Evaluation of serum cytokines and acute phase proteins as possible pharmacodynamic biomarkers to monitor endoscopic remission during ustekinumab therapy in patients with Crohn's disease

Background

Since not all Crohn's disease (CD) patients respond adequately to ustekinumab therapy, biomarkers could aid to monitor treatment response and optimize therapeutic outcomes.

Objectives

To explore the dynamics of serum biomarker concentrations to monitor the response to ustekinumab treatment in CD patients.

Design

Retrospective, exploratory study to evaluate concentrations of serum cytokines and acute phase proteins and their relation to endoscopic remission in CD patients during ustekinumab treatment.

Methods

Serum concentrations of 16 proteins including cytokines and acute phase proteins were measured using the Mesoscale Discovery Platform in serum of healthy controls (n = 13), and CD patients (n = 61) at baseline (week 0), week 8 and week 24 during ustekinumab treatment. Endoscopic remission was defined as simple endoscopic score for CD (SES-CD) <3 after 6 months of therapy.

Results

Absolute concentrations of serum amyloid A protein (SAA; week 8), IL-6 (week 24), AGP (weeks 8 and 24), interferon (IFN)-γ (weeks 8 and 24), lipopolysaccharide binding protein (LBP; weeks 8 and 24) and IL-22 (weeks 8 and 24) were significantly lower in endoscopic remitters compared to non-responders (p-values ranging between <0.001 and <0.05). SAA (week 8) and AGP (week 24) were the biomarkers with the highest area under the ROC curve (AUROC; 0.761 and 0.760, respectively) for identifying patients in endoscopic remission, though their performance was not superior to C-reactive protein (CRP) or faecal calprotectin. AUROCs of the predictive probability of biomarker combinations showed superiority in discriminating endoscopic remitters from non-responders in comparison to single biomarker measurements, but not as compared to faecal calprotectin.

Conclusion

Although not superior to faecal calprotectin, measurement of AGP, SAA, LBF, IFN-γ, IL-6 and IL-22 concentrations, and combinations thereof with or without CRP and faecal calprotectin, during ustekinumab therapy might contribute to adequate monitoring of treatment response in CD patients.

Exploring the Fate of Antibody-Encoding pDNA after Intramuscular Electroporation in Mice

DNA-based antibody therapy seeks to administer the encoding nucleotide sequence rather than the antibody protein. To further improve the in vivo monoclonal antibody (mAb) expression, a better understanding of what happens after the administration of the encoding plasmid DNA (pDNA) is required. This study reports the quantitative evaluation and localization of the administered pDNA over time and its association with corresponding mRNA levels and systemic protein concentrations. pDNA encoding the murine anti-HER2 4D5 mAb was administered to BALB/c mice via intramuscular injection followed by electroporation. Muscle biopsies and blood samples were taken at different time points (up to 3 months). In muscle, pDNA levels decreased 90% between 24 h and one week post treatment (p < 0.0001). In contrast, mRNA levels remained stable over time. The 4D5 antibody plasma concentrations reached peak levels at week two followed by a slow decrease (50% after 12 weeks, p < 0.0001). Evaluation of pDNA localization revealed that extranuclear pDNA was cleared fast, whereas the nuclear fraction remained relatively stable. This is in line with the observed mRNA and protein levels over time and indicates that only a minor fraction of the administered pDNA is ultimately responsible for the observed systemic mAb levels. In conclusion, this study demonstrates that durable expression is dependent on the nuclear uptake of the pDNA. Therefore, efforts to increase the protein levels upon pDNA-based gene therapy should focus on strategies to increase both cellular entry and migration of the pDNA into the nucleus. The currently applied methodology can be used to guide the design and evaluation of novel plasmid-based vectors or alternative delivery methods in order to achieve a robust and prolonged protein expression.

FLUIDOT: A Modular Microfluidic Platform for Single-Cell Study and Retrieval, with Applications in Drug Tolerance Screening and Antibody Mining

Advancements in lab-on-a-chip technologies have revolutionized the single-cell analysis field. However, an accessible platform for in-depth screening and specific retrieval of single cells, which moreover enables studying diverse cell types and performing various downstream analyses, is still lacking. As a solution, FLUIDOT is introduced, a versatile microfluidic platform incorporating customizable microwells, optical tweezers and an interchangeable cell-retrieval system. Thanks to its smart microfluidic design, FLUIDOT is straightforward to fabricate and operate, rendering the technology widely accessible. The performance of FLUIDOT is validated and its versatility is subsequently demonstrated in two applications. First, drug tolerance in yeast cells is studied, resulting in the discovery of two treatment-tolerant populations. Second, B cells from convalescent COVID-19 patients are screened, leading to the discovery of highly affine, in vitro neutralizing monoclonal antibodies against SARS-CoV-2. Owing to its performance, flexibility, and accessibility, it is foreseen that FLUIDOT will enable phenotypic and genotypic analysis of diverse cell samples and thus elucidate unexplored biological questions.

Clinically relevant dosing and pharmacokinetics of DNA-encoded antibody therapeutics in a sheep model

DNA-encoded delivery and in vivo expression of antibody therapeutics presents an innovative alternative to conventional protein production and administration, including for cancer treatment. To support clinical translation, we evaluated this approach in 18 40-45 kg sheep, using a clinical-matched intramuscular electroporation (IM EP) and hyaluronidase-plasmid DNA (pDNA) coformulation setup. Two cohorts of eight sheep received either 1 or 4 mg pDNA encoding an ovine anti-cancer embryonic antigen (CEA) monoclonal antibody (mAb; OVAC). Results showed a dose-response with average maximum serum concentrations of respectively 0.3 and 0.7 µg/ml OVAC, 4-6 weeks after IM EP. OVAC was detected in all 16 sheep throughout the 6-week follow-up, and no anti-OVAC antibodies were observed. Another, more exploratory, cohort of two sheep received a 12 mg pOVAC dose. Both animals displayed a similar dose-dependent mAb increase and expression profile in the first two weeks. However, in one animal, an anti-OVAC antibody response led to loss of mAb detection four weeks after IM EP. In the other animal, no anti-drug antibodies were observed. Serum OVAC concentrations peaked at 4.9 µg/ml 6 weeks after IM EP, after which levels gradually decreased but remained detectable around 0.2 to 0.3 µg/ml throughout a 13-month follow-up. In conclusion, using a delivery protocol that is currently employed in clinical Phase 1 studies of DNA-based antibodies, we achieved robust and prolonged in vivo production of anti-cancer DNA-encoded antibody therapeutics in sheep. The learnings from this large-animal model regarding the impact of pDNA dose and host immune response on the expressed mAb pharmacokinetics can contribute to advancing clinical translation.

Potent neutralizing anti-SARS-CoV-2 human antibodies cure infection with SARS-CoV-2 variants in hamster model

Treatment with neutralizing monoclonal antibodies (mAbs) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contributes to COVID-19 management. Unfortunately, SARS-CoV-2 variants escape several of these recently approved mAbs, highlighting the need for additional discovery and development. In a convalescent patient with COVID-19, we identified six mAbs, classified in four epitope groups, that potently neutralized SARS-CoV-2 D614G, beta, gamma, and delta infection in vitro, with three mAbs neutralizing omicron as well. In hamsters, mAbs 3E6 and 3B8 potently cured infection with SARS-CoV-2 Wuhan, beta, and delta when administered post-viral infection at 5 mg/kg. Even at 0.2 mg/kg, 3B8 still reduced viral titers. Intramuscular delivery of DNA-encoded 3B8 resulted in in vivo mAb production of median serum levels up to 90 μg/mL, and protected hamsters against delta infection. Overall, our data mark 3B8 as a promising candidate against COVID-19, and highlight advances in both the identification and gene-based delivery of potent human mAbs.

Biosimilar Use and Switching in Belgium: Avenues for Integrated Policymaking

Background: By improving the affordability and accessibility of biologicals, biosimilar competition provides important benefits to healthcare systems and patients. In Belgium, biosimilar uptake and competition is limited compared to other European markets. Whereas other countries have initiated structured biosimilar introduction or switching plans, no such framework or guiding principles are yet available in Belgium.

Objective: This study aims to develop recommendations that can inform policy action in Belgium on biosimilar use, especially in the context of switch decision-making, and this by drawing from the perspectives of healthcare professionals involved in procuring, prescribing, switching and dispensing biologicals including biosimilars.

Methods: This study made use of the consensus-building Nominal Group Technique, consisting of a three-step process 1) individual grading, 2) three structured Focus Group Discussions, 3) final individual grading involving an expert group of Belgian healthcare professionals (physician specialists and hospital pharmacists).

