Enzyme-linked immunosorbent assays for quantification of MMAE-conjugated ADCs and total antibodies in cynomolgus monkey sera

Antibody-drug conjugates(ADCs)are commonly heterogeneous and require extensive assessment of exposure-efficacy and exposure-safety relationships in preclinical and clinical studies.In this study,we report the generation of a monoclonal antibody against monomethyl auristatin E(MMAE)and the development,validation,and application of sensitive and high-throughput enzyme-linked immunosorbent assays(ELISA)to measure the concentrations of MMAE-conjugated ADCs and total antibodies(tAb,antibodies in ADC plus unconjugated antibodies)in cynomolgus monkey sera.These assays were successfully applied to in vitro plasma stability and pharmacokinetic(PK)studies of SMADC001,an MMAE-conjugated ADC against trophoblast cell surface antigen 2(TROP-2).The plasma stability of SMADC001 was better than that of similar ADCs coupled with PEG4-Val-Cit,Lys(m-dPEG24)-Cit,and Val-Cit linkers.The developed ELISA methods for the calibration standards of ADC and tAb revealed a correlation between serum concentrations and the OD450 values,with R2 at 1.000,and the dynamic range was 0.3-35.0 ng/mL and 0.2-22.0 ng/mL,respectively;the intra-and inter-assay accuracy bias%ranged from -12.2% to -5.2%,precision ranged from -12.4% to -1.4%,and the relative standard deviation(RSD)was less than 6.6% and 8.7%,respectively.The total error was less than 20.4%.The development and validation steps of these two assays met the acceptance criteria for all addressed validation parameters,which suggested that these can be applied to quantify MMAE-conjugated ADCs,as well as in PK studies.Furthermore,these assays can be easily adopted for development of other similar immunoassays.

基于摩擦伏特效应的超滑表征技术

Friction occurs in our daily lives, and statistics have shown that it consumes approximately 1/3 of the primary energy. In addition,mechanical interface friction significantly impacts the efficiency,noise, accuracy, corrosion, reliability, and operational lifespans of equipment. Several studies have revealed various methods for reducing the coefficient of friction (COF) to the superlubricity state(COF <0.01) through efficient lubrication technology.

Preventive and therapeutic benefits of nelfinavir in rhesus macaques and human beings infected with SARS-CoV-2

Effective drugs with broad spectrum safety profile to all people are highly expected to combat COVID-19 caused by SARS-CoV-2.Here we report that nelfinavir,an FDA approved drug for the treatment of HIV infection,is effective against SARS-CoV-2 and COVID-19.Preincubation of nelfinavir could inhibit the activity of the main protease of the SARS-CoV-2(IC50=8.26μM),while its antiviral activity in Vero E6 cells against a clinical isolate of SARS-CoV-2 was determined to be 2.93μM(EC50).In comparison with vehicle-treated animals,rhesus macaque prophylactically treated with nelfinavir had significantly lower temperature and significantly reduced virus loads in the nasal and anal swabs of the animals.At necropsy,nelfinavir-treated animals had a significant reduction of the viral replication in the lungs by nearly three orders of magnitude.A prospective clinic study with 37 enrolled treatment-naive patients at Shanghai Public Health Clinical Center,which were randomized(1:1)to nelfinavir and control groups,showed that the nelfinavir treatment could shorten the duration of viral shedding by 5.5 days(9.0 vs.14.5 days,P=0.055)and the duration of fever time by 3.8 days(2.8 vs.6.6 days,P=0.014)in mild/moderate COVID-19 patients.The antiviral efficiency and clinical benefits in rhesus macaque model and in COVID-19 patients,together with its well-established good safety profile in almost all ages and during pregnancy,indicated that nelfinavir is a highly promising medication with the potential of preventative effect for the treatment of COVID-19.

SARS-CoV-2 Omicron RBD shows weaker binding affinity than the currently dominant Delta variant to human ACE2

Dear Editor,SARS-coronavirus-2(SARS-CoV-2)Omicron variant(B.1.1.529)is of great concern to the world due to its multiple mutations that may have an impact on transmissibility and immune evasion.1 Compared to the wild type(WT),Omicron carries as many as 30 single point mutations,3 deletion mutation and one insertion mutation on its spike protein.Strikingly,there are 15 mutations observed in the Omicron receptor-binding domain(RBD),10 of which are in the receptor-binding motif(RBM)that human angiotensin-converting enzyme 2(ACE2)and most monoclonal antibodies(mAbs)interact directly with.As a comparison,the currently dominant variant Delta(B.1.617.2)has only 2 mutations(L452R and T478K)in its RBM and additional K417N and E484K mutations sometimes.Therefore,Omicron variant may significantly impact the binding affinity to ACE2 and effectiveness of currently available mAbs.Consequently,Omicron mutant has aroused wide concern,many countries have taken measures on entry restrictions to prevent its rapid spread.However,the transmissibility and immune evasion risk of Omicron have not been properly evaluated.

One-step synthesis of site-specific antibody-drug conjugates by reprograming IgG glycoengineering with LacNAc-based substrates

Glycosite-specific antibody-drug conjugatess(gsADCs), harnessing Asn297 N-glycan of IgG Fc as the conjugation site for drug payloads, usually require multi-step glycoengineering with two or more enzymes, which limits the substrate diversification and complicates the preparation process.Herein, we report a series of novel disaccharide-based substrates, which reprogram the IgG glycoengineering to one-step synthesis of gsADCs, catalyzed by an endo-N-acetylglucosaminidase(ENGase) of Endo-S2. IgG glycoengineering via ENGases usually has two steps: deglycosylation by wild-type(WT) ENGases and transglycosylation by mutated ENGases. But in the current method, we have found that disaccharide LacNAc oxazoline can be efficiently assembled onto IgG by WT Endo-S2 without hydrolysis of the product, which enables the one-step glycoengineering directly from native antibodies.Further studies on substrate specificity revealed that this approach has excellent tolerance on various modification of 6-Gal motif of LacNAc. Within 1 h, one-step synthesis of gsADC was achieved using the LacNAc-toxin substrates including structures free of bioorthogonal groups. These gsADCs demonstrated good homogeneity, buffer stability, in vitro and in vivo anti-tumor activity. This work presents a novel strategy using LacNAc-based substrates to reprogram the multi-step IgG glycoengineering to a one-step manner for highly efficient synthesis of gsADCs.