DNA Alkylator

Lomustine inhibits ZR-75-1 and U373 from growing, with IC50 values of 12 μM and 15 μM, respectively. Lomustine inhibits the expression of O6-alkylguanine-DNA alkyltransferase, a DNA repair protein. [1] In both medulloblastoma and normal human epithelial and fibroblast cells, lomustine (420 μM) induces apoptosis via the mitochondrial pathway by lowering the levels of the anti-apoptosis proteins Bcl-2 and Bcl-xl, respectively. In medulloblastoma cells, locustrine causes a cell cycle delay in the G2/M phase; in HFSN1 cells, locustrine upregulates the level of the protein p21 in a p53-independent manner. [2]

Lomustine may result in irreversible, delayed, cumulative dose-related chronic hepatotoxicity that may be fatal. [4] In cats with spontaneously arising tumors, lomustine may occasionally cause severe hematological toxicity; grade III or IV neutropenia and thrombocytopenia have an incidence of 4.1% and 1.0%, respectively. In cats with spontaneously arising tumors, locustin tends to increase the risk of progressive neutropenia and statistically significant higher response rates. [5]

Cell lines are commonly grown as monolayers in DMEM supplemented with glutamine, penicillin/streptomycin, 10% foetal calf serum, and 25 mm HEPES. Studies on cytotoxicity are conducted in an atmosphere with 5% CO₂ in a medium free of HEPES. In 96-well plates, 750–1000 cells/well are plated, and after an overnight incubation, they are treated for two hours either with or without 33 μM BG. In the same medium, temozolomide or CCNU is then added for an hour, with a final DMSO concentration of no more than 1%. Growth studies reveal that the cells are in log phase growth during the assay period. The cells are then cultured for an additional 7 days in fresh medium before being tested for protein content using the NCI sulphorhodamine assay. Cells are treated consecutively for 24 hours with fresh medium every day as part of the repeated temozolomide dosing schedule. At least two assays are performed.

Mice: During the study, groups of eight B6C3F1 mice each receive PBS or 5-FC as the sole control. A single dose of 30 mg/kg of locustine is given to one group of mice (Lomustine Day 1 + PBS) on day 1, along with six cycles of PBS (800 μL/day, BID for four days in a row every ten days). For four days in a row, the remaining mice are given 5-FC (500 mg/kg/dose, IP, BID) along with either Lomustine on day one (Lomustine (CCNU) Day 1 + 5-FC) or Day 43 (Lomustine (CCNU) Day 43 + 5-FC for maximum benefit. Six cycles of four days on, ten days off, five FC, or five PBS are completed. When the final 5-FC treatment is completed, each experiment comes to an end. Every tissue is gathered and stored for pathology analysis.
Rats: Rat groups (n = 8 per group) are only given PBS or 5-FC as controls during the study. Rats in the Lomustine (CCNU) Day 1 + PBS group are given a single dose of 30 mg/kg of Lomustine on day 1 and six cycles of PBS (8 mL/day, BID). For five days in a row, the remaining rats are given 5-FC (500 mg/kg/dose, IP, BID) plus either Lomustine on Day 1 (Lomustine (CCNU) Day 1 + 5-FC) or Day 22 (Lomustine (CCNU) Day 22 + 5-FC), after which they are given two days off medication. A total of six repetitions of the 5-day on, 2-day off 5-FC or PBS cycle are made[3].

Absorption, Distribution and Excretion
Well and rapidly absorbed from the gastrointestinal tract.
Following oral administration of radioactive CeeNU at doses ranging from 30 mg/m2 to 100 mg/m2, about half of the radioactivity given was excreted in the urine in the form of degradation products within 24 hours.
Lomustine is excreted primarily in the urine as metabolites. Following oral administration of (14)C-labeled lomustine, about 50% of the radioactivity is excreted within 12 hr and about 75% within 4 days.
Lomustine is reported to be widely distributed. Lomustine and/or its metabolites cross the blood-brain barrier and are rapidly transported into cells due to their high lipid solubility. Although intact lomustine is not detectable in the CSF, active metabolites of the drug appear in substantial concentrations within 30 minutes after oral administration of lomustine. CSF concentrations of metabolites have been reported to be 15-50% or greater than concurrent plasma concentrations. Lomustine metabolites are present in milk, but in concentrations than those in maternal plasma.
Lomustine is rapidly absorbed from the GI tract; the drug is also absorbed following topical application. Peak plasma concentrations of metabolites occur within 1-6 hours following administration of an oral dose of lomustine.
Following its ip or iv injection or oral administration, (14)C-labelled CCNU was rapidly distributed to many tissues in mice, rats, rabbits and dogs.. About 80% of label was excreted in the urine of mice 24 hours after a single parenteral or oral dose of 50 mg/kg bw.

