Vinca alkaloid skin toxicity: antidote and drug disposition studies in the mouse.

A murine (BALB/c) skin toxicity model was used to evaluate various possible antagonists to vinca alkaloid-induced skin ulceration. Reproducible dose-response relationships were developed for vinblastine (VBL) and vindesine (VDS). With vincristine (VCR) only about 70% of mice developed dose-dependent ulceration. On an equal weight basis, VCR proved to be significantly more toxic than either VBL or VDS (P less than .05 by Student's t-test). Effective local intradermal antidotes to VBL, VDS, and VCR included hyaluronidase, normal saline, and calcium leucovorin (P less than .05 by the Student's Newman-Keuls multiple range test). Mild, topical skin heating significantly reduced VCR ulceration. In contrast, diphenhydramine and sodium bicarbonate were ineffective as local antidotes. Topical skin cooling, however, significantly increased vinca-induced skin ulcers for VBL, VDS, and VCR (P less than .05). Hydrocortisone, vitamin A topical cream, and isoproterenol increased skin toxicity. [3H]VBL was given intradermally to follow the drug's pharmacokinetic disposition from the skin and adherent panniculus carnosus muscle. [3H]VBL exhibited two phases of elimination: a rapid early phase [half-life (t 1/2) of approximately equal to 30 min] and a prolonged terminal phase (t 1/2 of approximately equal to 17 hr). The application of heat increased the distributive, early phase by 0.5-2.5 hours and did not enhance the terminal elimination of the drug from skin. Intradermal hyaluronidase significantly reduced the area under the ulceration multiplied by the time curve to one-seventh the control value, the peak [3H]VBL skin concentration to one-half the control value and the terminal [3H]VBL t 1/2 in skin to one-third the control level (P less than .05 by Student's t-test). These results show hyaluronidase to be an effective antidote for vinca-induced skin ulceration. Local glucocorticosteroids and topical cooling are definitely contraindicated in the management of inadvertent vinca alkaloid extravasations.

Antiproliferative and antitumor activity of the 2-cyanoaziridine compound imexon on tumor cell lines and fresh tumor cells in vitro.

BACKGROUND: Imexon, a 2-cyanoaziridine, is therapeutic and reverses lymphadenopathy and splenomegaly in the LP-BM5 murine retrovirus-induced immunodeficiency disease (murine AIDS). It can restore chemotherapy-induced immunosuppression. Imexon reduced the incidence of lymphoma in severe combined immune deficient mice inoculated with human lymphocytes. PURPOSE: To determine its antitumor activity, we screened imexon against fresh human tumor cells and tumor cell lines. To determine the time-concentration relationships of its cytotoxicity, we studied the effects of imexon on macromolecular synthesis and on the cell cycle. METHODS: Imexon was incubated at 1-200 micrograms/mL with various tumor cell lines, mitogen-stimulated peripheral blood lymphocytes, and fresh tumor cells. Cell survival, macromolecular synthesis, and cell cycle progression were studied. RESULTS: The concentration of imexon that caused 50% inhibition of growth was under 10 micrograms/mL for lymphocytes stimulated with mitogens. It was about 3-10 micrograms/mL for B-cell lymphomas and both multi-drug-resistant and -sensitive myeloma cell lines. Imexon inhibited four of seven fresh lymphoma and 11 of 16 fresh myeloma biopsy specimens to less than 40% of the control. A 1-hour exposure of lymphoma cells to 50-100 microgram/mL followed by removal of drug by washing the cells and continuing culture resulted in greater than 95% inhibition during the next 48-72 hours. Imexon selectively inhibited protein synthesis during the first 24-48 hours of exposure of lymphoma and myeloma cells. Cells exposed to inhibitory concentrations of imexon were blocked in cell cycle progression. CONCLUSION: Imexon may be a potentially useful agent in the treatment of malignant disease, particularly lymphoid malignancies, and should be explored further.

A phase I trial of beta-all-trans-retinoic acid delivered via a collagen sponge and a cervical cap for mild or moderate intraepithelial cervical neoplasia.

