CStone Pharmaceuticals has announced that a formal application for clinical trial approval has been submitted to Human Research Ethics Committees of the Scientia Clinical Research center in Australia for the anti-programmed death-1 (PD-1) monoclonal antibody (mAb) candidate CS1003. The application represents CStone's third novel independently-developed pipeline candidate to reach the clinical development stages, and the second such molecule to be filed for clinical trial approval in Australia.
CS1003 is a humanized IgG4 anti-PD-1 monoclonal antibody developed by CStone's proprietary hybridoma platform and has shown good tolerability and efficacy in in vivo studies. All global rights are retained by CStone. Upon receipt of the Ethics Committee's approval from the Scientia Clinical Research Center, CStone will initiate a phase I trial to assess the drug safety in patients with advanced cancers.
Dr. Jon Wang, senior vice-president, scientific Affairs of CStone commented: "In addition to high affinity and specificity for human PD-1, CS1003 also recognizes murine PD-1. This feature will significantly accelerate the preclinical research, broaden the ability to apply mouse tumor models to test combination approaches with multiple drug candidates in our pipeline, and lead to a faster assessment of combination strategies in the clinic to develop new therapies for cancer treatment."
The application for CS1003 coincides with a separate application from CStone to Linear Clinical Research in Australia for the independently developed mitogen-activated protein kinase kinase (MEK) small-molecule inhibitor CS3006. These two drug candidates are also actively being prepared to enter the clinical trial filing process in China.
Dr. Frank Jiang, chief executive officer (CEO) of CStone commented: "In just 18 months since CStone was established in April 2016, we not only successfully brought our anti-PD-L1 antibody CS1001 into clinical stage, but also are preparing to launch first-in-human trials in Australia for CS3006 and CS1003, which will further enrich our clinical stage portfolio. In addition to assessing single agent activity of these molecules, CStone will fully explore their potential in combination cancer therapies in order to provide new therapeutic options to patients."
PD-1, or programmed death-1, is an inhibitory checkpoint receptor expressed on T cells. Under normal circumstances, it binds with its ligands, programmed death ligand-1 or ligand 2 (PD-L1/PD-L2), inhibiting T cell and cytokine activation, serving to dampen the immune response in order to prevent damage to healthy tissues. However, studies have shown that PD-L1 can be abundantly expressed on the surface of many solid tumors as well as hematological malignancies. Cancer cells can therefore make use of the PD-1/L1 pathway in order to successfully avoid immune system recognition and attack. Targeting of the PD-1/PD-L1 checkpoint by anti-tumor drugs can blockade this "tumor immune evasion mechanism" and resume anti-cancer immune ability in patients.
Currently, there are two anti-PD-1 antibodies approved globally: Opdivo (nivolumab) from Bristol-Myers Squibb and Keytruda (pembrolizumab) from Merck, Sharp & Dohme. Comparing other anti-PD-1 mAbs, CS1003 can recognize both human and murine PD-1, providing an advantage during efficacy testing in syngeneic mouse tumor models. CS1003 has demonstrated good tolerability and efficacy in in vivo studies.