---

Metabolism / Metabolites
Hepatic. Rapid and complete, with active metabolites.
CCNU undergoes spontaneous decomposition under physiological conditions to release both alkylating and carbamoylating entities. It disappears from plasma within 5 minutes following its oral administration, but the antitumor effect of its metabolites may persist for up to 15 minutes. ... In addition to chemical decomposition, CCNU may be converted by microsomal metabolism to 6 isomeric hydroxylated derivatives, some of which may differ in their biological properties from CCNU.
Virtually all of a dose of lomustine is metabolized within 1 hour after oral administration. The half-life of lomustine metabolites is biphasic; although the initial plasma half-life is 6 hours, the second phase plasma half-life is 1-2 days, and 15-20% of the metabolites remain in the body 5 days after administration of lomustine. Prolongation of plasma concentrations is thought to reflect a combination of protein binding and enterohepatic circulation of metabolites.
Hepatic. Rapid and complete, with active metabolites.
Route of Elimination: Following oral administration of radioactive CeeNU at doses ranging from 30 mg/m2 to 100 mg/m2, about half of the radioactivity given was excreted in the urine in the form of degradation products within 24 hours.
Half Life: Approximately 94 minutes, however the metabolites have a serum half-life of 16 to 48 hours.

---

Biological Half-Life
Approximately 94 minutes, however the metabolites have a serum half-life of 16 to 48 hours.
The half-life of lomustine metabolites is biphasic; although the initial plasma half-life is 6 hours, the second phase plasma half-life is 1-2 days, and 15-20% of the metabolites remain in the body 5 days after administration of lomustine.

Toxicity Summary
Lomustine is a highly lipophilic nitrosourea compound which undergoes hydrolysis in vivo to form reactive metabolites. These metabolites cause alkylation and cross-linking of DNA (at the O6 position of guanine-containing bases) and RNA, thus inducing cytotoxicity. Other biologic effects include inhibition of DNA synthesis and some cell cycle phase specificity. Nitrosureas generally lack cross-resistance with other alkylating agents. As lomustine is a nitrosurea, it may also inhibit several key processes such as carbamoylation and modification of cellular proteins.

---

Hepatotoxicity
Mild and transient elevations in serum aminotransferase or alkaline phosphatase levels are found in a high proportion of patients treated antineoplastic regimens that include lomustine. The abnormalities are generally transient, do not cause symptoms and do not require dose modification. Clinically apparent liver injury from lomustine has been described, but is uncommon. The pattern of serum enzyme elevations were described as cholestatic and onset was after 3 to 4 months of therapy, but otherwise its clinical characteristics have not been clearly characterized. Lomustine is often given in combination with other antineoplastic agents, many of which are also hepatotoxic, so the effect of lomustine in causing liver injury is often difficult to assess. Lomustine has not been associated specifically with sinusoidal obstruction syndrome, but it is not generally given in high doses or used for myeloablation in preparation for bone marrow transplantation, the situations in which this syndrome generally occurs.
Likelihood score: D (possible cause of clinically apparent liver injury).

---

Protein Binding
50%

---

Toxicity Data
Oral, rat: LD₅₀ = 70 mg/kg. Pulmonary toxicity has been reported at cumulative doses usually greater than 1,100 mg/m2. There is one report of pulmonary toxicity at a cumulative dose of only 600 mg. The onset of toxicity has varied from 6 months after initiation of therapy, to as late as 15 years after.

---

Interactions
The combined action of the antitumor antibiotic bleomycin and chloroethylnitrosourea was studied in human lymphocytes in vitro. All the experiments were carried out with 20 ug/mL bleomycin for a given treatment time. By adding 0.7 and 3.5 ug/mL chloroethylnitrosourea at late G1-S phase we have demonstrated a considerable increase in both percent of aberrant cells and production of dicentrics and rings (5-fold, p < 0.001). At late S-G2 the combined treatment led to a significant enhancement of breaks per cell (p < 0.0001) and cells with more than 12 aberrations. A possible explanation could be the known repair inhibitory potential of chloroethylnitrosourea, but its pure clastogenic action still has to be considered. The results presented here point out the need for seeking chemotherapeutic regimens with reduced concentrations of the drugs in combination.
Three patients developed the sudden onset of total blindness several months after treatment with oral CCNU and low dose whole brain radiation. The anterior visual system was included in the radiation field in all patients. Radiotherapy was given for a frontal lobe glioblastoma multiforme, for central nervous system prophylaxis in a patient with oat cell carcinoma of the lung, and for a parietal lobe glioblastoma multiforme. None of the neoplasms involved the anterior visual system. The radiation dose ranged from 3000 to 4650 rad and the oral CCNU dosage from 300 mg to 1050 mg. Patients 1 and 2 also received other chemotherapeutic agents. Patient 3 who was treated only with oral CCNU and cranial irradiation died. At autopsy the brain showed a widely infiltrating residual high grade glioma as well as patchy coagulative necrosis with swollen axons and dystrophic calcifications. The optic chiasm showed severe demyelination, axonal loss, and hyalinized vessels. Synergism between oral CCNU and radiation may account for the blindness produced.