A phase I trial was conducted of the vitamin A derivative beta-all-trans-retinoic acid (vitamin A acid; TRA), delivered via a collagen sponge and cervical cap for mild or moderate intraepithelial cervical neoplasia. On the basis of known skin and mucosal membrane toxicity, a concentration of 0.05% TRA in a cream-based vehicle was selected as the starting dose and was escalated later with the use of a modified Fibonacchi scale. The delivery device and the TRA were changed daily for 4 days, and side effects were assessed on days 1, 2, 3, 4, 8, and 30 by clinical and colposcopic examination. Vaginal, cervical, and systemic toxicity were evaluated in 35 patients. No dose-related systemic effects were found; mild cervical inflammation increased in many patients at higher doses. Unacceptably high vaginal toxicity was reached at a TRA concentration of 0.484%. A concentration of 0.372% TRA is recommended for use in phase II trials in mild and moderate cervical intraepithelial neoplasia.

Lack of ranitidine effects on cyclophosphamide bone marrow toxicity or metabolism: a placebo-controlled clinical trial.

We previously reported that cimetidine but not ranitidine significantly enhances cyclophosphamide-induced bone marrow toxic effects and the appearance of cyclophosphamide alkylating species in a murine leukemia mouse model, and we advised caution in the use of cimetidine with microsomally metabolized anticancer drugs. Both drugs have been used for the treatment of gastric complications of chemotherapy. Using a randomized, double-blind, crossover study design, we have now evaluated the potential interaction of ranitidine with cyclophosphamide in seven cancer patients, who received two courses of cyclophosphamide, one with ranitidine and one with placebo. Four patients received ranitidine in the first course, and three received placebo. Ranitidine or placebo was started 3 days before a single dose of cyclophosphamide and given for 17 consecutive days. Ranitidine or placebo was given orally (300 mg/d), and cyclophosphamide (600 mg/m2) was given intravenously with [3H]cyclophosphamide (1000 muCi). Cyclophosphamide treatment was repeated at 4 weeks plus or minus 4 days. Blood samples were collected at intervals from 5 minutes to 24 hours after cyclophosphamide treatment and analyzed by thin-layer chromatography and radioassay for the drug and its metabolites. On days 0, 7, 14, and 21 after cyclophosphamide administration, complete blood cell counts, white blood cell differential counts, platelet counts, and SMA-17 were determined. The differences in mean nadir white blood cell counts, granulocyte counts, hemoglobin levels, and hematocrit values during ranitidine versus placebo treatment were not statistically significant. In a statistical but not a clinical sense, mean nadir platelet counts were significantly lower with ranitidine. There was a statistically significant increase in area under the curve for drug concentration in plasma x time (AUC) with ranitidine as well as a statistically significant decrease in the total-body clearance rate of the cyclophosphamide molecule. However, the effect on AUC for the major oncolytic metabolites 4-hydroxycyclophosphamide and phosphoramide mustard was not statistically significant. The lack of toxicologic or metabolic interaction between ranitidine and cyclophosphamide suggests that ranitidine can be used safely with cyclophosphamide.

Enhancement of regression of cervical intraepithelial neoplasia II (moderate dysplasia) with topically applied all-trans-retinoic acid: a randomized trial.

BACKGROUND: Retinoids enhance differentiation of most epithelial tissues. Epidemiologic studies have shown an inverse relationship between dietary intake or serum levels of vitamin A and the development of cervical dysplasia and/or cervical cancer. Pilot and phase I investigations demonstrated the feasibility of the local delivery of all-trans-retinoic acid (RA) to the cervix using a collagen sponge insert and cervical cap. A phase II trial produced a clinical complete response rate of 50%. PURPOSE: This randomized phase III trial was designed to determine whether topically applied RA reversed moderate cervical intraepithelial neoplasia (CIN) II or severe CIN. METHODS: Analyses were based on 301 women with CIN (moderate dysplasia, 151 women; severe dysplasia, 150 women), evaluated by serial colposcopy, Papanicolaou cytology, and cervical biopsy. Cervical caps with sponges containing either 1.0 mL of 0.372% beta-trans-RA or a placebo were inserted daily for 4 days when women entered the trial, and for 2 days at months 3 and 6. Patients receiving treatment and those receiving placebo were similar with respect to age, ethnicity, birth-control methods, histologic features of the endocervical biopsy specimen and koilocytotic atypia, and percentage of involvement of the cervix at study. Treatment effects were compared using Fisher's exact test and logistic regression methods. Side effects were recorded, and differences were compared using Fisher's exact test. RESULTS: RA increased the complete histologic regression rate of CIN II from 27% in the placebo group to 43% in the retinoic acid treatment group (P = .041). No treatment difference between the two arms was evident in the severe dysplasia group. More vaginal and vulvar side effects were seen in the patients receiving RA, but these effects were mild and reversible. CONCLUSIONS: A short course of locally applied RA can reverse CIN II, but not more advanced dysplasia, with acceptable local side effects. IMPLICATIONS: A derivative of vitamin A can reverse or suppress an epithelial preneoplasia, lending further support to the notion that chemoprevention of human cancer is feasible.