Results: Participants (n = 13) voiced challenges with the use of biosimilars and switching in practice, and a lack of incentives to use them. Six concrete areas for policy development to support stakeholders with biosimilar use and switch decision-making were identified: 1) address stakeholder hesitations regarding (multiple) switching, 2) provide meaningful incentives, 3) guide healthcare professionals with product decision-making, 4), align practical product modalities when possible, 5) involve healthcare professionals in policy making, and 6) provide practical switch support and patient information material, particularly in the ambulatory care setting. For each area, specific consensus-based recommendations were developed. Furthermore, a set of switch management and patient communication principles was derived, including amongst others, generating buy-in from involved stakeholders prior to switching and communicating with a one-voice message.

Conclusion: Without cohesive actions to reduce hurdles and without tangible benefits or steering mechanisms, changes in biosimilar use are unlikely in Belgium. To overcome this and stimulate market competitiveness, this study advances a set of concrete policy recommendations. At large, policy makers should develop an integrated policy framework, with a pro-active, best-value biological implementation roadmap that provides guidance and compelling measures to incentivize healthcare professionals to use biosimilars. Particular consideration should go to the ambulatory care setting, since drivers for biosimilar use are quasi absent in this context.

Novel ELISA for the specific detection of protease NEXIN-1 in human biological samples

Introduction

Serpin E2 or protease nexin‐1 (PN‐1) is a glycoprotein belonging to the serpin superfamily, whose function is closely linked to its ability to inhibit thrombin and proteases of the plasminergic system.

Objectives

In the absence of specific quantitative methods, an ELISA for the quantification of human PN‐1 was characterized and used in biological fluids.

Methods

The ELISA for human PN‐1 was developed using two monoclonal antibodies raised against human recombinant PN‐1. PN‐1 was quantified in plasma, serum, platelet secretion from controls and patients with hemophilia A and in conditioned medium of aortic tissue.

Results

A linear dose–response curve was observed between 2 and 35 ng/mL human PN‐1. Intra‐ and interassay coefficients of variation were 6.2% and 11.1%, respectively. Assay recoveries of PN‐1 added to biological samples were ≈95% in plasma, ≈97% in platelet reaction buffer, and ≈93% in RPMI cell culture medium. Levels of PN‐1 secreted from activated human platelets from controls was similar to that of patients with hemophilia A. PN‐1 could be detected in conditioned media of aneurysmal aorta but not in that of control aorta.

Conclusion

This is the first fully characterized ELISA for human serpin E2 level in biological fluids. It may constitute a relevant novel tool for further investigations on the pathophysiological role of serpin E2 in a variety of clinical studies.

Intratumoral DNA-based delivery of checkpoint-inhibiting antibodies and interleukin 12 triggers T cell infiltration and anti-tumor response

To improve the anti-tumor efficacy of immune checkpoint inhibitors, numerous combination therapies are under clinical evaluation, including with IL-12 gene therapy. The current study evaluated the simultaneous delivery of the cytokine and checkpoint-inhibiting antibodies by intratumoral DNA electroporation in mice. In the MC38 tumor model, combined administration of plasmids encoding IL-12 and an anti-PD-1 antibody induced significant anti-tumor responses, yet similar to the monotherapies. When treatment was expanded with a DNA-based anti-CTLA-4 antibody, this triple combination significantly delayed tumor growth compared to IL-12 alone and the combination of anti-PD-1 and anti-CTLA-4 antibodies. Despite low drug plasma concentrations, the triple combination enabled significant abscopal effects in contralateral tumors, which was not the case for the other treatments. The DNA-based immunotherapies increased T cell infiltration in electroporated tumors, especially of CD8⁺ T cells, and upregulated the expression of CD8⁺ effector markers. No general immune activation was detected in spleens following either intratumoral treatment. In B16F10 tumors, evaluation of the triple combination was hampered by a high sensitivity to control plasmids. In conclusion, intratumoral gene electrotransfer allowed effective combined delivery of multiple immunotherapeutics. This approach induced responses in treated and contralateral tumors, while limiting systemic drug exposure and potentially detrimental systemic immunological effects.

Regulatory Information and Guidance on Biosimilars and Their Use Across Europe: A Call for Strengthened One Voice Messaging

Background

Beyond evaluation and approval, European and national regulators have a key role in providing reliable information on biosimilars and the science underpinning their development, approval, and use.

Objectives

This study aims to (i) review biosimilar information and guidance provided by EMA and national medicines agencies and (ii) explore stakeholder perspectives on the role of regulators in enabling acceptance and use of biosimilars.

Methods

This study consists of (i) a comparative review of regulatory information and position statements across medicine agencies (n = 32) and (ii) qualitative interviews with stakeholders in Europe (n = 14).

Results

The comparative analysis showed that regulatory information and guidance about biosimilars offered by national medicines agencies in Europe varies, and is limited or absent in multiple instances. Approximately 40% (13/31) of the national medicines agencies' websites did not offer any information regarding biosimilars, and for about half (15/31) no educational materials were provided. Only less than half of national medicines agencies provided guidance on biosimilar interchangeability and switching (8/31 and 12/31, respectively). Among the national medicines agencies that did offer guidance, the extent (e.g., elaborate position vs. brief statement) and content (e.g., full endorsement vs. more cautious) of the guidance differed substantially. Countries that have a strong involvement in EU level biosimilar regulatory activities generally had more elaborate information nationally. Interviewees underwrote the need for (national) regulators to intensify biosimilar stakeholder guidance, especially in terms of providing clear positions regarding biosimilar interchangeability and switching, which in turn can be disseminated by the relevant professional societies more locally.

Conclusion

This study revealed that, despite strong EU-level regulatory biosimilar guidance, guidance about biosimilars, and their use differs considerably across Member States. This heterogeneity, together with the absence of a clear EU-wide position on interchangeability, may instill uncertainty among stakeholders about the appropriate use of biosimilars in practice. Regulators should strive for a clear and common EU scientific position on biosimilar interchangeability to bridge this gap and unambiguously inform policy makers, healthcare professionals, and patients. Furthermore, there is a clear opportunity to expand information at the national level, and leverage EU-developed information materials more actively in this regard.

Therapeutic drug monitoring in dermatology: the way towards dose optimization of secukinumab in chronic plaque psoriasis

Background

Despite the favourable efficacy profile of secukinumab, clinicians encounter varying clinical responses among patients potentially associated with under‐ and overdosing. As biologics are expensive, their rational use is crucial and evident. Therapeutic drug monitoring could guide clinicians in making decisions about treatment modifications.

Aim

In this multicentre, prospective study, we aimed to develop and validate a secukinumab immunoassay and searched for the therapeutic window in patients with psoriasis.

Methods

We determined secukinumab concentrations at trough in sera from 78 patients with psoriasis at multiple timepoints (Weeks 12, 24, 36, 48 and 52; after Week 52, measurements could be taken at an additional three timepoints) during maintenance phase, using an in‐house secukinumab immunoassay consisting of a combination of MA‐SEC66A2 as capture antibody and MA‐SEC67A9, conjugated to horseradish peroxidase, as detecting antibody. At each hospital visit, disease severity was assessed using the Psoriasis Area and Severity Index (PASI).

Results

After quantification, 121 serum samples were included for dose–response analysis. Based on a linear mixed‐effects model, secukinumab trough concentrations were found to decrease with increasing body mass index (BMI). Based on receiver operating characteristic (ROC) analysis, we concluded that the minimal effective secukinumab threshold was 39.1 mg/L in steady state, and that this was associated with a 92.7% probability of having an optimal clinical response (PASI ≤ 2 or reduction in PASI of ≥ 90%).

Conclusions

Monitoring and targeting a secukinumab trough concentration of 39.1 mg/L may be a viable treatment option in suboptimal responders. In patients with higher BMI, weight‐based dosing may be needed in order to prevent underdosing.

Both plasma basic carboxypeptidases, carboxypeptidase B2 and carboxypeptidase N, regulate vascular leakage activity in mice

BACKGROUND

Kallikrein is generated when the contact system is activated, subsequently cleaving high molecular weight kininogen to bradykinin (BK). BK binds to bradykinin receptor 2, causing vascular leakage. BK is inactivated by proteolysis by the plasma carboxypeptidase B2 and N (CPB2 and CPN). CPN is constitutively active but CPB2 is generated from its zymogen, proCPB2.

OBJECTIVES

Determine the role of CPB2 and CPN in the regulation of vascular leakage.

METHODS

Mice deficient in CPB2, CPN, or both (Cpb2-/- , Cpn-/- , and Cpb2-/- /Cpn-/- ) were compared with wild-type mice (WT) in a model of vascular leakage caused by skin irritation. In some experiments, mice were pretreated with antibodies that prevent activation of proCPB2.

