Nanobody-Fc constructs targeting chemokine receptor CXCR4 potently inhibit signaling and CXCR4-mediated HIV-entry and induce antibody effector functions.

Upregulation of the chemokine receptor CXCR4 contributes to the progression and metastasis of both solid and hematological malignancies, rendering this receptor an attractive therapeutic target. Besides the only FDA-approved CXCR4 antagonist Plerixafor (AMD3100), multiple other classes of CXCR4-targeting molecules are under (pre-)clinical development. Nanobodies (Nb), small single variable domains of heavy-chain only antibodies from Camelids, have appeared to be ideal antibody-fragments for targeting a broad range of epitopes and cavities within GPCRs such as CXCR4. Compared to conventional antibodies, monovalent nanobodies show fast blood clearance and no effector functions. In order to further increase their binding affinities and to restore antibody-mediated effector functions, we have constructed three different bivalent nanobody Fc-fusion molecules (Nb-Fc), targeting distinct epitopes on CXCR4, via fusion of Nbs to a Fc domain of a human IgG1 antibody. Most Nb-Fc constructs show increased binding affinity and enhanced potency in CXCL12 displacement, inhibition of CXCL12-induced signaling and CXCR4-mediated HIV entry, when compared to their monovalent Nb counterparts. Moreover, Nb-Fc induced ADCC- and CDC-mediated cell-death of CXCR4-overexpressing CCRF-CEM leukemia cells and did not affect cells expressing low levels or no CXCR4. These highly potent CXCR4 Nb-Fc constructs with Fc-mediated effector functions are attractive molecules to therapeutically target CXCR4-overexpressing tumors.

Pharmacokinetics of radiolabeled dimeric sdAbs constructs targeting human CD20.

Single-domain antibody fragments (sdAbs) are the smallest functional antigen-binding fragments, derived from heavy chain-only camelid antibodies. When designed as radiolabeled monomeric probes for imaging and therapy of cancer, their fast and specific targeting results in high tumor-to-background ratios early after injection. However, their moderate absolute uptake into tumors might not always be sufficient to treat cancerous lesions. We have evaluated the pharmacokinetics of seven constructs derived from a CD20-targeting monomeric sdAb (αCD20). The constructs differed in affinity or avidity towards CD20 (dimeric αCD20-αCD20 and αCD20 fused to a non-targeting control sdAb, referred to as αCD20-ctrl) and blood half-lives (αCD20 fused to an albumin-targeting sdAb (αAlb) = αCD20-αAlb). The constructs were radiolabeled with 111In (imaging) and 177Lu (therapy) using the bifunctional chelator CHX-A"-DTPA and evaluated in vitro and in vivo. In mice, tumor uptake of 177Lu-DTPA-αCD20 decreased from 4.82 ±â€¯1.80 to 0.13 ±â€¯0.05% IA/g over 72 h. Due to its rapid blood clearance, tumor-to-blood (T/B) ratios of >100 were obtained within 24 h. Although in vitro internalization indicated that dimeric 177Lu-DTPA-αCD20-αCD20 was superior in terms of total cell-associated radioactivity, this was not confirmed in vivo. Blood clearance was slower and absolute tumor uptake became significantly higher for αCD20-αAlb. Blood levels of 177Lu-DTPA-αCD20-αAlb decreased from 68.30 ±â€¯10.53 to 3.58 ±â€¯0.66% IA/g over 120 h, while tumor uptake increased from 6.21 ±â€¯0.94 to 24.90 ±â€¯2.83% IA/g, resulting in lower T/B ratios. Taken together, these results indicate that the increased size of dimeric αCD20-αCD20 or the fusion of monomeric αCD20 to an albumin-targeting moiety (αAlb) counterbalance their improved tumor targeting capacity compared to monomeric αCD20.

Adipokines and genetic factors in overweight or obese but metabolically healthy Polish women.

OBJECTIVE: Obesity may be accompanied by enhanced metabolic disturbances but not all obese patients suffer from metabolic syndrome. Since metabolic homeostasis is under control of genetic factors underlying expression of adipokines, we aimed to compare the serum concentrations of adiponectin and resistin, and polymorphism in their genes, in overweight or obese Polish women. MATERIAL AND METHODS: The study included 265 women with BMI above 25 kg/m2 (140 metabolically healthy and 125 with metabolic syndrome) and 104 non-obese women as a control group. Anthropometric parameters (BMI, BIA, WHR), blood pressure, lipid, glucose and HOMA-IR profiles as well as serum concentrations of adiponectin, HMW adiponectin and resistin were evaluated. Gene polymorphisms of adiponectin gene (276G/T; 11377C/G; 11391G/A) and resistin gene (420C/G; 62G/A; 537A/C) were analyzed using TaqMan SNP genotyping assays. RESULTS: Higher serum concentrations of total adiponectin and lower levels of resistin were found in metabolically healthy patients when compared to those diagnosed with metabolic syndrome. No differences of serum HMW and resistin concentrations were observed between overweight or obese but metabolically healthy subjects and normal weight controls. No associations of investigated polymorphisms and the presence of metabolic syndrome were noticed in overweight/obese women with metabolic syndrome. CONCLUSIONS: The assessment of total adiponectin in sera seems to be promising target in distinguishing subjects with obesity who undergo a diagnostic procedure for metabolic syndrome. Moreover, the evaluation of adipokine array may help to select patients with higher risk of metabolic disturbances that are associated with severe diseases.