Pharmacological biocompatibility between intravesical preparations of BCG and interferon-alpha 2B

Bacillus Calmette-Guérin Retains Clinically Relevant Viability for up to 72 Hours After Reconstitution: Potential Implications for Clinical Practice in Times of Shortage

There have been repeated supply shortages of bacillus Calmette-Guérin (BCG), the gold-standard immunotherapy for patients with high-grade non-muscle-invasive bladder cancer (NMIBC). Organizations have issued guidance on coping with this shortage, including administering split-dose BCG such that one vial may treat up to three patients. However, logistical implementation of this strategy in a real-world setting is hampered by the recommendation to use BCG within 2 h of reconstitution. We assessed BCG viability in terms of colony-forming units (CFUs) and demonstrated that viability remained constant for at least 8 h after reconstitution (decline at 8 h of 9.1% for lot 1 [p =  0.3] and 4.8% for lot 2 [p =  0.2]). While the viability at 24 h was lower, it did not drop to a level below that of reducing the BCG dose to one-third (67% for lot 1 and 60% for lot 2) and remained close to 50% for at least 72 h. An in vitro model using co-culture of BCG and leukocytes with a BCG-sensitive cell line (RT4-V6) demonstrated no decrease in the cytotoxic potential of BCG at 72 h. In times of shortage, BCG vials may be split and administered for up to at least 8 h (or even 72 h) after reconstitution, allowing more patients to benefit from BCG while placing less strain on the logistics of clinical practice. PATIENT SUMMARY: The current supply of and increased demand for bacillus Calmette-Guérin (BCG), used in the treatment of bladder cancer, have led to repeated BCG shortages. One way to address this is to provide a reduced BCG dose to allow more patients to be treated. In this study we found that BCG viability remains clinically relevant up to 72 h after reconstitution, thus allowing for more patients to be treated from a single vial.

Interferon alfa in the treatment paradigm for non-muscle-invasive bladder cancer

OBJECTIVES

In this article, we review the various options for and the potential role of interferon alfa (IFN-α) in the treatment of non-muscle-invasive bladder cancer (NMIBC).

METHODS

PubMed was searched for journal articles on IFN-α use in treating bladder cancer. The references listed in the National Comprehensive Cancer Network guidelines were used as a guide to identify relevant publications on treatments for NMIBC.

RESULTS

Transurethral resection with adjuvant intravesical chemotherapy or immunotherapy is the standard treatment option for NMIBC. Adjuvant IFN-α therapy has limited efficacy in preventing recurrences in intermediate-risk and high-risk patients; bacillus Calmette-Guérin (BCG) monotherapy is the recommended first-line treatment in these patients. Unfortunately, cancer progression or recurrence is a common outcome; radical cystectomy, which is often the lifesaving approach in such a scenario, is associated with significant morbidity, mortality, and decreased quality of life. Current alternatives to cystectomy include repeat intravesical immunotherapy, conventional instillation chemotherapy, and device-assisted intravesical chemotherapy. The efficacy of any chemotherapy after BCG failure, either conventional or device assisted, has not been established. BCG and IFN-α combination intravesical therapy has not been investigated thoroughly; based on available data, combination therapy appears to be most effective in patients with carcinoma in situ and may be preferentially considered as an alternative to radical cystectomy for patients with intermediate-risk or high-risk NMIBC who do not tolerate the standard BCG dose or experience BCG failure after 1 year of therapy. However, this approach requires close follow-up and should only be chosen after careful consideration of all risk factors.

CONCLUSIONS

There is a lack of efficacious treatment options for patients with NMIBC recurrence or progression after initial BCG treatment. There is a need for well-designed clinical trials investigating the safety and efficacy of available therapies, including BCG and IFN-α2b combination therapy.

Potential of interferon-alpha in solid tumours: part 2

The second part of this review examines the use of recombinant interferon-alpha (rIFNalpha) in the following solid tumours: superficial bladder cancer, Kaposi's sarcoma, head and neck cancer, gastrointestinal cancers, lung cancer, mesothelioma and ovarian, breast and cervical malignancies. In superficial bladder cancer, intravesical rIFNalpha has a promising role as second-line therapy in patients resistant or intolerant to intravesical bacille Calmette-Guérin (BCG). In HIV-associated Kaposi's sarcoma, rIFNalpha is active as monotherapy and in combination with antiretroviral agents, especially in patients with CD4 counts >200/mm(3), no prior opportunistic infections and nonvisceral disease. rIFNalpha has shown encouraging results when used in combination with retinoids in the chemoprevention of head and neck squamous cell cancers. It is effective in the chemoprevention of hepatocellular cancer in hepatitis C-seropositive patients. In neuroendocrine tumours, including carcinoid tumour, low-dosage (</=3 MU) or intermediate-dosage (5 to 10 MU) rIFNalpha is indicated as second-line treatment, either with octreotide or alone in patients resistant to somatostatin analogues. Intracavitary IFNalpha may be useful in malignant pleural effusions from mesothelioma. Similarly, intraperitoneal IFNalpha may have a role in the treatment of minimal residual disease in ovarian cancer. In breast cancer, the only possible role for IFNalpha appears to be intralesional administration for resistant disease. IFNalpha may have a role as a radiosensitising agent for the treatment of cervical cancer; however, this requires confirmation in randomised trials. On the basis of current evidence, the routine use of rIFNalpha is not recommended in the therapy of head and neck squamous cell cancers, upper gastrointestinal tract, colorectal and lung cancers, or mesothelioma. Pegylated IFNalpha (peginterferon-alpha) is an exciting development that offers theoretical advantages of increased efficacy, reduced toxicity and improved compliance. Further data from randomised studies in solid tumours are needed where rIFNalpha has activity, such as neuroendocrine tumours, minimal residual disease in ovarian cancer, and cervical cancer. A better understanding of the biological mechanisms that determine response to rIFNalpha is needed. Studies of IFNalpha-stimulated gene expression, which are now feasible, should help to identify molecular predictors of response and allow us to target therapy more selectively to patients with solid tumours responsive to IFNalpha.

