Science > The Cell Penetrating Peptide Initiative

Cell penetrating peptides (CPPs) are peptides of 8 to 30 residues in length that facilitate the uptake of drug cargoes into cells. Said cargoes may be small molecule drugs, other peptide sequences, proteins or nucleic acids that are associated with the CPP moiety via chemical linkage or electrostatic interactions. Interestingly, and whilst the majority of CPPs exhibit a very broad tropism in terms of the cell types that they are able to permeate, it has recently been shown that certain select sequences derived from venomous sources are capable of delivering drug cargoes into specific cell types both in vitro and in vivo.

Cell selective CPPs hold great promise as delivery vectors for use in medicine, as they allow one to selectively deliver drugs directly into specific cell types, thus assuring low dose efficacy whilst limiting exposure to other tissues and undesirable toxicity, two of the main reasons for the failure of drugs in clinical development. In addition, and if peptide-based drug cargos are used instead of small molecules, the technology further allows one to address previously “undruggable” intracellular targets, such as protein-protein interactions, and which is of enormous interest in the treatment of numerous diseases.

Accordingly, the Toxinomics Foundation has an ongoing research project focusing on the identification of novel CPPs which is being carried out in collaboration with two academic partners. In brief, candidate CPPs are identified by mining venomous sequence databases with proprietary algorithms, and are subsequently synthesized and tested for selectivity in various cell and tissue-based models. CPPs meeting the Foundation’s criteria for commercial tractability are subsequently appended to small molecule or peptide drug cargos, and tested in corresponding disease models.

To date, The Foundation has identified 28 families of novel CPP candidates which are currently being tested and expanded in tissue-selectivity assays, all of which are available for partnering. And through our highly productive collaborations with academia, we have also identified two additional CPPs: the first showing enhanced efficacy when appended to a widely used antineoplastic drug whose dosing regimens are limited by peripheral organ toxicity (and which is being progressed in hematological malignancies & brain tumors), and the second showing great promise as a vector for inducing the expression of CD4, CD8 and tumor epitopes in dendritic cells for use in cancer vaccines (and which is being progressed in prostate & colon cancer). Please visit our products page for further details.