ABSTRACT
This phase I study was conducted to reevaluate the dose-limiting toxicities, maximum tolerated (MTD) and recommended phase II doses of oral NMF administered on a three times weekly schedule for 4 out of every 6 weeks. This schedule was based on the observation that prolonged administration of NMF was associated with the most efficacious antitumor activity in preclinical studies. Phase II trials that employed a starting dose of 800 mg/m2, determined in a previous phase I trial, were suspended because of frequent and severe toxicities. In the current study, a symptom complex characterized by nausea, vomiting, and malaise was the dose-limiting toxicity of oral NMF administered on this schedule. Other toxicities included hepatic enzyme elevations, mild myelosuppression, and worsening of preexistent toxic peripheral neuropathies. Of interest, three patients who were asymptomatic prior to treatment, rapidly developed symptoms of increased intracranial pressure after starting NMF; and, computerized tomographic brain scans revealed metastatic tumors with significant peritumoral edema. NMF was well tolerated at 600 mg/m2, however, an abrupt increase in toxicity resulted when the dose was increased to 700 mg/m2. Although NMF peak plasma concentrations (Cmax) and areas under the plasma disappearance curves (AUC) differed between the 600 and 700 mg/m2 dose levels, these differences were not striking, and similar NMF plasma concentrations and exposures were well tolerated during intravenous trials. Based on this study, the recommended phase II dose for oral NMF administered three times weekly for 4 of 6 weeks was 600 mg/m2.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Antineoplastic Agents/therapeutic use , Drugs, Investigational/therapeutic use , Formamides/therapeutic use , Administration, Oral , Adult , Aged , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/adverse effects , Chemical and Drug Induced Liver Injury , Dose-Response Relationship, Drug , Drug Administration Schedule , Drug Evaluation , Drugs, Investigational/administration & dosage , Drugs, Investigational/adverse effects , Female , Formamides/administration & dosage , Formamides/adverse effects , Humans , Male , Middle AgedABSTRACT
Dichloromethotrexate (DCMTX) has been the subject of sporadic clinical development for the last 30 years. Although DCMTX was developed in hopes of discovering a more potent antifolate, the potential pharmacologic and toxicologic advantages of the analog have become of greater interest. This phase I and pharmacokinetic trial of DCMTX given on days 1, 8, and 15 every 28 days was undertaken to test these potential advantages. The maximally tolerated dose on this schedule was 980 mg/m2. Hepatic toxicity was dose limiting. Malaise, myelosuppression, and mucositis were also major toxic effects. The recommended dose for subsequent phase II studies of DCMTX administered on this schedule is 785 mg/m2 with a reduction to 625 mg/m2 for patients with a poor performance status or extensive prior therapy. Plasma disappearance curves for most patients were biphasic or triphasic, although several demonstrated more complex kinetic patterns that suggested significant enterohepatic circulation. The magnitude of the area under the plasma disappearance curve was related to the severity of DCMTX-induced hepatotoxicity. The elimination kinetics were linear, with a mean plasma clearance of 294 mL/min (range, 128-715). The pharmacokinetic behavior of DCMTX does not support its use over methotrexate in regional perfusion. DCMTX's primarily nonrenal elimination suggests that it may have an advantage over methotrexate when combined with nephrotoxic drugs such as cisplatin. However, there is little reason to commit major resources to further evaluation of DCMTX unless significant advantages in antineoplastic activity are identified.
