INTRAVESICAL CHEMOTHERAPY

Multidrug resistance in a urothelial cancer cell line after 3, 1-hour exposures to mitomycin C

PURPOSE

The development of multidrug resistance is a problem in chemotherapy for many tumors. In vitro models of multidrug resistance require adapted cell strains that are conventionally produced from parental lines by chronic low dose drug exposure. Because adjunctive intravesical chemotherapy for superficial bladder cancer uses short courses of high dose treatment, we investigated whether such exposure of the RT112 cell line (Catalogue No. ACC 418, Deutsche Sammlung von Mikroorganismen und Zellkulturen, Braunschweig, Germany) to mitomycin C, which is a common intravesical agent, would elicit multidrug resistance.

MATERIALS AND METHODS

Three 1-hour exposures to graded concentrations were done at 3-week intervals. The highest mitomycin C concentrations permitting recovery in cultures and, therefore, available for examination were 3.13 and 1.06 microg/ml. Cross-resistance to epirubicin in surviving cultures was visualized by confocal microscopy and quantified by MTT residual viable biomass assay. Spheroids were made by the agarose technique and exposed to high dose mitomycin C to assess the probability that the relevant concentrations might be found clinically in some cell layers of a superficial lesion.

RESULTS

Resistance was induced by 3 short drug exposures. The evidence for this was functional (MTT assay) and by intracellular localization. Toxicity to an alternative multidrug resistance class drug was lowered in surviving clones and nuclear exclusion of the drug was noted. Spheroid experiments showed sharp gradients of incorporated drug across the outermost layers of cells, suggesting that a proportion of cells in clinical superficial bladder cancer would be exposed to drug at concentrations that generated the resistant clones in these experiments.

CONCLUSIONS

We report multidrug resistance induction using 2 independent methodologies. The results have implications for the development of experimental models and the likelihood of resistance resulting from clinical regimens. Brief exposure can elicit detectable resistance. It is arguable that selective rather than instructive mechanisms are involved, and the levels of drug required are likely to exist in a superficial transitional cell carcinoma frond exposed at its surface to high drug concentrations.

The nuclear membrane in multidrug resistance: microinjection of epirubicin into bladder cancer cell lines

OBJECTIVE

To assess whether microinjecting epirubicin into cells showing multidrug resistance (MDR, common to many cancers, including bladder cancer, with resistance to, e.g. anthracyclines and mitomycin C) spares the nucleus, as when these drugs accumulate, distribution in MDR cells characteristically spares the nucleus, suggesting that the nuclear membrane is responsible for excluding cytotoxic drugs from MDR nuclei.

MATERIALS AND METHODS

Nuclear exclusion of drugs is an important feature of resistance in MDR cells, as many MDR-susceptible drugs have cytotoxic actions within the nucleus. Drug accumulation in 'classical' P-glycoprotein-mediated MDR cells is greatly reduced by efflux. Microinjection of epirubicin into the cytoplasm of MDR cells bypasses the P-glycoprotein efflux pump on the plasma membrane. Nuclear sparing would directly implicate the nuclear membrane in this phenomenon. Because of their fluorescence properties, which allow study by confocal microscopy and flow cytometry, anthracyclines have also been used extensively to investigate MDR. Thus sensitive (MGH-U1 and RT112) and MDR (MGH-U1R and MGH-U1-MMC) bladder cancer cell lines were used. Adherent cells from each cell line were individually microinjected with epirubicin (0.5 mg/mL) and a 77 kDa fluorescein isothiocyanate (FITC)-dextran (0.5 mg/mL). The pattern of nuclear epirubicin uptake in injected cells was then evaluated by confocal microscopy. The 77 kDa FITC-dextran allowed easier identification of injected cells and was also excluded from their nuclei.

RESULTS

Sensitive bladder cancer cell lines all showed a nuclear accumulation pattern of epirubicin, consistent with their normal uptake after exposure to epirubicin. The MDR cell lines showed the characteristic nuclear-sparing pattern of epirubicin uptake, similar to the normal uptake pattern after epirubicin exposure. The 77 kDa FITC-dextran showed clearly which cells had been microinjected, and was excluded from the nuclei of all injected cells. Cell viability was confirmed by acridine-orange staining after initial visualization of injected cells.

CONCLUSION

The nuclear membrane is responsible for the nuclear exclusion of epirubicin in MDR cells. Further work is necessary to determine the mechanisms involved.

A phase I study of intravesical suramin for the treatment of superficial transitional cell carcinoma of the bladder

PURPOSE

Suramin is a polysulfonated naphthylurea that inhibits proliferation and DNA synthesis of transitional cell carcinoma cell lines. Its large molecular size and negative charge inhibit bladder absorption, making suramin an excellent candidate for intravesical chemotherapy. Intravesical suramin was evaluated in a phase I study to define dose limiting toxicity and systemic absorption, determine a starting dose and regimen for phase II studies and provide a preliminary assessment of in vivo antitumor activity.

