A Phase II Trial of Imatinib Mesylate as Maintenance Therapy for Patients With Newly Diagnosed C-kit-positive Acute Myeloid Leukemia

INTRODUCTION

Adults with acute myeloid leukemia (AML) have a high rate of remission; however, more than 50% relapse. C-kit is expressed in approximately 60% of patients with de novo AML and represents a potential therapeutic target.

MATERIALS AND METHODS

Patients with newly diagnosed AML received 12 months of imatinib mesylate as maintenance therapy after the completion of post-remission therapy. The primary objective was to determine whether this approach improved progression-free survival (defined as no relapse and no death) compared with historical controls.

RESULTS

The median progression-free survival of patients < 60 years of age was 52.1 months (historical control, 13 months) and for patients ≥ 60 years of age was 10.7 months (historical control, 8 months). The median level of AF1q expression was high (9.59), and 84% of patients had moderate or high levels of drug-resistance factors.

CONCLUSIONS

Imatinib maintenance therapy may improve the outcome of newly diagnosed patients with AML who are < 60 years of age.

A Phase 1 study of imatinib mesylate in combination with cytarabine and daunorubicin for c-kit positive relapsed acute myeloid leukemia

The c-kit receptor is expressed in 95% of relapsed acute myeloid leukemias (AMLs) and mediates leukemic proliferation. We conducted a Phase 1 study of the c-kit inhibitor, imatinib mesylate (IM), in combination with cytarabine and daunorubicin (7+3) in c-kit+ relapsed AML. IM was dose escalated using a 3 by 3 design. Phosphorylated STAT5 was absent to minimally present in residual blasts on day 14 bone marrows. The maximum tolerated dose of IM was 300 mg. The dose-limiting toxicity was Grade 3-4 hepatic toxicity. The CR/CRp rate was 57%. Cytotoxic therapy that includes IM for relapsed AML is well-tolerated and effective.

Suppression of natural killer cells after acute intoxication with alcohols and cholinotropic preparations and their reactivation with T-activin

Acute poisoning with alcohols and cholinotropic preparations carboxyphosphamide and atropine (0.8 LD(50)) was modeled on male outbred mice weighing 18-24 g. The decrease in activity of natural killer cells was most pronounced after injection of atropine, but insignificant after treatment with ethanol. The inhibitory effect of ethylene glycol, methanol, and methanol on functional activity of natural killer cells in vitro directly depended on their concentration. The effects of alcohols in equimolar concentrations of 10, 100, and 500 mM were similar. Therefore, immunotoxicity of alcohols was associated with the action of their metabolites. The ability of products formed after biotransformation of ethylene glycol, methanol, and ethanol in equimolar concentrations to cause damage to natural killer cells decreased in the following order: glyoxylic acid>formic acid>acetaldehyde>glycolaldehyde>glycolic acid. T-Activin injected subcutaneously in doses of 2.5 and 5.0 microg/kg for 3 days normalized activity of natural killer cells suppressed after acute poisoning with alcohols and cholinotropic preparations.

The role of the central nervous system in the cardiovascular responses to yohimbine

Yohimbine injected intravenously or intracerebroventricularly in conscious dogs produced behavioural excitation accompanied by a rise in blood pressure and heart rate. The cardiovascular effects were reduced or abolished by hexamethonium, phenoxybenzamine and reserpine. In conscious cats intravenously administered yohimbine was depressor but intracerebroventricular administration in these animals caused a rise in blood pressure accompanied by behavioural depression. In anaesthetized or decerebrate cats yohimbine was always depressor. Yohimbine injected intracerebroventricularly produced a rise in blood pressure and heart rate in both conscious and anaesthetized rats. When administered intravenously to these animals there was a fall in blood pressure. It was concluded that the pressor action of yohimbine in conscious dogs was central in origin via the sympathetic nervous system. The different pattern of cardiovascular responses in the dog, cat and rat may be related to differences in the balance between medullary effects and effects on higher brain centres of the three species.

Cardiovascular responses to injections of cholinomimetic drugs into the cerebral ventricles of unanaesthetized dogs

1. The cardiovascular and behavioural effects of cholinomimetic drugs injected through a cannula chronically implanted into a lateral cerebral ventricle were examined in unanaesthetized dogs.2. Acetylcholine (ACh) (10-20 mug) produced an increase in arterial pressure and heart rate, the dogs became more alert, moved their heads, licked and swallowed and then became drowsy.3. The responses to ACh were potentiated by intraventricular physostigmine (5 mug), were abolished by intraventricular atropine (100 mug) but were unaffected by intraventricular mecamylamine (250 mug). The responses to ACh were reproducible on any one day if injections were given again after a 30 min interval but tolerance developed when ACh was injected repeatedly over periods of several days.4. Methacholine (40 mug) produced similar behavioural and cardiovascular effects to ACh but of a longer duration. The responses to methacholine were abolished by intraventricular atropine (100 mug).5. Nicotine (20-60 mug) produced a biphasic cardiovascular response of an initial brief pressor response and tachycardia followed by a secondary increase in arterial pressure and heart rate which was greater in magnitude and duration. The secondary cardiovascular effects were associated with restlessness and vomiting.6. The responses to nicotine were abolished by prior injection of mecamylamine (250 mug) but were unaffected by atropine (100 mug). The responses to nicotine were not reproducible if injections were repeated on the same day but could be again produced if a few days were allowed to elapse between injections.7. An increased heart rate occurred during the pressor response to the cholinomimetic drugs but when a comparable pressor response was produced by intravenous infusion of noradrenaline in the same unanaesthetized dogs pronounced reflex bradycardia resulted.8. The results indicate that the activation of both muscarinic and nicotinic cholinergic mechanisms leads to cardiovascular and behavioural effects in the conscious dog although the site of action and peripheral mechanisms have not been determined.