-postlabelling, e.g. the stability of the adducts in respect of nuclease P1 treatment, their labelling efficiencies, thin-layer chromatography of adduct spots and the recoveries and detection limits. In untreated male Fischer 344 rats, neither crotonaldehyde nor 2-hexenal adducts were detected, but crotonaldehyde adducts were found in the tissues of rats given single doses of 200 or 300 mg/kg body weight and in the livers of rats after repeated doses of 1 or 10 mg/kg body weight. The adduct levels were higher 20 h after gavage than after 12 h. The adducts persist to a certain extent. 2-Hexenal adducts were detected in tissues of male Fischer 344 rats after gavage with single doses of 50, 200 or 500 mg/kg body weight. The highest adduct levels were measured 48 h after gavage, but no adducts were found 8 h after gavage. Two approaches for cancer risk estimation are discussed. One is based on the correlation between the covalent binding index, calculated from adduct levels, and the median toxic dose (TD50) (Lutz, 1986) and showed a cancer risk of 1 per 10(7) lives for hexenal, assuming dietary intakes of 31-165 micrograms/kg body weight per day. The other is based on a cancer incidence of 0.07 at a dose of crotonaldehyde of 4.2 mg/kg body weight per day assessed from the study of Chung et al. (1986), which can be interpreted as a risk of 5.8-18 new cases per 10(4) smokers, assuming a consumption of 30 cigarettes per day. The latter approach may, however, lead to an overestimate of the cancer risk associated with exposure to crotonaldehyde; the estimate based on our binding studies resulted in a 20-fold lower estimate of the carcinogenic risk of crotonaldehyde.     

Chemical models for possible nitrosamine artifact formation in environmental analysis

Preliminary data concerning two different phenomena of potential importance to those studying the analysis and formation of environmental N-nitroso compounds are presented. First of all, we report that inorganic nitrite in the solid phase can serve as an effective nitrosating agent for solutions of amines in certain nonaqueous media. Secondly, we describe evidence suggesting that the appearance of nitrosamines as contaminants in deionized water (Cohen, 1977; Gough et al., 1977; Fiddler et al., 1977) might result at least partly from simple, acid-catalyzed nitrosation of the amine/ammonium functional groups on the anion exchange resins used in the demineralization process. Possible implications of both phenomena are discussed and potentially useful measures for their control are suggested.     

Preclinical evaluation of 2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]-propionic acid as a modulator of etoposide in human Waldenstrom's macroglobulinemia xenograft model.

We have previously reported that XK469 (2-[4-(7-chloro-2-quinoxalinyloxyphenoxy]-propionic acid) enhances topo IIalpha expression in WSU-WM cells in vitro [E. Mensah-Osman et al., Mol. Cancer Ther., 1: 1321-1326, 2002]. To test the hypothesis that XK469-induced expression of topo IIalpha sensitizes WSU-WM cells to the topo IIalpha inhibitor etoposide (VP-16), we investigated the antitumor effects of XK469 and VP-16 in vivo, using the WSU-WM SCID xenograft model. Individual dosages of XK469 at 20-60 mg/kg/injection i.v. for a maximum-tolerated dose of 240 mg/kg were achievable in SCID mice. Simultaneous administration of a subtherapeutic dose of XK469 (20 mg/kg) and VP-16 at its maximum-tolerated dose of 15 mg/kg proved to be highly toxic and lethal. However, daily sequential treatment of XK469 given i.v. via tail vein at 20 mg/kg for a total of 120 mg/kg, followed 7 h later by VP-16 i.p. at 15 mg/kg for a total of 90 mg/kg, had no significant toxicity in SCID mice. The sequential treatment was associated with enhanced antitumor activity. Tumor growth inhibition T/C, tumor growth delay T-C, and log(10) kill for XK469 alone were 61%, 3 days and 0.46; VP-16 alone 6%, 12 days and 1.83, respectively; whereas the sequential administration of both agents gave a T/C value of 0%, T-C value of 23 days and a log(10) kill of 3.5. On the basis of these animal results, we conclude that the sequential treatment of WSU-WM tumors with XK469 and VP-16 was highly active. The study supports our in vitro observation that XK469 potentiates VP-16 activity. The sequential use of both agents resulted in clinically significant antitumor activity in the WM model.     

