The Drug Rediscovery protocol facilitates the expanded use of existing anticancer drugs.

The large-scale genetic profiling of tumours can identify potentially actionable molecular variants for which approved anticancer drugs are available1-3. However, when patients with such variants are treated with drugs outside of their approved label, successes and failures of targeted therapy are not systematically collected or shared. We therefore initiated the Drug Rediscovery protocol, an adaptive, precision-oncology trial that aims to identify signals of activity in cohorts of patients, with defined tumour types and molecular variants, who are being treated with anticancer drugs outside of their approved label. To be eligible for the trial, patients have to have exhausted or declined standard therapies, and have malignancies with potentially actionable variants for which no approved anticancer drugs are available. Here we show an overall rate of clinical benefit-defined as complete or partial response, or as stable disease beyond 16 weeks-of 34% in 215 treated patients, comprising 136 patients who received targeted therapies and 79 patients who received immunotherapy. The overall median duration of clinical benefit was 9 months (95% confidence interval of 8-11 months), including 26 patients who were experiencing ongoing clinical benefit at data cut-off. The potential of the Drug Rediscovery protocol is illustrated by the identification of a successful cohort of patients with microsatellite instable tumours who received nivolumab (clinical benefit rate of 63%), and a cohort of patients with colorectal cancer with relatively low mutational load who experienced only limited clinical benefit from immunotherapy. The Drug Rediscovery protocol facilitates the defined use of approved drugs beyond their labels in rare subgroups of cancer, identifies early signals of activity in these subgroups, accelerates the clinical translation of new insights into the use of anticancer drugs outside of their approved label, and creates a publicly available repository of knowledge for future decision-making.

Challenges in initiating and conducting personalized cancer therapy trials: perspectives from WINTHER, a Worldwide Innovative Network (WIN) Consortium trial.

Advances in 'omics' technology and targeted therapeutic molecules are together driving the incorporation of molecular-based diagnostics into the care of patients with cancer. There is an urgent need to assess the efficacy of therapy determined by molecular matching of patients with particular targeted therapies. WINTHER is a clinical trial that uses cutting edge genomic and transcriptomic assays to guide treatment decisions. Through the lens of this ambitious multinational trial (five countries, six sites) coordinated by the Worldwide Innovative Networking Consortium for personalized cancer therapy, we discovered key challenges in initiation and conduct of a prospective, omically driven study. To date, the time from study concept to activation has varied between 19 months at Gustave Roussy Cancer Campus in France to 30 months at the Segal Cancer Center, McGill University (Canada). It took 3+ years to be able to activate US sites due to national regulatory hurdles. Access to medications proposed by the molecular analysis remains a major challenge, since their availability through active clinical trials is highly variable over time within sites and across the network. Rules regarding the off-label use of drugs, or drugs not yet approved at all in some countries, pose a further challenge, and many biopharmaceutical companies lack a simple internal mechanism to supply the drugs even if they wish to do so. These various obstacles should be addressed to test and then implement precision medicine in cancer.

Synthesis, retention, and biological activity of methotrexate polyglutamates in cultured human breast cancer cells.