Second-generation interferons for cancer: clinical targets

IFNs were the first new therapeutic products resulting from recombinant DNA technology. IFNs were also the first human proteins effective in cancer treatment. There is however much to be discovered which will lead to new clinical applications. Areas which represent major research challenges for full understanding and application of the IFN system are: (i) the diversity of the IFN family; (ii) the role of induction; (iii) molecular mechanism of action; (iv) cellular modulatory effects; (v) advantages of combinations, and (vi) identification of new therapeutic indications. This review will emphasize the diversity of the IFN family and chemical modifications which will result in second-generation IFNs. Pre-clinical and clinical findings form the basis for new therapeutic directions in chronic myelogenous leukemia, lymphomas, myelomas, melanoma, urologic malignancies, primary brain tumors, and ovarian carcinoma.

Interferons and bladder cancer

With the introduction of BCG, intravesical instillation of immunotherapeutic agents has become a mainstay of therapy in the treatment of superficial bladder cancer. Interferon is capable of inducing a non-specific cellular and humoral immune response towards tumor cells. It has shown promise in reducing the recurrence and progression rates of superficial bladder cancer. In contrast to BCG, intravesical interferon is associated with minimal side effects and a very low dropout rate. Current research has focused on the use of interferon in combination with immunotherapeutic and cytotoxic drugs.

IFN-α 2B Enhances Th1 Cytokine Responses in Bladder Cancer Patients Receiving Mycobacterium bovis Bacillus Calmette-Guérin Immunotherapy

Combination therapy with intravesical bacillus Calmette-Guérin (BCG) plus IFN-α for superficial bladder cancer has been demonstrated to be more effective than either single agent alone in animal studies and of suggested greater efficacy in clinical studies. However, the mechanism by which IFN-α enhances BCG-mediated antitumor activity is poorly understood. Using PBMCs from bladder cancer patients, IFN-α was found to substantially enhance the efficacy of BCG to induce IFN-γ production. Among 34 patients tested, 80% showed &gt;4-fold increase. This effect of IFN-α was observed in both initial and memory responses to BCG. In addition, IFN-α up-regulated BCG-induced IL-12 and TNF-α and down-regulated BCG-induced IL-10. Neutralizing endogenous IL-10 or adding exogenous IL-12 provided further synergy for IFN-γ production. In clinical practice, intravesical IFN-α 2B (50 million units (MU)/dose) was observed to accelerate urinary IFN-γ production to low-dose BCG (one-tenth or one-third of a full dose) in patients treated with combination therapy compared with BCG alone. These results suggest that IFN-α is a potent BCG enhancer that polarizes the BCG-induced immune response toward the cellular immune pathway by promoting Th1 cytokine expression and reducing Th2 cytokine expression. This study provides an immunological basis for future rational use of IFN-α in conjunction with intravesical BCG for bladder cancer immunotherapy.

Superficial bladder cancer: the role of interferon-alpha

PURPOSE

We evaluate the clinical experience with recombinant interferon-alpha in superficial transitional cell carcinoma and discuss the most rational use of recombinant interferon-alpha in the context of current treatment options.

MATERIALS AND METHODS

The available data were reviewed and discussed at a consensus conference in August 1996. The conclusions and recommendations are those of the authors based on the consensus reached at that meeting.

RESULTS

While bacillus Calmette-Guerin (BCG) is recognized as the most efficacious intravesical agent in the prophylaxis and treatment of superficial transitional cell carcinoma, it is associated with significant toxicities and a 20 to 40% relapse rate. Interferons, particularly recombinant interferon-alpha, have demonstrated efficacy against primary and recurrent papillary transitional cell carcinoma and carcinoma in situ with minimal toxicity, although the response and relapse rates are inferior to BCG. Intravesical recombinant interferon-alpha therapy has also produced responses in patients who failed to respond or were refractory to BCG or chemotherapy.

CONCLUSIONS

The clinical experience suggests that recombinant interferon-alpha has an important role in the treatment of superficial transitional cell carcinoma, particularly as second line therapy following failure of BCG or chemotherapy, and it may have synergistic effects when combined with chemotherapy or BCG. We propose a prospective randomized study comparing the efficacy of recombinant interferon-alpha, BCG and BCG plus recombinant interferon-alpha as maintenance following complete response to primary BCG therapy. The proposed study would also investigate the efficacy of BCG plus recombinant interferon-alpha as second line therapy following BCG failure. This study will be important to determine the most effective strategy to integrate recombinant interferon-alpha into current treatment options for superficial bladder cancer.