The stability and aggregation of NIST monoclonal antibody (NISTmAb) were investigated by hydrogen/deuterium exchange mass spectrometry (HDX-MS), differential scanning calorimetry (DSC), and nano-differential scanning fluorimetry (nanoDSF). NISTmAb was prepared in eight formulations at four different pHs (pH 5, 6, 7, and 8) in the presence and absence of 150 mM NaCl and analyzed by the three methods. The HDX-MS results showed that NISTmAb is more conformationally stable at a pH near its isoelectric point (pI) in the presence of NaCl than a pH far from its pI in the absence of NaCl. The stabilization effects were global and not localized. The midpoint temperature of protein thermal unfolding transition results also showed the C H 2 domain of the protein is more conformationally stable at a pH near its pI. On the other hand, the onset of aggregation temperature results showed that NISTmAb is less prone to aggregate at a pH far from its pI, particularly in the absence of NaCl. These seemingly contradicting results, higher conformational stability yet higher aggregation propensity near the pI than far away from the pI, can be explained by intramolecular and intermolecular electrostatic repulsion using Lumry-Eyring model, which separates folding/unfolding equilibrium and aggregation event. The further a pH from the pI, the higher the net charge of the protein. The higher net charge leads to greater intramolecular and intermolecular electrostatic repulsions. The greater intramolecular electrostatic repulsion destabilizes the protein and the greater intermolecular electrostatic repulsion prevents aggregation of the protein molecules at pH far from the pI.
Mucosal immunity is dominated by secretory IgA and IgM, although these are less favorable compared to IgG molecules for therapeutic development. Polymeric IgA and IgM are actively transported across the epithelial barrier via engagement of the polymeric Ig receptor (pIgR), but IgG molecules lack a lumen-targeted active transport mechanism, resulting in poor biodistribution of IgG therapeutics in mucosal tissues. In this work, we describe the discovery and characterization of single-domain antibodies (VHH) that engage pIgR and undergo transepithelial transport across the mucosal epithelium. The anti-pIgR VHH panel displayed a broad range of biophysical characteristics, epitope diversity, IgA competition profiles and transcytosis activity in cell and human primary lung tissue models. Making use of this diverse VHH panel, we studied the relationship between biophysical and functional properties of anti-pIgR binders targeting different domains and epitopes of pIgR. These VHH molecules will serve as excellent tools for studying pIgR-mediated transport of biologics and for delivering multispecific IgG antibodies into mucosal lumen, where they can target and neutralize mucosal antigens.
Accelerated timelines necessitate the discovery of fully human antibodies as biotherapeutics using transgenic animals with a notion that such mAbs bypass humanization. A transgenic animal derived mAb (PCa75) targeted against a prostate cancer antigen had several 'unusual residues' (rare somatic hypermutations, rSHM, with positional frequency of <1%) that resulted in compromised biophysical properties (tm = 61 °C and intrinsic stability ΔGu = 24.3 kJ/mol) and a sub-optimal immunogenicity profile. In our quest for quality medicine, we pursued antibody engineering strategies to enhance the stability of PCa75. PCa62, an engineered variant of PCa75, retained function while significantly improving the drug-like attributes of the molecule (Tm = 75 °C and intrinsic stability ΔGu = 63.5 kJ/ mol). rSHM is rather prevalent, 18 out the 21 approved transgenic animal-derived antibodies have at least one 'unusual residue'. Thus, engineering of rSHM remains critical to enhance the stability and minimize immunogenicity risk of biotherapeutics. Monoclonal antibodies (mAbs) have fundamentally transformed the treatment of complex diseases like autoimmune disorders, cancer, and others over the last two decades 1. The complex physicochemical makeup of these biologics compared to traditional small molecule drugs is manifested in development challenges associated with immunogenicity, aggregation, chemical stability, and physical stability during drug production and delivery. These challenges are outweighed by the unmatched specificity, potency, and safety of these molecules such that mAbs remain a growing source of therapeutic molecules, particularly in Oncology applications, with over 100 new mAbs entering clinical trials yearly 2. With over 570 mAbs currently being tested in clinical trials with overlapping targets, mechanisms, and disease indications, optimization of a drug's physical attributes can result in a significant competitive advantage while also providing better value to patients. Humanized antibodies represent ~43% (i.e. 38 mAbs) of the 89 FDA approved antibodies 2. Although once tedious and time consuming, synthetic biology breakthroughs, sequencing technologies, and worldwide services for high-throughput antibody engineering have drastically reduced the time required for humanization. More recently several transgenic animal platforms have been developed to discover fully human therapeutic antibodies in rodents, circumventing the iterative process of humanization 3,4. Indeed, 21 biotherapeutics derived from four different transgenic animal platforms such as UltimAb, Xenomouse, VelocImmune and TransChromo platforms have been approved and marketed while antibodies from other transgenic animals' platforms like Merus, Harbour Biomed, Ablexis, Wuxi Pharma, Open Monoclonal Technology among others are currently in clinical trials 5. Recreating the human immune system in transgenic animals is challenging as antibody genes are assembled by V-D-J recombination and further diversified by somatic hyper-mutations to enhance specificit...
