nolatrexed and Neoplasms

Thymidylate synthase (TS) is a folate-dependent enzyme that catalyzes the reductive methylation of 2'-deoxyuridine-5'-monophosphate to 2'-deoxythymidine-5'-monophosphate. This pathway provides the sole intracellular de novo source of 2'-deoxythymidine-5'-triphosphate; therefore, TS represents a critical target in cancer chemotherapy. 5-Fluorouracil (5-FU) was synthesized in 1957 and represents the first class of antineoplastic agents to be developed as inhibitors of TS. While 5-FU has been widely used to treat various human malignancies, its overall clinical efficacy is limited. Therefore, significant efforts have focused on the design of novel, more potent inhibitor compounds of TS. These agents fall into two main categories: folate analogs and nucleotide analogs. Five antifolate analogs are currently being evaluated in the clinic: raltitrexed, pemetrexed, nolatrexed, ZD9331, and GS7904L. Our laboratory has identified a novel mechanism of resistance that develops to TS inhibitor compounds, namely drug-mediated acute induction of new TS synthesis; this mechanism is directly controlled at the translational level. The ability of cancer cells to acutely induce the expression of TS may represent a novel mechanism for the development of cellular drug resistance. The future success of TS inhibitor compounds in the clinic may depend on novel strategies to selectively inhibit TS and on novel combination therapies to overcome cellular drug resistance.

Topics: Antineoplastic Agents; Enzyme Inhibitors; Humans; Indoles; Isoindoles; Neoplasms; Quinazolines; Randomized Controlled Trials as Topic; Thiophenes; Thymidylate Synthase

Zarix is developing Thymitaq (nolatrexed dihydrochloride) for the potential treatment of cancer. It is conducting a phase III trial in the US, Canada, South Africa and certain European countries [382746], [397955], [4061471, after review and comment by the FDA. One clinical trial may be sufficient for registration [405928]. In April 2000, Thymitaq was designated a Fast Track product for the treatment of unresectable hepatocellular carcinouna (HCC) by the FDA [364887], based on the survival analysis (intent-to-treat) of the Agouron phase II data and medical necessity [405928]. The company was expected to file an NDA in 2002 [367559]. However, as of April 2001, the company was expecting to file an NDA in the third quarter of 2003 [405928]. In January 1999, Zarix licensed worldwide rights to Thymitaq from Agouron [311213]. Agouron discontinued development of Thymitaq, based on an interim analysis of phase II/III trials which showed that although the compound was effective as a single agent in head and neck and liver tumors, it was not sufficiently better than existing therapeutics to justify further development [211844], [270994]. However, in its efforts to complete the monitoring of these studies, Zarix discovered that a great majority of patients obtained stabilization of disease with Thymitaq treatment [405928]. Zarix will focus development efforts on the treatment of HCC. Zarix is developing Thymitaq in an iv formulation for the treatment of HCC and, in May 2000, planned to initiate phase III trials in the fourth quarter of 2000 [364887]. Patient enrollment in a pivotal, phase III trial in patients with unresectable HCC comparing Thymitaq to doxorubicin was initiated in September 2000. Unresectable HCC is the first indication being pursued for FDA approval and the trial design was deemed acceptable in August 2000. The study is a multicenter, multinational trial that will utilize approximately 50 sites. It is anticipated that patient accrual will be completed within 24 months [378514], 1382746], [384018]. The company plans to file for regulatory approval of the product in North America, Europe and Japan, and will pursue development of the drug in a variety of oncology indications [311213]. The multicenter study is to be conducted as a global program with sites in the US, Canada, Europe and South Africa. In January 2001, the Canadian Therapeutic Products Directorate indicated that the design of the phase IX trial was acceptable. Zarix expected patient enro

Topics: Animals; Antimetabolites, Antineoplastic; Clinical Trials as Topic; Contraindications; Enzyme Inhibitors; Humans; Neoplasms; Quinazolines; Radiation-Sensitizing Agents; Structure-Activity Relationship; Thymidylate Synthase

