Alterations in adriamycin efficacy by phenobarbital.

Adriamycin dosage should be reduced in patients with impaired liver function, since adriamycin disposition is influenced by liver metabolism and biliary excretion. It follows that drugs that increase the metabolism or excretory capacity of the liver may decrease adriamycin concentrations to suboptimal values. Adriamycin metabolism was therefore studied in mice pretreated with phenobarbital (75 mg/kg i.v.) by injection. After an i.v. dose of adriamycin (30 mg/kg i.v.), plasma fluorescence due to drug and metabolites was less and disappeared at a greater rate in phenobarbital-pretreated mice than control animals. When extracted with chloroform: isoprophyl alcohol (1:1), the livers from the phenobarbital-pretreated group yielded a greater concentration of glycones. Experiments with liver microsomes confirmed that aglycone production occurred at a more rapid initial rate in phenobarbital-induced livers. No increase in aldoketo reductase (daunorubicin reductase) activity was noted. Phenobarbital-pretreated mice, inoculated i.p. with 1 million L1210 cells and then treated with adriamycin (6 mg/kg i.v.), had significantly lower survival than did controls (p less than 0.01). These findings show that phenobarbital affects the disposition of adriamycin by microsomal enzyme induction and suggest that drugs that induce microsomal enzymes should not be used concurrently with adriamycin if optimal drug efficacy is desired.

Murine metabolism and disposition of iron:adriamycin complexes.

Previous studies have reported antitumor activity and reduced cardiotoxicity for a putative 3:1 complex of iron:Adriamycin (ADR). We have studied the tissue distribution and metabolism of a wide variety of freshly prepared and lyophilized iron:ADR preparations after administration to BALB/c mice (ADR, 16 mg/kg i.v.). Tissue concentrations of ADR given without iron were initially highest in kidney and liver, and ADR fluorescence was lost from all tissues except the spleen with a t1/2 of 15 to 18 hr. ADR remained the major fluorescent species in liver and kidney from 0.5 to 72 hr after treatment. Freshly prepared iron:ADR (1:1) behaved similarly to ADR except for a slightly longer tissue t1/2 in heart, liver, and kidney. The tissue distribution of freshly prepared 2:1 and 3:1 iron:ADR was very different from that of ADR without iron; lung containing the highest concentrations of ADR fluorescence. Administration of freshly prepared 1:1, 2:1, and 3:1 iron:ADR resulted in some increase in adriamycinol in the liver, but ADR was always the major fluorescent species present. The tissue distribution of 1:1 iron:ADR that had been aged for 48 or 96 hr was similar to that of fresh 2:1 and 3:1 iron:ADR rather than ADR or fresh 1:1 iron:ADR. When lyophilized iron:ADR preparations were reconstituted and administered, the 0.5-hr tissue distribution of 0.1:1, 0.2:1, 0.25:1, and 0.33:1 iron:ADR was the same as ADR alone, but 0.5:1, 1:1, 2:1, and 3:1 iron:ADR were all accumulated primarily in the lung. Physicochemical studies confirm the production of microaggregated iron:ADR complexes and light microscopy allows visualization and sizing of these aggregates. We feel that trapping of these iron:ADR aggregates in the pulmonary vascular bed accounts for the observed dramatic alteration in tissue distribution. Light and electron microscopic studies confirm the intravascular sequestration of iron in pulmonary capillaries.

A randomized phase I/II study of continuous versus intermittent intravenous interferon gamma in patients with metastatic melanoma.

Thirty patients with documented metastatic melanoma were randomly assigned to receive recombinant DNA-produced gamma-interferon (specific activity approximately, 20 MU/mg) intravenously (IV) over either two or 24 hours at dosages of 3, 30, 300, 1,000, or 3,000 micrograms/m2. Objective toxicity resembled that of alpha-interferon and included fever, chills, myalgias, headache, and fatigue. Neutropenia, elevations in liver enzymes, tachyarrhythmias, and CNS changes also were noted. Dose-limiting toxicity included neutropenia, liver enzyme abnormality, constitutional symptoms, and a change in mental status. The incidence of toxicity was qualitatively similar in both two- and 24-hour treatment arms, but was quantitatively more severe in the 24-hour continuous infusion arm. Maximum tolerated dose was 1,000 micrograms/m2 in both schedules. Pharmacokinetic studies showed a half-life of six to nine hours. One patient had a complete response after two cycles of therapy and an additional patient entered partial remission after three cycles. Recombinant gamma-interferon (rIRN-gamma) is tolerated at dosages of 1,000 micrograms/m2 administered daily either by two or 24 hour infusion for 14 days in patients with metastatic melanoma. The responses documented in this early trial warrant further evaluation for the treatment of metastatic melanoma.