To determine the pharmacologic importance of methotrexate (MTX) polyglutamates, we examined the formation, retention, and effect of these metabolites in cultured human breast cancer cells. Two cell lines (MCF-7 and ZR-75-B) converted the drug to gamma-polyglutamate derivatives in a dose- and time-dependent reaction. After 24-h incubations with 2 muM MTX, polyglutamates of two to five amino acids in length accounted for 55.4% (51.9 nmol/g) of intracellular drug in the MCF-7 cells and 87.6% (62.4 nmol/g) of drug in ZR-75-B cells. In contrast, MDA-231 cells showed lesser accumulation of MTX, and only 32% (4.06 nmol/g) of the intracellular drug was in the form of polyglutamates, a difference that could only partially be explained by decreased ability of these cells to take up free drug from the medium. When MCF-7 and ZR-75-B cells containing polyglutamates were transferred to drug-free medium for 24 h, 22 and 51% of the total intracellular drug were, respectively, retained in each cell line. The loss of intracellular drug was primarily accounted for by disappearance of parent compound and polyglutamates containing 1-3 additional glutamyl residues. The rates of disappearance from cells decreased with increasing glutamyl chain length. All of the 4-NH(2)-10-CH(3)-PteGlu(5) and 47 and 38% of the 4-NH(2)-10-CH(3)-PteGlu(4) remained in the MCF-7 and ZR-75-B cells, respectively, and could be identified in the cytosol after 24 h in drug-free medium. The retention of MTX polyglutamates in these two cell lines in excess of dihydrofolate reductase binding capacity led to prolonged inhibition of thymidylate synthesis and loss of cell viability after removal of extracellular MTX. After 24-h incubation with 2 muM MTX and an additional 24 h in drug-free medium, [(3)H]deoxyuridine incorporation was still inhibited to 30% of control in the MCF-7 cells and 34.7% of control in ZR-75-B cells; this persistent inhibition was associated with a 30% reduction in cell numbers in each cell line during the 24-h period in drug-free medium. In contrast, [(3)H]deoxyuridine incorporation and cell growth quickly recovered to normal in the MDA-231 cells following removal of 2 muM MTX from the medium after a 24-h incubation. Prolonged inhibition of both thymidylate synthesis and cell growth was observed in this cell line in drug-free medium only after a 24-h incubation with 10 muM MTX, a condition that leads to the synthesis of 11.3 nmol/g of MTX polyglutamates. These studies demonstrate that polyglutamate formation allows a prolonged retention of drug in a noneffluxable form and prolonged inhibition of both thymidylate synthesis and cell growth following removal of extracellular drug.

Clinical pharmacokinetics of high-dose leucovorin calcium after intravenous and oral administration.

The clinical formulation of leucovorin calcium (leucovorin, LV) is a mixture of stereoisomers [(6R,S)-5-formyltetrahydrofolate], which have been shown to differ significantly in plasma clearance and route of elimination after intravenous administration; the (6S) isomer is rapidly converted to 5-CH3 tetrahydrofolate (5-CH3 THF), and the (6R) isomer is slowly eliminated by renal excretion. The relative importance of (6S) LV and 5-CH3 THF in expanding reduced folate pools in tumor cells is unknown, but it is known that high concentrations of (6R) LV can support growth of folate-depleted cells and thus have the potential to interfere with the biological activity of the (6S) isomer. To examine the pharmacokinetics of the LV isomers and metabolites, we administered 1,000 mg of LV to five normal subjects as a 2-hour intravenous infusion and in divided oral 100-mg doses given over 24 hours. Plasma and urine samples were analyzed by reverse phase followed by chiral high-performance liquid chromatography. Following intravenous administration, peak plasma concentrations of (6R) LV, (6S) LV, and 5-CH3 THF were 148 +/- 32, 59.1 +/- 22, and 17.8 +/- 17 microM, respectively. During oral administration of LV, virtually no (6S) LV appeared in the plasma. Steady-state plasma concentrations of (6R) LV and 5-CH3 THF were approximately 1.5 +/- 0.23 and 2.8 +/- 0.41 microM, respectively. Intravenous administration of LV resulted in an area under the curve (AUC) for (6R) LV that was more than four times that of the biologically active (6S) folates, whereas oral administration produced an AUC for (6S) reduced folates [(6S) LV and 5-CH3 THF] that was approximately twice that of (6R) LV. After administration of high doses of LV intravenously, conversion of (6S) LV to 5-CH3 THF was saturable, as indicated by the prolonged (6S) LV half-life of 58 minutes and the slow (6S) LV clearance of 119.2 +/- 38 mL/min, compared with previously reported data for administration of low doses. This study illustrates that intravenous administration of LV produces equivalent AUCs of (6S) LV and 5-CH3 THF but a substantially higher AUC for (6R) LV. Oral administration over 24 hours results in an AUC of 5-CH3 THF equivalent to that obtained after intravenous dosing in the presence of only small amounts of (6R) LV. The optimal route of LV administration will ultimately be determined by ongoing studies of the cellular pharmacology of LV that will determine if high concentrations of (6R) LV interfere with the biological activity of the (6S) reduced folates.