A phase I study of nolatrexed, administered as a continuous 5 day intravenous infusion every 28 days, has been undertaken for children with advanced malignancy. 16 patients were treated at 3 dose levels; 420, 640 and 768 mg/m(2)24 h(-1). 8 patients were evaluable for toxicity. In the 6 patients treated at 768 mg/m(2)24 h(-1), dose-limiting oral mucositis and myelosuppression were observed. Plasma nolatrexed concentrations and systemic exposure, measured in 14 patients, were dose related, with mean AUC values of 36 mg(-1)ml(-1)min(-1), 50 mg ml(-1)min(-1)and 80 mg ml(-1)min(-1)at the 3 dose levels studied. Whereas no toxicity was encountered if the nolatrexed AUC was <45 mg ml(-1)min(-1), Grade 3 or 4 toxicity was observed with AUC values of >60 mg ml(-1)min(-1). Elevated plasma deoxyuridine levels, measured as a surrogate marker of thymidylate synthase inhibition, were seen at all of the dose levels studied. One patient with a spinal primitive neuroectodermal tumour had stable disease for 11 cycles of therapy, and in two patients with acute lymphoblastic leukaemia a short-lived 50% reduction in peripheral lymphoblast counts was observed. Nolatrexed can be safely administered to children with cancer, and there is evidence of therapeutic activity as well as antiproliferative toxicity. Phase II studies of nolatrexed in children at the maximum tolerated dose of 640 mg/m(2)24 h(-1)are warranted.

Topics: Acute Disease; Adolescent; Antimetabolites, Antineoplastic; Child; Child, Preschool; Enzyme Inhibitors; Female; Humans; Infant; Leukemia, Myeloid; Male; Neoplasms; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Quinazolines

Phase I studies of p.o. administered nolatrexed dihydrochloride (AG337, THYMITAQ), a nonclassical thymidylate synthase inhibitor, were performed to establish the maximum tolerated dose and a recommended dose for Phase II studies. The bioavailability and pharmacokinetic and pharmacodynamic properties of oral nolatrexed were also studied. Forty-five patients were treated with oral nolatrexed every 6 h for 5 days at doses of 288-1000 mg/m2/day. The bioavailability of the oral preparation was determined, and the effect of a standard meal on nolatrexed absorption was investigated at a dose of 800 mg/m2/day. Nolatrexed plasma concentrations were analyzed by high-performance liquid chromatography. Nolatrexed was rapidly absorbed with a median bioavailability of 89% (range 33-116%), with 88% of patients above 70%. The dose-limiting toxicities were gastrointestinal, and the recommended Phase II oral dose was 800 mg/m2/day. After a standard meal, the peak plasma nolatrexed concentration achieved was lower (median, 8.3 microg/ml versus 15.0 microg/ml; P = 0.001), and the time taken to reach the peak was longer (median, 180 min versus 45 min; P = 0.00003), but the trough concentration was higher (median, 3.6 microg/ml versus 2.1 microg/ml; P = 0.004) when compared with the fasted state. The area under the nolatrexed plasma concentration versus time curve was not affected by food. Average trough nolatrexed concentration, but not dose, was significantly related to the % decrease in both thrombocytes (r2 = 0.58; C50 = 6.0 microg/ml, where C50 is the plasma concentration associated with a 50% decrease in thrombocytes) and neutrophils (r2 = 0.63; C50 = 0.6 microg/ml). Nolatrexed can be safely administered as an oral preparation at a dose of 800 mg/m2/day for 5 days. Bioavailability was close to 100% and, because inhibition of thymidylate synthase by nolatrexed is rapidly reversible, the slower absorption after a standard meal may result in a shorter duration of noninhibitory concentrations between doses.