Multi-institutional phase I/II trial of oral bexarotene in combination with cisplatin and vinorelbine in previously untreated patients with advanced non-small-cell lung cancer.

PURPOSE: Bexarotene (Targretin; Ligand Pharmaceuticals, Inc, San Diego, CA) is a retinoid-X-receptor (RXR)-selective retinoid with preclinical antitumor activity in squamous cell cancers. In this phase I/II trial, we combined bexarotene with cisplatin and vinorelbine in the treatment of patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Forty-three patients who had stage IIIB NSCLC with pleural effusion or stage IV NSCLC and had received no prior therapy received bexarotene in combination with cisplatin (100 mg/m2) and vinorelbine (alternating doses of 30 mg/m2 and 15 mg/m2). In the phase I portion, the daily dose of bexarotene was escalated in cohorts of three patients from 150 mg/m2 to 600 mg/m2, beginning 1 week before the start of the cisplatin-vinorelbine regimen. Once the maximum-tolerated dose (MTD) of bexarotene was determined, the study entered the phase II portion. Response rate was the primary end point; median survival time and 1-year survival rate were secondary end points. RESULTS: In the phase I portion, the daily MTD of bexarotene was determined to be 400 mg/m2. Eight of 43 patients exhibited major responses. Seven (25%) of the 28 patients in the phase II portion responded to treatment. The median survival time in the phase II portion was 14 months; nine (32%) of the 28 patients were still alive at a minimum follow-up of 2 years. One-year and projected 3-year survival rates were 61% and 30%, respectively. The most common grade 3 and 4 adverse events were hyperlipemia, leukopenia, nausea, vomiting, pneumonia, dyspnea, anemia, and asthenia. Grade 3 and 4 laboratory abnormalities with incidences greater than 5% were decreased hemoglobin levels and WBC, absolute neutrophil, and absolute lymphocyte counts and increased prothrombin time and creatinine and amylase levels. Of the two cases of pancreatitis, one required hospitalization and both were associated with increased triglyceride levels. There was one death secondary to renal insufficiency unrelated to bexarotene treatment. CONCLUSION: In patients with advanced NSCLC, bexarotene with cisplatin and vinorelbine yielded acceptable phase II response rates (25%) and was associated with better-than-expected survival (14-month median survival time; 61% 1-year, 32% 2-year, and 30% projected 3-year survival rates). The regimen should be studied in larger clinical trials.

Predictive testing with the subrenal capsule assay.

Measurement of drug activity as an oncolytic effect, use of the control only to monitor the quality of tissue implanted, and the rapid clearance of necrotic tissue from the subcapsular site, as significant factors incorporated into the design of the assay, have permitted use of a simple tumor size parameter for evaluating drug activity. The simplicity and economy of such a parameter, the predictability and reproducibility of the 6-day assay observed thus far, and evidence that the assay does measure a biological property of the tumor apart from host response, have warranted the continued use of the 6-day time frame and the normal immunocompetent CDF1 mouse as xenograft host. These studies have demonstrated the feasibility of using human tumor explants obtained from a variety of solid human malignancies in a straightforward, short term, in vivo predictive assay system. Preliminary correlations between in vivo (assay) tumor sensitivity and clinical response have given reasonable concurrence. This crucial point will require further study, with larger numbers of patients, under more rigid conditions. Final validation of this, and other, predictive assays will require a prospective, randomized study in large numbers of patients. Our present prospective study is being continued, therefore, with expansion to a multi-institutional design over a broader geographic area.

Hemoperfusion for methotrexate removal.