Hydroxyurea and etoposide: in vitro synergy and phase I clinical trial.

L1210 murine leukemia cells were treated with hydroxyurea (10-200 microM) for 24 hours and/or etoposide (0.17-3.4 microM) for 2 hours. Combination treatments used a fixed molar hydroxyurea:etoposide ratio of 58.9:1, and drug-drug interactions were quantitated according to the median effect principle. Hydroxyurea and etoposide were antagonistic at low doses at which the survival fraction was greater than 0.5 and synergistic at higher doses at which the survival fraction was less than 0.25. In a phase I clinical trial, 19 patients were treated with the two drugs at one of three dose levels. The dose-limiting toxic effect was myelosuppression. Doses of 100 mg of etoposide/m2 per day by continuous infusion and 500 mg of hydroxyurea orally every 4 hours, both for 3 days, are recommended for phase II trials.

Phase I trial of granulocyte-macrophage colony-stimulating factor plus high-dose cyclophosphamide given every 2 weeks: a Cancer and Leukemia Group B study.

BACKGROUND: Chemotherapy-induced myelosuppression often limits escalation of cancer chemotherapy doses. Cyclophosphamide, an alkylating agent, is an ideal candidate for dose escalation: A log-linear relationship between cell kill and dose has been demonstrated, and the drug spares hematopoietic stem cells. In addition, studies suggest that granulocyte-macrophage colony-stimulating factor (GM-CSF) can enhance the ability to achieve optimal dose intensity as well as ameliorating chemotherapy-induced myelosuppression. PURPOSE: The purpose of this study was to determine the maximum tolerated dose and the toxic effects of cyclophosphamide administered every 2 weeks with GM-CSF support. METHODS: For this trial by the Cancer and Leukemia Group B (CALGB), cohorts of patients were treated with cyclophosphamide as a 1-hour intravenous infusion every 14 days; GM-CSF was given subcutaneously on days 3-10. Four dose levels of cyclophosphamide (1.5, 3.0, 4.5, and 6.0 g/m2) and three dose levels of GM-CSF (2.5, 5.0, and 10.0 micrograms/kg per day) were evaluated. There was no dose escalation in individual patients. Fifty-one patients with solid tumors who had CALGB performance status 0 or 1 and minimal prior radiotherapy were eligible for analysis. Drug clearance and area under the curve for plasma drug concentration x time (AUC) were estimated at completion of the infusion and at 4 and 24 hours after the start of the infusion. RESULTS: Ninety-five courses of therapy were analyzed. Treatment with cyclophosphamide at 3.0 g/m2 or more resulted in neutropenia (absolute neutrophil counts < 100/microL) in all cycles of therapy. At those doses, blood cell count recovery adequate for re-treatment occurred in 67%-85% of cycles (median, 16 days). Doses of 6.0 g/m2 were associated with the greatest degree of myelosuppression and frequent hospitalization (88% of cycles); requirements for blood transfusion prohibited further dose escalation. Nonhematologic toxic effects were tolerable, with two episodes of reversible cardiotoxicity and four episodes of hemorrhagic cystitis that precluded further therapy. Degree of myelosuppression was not correlated with cyclophosphamide AUC or clearance. CONCLUSIONS: The recommended phase II dose of cyclophosphamide is 4.5 g/m2 administered every 2 weeks with GM-CSF given at 5.0 micrograms/kg per day of GM-CSF. Our results suggest that, with GM-CSF support, high cumulative doses of cyclophosphamide can be given to achieve optimal dose intensity, with reproducible blood cell count recovery and without the need for autologous bone marrow transplantation. IMPLICATIONS: Phase II studies of this intensive regimen in malignant diseases sensitive to alkylating agents are currently being done in CALGB.

