The difference in pharmacokinetics of mitomycin C, given either as a single agent or as a part of combination chemotherapy

Polymer-lipid hybrid nanoparticles synchronize pharmacokinetics of co-encapsulated doxorubicin-mitomycin C and enable their spatiotemporal co-delivery and local bioavailability in breast tumor

Effective combination chemotherapy requires the delivery of drugs of synergism to tumor sites while sparing normal tissues. Herein we investigated whether coencapsulation of doxorubicin and mitomycin C within polymer-lipid hybrid nanoparticles (DMPLN) achieved this goal via ratiometric drugs in an orthotopic murine breast tumor model with nanocarrier-modified biodistribution, pharmacokinetics, local bioavailability and toxicity. Fluorescence imaging revealed quickened and extended tumor uptake but reduced cardiac accumulation of DMPLN. Quantitative drug analysis demonstrated prolonged systemic circulation, increased tumor accumulation and sustained synergistic ratios of doxorubicin and mitomycin C delivered by DMPLN over 24h. Higher levels of tumor cell apoptosis and reduced organ toxicity were obtained with DMPLN compared to free drug cocktails. DMPLN released DOX in tumors more efficiently than that from liposomal doxorubicin, as evidenced by a higher extent of the metabolite, doxorubicinol. These findings substantiate the importance of rational design of nanoparticles for synergistic drug combination therapy.

FROM THE CLINICAL EDITOR

The treatment of cancer usually involves using combination chemotherapeutic agents. In adopting a nanomedicine approach, one can in theory design combination therapy consisting of drugs of synergistic activities, with the aim to target tumor specifically while minimizing systemic toxicity. The authors in this study provided evidence for this rational design by co-encapsulation of doxorubicin and mitomycin C within polymer-lipid hybrid nanoparticles (DMPLN) in a breast cancer model.

Influence of cytokines, monoclonal antibodies and chemotherapeutic drugs on epithelial cell adhesion molecule (EpCAM) and LewisY antigen expression

MoAbs against tumour-associated antigens (TAA) may be useful for the treatment of colorectal cancer. Since an increased expression of TAA may lead to enhanced antibody-dependent cellular cytotoxicity we examined whether the cytokines IL-2, IL-4, IL-6, IL-10, IL-12, interferon-alpha (IFN-alpha), IFN-gamma, granulocyte-macrophage colony-stimulating factor, macrophage colony-stimulating factor and tumour necrosis factor-alpha can influence EpCAM and LewisY expression on the surface of the colorectal carcinoma cell lines HT29, LoVo and SW480. We found that only IFN-alpha increased significantly whereas IL-4 decreased both EpCAM and LewisY expression. IFN-gamma significantly increased LewisY expression only. When tumour cells were treated with MoAb, the LewisY-specific MoAb BR55-2 down-regulated LewisY antigen expression, whereas MoAb 17-1A, which binds to EpCAM, up-regulated this TAA after 3 days of culture. The cytokines IFN-alpha or IFN-gamma combined with MoAb 17-1A enhanced further slightly the expression of EpCAM. In additional experiments with chemotherapeutic drugs commonly used for the treatment of colorectal cancer, we found that 5-fluorouracil, mitomycin-C and oxaliplatin up-regulated EpCAM and LewisY antigen expression. Raltitrexed enhanced LewisY and down-regulated EpCAM expression, whereas CPT-11 had no influence at all. The highest expression for EpCAM on HT29 cells was achieved by the combination of IFN-alpha, 5-fluorouracil and MoAb 17-1A. Our results may be useful for defining combinations of biological and chemotherapeutic drugs for the treatment of colorectal cancer. Further trials should evaluate to what extent these combinations enhance antibody-dependent cellular cytotoxicity.

