Non-Lung Solid Organ Transplantation From SARS-CoV-2-Positive Donors to Uninfected Recipients.

BACKGROUND: There is a paucity of evidence on the risk of donor-recipient transmission of the SARS-CoV-2 in solid organ transplant recipients. Initial impressions suggest non-lung solid organs may be safely transplanted from SARS-CoV-2-positive donors without risk of viral transmission. METHODS: We reviewed clinical results of transplants in which SARS-CoV-2-negative recipients received non-lung solid organs from SARS-CoV-2-positive donors at a single transplant center. No prisoners were used in this study, and participants were neither coerced nor paid. The manuscript was created in compliance with the Helsinki Congress and the Declaration of Istanbul. RESULTS: Between June 2021 and January 2023, we transplanted 26 solid organs, including 13 kidneys, 8 livers, 3 hearts, and 1 simultaneous heart and kidney, from 23 SARS-CoV-2-positive donors into 25 SARS-CoV-2 negative recipients. Two of the recipients had a positive SARS-CoV-2 real-time polymerase chain reaction after transplantation, but otherwise, patients had no SARS-CoV-2-related complications, and all patients to date are alive with excellent allograft function. CONCLUSION: Transplantation of non-lung solid organs from SARS-CoV-2-positive donors into uninfected recipients can be safely performed without adverse effects from SARS-CoV-2.

Outcomes in Post-operative Delirium Following Bowel Resection: A Single Center Retrospective Review.

INTRODUCTION: Delirium is associated with adverse post-operative outcomes, long-term cognitive dysfunction, and prolonged hospitalization. Risk factors for its development include longer surgical duration, increased operative complexity and invasiveness, and medical comorbidities. This study aims to further evaluate the incidence of delirium and its impact on outcomes among patients undergoing both elective and emergency bowel resections. METHODS: This is a retrospective cohort study using an institutional patient registry. All patients undergoing bowel resection over a 3.5-year period were included. The study measured the incidence of post-operative delirium via the nursing confusion assessment method. This incidence was then compared to patient age, emergency versus elective admission, length of stay, mortality, discharge disposition, and hospital cost. RESULTS: A total of 1934 patients were included with an overall delirium incidence of 8.8%. Compared to patients without delirium, patients with delirium were more likely to have undergone emergency surgery, be greater than 70 y of age, have a longer length of stay, be discharged to a skilled nursing facility, and have a more expensive hospitalization. In addition, the overall mortality was 14% in patients experiencing delirium versus 0.1% in those that did not. Importantly, when broken down between elective and emergency groups, the mortality of those experiencing delirium was similar (11 versus 13%). CONCLUSIONS: The development of delirium following bowel resection is an important risk factor for worsened outcomes and mortality. Although the incidence of delirium is higher in the emergency surgery population, the development of delirium in the elective population infers a similar risk of mortality.

Patching of the Inferior Vena Cava Following Lateral Venorrhaphy in Penetrating Traumatic Injury.

Penetrating injury to the inferior vena cava (IVC) is associated with high morbidity and mortality. Luminal narrowing can occur following lateral venorrhaphy and can lead to future morbidity. This case report discusses the success of patch repair following lateral venorrhaphy in two trauma patients. We describe the use of patch repair to eliminate stenosis of the IVC resulting from primary repair in the setting of traumatic injury. Furthermore, trauma patients are known to be at high risk for venous thromboembolism, and we describe the use of low molecular weight heparin as chemical prophylaxis for prevention of this complication following patch repair.

Discovery and optimization of a novel anti-GUCY2c x CD3 bispecific antibody for the treatment of solid tumors.

We report here the discovery and optimization of a novel T cell retargeting anti-GUCY2C x anti-CD3ε bispecific antibody for the treatment of solid tumors. Using a combination of hybridoma, phage display and rational design protein engineering, we have developed a fully humanized and manufacturable CD3 bispecific antibody that demonstrates favorable pharmacokinetic properties and potent in vivo efficacy. Anti-GUCY2C and anti-CD3ε antibodies derived from mouse hybridomas were first humanized into well-behaved human variable region frameworks with full retention of binding and T-cell mediated cytotoxic activity. To address potential manufacturability concerns, multiple approaches were taken in parallel to optimize and de-risk the two antibody variable regions. These approaches included structure-guided rational mutagenesis and phage display-based optimization, focusing on improving stability, reducing polyreactivity and self-association potential, removing chemical liabilities and proteolytic cleavage sites, and de-risking immunogenicity. Employing rapid library construction methods as well as automated phage display and high-throughput protein production workflows enabled efficient generation of an optimized bispecific antibody with desirable manufacturability properties, high stability, and low nonspecific binding. Proteolytic cleavage and deamidation in complementarity-determining regions were also successfully addressed. Collectively, these improvements translated to a molecule with potent single-agent in vivo efficacy in a tumor cell line adoptive transfer model and a cynomolgus monkey pharmacokinetic profile (half-life>4.5 days) suitable for clinical development. Clinical evaluation of PF-07062119 is ongoing.