RESULTS

Skin irritation increased vascular leakage most in Cpb2-/- /Cpn-/- , less in Cpb2-/- and Cpn-/- , and least in WT mice. There was no difference in vascular leakage without the challenge. Antibodies inhibiting activation of proCPB2 by plasmin, but not by the thrombin/thrombomodulin complex, increased vascular leakage to the level seen in Cpb2-/- mice. There was no change in levels of markers of coagulation and fibrinolysis.

CONCLUSIONS

Bradykinin is inactivated by both CPB2 and CPN independently. Plasmin is the activator of proCPB2 in this model. Mice lacking both plasma carboxypeptidases have more vascular leak than those lacking either alone. Although BK levels were not determined, BK is the likely substrate for CPB2 and CPN in this model.

Model-Informed Precision Dosing during Infliximab Induction Therapy Reduces Variability in Exposure and Endoscopic Improvement between Patients with Ulcerative Colitis

Model-informed precision dosing (MIPD) may be a solution to therapeutic failure of infliximab for patients with ulcerative colitis (UC), as underexposure could be avoided, and the probability of endoscopic improvement (pEI; Mayo endoscopic subscore ≤ 1) could be optimized. To investigate in silico whether this claim has merit, four induction dosing regimens were simulated: 5 mg/kg (label dosing), 10 mg/kg, covariate-based MIPD (fat-free mass, corticosteroid use, and presence of extensive colitis at baseline), and concentration-based MIPD (based on the trough concentration at day 14). Covariate- and concentration-based MIPD were chosen to target the same median area under the infliximab concentration-time curve up to endoscopy at day 84 (AUC_d84), as was predicted from 10 mg/kg dosing. Dosing at 5 mg/kg resulted in a mean ± standard deviation pEI of 55.7 ± 9.0%. Increasing the dose to 10 mg/kg was predicted to improve pEI to 65.1 ± 6.1%. Covariate-based MIPD reduced variability in exposure and pEI (65.1 ± 5.5%). Concentration-based MIPD decreased variability further (66.0 ± 3.9%) but did so at an increased average dose of 2293 mg per patient, as compared to 2168 mg for 10 mg/kg dosing. Mean pEI remained unchanged between 10 mg/kg dosing and MIPD, since the same median AUC_d84 was targeted. In conclusion, quantitative simulations predict MIPD will reduce variability in exposure and pEI between patients with UC during infliximab induction therapy.

Miniaturized single-cell technologies for monoclonal antibody discovery

Antibodies (Abs) are among the most important class of biologicals, showcasing a high therapeutic and diagnostic value. In the global therapeutic Ab market, fully-human monoclonal Abs (FH-mAbs) are flourishing thanks to their low immunogenicity and high specificity. The rapidly emerging field of single-cell technologies has paved the way to efficiently discover mAbs by facilitating a fast screening of the antigen (Ag)-specificity and functionality of Abs expressed by B cells. This review summarizes the principles and challenges of the four key concepts to discover mAbs using these technologies, being confinement of single cells using either droplet microfluidics or microstructure arrays, identification of the cells of interest, retrieval of those cells and single-cell sequence determination required for mAb production. This review reveals the enormous potential for mix-and-matching of the above-mentioned strategies, which is illustrated by the plethora of established, highly integrated devices. Lastly, an outlook is given on the many opportunities and challenges that still lie ahead to fully exploit miniaturized single-cell technologies for mAb discovery.

Improved Potency and Safety of DNA-Encoded Antibody Therapeutics Through Plasmid Backbone and Expression Cassette Engineering

DNA-encoded delivery of antibodies presents a labor- and cost-effective alternative to conventional antibody therapeutics. This study aims to improve the potency and safety of this approach by evaluating various plasmid backbones and expression cassettes. In vitro, antibody levels consistently improved with decreasing sizes of backbone, ranging from conventional to minimal. In vivo, following intramuscular electrotransfer in mice, the correlation was less consistent. While the largest conventional plasmid (10.2 kb) gave the lowest monoclonal antibody (mAb) levels, a regular conventional plasmid (8.6 kb) demonstrated similar levels as a minimal Nanoplasmid (6.8 kb). A reduction in size beyond a standard conventional backbone thus did not improve mAb levels in vivo. Cassette modifications, such as swapping antibody chain order or use of two versus a single encoding plasmid, significantly increased antibody expression in vitro, but failed to translate in vivo. Conversely, a significant improvement in vivo but not in vitro was found with a set of muscle-specific promoters, of which a newly engineered variant gave roughly 1.5- to 2-fold higher plasma antibody concentrations than the ubiquitous CAG promoter. In conclusion, despite the limited translation between in vitro and in vivo, we identified various clinically relevant improvements to our DNA-based antibody platform, both in potency and biosafety.

Population pharmacokinetic-pharmacodynamic model-based exploration of alternative ustekinumab dosage regimens for patients with Crohn's disease

AIMS

In the UNITI endoscopy sub-study, only 17.4% of patients with Crohn's disease (CD) on ustekinumab achieved endoscopic response and 10.9% of patients achieved endoscopic remission at week (w)44. We aimed to evaluate the impact of alternative ustekinumab dosage regimens on endoscopic outcomes based on population pharmacokinetic-pharmacodynamic (popPK-PD) modelling and simulation analysis.

METHODS

Real-world data were obtained from 83 patients with moderate-to-severe CD (95% biological-refractory) enrolled in a prospective cohort study receiving intravenous ustekinumab (~6 mg/kg) followed by every eight-week (q8w) subcutaneous maintenance therapy (90 mg). Three sequential models were developed: a two-compartment popPK model linking ustekinumab dose to ustekinumab exposure, an indirect response popPK-PD model describing the effect of ustekinumab exposure on fecal calprotectin (fCal), and a logistic regression outcome model linking fCal to endoscopic outcomes.

RESULTS

Ustekinumab clearance increased with decreasing serum albumin and increasing bodyweight. fCal decreased with increasing ustekinumab exposure. The probability of endoscopic response at w24 increased from 10.0% to 17.9% with fCal at w8 decreasing from 1800 μg/g to 694 μg/g (EC₅₀ ). The probability of endoscopic remission at w24 increased from 2.1% to 10.0% with fCal at w8 decreasing from 1800 μg/g to 214 μg/g (EC₅₀ ). Simulation-based comparison of q8w and q4w maintenance dosing regimens predicted 16.7% and 22.2% endoscopic response rates, respectively. Endoscopic remission rates were estimated to be 4.2% on q8w dosing and 6.7% on q4w dosing.

CONCLUSIONS

The developed models can guide clinical trial design and support model-informed dose optimization (stratified or individualized dosing) to improve endoscopic outcomes.

Tissue Exposure does not Explain Non-Response in Ulcerative Colitis Patients with Adequate Serum Vedolizumab Concentrations

BACKGROUND AND AIMS

Some patients with ulcerative colitis [UC] do not respond to vedolizumab treatment despite adequate drug exposure in serum. This study aimed to investigate vedolizumab in tissue and questioned whether insufficient tissue exposure could explain non-response in UC patients with adequate serum vedolizumab concentrations.

METHODS

A paired serum sample and colonic mucosal biopsy was collected from 40 UC patients [20 endoscopic responders, 20 non-responders] at week 14 of vedolizumab treatment. Vedolizumab, soluble [s]-mucosal addressin cell adhesion molecule-1 [MAdCAM-1], s-vascular cell adhesion molecule-1 [VCAM-1] and s-intercellular adhesion molecule-1 [ICAM-1] were measured in serum and/or tissue. Endoscopic response was defined as Mayo endoscopic sub-score ≤1.

RESULTS

A significant positive correlation was observed between vedolizumab serum and colonic tissue concentrations [ρ = 0.84, p < 0.0001], regardless of the macroscopic inflammatory state of the tissue. Vedolizumab tissue concentrations were lower in non-responders than in responders [0.07 vs 0.11 µg/mg, p = 0.04]. In the subgroup of patients with adequate vedolizumab serum concentrations [>14.6 µg/mL], tissue vedolizumab was not significantly different between responders and non-responders [0.15 vs 0.13 µg/mg; p = 0.92]. Serum sMAdCAM-1 concentrations, but not serum sICAM-1 or sVCAM-1 concentrations, were significantly higher in responders than in non-responders with adequate vedolizumab serum concentrations [1.04 vs 0.83 ng/mL, p = 0.03].

CONCLUSIONS

Vedolizumab concentrations in colonic mucosal tissue of UC patients reflect the concentration in serum regardless of the macroscopic inflammatory state of the tissue. Our data show that insufficient tissue exposure does not explain non-response in UC patients with adequate serum vedolizumab concentrations.

