Ex vivo evaluation of adhesive strength and barrier effect of a novel treatment for esophagitis.

AIM: To investigate the mucoadhesive strength and barrier effect of Esophacare® (Atika Pharma SL, Las Palmas de Gran Canaria) in an ex vivo model of gastro-oesophageal reflux. METHODS: An ex vivo evaluation through the Falling Liquide Film Technique with porcine esophagi was performed, compared to a positive control (Ziverel®; Norgine, Amsterdam), after different washing periods with saline, acidified saline (pH 1.2) and acidified saline with pepsin (2000U/mL). RESULTS: The adhesive mean strength on the oesophageal mucosa of Esophacare was 94.7 (6.0)%, compared to 27.6 (19.1)% of the positive control (p<0.05). These results were homogeneous across the different washes and throughout the tissue. The area covered by 1mL of Esophacare, and its respective persistence after washing was also assessed, yielding a mean global persistence of 74.29 (19.7)% vs. 18.9 (12.3)% for the control (p<0.05). In addition, after 30min exposure to acidified saline with pepsin, Esophacare shows a protective effect on the oesophageal mucosa, detectable histologically: preserved integrity and structure of the apical layers was observed, as well as reduced permeability to the washing solution. CONCLUSIONS: Esophacare shows an adhesive strength close to 100%, irrespective of the washing solution applied or the oesophageal region studied. Histologically, it reduces the abrasive effects of the acidic solution on the oesophageal epithelium, reducing permeability to the washing solution. The results in this ex vivo model of gastro-oesophageal reflux disease (GERD) support its therapeutic potential.

Nanobody-Based EGFR-Targeting Immunotoxins for Colorectal Cancer Treatment.

Immunotoxins (ITXs) are chimeric molecules that combine the specificity of a targeting domain, usually derived from an antibody, and the cytotoxic potency of a toxin, leading to the selective death of tumor cells. However, several issues must be addressed and optimized in order to use ITXs as therapeutic tools, such as the selection of a suitable tumor-associated antigen (TAA), high tumor penetration and retention, low kidney elimination, or low immunogenicity of foreign proteins. To this end, we produced and characterized several ITX designs, using a nanobody against EGFR (VHH 7D12) as the targeting domain. First, we generated a nanoITX, combining VHH 7D12 and the fungal ribotoxin α-sarcin (αS) as the toxic moiety (VHHEGFRαS). Then, we incorporated a trimerization domain (TIEXVIII) into the construct, obtaining a trimeric nanoITX (TriVHHEGFRαS). Finally, we designed and characterized a bispecific ITX, combining the VHH 7D12 and the scFv against GPA33 as targeting domains, and a deimmunized (DI) variant of α-sarcin (BsITXαSDI). The results confirm the therapeutic potential of α-sarcin-based nanoITXs. The incorporation of nanobodies as target domains improves their therapeutic use due to their lower molecular size and binding features. The enhanced avidity and toxic load in the trimeric nanoITX and the combination of two different target domains in the bispecific nanoITX allow for increased antitumor effectiveness.