Interaction of current cancer treatments and the immune system: implications for breast cancer therapeutics

Myeloid-derived suppressor cells are increased and correlated with type 2 immune responses, malnutrition, inflammation, and poor prognosis in patients with breast cancer

Myeloid-derived suppressor cells (MDSCs) have been identified in the majority of patients and experimental mice with tumors by their suppression of T cell activation. MDSCs have also been reported to be associated with chronic inflammation. In advanced cancer, the T helper (Th) cell balance tends to shift from Th1 to Th2 predominance, and immune function, including cell-mediated immunity, is impaired by cytokines produced by Th2 cells. The present study examined the correlations between MDSC levels and inflammation, immune suppression, malnutrition, and poor prognosis in 155 patients with breast cancer. The levels of MDSCs in preoperative patients and in patients with recurrent breast cancer were significantly higher compared with postoperative patients, patients with recurrent breast cancer who received chemotherapy and healthy volunteers. The MDSC levels of preoperative patients were significantly positively correlated with interleukin (IL)-6 production by peripheral blood mononuclear cells (PBMCs), the neutrophil/lymphocyte ratio and C-reactive protein, and were negatively correlated with the production of interferon-γ and IL-12, serum concentration of rapid turnover protein, and the stimulation index. These patients were divided into two groups based on the levels of MDSCs. In preoperative patients with MDSC levels >1.0% of total PBMCs, the overall survival of patients with stage IV disease was significantly shorter compared with other disease stages, and was also significantly shorter compared with patients with MDSC levels <1.0% of total PBMCs. Thus, the MDSC levels of preoperative patients may function as a good prognostic indicator, particularly in patients with advanced breast cancer.

In vivo manipulation of Vgamma9Vdelta2 T cells with zoledronate and low-dose interleukin-2 for immunotherapy of advanced breast cancer patients

The potent anti-tumour activities of gammadelta T cells have prompted the development of protocols in which gammadelta-agonists are administered to cancer patients. Encouraging results from small Phase I trials have fuelled efforts to characterize more clearly the application of this approach to unmet clinical needs such as metastatic carcinoma. To examine this approach in breast cancer, a Phase I trial was conducted in which zoledronate, a Vgamma9Vdelta2 T cell agonist, plus low-dose interleukin (IL)-2 were administered to 10 therapeutically terminal, advanced metastatic breast cancer patients. Treatment was well tolerated and promoted the effector maturation of Vgamma9Vdelta2 T cells in all patients. However, a statistically significant correlation of clinical outcome with peripheral Vgamma9Vdelta2 T cell numbers emerged, as seven patients who failed to sustain Vgamma9Vdelta2 T cells showed progressive clinical deterioration, while three patients who sustained robust peripheral Vgamma9Vdelta2 cell populations showed declining CA15-3 levels and displayed one instance of partial remission and two of stable disease, respectively. In the context of an earlier trial in prostate cancer, these data emphasize the strong linkage of Vgamma9Vdelta2 T cell status to reduced carcinoma progression, and suggest that zoledronate plus low-dose IL-2 offers a novel, safe and feasible approach to enhance this in a subset of treatment-refractory patients with advanced breast cancer.

Manipulation of indoleamine 2,3 dioxygenase; a novel therapeutic target for treatment of diseases

BACKGROUND

The discovery of indoleamine 2,3-dioxygenase (IDO) as a modulator for the maintenance of fetomaternal immuno-privileged state has been heralded as a significant step in further defining the role of IDO in immunobiology. IDO is an IFN-inducible, intracellular enzyme that catalyzes the initial and rate-limiting step in the degradation of the essential amino acid, tryptophan. It has been suggested that IDO has the capacity to regulate the immune system via two discrete mechanisms; firstly the deprivation of tryptophan, which is essential for T cell proliferation and via the cytotoxic effects of tryptophan metabolites on T(H)1 cell survival.

METHODS

The sources of information used to prepare the paper are published work on Pubmed/Medline. In this review, we examine the therapeutic role of modulating IDO activity a variety of disease states including tumour tolerance, chronic infection, transplant rejection, autoimmunity and asthma. We propose that IDO represents a novel therapeutic target for the treatment of these diseases. We also explore the diverse strategies which are being employed, either to augment or to inhibit IDO activity in order to modify various disease processes. The limitations associated with these strategies are also scrutinized.