Phase I study of adozelesin administered by 24-hour continuous intravenous infusion.

BACKGROUND: Adozelesin, a synthetic analogue of the antitumor antibiotic CC-1065, is the first of a class of potent sequence-specific alkylating agents to be brought to clinical trial. In preclinical in vitro testing, it has demonstrated antitumor activity at picomolar concentrations. PURPOSE: We conducted a phase I study of adozelesin to (a) determine a recommended dose for phase II testing using a 24-hour intravenous infusion, (b) characterize the toxic effects of the drug using this schedule, and (c) document any antitumor activity observed. METHODS: Adozelesin was given as a 24-hour continuous intravenous infusion. Treatments were initially scheduled every 3 weeks, but the prolonged myelosuppression observed necessitated a final dosing interval of every 6 weeks. The starting dose of 30 micrograms/m2 was escalated using a modified Fibonacci scheme until dose-limiting toxicity was encountered. RESULTS: Twenty-nine patients were entered in the study. Successive dose levels used were 30, 60, 100, 150, 120, and 100 micrograms/m2. Prolonged thrombocytopenia and granulocytopenia were dose limiting. No antitumor responses were observed. CONCLUSION: We recommend that the phase II dose of adozelesin given as a continuous 24-hour intravenous infusion be 100 micrograms/m2, repeated every 6 weeks. Other potentially less myelosuppressive schedules could be pursued.

Phase I clinical and pharmacological study of thymidine (NSC 21548) and cis-diamminedichloroplatinum(II) in patients with advanced cancer.

Studies in cell culture systems have demonstrated synergistic cytotoxicity of thymidine and its in vivo metabolite thymine with cisplatin. We have conducted a Phase I trial to assess the toxic effects and tolerable doses of thymidine plus cisplatin in patients with advanced cancer. Twenty such patients were treated with varying doses of thymidine infused continuously during Days 1-5 of a 28-day cycle. Cisplatin at a dose of 100 mg/m2 was administered on Day 3 of the cycle. Using this schedule, the maximally tolerated dose of thymidine was 60 g/m2/day. Hematological toxicity was dose limiting with median granulocyte and platelet nadirs of 1,500/mm3 and 55,000/mm3, respectively. Central nervous system and gastrointestinal toxicity was also prominent. Plasma and urine thymidine and thymine concentrations were determined using a high-performance liquid chromatography assay. At the maximally tolerated thymidine dose, steady state plasma thymidine concentrations approached or exceeded 1 mM in all patients, and thymine levels of 1-2 mM were achievable. These concentrations approach those demonstrated to produce synergistic cytotoxicity with cisplatin in vitro. Further pharmacokinetic analysis revealed that there is a progressive fall in thymidine plasma clearance with increasing dose and that cisplatin administration is followed by a significant fall in plasma thymidine clearance. No clear-cut relationships between platelet nadir and thymidine pharmacokinetics could be found, although nonlinear regression analysis did reveal a significant correlation between steady-state plasma thymidine concentration and platelet nadir. The recommended thymidine dose for Phase II trials of this combination is 60 g/m2/day in patients with little or no prior therapy.

Limited sampling models for amonafide (NSC 308847) pharmacokinetics.

The limited sampling model (LSM) offers a means of estimating the area under the concentration-time curve (AUC) from only two timed plasma concentrations. In this study, pharmacokinetic profiles were simulated for 23 patients treated with amonafide, using each patient's individual pharmacokinetic parameters. Data were simulated for a dose of 250 mg/m2 administered over 1 h. The initial 15 patients formed the training data set. Based on the training data set, five different LSMs were generated, with the multiple r ranging from 0.92 to 0.98. A single model was selected as optimal: AUC (micrograms min/ml) = 292.9 (min) C45 (micrograms/ml) + 3262 (min) C1440 (micrograms/ml) + 21.8 (micrograms min/ml) dose (mg/m2)/250 mg/m2 where C45 = 45-min plasma concentration and C1440 = 24-h plasma concentration. This model was revalidated on a second test data set of seven patients actually treated with a 1-h infusion. The relative root mean square predictive error was 15.8%, acceptable for most clinical uses. We conclude that the LSM is a powerful tool for estimation of the AUC in a large patient population. The LSM may facilitate population pharmacodynamic studies in conjunction with Phase II trials.

