Monoclonal antibody ( mAb ) represents a class of therapeutics experienced dramatic development over the past 30 years. Because of the tremendous differences in physicochemical and biological properties between mAbs and small molecules, the mAb therapeutics significantly differ from the chemical drugs in pharmacokinetic characteristics and underlying mechanisms. Full understanding of those characteristics and mechanisms may efficiently guide the screening and development of mAb medi-cines, and would well support their safety evaluation and clinical dosage regimen designing. This review is to summarize pharma-cokinetics and underlying mechanisms of mAbs from the aspects of absorption, distribution and elimination, as well as the ap-proaches for prediction of mAb pharmacokinetics in humans.

Dysfunction in tyrosine kinase activity disrupts the nor-mal control of cellular phosphorylation signaling pathways,which plays a vital role in genesis and development of various tumors, and makes tyrosine kinases a class of targets of many anti-tumor drugs. Currently most approved tyrosine kinase inhibitors ( TKIs) are based on irreversible binding mechanisms, making them poorly selective, not potent or sustained enough regarding pharmacological effects and prone to triggering resistance. In the past decade, much progress has been made in the development of
a new class of TKIs which irreversibly inhibit their target proteins via the formation of covalent bonds, overcoming the drawbacks of irreversible TKIs. Several irreversible TKIs have entered markets or clinical research phases. This review is to summarize the structural, pharmacological and medicinal chemical properties of investigational and marketed irreversible TKIs as well as their re-cent developments.

Antibody-drug conjugate (ADC) is a new class of therapeutics composed of a monoclonal antibody and small cytotoxin moieties conjugated through a chemical linker. ADC molecules bind to the target antigens expressed on the tumor cell surfaces guided by the monoclonal antibody component. The binding ADC molecules can be internalized and subsequently the toxin moieties can be released within the tumor cells via chemical and/or enzymatic reactions to kill the target cells. The conjugation combines the merits of both components, i.e., the high target specificity of the monoclonal antibody and the highly potent cell killing activity of the cytotoxin moieties. However, such complexities make the pharmacokinetic and metabolic studies of ADCs highly challenging. The major challenges should include characterization of absorption, distribution, metabolism and excretion, investigation of underlying mechanisms, assessment of pharmacokinetic- pharmacodynamic relationship, and analytical method development of ADC drugs. This review will discuss common pharmacokinetic issues and considerations, as well as tools and strategies that can be utilized to characterize the pharmacokinetic and metabolic properties of ADCs.

