Behavior and resorption of mitomycin C following multiple intravesical administrations

Membranous nephropathy

Membranous nephropathy (MN) is a glomerular disease that can occur at all ages. In adults, it is the most frequent cause of nephrotic syndrome. In ~80% of patients, there is no underlying cause of MN (primary MN) and the remaining cases are associated with medications or other diseases such as systemic lupus erythematosus, hepatitis virus infection or malignancies. MN is an autoimmune disease characterized by a thickening of the glomerular capillary walls due to immune complex deposition. Identification of the phospholipase A2 receptor (PLA2R) as the major antigen in adults in 2009 induced a paradigm shift in disease diagnosis and monitoring and several other antigens have since been characterized. Disease outcome is difficult to predict and around one-third of patients will undergo spontaneous remission. In those at high risk of progression, immunosuppressive therapy with cyclophosphamide plus corticosteroids has substantially reduced the need for kidney replacement therapy. Owing to carcinogenic risk, other treatments (calcineurin inhibitors and CD20-targeted B cell depletion therapy (rituximab)) have been developed. However, disease relapses are frequent when calcineurin inhibitors are stopped and the remission rate with rituximab is lower than with cyclophosphamide, particularly in patients with high PLA2R antibody titres. Other new drugs are already available and antigen-specific immunotherapies are being developed.

Mitomycin C from birth to adulthood

Mitomycin C (MMC) intravesical therapy for "superficial" papillary bladder tumors was firstly introduced in the early seventies with promising results. In the following years, several pharmacokinetic studies investigated its mechanism of action to optimize the intravesical administration. Numerous studies confirmed thereafter both the ablative and the prophylactic efficacy and the low toxicity of MMC when intravesically given. In 1984, a complete response rate of 42% in 60 patients not responsive to thiotepa was reported with intravesical MMC at the dose of 40 mg diluted in 40 ml for 8 weeks. In the following decades, many large randomized studies showed the benefit of intravesical prophylaxis with MMC versus transurethral resection (TUR) alone. Since 2002, the role of adjuvant intravesical chemotherapy and of an early MMC instillation in preventing recurrence compared with TUR alone has been confirmed by large meta-analyses and stated by the European Association of Urology (EAU) guidelines. The need for further intravesical chemotherapy after the early instillation in patients at intermediate-high risk of recurrence has been proved by several trials. Although intravesical Bacillus Calmette-Guerìn (BCG) is considered the best choice for high-risk patients and MMC for the low-risk group, both MMC and BCG can be given to prevent recurrence in intermediate-risk patients. However, the higher efficacy of BCG over MMC is evident only if maintenance regimen is administered. Despite its proven efficacy, immediate intravesical MMC is not yet fully entered in common clinical practice and efforts should be made by the urologists to optimize its adoption.

[Hematogenous contact dermatitis after intravesicular instillation of mitomycin C]

Mitomycin C is an alkylating chemotherapeutic agent which is instilled intravesically to prevent recurrence of superficial bladder carcinomas. After several cycles of mitomycin C, our patient developed a pruritic genital dermatitis and palmar desquamation. Following exclusion of a fungal infection, we performed patch tests using the standard series, the major basic ointment ingredients, disinfectants, and mitomycin C in concentrations of 0.001 to 0.1%; the resulting diagnosis was allergic contact dermatitis due to delayed-type hypersensitivity to mitomycin C. The skin rash rapidly resolved with application of topical steroids, and the intravesical chemotherapy was changed to doxorubicin. Eczematous skin reactions are quite common side effects after intravesical instillation of mitomycin C. In the majority of cases, they are caused by delayed-type hypersensitivity reactions, presumably elicited by hematogenous spread of the allergen, and not by irritation. The sensitization most likely occurs via the bladder mucosa. In order to differentiate between allergic and toxic contact dermatitis, patch tests with the above-mentioned mitomycin C concentrations are useful. In cases of mild allergic contact dermatitis the intravesical chemotherapy might be continued with concomitant topical steroids.

Pharmacodynamics and pharmacokinetics of intravesical mitomycin C upon different dwelling times

The schedule in dosing of intravesical chemotherapy has thus far received little attention. Correlation of optimal contact time with bladder toxicity, as well as maximal chemotherapeutic effect for one of the drugs of first choice for intravesical instillation, i.e. mitomycin C (MMC), is a particularly important question. In a randomized study, we treated bladder cancer patients with intravesical MMC using 30-min and 60-min dwelling times. There were 28 evaluable patients in each of the 2 groups. The groups were comparable with respect to mean age, sex ratio and distribution of primary or recurrent and single or multiple tumors. Stages and grades of tumors were also comparable over both treatment groups. Pharmacokinetics of MMC and degradation/metabolism were monitored during the first 4 cycles and the last (8th) cycle using HPLC and mass spectrometry. Recurrence was significantly lower in the 60-min treatment group (35.7% vs. 14.3%, chi 2 test; 0.01 less than p less than 0.05). No recurrences were found in patients with Ta and T1 tumors when the 60-min dwelling time was used. Toxicity was mild and transient; the incidence was, surprisingly, lower in the 60-min group but the difference failed to reach the level of significance. Pharmacokinetics of systemic MMC and recovery in the urine was comparable over both groups and systemic absorption was calculated to be in the range of 1-5%.

Systemic allergic contact dermatitis from intravesical instillation of the antitumor antibiotic mitomycin C

6 cases of contact allergy to the antitumor antibiotic mitomycin C from intravesical instillation are described. Reports suggest that up to 9% of patients treated with mitomycin C for chemoresection/prevention of superficial bladder cancer will develop cutaneous side-effects. Patients may present either with vesicular dermatitis of the hands and feet and/or dermatitis of the genitals, or with more widespread eruptions. Probably most, if not all, skin reactions are caused by contact allergy. The distribution is suggestive of systemic contact dermatitis from mitomycin C absorbed from the vesical mucosa.

Chromatographic analysis of anticancer drugs

The present review on the methods for the analysis of anticancer drugs should be seen as an addition to the excellent work of Eksborg and Ehrsson published half a decade ago in this journal (Vol. 340, p.31). The style and format have been followed closely, with the focus again on chromatographic techniques. We felt it important to add a list of compound (group) structures as a service to the reader. Methods have been reviewed for alkylating agents, platinum compounds, antitumour antibiotics, antimetabolites, alkaloids, suramin, 1-hydroxy-3-amino-propylidene-1,1-bisphosphonate and tamoxifen.