Topics: Administration, Oral; Adult; Aged; Antimetabolites, Antineoplastic; Biological Availability; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Food-Drug Interactions; Humans; Infusions, Intravenous; Male; Middle Aged; Neoplasms; Quinazolines

2-Amino-3,4-dihydro-6-methyl-4-oxo-5-(4-pyridylthio)-quinazoline dihydrochloride (nolatrexed dihydrochloride, Thymitaq, AG337), a specific inhibitor of thymidylate synthase, was developed using protein structure-based drug design. Intravenously administered nolatrexed is active clinically. As oral bioavailability is high (70-100%), nolatrexed was administered orally, 6 hourly for 10 days, at 3-week intervals, and dose escalated from 80 to 572 mg m(-2) day(-1) in 23 patients. Common toxicity criteria (CTC) grade 3 toxicities included nausea, vomiting, stomatitis and liver function test (LFT) abnormalities. Thrombocytopenia (grade 1 or 2) occurred at doses > or = 318 mg m(-2) day(-1) and neutropenia (grade 2) at 429 and 572 mg m(-2) day(-1). An erythematous maculopapular rash occurred at dosages > or = 318 mg m(-2) day(-1) (7 out of 19 patients). LFT abnormalities occurred in two out of six patients (grade 3 or 4 bilirubin and grade 3 alanine transaminase) at 572 mg m(-2) day(-1). Nolatrexed plasma concentrations 1 h after dosing were 6-16 microg ml(-1), and trough 3-8 microg ml(-1), at 572 mg m(-2) day(-1). Inhibition of thymidylate synthase was demonstrated by elevation of plasma deoxyuridine. Six-hourly oral nolatrexed for 10 days was associated with antiproliferative effects, but nausea and vomiting was dose limiting at 572 mg m(-2) day(-1). Nine patients were treated at 429 mg m(-2) day(-1); three out of nine experienced grade 3 nausea, but 17 out of 22 treatment courses were completed (with the co-administration of prophylactic antiemetics) and this dose level could be considered for phase II testing.

Topics: Administration, Oral; Adult; Antimetabolites, Antineoplastic; Biological Availability; Deoxyuridine; Dose-Response Relationship, Drug; Drug Administration Schedule; Exanthema; Humans; Liver Function Tests; Nausea; Neoplasms; Neutropenia; Quinazolines; Stomatitis; Thrombocytopenia; Thymidylate Synthase; Vomiting

To establish the maximum tolerated dose (MTD), dose-limiting and other major toxicities and the major pharmacokinetic parameters of a 10-day infusion of the nonclassical antifolate Thymitaq.. The drug was given by 10-day infusion via a portable pump. The starting dose was 286 mg/m2 per day with escalation to 572 and 716 mg/m2 per day. Thymitaq in plasma was assayed by a validated isocratic reverse-phase HPLC assay with detection at 273 nm.. The dose of 716 mg/m2 per day x 10 was considered too high as none of three patients completed a 10-day infusion and two of three developed grade IV myelotoxicity. At 572 mg/m2 per day three of four patients completed a 10-day infusion. Dose-limiting myelosuppression was seen in one of four but owing to a high incidence of thrombotic phenomena, no further patients were added.. Continuous 10-day infusions of Thymitaq should be limited to low doses until further studies can be done.

Topics: Adult; Aged; Antimetabolites, Antineoplastic; Area Under Curve; Carcinoma, Squamous Cell; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Humans; Infusions, Intravenous; Middle Aged; Neoplasms; Quinazolines

