After signing a licensing-in agreement, AptaTargets starts its R&D activity with a set of four candidates for Acute Stroke treatment. These aptamers have been identified in vitro and their efficacy has been validated through in vitro and in vivo studies with outstanding results.

ApTOLL consists of DNA aptamers, or single-stranded DNA molecules capable of acquiring a three-dimensional conformation specifically derived from their nucleotide sequence, with a high binding affinity, specificity and antagonistic activity on TLR4. ApTOLL arises as a novel therapy (for both the mechanism of action and the nature of the molecule) for the acute treatment of stroke by substantially reducing brain damage. ApTOLL is comprised by a molecule which has shown high efficacy as inhibitor of TLR4 activation in a sequential in vitro/in vivo selection process among millions of random nucleotide sequences.

ApTOLL acts as a TLR4 antagonist, blocking its activation by its ligands and, consequently, interfering with the initiation of the inflammatory response. ApTOLL could be administered in patients over a theoretical therapeutic window of up to 48 hours after the onset of stroke, either in stroke units or in emergency units (even mobile), in one or several doses as intravenous bolus or as slow infusion. The treatment would aim to reduce inflammation within the ischemic core and to prevent the expansion of inflammation to neighboring brain regions, thus reducing brain damage and functional affectation. ApTOLL could potentially be given in combination with other drugs with complementary mechanisms of action such as thrombolytics, but also individually in those patients that have exceeded the therapeutic window for thrombolysis.

Nuclei (blue) and aptamer (green)

Figure. Effects of ApTOLL administration after cerebral ischemia in mice. (A,B) Detection of aptamer in the proximity of the infarcted tissue (microscopy images). (A) Hematoxylin-eosin stained brain slice from MCAO mouse (2x). A disintegration of the tissue and a general loss of intensity of the cells were observed. (B) Fluorescence Microscopy. The ApTOLL is shown in the membrane of cells located adjacent to the infarct zone. Aptamers marked with Alexa488 y Hoechst (40X). (C) Efect of ApTOLL administration 10 min after ischemia. Quantification of TTC stained-brain slices in vehicle and ApTOLL-treated mice determined 24h after MCAO. A decrease on infarct volume is detected in ApTOLL-treated animals.