Ultra-sub-stoichiometric “Dynamic” Bioconjugation Reduces Viscosity by Disrupting Immunoglobulin Oligomerization

Abstract

Monoclonal antibodies (mAb) are a major focus of the pharmaceutical industry, and polyclonal immunoglobulin G (IgG) therapy is used to treat a wide variety of health conditions. As some individuals require mAb/IgG therapy their entire life, there is currently a great desire to formulate antibodies for bolus injection rather than infusion. However, to achieve the required doses, very concentrated antibody solutions may be required. Unfortunately, mAb/IgG self-assembly at high concentration can produce an unacceptably high viscosity for injection. To address this challenge, this study expands the concept of "dynamic covalent chemistry" to "dynamic bioconjugation" in order to reduce viscosity by interfering with antibody−antibody interactions. Ultra-sub-stoichiometric amounts of dynamic PEGylation agents (down to the nanomolar) significantly reduced the viscosity of concentrated antibody solutions by interfering with oligomerization.

Poly(glutamic acid)-Based Viscosity Reducers for Concentrated Formulations of a Monoclonal IgG Antibody

“…All polymer additives among 45PLE, 90PLE, and 45PLEL-10PEG3 were capable of decreasing the viscosity of the mAb below the practical threshold of 50 mPa s. Of note, the addition of 45PLE-10PEG3 without NaCl (11 mM equiv glutamate units) also provided a fluidification near 50 mPa s, more effective than NaCl 55 mM with no polyglutamate. As PEGylated copolymers may in addition contribute to stability (in contrast to the use of NaCl, which can impair stability by enabling sticky collisions between mAbs and a faster irreversible aggregation rate), the trends observed suggest the interest of further studies of the aging and formulations using PLEs and/or PEGylated PLE derivatives. In this line, the use of buffers of low ionic strength (in term of simple salt concentration) has been documented to provide better long-term stability of highly concentrated solutions of mAbs .…”

“…But it is still challenging to predict the viscosity pattern of nonspherical, flexible proteins such as mAbs. The complexity of the viscosification mechanism of the mAb and specifically a high sensitivity to concentration are presumably due to contributions of mAb–mAb contact points − or the formation of transient interprotein clusters. , In other words, a pronounced viscosity increase is generally associated with the presence of attractive interactions between mAbs, as suggested by experimental investigations on the correlation between viscosity and interaction parameters − ) or indications on the formation of interprotein reversible complexes at high concentrations. ,− But discrepancies with this simple rule are also reported …”

“…These small molecules typically provide weak and labile perturbations of the interactions, either by affecting the ionic strength or by screening specific patches onto mAbs. In situ PEGylation of IgGs has similarly been reported to improve fluidity . In other words, protein–protein attractions may be discouraged by using transient (dynamic) competitive binding with additives.…”

“…In situ PEGylation of IgGs has similarly been reported to improve fluidity. 19 In other words, protein−protein attractions may be discouraged by using transient (dynamic) competitive binding with additives. In particular, charged amino acids reduce viscosity, which can be tentatively explained by their ability to shield Coulombic interactions and to disrupt mAb−mAb associations.…”