A phase I, multicenter trial of the thymidylate synthase (TS) inhibitor THYMITAQ (nolatrexed dihydrochloride; Agouron Pharmaceuticals, Inc, San Diego, CA) given by 5-day continuous infusion was performed to establish the maximum-tolerated dose (MTD) and to investigate pharmacokinetics, pharmacodynamics, and antitumor effects.. In vitro and in vivo preclinical studies demonstrated increased activity with prolonged nolatrexed exposure. In 32 patients, nolatrexed was given as a 5-day infusion at 96 to 1,040 mg/m2/d for 5 days. Pharmacokinetics were determined from high-performance liquid chromatography (HPLC) analyses of plasma and urine. In addition to studying toxicity, plasma deoxyuridine (UdR) elevations were measured as a marker of TS inhibition.. The MTD was 904 mg/m2/d for 5 days and the recommended phase II dose is 800 mg/m2/d for 5 days. The dose-limiting toxicity was neutropenia with clinically significant thrombocytopenia and mucositis. These antiproliferative toxicities of nolatrexed were predictable and reversible. A partial response that lasted 3 months occurred in a patient with metastatic colorectal cancer. Pharmacokinetics were nonlinear, with the median plasma clearance (CI) decreasing from 151 mL/min/m2 (range, 124 to 211) at 96 mg/m2/d for 5 days to 49 mL/min/m2 (range, 30 to 84) at 768 mg/ m2/d for 5 days. The half-life (t1/2) was 173 minutes (range, 43 to 784) and 18% (range, 9% to 35%) of the dose was excreted unchanged in the urine. Plasma UdR increased, but returned to pretreatment levels after the end of infusion. Hematologic toxicity was significantly related to nolatrexed plasma concentrations and dose.. Nolatrexed can be safely administered to patients at a dose of 800 mg/m2/d over 5 days by continuous intravenous infusion and this schedule is associated with antitumor effects. The phase II evaluation of nolatrexed is ongoing.

Topics: Adult; Aged; Animals; Antimetabolites, Antineoplastic; Evaluation Studies as Topic; Female; Folic Acid Antagonists; Humans; Male; Mice; Middle Aged; Neoplasms; Quinazolines; Thymidylate Synthase; Tumor Cells, Cultured

3,4-Dihydro-2-amino-6-methyl-4-oxo-5-(4-pyridylthio)-quinazolon e dihydrochloride (AG337) is a nonclassical inhibitor of thymidylate synthase (TS) designed to avoid potential resistance mechanisms that can limit the activity of classical antifolate antimetabolites. A clinical pharmacokinetic and pharmacodynamic study of AG337 given as a 24-h i.v. infusion was performed. Thirteen patients received 27 courses over the dose range 75-1350 mg/m2. Plasma AG337 concentrations were achieved which, in preclinical models, were associated with antitumor effects. AG337 clearance was saturable, and the pharmacokinetics of the drug at doses above 300 mg/m2 was best described by a one-compartment model with saturable elimination (median Km = 6.5 microgram/ml; range, 4.1-13 microgram/ml; median Vmax = 2.0 microgram/ml/h/m2; range, 0.96-5.6 microgram/ml/h/m2). Following the end of the infusion, AG337 was cleared rapidly (t1/2, 53-193 min), and levels were less than 0.2 microgram/ml in all patients by 48 h. Plasma protein binding was 96-98%, and the urinary excretion of AG337 as unchanged drug did not exceed 30% of the dose administered. Measurements of plasma deoxyuridine (dUrd) concentrations showed that doses of 600 mg/m2 and above of AG337 produced a consistent elevation in plasma dUrd levels (60-290%), suggesting that TS inhibition was being achieved in patients. However, in all cases dUrd concentrations had returned to pretreatment levels 24 h after the end of the infusion, suggesting that TS inhibition was not maintained. Local toxicity, probably due to the infusate pH, was the only significant adverse effect observed. These studies have shown that cytotoxic AG337 plasma concentrations can be readily achieved without acute toxicity and that these concentrations are associated with elevations in plasma dUrd levels. The lack of prolonged dUrd elevations indicates that extended administration should be explored using central line or p.o. administration to avoid local toxicity.

Topics: Antimetabolites, Antineoplastic; Drug Administration Schedule; Drug Eruptions; Enzyme Inhibitors; Female; Folic Acid Antagonists; Humans; Infusions, Intravenous; Male; Neoplasms; Quinazolines; Thymidylate Synthase