Knowledge and perception of biosimilars in ambulatory care: a survey among Belgian community pharmacists and physicians

Background

With the approval of biosimilars for subcutaneously administered products, such as adalimumab, etanercept and insulin, biosimilars become increasingly available in ambulatory care. Little is known about the knowledge and attitudes of healthcare providers who are in charge of dispensing and prescribing biosimilars in this context. This study aims to assess the knowledge and perception about biosimilars among community pharmacists and physicians.

Methods

Belgian community pharmacists (n = 177) and physicians (n = 30) were surveyed on their knowledge, experience with dispensing/prescribing biologicals including biosimilars, perception regarding interchangeability, switching and substitution and informational and educational needs. Descriptive and statistical analyses were performed.

Results

Only 32% of community pharmacists and 52% of physicians had yet dispensed/prescribed a biosimilar. Approximately 35% of community pharmacists felt insufficiently trained to counsel patients with biosimilar therapy, which was significantly higher compared to their self-assessed competence to counsel patients with biological therapy in general (p = 0.023). Community pharmacists experienced questions about similarity between reference products and biosimilars (47%) and their interchangeability (42%). Over 40% of physicians found patient uncertainty about efficacy and safety challenging when prescribing biosimilars. A similar proportion of physicians would only prescribe a biosimilar in indications for which the biosimilar has been tested clinically. The majority of pharmacists (58%) was in favor of substitution of biologicals, on the condition that the prescriber would be contacted. Also over 40% of physicians was open to this approach in case of substitution. Educational support, budget for additional staff and transparency about savings were considered suitable stimuli to incentivize biosimilar use. The need for information about biologicals including biosimilars was nearly unanimous among community pharmacists. Also 67% of physicians requested more information. Both community pharmacists and physicians preferred to be informed by their respective professional associations.

Conclusions

This study showed a substantial need for targeted educational measures to increase the knowledge and confidence about both biological medicines in general and biosimilars in particular among Belgian community pharmacists and physicians. The results may inform educational and policy measures to stimulate biosimilar use in ambulatory care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40545-021-00330-x.

The Efficacy, Safety, and Immunogenicity of Switching Between Reference Biopharmaceuticals and Biosimilars: A Systematic Review

To date, no consensus exists among stakeholders about switching patients between reference biological products (RPs) and biosimilars, which may have been curbing the implementation of biosimilars in clinical practice. This study synthesizes the available data on switching and assesses whether switching patients from a RP to its biosimilar or vice versa affects efficacy, safety, or immunogenicity outcomes. A total of 178 studies, in which switch outcomes from a RP to a biosimilar were reported, was identified. Data were derived from both randomized controlled trials and real-world evidence. Despite the limitations stemming from a lack of a robust design for most of the studies, the available switching data do not indicate that switching from a RP to a biosimilar is associated with any major efficacy, safety, or immunogenicity issues. Some open-label and observational studies reported increased discontinuation rates after switching, which were mainly attributed to nocebo effects. Involvement of the prescriber in any decision to switch should remain and attention should be paid to the mitigation of a potential nocebo effect.

Expanding a Portfolio of (FO-) SPR Surface Chemistries with the Co(III)-NTA Oriented Immobilization of His6-Tagged Bioreceptors for Applications in Complex Matrices

Cobalt-nitrilotriacetic acid (Co(III)-NTA) chemistry is a recognized approach for oriented patterning of His₆-tagged bioreceptors. We have applied the matching strategy for the first time on a surface plasmon resonance (SPR) platform, namely, the commercialized fiber optic (FO)-SPR. To accomplish this, His₆-tagged bioreceptor (scFv-33H1F7) and its target PAI-1 were used as a model system, after scrutinizing the specificity of their interaction. When benchmarked to traditional carboxyl-based self-assembled monolayers (SAM), NTA allowed (1) more efficient FO-SPR surface coverage with bioreceptors compared with the former and (2) realization of thus far difficult-to-attain label-free bioassays on the FO-SPR platform in both buffer and 20-fold diluted human plasma. Moreover, Co(III)-NTA surface proved to be compatible with traditional gold nanoparticle-mediated signal amplification in the buffer as well as in 10-fold diluted human plasma, thus expanding the dynamic detection range to low ng/mL. Both types of bioassays revealed that scFv-33H1F7 immobilized on the FO-SPR surface using different concentrations (20, 10, or 5 μg/mL) had no impact on the bioassay sensitivity, accuracy, or reproducibility despite the lowest concentration effectively resulting in close to 20% fewer bioreceptors. Collectively, these results highlight the importance of Co(III)-NTA promoting the oriented patterning of bioreceptors on the FO-SPR sensor surface for securing robust and sensitive bioassays in complex matrices, both in label-free and labeled formats.

Nonmedical Switching From Originators to Biosimilars: Does the Nocebo Effect Explain Treatment Failures and Adverse Events in Rheumatology and Gastroenterology?

The act of nonmedical switching, defined as switching stable patients who are generally doing well with their current therapy from an originator biologic to its biosimilar, has been endorsed as a reasonable treatment strategy. The safety and efficacy of nonmedical switching have been evaluated in randomized controlled and real-world evidence studies, which have demonstrated that although many patients maintain treatment response after the switch, some patients experience therapy failure, resulting in therapy discontinuation. It has been postulated that the vast majority, if not all, of these treatment failures result from a "nocebo effect", defined as patients' negative expectations toward the therapy change. Reports suggest that the risk of a nocebo effect is higher following a mandated nonmedical switch. Although the nocebo effect is a well-recognized phenomenon in pain studies, evidence is limited in immune-mediated diseases primarily because it is difficult to quantify, especially retrospectively. In spite of this, numerous biosimilar studies in patients with immune-mediated diseases have concluded that nonmedical switching failures are due to a nocebo effect. The objective of this narrative review was to explore the reasons for nonmedical switch failure or discontinuation and the role of the nocebo effect among patients with inflammatory rheumatic and gastrointestinal diseases who switched from an originator biologic to its biosimilar.

DNA-Based Delivery of Checkpoint Inhibitors in Muscle and Tumor Enables Long-Term Responses with Distinct Exposure

Checkpoint-inhibiting antibodies elicit impressive clinical responses, but still face several issues. The current study evaluated whether DNA-based delivery can broaden the application of checkpoint inhibitors, specifically by pursuing cost-efficient in vivo production, facilitating combination therapies, and exploring administration routes that lower immune-related toxicity risks. We therefore optimized plasmid-encoded anti-CTLA-4 and anti-PD-1 antibodies, and studied their pharmacokinetics and pharmacodynamics when delivered alone and in combination via intramuscular or intratumoral electroporation in mice. Intramuscular electrotransfer of these DNA-based antibodies induced complete regressions in a subcutaneous MC38 tumor model, with plasma concentrations up to 4 and 14 μg/mL for anti-CTLA-4 and anti-PD-1 antibodies, respectively, and antibody detection for at least 6 months. Intratumoral antibody gene electrotransfer gave similar anti-tumor responses as the intramuscular approach. Antibody plasma levels, however, were up to 70-fold lower and substantially more transient, potentially improving biosafety of the expressed checkpoint inhibitors. Intratumoral delivery also generated a systemic anti-tumor response, illustrated by moderate abscopal effects and prolonged protection of cured mice against a tumor rechallenge. In conclusion, intramuscular and intratumoral DNA-based delivery of checkpoint inhibitors both enabled long-term anti-tumor responses despite distinct systemic antibody exposure, highlighting the potential of the tumor as delivery site for DNA-based therapeutics.

Different Policy Measures and Practices between Swedish Counties Influence Market Dynamics: Part 2-Biosimilar and Originator Etanercept in the Outpatient Setting

Background

Diverging approaches towards market entry and uptake of biosimilars, even within a country, leads to regional variation in biosimilar use. This is the case in Sweden, where the 21 county councils control the healthcare budget and offer regional guidance.

Objectives

This study aimed to analyse the market dynamics of originator and biosimilar etanercept (outpatient setting) in the different counties of Sweden, and examine the influence of local policy measures and practices, in addition to national policy.

Methods

This study was performed in three steps: (1) a structured review of the literature on (biosimilar) policies in Sweden; (2) analysis of market data on the counties’ originator and biosimilar etanercept uptake (quarter two 2012 to quarter four 2017) provided by IQVIA™; and (3) discussion of findings in face-to-face semi-structured interviews with the national pricing and reimbursement agency, key experts in the county councils of Skåne, Västra Götaland and Stockholm, and an industry representative.

Results

Notwithstanding the existence of a national managed entry agreement for etanercept, wide variations in biosimilar market shares between counties were observed (40–82% in 2017). Over time, early and late adopters of biosimilar etanercept can be distinguished. In quarter four 2017, biosimilar market shares of all counties slightly decreased in accordance with the lower priced originator product from 1 October 2017. As prescriptions for treatment with etanercept are often provided for a year, two approaches are possible to switch patients: active pullback of prescriptions resulting in additional workload, or wait until the patient’s next visit. Qualitative analysis indicated that the choice to use the biosimilar or the originator product depends on differences in rebated prices of the biosimilar and originator product, the presence of key opinion leaders, local guidelines, and financial streams and local gainsharing arrangements. Our estimates of current rebated prices and costs after gainsharing for the county councils and Government reveal only limited price differences between products.

