Search

PEGylation is routinely used to extend the systemic circulation of various protein therapeutics and nanomedicines. Nonetheless, mounting evidence is emerging that individuals exposed to select PEGylated therapeutics can develop antibodies specific to PEG, i.e., anti-PEG antibodies (APA). In turn, APA increase both the risk of hypersensitivity to the drug as well as potential loss of efficacy due to accelerated blood clearance of the drug. Despite the broad implications of APA, the timescales and systemic specificity by which APA can alter the pharmacokinetics and biodistribution of PEGylated drugs remain not well understood. Here, we developed a physiologically based pharmacokinetic (PBPK) model designed to resolve APA’s impact on both early- and late-phase pharmacokinetics and biodistribution of intravenously administered PEGylated drugs. Our model accurately recapitulates PK and biodistribution data obtained from PET/CT imaging of radiolabeled PEG-liposomes and PEG-uricase in mice with and without APA, as well as serum levels of PEG-uricase in humans. Our work provides another illustration of the power of high-resolution PBPK models for understanding the pharmacokinetic impacts of anti-drug antibodies and the dynamics with which antibodies can mediate clearance of foreign species.

Pegloticase is an enzyme used to reduce serum uric acid levels in patients with chronic, treatment-refractory gout. Clinically, about 40% of patients develop high titers of anti-PEG antibodies (APA) after initial treatment, which in turn quickly eliminate subsequent doses of pegloticase from the systemic circulation and render the treatment ineffective. We previously found that pre-infusion with high MW free PEG (40 kDa) can serve as a decoy to saturate circulating APA, preventing binding to a subsequently administered dose of PEG-liposomes and restoring their prolonged circulation in mice, without any detectible toxicity. Here, we investigated the use of 40 kDa free PEG to restore the circulation of radio-labeled pegloticase in mice using longitudinal Positron Emission Tomography (PET) imaging over 4 days. Mice injected with pegloticase developed appreciable APA titers by Day 9, which further increased through Day 14. Compared to naive mice, mice with pegloticase-induced APA rapidly cleared 89Zr-labeled pegloticase, with ~75% lower pegloticase concentrations in the circulation at four hours after treatment. The 96-h AUC in APA+ mice was less than 30% of the AUC in naive mice. In contrast, pre-infusion of free PEG into PEG-sensitized mice restored the AUC of pegloticase to ~80% of that seen in naive mice, resulting in a similar biodistribution to pegloticase in naive mice over time. These results suggest that pre-infusion of free PEG may be a promising strategy to enable the safe and efficacious use of pegloticase and other PEGylated drugs in patients that have previously failed therapy due to induced APA.

RationaleAlthough COVID-19 is predominantly a respiratory tract infection, current antibody treatments are administered by systemic dosing. We hypothesize that inhaled delivery of a muco-trapping monoclonal antibody would provide a more effective and convenient treatment for COVID-19.ObjectiveWe investigated the safety, tolerability, and pharmacokinetics of IN-006, a reformulation of regdanvimab, an approved intravenous treatment for COVID-19, for nebulized delivery by a handheld nebulizer.MethodsA Phase 1 study was conducted in healthy volunteers. Study staff and participants were blinded to treatment assignment, except for pharmacy staff preparing the study drug. The primary outcomes were safety and tolerability. Exploratory outcomes were pharmacokinetic measurements of IN-006 in nasal fluid and serum.ResultsTwenty-three participants were enrolled and randomized across two single dose and one multiple dose cohorts. There were no serious adverse events (SAEs). All enrolled participants completed the study without treatment interruption or discontinuation. All treatment-emergent adverse events were transient, non-dose dependent, and were graded mild to moderate in severity. Nebulization was well tolerated and completed in a mean of 6 minutes in the high dose group. Mean nasal fluid concentrations of IN-006 in the multiple dose cohort were 921 µg/g of nasal fluid at 30 minutes after dosing and 5.8 µg/g at 22 hours. Mean serum levels in the multiple dose cohort peaked at 0.55 µg/mL at 3 days after the final dose.ConclusionsIN-006 was well-tolerated and achieved concentrations in the respiratory tract orders of magnitude above its inhibitory concentration. These data support further clinical development of IN-006.RegistrationAustralian New Zealand Clinical Trials Registry: ACTRN12621001235897

COVID-19, the disease caused by infection with SARS-CoV-2, requires urgent development of therapeutic interventions. Due to their safety, specificity, and potential for rapid advancement into the clinic, monoclonal antibodies (mAbs) represent a highly promising class of antiviral or anti-inflammatory agents. Herein, by analyzing prior efforts to advance antiviral mAbs for other acute respiratory infections (ARIs), we highlight the challenges faced by mAb-based immunotherapies for COVID-19. We present evidence supporting early intervention immediately following a positive diagnosis via inhaled delivery of mAbs with vibrating mesh nebulizers as a promising approach for the treatment of COVID-19., Graphical abstract Unlabelled Image, Highlights • Monoclonal antibodies (mAbs) represent a promising class of antiviral agents. • Systemically administered mAbs have previously failed to treat respiratory viruses. • Vibrating mesh nebulizers are routinely used in the home setting. • Treatment soon after diagnosis with nebulized mAbs may improve outcomes.