Objective:To investigate the inhibitory effect of RMT1-10-induced tolerogenic dendritic cells (Tol-DCs) in vitro on high-risk corneal allograft rejection in mice and its mechanism. Methods:One hundred SPF male BALB/c mice and fifty SPF male C57BL/6 mice were selected.Bone marrow-derived immature dendritic cells (imDCs) obtained from C57BL/6 mice were divided into imDCs group, mature dentritic cells (mDCs) group, RMT1-10 group, and IgG isotype control group.The imDCs in the four groups were cultured with no intervention, lipopolysaccharide, RMT1-10 and lipopolysaccharide, or IgG isotype antibody and lipopolysaccharide for 7 days according to grouping.The expression levels of different phenotypes of DCs including CD11c, CD80, CD86, major histocompatibility complex (MHC)-Ⅱ, T cell immunoglobulin and mucin domain containing molecule (Tim)-4 and CD103 in the four groups were detected by flow cytometry.The concentrations of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) in the DCs supernatants were determined by enzyme-linked immunosorbent assay.A mixed lymphocyte culture system was established, and the stimulation index (SI) of CD4 + T cell proliferation stimulated with DCs was detected by cell counting kit 8 method.Corneal neovascularization was induced by corneal stromal suture in BALB/c mice, and the 80 mice with neovascularization in 4 quadrants growing into the middle and peripheral cornea were used as recipients.The recipient mice were randomized into imDCs group, mDCs group, RMT1-10 group, and IgG isotype control group using the random number table method, with 20 mice in each group.An injection of corresponding DCs (1×10 6 cells/100 μl) was administered to the recipient mice via the tail vein according to grouping.At 7 days following the injection, C57BL/6 mice were used as donors and penetrating keratoplasty was performed.Within one month after the operation, signs of corneal grafts rejection, including opacity, edema and neovascularization, were observed by slit lamp biomicroscopy and scored every day.At 21 days after the operation, 5 recipients selected from each group were subcutaneously injected with naive C57BL/6 splenocytes (1×10 6 cells/100 μl) behind the ear.The delayed type hypersensitivity (DTH) was evaluated by ear swelling at 24 hours after the subcutaneous injection.The use and care of experimental animals complied with the Regulations on the Management of Experimental Animals promulgated by the State Science and Technology Commission.This study protocol was approved by an Ethics Committee of the Affiliated Hospital of Chengde Medical University (No.CYFYLL2020055). Results:Compared with mDCs group, the expressions of CD80, CD86 and MHC-Ⅱ, and the percentage of Tim-4-positive cells in CD11c-positive cells were significantly decreased in RMT1-10 group, showing statistically significant differences (all at P<0.001). The percentage of Tim-4-positive cells were significantly decreased in RMT1-10 group than imDCs group, and the percentage of CD103-positive cells in RMT1-10 group was significantly higher than imDCs group, mDCs group and IgG isotype control group (all at P<0.001). The concentrations of IL-10 and TGF-β in the cell culture supernatant of RMT1-10 group were significantly higher than those of the other three groups, with statistically significant differences (all at P<0.001). There were statistically significant differences in the SI of CD4 + T cell proliferation simulated by DCs ( Fgroup=1 833.00, P<0.001; Fratio=230.40, P<0.001; Finteraction=3.06, P=0.01). The SI of DCs/CD4 + T cells ratio at 1∶5, 1∶10, 1∶20 and 1∶40 were all significantly lower in imDCs group than mDCs group, and were all significantly lower in RMT1-10 group than imDCs group (all at P<0.05). There was a statistically significant difference in corneal graft survival curve among various groups ( χ2=77.69, P<0.001). The survival rate of RMT1-10 group was significantly higher than that of imDCs group ( χ2=9.74, P=0.002), and the survival rate of imDCs group was significantly higher than that of mDCs group ( χ2=31.02, P<0.001). The ear swelling of recipient mice of positive control group, mDCs group, IgG isotype control group, imDCs group and RMT1-10 group was (503.6±17.2), (475.7±17.6), (456.2±18.8), (225.2±39.4), (118.1±12.6), and (106.4±7.4) μm, with a statistically significant difference among them ( F=377.10, P<0.001). The mice ear swelling was more serious in positive control group than mDCs group, more serious in IgG isotype control group than imDCs group, and more serious in imDCs group than RMT1-10 group (all at P<0.05). Conclusions:RMT1-10 can inhibit the rejection of high-risk corneal transplantation in mice, the mechanism of which may be attributed to inducing imDCs to transform into Tol-DCs in vitro and up-regulating the expression of TGF-β and IL-10, which promotes antigen-specific immune tolerance after adoptive transfer, thereby indirectly prolongs the survival of corneal grafts.

Objective: To examine the association between the frequencies of bowel movement (BMF) and the risk of colorectal cancer (CRC). Methods: In this study, 510 134 participants from the China Kadoorie Biobank (CKB) were included, after excluding those who reported as having been diagnosed with cancer at the baseline survey. The baseline survey was conducted from June 2004 to July 2008. The present study included data from baseline and follow-up until December 31, 2016. We used the Cox proportional hazards regression models to estimate the HR and the 95%CI of incident CRC with BMF. Results: During an average follow-up period of 9.9 years, 3 056 participants were documented as having developed colorectal cancer. In the site-specific analysis, 1 548 colon cancer and 1 475 rectal cancer were included. Compared with participants who had bowel movements on the daily base, the multivariable-adjusted HR (95%CI) for those who had more than once of BMF were 1.24 (1.12-1.39) for CRC, 1.12 (0.95-1.31) for colon cancer, and 1.37 (1.18-1.59) for rectal cancer. We further examined the association between BMF and CRC, according to the stages of follow-up, the corresponding HR (95%CI) for CRC, colon and rectal cancer were 1.59 (1.36-1.86), 1.43 (1.14- 1.80), and 1.76 (1.41-2.19) for the first five years, while such associations became statistically insignificant in the subsequent follow-up (P for all interactions were <0.05), as time went on. As for CRC, colon or rectal cancers among participants who had lower bowel movements, the risks were not significantly different from those who had bowel movements everyday. Conclusions Participants who had BMF more than once a day, appeared an increased risk of CRC in the subsequent five years. Since abnormal increase of bowel movements is easily recognizable, programs should be set up on health self- management and early screening for CRC.