Mitoxantrone therapy increases the risk of developing secondary leukemia in patients with cancer and in patients with multiple sclerosis.
In a study of patients with prostate cancer, acute myeloid leukemia occurred in 1% (5/487) of mitoxantrone-treated patients versus no cases in the control group (0/496) not receiving mitoxantrone at 4.7 years followup.
In a prospective, open-label, tolerability and safety monitoring study of mitoxantrone treated MS patients followed for up to five years (median of 2.8 years), leukemia occurred in 0.6% (3/509) of patients. Publications describe leukemia risks of 0.25% to 2.8% in cohorts of patients with MS treated with mitoxantrone and followed for varying periods of time. This leukemia risk exceeds the risk of leukemia in the general population. The most commonly reported types were acute promyelocytic leukemia and acute myelocytic leukemia.
In 1774 patients with breast cancer who received mitoxantrone concomitantly with other cytotoxic agents and radiotherapy, the cumulative risk of developing treatment-related acute myeloid leukemia was estimated as 1.1% and 1.6% at 5 and 10 years, respectively. The second largest report involved 449 patients with breast cancer treated with mitoxantrone, usually in combination with radiotherapy and/or other cytotoxic agents. In this study, the cumulative probability of developing secondary leukemia was estimated to be 2.2% at 4 years.
Secondary acute myeloid leukemia has also been reported in cancer patients treated with anthracyclines. Mitoxantrone is an anthracenedione, a related drug. The occurrence of secondary leukemia is more common when anthracyclines are given in combination with DNA-damaging antineoplastic agents, when patients have been heavily pretreated with cytotoxic drugs, or when doses of anthracyclines have been escalated.
Symptoms of acute leukemia may include excessive bruising, bleeding, and recurrent infections.
Therapy with mitoxantrone should be accompanied by close and frequent monitoring of hematologic and chemical laboratory parameters, as well as frequent patient observation.
Systemic infections should be treated concomitantly with or just prior to commencing therapy with mitoxantrone.
See FDA-approved patient labeling (Medication Guide).
Inform patients of the availability of a Medication Guide and instruct them to read the Medication Guide prior to initiating treatment with mitoxantrone and prior to each infusion. Review the mitoxantrone Medication Guide with every patient prior to initiation of treatment and periodically during treatment. Instruct patients that mitoxantrone should be taken only as prescribed.
Advise patients that mitoxantrone can cause myelosuppression and inform patients of the signs and symptoms of myelosuppression. Advise patients that mitoxantrone can cause congestive heart failure that may lead to death even in people who have never had heart problems before, and inform patients of the signs and symptoms of congestive heart failure. Advise patients receiving mitoxantrone to treat multiple sclerosis that they should receive cardiac monitoring prior to each mitoxantrone dose and yearly after stopping mitoxantrone.
Mitoxantrone may impart a blue-green color to the urine for 24 hours after administration, and patients should be advised to expect this during therapy. Bluish discoloration of the sclera may also occur.
A complete blood count, including platelets, should be obtained prior to each course of mitoxantrone and in the event that signs and symptoms of infection develop. Liver function tests should also be performed prior to each course of therapy. Mitoxantrone therapy in multiple sclerosis patients with abnormal liver function tests is not recommended because mitoxantrone clearance is reduced by hepatic impairment and no laboratory measurement can predict drug clearance and dose adjustments.
In leukemia treatment, hyperuricemia may occur as a result of rapid lysis of tumor cells by mitoxantrone. Serum uric acid levels should be monitored and hypouricemic therapy instituted prior to the initiation of antileukemic therapy.
Women with multiple sclerosis who are biologically capable of becoming pregnant, even if they are using birth control, should have a pregnancy test, and the results should be known, before receiving each dose of mitoxantrone (see WARNINGS, Pregnancy).
Carcinogenesis — Intravenous treatment of rats and mice, once every 21 days for 24 months, with mitoxantrone resulted in an increased incidence of fibroma and external auditory canal tumors in rats at a dose of 0.03 mg/kg (0.02 fold the recommended human dose, on a mg/m2 basis), and hepatocellular adenoma in male mice at a dose of 0.1 mg/kg (0.03 fold the recommended human dose, on a mg/m2 basis). Intravenous treatment of rats, once every 21 days for 12 months with mitoxantrone resulted in an increased incidence of external auditory canal tumors in rats at a dose of 0.3 mg/kg (0.15 fold the recommended human dose, on a mg/m2 basis).
Mutagenesis — Mitoxantrone was clastogenic in the in vivo rat bone marrow assay. Mitoxantrone was also clastogenic in two in vitro assays, it induced DNA damage in primary rat hepatocytes and sister chromatid exchanges in Chinese hamster ovary cells. Mitoxantrone was mutagenic in bacterial and mammalian test systems (Ames/Salmonella and E. coli and L5178Y TK+/-mouse lymphoma).
Mitoxantrone and its metabolites are excreted in bile and urine, but it is not known whether the metabolic or excretory pathways are saturable, may be inhibited or induced, or if mitoxantrone and its metabolites undergo enterohepatic circulation. To date, post-marketing experience has not revealed any significant drug interactions in patients who have received mitoxantrone for treatment of cancer. Information on drug interactions in patients with multiple sclerosis is limited.
Following concurrent administration of mitoxantrone with corticosteroids, no evidence of drug interactions has been observed.
Hepatic Impairment — Patients with multiple sclerosis who have hepatic impairment should ordinarily not be treated with mitoxantrone. Mitoxantrone should be administered with caution to other patients with hepatic impairment. In patients with severe hepatic impairment, the AUC is more than three times greater than the value observed in patients with normal hepatic function.
Mitoxantrone is excreted in human milk and significant concentrations (18 ng/mL) have been reported for 28 days after the last administration. Because of the potential for serious adverse reactions in infants from mitoxantrone, breast feeding should be discontinued before starting treatment.
Safety and effectiveness in pediatric patients have not been established.
Multiple Sclerosis — Clinical studies of mitoxantrone did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently from younger patients. Other reported clinical experience has not identified differences in responses between the elderly and younger patients.
Hormone-Refractory Prostate Cancer — One hundred forty-six patients aged 65 and over and 52 younger patients (<65 years) have been treated with mitoxantrone in controlled clinical studies. These studies did not include sufficient numbers of younger patients to determine whether they respond differently from older patients. However, greater sensitivity of some older individuals cannot be ruled out.
Acute Nonlymphocytic Leukemia — Although definitive studies with mitoxantrone have not been performed in geriatric patients with ANLL, toxicity may be more frequent in the elderly. Elderly patients are more likely to have age-related comorbidities due to disease or disease therapy.
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