A natively paired antibody library yields drug leads with higher sensitivity and specificity than a randomly paired antibody library.

Deep sequencing and single-chain variable fragment (scFv) yeast display methods are becoming more popular for discovery of therapeutic antibody candidates in mouse B cell repertoires. In this study, we compare a deep sequencing and scFv display method that retains native heavy and light chain pairing with a related method that randomly pairs heavy and light chain. We performed the studies in a humanized mouse, using interleukin 21 receptor (IL-21R) as a test immunogen. We identified 44 high-affinity binder scFv with the native pairing method and 100 high-affinity binder scFv with the random pairing method. 30% of the natively paired scFv binders were also discovered with the randomly paired method, and 13% of the randomly paired binders were also discovered with the natively paired method. Additionally, 33% of the scFv binders discovered only in the randomly paired library were initially present in the natively paired pre-sort library. Thus, a significant proportion of "randomly paired" scFv were actually natively paired. We synthesized and produced 46 of the candidates as full-length antibodies and subjected them to a panel of binding assays to characterize their therapeutic potential. 87% of the antibodies were verified as binding IL-21R by at least one assay. We found that antibodies with native light chains were more likely to bind IL-21R than antibodies with non-native light chains, suggesting a higher false positive rate for antibodies from the randomly paired library. Additionally, the randomly paired method failed to identify nearly half of the true natively paired binders, suggesting a higher false negative rate. We conclude that natively paired libraries have critical advantages in sensitivity and specificity for antibody discovery programs.

Quantification of 1-hydroxypyrene in undiluted human urine samples using magnetic solid-phase extraction coupled with internal extractive electrospray ionization mass spectrometry.

Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous environmental contaminants raising worldwide concerns due to their carcinogenic effects. In this study, 1-hydroxypyrene (1-OHP, the most widely used biomarker of internal dose of PAHs exposure) in undiluted human urine samples (10 mL) was selectively enriched by polypyrrole-coated Fe3O4 magnetite nanocomposites (termed as Fe3O4@Ppy, 1 mg) and then directly eluted by the electrospraying solvent (acetone/benzene/acetic acid (v/v/v, 90/10/1); 100 uL) biased with -3.5 kV to produce the deprotonated 1-OHP anions for mass spectrometric analysis. The method established here significantly improved the current performance for detection of urinary 1-OHP, providing the speed for a single sample analysis within 4 min, the limits of detection (LOD) of 0.0001 µg L(-1), the linear response range of 0.001-5.000 µg L(-1) (R(2) = 0.9994), recovery rates of 90.6-96.1%, and relative standard deviation (RSD, n = 6) values between 2.9% and 8.0%. Human samples including raw human urine collected from 10 healthy volunteers (5 smokers and 5 nonsmokers) and 7 lung cancer patients have been successfully analyzed, showing that magnetic solid-phase extraction (MSPE) coupled with internal extractive electrospray ionization mass spectrometry (iEESI-MS) is an alternative strategy for high throughput quantitative detection of urinary 1-OHP for health risk assessment of PAHs exposure.

In vitro characterization of the anti-PD-1 antibody nivolumab, BMS-936558, and in vivo toxicology in non-human primates.

The programmed death-1 (PD-1) receptor serves as an immunologic checkpoint, limiting bystander tissue damage and preventing the development of autoimmunity during inflammatory responses. PD-1 is expressed by activated T cells and downmodulates T-cell effector functions upon binding to its ligands, PD-L1 and PD-L2, on antigen-presenting cells. In patients with cancer, the expression of PD-1 on tumor-infiltrating lymphocytes and its interaction with the ligands on tumor and immune cells in the tumor microenvironment undermine antitumor immunity and support its rationale for PD-1 blockade in cancer immunotherapy. This report details the development and characterization of nivolumab, a fully human IgG4 (S228P) anti-PD-1 receptor-blocking monoclonal antibody. Nivolumab binds to PD-1 with high affinity and specificity, and effectively inhibits the interaction between PD-1 and its ligands. In vitro assays demonstrated the ability of nivolumab to potently enhance T-cell responses and cytokine production in the mixed lymphocyte reaction and superantigen or cytomegalovirus stimulation assays. No in vitro antibody-dependent cell-mediated or complement-dependent cytotoxicity was observed with the use of nivolumab and activated T cells as targets. Nivolumab treatment did not induce adverse immune-related events when given to cynomolgus macaques at high concentrations, independent of circulating anti-nivolumab antibodies where observed. These data provide a comprehensive preclinical characterization of nivolumab, for which antitumor activity and safety have been demonstrated in human clinical trials in various solid tumors.

A nonfucosylated human antibody to CD19 with potent B-cell depletive activity for therapy of B-cell malignancies.

A human anti-CD19 antibody was expressed in fucosyltransferase-deficient CHO cells to generate nonfucosylated MDX-1342. Binding of MDX-1342 to human CD19-expressing cells was similar to its fucosylated parental antibody. However, MDX-1342 exhibited increased affinity for FcγRIIIa-Phe158 and FcγRIIIa-Val158 receptors as well as enhanced effector cell function, as demonstrated by increased potency and efficacy in antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis assays. MDX-1342 showed dose-dependent improvement in survival using a murine B-cell lymphoma model in which Ramos cells were administered systemically. In addition, low nanomolar binding to cynomolgus monkey CD19 and increased affinity for cynomolgus monkey FcγRIIIa was observed. In vivo administration of MDX-1342 in cynomolgus monkeys revealed potent B-cell depletion, suggesting its potential utility as a B-lymphocyte depletive therapy for malignancies and autoimmune indications.

Characterization of new human CD20 monoclonal antibodies with potent cytolytic activity against non-Hodgkin lymphomas.

Despite the rapid and widespread integration of chimeric CD20 monoclonal antibody (mAb), rituximab, into the management of non-Hodgkin lymphoma, its efficacy remains variable and often modest when used as a single agent. To develop more potent reagents, human immunoglobulin transgenic mice were used to generate a panel of immunoglobulin G1kappa (IgG1kappa) CD20 mAbs. All reagents bound strongly to CD20(+) cells and recruited mononuclear cells for the lysis of malignant B cells. However, 2 mAbs, 2F2 and 7D8, were exceptionally active in complement-dependent cytotoxicity (CDC), being able to lyse a range of rituximab-resistant targets, such as CD20-low chronic lymphocytic leukemia (CLL), in the presence of human plasma or unfractionated blood. Further analysis showed that 2F2 and 7D8, like rituximab, redistributed CD20 into Triton X-100-insoluble regions of the plasma membrane, but that they had markedly slower off-rates. To determine whether off-rate influenced CDC, a non-complement activating F(ab')(2) antihuman kappa reagent was used. This reagent markedly slowed the off-rate of rituximab and increased its CDC activity to that of 2F2 and 7D8. Thus, with increasing evidence that mAb therapeutic activity in vivo depends on complement activation, these new CD20 reagents with their slow off-rates and increased potency in CDC hold considerable promise for improved clinical activity.