Accumulation of O6-methylguanine in human blood leukocyte DNA during exposure to procarbazine and its relationships with dose and repair

O6-Methylguanine was measured by a competitive repair assay in blood leukocyte DNA of seven patients with Hodgkin's or non-Hodgkin's lymphoma during therapeutic exposure to procarbazine involving three daily p.o. doses (50 mg each) for 10 days (corresponding to 2.1 mg/kg/day for a 70-kg human). Adduct accumulation was observed in all seven cases, reaching levels up to 0.28 fmol/microgram of DNA (0.45 mumol/mol of guanine). In one individual, maximal levels of adduct were reached after 7 days of exposure, followed by a steady decline, whereas in all other individuals continuous accumulation was observed throughout the exposure period. In four individuals for which data were available for Day 11 (12 to 16 h after the final intake of procarbazine), decreased amounts of O6-methylguanine were observed relative to the last previous measurements. The accumulation of O6-methylguanine was linearly correlated (P less than 0.01) with the cumulative dose of procarbazine, with a slope of 0.011 fmol of O6-methylguanine/microgram of DNA per mg/kg of body weight or 2.68 x 10(-4) fmol of O6 methylguanine DNA per mg/m2. (Two h after the administration of single p.o. doses of 1 to 10 mg/kg of procarbazine to rats, O6-methylguanine formation in leukocyte DNA was just under half that in liver DNA and showed a linear relationship with dose with a slope of 0.017 fmol/microgram of DNA per mg/kg of body weight or 5.67 x 10(-4) fmol of O6-methylguanine/microgram of DNA per mg/m2. A negative correlation (P less than 0.05) between the rate of accumulation of O6-methylguanine in different individuals and lymphocyte O6-alkylguanine-DNA alkyltransferase (AGT) was observed, demonstrating a probable protective effect of AGT against the accumulation of O6-methylguanine during exposure to methylating agents. This observation supports the suggestion of a possible role of procarbazine-induced O6-methylguanine in the pathogenesis of acute nonlymphocytic leukemia appearing after treatment with chemotherapeutic protocols which include procarbazine, based on the finding of low lymphocyte AGT levels in patients with such therapy-related neoplastic disease (Sagher et al., Cancer Res., 48: 3084-3089, 1988). Lymphocyte AGT levels were mainly in the range of 5 to 10 fmol/micrograms of DNA and showed no consistent variation during procarbazine exposure.     

Antitumor effects of two polyamine antimetabolites combined with mitomycin C on human stomach cancer cells xenotransplanted into nude mice

The antitumor effects of alpha-difluoromethylornithine (DFMO), methylglyoxal-bis-guanylhydrazone (MGBG) and mitomycin C (MMC), administered separately or in various combinations, on human stomach cancer cells xenotransplanted into BALB/c nude mice were studied using the protocol of Battelle's Columbus Laboratories (Ovejera et al., 1978). DFMO (1,000 mg/kg in 2 divided doses) and MGBG (50 mg/kg) were given intraperitoneally (i.p.) for 7 consecutive days from the time when the tumor weighed about 100 mg. MMC (2 mg/kg) was given i.p. every other day from the same time. Animals treated with either DFMO or MGBG alone displayed tumor growth comparable to that seen in untreated controls. In mice treated with DFMO plus MGBG with or without MMC, or in mice treated only with MMC, tumor growth was significantly lower than in untreated mice. In the group which received only combined DFMO/MGBG there was a rapid regrowth of the tumor after termination of therapy. Tumor putrescine levels decreased within 4 days following the administration of DFMO; however, spermidine levels did not decline with either DFMO or MGBG treatment even after 7 days. When combined DFMO/MGBG was given, there was a significant decline in spermidine levels 7 days after the initiation of treatment. In contrast, when MMC alone was administered, putrescine and spermidine levels in the tumor did not differ from those in control mice. Spermine decreased markedly in tumor with the combined administration of DFMO/MGBG as well as with combined DFMO/MGBG/MMC, but decreased only slightly when MMC alone or MMC plus either DFMO or MGBG was administered. By the 7th treatment day, DNA biosynthesis in the tumor had dropped markedly in all groups except those receiving DFMO or MGBG alone.     

Enhancement by iron of hepatic neoplasia in rats caused by hexachlorobenzene

Female F344 rats received an i.p. injection of iron-dextran(600 mg Fe/kg) and then after 1 week were fed a diet containing0.02% hexachlorobenzene (HCB) for up to 65 weeks. All rats (8/8)which received HCB after iron overload developed multiple hepaticnodules whereas only 3/8 rats administered HCB alone had nodules(average of one per positive liver). These hyperplastic regionswere depleted of iron and were often positive for     

Serum levels of methotrexate by the ligand-binding assay after "high-dose" therapy for osteosarcoma.