MATERIALS AND METHODS

Intravesical suramin treatment was administered in 9 patients with histologically identified transitional cell carcinoma (Tcis, Ta or T1) in whom at least 1 course of standard intravesical chemotherapy (bacillus Calmette-Guerin, thiotepa or mitomycin C) had failed. Suramin was administered once weekly for 6 weeks. Patients were treated in groups of 3 using a 60 cc volume and intrapatient dose escalation schedule. Suramin doses of 0.3 to 614.4 mg./ml. were administered intravesically. The last group was treated with the same weekly dose for 6 weeks.

RESULTS

The 9 patients underwent 54 treatments with suramin. Plasma suramin concentration after treatment was 1.9 to 38.0 microg./ml. and was not related to treatment dose. The dose escalation phase was limited by the solubility of suramin in solution. Complications included self-limited bladder spasms (less than 24 hours) in 4 of 54 treatments (7%) and new or worsening vesicoureteral reflux in 3 ureters (17%). Another patient who was treated after the Foley balloon was inflated in the urethra experienced bladder spasms, skin flushing and fever (39C). Mean bladder capacity before and after treatment was 600 and 540 ml., respectively. At followup 7 patients had stage Ta tumors and 2 had carcinoma in situ.

CONCLUSIONS

An intravesical suramin dose of 153 mg./ml was defined as a safe treatment parameter with acceptable plasma concentrations and minimal side effects. Phase II studies are needed to assess the antitumor activity of suramin in patients with transitional cell carcinoma of the bladder.

Intravesical pH: a potentially important variable affecting efficacy and the further development of anthracycline chemotherapy for superficial bladder cancer

OBJECTIVE

To assess, using epirubicin-sensitive and multidrug resistant (MDR) derivatives of human bladder cancer cell lines in vitro, the probable effect of intravesical pH changes, with and without the MDR antagonist verapamil, on the uptake, intracellular distribution and cytotoxicity of epirubicin during intravesical chemotherapy.

MATERIALS AND METHODS

Incubations for cytotoxicity testing were carried out in buffered medium containing epirubicin, at pH values of 6.0-8.5, with verapamil where appropriate. The cytotoxicity of epirubicin, with and without verapamil, was determined using the tetrazolium cytotoxicity assay. Intracellular epirubicin fluorescence was assessed using flow cytometry and confocal microscopy. Flow cytometric total intracellular epirubicin fluorescence was measured at pH 6.0, 6.4, 6.8, 7.2, and 7.6, and confocal microscopy was carried out at pH 6.0 and 8.0. The MDR-reversing agent verapamil was added at 100 micro g/mL to some incubations.

RESULTS

Epirubicin cytotoxicity in resistant cell lines appears considerably enhanced by adding verapamil and further improved, especially in MDR cells, by alkalinization of the drug solution to pH 8.0. Flow cytometry results showed striking and consistent differences in epirubicin handling with pH. Sensitive cells can be induced to absorb considerably more drug at alkaline pH, whilst resistant cells show no such behaviour. Nuclear drug fluorescence was greater in sensitive cells at alkaline pH, but cytoplasmic drug fluorescence in the resistant cells was little changed by pH. Adding verapamil to resistant cells restored the sensitive phenotype of drug handling.

CONCLUSION

Buffering epirubicin to an alkaline pH before intravesical application should increase its intrinsic cytotoxicity. The potential for synergy at certain drug combinations will be enhanced by applying these findings. MDR reversal and fatty acid augmentation of drug uptake are discussed as examples.

Reduced cellular transport and activation of fluoropyrimidine nucleosides and resistance in human lymphocytic cell lines selected for arabinosylcytosine resistance

Arabinofuranosylcytosine (araC) resistant H9-araC0.05 and H9-araC0.5 sublines were obtained following in vitro exposure of H9 cells to 0. 05 and 0.5 microM araC, respectively. These cell lines were 83.3- and 266.7-fold, 21- and 80-fold, and 2.4- and 4.0-fold more resistant to 5-fluorouridine (FUR), 5-fluoro-2'-deoxyuridine (FdUR), and 5-fluorouracil (FU), respectively. Compared with H9 cells, the cellular accumulation of FUR was 2.2 and 0.2%, FdUR 15.6 and 0.9%, and FU 56.9 and 66.5% in H9-araC0.05 and H9-araC0.5 cells, respectively. An araC resistant HL60 cell line (promyelocytic cell line) was 5.0- and 1.7-fold resistant to FUR and FdUR, respectively, but displayed no resistance to FU. The lower FUR and FdUR nucleotide levels in the resistant cells were a result of reduced cellular transport and uridine kinase (UR kinase) and thymidine kinase (TK) activities. Compared with the parental cell line, the p-nitrobenzyl thioinosine (an inhibitor of nucleoside transport) binding sites also were lower in the araC resistant cells. There was no difference in the expression of multidrug-resistant protein and thymidylate synthase mRNA in the parental and the resistant cell lines. Data presented here suggest that araC exposure of H9 cells, in addition to araC resistance, induced/selected cells that were resistant to FUR and FdUR. These cells had altered cellular drug transport and lower TK and UR kinase activities. Further studies to understand molecular mechanisms of this phenomenon are warranted.

