Pharmacotherapeutic group: Detoxifying agents for antineoplastic agents, ATC code: V03AF02
Two pharmacodynamic properties of dexrazoxane are described in the literature:
| | 1. Prevention of anthracycline cardiotoxicity, and |
| | 2. Antineoplastic action |
Mechanism of action
Dexrazoxane has two major mechanisms of action:
| | 1. Chelation of iron, especially through its ring-opened metabolite thus reducing the iron-dependent oxidative stress causing anthracycline-induced cardiotoxicity. |
| | 2. Inhibition of topoisomerase II. |
It is not known to what extent each of these mechanisms contributes to the preventive effect on tissue destruction following anthracycline extravasation.
The chelating property is probably also responsible for an increased urinary excretion of iron and zinc and a decreased serum concentration of calcium as described in a few studies.
Clinical efficacy and safety
The clinical programme for Savene (dexrazoxane) included two open, single-arm, multicentre studies.
The overall purpose of each trial was to investigate the efficacy of intravenous Savene in preventing tissue damage from accidentally extravasated anthracycline, and thus preventing the patients from undergoing the routinely used surgical excision of the affected tissue.
Due to the rarity of the condition only historical data could be used for comparison (demonstrating surgical rates of 35-50%, in one country 100% in biopsy proven cases).
In both studies the dosage regimen was the same. Treatment with Savene had to be started within 6 hours from the incident and was repeated after 24 and 48 hours. The first and second doses were 1000 mg/m2 and the third was 500 mg/m2.
A requirement for inclusion in the efficacy part of the study was that the anthracycline extravasation was proven by fluorescence microscopy of one or more biopsies.
For study purposes, patients with extravasations from a central venous access device (CVAD) were not included in the efficacy evaluation.
Patients with neutropenia and thrombocytopenia > CTC grade 1 (Common Toxicity Criteria) have not been included in the clinical studies.
In study TT01, 23 patients were entered and received treatment with Savene. Eighteen were evaluable for efficacy and safety and a further five patients were evaluable for toxicity only. None of the patients required surgical intervention.
In study TT02, 57 patients entered the study and received the first dose of Savene. 36 patients were evaluable for efficacy. Only one of the 36 patients required surgery.
In both studies all patients had received anthracycline. Overall, the most commonly received anthracycline was epirubicin (56% of the patients).
In both studies dexrazoxane treatment prevented the development of necrosis, allowed cancer treatment to continue as scheduled in the majority of patients (70.4%), and reduced the occurrence of sequelae (only few and mild long-term sequelae were observed).