The method of Arons et al. (Cancer Res. 35:2033-2038, 1975) for assaying methotrexate (MTX) was used to monitor serum levels of the drug attained in 18 patients with osteosarcomas. The patients received either 100 mg or 200 mg of MTX/kg via a 6-hour infusion. With one fatal exception, unacceptable toxicity to MTX was prevented by leucovorin. Serum levels of the drug were assayed routinely at 6, 12, and 18 hours after termination of the infusion. Although significantly higher serum levels of MTX were observed at 6 hours after the infusion of 200 mg MTX/kg than after 100 mg/kg, the variation in rate of clearance of individual patients masked any subsequent dosage-related differences. The mean half-time for clearance of MTX was similar irrespective of the dosage of MTX and was 2.91 +/- 1.51 hr for 53 treatments. The single incidence of toxicity, requiring hospitalization, was accompanied with markedly higher serum levels of MTX at 18 hours, but not at either 6 or 12 hours after termination of the drug infusion, and by a slightly slower rate of clearance, 6.2 hours. Certain minor adaptations were incorporated in the original assay to simplify the analysis of data.     

Review of comparative studies between conventional and liposomal amphotericin B (Ambisome) in neutropenic patients with fever of unknown origin and patients with systemic mycosis

Fungal infections are an important cause of morbidity and mortality in immunocompromised patients. Treatment with amphotericin B is the main therapeutic approach. However, this treatment is limited by the substantial toxicity. We present the data of the first randomized prospective comparative trial in adults (134 patients with fever of unknown origin) with conventional amphotericin B and a liposomal formulation of amphotericin B (AmBisome, published in 1997 by Prentice et al. (Br. J. Haematol. 98, 711-718) and the data of adults with documented fungal infections (59 patients), treated in this trial. Patients received either conventional amphotericin B 1 mg kg-1 per day, liposomal amphotericin B 1 mg kg-1 per day or liposomal amphotericin B 3 mg kg-1 per day. Patients were entered if they had fever of unknown origin (FUO), defined as temperature of 38 degrees C or more, not responding to 96 h of systemic broad-spectrum antibiotic treatment, and neutropenia (< 0.5 x 10(9) l-1). Efficacy of treatment was assessed, with success defined as resolution of fever for three consecutive days (< 38 degrees C) in the group of patients with FUO and the freedom of clinical signs and/or the elimination of fungus in the group of patients with documented fungal infections. The safety of treatment and renal and hepatic toxicity of liposomal and conventional amphotericin B were compared. No statistically significant difference was found in the treatment efficacy in the three study arms. However, there is a tendency of better treatment results in the two groups of patients, who received liposomal amphotericin B. Thirty-five per cent of patients with documented fungal infections and 46% of patients with FUO responded to amphotericin B. In the patients group, that received 1 mg kg-1 liposomal amphotericin B it was 63 and 49%, in the group of patients that received 3 mg kg-1 liposomal amphotericin B it was 47 and 64%. Evidence of toxicity due to amphotericin B was seen in 50 patients (83%), toxicity due to liposomal amphotericin B, 1 mg kg-1, was seen in 35 patients (50%), and due to liposomal amphotericin B 3 mg kg-1 in 34 patients (54%). This was a statistically significant difference (P = 0.001). It was concluded that liposomal amphotericin B was safer than conventional amphotericin B, but both formulations are equivalent in treatment efficacy. The prophylactic use of amphotericin B in these immunocompromised patients is discussed.     

The effect of phenobarbital on cyclophosphamide antitumor activity.

We have used the spleen colony assay system and survival duration studies in male DBA/2 mice with P388 leukemia to study the effects of microsomal enzyme induction by phenobarbital on the antileukemic activity and bone marrow toxicity of cyclophosphamide. Phenobarbital drinking water (0.5 mg/ml) was given for 7 days prior to cyclophosphamide (10 to 200 mg/kg i.p.). Average daily phenobarbital intake per mouse was 1.25 mg (equivalent to 4 mg/kg/day human dosage). Dose-response curves with and without phenobarbital pretreatment showed a constant 90% (1-log) reduction in the toxicity of cyclophosphamide to leukemic colony-forming units, whereas enzyme induction had no effect on the toxicity of the drug to normal bone marrow colony-forming units. Parallel survival studies confirmed the 1-log diminution in the antileukemic activity of cyclophosphamide in phenobarbital-pretreated mice. This phenobarbital-induced change in the antitumor activity of cyclophosphamide appears explainable on a pharmacokinetic basis. The Friedman and Boger assay for plasma alkylating metabolites showed that the reduction in the area under the plasma metabolite curve caused by enzyme induction exactly predicted the observed reduction in cyclophosphamide antitumor effect.     