Removal of methotrexate by Amberlite XAD-4 hemoperfusion was determined in a patient with metastatic breast carcinoma. During 4 hr of hemoperfusion the plasma concentration of methotrexate fell from 5.5 x 10(-7) M TO 3.1 x 10(-7) M. After hemoperfusion methotrexate concentration increased as a consequence of multicompartmental pharmacokinetics to 5.5 x 10(-7) M and then slowly declined. Plasma methotrexate clearance decreased from 79 ml/min 30 min into hemoperfusion to 28 ml/min at the conclusion. In vitro clearance of methotrexate by 17 artificial kidneys, Amberlite XAD-4, and uncoated charcoal was determined. Uncoated charcoal had the greatest clearance of methotrexate of all the devices tested. We conclude that: (1) Amberlite XAD-4 transiently reduces plasma methotrexate concentration; (2) in vitro, charcoal hemoperfusion is more effective than XAD-4 in removing methotrexate; (3) as a consequence of the multicompartmental pharmacokinetics of methotrexate a postperfusion rebound in plasma methotrexate concentration is to be expected.

Mathematical modeling -- guide to high-dose methotrexate infusion therapy.

A mathematical model that describes methotrexate pharmacokinetics has been refined for use as a guide to dose escalation during high-dose methotrexate infusion therapy. Parameters for the model are adjusted for a patients by the SAAM computer program of Berman and Weiss, on the basis of plasma concentrations obtained during the initial course of therapy. Various dose escalations can be simulated by the computer and a print-out of predicted plasma concentrations obtains. The model has been used successfully to predict plasma concentrations after high-dose infusions in patients, including those with abnormal creatinine clearances. The program is designed to allow comparisons among infusions of any duration. This can be helpful when a change from a 24-hour infusion to a 6-hour infusion is contemplated for a patient. Deviations of observed values from those predicted are used to warn of the possibility of delayed toxicity secondary to methotrexate and alert the physician that increased amounts of rescue agent may be required.

Mathematical model for adriamycin (doxorubicin) pharmacokinetics.

Adriamycin (doxorubicin), an active antineoplastic drug, is rapidly distributed across cell membranes and is concentrated within cells. Binding to protein and to tissue readily occurs. The drug is metabolized to both fluorescent and nonfluorescent compounds, the liver being the main organ of biotransformation and elimination. A multicompartment, open model that accounts for these processes has been derived. The model assumes an initial volume of distribution of 60% of body weight and includes two peripheral adriamycin compartments and a subsystem for adriamycinol, a major metabolite. Plasma and urine concentrations of adriamycin and adriamycinol were determined for four patients treated with adriamycin (60 mg/m2), and these concentrations were used to calculate rate constants for the model. Concentrations were measured by fluorescence assay after thin-layer chromatographic separation of parent compound and metabolites. Differential equations were solved by the SAAM computer program. Evaluation of adriamcinol pharmacokinetics suggests that the previously reported high concentrations of adriamycinol immediately after IV infusion of adriamycin are an artifact of the fluorescence method and that observed plasma concentrations of adriamycinol are the sum of adriamycinol concentrations and approximately 10% of the adriamycin concentrations. Corrected peak plasma concentrations of adriamycinol occur 2--12 h after infusion of adriamycin.

Pharmacokinetics of carminomycin in dogs and humans. Preliminary report.

Carminomycin was administered to four dogs and two human patients as a single intravenous dose. Plasma samples were obtained and assayed for carminomycin and carminomycinol by high pressure liquid chromatography with fluorescence detection. The plasma disappearance of carminomycin could be described by a three-compartment open model. Distribution was rapid and the apparent volume of distribution was greater than 100 l/m2 in both species. The terminal half-life of drug was 86 h in dogs and 20 h in humans. In both dogs and humans carminomycinol concentrations rapidly surpassed carminomycin levels, and terminal half-lives were longer than for the parent compound in the two species. Since carminomycinol has antitumor activity and host toxicity, this metabolite may play an important role in the efficacy and toxicity of carminomycin therapy.

Placebo-controlled trial of bexarotene, a retinoid x receptor agonist, as maintenance therapy for patients treated with chemotherapy for advanced non-small-cell lung cancer.