Modulation of experimental doxorubicin skin toxicity by beta-adrenergic compounds.

Doxorubicin [Adriamycin (ADM), a potent intercalating antineoplastic agent, occasionally causes severe local skin toxicity if extravasated during administration. Previous experiments using intradermal (i.d.) ADM in BALB/c mice have shown limited antidotal activity for local i.d. corticosteroids in preventing ADM-induced ulceration and no effect for a number of other compounds except beta-adrenergic agonists and antagonists. Three sequences of i.d. administration of beta-adrenergics were evaluated in this study: a single dose immediately after 0.05 or 0.5 mg ADM; 8 daily doses of isoproterenol (ISO) or 0.9% NaCl solution, 0.05 ml after ADM; and 5 days of pre-ADM to ostensibly "up" or "down"-regulate beta-receptor number (with propranolol and ISO, respectively). The results demonstrate consistent antidotal activity for ISO and propranolol as single antidotal injections. Terbutaline, a beta 2-specific agonist, was not effective as an antidote. Continuous daily ISO did not improve results, whereas continuous i.d. NaCl solution significantly increased skin lesion size and duration. ISO pretreatment significantly decreased subsequent ADM-induced ulceration, while propranolol pretreatment was not different from control. The results confirm a role for beta-adrenergics in the management of experimental ADM skin ulceration and suggest that local toxicity is mediated through specific beta-receptors (possibly beta 1) in the mouse skin.

Modulation of etoposide cytotoxicity and DNA strand scission in L1210 and 8226 cells by polyamines.

The anticancer agent etoposide (VP-16) produces DNA strand scission in intact tumor cells or isolated nuclei. This activity may be mediated by topoisomerase II, an enzyme capable of producing double strand breaks in mammalian cells. Two established tumor cell lines were examined to see whether polyamines, which alter DNA conformation and topoisomerase II activities, affected the cytotoxicity, strand scission, and antitumor efficacy of VP-16. L1210 murine leukemia and 8226 human myeloma cells were treated with alpha-difluoromethylornithine (DFMO) to reduce intracellular polyamine levels via inhibition of ornithine decarboxylase. The polyamines putrescine and spermidine were markedly reduced by a 48-h incubation with 50 microM DFMO. This DFMO concentration did not inhibit colony formation in either cell line, but did reduce the growth rate of both cultures. In contrast, VP-16 produced a dose-dependent inhibition of colony formation. This was especially marked in the 8226 cell line. This correlated with DNA single strand breaks (SSBs) detected by the alkaline elution technique. When cells previously treated with DFMO were exposed to VP-16, a synergistic inhibition of colony formation (determined by isobologram analysis) was observed. However, VP-16-induced SSBs were only marginally increased by the DFMO pretreatment. When putrescine was combined concurrently with VP-16, both the in vitro cytotoxic effects and the number of DNA SSBs in L1210 cells were significantly reduced. These results demonstrate that putrescine inhibits VP-16-induced SSBs and commensurate cytotoxic effects, while DFMO, which depletes intracellular putrescine and partially reduces intracellular spermidine, acts to produce synergistic cytotoxic effects when combined with VP-16.

Interaction of cimetidine but not ranitidine with cyclophosphamide in mice.

A series of experiments in DBA/2J mice evaluated the biological and pharmacokinetic interactions of the alkylating agent cyclophosphamide (CTX) and the histamine-H2 antagonists cimetidine (CMT) and ranitidine (RNT). Doses were adjusted to approximate human dose levels: 100 mg/kg for CMT; and 25 mg/kg for RNT. CMT reduced the survival of normal (bone marrow stem cell) colony forming units in a dose dependent fashion. CMT, given 5 or 30 min before CTX (200 mg/kg), significantly increased the survival of leukemia bearing mice, as well as the elimination half-life and plasma area under the curve of total alkylating metabolites of CTX. RNT did not significantly alter CTX antileukemic activity, pharmacokinetics, or toxicity to normal bone marrow stem cells. These results suggest caution in the use of CMT in patients being treated with CTX in order to avoid the possibility of exaggerated CTX toxicities. RNT may comprise a safer histamine-H2 antagonist to use with CTX if a histamine-H2 antagonist is clinically indicated.