Conclusions

Regional variations in use of biosimilar etanercept can be seen although prices are coordinated nationally. This suggests that counties react differently to price differences and highlights the role of local policy and attitudes of stakeholders towards biosimilars and switching. It seems that some counties are hesitant to switch patients, as it is associated with an increased administrative workload that might not be compensated for by savings associated with a lower priced product.

The rise of oncology biosimilars: from process to promise

Biosimilars are biologic products that are highly similar to, and have no clinically meaningful differences from, the approved originator molecule. They are poised to play an increasingly central role in cancer treatment, helping to improve access by driving down costs. Regulatory bodies have set out robust mechanisms for the approval of biosimilars, based on comprehensive and rigorous analytical and nonclinical comparisons with the originator. Product attributes (e.g., post-translational modifications) that are important to the function of the molecule must be similar between biosimilar and originator. This should be followed by a robust clinical development program, assessing pharmacokinetics, pharmacodynamics, efficacy, safety and immunogenicity. Equivalence in one indication might allow extrapolation across all the indications of the originator biologic. The recent approval of several trastuzumab biosimilars provides an example of how this process can work in practice for the benefit of patients, clinicians and payers.

Bridging the Clinical Gap for DNA-Based Antibody Therapy Through Translational Studies in Sheep

Clinical translation of DNA-based administration of monoclonal antibodies (mAbs) is uncertain due to lack of large animal data. To bridge the clinical gap, we evaluated a panel of novel plasmid DNA (pDNA)-encoded mAbs in 40-70 kg sheep with a clinical intramuscular electroporation protocol. Injection of 4.8 mg of pDNA, encoding ovine anti-human CEA mAb (OVAC), led to peak plasma mAb titers of 300 ng/mL. OVAC remained detectable for 3 months and was boosted by a second pOVAC administration. Hyaluronidase muscle pretreatment increased OVAC concentrations up to 10-fold. These higher plasma titers, however, led to anti-drug antibodies (ADAs) toward the OVAC variable regions, resulting in loss of mAb detection and of adequate redosing. Transient immune suppression avoided ADA formation, with OVAC peaking at 3.5 μg/mL and remaining detectable for 11 months after pOVAC injection. DNA-based delivery of ovine anti-human EGFR mAb (OVAE), identical to OVAC except for the variable regions, preceded by hyaluronidase, allowed for at least three consecutive administrations in an immune-competent sheep, without ADA response. When tripling the pOVAE dose to 15 mg, transient ADAs of limited impact were observed; plasma OVAE peaked at 2.6 μg/mL and was detected up to 7 months. DNA-based anti-HER2 trastuzumab in sheep gave no detectable mAb concentrations despite previous validation in mice, highlighting the limitations of relying on small-rodent data only. In conclusion, our results highlight the potential and caveats of clinical DNA-based antibody therapy, can expedite preclinical and clinical development, and benefit the field of gene transfer as a whole.

The arrival of biosimilar monoclonal antibodies in oncology: clinical studies for trastuzumab biosimilars

The monoclonal antibody trastuzumab (Herceptin®), which targets the human epidermal growth factor receptor 2 (HER2), is approved for the treatment of early breast and advanced breast and gastric cancer in which HER2 is overexpressed. Several biosimilar versions of trastuzumab are expected to enter the European market over the course of 2018 and 2019. The biosimilar development pathway consists of a comprehensive comparability exercise between the biosimilar candidate and the reference product, primarily focussing on data from analytical studies. Clinical studies for biosimilar candidates follow a different design to those for a new biological, as the aim is not to independently establish clinical benefit, but to confirm biosimilarity between the two agents. The different trastuzumab biosimilar candidates have followed diverse pathways in their clinical development, with differences in clinical trial design (equivalence or non-inferiority design), patient population (those with metastatic or early breast cancer) and endpoint (overall response rate or pathological complete response). These differences in approach in phase 3 testing must be viewed in the totality of evidence demonstrating biosimilarity. Adequate information on the biosimilar approval pathway, the nature of the biosimilarity exercise and how the clinical development of a biosimilar is tailored to meet the licensing requirements can help informed decision making in clinical practice.

Immunogenicity of immunomodulatory, antibody-based, oncology therapeutics

The increasing use of multiple immunomodulatory (IMD) agents for cancer therapies (e.g. antibodies targeting immune checkpoints, bispecific antibodies, and chimeric antigen receptor [CAR]-T cells), is raising questions on their potential immunogenicity and effects on treatment. In this review, we outline the mechanisms of action (MOA) of approved, antibody-based IMD agents, potentially related to their immunogenicity, and discuss the reported incidence of anti-drug antibodies (ADA) as well as their clinical relevance in patients with cancer. In addition, we discuss the impact of the administration route and potential strategies to reduce the incidence of ADA and manage treated patients. Analysis of published reports indicated that the risk of immunogenicity did not appear to correlate with the MOA of anti-programmed death 1 (PD-1)/PD-ligand 1 monoclonal antibodies nor to substantially affect treatment with most of these agents in the majority of patients evaluated to date. Treatment with B-cell depleting agents appears associated with a low risk of immunogenicity. No significant difference in ADA incidence was found between the intravenous and subcutaneous administration routes for a panel of non-oncology IMD antibodies. Additionally, while the data suggest a higher likelihood of immunogenicity for antibodies with T-cell or antigen-presenting cell (APC) targets versus B-cell targets, it is possible to have targets expressed on APCs or T cells and still have a low incidence of immunogenicity.

Demystifying biosimilars: development, regulation and clinical use

Biologics are an integral component in the treatment of various diseases. However, limited patient access to these medicines remains a significant global challenge, prompting development of safe and effective biosimilars. A biosimilar is 'highly similar to a reference (originator) product, for which there are no clinically meaningful differences between the two products in terms of safety, purity and potency'. Biosimilars have the potential to offer possible benefits, including lower treatment costs, thereby increasing patient access and clinical use, which may lead to better overall outcomes. Improved understanding of biosimilars may enhance confidence and trust in these agents. As increasing numbers of biosimilars achieve regulatory approval, this overview aims to address enduring knowledge gaps regarding the development and use of biosimilars.

Atherothrombosis and Thromboembolism: Position Paper from the Second Maastricht Consensus Conference on Thrombosis

Atherothrombosis is a leading cause of cardiovascular mortality and long-term morbidity. Platelets and coagulation proteases, interacting with circulating cells and in different vascular beds, modify several complex pathologies including atherosclerosis. In the second Maastricht Consensus Conference on Thrombosis, this theme was addressed by diverse scientists from bench to bedside. All presentations were discussed with audience members and the results of these discussions were incorporated in the final document that presents a state-of-the-art reflection of expert opinions and consensus recommendations regarding the following five topics: 1. Risk factors, biomarkers and plaque instability: In atherothrombosis research, more focus on the contribution of specific risk factors like ectopic fat needs to be considered; definitions of atherothrombosis are important distinguishing different phases of disease, including plaque (in)stability; proteomic and metabolomics data are to be added to genetic information. 2. Circulating cells including platelets and atherothrombosis: Mechanisms of leukocyte and macrophage plasticity, migration, and transformation in murine atherosclerosis need to be considered; disease mechanism-based biomarkers need to be identified; experimental systems are needed that incorporate whole-blood flow to understand how red blood cells influence thrombus formation and stability; knowledge on platelet heterogeneity and priming conditions needs to be translated toward the in vivo situation. 3. Coagulation proteases, fibrin(ogen) and thrombus formation: The role of factor (F) XI in thrombosis including the lower margins of this factor related to safe and effective antithrombotic therapy needs to be established; FXI is a key regulator in linking platelets, thrombin generation, and inflammatory mechanisms in a renin-angiotensin dependent manner; however, the impact on thrombin-dependent PAR signaling needs further study; the fundamental mechanisms in FXIII biology and biochemistry and its impact on thrombus biophysical characteristics need to be explored; the interactions of red cells and fibrin formation and its consequences for thrombus formation and lysis need to be addressed. Platelet-fibrin interactions are pivotal determinants of clot formation and stability with potential therapeutic consequences. 4. Preventive and acute treatment of atherothrombosis and arterial embolism; novel ways and tailoring? The role of protease-activated receptor (PAR)-4 vis à vis PAR-1 as target for antithrombotic therapy merits study; ongoing trials on platelet function test-based antiplatelet therapy adjustment support development of practically feasible tests; risk scores for patients with atrial fibrillation need refinement, taking new biomarkers including coagulation into account; risk scores that consider organ system differences in bleeding may have added value; all forms of oral anticoagulant treatment require better organization, including education and emergency access; laboratory testing still needs rapidly available sensitive tests with short turnaround time. 5. Pleiotropy of coagulation proteases, thrombus resolution and ischaemia-reperfusion: Biobanks specifically for thrombus storage and analysis are needed; further studies on novel modified activated protein C-based agents are required including its cytoprotective properties; new avenues for optimizing treatment of patients with ischaemic stroke are needed, also including novel agents that modify fibrinolytic activity (aimed at plasminogen activator inhibitor-1 and thrombin activatable fibrinolysis inhibitor.

