Intravesical bacillus Calmette-Guérin therapy for T1 superficial bladder cancer

Bacillus Calmette-Guerin immunotherapy of bladder cancer induces selection of human leukocyte antigen class I-deficient tumor cells

Bacillus Calmette-Guerin (BCG) immunotherapy is a standard treatment for high-risk non-muscle-infiltrating bladder cancer patients. Although the outcomes are good, cancer relapse is observed in around 40% of patients. We present the comparative analysis of human leukocyte antigen (HLA) class I expression in recurrent bladder tumors in patients treated with mitomycin or BCG. HLA class I expression was analyzed by RT-Q-PCR and immunohistochemical techniques. Loss of heterozygosity (LOH) was determined by microsatellite amplification of markers in chromosome 6 and 15. More profound alterations in HLA class I expression were found in post-BCG recurrent tumors than in pre-BCG lesions, whereas mitomycin treatment did not change the HLA class I expression pattern. Post-BCG recurrent tumors also showed a higher incidence of structural defects underlying altered HLA class I expression. We hypothesize that the immunotherapy-activated immune system recognizes and eliminates tumor cells with reversible ("soft") HLA class I changes but not transformed cells with additional, irreversible ("hard") alterations. To our knowledge, this is the first clinical evidence of immunotherapy-induced immunoselection of HLA class I loss tumor variants in bladder cancer, although the study involved a small number of patients.

Regulation of leukocyte function by adenosine receptors

The immune system responds to cues in the microenvironment to make acute and chronic adaptations in response to inflammation and injury. Locally produced purine nucleotides and adenosine provide receptor-mediated signaling to all bone-marrow derived cells of the immune system to modulate their responses. This review summarizes recent advances in our understanding of the effects of adenosine signaling through G protein-coupled adenosine receptors on cells of the immune system. Adenosine A(2A) receptors (A(2A)Rs) have a generally suppressive effect on the activation of immune cells. Moreover, their transcription is strongly induced by signals that activate macrophages or dendritic cells through toll-like receptors, or T cells through T cell receptors. A(2A)R induction is responsible for producing a gradual dissipation of inflammatory responses. A(2A)R activation is particularly effective in limiting the activation of invariant NKT (iNKT) cells that play a central role in acute reperfusion injury. A(2A) agonists have clinical promise for the treatment of vaso-occlusive tissue injury. Blockade of A(2A) receptors may be useful to enhance immune-mediated killing of cancer cells. A(2B)R expression also is transcriptionally regulated by hypoxia, cytokines, and oxygen radicals. Acute A(2B)R activation attenuates the production of proinflammatory cytokines from macrophages, but sustained activation facilitates macrophage and dendritic cell remodeling and the production of acute phase proteins and angiogenic factors that may participate in evoking insulin resistance and tissue fibrosis. A(2B)R activation also influences macrophage and neutrophil function by influencing expression of the anti-inflammatory netrin receptor, UNC5B. The therapeutic significance of adenosine-mediated effects on the immune system is discussed.

Assessment of angiogenic factor, vascular endothelial growth factor, serum and urine level changes in superficial bladder tumor immunotherapy by intravesical Bacillus Calmette-Guerin

Background and Aim:

Bladder tumor is one of the most common genitourinary tumors. Management of non-muscle invasive (NMI) bladder tumors is primarily by transurethral resection (TURBT) followed by intravesical immunotherapy or chemotherapy. Bacillus Calmette-Guerin (BCG) is the most effective adjuvant therapy in NMI bladder tumor. Since angiogenesis is an essential factor in solid tumor progression and vascular endothelial growth factor (VEGF) is an important factor in angiogenesis, the aim of this study is the assessment of angiogenic factor, VEGF, serum and urine level changes in superficial bladder tumor immunotherapy by intravesical BCG.

Materials and Methods:

A total of 23 patients with bladder transitional cell carcinoma (TCC) in stage Ta/T1 or carcinoma insitu (CIS), low or high grade, which passed a 2-4 week period from TURBT participated in this study. Blood and urine samples were obtained at first and sixth sessions before instillation of BCG. Enzyme-linked immunosorbent assay (ELISA) method was used to obtain VEGF level in samples.

Results:

Urine and serum VEGF levels did not change significantly before and after BCG therapy. Changes in VEGF level were significantly different neither in low grade against high grade tumors nor in stage T1 against stage Ta tumors. A significant difference in VEGF level was seen between low grade and high grade tumors in serum after BCG therapy (P=0.007); but not in urine samples.

Conclusion:

Although intravesical BCG possesses anti-angiogenic activity, it seems that it exerts its effect through pathways other than VEGF, especially in low grade tumors.