Branka Petričević

Trastuzumab mediates antibody-dependent cell-mediated cytotoxicity and phagocytosis to the same extent in both adjuvant and metastatic HER2/neu breast cancer patients

BackgroundMonoclonal antibodies (mAb), such as trastuzumab are a valuable addition to breast cancer therapy. Data obtained from neoadjuvant settings revealed that antibody-dependent cell-mediated cytotoxicity (ADCC) is a major mechanism of action for the mAb trastuzumab. Conflicting results still call into question whether disease progression, prolonged treatment or concomitant chemotherapy influences ADCC and related immunological phenomena.MethodsWe analyzed the activity of ADCC and antibody-dependent cell-mediated phagocytosis (ADCP) of peripheral blood mononuclear cells (PBMCs) from human epidermal growth factor receptor 2 (HER2/neu) positive breast cancer patients receiving trastuzumab therapy either in an adjuvant (n = 13) or metastatic (n = 15) setting as well as from trastuzumab treatment-naive (t-naive) HER2/neu negative patients (n = 15). PBMCs from healthy volunteers (n = 24) were used as controls. ADCC and ADCP activity was correlated with the expression of antibody binding Fc-gamma receptor (FcγR)I (CD64), FcγRII (CD32) and FcγRIII (CD16) on CD14+ (monocytes) and CD56+ (NK) cells, as well as the expression of CD107a+ (LAMP-1) on CD56+ cells and the total amount of CD4+CD25+FOXP3+ (Treg) cells. In metastatic patients, markers were correlated with progression-free survival (PFS).ResultsADCC activity was significantly down regulated in metastatic, adjuvant and t-naive patient cohorts as compared to healthy controls. Reduced ADCC activity was inversely correlated with the expression of CD107a on CD56+ cells in adjuvant patients. ADCC and ADCP activity of the patient cohorts were similar, regardless of treatment duration or additional chemotherapy. PFS in metastatic patients inversely correlated with the number of peripheral Treg cells.ConclusionThe reduction of ADCC in patients as compared to healthy controls calls for adjuvant strategies, such as immune-enhancing agents, to improve the activity of trastuzumab. However, efficacy of trastuzumab-specific ADCC and ADCP appears not to be affected by treatment duration, disease progression or concomitant chemotherapy. This finding supports the application of trastuzumab at any stage of the disease.

Single-Nucleotide Polymorphisms in Genes Encoding Toll-Like Receptor -2, -3, -4, and -9 in Case–Control Study with Breast Cancer

BACKGROUND Genetic susceptibility to cancer is multifactorial, and it is known that impairment of the immune system could contribute to risk for getting cancer. AIM OF THE STUDY Single-nucleotide polymorphisms (SNPs) of Toll-like receptor (TLR) 2, TLR3, TLR4, and TLR9 genes, which are important for innate immunity, were analyzed for the association with breast cancer. METHODS The SNPs comprised TLR2 (c.597T>C), TLR2 (c.1350T>C), TLR3 (c.1377C>T), TLR4 (c.896A>G), and TLR9 (c.1635A>G). The allelic and genotypic frequencies of these TLR SNPs were compared between patients (n = 130) and controls (n = 101) in a case-control study from Croatia. RESULTS TLR SNPs were not significantly different. From the population genetics viewpoint, we found that a hypomorphic variant of TLR4 (p.Asp299Gly) allele has no specific allelic frequency (8.4%) in the Croatian population (n = 496) compared to other Caucasians (6.5-10%). CONCLUSION These results suggest that polymorphisms in tested TLR genes are not likely to be associated with increased risk for developing breast cancer.