Modulation of Plasminogen Activator Inhibitor 1 by Triton X-100 – Identification of Two Consecutive Conformational Transitions

Plasminogen activator inhibitor-1 (PAI-1) is a unique member of the serpin superfamily because of its conformational and functional flexibility. In the present study, we have evaluated the influence of the nonionic detergent Triton X-100 (TX-100) on the functional stability and conformational transitions of PAI-1.

At 37° C, TX-100 induced a concentration-dependent decrease of the functional half-life of PAI-1 resulting in half-lives of 177 ± 54 min (mean ± SD, n = 3), 19 ± 2 min, 1.7 ± 0.3 min and 0.53 ± 0.03 min in the presence of 0.005, 0.010, 0.020 and 0.2% TX-100, respectively, compared to a half-life of 270 ± 146 min in the absence of TX-100. Conformational analysis at various time points and at different temperatures (0° C, 25° C, 37° C) revealed that this inactivation proceeds through the formation of a substrate-like intermediate followed by the formation of the latent form. Kinetic evaluation demonstrated that this conversion fits to two consecutive first-order transitions, i.e. active substrate latent. The k1 value was strongly dependent on the concentration of TX-100 (e.g. 0.002 ± 0.0006 s -1 and 0.029 ± 0.003 s -1 for 0.01% and 0.2% TX-100 at 37° C) whereas the conversion of substrate to latent (k2) was virtually independent of the TX-100 concentration (i.e. 0.012 ± 0.002 s -1 and 0.011 ± 0.001 s -1 for 0.01 and 0.2% TX-100 at 37° C).

Experiments with a variety of other non-ionic amphiphilic compounds revealed that the amphiphilic character of the compound is, at least in part, responsible for the observed effects and strongly indicate that the currently reported mechanism of inactivation is of general importance for the conformational transitions in PAI-1.

In conclusion, TX-100 changes the initial conformation of PAI-1 resulting in altered functional properties. This observation allows us to develop a new model for the mechanism involved in the conformational flexibility of PAI-1 and may provide new insights for the development of strategies for interference with PAI-1 activity.

Effect of Stabilizing versus Destabilizing Interactions on Plasminogen Activator Inhibitor-1

Plasminogen activator inhibitor-1 (PAI-1) is a unique member of the serpin family, as it spontaneously converts into a latent conformation. However, the exact mechanism of this conversion is not known. Previous studies reported that neutralizing monoclonal antibodies as well as reversal or removal of charges on the s3C-s4C turn results in a destabilization of PAI-1 leading to an accelerated conversion to its latent form.

In this study the effect of the reversal or removal of charges in this “gate region” (R186E/R187E, H190E/K191E, H190L/K191L and R356E) on a stable PAI-1-variant (PAI-1-stab) was investigated. Whereas PAI-1-stab has a half-life of 150 ± 66 h, PAI-1-stab-R186ER187E, PAI-1-stab-H190E-K191E, PAI-1-stab-H190L-K191L and PAI-1-stab-R356E have a strongly decreased half-life (p< 0.005 versus PAI-1-stab) of 175 ± 48 min, 75 ± 34 min, 68 ± 38 min and 79 ± 16 min, respectively. Wild-type PAI-1 (wtPAI-1) had a half-life of 55 ± 19 min. These data indicate that the stabilization induced by the mutated residues in PAI-1-stab is counteracted by the additional mutations, resulting in half-lives similar to that of wtPAI-1, thereby suggesting that the stabilizing and destabilizing forces act mainly independently in these mutants. Extrapolation of these data to other (stable) serpins leads to the hypothesis that the s3C-s4C turn and the distal hinge region of the reactive site loop plays a role for the stability of serpins in general.

Immunoassays for the Quantitation of Porcine PAI-1 Antigen and Activity in Biological Fluid Samples

Two monoclonal antibody-based enzyme-linked immunosorbent assays (ELISAs) for the quantitation of porcine plasminogen activator inhibitor-1 (PAI-1) antigen and activity in plasma were constructed and validated. The intra-assay, interassay, and interdilution coefficients of variation were 4.3, 13, and 8%, respectively, for the antigen ELISA and 5, 16, and 11% for the activity assay. Assay recoveries, in the antigen ELISA, of either latent or active recombinant porcine PAI-1 (10 and 50 ng/ml) added to plasma were 86 ± 9% and 92 ± 22%, respectively, for the latent form and 89 ± 9% and 87 ± 7% for the active form (mean ± SD, n = 3 to 4). In the immunofunctional assay, recoveries for the same concentrations of active PAI-1 were 108 ± 16% and 92 ± 21%, respectively. In male porcine plasma the level of PAI-1 antigen was 31 ± 11 ng/ ml and the activity, 34 ± 16 ng/ml (mean ± SD, n = 10). In female plasma PAI-1 antigen levels were 20 ± 5.2 ng/ml and the PAI-1 activity 42 ± 17 ng/ml (n = 13). A linear correlation was found between PAI-1 antigen and activity levels in male (r = 0.60) and female (r = 0.70) plasma. Immunodepletion resulted in a decrease of >95% of the original PAI-1 antigen or activity levels. Incubation of plasma samples at 37° C for 16 h resulted in a significant decrease (70 to 85%) of PAI-1 activity. Under these conditions (37° C, 16 h) PAI-1 antigen levels remained unchanged in males whereas the response of the female samples in the PAI-1 antigen assay increased two-fold.

In lysed platelet-rich plasma males had 990 ± 470 ng/ml antigen and 160 ± 80 ng/ml activity and females, 920 ± 500 ng/ml antigen and 150 ± 98 ng/ml activity corresponding to 2.1 ± 0.77 fg PAI-1 antigen per platelet. Only 16% of PAI-1 released from platelets was found to be active. Linear correlations between PAI-1 antigen and activity were found for both males (r = 0.61) and females (r = 0.67).

The assays are both sensitive and specific and may, therefore, aid the elucidation of the pathophysiological role of PAI-1 in swine experimental models of atherosclerosis and other thrombotic disorders.

Prevention of Renal Fibrin Deposition in Endotoxin-induced DIC through Inhibition of PAI-1

Plasminogen activator inhibitor-1 (PAI-1) increases in endotoxemia thus possibly cooperating in altering the hemostatic balance in a prothrombotic direction. The effect of the inhibition of PAI-1 with the monoclonal antibody MA-33B8 was studied systemically and in kidneys in a lapine model of endotoxin-induced disseminated intravascular coagulation (DIC). The increase in plasmatic PAI activity in the control group (n = 9) was inhibited in the MA-33B8 treated rabbits (n = 5). Control rabbits showed renal fibrin deposits, whereas only one of the MA-33B8 rabbits did so. These results were confirmed immunohistochemically in kidneys as PAI-1 immunostaining was seen inside the glomeruli and larger vessels in the control group, whereas MA-33B8 rabbits showed a remarkable decrease, demonstrating that MA-33B8 successfully inhibited PAI-1 in the kidneys as well. Therefore evidence for the important role of PAI-1 in fibrin generation in endotoxin-induced DIC is presented, suggesting that strategies aiming at its reduction can be useful in this pathology.

Characterization and Comparative Evaluation of a Novel PAI-1 Inhibitor

Plasminogen activator inhibitor-1 (PAI-1), the primary physiological inhibitor of both tissue-type plasminogen activator and urokinasetype plasminogen activator in plasma, is a well established risk factor in thrombotic diseases. Reduction of active PAI-1 levels may lead to a decreased tendency of thrombosis. Compounds that can suppress pharmacologically active PAI-1 levels are therefore considered as putative drugs.

In the present study, we describe the PAI-1 neutralizing properties and mechanism of a newly selected compound (i. e. fendosal, HP129) in comparison to four previously reported compounds (i. e. AR-H029953XX, XR1853, XR5118 and the peptide TVASS) using different assays. The inhibitory effect of these compounds on active PAI-1 was analyzed by a plasmin-coupled chromogenic assay (Coaset® t-PA), direct chromogenic assays (t-PA, u-PA) and quantification of complex formation by ELISA, SDS-PAGE and surface plasmon resonance. Comparative evaluation of the obtained IC50 values reveals large differences [i. e. IC50 of 15 µM (HP129) vs. >1000 µM (XR5118) determined at 37° C using SDS-PAGE] between the compounds studied.