Association of lysosomal activity with sensitivity and resistance to tumor necrosis factor in murine L929 cells.

The cytotoxic mechanism of action of tumor necrosis factor (TNF) was examined using murine L929 fibrosarcoma cells in vitro. Two cell lines were evaluated: parental TNF sensitive (L929S) (50% cytotoxic concentration, 2-6 ng/ml); and TNF resistant (L929R) (50% cytotoxic concentration, greater than 10,000 ng/ml). The latter resistant cell line was developed by serial passage in increasing concentrations of recombinant human TNF. Sensitive cells demonstrated cytolytic and cytostatic effects at TNF concentrations between 2 and 6 ng/ml, respectively. However, TNF failed to show any selective depression of RNA, DNA, or protein synthesis or ATP content in these cells until general cell death was apparent, as defined by the cell rounding and lifting off the plastic surface. The cytokine also failed to cause DNA single-strand breaks, as detected by alkaline elution techniques. TNF was also found to be no more active in glutathione-depleted cells than in target cells containing normal glutathione levels. In contrast, various nonspecific lysosomotropic agents such as ammonium chloride and D-saccharic acid lactone led to a marked inhibition of the cytotoxic action of TNF in vitro. Furthermore, significant differences in lysosomal enzyme activity were noted between L929S and L929R cells. The changes in L929R cells involved a 50% reduction in total lysosomal protein levels and a marked depression of beta-glucuronidase activity. In contrast, L929R lysosomal hexosaminidase activity was significantly elevated over the L929S cells. From these studies it is concluded that the antitumor activity of TNF does not involve specific inhibition of macromolecular synthesis, ATP production, or the level of reduced thiols. Instead, TNF cytotoxicity appears to require functional lysosomes, which are altered when TNF resistance develops in vitro.

Direct relation of DNA lesions in multidrug-resistant human myeloma cells to intracellular doxorubicin concentration.

Using a human myeloma cell line selected for resistance to doxorubicin (8226/DOX), which expresses the multidrug resistance phenotype, we studied the effects of drug accumulation on DNA damage and cytotoxicity in multidrug-resistant cells. The resistant 8226 subline showed a decrease in [14C]doxorubicin accumulation as compared to the sensitive (8226/S) subline at all time points investigated. DNA alkaline elution techniques were used to examine the formation of single and double strand breaks and DNA-protein cross-links following exposure to doxorubicin in both sensitive and resistant sublines. When 8226/S and 8226/DOX40 cells were exposed to the same extracellular concentration of doxorubicin there was a difference in the quantity of DNA lesions occurring, with the 8226/DOX40 line exhibiting less DNA damage. However, when the extracellular concentration of drug was adjusted to yield equivalent intracellular concentrations these differences were removed and both lines exhibited the same degree of damage for all three DNA lesions. The same DNA lesions were also studied in isolated nuclei from sensitive and resistant cells. Such a model removes any confounding factors due to drug accumulation such as altered cytosolic distribution and/or metabolism of drug. We observed no difference in the formation of single or double strand breaks, or DNA-protein cross-links when the nuclei were exposed to the same concentration of doxorubicin. Results from colony-forming assays have shown that when resistant and sensitive 8226 cells were exposed to high concentrations of doxorubicin, there was a good correlation between DNA damage, drug accumulation, and cytotoxicity. This relationship did not hold for lower concentrations of doxorubicin, for which there was a lack of correlation between drug accumulation and cytotoxicity. Such findings may possibly be due to a prolonged retention of drug by the sensitive cell line as compared to the resistant cells. Further studies are under way to examine this possibility.

Interactions of mitomycin C with mammalian DNA detected by alkaline elution.

