We are a clinical-stage immunotherapy company developing a novel class of T cell engagers that harness the power of the body's immune system to treat patients suffering from cancer and other diseases. T cell engagers are engineered proteins that direct a patient's own T cells to kill target cells that express specific proteins, or antigens, carried by the target cells. Using our proprietary Tri-specific T cell Activating Construct, or TriTAC, platform, we are developing a pipeline of novel T cell engagers, or TriTACs, initially focused on the treatment of solid tumors and hematologic malignancies. Since commencing operations in 2015, we have created four TriTAC product candidates, each of which we expect to be in clinical development by the end of 2020. Our lead TriTAC product candidate, HPN424, is currently in a Phase 1 clinical trial for the treatment of metastatic castration-resistant prostate cancer, or mCRPC. In January 2019, we announced preliminary data from this trial that supports the proposed mechanism of action of HPN424. Our second TriTAC product candidate, HPN536, is expected to enter clinical development in the first half of 2019 for the treatment of ovarian cancer and other MSLN-expressing solid tumors.
In January 2019, we announced preliminary data from seven patients who had been enrolled in our Phase 1 clinical trial of HPN424, as of December 31, 2018. Safety and tolerability are the primary objectives of the trial and as of December 31, 2018, all seven patients remained on the study, receiving weekly treatments of HPN424 with no dose limiting toxicities. Our secondary objectives include pharmacokinetic and pharmacodynamic data, as well as preliminary anti-tumor activity. The clinical trial results to date include measurement of HPN424 serum exposure that supports weekly dosing and changes in cell and serum biomarkers consistent with T cell activation.
Our TriTACs are designed to advance the therapeutic potential of T cell engagers, an established and meaningful mechanism of action. The first bi-specific T cell engager, or BiTE, to be approved by the FDA was, Amgen's Blincyto. Blincyto was approved in 2014 as a monotherapy for the treatment of acute lymphoblastic leukemia. Since then, other BiTEs have shown promising therapeutic potential in clinical trials. We developed our proprietary TriTAC platform to incorporate the strengths of BiTEs and improve upon their critical shortcomings, such as a short half life. We believe our TriTAC platform offers the following features for the discovery and development of novel immunotherapies for the treatment of a wide array of diseases, including cancer: