IMMUNOTHERAPY OF BLADDER CANCER TARGETING P53

Immunotherapy for superficial bladder cancer

The treatment of superficial bladder cancer requires adjuvant therapies besides transurethral resection because of a high recurrence rate after this standard treatment alone. Current adjuvant therapies involve intravesical chemotherapy for patients at low and intermediate risk for recurrence and progression, and intravesical bacillus Calmette-Guérin for patients at intermediate and high risk. However, these adjuvant therapies fail in a significant number of patients, dictating the need for new and improved adjuvant treatment modalities for superficial bladder cancer. Immunotherapy aiming at the modulation of the immune system of the patient is a promising alternative adjuvant. This review discusses the current status of the clinical development of various immunotherapy approaches for superficial bladder cancer, including passive immunotherapy, immune stimulants, immunogene therapy and cancer vaccination.

Immunotherapy of urologic tumors: principles and progress

Immunotherapy is receiving interest as an alternative or adjuvant approach to the treatment of many malignancies. The potential for immune modulation as a treatment of solid tumors is the focus of cancer researchers throughout the world. Though not a novel idea, increasing technological sophistication and continued advancement in the understanding of the immune system have increased the number of novel therapeutic approaches. In urology, BCG is an excellent example of how modulation of the immune system can be used to treat malignancy, and we are only now beginning to understand its immune mechanisms. Numerous other immunotherapeutic approaches have been and are being developed and evaluated. We provide a brief overview of immunology and its relation to tumor development and growth, and focus on some of the immunotherapeutic approaches to renal cell carcinoma, prostate adenocarcinoma, and transitional cell carcinoma of the bladder.

Identification of p53 peptides recognized by CD8(+) T lymphocytes from patients with bladder cancer

In many types of cancer, p53 frequently accumulates in tumor cells and anti-p53 antibodies can be detected. However, only four CD8(+) T-cell epitopes from p53 have been identified in humans so far. To further analyze the development of a T-cell response against p53, peptides having binding motifs specific for HLA-A1, -A2, -A3, -A24, -B7, -B35, -B44, and -B51 molecules have been defined. The HLA-binding capacity of those peptides was tested, and the stability of formed complexes was defined. Thirteen peptides that bound to HLA-A24 and -B44 molecules are presented. The positive peptides were then used to detect the anti-p53 response of CD8(+) T lymphocytes from patients with bladder cancer. Six peptides, presented by HLA-A2, -B51, or -A24, were able to stimulate T cells from two patients (among 16) with tumor cells that strongly accumulated p53. On the contrary, p53 peptides systematically failed to stimulate T cells from healthy donors or patients with low or undetectable levels of p53 in their tumor cells. These results have led to the identification of four new potential T CD8(+) epitopes from p53: 194-203 associating with HLA-B51 and 204-212, 211-218, and 235-243 associating with HLA-A24.

Management of superficial bladder cancer: what is new?

The management of superficial bladder cancer has not changed much during the last years. Transurethral resections with adjuvant intravesical instillation to risk groups have been standard therapy. Cystoscopy and cytology have been used for follow-up. Recently combinations of drugs for instillation and new urinary markers for diagnosis and follow-up have been tested. The role of these new modalities has not been easily judged. Thus the timely advent of guidelines with policy recommendations will play an important part in improving the care of patients in the future.