CS1003, a novel human and mouse cross-reactive PD-1 monoclonal antibody for cancer therapy.

The programmed cell death protein 1 (PD-1) is an immune-checkpoint that negatively regulates the immune system and a key mechanism that tumors utilize to escape from immune surveillance. PD-1 antibodies can block the interaction of PD-1 with its ligands (PD-L1 and PD-L2), restore T cells activation, and elicit antitumor activity. In this paper, we reported a novel PD-1 monoclonal antibody (mAb) CS1003, which is a humanized IgG4 PD-1 mAb generated by conventional hybridoma technology, and currently being developed in multiple clinical trials as monotherapy or in combination with other anticancer agents. We showed that CS1003 bound to recombinant human, cynomolgus monkey, and mouse PD-1 with EC50 values of 0.1757, 0.2459, and 0.3664 nM, respectively. CS1003 blocked PD-1 interaction with its ligands, dose-dependently enhanced T cell proliferation and secretion of cytokines (IL-2 and IFN-γ) to the levels comparable to the reference antibody pembrolizumab. Intraperitoneal administration of CS1003 (0.1, 0.5, 2.5 mg/kg, once every 3 days) dose-dependently suppressed the growth of MC38-hPD-L1 colon cancer in hPD-1 knock-in mice. Pharmacokinetics (PK) study revealed a linear PK profile within the dose range of 2-18 mg/kg following single intravenous administration in cynomolgus monkey. These data provide a comprehensive preclinical characterization of CS1003 that supports its clinical development for cancer immunotherapy.

[A high content screening method for detection of anaphylactoid reaction of injection formulations].

Anaphylactoid reaction (AR) is the most common adverse reaction of injection formulations, however, there are obvious drawbacks in available methods for AR detection. A novel in vitro detection method for AR was established based on fluorescent labeling and high content screen (HCS) system in present study. With the use of RBL-2H3 cells degranulation model, positive cell count was determined with specific cellular membrane fluorescent dye FM4-64 labeling vesicle recycle, and total cells count was determined with specific nucleus fluorescent dye Hochest 3334, and then the ratio of cells degranulation after drug stimulation was calculated. In order to verify the reliability of this HCS method, positive drug Compound 48/80 was first used to confirm the consistence of HCS method with the traditional ß-hexosaminidase release test and the Evans blue staining ears test in mice. The results showed high consistence between HCS method and traditional testing methods, and the HCS method showed higher sensitivity than the other two tests. Then 30 samples of Danhong injection (DHI) with clinical allergy symptoms further were used to confirm the reliability of this HCS method. The HCS results showed high consistence with the clinical report, and the HCS method had the advantage in reducing the interference by drug color. Therefore, this HCS method is reliable, sensitive, simple and high-throughput method in detection of AR, applicable for the AR evaluation of injection formulations, and can provide guidance for safety of clinical application in clinical practice.

IL-12p40 is not required for islet allograft rejection.

AIM: To investigate whether IL-12p40 plays a crucial role in regulating islet allograft rejection in a streptozotocin (STZ)-induced diabetes mouse model. METHODS: C57BL/6 and IL-12p40 gene knockout mice were selected as recipient mice, to which the diabetes was induced with a treatment of STZ (150-200 mg/kg) by a single ip injection. BALB/c mice were selected as donor mice and islet cells were isolated from the mice. The 500 islets were transplanted into recipient mice beneath the capsule of the left kidney. Following the islet transplantation the glucose from the mice sera was monitored and the rejection rate of islets was analyzed. RESULTS: STZ could induce diabetes in the recipient mice within 1 week. After transplantation of allograft islets, the increased glucose in wild-type (WT) mice returned to normal level and was maintained for 10 d. Unexpectedly, the rejection rate of islet allograft between IL-12p40-deficient mice and WT mice was similar. CONCLUSION: The results suggested that, although islet allograft rejection is believed to be Th1-cell predominant, the Th1 response inducer, IL-12 and IL-23 are not essential to induce islet allograft rejection.