Synergistic cytotoxicity and DNA strand break formation by bromodeoxyuridine and bleomycin in human tumor cells.

5-Bromo-2'-deoxyuridine (BrdUrd) is a thymidine analogue whose cellular effects are related to its incorporation into DNA. BrdUrd is a known radiosensitizing agent that could potentially enhance the activity of chemotherapeutic agents that interact directly with DNA. Therefore we studied the interaction of BrdUrd and bleomycin in a human head and neck squamous carcinoma cell line, SQ20B. Using a colony-forming assay and analyzing results by the median-effect method, we have shown that there is synergistic cytotoxicity between BrdUrd and bleomycin. Synergism is evident when BrdUrd is administered prior to bleomycin or when the two drugs are applied simultaneously and is evident at a variety of BrdUrd:bleomycin concentration ratios. Alkaline elution of DNA from cells exposed to BrdUrd and bleomycin demonstrated greater single strand break formation than expected from the individual single strand break frequencies induced by each drug alone. BrdUrd did not affect the rate of repair of bleomycin-induced single strand breaks or the formation of double strand breaks. Although the mechanism of this interaction at the molecular level is unclear, our studies suggest that a direct interaction of bleomycin with BrdUrd-substituted DNA may be the cause of the synergism of these two agents.

Phase I clinical and pharmacological study of 72-hour continuous infusion of etoposide in patients with advanced cancer.

Etoposide (VP-16) is a semisynthetic epipodophyllotoxin that exhibits cell cycle phase specific cytotoxicity and enhanced effectiveness with increasing duration of drug exposure. We have therefore conducted a Phase I trial to determine the side effects, tolerable doses, and pharmacokinetic parameters of VP-16 given by continuous i.v. infusion to patients with advanced cancer. Eighteen patients were treated with varying dosages of VP-16 infused continuously for 72 consecutive hours every 28 days. Using this schedule, the maximally tolerated dosage of VP-16 was 150 mg/m2/day for patients with good performance status and 125 mg/m2/day for more debilitated cancer patients. Hematological toxicity was dose limiting with median granulocyte and platelet nadirs of 700/mm3 and 116,000/mm3, respectively, at a dose of 150 mg/m2/day. Other toxicities included only mild nausea, vomiting, and alopecia. Plasma and urine VP-16 concentrations were determined using a high-performance liquid chromatography assay. At a VP-16 dosage of 150 mg/m2/day, steady-state VP-16 concentrations were in the range of 2.1 to 7.0 micrograms/ml in all patients. Further pharmacokinetic analysis revealed that the plasma clearance of VP-16 was consistently near 25 ml/min/m2 (independent of dosage) and that renal clearance accounted for only 15% of VP-16 total plasma clearance. Patient age was found to be the most important factor correlating with plasma clearance of VP-16. Linear regression analysis also revealed that both the plasma VP-16 concentration at steady state and the concentration of VP-16 in plasma at 24 h from the start of the infusion correlated with hematological toxicity; no other patient characteristics correlated with hematological toxicity. The recommended VP-16 dose for Phase II trials of 72-h continuous infusion VP-16 is 150 mg/m2/day in patients with good performance status.

Phase I clinical and pharmacological study of iododeoxyuridine and bleomycin in patients with advanced cancer.