Childhood obesity is a major public health concern. However, predictors of successful outcomes for patients treated at multidisciplinary community hospital–based pediatric weight management programs remain poorly understood. We conducted a retrospective analysis to evaluate 633 pediatric patients from ages 2 to 18 at a tertiary pediatric weight management program in 2018. Predictors were evaluated in univariate comparisons, and significant variables were included in a linear regression analysis to identify factors associated with improvements in body mass index relative to the age- and sex-specific 95th percentile body mass index (%BMIp95). We found that male sex and increased number of clinical visits were independently and significantly associated with reductions in %BMIp95. Baseline %BMIp95, age, preferred language, and insurance status were not significant predictors of outcomes. A total of 398 (63%) patients experienced a decrease in %BMIp95 from baseline to follow-up. One quarter (24.8%) of patients experienced a decrease in %BMIp95 of at least 5%, a threshold associated with cardiometabolic improvements. Further, we observed significant improvements in cholesterol, triglycerides, alanine aminotransferase, aspartate aminotransferase, HbA1c, and waist circumference. These findings support a potential need for sex- and gender-tailored care as well as the benefits of increased access to pediatric weight management programs.

Immune responses against polyethylene glycol (PEG) can lead to the rapid clearance of PEGylated drugs and are associated with increased risk of serious adverse events such as infusion reactions and anaphylaxis. Although select PEGylated therapeutics can induce anti-PEG antibodies (APA), there is currently no readily deployable strategy to mitigate their negative effects. Given the large number of PEGylated therapeutics that are either FDA-approved or in clinical development, methods that suppress APA induction to ensure the safety and efficacy of PEGylated drugs in patients would be a valuable clinical tool. We previously showed that infusion of high molecular weight (MW) free PEG can safely and effectively restore the circulation of PEG liposomes in animals with high pre-existing titers of APA, without stimulating additional APA production. Here, we explored the effectiveness of prophylaxis with free PEG or tolerogenic PEGylated liposomes as a strategy to reduce the amount of APA induced by subsequently administered PEGylated liposomes. Surprisingly, we found that a single administration of free PEG alone was capable of markedly reducing the APA response to PEG-liposomes for ~2 months; the effectiveness was comparable to, and frequently exceeded, interventions with different tolerogenic PEG-liposomes. These results support further investigations of free PEG prophylaxis as a potential strategy to ameliorate the APA response to sensitizing PEGylated therapeutics.

To address the COVID-19 pandemic, there has been an unprecedented global effort to advance potent neutralizing mAbs against SARS-CoV-2 as therapeutics. However, historical efforts to advance antiviral monoclonal antibodies (mAbs) for the treatment of other respiratory infections have been met with categorical failures in the clinic. By investigating the mechanism by which SARS-CoV-2 and similar viruses spread within the lung, along with available biodistribution data for systemically injected mAb, we highlight the challenges faced by current antiviral mAbs for COVID-19. We summarize some of the leading mAbs currently in development, and present the evidence supporting inhaled delivery of antiviral mAb as an early intervention against COVID-19 that could prevent important pulmonary morbidities associated with the infection., Graphical abstract Unlabelled Image

Circulating antibodies that specifically bind polyethylene glycol (PEG), a polymer routinely used in protein and nanoparticle therapeutics, have been associated with reduced efficacy and increased adverse reactions to some PEGylated therapeutics. In addition to acute induction of anti-PEG antibodies (APA) by PEGylated drugs, typically low but detectable levels of APA are also found in up to 70% of the general population. Despite the broad implications of APA, the dynamics of APA-mediated clearance of PEGylated drugs, and why many patients continue to respond to PEGylated drugs despite the presence of pre-existing APA, remains not well understood. Here, we developed a minimal physiologically based pharmacokinetic (mPBPK) model that incorporates various properties of APA and PEGylated drugs. Our mPBPK model reproduced clinical PK data of APA-mediated accelerated blood clearance of pegloticase, as well as APA-dependent elimination of PEGyated liposomes in mice. Our model predicts that the prolonged circulation of PEGylated drugs will be compromised only at APA concentrations greater than ~500 ng/mL, providing a quantitative explanation to why the effects of APA on PEGylated treatments appear to be limited in most patients. This mPBPK model is readily adaptable to other PEGylated drugs and particles to predict the precise levels of APA that could render them ineffective, providing a powerful tool to support the development and interpretation of preclinical and clinical studies of various PEGylated therapeutics.