Mobilization, redistribution and excretion of hexachlorobenzene following food restriction in rats

Adult female rats were given a single oral dose of hexachlorobenzene (HCB) (100 mg/kg, 1% carboxy methyl cellulose) by stomach tube. Six days after HCB dosage the diet of the animals was restricted to 30% of their normal intakes for 7 days. Following dosage and during partial starvation faecal elimination of HCB was monitored. The animals were killed on day 13 and their tissues removed for HCB analysis. A significant increase in HCB was found in all tissues, notably in the brain (367%) and the liver (496%), with HCB being mobilized from fat depots to plasma and then redistributed. The pattern of HCB faecal elimination suggests that food restriction enhances non-biliary excretion, correlating with plasma levels and faecal volume.     

Thrombospondin-1 plus irinotecan: a novel antiangiogenic-chemotherapeutic combination that inhibits the growth of advanced human colon tumor xenografts in mice

Chemotherapy for the treatment of advanced or metastatic colon cancer, utilizing agents such as 5-fluorouracil (5-FU) and irinotecan (CPT-11), produce a 5-year survival of about 10%. Thus, the identification of new, effective, therapeutic regimens to treat this disease remains critically important. To this end, selected antiangiogenic agents, compounds that inhibit neovascularization, have been shown to produce a modest tumor growth-inhibitory effect with little systemic toxicity. Thus these agents are attractive candidates for use with conventional chemotherapeutic agents to treat this disease. To evaluate this approach, experiments were undertaken to assess the cytotoxic and antineoplastic activity of CPT-11 and the antiangiogenic agent thrombospondin-1 (TSP-1) in the HT-29 model of human colon cancer. These agents were chosen since CPT-11 is a camptothecin analogue efficacious in the treatment of colon cancer and TSP-1 is a human glycoprotein that possess antiangiogenic activity. As expected, in vitro studies revealed that a 5-day exposure to TSP-1 at concentrations up to 130 g/ml was not cytotoxic alone and did not affect the cytotoxicity of CPT-11, or of its active metabolite SN38, in HT-29 cells. Similarly, in human umbilical vein endothelial cells, TSP-1 alone induced only a slight cell growth-inhibitory effect and did not significantly increase the cytotoxicity of either CPT-11 or SN38. The antineoplastic activities of TSP-1 and CPT-11 were assessed in athymic (nude) female mice bearing advanced subcutaneous xenografts of HT-29 cells. Mice received TSP-1 alone (5–40 mg/kg per day) intraperitoneally (i.p.), CPT-11 alone (100–300 mg/kg, i.p.), TSP-1 (10 mg/kg per day) plus CPT-11 (125 mg/kg), or TSP-1 (20 mg/kg per day) plus CPT-11 (150 mg/kg). TSP-1 was injected daily (Monday through Friday) for 4 weeks (20 injections in total) whereas CPT-11 was administered once weekly on days 0, 7, 14 and 21. By day 28, treatment with TSP-1 alone (5, 10 or 20 mg/kg per day) induced a dose-dependent inhibition of xenograft growth. Further, treatment with 10 or 20 mg/kg per day resulted in an average treated tumor size/control tumor size (T/C) on day 28 of 0.68 (range 0.64–0.71) or 0.58 (range 0.54–0.60), respectively. CPT-11 at all doses significantly inhibited tumor growth with an average T/C value of 0.21 (range 0.15–0.27). However, the 250 and 300 mg/kg regimens induced significant toxicity and mortality. When TSP-1 was combined with CPT-11, a significant (P0.05) inhibition of tumor growth also was observed (T/C 0.17, range 0.11–0.20). Importantly, this enhanced tumor growth inhibition was obtained without significant toxicity. The therapeutic implications of these findings are discussed.Abbreviations bFGF Basic fibroblast growth factor - CPT-11 Irinotecan - 5-FU 5-Fluorouracil - HUVEC Human umbilical vein endothelial cells - i.p. Intraperitoneally - SN38 7-Ethyl-10-hydroxy camptothecin - T/C Treated tumor size/control tumor size - TSP-1 Thrombospondin-1 - VEGF Vascular endothelial growth factor This work was supported by the TJ Martell Foundation and Rhode Island Hospital.     

Continuous-infusion daunorubicin and carboplatin for high-risk acute myeloid leukemia in the elderly.