Studies previously performed in our laboratory demonstrated synergistic cytotoxicity and DNA strand break formation in human tumor cells following exposure to a combination of bromodeoxyuridine and bleomycin. Synergy was evident when bromodeoxyuridine was administered prior to or simultaneously with bleomycin and occurred over a wide range of concentration ratios. We therefore undertook a phase I clinical trial of the combination of iododeoxyuridine (IdUrd) and bleomycin to determine the maximally tolerated dose of IdUrd that could be administered with a standard dose of bleomycin and to determine the toxicities of the combination. Eligible patients were those with advanced cancer refractory to standard therapy who had a performance status of 0-2, measurable or evaluable disease, and adequate organ function. IdUrd was administered as a 5-day continuous i.v. infusion beginning at a dose of 250 mg/m2/day with escalation in cohorts of 3-6 patients according to a modified Fibonacci scheme. Bleomycin was administered at a dose of 15 mg/m2/day as a continuous i.v. infusion during the last 3 days of the IdUrd infusion. Cycles of therapy were repeated every 28 days. Plasma levels of IdUrd and iodouracil were determined by high performance liquid chromatography. Thirty patients received a total of 79 cycles of IdUrd/bleomycin. Dose-limiting toxicity was bone marrow suppression. At the maximally tolerated IdUrd dose of 2780 mg/m2/day, the median neutrophil nadir after the first cycle of therapy was 805/microliters and the median platelet nadir was 48,000/microliters. Other toxic effects included mucositis, fatigue, nausea, diarrhea, fever, and skin toxicity. Plasma steady-state concentrations of IdUrd increased proportionally to administered IdUrd dose. IdUrd clearance varied from 0.253 liters/min/m2 to 0.503 liters/min/m2 and did not correlate with IdUrd dose. IdUrd dose and concentration correlated significantly with granulocyte and platelet nadirs, and a pharmacodynamic model for white blood cell count nadir could be defined by pretreatment white blood cell count, IdUrd dose, and gender. The recommended IdUrd dose for phase II testing of this combination is 2140 mg/m2/day. Phase II studies will be of particular interest in those diseases, such as carcinomas of the head, neck, and esophagus, where bleomycin has documented activity as a single agent.

Phase I and pharmacokinetic study of a new antineoplastic agent: pyrazine diazohydroxide (NSC 361456).

Pyrazine diazohydroxide (PZDH) is a novel antineoplastic agent that appears to form DNA adducts via the reactive pyrazine diazonium ion and produces substantial antitumor activity in preclinical models. We conducted a phase I trial to determine the maximally tolerated dose of PZDH that could be administered as a 5-min i.v. bolus for 5 consecutive days repeated every 28 days. Thirty-one patients with advanced cancer refractory to standard therapy received a total of 65 cycles of therapy at 7 sequential PZDH dose levels: 18, 36, 45, 56, 75, 100, and 133 mg/m2/day. At the maximally tolerated dose (133 mg/m2/day x 5), all 4 patients experienced grade 3-4 thrombocytopenia, and 3 of 4 had grade 3-4 neutropenia. At the recommended phase II dose (100 mg/m2/day x 5), the median WBC nadir following the first cycle was 2.5 x 10(3)/microliters (range, 0.6-7.6) occurring on day 36, and the median platelet nadir was 87 x 10(3)/microliters (range, 9-155) occurring on day 26. Nausea and vomiting occurred at all dose levels, but were well controlled with ondansetron. No evidence of hepatic, renal, pulmonary, cardiac, venous, dermatological, or neurological toxicity was observed. Pharmacokinetic evaluations were performed on 28 of the 31 patients using an analytical method including derivatization of the parent drug to 2-chloropyrazine. We report the total 2-chloropyrazine, which represents PZDH converted per method plus PZDH converted in vivo. Although the assay quantitation limit is 10 ng/ml, PZDH could only be detected at the first dose level for 30-90 min after the i.v. bolus. Compartmental modeling of the first 4 dose levels was most consistent with a 2-compartment model. Subsequent dose levels revealed a third phase to the plasma decay curve. The area under the plasma drug concentration-time curve increased proportionally with dose; there was no evidence for dose-dependent pharmacokinetics. Pharmacokinetic parameters for 12 patients analyzed by the 3-compartment model revealed an alpha-half-life (t1/2 alpha) of 2.83 +/- 1.57 (mean +/- SD), a t1/2 beta of 11.9 +/- 4.42, and a t1/2 gamma of 161 +/- 47.1 min, with a mean clearance of 1.86 +/- 0.91 liters/min. At the 100- and 133-mg/m2 dose levels, the mean areas under the plasma drug concentration-time curve were 105 and 169 micrograms min/ml, respectively. There was a moderate correlation between body surface area and clearance (r = 0.45, P = 0.015) but a better correlation between weight and clearance (r = 0.53, P = 0.004).(ABSTRACT TRUNCATED AT 400 WORDS)

Phase I study of amonafide dosing based on acetylator phenotype.