The antitumor antibiotic mitomycin C (MMC) was studied in vitro using L1210 leukemia and 8226 human myeloma cells. Cytotoxicity was evaluated by colony formation in soft agar, and DNA damage was analyzed using alkaline elution filter assays. The purposes of these studies were: (a) to characterize the time course of MMC-DNA damage; (b) to characterize the type of DNA damage [DNA-DNA interstrand cross-links (ISC), DNA-protein cross-links (DPC), single and double strand breaks (SSBs, DSBs)]; and (c) to correlate this damage with cytotoxicity in vitro. Colony-forming assays showed the D0 value for 1 h MMC to be 15.0 microM for L1210 cells and 17 microM for 8226 cells. Alkaline elution studies showed that dose-dependent ISCs and DPCs formed rapidly following MMC exposure. Removal of cross-links was delayed, with only 50% repaired 32 h after exposure. There was a good correlation between ISCs and cytotoxicity in dose-response studies in each cell line. ISCs appeared to comprise most of the MMC-DNA lesions in both cell lines. No DNA SSBs or DSBs were observed following MMC exposure. Nuclei isolated from both cell lines and exposed to MMC produced less MMC alkylation than whole cells but, again, no strand breaks were evident. These results demonstrate that MMC is principally an alkylating agent when used at pharmacological (cytotoxic) concentrations in vitro. The lack of evidence for DNA strand breaks discounts a significant role for putative quinone-generated oxygen free radicals in the production of MMC cytotoxicity.

Characterization of experimental mitoxantrone cardiotoxicity and its partial inhibition by ICRF-187 in cultured neonatal rat heart cells.

Mitoxantrone cardiotoxicity was investigated in isolated neonatal rat heart myocytes treated for 3 h in the presence or absence of the metal chelator ICRF-187. Electron microscopy studies of mitoxantrone-treated myocytes showed disorganized myofibrillar structures, swollen mitochondria, and extensive vacuolization. Cardiotoxicity, reflected as the ratio of intracellular ATP/protein and the loss of spontaneous beating, was only partially reduced by continuous ICRF-187 concentrations up to 50 micrograms/ml. ICRF-187 induced myocyte protection which was dependent on the dose and duration of exposure. ICRF-187 also reduced the cardiotoxicity of doxorubicin to a lesser extent and reduced the toxicity of a postulated cyclic mitoxantrone metabolite. However, the cardiotoxicity of ametantrone, a nonmetal-binding analogue of mitoxantrone, was unaltered with ICRF-187. The antitumor activity of mitoxantrone was unaltered by ICRF-187 in human tumor cells and in P-388-bearing mice. In addition, ICRF-187 allowed for 50% greater cumulative dosing in normal mice that, nonetheless, showed extensive histological heart damage 7 wk after dosing. These studies show that ICRF-187 provides partial protection from mitoxantrone cardiotoxicity in vitro without impairing the drug's antitumor activity in vitro or in vivo. This facilitates greater cumulative drug dosing in normal mice. The postulated mechanism of cardioprotection is metal chelation, because ICRF-187 did not alter the toxicity of a nonchelating mitoxantrone analogue.

In vitro rat myocyte cardiotoxicity model for antitumor antibiotics using adenosine triphosphate/protein ratios.

Cumulative cardiotoxicity consistently limits the use of antitumor anthracyclines such as doxorubicin (DOX). Several in vivo and in vitro model systems have been developed for screening cardiotoxic agents. Problems with these models include excessive time and nonquantitative toxicity end points. We describe an in vitro system for culturing cardiac myocytes which overcomes these problems. Optimal myocyte cultures were obtained using serial 0.2% crude trypsin digestions of hearts from 1-2-day-old rats. Three-day-old myocyte cultures were treated with DOX for 6 h at concentrations of 0.1 to 10 micrograms/ml (0.18 to 18 microM). Electron microscopy performed on control and DOX-treated cultures showed characteristic histopathological signs of anthracycline damage. These changes included mitochondrial swelling, nuclear pleomorphism, chromatin clumping, and a diffuse loss of membrane integrity. Intracellular ATP, quantitated by the luciferase bioluminescence method, was shown to provide a simple and consistent quantitative biochemical marker of myocyte viability over the range of DOX concentrations used. The results showed both time- and dose-dependent decrements in ATP/protein ratios 72 h following exposure to DOX at concentrations greater than 0.1 microgram/ml. Leakage of lactate dehydrogenase activity, trypan blue uptake, and myocyte beating rates were variable and not as sensitive as ATP levels for evaluation of myocyte viability. Other cytotoxic agents which are not known to be cardiotoxic (dactinomycin, 1-beta-D-arabinofuranosylcytosine, fluorouracil, melphalan, and vincristine), required extremely high concentrations to produce myocyte damage in vitro. Tests with anthracycline analogues also demonstrated the ability of the assay to rank-order cardiotoxic agents on a weight basis: idarubicin greater than DOX greater than daunomycin greater than aclarubicin. When the in vitro drug concentrations required to lower ATP/protein ratios to 50% of controls were related to clinically achievable concentration x time products, DOX and daunomycin proved to be the most cardiotoxic in this series. These results suggest that comparative cardiotoxic screening studies may be performed in vitro using ATP levels in beating neonatal myocytes.