In vitro affinity optimization of an anti-BDNF monoclonal antibody translates to improved potency in targeting chronic pain states in vivo.

The role of brain-derived neurotrophic factor (BDNF) signaling in chronic pain has been well documented. Given the important central role of BDNF in long term plasticity and memory, we sought to engineer a high affinity, peripherally-restricted monoclonal antibody against BDNF to modulate pain. BDNF shares 100% sequence homology across human and rodents; thus, we selected chickens as an alternative immune host for initial antibody generation. Here, we describe the affinity optimization of complementarity-determining region-grafted, chicken-derived R3bH01, an anti-BDNF antibody specifically blocking the TrkB receptor interaction. Antibody optimization led to the identification of B30, which has a > 300-fold improvement in affinity based on BIAcore, an 800-fold improvement in potency in a cell-based pERK assay and demonstrates exquisite selectivity over related neurotrophins. Affinity improvements measured in vitro translated to in vivo pharmacological activity, with B30 demonstrating a 30-fold improvement in potency over parental R3bH01 in a peripheral nerve injury model. We further demonstrate that peripheral BDNF plays a role in maintaining the plasticity of sensory neurons following nerve damage, with B30 reversing neuron hyperexcitability associated with heat and mechanical stimuli in a dose-dependent fashion. In summary, our data demonstrate that effective sequestration of BDNF via a high affinity neutralizing antibody has potential utility in modulating the pathophysiological mechanisms that drive chronic pain states.

Establishing in vitro in vivo correlations to screen monoclonal antibodies for physicochemical properties related to favorable human pharmacokinetics.

Implementation of in vitro assays that correlate with in vivo human pharmacokinetics (PK) would provide desirable preclinical tools for the early selection of therapeutic monoclonal antibody (mAb) candidates with minimal non-target-related PK risk. Use of these tools minimizes the likelihood that mAbs with unfavorable PK would be advanced into costly preclinical and clinical development. In total, 42 mAbs varying in isotype and soluble versus membrane targets were tested in in vitro and in vivo studies. MAb physicochemical properties were assessed by measuring non-specific interactions (DNA- and insulin-binding ELISA), self-association (affinity-capture self-interaction nanoparticle spectroscopy) and binding to matrix-immobilized human FcRn (surface plasmon resonance and column chromatography). The range of scores obtained from each in vitro assay trended well with in vivo clearance (CL) using both human FcRn transgenic (Tg32) mouse allometrically projected human CL and observed human CL, where mAbs with high in vitro scores resulted in rapid CL in vivo. Establishing a threshold value for mAb CL in human of 0.32 mL/hr/kg enabled refinement of thresholds for each in vitro assay parameter, and using a combinatorial triage approach enabled the successful differentiation of mAbs at high risk for rapid CL (unfavorable PK) from those with low risk (favorable PK), which allowed mAbs requiring further characterization to be identified. Correlating in vitro parameters with in vivo human CL resulted in a set of in vitro tools for use in early testing that would enable selection of mAbs with the greatest likelihood of success in the clinic, allowing costly late-stage failures related to an inadequate exposure profile, toxicity or lack of efficacy to be avoided.

Augmented Binary Substitution: Single-pass CDR germ-lining and stabilization of therapeutic antibodies.