---

Non-Human Toxicity Values
LD50 Rat oral 70 mg/kg
LD50 Rat ip 50,350 ug/kg
LD50 Mouse female oral 38 mg/kg bw
LD50 Mouse male oral 51 mg/kg
For more Non-Human Toxicity Values (Complete) data for LOMUSTINE (7 total), please visit the HSDB record page.

[1]. Br J Cancer . 1993 Jun;67(6):1299-302.

[2]. J Neurooncol . 2008 Apr;87(2):123-32.

[3]. J Vet Intern Med . 1999 Nov-Dec;13(6):601-5.

1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) (Lomustine) can cause cancer according to an independent committee of scientific and health experts. It can cause developmental toxicity according to state or federal government labeling requirements.
Lomustine is an N-nitrosourea that is urea in which one of the nitrogens is substituted by a 2-chloroethyl group and by a nitroso group, while the other nitrogen is substituted by a cyclohexyl group. An alkylating antineoplastic agent, it is used in the treatment of brain tumours, lung cancer, malignant melanoma and other solid tumours. It has a role as an alkylating agent and an antineoplastic agent. It is a member of N-nitrosoureas and an organochlorine compound.
An alkylating agent of value against both hematologic malignancies and solid tumors.
Lomustine is an Alkylating Drug. The mechanism of action of lomustine is as an Alkylating Activity.
Lomustine is an orally administered alkylating agent used alone and in combination with other antineoplastic agents in the treatment of several malignancies including Hodgkin disease, lymphoma, and brain cancer. Lomustine therapy is associated with minor transient serum enzyme elevations and has been linked to rare cases of clinically apparent acute liver injury.
Lomustine is a nitrosourea with antineoplastic activity. Lomustine alkylates and crosslinks DNA, thereby inhibiting DNA and RNA synthesis. This agent also carbamoylates DNA and proteins, resulting in inhibition of DNA and RNA synthesis and disruption of RNA processing. Lomustine is lipophilic and crosses the blood-brain barrier. (NCI04)
Lomustine is only found in individuals that have used or taken this drug. It is an alkylating agent of value against both hematologic malignancies and solid tumors. Lomustine is a highly lipophilic nitrosourea compound which undergoes hydrolysis in vivo to form reactive metabolites. These metabolites cause alkylation and cross-linking of DNA (at the O6 position of guanine-containing bases) and RNA, thus inducing cytotoxicity. Other biologic effects include inhibition of DNA synthesis and some cell cycle phase specificity. Nitrosureas generally lack cross-resistance with other alkylating agents. As lomustine is a nitrosurea, it may also inhibit several key processes such as carbamoylation and modification of cellular proteins.
An alkylating agent of value against both hematologic malignancies and solid tumors.

---

Drug Indication
For the treatment of primary and metastatic brain tumors as a component of combination chemotherapy in addition to appropriate surgical and/or radiotherapeutic procedures. Also used in combination with other agents as secondary therapy for the treatment of refractory or relapsed Hodgkin's disease.

---

Mechanism of Action
Lomustine is a highly lipophilic nitrosourea compound which undergoes hydrolysis in vivo to form reactive metabolites. These metabolites cause alkylation and cross-linking of DNA (at the O6 position of guanine-containing bases) and RNA, thus inducing cytotoxicity. Other biologic effects include inhibition of DNA synthesis and some cell cycle phase specificity. Nitrosureas generally lack cross-resistance with other alkylating agents. As lomustine is a nitrosurea, it may also inhibit several key processes such as carbamoylation and modification of cellular proteins.
Although lomustine is believed to act by alkylation, the mechanism of action has not been completely elucidated, and other effects as carbamoylation and modification of cellular proteins may be involved. The overall result is thought to be the inhibition of both DNA and RNA synthesis.

