Biological response modifiers for the treatment of superficial bladder tumors.
BACKGROUND
For more than 20 years, superficial bladder tumors have been demonstrated to be sensitive to several biological response modifiers and especially to immunomodulators. The best-known and studied immunomodulator is the bacillus Calmette-Guérin (BCG). However, despite its well-recognized efficacy, BCG is not a universal panacea and is associated with potentially significant side effects.


METHODS
New perspectives in BCG therapy aiming to increase BCG efficacy or to decrease side effects include the use of genetically engineered BCG strains producing cytokines as well as the use of purified BCG subcomponents. Because a cascade of immunological reactions including the secretion of several cytokines has been demonstrated in the BCG mode of action, many other biological response modifiers and especially immunomodulators have been studied for superficial transitional cell carcinoma therapy. Some were investigated in human trials, others are still in laboratory studies; some are administered intravesically whereas others are given orally. Interferon-alpha (IFN-alpha) intravesical instillations have been evaluated in several controlled studies.


RESULTS
Although toxicity of intravesical IFN is minimal, its optimal dose, schedule and efficacy remain to be defined. Recent prospective studies comparing IFN to BCG intravesical therapy have been somewhat disappointing although this cytokine may be effective in some patients with T(a)-T(1) disease who have failed BCG therapy. Other immunomodulators administered intravesically investigated in clinical studies include interleukin 2 (recently used in a clinical study with a marker tumor response), levamisole, Rubratin, a Nocardia rubra cell wall skeleton, and keyhole limpet hemocyanin. Several biological response modifiers administered orally such as vitamin A (and its derivatives), Lactobacillus casei or bropirimine have been tested in clinical trials as well. In contrast, Allium sativum (garlic) or OK-432 (a streptococcal preparation) or BCG subfractions have been tested in laboratory studies only.


CONCLUSIONS
Published reports on several of these biological response modifiers suggest that these compounds may be an alternative in patients with superficial bladder cancer who have failed or have not tolerated BCG, but further evaluation to improve efficacy, durability and understand their mechanism of action is warranted.
Zlotta
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AR
Department of Urology, Erasme Hospital, University Clinics of Brussels, Belgium. azloota@ulb.ac.be
Schulman
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CC
D000283:Administration, Intravesical; D000284:Administration, Oral; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use*; D007978:Levamisole / Q000627:therapeutic use; D009367:Neoplasm Staging; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000473:pathology
D007155:Immunologic Factors; D007978:Levamisole