Engineered TFPI-2 KD1 Peptide Therapeutics for Control of Excessive Bleeding (UCLA Case Nos. 2019-981, 2012-611, 2006-064)

UCLA researchers in the School of Medicine have developed engineered peptide therapeutics based on the tissue factor pathway inhibitor-2 (TFPI-2) Kunitz domain 1 (KD1), which can serve as potent inhibitors of fibrinolysis to control excessive bleeding.

BACKGROUND: Excessive bleeding remains a major unmet need in hematology, surgery, trauma care, and other settings in which fibrin clots are broken down too quickly. Fibrinolysis, the physiological degradation of fibrin clots, is primarily driven by plasmin. Uncontrolled plasmin activity can cause hyperfibrinolysis and clinically significant blood loss during cardiac bypass surgery, trauma, thrombolytic therapy, organ transplantation, and orthopedic surgery. Existing antifibrinolytic agents lack high affinity and specificity, necessitating high doses which can lead to side effects and organ toxicity. The use of aprotinin, a potent plasmin inhibitor, has been limited by safety concerns associated with off-target protease inhibition of kallikrein. Therefore, there is a strong need for more potent, selective, and well-tolerated antifibrinolytic agents to stabilize clots and reduce blood loss.

INNOVATION: UCLA researchers led by Dr. Paul Bajaj have engineered related mutant peptides from human TFPI-2 KD1, a naturally derived plasmin inhibitor. They have conducted biochemical and clotting studies to show that selected variants improve plasmin inhibition and clot strength relative to wild type KD1. Furthermore, in vivo studies in mice indicate that these engineered peptides reduce blood loss and outperform wild type KD1 and current antifibrinolytic. Notably, these engineered peptides are strong inhibitors of plasmin while showing minimal inhibition of kallikrein, a potentially important selectivity advantage.  In vivo studies also showed no renal toxicity or immune reactions in response to these peptides. Thus, this technology can serve as a targeted hematology therapeutic for safe and effective management of excessive bleeding.

POTENTIAL APPLICATIONS:

• Prevention and treatment of excessive bleeding associated with surgery
• Management of hyperfibrinolysis
• Trauma/hemorrhage control
• Clot stabilization in high risk procedures (e.g. transplantation)

ADVANTAGES:

• Potent antifibrinolytic activity and reduced blood loss
• High plasmin selectivity with minimal kallikrein inhibition
• No renal toxicity or detectable immune response

DEVELOPMENT-TO-DATE: The engineered peptides have been validated by biochemical, clotting, and in vivo mouse studies.

Related Papers (from the inventors only):

• Bajaj MS, Ogueli GI, Kumar Y, Vadivel K, Lawson G, Shanker S, Schmidt AE, Bajaj SP. Engineering kunitz domain 1 (KD1) of human tissue factor pathway inhibitor-2 to selectively inhibit fibrinolysis: properties of KD1-L17R variant. J Biol Chem. 2011 Feb 11;286(6):4329-40. doi: 10.1074/jbc.M110.191163. Epub 2010 Nov 29. PMID: 21115497; PMCID: PMC3039392.
• Kumar Y, Vadivel K, Schmidt AE, Ogueli GI, Ponnuraj SM, Rannulu N, Loo JA, Bajaj MS, Bajaj SP. Decoy plasminogen receptor containing a selective Kunitz-inhibitory domain. Biochemistry. 2014 Jan 28;53(3):505-17. doi: 10.1021/bi401584b. Epub 2014 Jan 13. PMID: 24383758; PMCID: PMC3985851.
• Vadivel K, Kumar Y, Ogueli GI, Ponnuraj SM, Wongkongkathep P, Loo JA, Bajaj MS, Bajaj SP. S2'-subsite variations between human and mouse enzymes (plasmin, factor XIa, kallikrein) elucidate inhibition differences by tissue factor pathway inhibitor -2 domain1-wild-type, Leu17Arg-mutant and aprotinin. J Thromb Haemost. 2016 Dec;14(12):2509-2523. doi: 10.1111/jth.13538. Epub 2016 Nov 19. PMID: 27797450; PMCID: PMC5504414.
• Vadivel, K., Zaiss, A. K., Kumar, Y., Fabian, F. M., Ismail, A. E. A., Arbing, M. A., Buchholz, W. G., Velander, W. H., & Bajaj, S. P. (2020). Enhanced Antifibrinolytic Efficacy of a Plasmin-Specific Kunitz-Inhibitor (60-Residue Y11T/L17R with C-Terminal IEK) of Human Tissue Factor Pathway Inhibitor Type-2 Domain1. Journal of Clinical Medicine, 9(11), 3684. https://doi.org/10.3390/jcm9113684

Keywords: Tissue factor pathway inhibitor-2, TFPI-2, Kunitz domain 1, KD1, mutant polypeptide, plasmin inhibitor, protease inhibitor, antifibrinolytic, fibrin clot, blood loss, thrombolytic therapy, organ transplantation, orthopedic surgery, anti-cancer, hemorrhage, hyperfibrinolysis, engineered peptide, trauma