---

Therapeutic Uses
Antineoplastic Agents, Alkylating
CeeNU has been shown to be useful as a single agent in addition to other treatment modalities, or in established combination therapy with other approved chemotherapeutic agents in the following: Brain tumors-both primary and metastatic, in patients who have already received appropriate surgical and/or radiotherapeutic procedures. Hodgkin's Disease-secondary therapy in combination with other approved drugs in patients who relapse while being treated with primary therapy, or who fail to respond to primary therapy. /Included in US product label/
Antineoplastic agent. The compound has had limited use since the early 1970s in the treatment of Hodgkin's disease and various solid tumors. These include primary and metastatic brain tumors, colorectal tumors, and certain pulmonary malignancies. It is usually used in conjunction with other antineoplastic drugs.
Although lomustine is labeled for use in combination with other agents as secondary therapy for the treatment of refractory or relapsed Hodgkin's disease, combination regimens containing other agents currently are preferred for this cancer. /Included in US product label/
For more Therapeutic Uses (Complete) data for LOMUSTINE (8 total), please visit the HSDB record page.

---

Drug Warnings
/BOXED WARNING/ WARNINGS: CeeNU (lomustine) should be administered under the supervision of a qualified physician experienced in the use of cancer chemotherapeutic agents. Bone marrow suppression, notably thrombocytopenia and leukopenia, which may contribute to bleeding and overwhelming infections in an already compromised patient, is the most common and severe of the toxic effects of CeeNU. Since the major toxicity is delayed bone marrow suppression, blood counts should be monitored weekly for at least 6 weeks after a dose. At the recommended dosage, courses of CeeNU should not be given more frequently than every 6 weeks. The bone marrow toxicity of CeeNU is cumulative and therefore dosage adjustment must be considered on the basis of nadir blood counts from prior dose
Because some lomustine metabolites are present in milk, women receiving the drug probably should not nurse their infants.
Delayed onset of pulmonary fibrosis occurring up to 17 years after treatment has been reported in patients receiving related nitrosoureas combined with cranial radiation therapy for intracranial tumors during childhood and adolescence (age 1-16 years). Late onset of reduction in pulmonary function was observed in all long-term survivors. Nitrosourea-induced pulmonary fibrosis may be slowly progressive and can cause death.
Nausea and vomiting occur in 45-100% of patients within 45 min to 6 hr after ingestion of an oral dose of lomustine. Although these symptoms are not severe and usually abate within 24 hr, they may persist up to 36 hr and are often followed by 2-3 days of anorexia. Stomatitis has occurred infrequently.
For more Drug Warnings (Complete) data for LOMUSTINE (25 total), please visit the HSDB record page.

---

Pharmacodynamics
Lomustine is an alkylating agent of the nitrosourea type. Lomustine and its metabolites interferes with the function of DNA and RNA. It is cell cycle–phase nonspecific. Cancers form when some cells within the body multiply uncontrollably and abnormally. These cells then spread and destroy nearby tissues. Lomustine acts by slowing this process down. It kills cancer cells by damaging the DNA (the genetic material inside the cells) and stops them from dividing.

C9H16CLN3O2

233.69524

233.093

C, 46.26; H, 6.90; Cl, 15.17; N, 17.98; O, 13.69

13010-47-4

3950

Light yellow to yellow solid powder

1.4±0.1 g/cm3

88-90

0.00142mmHg at 25°C

1.583

2.76

1

3

3

15

219

0

O=C(NC1CCCCC1)N(CCCl)N=O

GQYIWUVLTXOXAJ-UHFFFAOYSA-N

InChI=1S/C9H16ClN3O2/c10-6-7-13(12-15)9(14)11-8-4-2-1-3-5-8/h8H,1-7H2,(H,11,14)

1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea

NSC 79037; NSC-79037; NSC79037; Lomustinume. CeeNU; Belustin; Belustine; Cecenu; Citostal; Lomeblastin; Lucostin; Lucostine; Prava; CCNU; RB1509; WR139017

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: ≥ 100 mg/mL (~427.9 mM)
H2O: < 0.1 mg/mL

Solubility in Formulation 1: ≥ 2.5 mg/mL (10.70 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: ≥ 2.5 mg/mL (10.70 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 2.5 mg/mL (10.70 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

Solubility in Formulation 4: 30%propylene glycol+ 5%Tween 80+ 65%D5W, pH 4: 10.0mg/ml (42.79mM)

---

 (Please use freshly prepared in vivo formulations for optimal results.)