Mitomycin is an antibiotic medication approved by the Food and Drug Administration (FDA) for use in the systemic therapy of metastatic adenocarcinoma of the stomach or pancreas in combination with other drugs.[1] Mitomycin is also indicated for the treatment of bladder cancer, with maintenance doses of mitomycin proving effective for decreasing the tumor recurrence rate of low and intermediate-risk tumors.[2]

This medication is also indicated as a potential palliative treatment, especially when other treatments have failed. It also has approval for use as an adjunct to ab externo glaucoma surgery.[3] Due to raised intraocular pressure in the development of glaucoma, mitomycin is used during surgery to reduce postoperative scarring following a trabeculectomy or glaucoma drainage surgery.[4][3] However, its use in hepatic artery chemoembolization is yet to be approved by the FDA.

Mitomycin is an antibiotic that is isolated from the broth of Streptomyces caespitosus. This drug has demonstrated antitumor activity.[5][6] Mitomycin belongs to a group of alkylating agents that work by cross-linking the complementary strands found in DNA with absolute specificity and high efficiency for the CpG sequence.[3] 

Once activated by a reduction cascade, a series of spontaneous transformations cause mitomycin to attack DNA twice, resulting in cross-linking of strands of DNA double helix, thereby inhibiting DNA synthesis. Mitomycin is non-specific for a particular cell cycle phase but can exert its maximum effect in both the late G as well as the early S-phases.[6]

At higher concentrations, it also suppresses RNA and protein synthesis, hence being useful against some bacteria, spirochetes, and viruses. Lending to its toxic profile, mitomycin has a limited role as an antibiotic.[6] Mitomycin also causes chromosomal breaks, thus leading to shortened strands of DNA, which eventually leads to chromosomal damage; this property renders mitomycin as a potent carcinogen and teratogen.[3]

In glaucoma surgery, the antifibrotic property of mitomycin prevents tissue scarring when surgeons create a surgical ocular flap to relieve excess fluid buildup.[4]

Mitomycin administration is via the intravenous and intravesical routes. Subcutaneous or intramuscular administration is not advised or recommended. Close monitoring during intravenous infusions is advised, due to the high likelihood of extravasation. Signs of extravasation include poor blood return, pain, and swelling.[7]

Extreme caution is necessary to prevent extravasation as the drug is known to cause irritation, skin ulceration, and cellulitis. Given the cytotoxic nature of mitomycin, precautions, and procedures for handling, reconstitution, and disposal require strict adherence. It can be diluted up to a concentration of 40 micrograms per milliliter at room temperature in 5% dextrose, 0.9% sodium chloride, or sodium lactate injection. These solutions are stable and are to be used within 4 hours, 48 hours, or 24 hours, respectively.

In ophthalmology, topical administration is the only established route of administration.[3][4]

Bone marrow toxicity is the most commonly reported adverse effect, occurring in most of the patients treated with mitomycin in one study. It produces cumulative myelosuppression. Thrombocytopenia and possibly leukopenia may occur anytime within the first two months after beginning therapy, with an average duration of one month [8]. The recovery time after the termination of therapy was about ten weeks. About 25% of the leukopenic or thrombocytopenic episodes were permanent and did not return to baseline levels. As these patients are already immunocompromised, extreme caution is necessary to ensure further bone marrow suppression does not contribute to overwhelming subsequent infections.

Hemolytic uremic syndrome (HUS) has been observed in patients receiving systemic medication, with an incidence of <15% [1]. Patients presented with microangiopathic hemolytic anemia with fragmented red blood cells on peripheral blood smears. Patients with HUS also suffer the common and well-known side effects of the syndrome, including thrombocytopenia (≤100,000/mm) and renal failure (serum creatinine ≥1.6 mg/dL), which is irreversible. The use of blood product transfusions has correlated with exacerbation of the HUS symptoms. There is a high mortality rate of 52% associated with this syndrome.[9]

In another study, nausea, fever, vomiting, and anorexia occurred in up to 14% of people taking mitomycin. Alopecia and stomatitis occurred in up to 4% of individuals. Roughly 2% of the patients showed a statistically significant rise in creatinine. However, there was no correlation between the dose given or duration of therapy with the degree of renal impairment.[10]

Pulmonary toxicity has been infrequently reported, with patients presenting with dyspnea, nonproductive cough, and pulmonary infiltrates on radiologic imaging.[11] Vinca alkaloids, a common class of chemotherapeutic agents, also showed severe or life-threatening dyspnea and bronchospasm within minutes to hours of mitomycin administration.[10] Adult respiratory distress syndrome has also occurred in patients receiving mitomycin with other medications.[12] 

The most frequent adverse events with ocular administration of mitomycin occur locally and include blebitis, hypotony maculopathy, hypotony, endophthalmitis, cataract development, vascular reactions, and corneal reactions.[4]

Mitomycin is generally avoided and somewhat contraindicated in patients with a history of reactions to the drug, whether a hypersensitivity reaction or an idiosyncratic reaction. Its use is not recommended for patients with a high serum creatinine >1.7 mg/dL or creatinine clearance <30 mL/min. Other contraindications include coagulopathy, thrombocytopenia, or any bleeding diathesis.[8] Mitomycin should be avoided in patients with severe immunosuppression due to bone marrow suppression, including leukopenia and thrombocytopenia.