Since continuous infusion of daunorubicin and of carboplatin have shown efficacy and reduced toxicity in early phase studies in acute myeloid leukemia (AML), 34 elderly patients with high-risk AML were treated with continuous infusion daunorubicin, 30 mg/m2 per day, from day 1 to day 4, and carboplatin, 200 mg/m2 per day from day 3 to day 7. Seven patients had therapy-related AML and/or AML following a myelodysplastic syndrome at diagnosis, 15 were in first and two in second relapse, and 10 were resistant to previous anthracycline and cytarabine therapy. Nine patients or 26%, with a 95% confidence interval (CI) ranging from 18-67%, achieved complete remission, including one patient at diagnosis (14%, CI: 0-58%), seven with relapsed AML (41%, CI: 18-67%), and one with resistant AML (10%, CI: 0-45%). Median durations of neutropenia below 0.5 x 10(9)/l and of thrombocytopenia below 20 x 10(9)/l were 24 and 20 days respectively. Severe toxicity included infections in 20 patients (59%), bleeding in two (6%), cardiac anomalies in two (6%), and vomiting in one (3%). Overall four patients (12%) died from chemotherapy related toxicity and 21 (62%) had resistant disease. Median overall survival was 4 months and median disease-free survival 8 months. We conclude that this regimen had efficacy with reduced toxicity in relapsed patients. Higher dosages for the same drugs could be tolerated by better risk patients for precise evaluation of cross reactivity with cytarabine-based regimens.     

Pharmacokinetics and toxicity of continuous infusion (6S)-folinic acid and bolus 5-fluorouracil in patients with advanced cancer.

Twenty-seven patients with advanced cancer were entered in a phase I study of bolus i.v. 5-fluorouracil at a dose of 370 mg/m2/day for 5 days combined with a continuous i.v. infusion of (6S)-folinic acid for 5.5 days, starting 24 h in advance of the first 5-fluorouracil dose. The dose of (6S)-folinic acid was escalated in cohorts of patients from 250 mg/m2/day to a maximum of 1000 mg/m2/day. The pharmacokinetics of (6S)-folinic acid were studied in the 3 patients given 250 mg/m2/day and in 6 patients given 1000 mg/m2/day. The mean steady-state plasma concentrations of (6S)-folinic acid and its principal metabolite (6S)-5-methyltetrahydrofolate at the 250 mg/m2/day dose were 2.7 and 5.1 microM, respectively. Both concentrations were comparable to the concentrations produced when (6S)-folinic acid was administered as half of a (6R,S)-folinic acid mixture (E. M. Newman et al., Cancer Res., 49:5755-5760, 1989). At the 1000 mg/m2/day dose of (6S)-folinic acid, the concentration of (6S)-folinic acid was 15.3 microM, more than the 4-fold increase predicted by linear pharmacokinetics, while the concentration of (6S)-5-methyltetrahydrofolate was only 16.5 microM. The change in the ratio of the parent compound to its metabolite was accounted for by a decrease in the nonrenal clearance of (6S)-folinic acid, probably indicating saturation of its metabolism. The toxicities observed in this phase I trial, including stomatitis, diarrhea, neutropenia, and anemia, did not differ in nature or severity from those produced by 5-fluorouracil and (6R,S)-folinic acid when administered on the same schedule. Finally, the degree of toxicity did not appear to depend on the dose of (6S)-folinic acid over the range of doses tested.     

Pharmacological analysis of etoposide in elderly patients with lung cancer.

To analyze the pharmacological characteristics of etoposide in elderly patients, we conducted a Phase I trial of a 14-day administration of oral etoposide on 12 chemotherapy-naive patients, ages 75 years or older, with lung cancer. The pharmacological profiles of etoposide in elderly patients were compared with those of younger patients in our previous studies (H. Minami et al., J. Clin. Oncol., 11: 1602-1608, 1993; H. Minami et al., J. Clin. Oncol., 13: 191-199, 1995; Y. Ando et al., Jpn. J. Cancer Res., 87: 200-205, 1996). The sigmoid Emax model and logistic regression model were used for pharmacodynamic analysis. The maximum tolerated dose for elderly patients was 75 mg/body/day. The apparent oral clearance in elderly patients was 37+/-10 (mean +/- SD) ml/min, which was not different from that in younger patients (44+/-12 ml/min). The area under the concentration-versus-time curve of etoposide over the treatment period (total AUC) that produced a 50% decrease in absolute neutrophil counts was significantly different between elderly and younger patients, 14.3+/-2.5 and 21.6+/-2.7 mg x min/ml, respectively (P = 0.048). The incidence of grade 3 or 4 neutropenia at total AUC of 30 mg x min/ml (corresponding to a plasma concentration of 1.5 microg/ml for 14 days) was 81% in elderly patients but only 48% in younger patients. Although there was no pharmacokinetic difference between elderly and younger patients, equivalent exposure to etoposide resulted in severer myelosuppression in elderly patients. These findings suggest that prolonged etoposide administration with plasma concentration maintained at 1-2 microg/ml may cause severe myelotoxicity in elderly patients.