<div><p>The success of chimeric antigen receptor (CAR) T-cell therapy against hematologic malignancies has altered the treatment paradigm for patients with these diseases. Nevertheless, the occurrence of relapse due to antigen escape or heterogeneous antigen expression on tumors remains a challenge for first-generation CAR T-cell therapies as only a single tumor antigen can be targeted. To address this limitation and to add a further level of tunability and control to CAR T-cell therapies, adapter or universal CAR T-cell approaches use a soluble mediator to bridge CAR T cells with tumor cells. Adapter CARs allow simultaneous or sequential targeting of multiple tumor antigens, control of immune synapse geometry, dose control, and the potential for improved safety. Herein, we described a novel CAR T-cell adapter platform that relies on a bispecific antibody (BsAb) targeting both a tumor antigen and the GGGGS (G<sub>4</sub>S) linker commonly used in single-chain Fv (ScFv) domains expressed on CAR T-cell surfaces. We demonstrated that the BsAb can bridge CAR T cells to tumor cells and potentiate CAR T-cell activation, proliferation, and tumor cell cytolysis. The cytolytic activity of CAR T-cells was redirected to different tumor antigens by changing the BsAb in a dose-dependent manner. This study highlights the potential of G<sub>4</sub>S-displaying CAR T cells to be redirected to engage alternative tumor-associated antigens (TAA).</p>Significance:<p>New approaches are needed to address relapsed/refractory disease and manage potential toxicities associated with CAR T-cell therapy. We describe an adapter CAR approach to redirect CAR T cells to engage novel TAA-expressing cells via a BsAb targeting a linker present on many clinical CAR T-cell therapeutics. We anticipate the use of such adapters could increase CAR T-cell efficacy and reduce potential CAR-associated toxicities.</p></div>
TMEFF2, a transmembrane protein with epidermal growth factor-like and 2 follistatin-like domains, is primarily restricted in expression to healthy brain and prostate and is enriched in prostate cancer. JNJ-70218902 (JNJ-902) is a bispecific antibody that engages TMEFF2-expressing tumor cells and CD3 on T cells causing exposure dependent pro-inflammatory responses and target tumor cell lysis. Here we report the preclinical characterization of JNJ-902 using in vitro and in vivo prostate cancer models. Expression of TMEFF2 transcript and protein in brain and prostate was confirmed in healthy human tissue, as was its elevated expression in advanced prostate cancer tumors, including in 41/45 (91%) metastatic castration-resistant prostate cancer (mCRPC) samples. JNJ-902 bound to TMEFF2-positive LNCaP-AR cells (androgen-sensitive human prostate cancer cell line) in a concentration-dependent manner (EC50 = 9.6 nM); no binding to TMEFF2-negative DU145 prostate cancer cells was observed. The binding affinity (KD) of JNJ-902 for CD3 on primary human T cells was determined to be ~151 nM. T cell-mediated killing, as measured by caspase-3 activity, was induced upon incubation of JNJ-902 with healthy human donor T cells (n = 5) and LNCaP-AR cells at a 3:1 effector to target ratio (EC50 = 1.4 nM). No cytotoxicity was detected using DU145 cells or with control antibodies. Corresponding T cell activation was confirmed by concentration-dependent increases in cell surface CD8+CD25+ expression and proinflammatory cytokine production (eg, GM-CSF, IFN-γ, IL-10, TNF-α). Antitumor activity of JNJ-902 at increasing concentrations up to 5 mg/kg was observed in T cell humanized NSG mice bearing LNCaP xenografts (tumor growth inhibition [∆%TGI] of 75-122%) and in LuCaP 86.2 patient-derived xenografts (∆%TGI of 72-88%) as compared with control-treated mice. JNJ-902-dependent intratumoral infiltration of CD8+ T cells was detected in both models with increases in frequency of CD8+granzymeB+ effector cells. The data summarized here are the first report on the pharmacological activity of a novel TMEFF2 × CD3 bispecific antibody, supporting further investigation of TMEFF2 in mCRPC given its expression in advanced prostate cancer. Targeting TMEFF2 with the TMEFF2 × CD3 bispecific antibody JNJ-902 elicited robust T cell-mediated responses in both prostate cancer cells and xenograft models. Based on these data, a phase 1 dose escalation trial of JNJ-902 in patients with mCRPC is currently ongoing (NCT04397276). Citation Format: Subhasree Basu, Mike Russell, Katrin Sproesser, Bethany Mattson, Cassandra L. Lowenstein, Sathya Venkataramani, Maura Diamond, Robin E. Ernst, Stephen Jarantown, Jackson Wong, Gerald Chu, Kathryn Packman, Shaozhou Ken Tian, Scott R. Brodeur, Margaret Yu, Brent A. Rupnow. Characterization of JNJ-70218902, a TMEFF2 x CD3 bispecific antibody, in prostate cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB087.
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