Single Nucleotide Polymorphism in the Interleukin 12B Gene is Associated With Risk for Breast Cancer Development

We analysed the association of a single nucleotide polymorphism (SNP) in the gene encoding the IL‐12 subunit p40 (IL12B, rs3212227, A>C) with breast cancer. The SNPs allelic and genotypic frequencies were compared between patients (n = 191) and healthy (n = 194) women in a case–control study from Croatia. The major allele (A) was associated with susceptibility to breast cancer (P = 0.003; OR = 1.67; 95% CI: 1.17–2.38). Likewise, the minor allele (C) was significantly correlated with protection (P = 0.003; OR = 0.60; 95% CI: 0.42–0.86). At the genotype level, AA homozygosity was significantly associated with predisposition to disease (P = 0.013; OR = 1.68, 95% CI: 1.09–2.59), whereas the minor allele homozygosity (CC) was correlated with protection to disease (P = 0.020, OR = 0.28, 95% CI: 0.09–0.91). The heterozygous genotype showed no significant correlation with disease. The product of the IL12B gene (IL‐12 p40) can either form a homodimeric cytokine or be part of two pro‐inflammatory (IL‐12 and IL‐23) cytokines. It is presently unclear whether the major allele is associated with higher or lower protein levels of IL‐12 p40 and IL‐12 p70, which are critical in inflammation and adaptive immune responses. However, as the A allele is high producer of IL12B (p40) mRNA, these results might imply that higher levels of IL‐12 p40 (either as homodimers or joined with one or both of the other two subunits) predispose to breast cancer.

Cl097, a TLR7/8 ligand, inhibits TLR-4-dependent activation of IRAK-M and BCL-3 expression

Prolonged or repeated stimulation of Toll-like receptor (TLR) 4 leads to hyporesponsiveness of monocyte-derived macrophages, which seems to be a hallmark of immunosuppression related to sepsis and cancer. Two negative regulators of TLR-4 signaling are IL-1 receptor-associated kinase M and B-cell leukemia 3. Here, we demonstrate that the expression of both proteins is inhibited when the TLR-7/TLR-8 agonist CL097 is added to monocyte cultures despite costimulation with the TLR-4 agonist LPS or hyaluronic acid. Reduction of IL-1 receptor-associated kinase M and B-cell leukemia 3 was paralleled by a significant increased cytokine induction of TNF-&agr;, IL-10, and IL-12 observed after intracellular and extracellular TLR stimulation. In ex vivo stimulated whole blood of patients who have prolonged sepsis or metastatic cancer, TLR-7/TLR-8 agonists retained their ability of increased stimulation of TNF-&agr;. These data might add to the understanding of sepsis and cancer-associated immune suppression in men.

Heterozygous carriage of a dysfunctional Toll-like receptor 9 allele affects CpG oligonucleotide responses in B cells.

Background: Human B cells respond to Toll-like receptor (TLR) 9 stimulation by cytokine production. Results: A rare, novel TLR9 allele fails to activate NF-κB in HEK293 cells. Heterozygous carrier B cells show defective IL-6 and IL-10 production. Conclusion: Heterozygosity for this TLR9 allele modifies CpG oligonucleotide responsiveness. Significance: This is the first analysis of human TLR9 variants in primary cells. Toll-like receptors (TLR) are employed by the innate immune system to detect microbial pathogens based on conserved microbial pathogen molecules. For example, TLR9 is a receptor for CpG-containing microbial DNA, and its activation results in the production of cytokines and type I interferons from human B cells and plasmacytoid dendritic cells, respectively. Both are required for mounting an efficient antibacterial or antiviral immune response. These effects are mimicked by synthetic CpG oligodeoxynucleotides (ODN). Although several hyporesponsive TLR9 variants have been reported, their functional relevance in human primary cells has not been addressed. Here we report a novel TLR9 allele, R892W, which is hyporesponsive to CpG ODN and acts as a dominant-negative in a cellular model system. The R892W variant is characterized by increased MyD88 binding and defective co-localization with CpG ODN. Whereas primary plasmacytoid dendritic cells isolated from a heterozygous R892W carrier responded normally to CpG by interferon-α production, carrier B cells showed impaired IL-6 and IL-10 production. This suggests that heterozygous carriage of a hyporesponsive TLR9 allele is not associated with complete loss of TLR9 function but that TLR9 signals elicited in different cell types are regulated differently in human primary cells.