Amonafide is extensively metabolized, including N-acetylation to an active metabolite. Prior studies have demonstrated that patients who are fast acetylators of amonafide (and other drugs) have increased toxicity at standard doses of amonafide. The primary objective of this study was to define the recommended phase II dose of amonafide separately for slow and fast acetylators. Twenty-six patients with advanced cancer underwent acetylator phenotyping with caffeine and were assigned to a dose level. Slow acetylators were treated at 375 mg/m2 (daily for 5 days) and had a median WBC nadir of 1600/microliters. Fast acetylators were treated at both 200 and 250 mg/m2, resulting in median WBC nadirs of 5300 and 2000/microliter, respectively. Two patients were not typeable, and two patients appear to have been misphenotyped, one in each phenotype category. Pharmacodynamic analysis yielded a model for nadir WBC including acetylator phenotype, 24-h N-acetyl-amonafide plasma concentration, gender, and pretreatment WBC. We recommend doses of 250 and 375 mg/m2 (for 5 days) for further phase II testing of amonafide in fast and slow acetylators, respectively.

Phase I trial and pharmacokinetics of aziridinylbenzoquinone (NSC 182986) in humans.

2,5-Diaziridinyl-3,6-(carboethoxyamino)-1,4-benzoquinone (AZQ) is a rationally designed antitumor agent which possesses sufficient lipid solubility to allow central nervous system penetration as well as adequate aqueous solubility for drug formulation and administration. We have conducted a Phase I trial of AZQ in 40 previously treated patients with advanced cancer. The drug was given as a 15-min i.v. infusion on Days 1 and 8 of a 28-day cycle. Seven dose levels ranging from 1 to 25 mg/sq m were studied with 3 to 11 patients treated at each level. Sixty-nine evaluable cycles of AZQ were administered. The major toxicity was myelosuppression, with the nadir in white blood cells and/or platelet count occurring at Days 15 to 20 of the cycle and first appearing at doses greater than 10 mg/sq m. The highest tolerated dose was 20 mg/sq m, and this dose is recommended for Phase II trials. Other toxicities were mild nausea, slight alopecia, and anemia. Plasma pharmacokinetics was studied in 11 patients by a high-performance liquid chromatography assay. Plasma decay curves could be fitted to a two-compartment open model of drug disappearance with a dose-independent terminal half-life of 33.3 +/- 4.5 (S.D.) min. Cerebrospinal fluid AZQ levels were determined in three patients and revealed readily detectable levels of AZQ.

High-dose methotrexate: a critical reappraisal.

High-dose methotrexate (HDMTX) with leucovorin (LV) rescue has been used as a therapeutic strategy in oncology for more than a decade. Administration of HDMTX results in tumoricidal plasma concentrations of the drug without significant host toxicity, provided that plasma MTX levels are monitored and LV rescue is properly administered. The original premise of LV rescue was that the provision of reduced folate to normal cells would circumvent the metabolic block produced by MTX and allow resumption of DNA synthesis, although the presumed therapeutic selectivity of leucovorin has not yet been adequately explained. Despite a strong pharmacologic rationale and a vast clinical experience, HDMTX with leucovorin rescue has not been shown to be unequivocally superior to conventional doses of MTX in any clinical situation except, perhaps, for treatment of osteogenic sarcoma and childhood acute leukemia. While HDMTX is an important component of effective treatment regimens for these diseases, its precise contribution to the success of these regimens remains undefined. Although HDMTX can theoretically overcome all known mechanisms of MTX resistance, no data exist to suggest that this can be accomplished in the clinic. Thus, this well-known but poorly understood treatment regimen must remain a subject of clinical investigation rather than a part of routine clinical practice.