Although humanized antibodies have been highly successful in the clinic, all current humanization techniques have potential limitations, such as: reliance on rodent hosts, immunogenicity due to high non-germ-line amino acid content, v-domain destabilization, expression and formulation issues. This study presents a technology that generates stable, soluble, ultrahumanized antibodies via single-step complementarity-determining region (CDR) germ-lining. For three antibodies from three separate key immune host species, binary substitution CDR cassettes were inserted into preferred human frameworks to form libraries in which only the parental or human germ-line destination residue was encoded at each position. The CDR-H3 in each case was also augmented with 1 ± 1 random substitution per clone. Each library was then screened for clones with restored antigen binding capacity. Lead ultrahumanized clones demonstrated high stability, with affinity and specificity equivalent to, or better than, the parental IgG. Critically, this was mainly achieved on germ-line frameworks by simultaneously subtracting up to 19 redundant non-germ-line residues in the CDRs. This process significantly lowered non-germ-line sequence content, minimized immunogenicity risk in the final molecules and provided a heat map for the essential non-germ-line CDR residue content of each antibody. The ABS technology therefore fully optimizes the clinical potential of antibodies from rodents and alternative immune hosts, rendering them indistinguishable from fully human in a simple, single-pass process.

Comprehensive interrogation of a minimalist synthetic CDR-H3 library and its ability to generate antibodies with therapeutic potential.

We have generated large libraries of single-chain Fv antibody fragments (>10(10) transformants) containing unbiased amino acid diversity that is restricted to the central combining site of the stable, well-expressed DP47 and DPK22 germline V-genes. Library WySH2A was constructed to examine the potential for synthetic complementarity-determining region (CDR)-H3 diversity to act as the lone source of binding specificity. Library WySH2B was constructed to assess the necessity for diversification in both the H3 and L3. Both libraries provided diverse, specific antibodies, yielding a total of 243 unique hits against 7 different targets, but WySH2B produced fewer hits than WySH2A when selected in parallel. WySH2A also consistently produced hits of similar quality to WySH2B, demonstrating that the diversification of the CDR-L3 reduces library fitness. Despite the absence of deliberate bias in the library design, CDR length was strongly associated with the number of hits produced, leading to a functional loop length distribution profile that mimics the biases observed in the natural repertoire. A similar trend was also observed for the CDR-L3. After target selections, several key amino acids were enriched in the CDR-H3 (e.g., small and aromatic residues) while others were reduced (e.g., strongly charged residues) in a manner that was specific to position, preferentially occurred in CDR-H3 stem positions, and tended towards residues associated with loop stabilization. As proof of principle for the WySH2 libraries to produce viable lead candidate antibodies, 114 unique hits were produced against Delta-like ligand 4 (DLL4). Leads exhibited nanomolar binding affinities, highly specific staining of DLL4+ cells, and biochemical neutralization of DLL4-NOTCH1 interaction.

Affinity maturation of a humanized rat antibody for anti-RAGE therapy: comprehensive mutagenesis reveals a high level of mutational plasticity both inside and outside the complementarity-determining regions.

Antibodies that neutralize RAGE (receptor for advanced glycation end products)-ligand interactions have potential therapeutic applications in both acute and chronic diseases. We generated XT-M4, a rat anti-RAGE monoclonal antibody that has in vivo efficacy in an acute sepsis model. This antibody was subsequently humanized. To improve the affinity of this antibody for the treatment of chronic indications, we used random and targeted mutagenesis strategies in combination with ribosome and phage-display technologies, respectively, to generate libraries of XT-M4 variants. We identified a panel of single-chain Fv antibody fragments (scFv's) that was improved up to 110-fold in a homogeneous time-resolved fluorescence competition assay against parental XT-M4 immunoglobulin G (IgG). After reformatting to bivalent scFv-Fc fusions and IgGs, we observed similar gains in potency in the same assay. Further analysis of binding kinetics as IgG revealed multiple variants with subnanomolar apparent affinity that was dictated primarily by improvements in the off-rate. All variants also had improved binding to cell surface-expressed human RAGE, and all retained, or had improved, apparent affinity for mouse RAGE. F100bL in V(H) (variable region of the heavy chain) complementarity-determining region 3 (CDR3) was one of a number of key mutations that correlated with affinity improvements and was independently identified by both mutagenesis strategies. Random mutagenesis coupled with ribosome display and high-throughput screening revealed an unexpectedly high level of mutational plasticity across the whole length of the humanized scFv, suggesting greater scope for structural optimization outside of the primary antigen-combining site defined by V(H) CDR3 and V(kappa) CDR3. In summary, our comprehensive mutagenesis approach not only achieved the desired affinity maturation of XT-M4 but also defined multiple mutational hotspots across the antibody sequence, provided an insight into the specificity-determining residues of the antibody paratope, and identified additional sites within the CDR loops where human germ-line amino acids may be introduced without affecting function.