Emerging evidence suggests that the immune system can recognize polyethylene glycol (PEG), leading to the accelerated blood clearance (ABC) of PEGylated particles. Our aim here was to study the generation of anti-PEG immunity and changes in PEGylated microbubble pharmacokinetics during repeated contrast-enhanced ultrasound imaging in rats. We administered homemade PEGylated microbubbles multiple times over a 28-d period and observed dramatically accelerated clearance (4.2 × reduction in half-life), which was associated with robust anti-PEG IgM and anti-PEG IgG antibody production. Dosing animals with free PEG as a competition agent before homemade PEGylated microbubble administration significantly prolonged microbubble circulation, suggesting that ABC was largely driven by circulating anti-PEG antibodies. Experiments with U.S. Food and Drug Administration-approved Definity microbubbles similarly resulted in ABC and the generation of anti-PEG antibodies. Experiments repeated with non-PEGylated Optison microbubbles revealed a slight shift in clearance, indicating that immunologic factors beyond anti-PEG immunity may play a role in ABC, especially of non-PEGylated agents.

Antibodies against polyethylene glycol (PEG) can critically jeopardize the efficacy and safety of PEGylated therapeutics. For some PEG-drugs, a sizeable fraction of patients develop anti-PEG antibodies (APA), leading to reduced efficacy and potential adverse events. We surveyed physicians from several specialties to assess their awareness of APA. Overall, 83% of the physicians surveyed indicated that they have recently prescribed PEGylated drugs. Although 91% of respondents were aware of antidrug antibodies in general, only 22% were aware of APA responses. Further, there was limited awareness (35%) of PEG's inclusion in prescribed PEGylated therapeutics. These findings bring to light a need for improved awareness of APA, potentially via targeted education of physicians who prescribe specific PEGylated therapeutics that could induce or are otherwise affected by APA. Finally, it will be critical to quantitate the extent of knowledge transfer from the research community to clinicians, especially on topics of patient safety.

Antibodies that specifically bind polyethylene glycol (PEG), i.e. anti-PEG antibodies (APA), are associated with reduced efficacy and increased risk of serious adverse events for several PEGylated therapeutics. Here, we explored the concept of using free PEG molecules to saturate circulating APA. Surprisingly, we found that 40 kDa free PEG effectively restored the prolonged circulation of PEGylated liposomes in the presence of high titers of pre-existing APA for at least 48 h in mice. In contrast, lower molecular weight free PEG (≤10 kDa) failed to restore circulation beyond a few hours. These in vivo results were consistent with estimates from a minimal physiologically based pharmacokinetic model. Importantly, the infusion of free PEG appeared to be safe in mice previously sensitized by injection of PEGylated liposomes, and free PEG did not elicit excess APA production even in mice with pre-existing adaptive immunity against PEG. Our results support further investigation of high molecular weight free PEG as a potential method to control and overcome high titers of APA, restoring the prolonged circulation of PEGylated liposomes and possibly other PEGylated therapeutics.

Pretargeting is an increasingly explored strategy to improve nanoparticle targeting, in which pretargeting molecules that bind both selected epitopes on target cells and nanocarriers are first administered, followed by the drug-loaded nanocarriers. Bispecific antibodies (bsAb) represent a promising class of pretargeting molecules, but how different bsAb formats may impact the efficiency of pretargeting remains poorly understood, in particular Fab valency and Fc receptor (FcR)-binding of bsAb. We found the tetravalent bsAb markedly enhanced PEGylated nanoparticle binding to target HER2(+) cells relative to the bivalent bsAb in vitro. Pretargeting with tetravalent bsAb with abrogated FcR binding increased tumor accumulation of PEGylated liposomal doxorubicin (PLD) 3-fold compared to passively targeted PLD alone, and 5-fold vs pretargeting with tetravalent bsAb with normal FcR binding in vivo. Our work demonstrates that multivalency and elimination of FcRn recycling are both important features of pretargeting molecules, and further supports pretargeting as a promising nanoparticle delivery strategy.

Lipid-shelled microbubbles (MBs) are routinely used as contrast agents for ultrasound imaging. Such MBs are often formulated with polyethylene glycol (PEG), with the intention of shielding them from recognition and clearance by the innate immune system, prolonging their intravenous circulation time. Paradoxically, the immune system is able to generate specific antibodies that bind PEG. This has been associated with accelerated blood clearance of PEGylated particles when dosed repeatedly over multiple days. Here we aim to (1) study how PEGylated MB pharmacokinetics changes during repeat contrast-enhanced ultrasound imaging schedules and (2) investigate whether administration of these MBs generates an anti-PEG antibody response in rats.