Importantly, the relative potency of the various compounds is also dependent on the method used (10 to 170-fold differences in IC50 values). Characterization of the PAI-1 forms (i. e. active, non-reactive and substrate) generated upon inactivation reveals that the newly described compound HP129 induces a unique pathway (i. e. active to non-reactive conversion via a substrate-behaving intermediate) of inactivation compared to the other compounds.

Taken together, these data strongly suggest that the various compounds act through different mechanisms. In addition, the results stress the necessity for a careful selection of the method used for the evaluation of PAI-1 inhibitors, preferably requiring a panel of screening methods.

Elucidation of the paratope of scFv-8H9D4, a PAI-1 neutralizing antibody derivative

Interfering with increased levels of plasminogen activator inhibitor-1 (PAI-1) might offer new therapeutic strategies for a variety of cardiovascular diseases. Inactivation of PAI-1 can be accomplished by a number of monoclonal antibodies (MA), including MA-8H9D4. In a previous study, a single-chain variable fragment (scFv-8H9D4) was cloned and found to have the same properties as the parental MA-8H9D4. In the present study, we identified the residues of scFv-8H9D4 that contribute significantly to the paratope. The complementarity determining region 3 from the heavy (H3) and the light (L3) chain were analysed through site-directed mutagenesis. Out of twelve mutations, only four residues appeared to contribute to the paratope. The affinity of scFv-8H9D4-H3-L97D for PAI-1 was 38-fold decreased (KA = 4.8 ± 0.2 × 107 M–1 vs. 1.8 ± 0.7 × 109 M–1 for scFv-8H9D4) whereas scFv-8H9D4-H3-R98Y did not bind to PAI-1. The affinities of scFv-8H9D4-L3-Y91S and scFv-8H9D4-L3-F94D for PAI-1 were 9- and 5-fold reduced, respectively, whereas the combined mutation resulted in an 86-fold decreased affinity (KA = 2.1 ± 0.2 × 107 M–1).In accordance with the affinity data, these mutants had no, or a reduced, PAI-1 inhibitory capacity, confirming that these four particular residues form the major interaction site of scFv-8H9D4 with PAI-1. In combination with the three-dimensional structure, these data contribute to the rational design of PAI-1 neutralizing compounds.

Immunological Quantitation of Rabbit Plasminogen Activator Inhibitor-1 in Biological Samples

Two immunoassays for the specific quantitation of rabbit plasminogen activator inhibitor-1 (PAI-1) antigen and activity in biological samples were developed and applied for the evaluation of PAI-1 in rabbits. Levels of PAI-1 antigen in rabbit plasma were 9.8 ± 4.6 ng/ml (mean ± SD, n = 6), with a corresponding value of 20.5 ± 13.5 ng/ml for PAI-1 activity. In rabbit serum PAI-1 antigen was 11.8 ± 4.9 ng/ml (n = 6) and PAI-1 activity was 2.9 ± 2.0 ng/ml (n = 6). Endotoxin injection (20 μg/kg, iv) induced a time-dependent increase of both PAI-1 antigen and PAI-1 activity levels in rabbit plasma, eventually resulting in a 40- to 90-fold increase (p <0.0001 vs baseline). A linear correlation was found between PAI-1 antigen and activity levels in normal plasma (r = 0.90, n = 6, p <0.05) and in plasma from endotoxin-treated rabbits (r = 0.98, n = 20, p <0.001). Analysis of PAI-1 antigen and activity in lysates of washed rabbit platelets revealed the absence of PAI-1 (i.e. <0.03 ng/108 platelets).

In conclusion, development of specific immunological assays allowed the quantitation of PAI-1 in rabbit samples. In striking contrast to other species (human, rat, mouse, pig) rabbit platelets lack detectable amounts of PAI-1 (i.e. >100-1000 fold lower vs other species studied). This observation may have important implications for the use of experimental rabbit models especially in studies on the role of platelets in various pathological conditions including thrombosis and atherosclerosis.

Elucidation of the epitope of a latency-inducing antibody: identification of a new molecular target for PAI-1 inhibition

The monoclonal antibody MA-33B8, directed against the serpin plasminogen activator inhibitor-1 (PAI-1), has unique functional properties as it induces acceleration of the active-to-latent transition (Verhamme I et al. J Biol Chem 274: 17511-7, 1999), resulting in PAI-1 activity neutralization. In this study, we have identified Lys88, Asp89, Lys176 and His229 as the major residues of the conformational epitope. Lysine88 and aspartic acid89, contributing the most, are located on the loop between α-helix D and β-strand 2A. Strikingly, these residues undergo dramatic conformational changes during latency conversion. The three-dimensional localization of this epitope and its differential exposure in active and latent forms of PAI-1 provide a molecular explanation for the underlying mechanism of MA-33B8. Rearrangements of hydrogen bonds in this region upon latency transition, strongly suggest that binding of MA-33B8 may result in the generation of energy required in the rate-limiting step of latency transition. Thus, this novel epitope reveals a new interaction site in PAI-1 as a putative molecular target to modulate PAI-1 activity.

Importance of N-Terminal Residues in Plasminogen Activator Inhibitor 1 on its Antibody Induced Latency Transition

The serpin plasminogen activator inhibitor-1 (PAI-1) is a wellknown risk factor for thromboembolic and cardiovascular diseases. Many efforts have been made to reveal structure-function relationship in PAI-1, including the understanding of its unique latency transition. In this study, we describe the molecular characterization of PAI-1 neutralization by MA-159M12, a monoclonal antibody against rat PAI-1.

Time-dependent inactivation of PAI-1, exposure of a trypsin cleavage site typically for the latent conformation and disappearance of elastase susceptibility revealed that MA-159M12 accelerated the active to latent, conformational transition (t1/2 120 ± 12 min and 18 ± 3.6 min in the absence and presence of MA-159M12, p <0.0001).

Cross-reactivity analysis of the antibody with various rat/human PAI-1 chimeras revealed that the epitope resides in αhA of rat PAI-1. Subsequent alanine-scanning mutagenesis and binding studies demonstrated that Pro2- Leu3- Pro4-Glu5 constitute the major residues of the epitope for MA-159M12. In conclusion, these findings demonstrate that, even though unexpected based on current knowledge on PAI-1 stability and function, interference with αhA results in a destabilisation of its active, inhibitory conformation. Therefore, αhA forms a putative target for the rational development of PAI-1 neutralizing components.

Identification of a Functional Epitope in Plasminogen Activator Inhibitor-1, not Localized in the Reactive Center Loop

Plasminogen activator inhibitor-1 (PAI-1) is unique among the ser-pins because of its conformational flexibility. Previously, we have characterized monoclonal antibodies that neutralize PAI-1 activity by switching the active, inhibitory pathway into the non-inhibitory substrate pathway (10). Here, we report the identification of the epitopes for two of these antibodies, i.e. MA-55F4C12 and MA-33H1 and apply this information to explain their functional effects.

Using a random PAI-1 epitope library (11), phages displaying specific PAI-1 fragments were isolated after selective screening for binding onto the respective antibodies. Competition experiments with PAI-1 demonstrated that selected phages react with the antigen-binding site of the antibodies. Comparison of the sequences of the different overlapping inserts, encoding the PAI-1 epitope, with the PAI-1 cDNA sequence revealed that both epitopes, even though not identical, are located between amino acids Glu128 and Ala156 in the PAI-1 molecule. Analysis within the three-dimensional structure of PAI-1 showed that these residues completely cover helix F, which is localized close to the major β-sheet A. This localization provides a rational basis for explaining the mechanism of PAI-1 inactivation by both antibodies: upon binding of these antibodies to PAI-1, a stabilizing effect is induced on helix F resulting in a decrease of the kinetics of insertion of the reactive site loop into β-sheet A during interaction with the target proteinase. This forms the molecular basis for the observed functional effects of these antibodies and fully explains why PAI-1, in the presence of these antibodies, has lost its inhibitory properties but remains succeptible to cleavage by its target proteinases. The identification and localization of these functionally important epitopes opens new perspectives for the development of pharmacological agents with PAI-1 modulating properties.

