PEP-TP56 enhances AAV transduction in a serotype-independent manner

Adeno-associated viruses (AAVs) have emerged as the most prominent gene therapy vectors. However, the need for high AAV doses to achieve clinical efficacy remains a key challenge to AAV utility in the clinic. High vector dose increases cost and has been majorly implicated in the activation of immune responses directed against the AAV capsid, as well as the therapeutic payload. In this study, we demonstrated the potency of a small peptide, PEP-TP56 (TP56), which effectively enhances transduction efficiency by an average of 2.5-fold in multiple cell lines of diverse origins. Additionally, TP56 outperforms other well characterized cell penetrating peptides (CPPs) like TAT, BIP2 and ARF which represents different classes of CPPs. We show similar enhancement of transduction in combination with multiple AAV serotypes, suggesting that the mechanism of action for TP56 is serotype independent. Mechanistically, TP56 increased AAV cellular uptake by two-fold in an heparan sulfate proteoglycan (HSPG)-dependent manner. Furthermore, genetic incorporation of TP56 in a transduction-incompetent HSPG-ablated AAV2 vector restores transduction to levels similar or higher than WT-AAV2 level, depending on the cell-type. In conclusion, we demonstrate that supplementing AAVs with TP56 robustly enhances AAV transduction which could potentially allow for the application of lower vector genomes in compartmentalized tissues.