Lomustine

Lomustine is indicated for the treatment of patients with primary and metastatic brain tumors following appropriate surgical and/or radiotherapeutic procedures.

Lomustine is indicated as a component of combination chemotherapy for the treatment of patients with Hodgkin's lymphoma whose disease has progressed following initial chemotherapy.

PRESCRIBE ONLY ONE DOSE FOR EACH TREATMENT CYCLE. DO NOT DISPENSE ENTIRE CONTAINER. Dispense only a sufficient number of capsules for one dose.

Confirm the total dose prescribed by the physician and the appropriate combination of capsule strengths.

Dispense only the appropriate number of lomustine capsules required for the administration of a single dose.

The prescribed dose may consist of two or more different strengths and colors of capsules.

Instruct patients that lomustine is taken as a single oral dose and will not be repeated for at least 6 weeks. Taking more than the recommended dose causes toxicities, including fatal outcomes [see Warnings and Precautions (5.2) and Overdosage (10)].

Lomustine is a cytotoxic drug. Follow applicable special handling and disposal procedures.¹

To minimize the risk of dermal exposure, always wear impervious gloves when handling bottles containing lomustine capsules. Do not break lomustine capsules; avoid exposure to broken capsules. If dermal contact occurs, wash areas of skin contact immediately and thoroughly.

The recommended dose of lomustine in adult and pediatric patients is 130 mg/m² taken as a single oral dose every 6 weeks. Round doses to the nearest 10 mg. Give as a single oral dose and do not repeat for at least 6 weeks. Reduce dose to 100 mg/m² every 6 weeks in patients with compromised bone marrow function. Also reduce dose accordingly when using with other myelosuppressive drugs.

Perform weekly complete blood counts and withhold each subsequent dose for more than 6 weeks if needed until platelet counts recover to 100,000/mm³ or greater and leukocytes recover to 4000/mm³ or greater [see Warnings and Precautions (5.1)].

Modify each dose of lomustine according to the hematologic response of the preceding dose as described in Table 1:

Lomustine causes myelosuppression that can result in fatal infections and bleeding. Myelosuppression from lomustine is delayed, dose-related, and cumulative. It usually occurs 4 to 6 weeks after drug administration and persists for 1 to 2 weeks. Thrombocytopenia is generally more severe than leukopenia. Cumulative myelosuppression from lomustine is manifested by greater severity and longer duration of cytopenias.

Monitor blood counts for at least 6 weeks after each dose. Do not give lomustine more frequently than every 6 weeks. Adjust dose based on nadir blood counts from prior dose [see Dosage and Administration (2.3)].

Fatal toxicity occurs with overdosage of lomustine. Dispensing or administering more than one dose can lead to fatal toxicity.

Prescribe only one dose at a time. Dispense only enough capsules for one dose. Both physician and pharmacist should emphasize to the patient that only one dose of lomustine is taken every 6 weeks [see Dosage and Administration (2.1) and Overdosage (10)].

Pulmonary toxicity characterized by pulmonary infiltrates and/or fibrosis occurs with lomustine. Patients with a baseline below 70% of the predicted Forced Vital Capacity (FVC) or Carbon Monoxide Diffusing Capacity (DL_CO) are at increased risk. The onset of pulmonary toxicity occurs after an interval of 6 months or longer from the start of therapy, with cumulative doses of lomustine usually greater than 1100 mg/m².

Obtain baseline pulmonary function tests prior to initiating treatment and repeat frequently during treatment. Permanently discontinue lomustine in patients diagnosed with pulmonary fibrosis.

Secondary malignancies, including acute leukemia and myelodysplasia, occur with long term use.

Hepatic toxicity, manifested by increased levels of transaminases, alkaline phosphatase, and bilirubin occurs with lomustine.

Monitor liver function.

Progressive renal failure with a decrease in kidney size occurs with lomustine.

Monitor renal function.

Based on animal data and its mechanism of action, lomustine can cause fetal harm when administered to a pregnant woman. Embryo-fetal toxicity and teratogenicity occurred in rats and rabbits receiving lomustine daily during organogenesis at doses approximately two to four times the total human dose of 130 mg/m² over 6 weeks (0.18 to 0.27 times the single human dose of 130 mg/m²) based on body surface area (BSA). Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with lomustine and for 2 weeks after the final dose. Advise males with female partners of reproductive potential to use effective contraception during treatment with lomustine and for 3.5 months after the final dose [see Use in Specific Populations (8.1, 8.3)].