Antitumor activity and murine pharmacokinetics of parenteral acronycine.

The lipophilic antitumor alkaloid acronycine (ACRO) was solubilized in the cosolvent system used for etoposide. ACRO in this etoposide diluent (VPD) was found to be cytotoxic (less than or equal to 50% colony formation in soft agar) in fresh human tumors from patients with renal cell cancer, ovarian cancer, uterine cancer, and metastatic tumors of unknown primary. In P-glycoprotein-positive, multidrug-resistant (MDR) cell lines, ACRO in VPD was active in MDR Chinese hamster ovary cells but not against MDR L1210 murine leukemia cells, 8226 human myeloma cells, or human CCRF-CEM lymphoblasts. In mice, ACRO in VPD was active in two solid tumor models and an i.p. MOPC-315 plasmacytoma model. ACRO i.p. in 10% VPD (v/v%) produced significant tumor growth delays in (a) nude mice bearing human MCF-7 breast cancer xenografts and (b) C57BL mice bearing colon 38 tumor. In MOPC-315-bearing mice, a single i.p. ACRO dose of 25 mg/kg was as effective as melphalan (15 mg/kg) at prolonging life span. Finally, ACRO pharmacokinetics was evaluated in mice given single 25-mg/kg doses i.p. or p.o. The oral bioavailability of an ACRO solution in VPD was only 50% but both i.p. and p.o. regimens achieved plasma levels greater than 1.0 micrograms/ml. The plasma half-life was just under 2 h. These results show that parenteral ACRO in VPD comprises a cytotoxic antitumor agent with improved bioavailability over p.o. administration. ACRO is active in vitro against several human solid tumors but is cross-resistant in 3 of 4 MDR tumor cell lines. The prior clinical activity of p.o. ACRO in myeloma and the new results in MOPC-315 plasmacytomas in mice suggest that ACRO in VPD could have activity against human multiple myeloma.

Verapamil reversal of doxorubicin resistance in multidrug-resistant human myeloma cells and association with drug accumulation and DNA damage.

Verapamil reversed resistance to doxorubicin in a human multiple myeloma cell line selected for multiple drug resistance. The drug-resistant cell line 8226/DOX40 is known to have reduced intracellular drug accumulation associated with the overexpression of P-glycoprotein when compared to the sensitive parent cell line 8226/S. Verapamil alone was minimally cytotoxic in both cell lines, but reversed doxorubicin resistance in a dose-related manner in 8226/DOX40. A similar dose-response relationship was observed for verapamil in increasing net intracellular doxorubicin accumulation. This increased net accumulation was secondary to block of enhanced doxorubicin efflux by verapamil from resistant cells. In contrast, verapamil did not alter initial doxorubicin accumulation over the first 60 s when incubated with resistant cells. Addition of verapamil to the 8226/DOX40 cells enhanced the formation of doxorubicin-induced DNA single strand breaks, double strand breaks, and DNA-protein cross-links. Verapamil had no effect on these lesions in the drug-sensitive cells. In addition, verapamil did not affect chemotherapeutic cytotoxicity or transport in the drug-sensitive cell line. Verapamil appears to reverse doxorubicin resistance in this human myeloma cell line by blocking enhanced drug efflux, leading to increased drug accumulation and enhanced DNA damage.

Mitomycin C skin toxicity studies in mice: reduced ulceration and altered pharmacokinetics with topical dimethyl sulfoxide.