Clearance of plasmin-PN-1 complexes by vascular smooth muscle cells in human aneurysm of the ascending aorta

Plasminogen is a circulating zymogen which enters the arterial wall by radial, transmural hydraulic conductance, where it is converted to plasmin by tissue plasminogen activator t-PA on an activation platform involving S100A4 on the vascular smooth muscle cell (vSMC) membrane. Plasmin is involved in the progression of human thoracic aneurysm of the ascending aorta (TAA). vSMCs protect the TAA wall from plasmin-induced proteolytic injury by expressing high levels of antiproteases. Protease nexin-1 (PN-1) is a tissue antiprotease belonging to the serpin superfamily, expressed in the vascular wall, and is able to form a covalent complex with plasmin. LDL receptor-related protein-1 (LRP-1) is a scavenger receptor implicated in protease-antiprotease complex internalization. In this study, we investigated whether PN-1 and LRP-1 are involved in the inhibition and clearance of plasminogen by the SMCs of human TAA. We demonstrated an overexpression of S100A4, PN-1, and LRP-1 in the medial layer of human TAA. Plasminogen activation taking place in the media of TAA was revealed by immunohistochemical staining and plasmin activity analyses. We showed by cell biology studies that plasmin-PN-1 complexes are internalized via LRP-1 in vSMCs from healthy and TAA media. Thus, two complementary mechanisms are involved in the protective role of PN-1 in human TAA: one involving plasmin inhibition and the other involving tissue clearance of plasmin-PN1 complexes via the scavenger receptor LRP-1.

The road from development to approval: evaluating the body of evidence to confirm biosimilarity

Biosimilars are products that contain a similar version of the active substance of an already authorized original biologic medicinal product (reference medicinal product). Their development requires special consideration, as similarity to the reference agent needs to be established through a comprehensive comparability exercise. Given the complex nature of these agents, minor structural differences may emerge, but the process of biosimilarity determination is designed to ascertain that the nature and impact of these differences are not clinically significant. Determination of biosimilarity should follow quality-by-design principles, which provide a deep understanding of the product development process, guided by pre-defined objectives, process control and risk management. Compared with novel biologic development, biosimilar development places greater emphasis on establishing preclinical quality characteristics. Determination of comparability of quality characteristics includes assessment of physicochemical properties, biological activity, immunochemical properties, purity, impurity and quantity, with appropriate in vivo pharmacology studies being conducted thereafter. Head-to-head comparisons are then conducted to determine pharmacokinetic and pharmacodynamic characteristics, and efficacy, safety and tolerability in phase I and phase III clinical studies. Post-approval risk management requirements include implementation of pharmacovigilance systems and risk management through, for example, the conduct of pharmacoepidemiological studies. There are several biosimilars used in the field of rheumatology that are available in the European Union, or in development, that offer the potential to increase affordability/accessibility of biological treatment. The role of these agents in rheumatology will be determined by the confidence placed in them by rheumatologists. These prescribers should expect high-quality data evaluated by an extensive assessment process.

The Market of Biopharmaceutical Medicines: A Snapshot of a Diverse Industrial Landscape

Background: Biopharmaceutical medicines represent a growing share of the global pharmaceutical market, and with many of these biopharmaceutical products facing loss of exclusivity rights, also biosimilars may now enter the biopharmaceutical market.

Objectives: This study aims to identify and document which investment and development strategies are adopted by industrial players in the global biopharmaceutical market.

Methods: A descriptive analysis was undertaken of the investment and development strategies of the top 25 pharmaceutical companies according to 2015 worldwide prescription drug sales. Strategies were documented by collecting data on manufacturing plans, development programs, acquisition and collaboration agreements, the portfolio and pipeline of biosimilar, originator and next-generation biopharmaceutical products. Data were extracted from publicly available sources.

Results: Various investment and development strategies can be identified in the global biopharmaceutical market: (a) development of originator biopharmaceuticals, (b) investment in biotechnology, (c) development of next-generation biopharmaceuticals, (d) development of biosimilars, (e) investment in emerging countries, and (f) collaboration between companies. In the top 25 pharmaceutical companies almost every company invests in originator biopharmaceuticals and in biotechnology in general, but only half of them develops next-generation biopharmaceuticals. Furthermore, only half of them invest in development of biosimilars. The companies' biosimilar pipeline is mainly focused on development of biosimilar monoclonal antibodies and to some extent on biosimilar insulins. A common strategy is collaboration between companies and investment in emerging countries.

Conclusions: A snapshot of investment and development strategies used by industrial players in the global biopharmaceutical market shows that all top 25 pharmaceutical companies are engaged in the biopharmaceutical market and that this industrial landscape is diverse. Companies do not focus on a single strategy, but are involved in multiple investment and development strategies. A common strategy to market biopharmaceuticals is collaboration between companies. These collaborations can as well be used to gain access in regions the company has less experience with. With patents expiring for some of the highest selling monoclonal antibodies, this snapshot highlights the interest of companies to invest in the development of these molecules and/or enter into collaborations to create access to these molecules.

The Language of Biosimilars: Clarification, Definitions, and Regulatory Aspects

Biologic therapies have revolutionized treatment of a number of diseases. Patents and exclusivity for a number of biologics are expiring. This has created the opportunity for the development and approval of biosimilars. Biosimilars are biologic products developed using a step-wise approach to result in a biologic that demonstrates no clinically meaningful differences in terms of quality attributes, efficacy, safety, and immunogenicity compared with an existing licensed, originator biologic. As more biosimilars receive regulatory approval and reach the market, it is increasingly important for healthcare providers to understand the terminology about biosimilars. To help support healthcare providers, the aim of this manuscript is to (i) support understanding of the language of biosimilars, (ii) review the regulatory and manufacturing processes employed in developing a biosimilar, and (iii) provide information for clinical decisions about the use of biosimilars. Because biologics are large, structurally complex proteins, biosimilars cannot be considered generic equivalents to the originator. Biosimilars are developed and evaluated using rigorous processes involving detailed analytical and functional studies, nonclinical assessments, and clinical trials. Clinical studies evaluating the potential biosimilar are designed differently than those for approval of a novel biologic since the aim is merely to confirm similar efficacy and safety and not to demonstrate clinical benefit per se. Extrapolation of data may be used to grant approval of biosimilars in indications not directly evaluated in clinical studies using the biosimilar.

Overcoming Barriers to the Market Access of Biosimilars in the European Union: The Case of Biosimilar Monoclonal Antibodies

BACKGROUND

In 2014, six of the top ten blockbuster medicines were monoclonal antibodies. This multibillion-dollar market with expiring patents is the main driver for the development of biosimilar mAbs. With the ever-increasing cost of healthcare and the economic pressure to reduce or sustain healthcare expenses, biosimilars could be instrumental in reducing costs for medication and increasing patient access to treatment.

OBJECTIVES

The aim of this study is to identify and describe the barriers to market access of biosimilar mAbs in the European Union and to analyze how these barriers could be overcome.

METHODS

A narrative literature review was carried out using the databases PubMed, Embase, and EconLit. Studies were published in English or Dutch. Additionally, the reference list of the articles was checked for relevant studies. Articles and conference papers known to the authors were included as well. Articles were also identified by searching on the website of the Generics and Biosimilars Initiative (GaBI) journal.

RESULTS

Six barriers were identified based on available literature: The manufacturing process, the regulatory process, intellectual property rights, lack of incentive, the impossibility of substitution, and the innovator's reach. These six barriers are presented as a possible framework to study the market access of biosimilar mAbs. Based on the literature search, recommendations can be made to overcome these barriers: (i) invest initially in advanced production processes with the help of single-use technology, experience or outsourcing (ii) gain experience with the regulatory process and establish alignment between stakeholders (iii) limit patent litigation, eliminate evergreening benefits, build out further the unitary patent and unified patent litigation system within the EU (iv) create demand-side policies, disseminate objective information (v) change attitude toward biosimilar switching/substitution, starting with physician, and patient education (vi) differentiate the biosimilar by service offerings, use an appropriate comparator in cost-effectiveness analyses.

CONCLUSIONS

Barriers to the market access of biosimilar mAbs could be reduced when more transparency and communication/education is used in all steps toward market access in order to increase the trust in biosimilar mAbs by all stakeholders. Only then biosimilar mAbs will be able to fully capture their cost saving potential.

Biosimilars - terms of use

The impending expiry of the patent on a number of leading biologic drugs has led to a surge in the development of 'biosimilar' or 'follow-on' products. However, in contrast to generic small-molecule medicines, biosimilars are not identical to their reference products. The differences and complexities surrounding both the molecular structure and the manufacturing process for biologics and biosimilars have resulted in a lack of clarity regarding the terms used in different parts of the world to define various aspects of development and utilization such as regulatory approval, pharmacovigilance, interchangeability and treatment-naivety. This makes quantitative evaluation of biosimilars a great challenge to both the scientific community and regulatory agencies. This manuscript attempts to clarify the terms used and address an important knowledge gap which is currently resulting in an increasing rush to position biosimilars for certain indications and patients in the absence of agreed upon definitions.