Pharmacokinetic characteristics of 5-fluorouracil and mitomycin C in intraperitoneal chemotherapy

Eight patients with malignancies confined to the peritoneal space participated in this study. Five hundred milligrams 5-fluorouracil or 10 mg mitomycin C was diluted in 1 L saline. The mixed solution was injected intraperitoneally through the semi-permanent peritoneal catheter. Blood and peritoneal fluid were collected after injection. 5-Fluorouracil concentrations in the peritoneal fluid were 1000 times those in serum, while mitomycin C concentrations were 100 times those in serum. Areas under the concentration vs time curve (AUC) were calculated by the trapezoidal method with extrapolation to infinity. The ratio of peritoneal fluid AUC to serum AUC was about 1400 for 5-fluorouracil and 80 for mitomycin C. Patterns for the absorption and elimination from systemic circulation were similar for both compounds. Drug concentrations in the peritoneal fluid and serum were analysed according to the compartment model. The half-life in the peritoneal fluid (t1/2p) and the rate constant from the peritoneal fluid to the systemic circulation (ka) were nearly equal for both 5-fluorouracil and mitomycin C (t1/2p, 1.0 h for 5-fluorouracil and 1.3 h for mitomycin C; ka 0.71 h-1 for 5-fluorouracil and 0.68 h-1 for mitomycin C), although the apparent volume of distribution (Vds/F) and clearance in the peritoneal cavity (CLp) for mitomycin C (78 L m-2 and 1.8 L h-1 m-2) were about twice the values for 5-fluorouracil (149 L m-2 and 0.8 L h-1 m-2).

Pharmacokinetics of BW12C and mitomycin C, given in combination in a phase 1 study in patients with advanced gastrointestinal cancer

The effect of combining the oxygen-transport-modifying drug BW12C with mitomycin C was investigated in a phase 1 study of 26 patients with advanced gastrointestinal cancer. The dose of BW12C was increased from 20 mg/kg to 60 mg/kg. Dose-limiting toxicity of vomiting was experienced at doses greater than 50 mg/kg. This corresponded to whole blood levels > or = 700 micrograms/ml and to > 50% haemoglobin modification. Whole blood concentrations of BW12C and modification of the haemoglobin oxygen saturation curve were linearly dependent on dose. BW12C whole blood pharmacokinetics were best described by a one-compartment model and were clearly dose-dependent. The half-life increased from 2.1 h at a dose of 20 mg/kg to 7.2 h at a dose of 60 mg/kg. The AUC increased in a similar non-linear fashion with increasing dose. Mitomycin C was given at a fixed dose of 20 mg/m2 at the end of the BW12C infusion. Mitomycin C plasma pharmacokinetics fitted a two-compartment model, giving a mean beta half-life of 50 +/- 7 min and AUC of 1.1 +/- 0.08 micrograms/ml h, and were unaffected by the combined treatment. There was no evidence of increased mitomycin C toxicity.

Pharmacokinetic study of mitomycin C with emphasis on the influence of aging

Mitomycin C (MMC) at a dose of 8 mg/m2 was administered by short intravenous infusion to 14 cancer patients. All patients had normal renal, hepatic, cardiac and bone marrow functions. The plasma level of MMC, which was determined by high-performance liquid chromatography over a 24-h period after the infusion, fitted the 2-compartment model curve except for one patient. There was a significant correlation between the area under the time versus concentration curve (AUC) of MMC and the age of patients (r = 0.558, P < 0.05). Pharmacokinetic parameters in one of the older (a 69-year-old male) patients were extremely different from those of the other 13 patients. This patient experienced severe myelosuppression, probably due to the markedly increased AUC of MMC. Our results suggest that a patient's age has a significant influence on the pharmacokinetics of MMC in patients with normal major organ functions and that in some patients, MMC pharmacokinetics may be altered, possibly due to interpatient variation in the activation or metabolic pathway of MMC.

The pharmacokinetic plasma profile of mitomycin C, measured after sequential intermittent intravenous administration

The pharmacokinetic plasma profile of mitomycin C (MMC) was studied during sequential courses in man. MMC was given repeatedly as i.v. bolus injections at fixed dose levels to the same patient either as a single agent or as part of different combination chemotherapy regimens. Large interindividual variations between the various pharmacokinetic parameters were observed. Statistical analysis showed no significant differences between average pharmacokinetic parameters when comparing the first and the second MMC injection, except for the total body clearance (Cltot). The Cltot was higher for the second injection when compared to the first injection in a group of patients who received MMC as a single agent (10 patients). For a group of patients receiving MMC as part of a combination therapy the average values of Cltot of the first when compared to the second injection were not statistically different (nine patients). This observation could not be correlated with clinical observations on toxicities.