A series of toxicologic and pharmacokinetic studies were performed in BALB/c mice administered intradermal (ID) mitomycin C (MMC) at doses of .015 to 0.25 mg. Dose-dependent skin ulcers were produced at clinically relevant MMC dose levels of .05 and .075 mg (3.6 to 10.7 mg/m2). These doses produced peak ulcers of 0.15 to 0.22 cm2, respectively, one to five days after injection. The integrated ulcer area X time values (area under the curve [AUC] ulceration) were 0.89 and 3.11 cm2 X d. A large number of local pharmacologic adjuvants were found to be ineffective at reducing MMC ulceration after proximal ID injection. These included diphenhydramine, catalase, heparin, hyaluronidase, hydrocortisone, cysteine, N-acetylcysteine, lidocaine, vitamin E, and superoxide dismutase. Also, neither topical heating nor cooling of skin reduced MMC ulcerations. In contrast, a single topical application of a 100% dimethyl sulfoxide (DMSO) solution completely prevented 0.025 mg MMC-induced skin ulceration and significantly reduced .075 mg MMC ulceration (P less than .05 by multiple range tests). Topical DMSO also altered the disposition of ID MMC in mouse skin but not in plasma. Unexpectedly, the DMSO applications slowed MMC elimination from the skin. DMSO significantly increased the AUC for MMC in skin from 0.89 to 2.25 ng/h/mL of tissue (P less than .05). DMSO did not alter the degree of protein binding in skin tissue nor the in vitro chemical stability of MMC in skin tissue homogenates. These results show that experimental MMC-induced skin ulcers in mice can be ameliorated with an immediate application of topical DMSO. This effect is not due to enhanced systemic drug uptake, but may be due to reduced reactivity of MMC with target cellular nucleophiles.

Comparison of young clinical investigators' accuracy and reproducibility when measuring pulmonary and skin surface nodules using a circumferential measurement versus a standard caliper measurement: American Association for Cancer Research/American Society of Clinical Oncology Clinical Trials Workshop.

PURPOSE: The clinical investigator must understand that errors in measuring tumors can greatly affect such clinical-trial end points as tumor response. We performed a prospective, controlled study of tumor measurements that compared circumferential measurements made with a loop planimeter with linear measurements made with a standard caliper. METHODS: Using a cross-over design, 76 clinical oncology fellows/junior oncology faculty members attending a Methods in Clinical Cancer Research Workshop sponsored by the American Association for Cancer Research and the American Society of Clinical Oncology measured five pulmonary nodule phantoms that ranged in size from 1.76 to 13.21 cm(2) and five surface nodule phantoms with sizes ranging from 2.3 to 12.9 cm(2). To perform these measurements, they used both a loop planimeter and a caliper. Forty-two and 40 participants repeated measurements 3 days later on pulmonary and surface nodules. Accuracy, reproducibility, and time efficiency were evaluated. RESULTS: The linear caliper measurements overestimated pulmonary nodule and surface nodule size by a median of 37% and 23%, respectively. Circumferential loop planimeter measurements overestimated pulmonary nodule size and surface nodule size by a median of 8% and 17%, respectively. Interobserver reproducibility for the planimeter was greater than that for the caliper, as evidenced by thinner measurement interquartile ranges. Furthermore, intraobserver reproducibility was higher for the planimeter, with its variability being only 31.4% and 25.5% as large as that of the caliper when measuring the pulmonary and surface nodules, respectively. CONCLUSION: Circumferential measurements provide better accuracy, reproducibility, and speed in measuring both pulmonary and surface nodules than do perpendicular diameters.

Safety of autotransplants with high-dose melphalan in renal failure: a pharmacokinetic and toxicity study.

Melphalan (MEL) is probably the most effective chemotherapeutic agent in multiple myeloma (MM) with a clear dose-response effect. It can be escalated without excessive toxicity to 200 mg/m2, a myeloablative dose requiring hematopoietic stem cell support. Patients with marked renal insufficiency, not an infrequent finding in MM, have either received reduced doses or have been excluded from therapy with high-dose MEL. A prospective study was performed to evaluate the relationship between MEL pharmacokinetics and renal function in 20 patients with MM. Six patients had severe renal insufficiency (creatinine clearance, <40 ml/min), including five on chronic hemodialysis. Three patients with severe renal impairment first received a low test dose of MEL (16 mg/m2) for pharmacokinetic studies. All patients received 200 mg/m2 MEL divided into two equal doses of 100 mg/m2 i.v. on 2 consecutive days, followed by the administration of peripheral blood stem cells. MEL pharmacokinetics, performed after the first dose of 100 mg/m2, was not adversely affected by impaired renal function. The median half-life (t1/2), area under the concentration curve, and clearance of MEL were 1.1 h, 5.5 mg h/liter, and 27.5 liter/h, respectively, in patients with a creatinine clearance of <40 ml/min compared to 1.9, 7.9, and 23.6 for the others. Renal insufficiency also had no apparent negative impact on the quality of peripheral blood stem cell collections and did not adversely affect posttransplant engraftment, transfusion requirements, incidence of severe mucositis, or overall survival. However, it was associated with longer durations of fever (P = 0. 0005) and hospitalization (P = 0.004). No transplant-related deaths were observed. Plasma t1/2 and area under the concentration curve differed by a factor of 10 and MEL clearance by a factor of 5 between patients with the lowest and highest values. These large variations in MEL elimination could not be explained by patient or disease characteristics. We conclude that renal failure does not require dose reduction of MEL in autologous transplant. Due to marked interindividual variation in MEL elimination, pharmacokinetically guided dosing as well as cellular pharmacology studies may be helpful in achieving a more uniform antitumor effect.

