|March 26, 2016|
Cyclophosphamide (the generic name for Endoxan, Cytoxan, Neosar, Procytox, Revimmune), also known as cytophosphane, is a nitrogen mustard alkylating agent , from the oxazophorines group.
An alkylating agent adds an alkyl group (CnH2n+1) to DNA. It attaches the alkyl group to the guanine base of DNA, at the number 7 nitrogen atom of the imidazole ring.
The main use of cyclophosphamide is together with other chemotherapy agents in the treatment of lymphomas, some forms of leukemia. It is a chemotherapy drug that works by slowing or stopping cell growth.
Cyclophosphamide also decreases the immune system's response to various diseases and conditions. Therefore, it has been used in various non-neoplastic autoimmune diseases where disease-modifying antirheumatic drugs (DMARDs) have been ineffective. For example, systemic lupus erythematosus (SLE) with severe lupus nephritis (with trade name Revimmune).
A 2004 study
Cyclophosphamide is converted by mixed function oxidase enzymes in the liver to active metabolites. The main active metabolite is 4-hydroxycyclophosphamide, which exists in equilibrium with its tautomer, aldophosphamide. Most of the aldophosphamide is oxidised by the enzyme aldehyde dehydrogenase (ALDH) to make carboxyphosphamide. A small proportion of aldophosphamide is converted into phosphoramide mustard and acrolein. Acrolein is toxic to the bladder epithelium and can lead to hemorrhagic cystitis. This can be prevented through the use of aggressive hydration and/or mesna.
Recent clinical studies have shown that cyclophosphamide induce beneficial immunomodulatory effects in the context of adoptive immunotherapy. Although the mechanisms underlying these effects are not fully understood, several mechanisms have been suggested based on potential modulation of the host environment, including:
Thus, cyclophosphamide pre-conditioning of recipient hosts (for donor T cells) has been used to enhance immunity in na??ve hosts, and to enhance adoptive T cell immunotherapy regimens as well as active vaccination strategies, inducing objective anti-tumor immunity.
The main effect of cyclophosphamide is due to its metabolite phosphoramide mustard. This metabolite is only formed in cells that have low levels of ALDH.
Phosphoramide mustard forms DNA crosslinks between (interstrand crosslinkages) and within (intrastrand crosslinkages) DNA strands at guanine N-7 positions. This leads to cell death.
Cyclophosphamide has relatively little typical chemotherapy toxicity as ALDHs are present in relatively large concentrations in bone marrow stem cells , liver and intestinal epithelium. ALDHs protect these actively proliferating tissues against toxic effects phosphoramide mustard and acrolein by converting aldophosphamide to carboxyphosphamide that does not give rise to the toxic metabolites (phosphoramide mustard and acrolein).
Many people taking cyclophosphamide do not have serious side effects. Side-effects include chemotherapy-induced nausea and vomiting (CINV), bone marrow suppression, stomach ache, diarrhea, darkening of the skin/nails, alopecia (hair loss) or thinning of hair, changes in color and texture of the hair, and lethargy. Hemorrhagic cystitis is a frequent complication, but this is prevented by adequate fluid intake and Mesna (sodium 2-mercaptoethane sulfonate). Mesna is a sulfhydryl donor and binds acrolein.
Cyclophosphamide is itself carcinogenic, potentially causing transitional cell carcinoma of the bladder as a long-term complication. It can lower the body's ability to fight an infection. It can cause temporary or (rarely) permanent sterility.
Other (serious) side effects include:
Cyclophosphamide and the related nitrogen mustard-derived alkylating agent ifosfamide were developed by Norbert Brock and ASTA (now Baxter Oncology). Brock and his team synthesised and screened more than 1,000 candidate oxazaphosphorine compounds. They converted the base nitrogen mustard into a non-toxic "transport form". This transport form was a pro-drug, subsequently actively transported into the cancer cells. Once in the cells, the pro-drug was enzymatically converted into the active, toxic form.
The first clinical trials were published at the end of the 1950s.
GNU Free Documentation License. It uses material from the Wikipedia article "cyclophosphamide".
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