CStone Pharmaceuticals announced the United States Food and Drug Administration (FDA) has recently granted approval to the company's Investigational New Drug (IND) application for the independently developed recombinant humanized anti-programmed death-1 (PD-1) monoclonal antibody (mAb) CS1003. This represents CStone's second drug candidate to receive IND approval from the FDA less than one month after US clinical trial approval for CS1001 (PD-L1), and demonstrates CStone's global clinical development capability.
"Since May this year, CS1003 has now quickly received clinical trial approvals in Australia, China, and the United States, indicating that there are high expectations behind the product itself," said Dr. Frank Jiang, Chairman and CEO of CStone. "I hope that in the future CS1003 can play a key role within combination cancer drug therapies."
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CS1003 is a full-length, humanized immunoglobulin G4 (IgG4) anti-PD-1 monoclonal antibody that has shown a good tolerability and efficacy profile in preclinical in vivo studies. The forthcoming clinical trial in the United States extends the Phase I study that began in Australia in May this year to US research centers, and will determine the recommended Phase II dose (RP2D) for CS1003 in solid tumor 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/PD-L1 pathway to successfully avoid immune system recognition. Targeting of the PD-1/PD-L1 checkpoint by anti-tumor drugs can block the "tumor immune evasion mechanism" and restore anti-cancer immune ability in patients.