Risk Summary
Based on animal data and its mechanism of action, lomustine can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1)].  There are no available data on lomustine exposure in pregnant women. Lomustine was teratogenic in rats and embryotoxic in rabbits at total dose levels approximately two to four times the total human dose of 130 mg/m² over 6 weeks (0.18 to 0.27 times the single human dose of 130 mg/m²) based on BSA [see Data].  Advise pregnant women of the potential risk to a fetus.
In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. 
Data
Animal Data
Lomustine was administered by intraperitoneal injection daily to pregnant rats during the period of organogenesis at dose levels of 0, 2, 4, 6, and 8 mg/kg.  Resorption rates and post-implantation loss occurred at doses greater than or equal to 4 mg/kg (approximately 0.18 times the clinical dose of 130 mg/m² based on BSA or approximately twice the total clinical dose of lomustine over 6 weeks). Malformations (omphalocele, ectopia cordis, scoliosis, syndactyly, hydrocephalus, microphthalmia, anophthalmia, anomalies of aortic arch, dextrocardia, malpositioning of the ovaries and testes, sternoschisis, and shortened/misshapen bone of the fore or hind limbs) and decreased fetal body weight occurred at all dose levels.  In pregnant rabbits treated with lomustine at 3 mg/kg (approximately 0.27 times the 130 mg/m² clinical dose based on BSA or approximately four times the total clinical dose of lomustine over 6 weeks) during organogenesis, there were increases in abortions and decreases in surviving pup weight that persisted postnatally.

Risk Summary
There is no information on the presence of lomustine or its metabolites in human milk, its effects on the breastfed infant, or its effects on milk production. Because of the potential for serious adverse reactions in breastfed infants from lomustine, advise women not to breastfeed during treatment with lomustine and for 2 weeks after the final dose.

Contraception
Females
Based on animal data and its mechanism of action, lomustine can cause fetal harm [see Use in Specific Populations (8.1)].  Advise females of reproductive potential to use effective contraception during treatment and for 2 weeks after the final dose.
Males
Based on lomustine’s mechanism of action, advise males with female partners of reproductive potential to use effective contraception during treatment with lomustine and for 3.5 months after the final dose [see Clinical Pharmacology (12.1)].
Infertility
Based on animal findings and its mechanism of action, lomustine may result in reduced fertility in males and females of reproductive potential [see Nonclinical Toxicology (13.1)].

Pediatric use, including dose, is not based on adequate and well-controlled clinical studies.

No data in the clinical studies of lomustine are available for patients 65 years of age and over to determine whether they respond differently than younger patients. Other reported clinical experience has not identified differences in responses between elderly and younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and of concomitant disease or other drug therapy.

Lomustine and its metabolites are known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and renal function should be monitored.

Lomustine alkylates DNA and RNA. As with other nitrosoureas, it may also inhibit several key enzymatic processes by carbamoylation of amino acids in proteins.

The pharmacodynamics of lomustine are unknown.

Distribution 
Lomustine crosses the blood-brain barrier.
Elimination
The serum half-life of lomustine metabolites ranges from 16 hours to 48 hours. 
Metabolism
Metabolic pathways involved in the elimination of lomustine have not been characterized.
Excretion
Following oral administration of radioactive lomustine at doses ranging from 30 mg/m² to 100 mg/m², approximately half of the radioactivity administered was excreted in the urine in the form of degradation products within 24 hours.
Specific Populations
The impact of patient specific (e.g., age, sex, and race) or disease (e.g., renal or hepatic impairment) characteristics on the pharmacokinetics of lomustine is unknown.

Lomustine is carcinogenic in rats and mice, producing a marked increase in tumor incidence in doses lower than those employed clinically.

In female rats, daily intraperitoneal treatment with lomustine for 2 weeks prior to mating with untreated males resulted in dose dependent decreases in number of corpora lutea and resorption rates with no live births at a dose of 3 mg/kg (approximately 0.14 times the recommended clinical dose of 130 mg/m² based on body surface area (BSA), or approximately twice the total clinical dose of lomustine over 6 weeks) and decreased pup survival during the first 4 postnatal days at doses greater than or equal to 1.5 mg/kg (a daily dose of approximately 0.06 times the recommended clinical dose of 130 mg/m² based on BSA or approximately equal to the total clinical dose of lomustine over 6 weeks). Lomustine may also result in decreased male fertility. Intraperitoneal injection of lomustine resulted in decreased fertility in male rats mated to untreated females based on decreased implantations and decreased fetal body weight at weekly doses greater than or equal to 5 mg/kg (approximately 0.23 times the single clinical dose of 130 mg/m² based on BSA, or approximately equal to the total clinical dose of lomustine over 6 weeks), and increased resorptions at doses greater than or equal to 2.5 mg/kg/week.

Lomustine Capsules, USP are available in three strengths, distinguishable by the color of the capsules, in individual bottles of 5 capsules each:

Store at 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature]. Avoid temperatures over 40°C (104°F).

Lomustine is a cytotoxic drug. Follow applicable special handling and disposal procedures.¹

To minimize the risk of dermal exposure, always wear impervious gloves when handling bottles containing lomustine capsules. Do not break lomustine capsules; avoid exposure to broken capsules. If dermal contact occurs, wash areas of skin contact immediately and thoroughly.