Sequential hydroxyurea-cytarabine chemotherapy for refractory non-Hodgkin's lymphoma.

In experimental systems, hydroxyurea (HU) and cytarabine (ara-C) produce synergistic cytotoxicity to murine and human leukemia cells due to both cytokinetic and biochemical interactions that tend to enhance the effectiveness of ara-C. Therefore, we began a phase II trial of the combination of HU and ara-C to determine the efficacy and toxicity of this combination in treatment of patients with refractory non-Hodgkin's lymphoma. Chemotherapy began with HU 500 mg administered orally every six hours for four doses. Twelve hours following the fourth HU dose, ara-C 100 mg/m2/d was administered by continuous intravenous (IV) infusion for three days. Concomitantly with the three-day ara-C infusion, patients again received HU 500 mg orally every four hours. Cycles of therapy were repeated every 28 days. Twenty-five patients ranging in age from 26 to 70 years were enrolled in the study. Of 21 patients evaluable for response, nine (43%) obtained complete (CR) or partial remissions (PR). Most responding patients had either large-cell or cutaneous T cell lymphoma, and all but two had a performance status of 0 to 1 at entry in the study. The median survival for all responding patients was 13 months compared with 2.5 months for nonresponders. Patients obtaining a CR had a median survival of 27.5 months, and two of the four CRs remain alive and in remission at 10+ and 30+ months from achievement of CR status. The primary toxic effect of this regimen was bone marrow suppression. The median WBC nadir was 2,200 cells/microL, and the median platelet nadir was 80,000/microL. Other toxicities included mild nausea and vomiting and diffuse maculopapular rash. This biochemically rational approach to enhancing ara-C activity may have significant clinical utility and should be further explored in treatment of patients with large-cell and cutaneous T cell lymphomas.

Pharmacodynamics in cancer therapy.

Our understanding of anticancer pharmacodynamics, and the relationships between pharmacologic measurements and clinical effects, has grown markedly in recent years due to advances in analytical and computational technology. Although methotrexate plasma levels have been empirically used to guide leucovorin dosing during high-dose methotrexate therapy, there has been no other standard use of therapeutic drug monitoring in oncology. More recently, investigators have attempted to titrate precisely the dose of antineoplastic agents based on previously derived models and real-time analysis of plasma drug or tissue concentrations. Studies have been completed or are in progress using hexamethylene bisacetamide, etoposide, teniposide, fluorouracil (FUra), and cytarabine (ara-C). Future studies will focus on optimal sampling strategies, analysis of intermediate biochemical end points, combination chemotherapy, modulation by colony-stimulating factors, and more sophisticated pharmacodynamic models.

Pharmacologically based dosing of etoposide: a means of safely increasing dose intensity.

We have previously demonstrated that individualized dosing of etoposide (VP16) by 72-hour infusion is feasible and that the extent of leukopenia is a function of plasma concentration, pretreatment WBC (WBCp), albumin (ALB), performance status (PS), and bone marrow function (based on transfusion requirements). In the current study, 45 patients were randomized between a fixed dose of VP16 (125 mg/m2/d) versus individualized dosing to a target WBC nadir (WBCN) of 1,700/microL. The total dose was increased by an average of 22% in the latter patients (459 +/- 130 mg/m2 v 375 mg/m2, P = .002). This was associated with a decrease in both the mean WBCN (1,510 +/- 950 v 2,500 +/- 1,420/microL, P = .013) and in the variability of the WBCN (P = .039). The VP16 clearance (mL/min) was not correlated with body surface area. Partial responses were observed in one patient each with hepatoma and non-Hodgkin's lymphoma. We conclude that pharmacologically based dosing may be a means of increasing dose intensity without increasing the incidence of life-threatening toxicity due to a decrease in variability around a target WBC.