An overview of the treatment of superficial bladder cancer. Intravesical chemotherapy

Superficial bladder cancer accounts for approximately 70% to 80% of all newly diagnosed bladder cancers. The vast majority of these cancers are transitional bladder tumors of various histologic grades (I to III). Superficial tumors include carcinoma in situ (CIS), tumors confined to the epithelium (Ta), and superficial tumors that invade the lamina propria (T1) but do not involve superficial muscle layers. The primary treatment for eradication of stage Ta and T1 bladder cancers is transurethral resection of the tumor. Many patients with superficial bladder tumors treated with endoscopic surgery alone have recurrence or tumor progression at some point in their follow-up, and, in these patients, the need for adjuvant treatment becomes a major concern.

Asymptomatic microscopic hematuria--is investigation necessary?

Microscopic hematuria is common in asymptomatic adults, but the benefit of screening the general population for blood in the urine has not been established. On the other hand, most studies of referred patients with putatively asymptomatic microscopic hematuria have reported a 2-11% prevalence of urothelial malignancies, leading to the recommendation that all patients with microscopic hematuria be thoroughly investigated. Urinalysis is inexpensive and highly acceptable to the general population, but is neither a sensitive, nor specific test, and has poor predictive value for urothelial malignancies, and nephrological diseases. Furthermore the benefits of early detection of such diseases has not been established. We conclude that screening urinalysis cannot be recommended. Studies are needed to determine which constellation of findings primary physicians use to select patients for referral to centers with urological and nephrological expertise.

Treatment of superficial bladder cancer with intravesical chemotherapy

Proper care of patients with superficial bladder cancer requires the assessment of multiple factors, including an understanding of the natural history of this disease, accurate clinical staging, and the expected efficacy of each drug. The pharmacology of intravesical mytomycin C is discussed in detail, as many of this drug's pharmacological principles are applicable to all intravesical chemotherapeutic agents, including doxorubicin, thiotepa, bacillus Calmette-Guérin, epirubicin, and ethoglucid. The bladder wall, bladder cavity, chemical properties of intravesical chemotherapeutic agents, and tumor considerations are discussed. Suggestions based on pharmacological studies are presented to optimize the efficacy of intravesical chemotherapy.

Pharmacokinetics of intravesical doxorubicin in superficial bladder cancer patients

The urine and plasma pharmacokinetics of intravesical doxorubicin were studied in 8 patients with a history of superficial bladder cancer. Patients received 6 weekly treatments of 40 mg. doxorubicin in 20 ml. physiological saline. Doxorubicin was detectable (0.2 ng./ml. or more) in plasma from 6 of 8 patients during the initial treatment. The maximal concentrations ranged from 0.5 to 4.5 ng./ml. (mean 1.4). Doxorubicin was not detected in plasma from 7 of 8 patients during treatment 2 and not detected in any patient during treatment 4. The doxorubicin concentrations in urine decreased to approximately 50% at 5 minutes after dosing due to dilution by post-catheterization residual urine, and decreased by a further 6-fold by the end of the 2-hour treatment due to urine production. The recovery of doxorubicin at the end of treatment averaged 88.3%, with an additional recovery of 3.7% during the subsequent 4 hours. Urinary pH (range 5.5 to 8.5) did not affect the stability nor the systemic absorption of doxorubicin. In conclusion, we found that for intravesical doxorubicin therapy there was insignificant systemic exposure to doxorubicin, the highest systemic absorption from the bladder occurred shortly after surgery, there was high target site (bladder tissue) specificity, insignificant metabolism and/or degradation of doxorubicin, and dilution of urinary doxorubicin concentrations and, therefore, decreased tumor exposure to the drug due to residual urine and urine production.

The effects of intravesical chemoimmunotherapy with epirubicin and bacillus Calmette-Guérin for prophylaxis of recurrence of superficial bladder cancer: a preliminary report

The effects of intravesical chemoimmunotherapy with epirubicin and bacillus Calmette-Guérin (BCG) for prophylaxis of recurrence of superficial bladder cancer (pTa, pT1) were investigated in 29 patients aged a median of 70 years between January of 1991 and May of 1993. The patients received intravesical instillation of 40 mg epirubicin immediately after transurethral resection (TUR) of the bladder cancer. At 1 week after TUR, 80 mg Tokyo-strain BCG was instilled into the bladder once a week for 6 weeks. Thereafter, the patients were followed by cystoscopy and urinary cytology at 3-month intervals until recurrence was detected. Of the 29 patients, 28 had no evidence of disease over a mean follow-up period of 20 months. The 1 case of recurrence occurred at 3 months after TUR and that patient died of cancer progression. The simple recurrence rate was 3.5% after therapy. According to the person-years method, the number of recurrent tumors per 100 patient-months was 0.17. The cumulative nonrecurrence rate determined for all cases was 96.5% at 30 months. Adverse reactions, including urinary frequency, urgency, and miction pain, among others, were observed in 27 patients (93%). Only 1 patient was withdrawn from the treatment because of severe bladder-irritation symptoms due to the BCG instillation. The intravesical chemoimmunotherapy with epirubicin and BCG seemed to be effective for prophylaxis of recurrence of superficial bladder cancer.