This study was designed as a multicenter, randomized, double-blind, placebo-controlled trial. Patients were randomized by center to placebo (16 patients, 31%), oral bexarotene 300 mg/m2/day (21 patients, 40%), or oral bexarotene 600 mg/m2/day (15 patients, 29%) following demonstration of stable or responsive disease after first-line chemotherapy. The study was prematurely terminated because of slow accrual after 54 patients enrolled. Median time to progression (TTP) from the beginning of study drug treatment was 56 days for placebo, 82 days for moderate-dose bexarotene (300 mg/m2/day), and 128 days for high-dose bexarotene (600 mg/m2/day) (P = 0.56, log-rank test). For prior chemotherapy responders only, median TTP from the beginning of study drug treatment was 56 days for placebo, 146 days for moderate-dose bexarotene, and 177 days for high-dose bexarotene. Of note, there were more chemotherapy responders randomized to the placebo group (63%) than the bexarotene treatment arms (48% and 47%), further supporting a bexarotene-related improvement in TTP. Bexarotene-related toxicity was manageable and consisted primarily of elevated serum triglycerides and asthenia, skin toxicity (dryness, peeling, flaking), thyroid dysfunction, and headache. Because this study was closed prematurely, it does not have the statistical power to detect differences among the treatment groups. This study shows that patients can tolerate bexarotene at initial doses up to 600 mg/m2/day after platinum-based chemotherapy and that bexarotene may have the potential to delay disease progression in patients with advanced non-small-cell lung cancer with previously stable or responsive disease following platinum-based chemotherapy.

In vivo kinetics of magnetically targeted low-dose doxorubicin.

The in vivo kinetics of low-dose doxorubicin (0.05 mg/kg), entrapped in a carrier and magnetically targeted, were characterized in a rat tail model. Tissue concentrations of doxorubicin at a preselected target site and in various organs were followed over time. As late as 60 min postinjection, 3.7 microgram/g of drug was found at the target site with no detectable drug levels found in any organ. In comparison, a 100-fold higher dose (5.0 mg/kg iv) of free doxorubicin yielded drug concentrations of 1.8 microgram/g at the target site and 15.0 microgram/kg in the pooled organs. Therefore, 1% of the free intravenous dose targeted magnetically yielded approximately twice the local doxorubicin concentration at a preselected target site with no detectable systemic distribution. Magnetic targeting of particulate drug carriers to localized disease sites is suggested as an efficient method of obtaining high local drug concentrations and may reduce many unwanted side effects from unrestricted systemic circulation.

Anthracycline assay by high-pressure liquid chromatography.

A general method of analysis of anthracycline concentrations was developed. Drug is extracted from plasma with organic solvent and separated from metabolites by high-pressure liquid chromatography on an aminocyanosilica column. Detection and quantitation are by the endogenous fluorescence of compounds having an intact tetracyclic ring structure. Limits of sensitivity are 5, 1, and 5 ng/ml of plasma for doxorubicin, carubicin, and marcellomycin, respectively. The assay can be used for studying the aldo-keto reductase and reductive glycosidase reactions with anthracyclines as the substrates and for the evaluation of the clinical pharmacology or pharmacodynamics of various doxorubicin analogs.

Determination of platinum in serum and ultrafiltrate by flameless atomic absorption spectrophotometry.

A graphite furnace atomic absorption spectrophotometric assay, capable of accurately determining nanogram amounts of platinum in serum and ultrafiltrate, was developed. A sample serum or ultrafiltrate was acidified with nitric acid and heated to destroy the protein-platinum bond. A measured excess of ammonium 1-pyrrolidinedithiocarbamate was added, and the platinum complex was extracted into isopropylacetone. The extract was injected into the graphite furnace. The sample was dried, charred, and atomized using optimal conditions. The resulting absorbance was used to determine the platinum content.

A phase II study of the efficacy of recombinant interferon gamma in relapsing ovarian adenocarcinoma.

Fourteen patients with relapsing ovarian cancer were treated with a regimen of intravenous interferon gamma (IFN gamma). During an initial induction phase, patients received 2 mg/m2 IFN gamma intravenously over 2 h daily for 5 days, repeated every 2 weeks for six courses. Patients who responded were continued on a maintenance phase, receiving 3 mg/m2 intravenously over 2 h, twice weekly every 2 weeks for 2 to 6 months. All patients had received prior cisplatin containing chemotherapy regimens. Of the 14 patients entered, 7 completed the six courses of the induction treatment. Four patients were clinical responders and continued on maintenance therapy. The most commonly reported toxicities included malaise, fever, and deteriorating performance status. There appears to be some clinically apparent antitumor activity demonstrated by this dosing schedule of interferon gamma in ovarian cancers.