September 16, 2015

The adsorption of allergoids and 3-O-desacyl-4′-monophosphoryl lipid A (MPL®) to microcrystalline tyrosine (MCT) in formulations for use in allergy immunotherapy

Highlights

Vaccine potency is affected by antigen-adjuvant adsorption.
MATA-MPL immunotherapy formulations effectively treat IgE mitigated allergy.
Allergoids & MPL® are consistently adsorbed in MATA-MPL formulations.
Adsorption of MPL® to MCT could be influenced by C–H · · · ·π interactions.
MCT could be an alternative adjuvant depot for infectious disease antigens.

Abstract

Infectious disease vaccine potency is affected by antigen adjuvant adsorption. WHO and EMA guidelines recommend limits and experimental monitoring of adsorption in vaccines and allergy immunotherapies. Adsorbed allergoids and MPL® in MATA-MPL allergy immunotherapy formulations effectively treat IgE mitigated allergy. Understanding vaccine antigen adjuvant adsorption allows optimisation of potency and should be seen as good practice; however current understanding is seldom applied to allergy immunotherapies.

The allergoid and MPL® adsorption to MCT in MATA-MPL allergy immunotherapy formulations was experimental determination using specific allergen IgE allerginicity and MPL® content methods. Binding forces between MPL® and MCT were investigated by competition binding experiments.
MATA-MPL samples with different allergoids gave results within 100–104% of the theoretical 50 μg/mL MPL® content. Unmodified drug substance samples showed significant desirable IgE antigenicity, 1040–170 QAU/mL. MATA-MPL supernatant samples with different allergoids gave results of ≤ 2 μg/mL MPL® and ≤ 0.1–1.4 QAU/mL IgE antigenicity, demonstrating approximately ≥ 96 & 99% adsorption respectively. Allergoid and MPL® adsorption in different MATA-MPL allergy immunotherapy formulations is consistent and meets guideline recommendations. MCT formulations treated to disrupt electrostatic, hydrophobic and ligand exchange interactions, gave an MPL® content of ≤ 2 μg/mL in supernatant samples. MCT formulations treated to disrupt aromatic interactions, gave an MPL® content of 73–92 μg/mL in supernatant samples. MPL® adsorption to l-tyrosine in MCT formulations is based on interactions between the 2-deoxy-2-aminoglucose backbone on MPL® and aromatic ring of l-tyrosine in MCT, such as C–H⋯π interaction. MCT could be an alternative adjuvant depot for some infectious disease antigens.

Graphical abstract

The measured adsorption of MPL® to l-tyrosine in MATA-MPL allergy immunotherapy formulations, which has been shown to be disrupted by the addition of naphthalene a stronger aromatic centre, could depend significantly on C–H⋯π interactions between upward facing C–H's on the 2-deoxy-2-aminoglucose of MPL® and the aromatic ring onl-tyrosine.

Abbreviations

  • MPL®monophosphoryl lipid A
  • MCTmicrocrystalline tyrosine
  • WHOWorld Health Organisation
  • EMAEuropean Medicines Agency
  • MATAmodified allergen tyrosine adsorbed
  • C–H⋯πcarbon hydrogen delocalised aromatic electron interaction
  • IgE,immunoglobulin E
  • GCgas chromatography
  • Th2subset of innate allergen specific immune response
  • TLR4toll-like receptor four
  • IgGimmunoglobulin G
  • MD2:TLR4,myeloid differential protein 2:toll-like receptor four complex
  • C–Hcarbon hydrogen;
  • GMPgood manufacturing practice
  • WFIwater for injections
  • UKUnited Kingdom;
  • Ltdlimited
  • Ph. EurEuropean Pharmacopeia
  • RPMrevolutions per minute
  • RCF,relative centrifugal force
  • FIDflame ionisation detector
  • PSIpounds per square inch;
  • ELISAenzyme-linked immunosorbent assay
  • DPBSDulbecco's phosphate buffered saline
  • BSAbovine serum albumin
  • QAUquality assurance units
  • MPL-AF,monophosphoryl lipid A aqueous formulation
  • SDstandard deviation
  • %RSD,percentage relative standard deviation
  • πdelocalised aromatic electrons
  • Plcpublic limited company

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