Antidotes to vesicant chemotherapy extravasations.

The foregoing sections have reviewed the experimental studies and clinical anecdotes describing potential pharmacologic antidotes to extravasations of vesicant anticancer agents. Numerous prior reviews have also suggested specific antidotes or very conservative, non-pharmacologic approaches. Many antidotal approaches to extravasation have not been experimentally validated and thus, few 'antidotes' share a rationale which is founded on positive experimental and clinical studies. However, using this criteria, a few active antidotes can be distilled from the literature. These are outlined in Table 6. These antidotes include isotonic (1/6 M) sodium thiosulfate for mechlorethamine (and optionally for cisplatin), hyaluronidase for the vinca alkaloids (and optionally for epipodophyllotoxins such as etoposide), and cooling with very topical DMSO and low dose hydrocortisone for the anthracyclines. For the alkylating agent mitomycin C, topical DMSO has been effective experimentally but has not yet received clinical validation, at least in published studies. Nonetheless, the severity of mitomycin C ulcerations and the documented safety of topical DMSO in the small series of doxorubicin extravasation patients argues for its use when mitomycin extravasates in the clinic. Furthermore, except for DMSO, all of these extravasation antidotes are listed in the official FDA-approved package inserts for each vesicant agent. Thus, the inserts for vincristine and vinblastine specify hyaluronidase, for doxorubicin, glucocorticosteroids, and for mechlorethamine, sodium thiosulfate. New studies are clearly needed to clarify the role of topical DMSO with anthracyclines and mitomycin C. In addition, efforts should be made to begin clinical development of radical dimers such as DHM3 which can directly inactivate quinone-containing vesicants like doxorubicin and mitomycin C. Although the incidence of chemotherapy extravasation may be lessened with vascular access devices, it nonetheless, continues to comprise a serious and highly litigious area of oncology practice. This commands continued extravasation intervention studies and diligent prevention when ever possible.

Anticancer drug renal toxicity and elimination: dosing guidelines for altered renal function.

The narrow therapeutic index of anticancer drugs presents a clinical dilemma when these agents are administered to patients with impaired or unstable renal function. The purpose of this review is to (i) describe the nephrotoxicity of certain anticancer drugs, (ii) evaluate the fraction of renal clearance for pertinent anticancer drugs, and (iii) make general recommendations for the dosing of these drugs in the presence of impaired renal function. Pharmacokinetic, pharmacodynamic, and clinical toxicity information was obtained from current scientific and clinical literature. Recommendations for dosage adjustment of drugs is based on their nephrotoxicity, or renal clearance equal to or exceeding 30% of the administered dose. The specific formula used to calculate dosage adjustment of renally cleared anticancer drugs is based on fundamental pharmacokinetic principles. In addition, prospectively validated formulae for the dosage adjustment of specific agents, such as carboplatin are also reviewed. Forty-eight anticancer drugs are reviewed in this report. Nephrotoxicity is associated with 12 of these agents (Table 1). Renal clearance equal to or exceeding 30% of the administered dose is a characteristic of 17 of the drugs studied (Table 2), and a general recommendation for dose adjustment of these anticancer drugs is presented in Table 3. Renal clearance that is less than 30% of the administered dose is a feature of 31 anticancer drugs (Table 4) included in this review. This report provides general guidelines to adjust doses of renally excreted or nephrotoxic anticancer drugs in patients who present with altered renal function.