Insights into the IgG heavy chain engineering patent landscape as applied to IgG4 antibody development.

Despite being the least abundant immunoglobulin G in human plasma, IgG4 are used therapeutically when weak effector functions are needed. The increase in engineered IgG4-based antibodies on the market led us to study the patent landscape of IgG4 Fc engineering, i.e., patents claiming modifications in the heavy chain. Thirty-seven relevant patent families were identified, comprising hundreds of IgG4 Fc variants focusing on removal of residual effector functions (since IgG4s bind to FcγRI and weakly to other FcγRs), half-life enhancement and IgG4 stability. Given the number of expired or soon to expire major patents in those 3 areas, companies developing blocking antibodies now have, or will in the near future, access to free tools to design silenced, half-life extended and stable IgG4 antibodies.

New structural formats of therapeutic antibodies for rheumatology.

Pharmaceutical companies strive continuously to develop better medications in order to remain competitive. In the arena of monoclonal antibodies and related biologics (fusion proteins containing an IgG Fc fragment), the thrust is not only toward identifying new targets, but also toward developing new molecular formats. Here, new-generation antibodies used to treat rheumatic diseases are discussed, with emphasis on relations linking structure to pharmacological effects and on the improvements expected from the new formats. Isotypic and allotypic antibody diversity has pharmacological implications and is already exploited in commercially available antibodies. Efforts to engineer the Fc fragment of the various immunoglobulin G subclasses are reviewed with reference to abatacept, ixekizumab, other mutated IgG4 antibodies currently in development, sapelizumab, anifrolumab, and tanezumab. Bispecific antibodies are a focus of increasing interest (particularly those binding to both IL-17 and TNFα) and may earn a place in the therapeutic armamentarium as a means of avoiding the use of antibody combinations. However, the construction and production of bispecific antibodies continues to raise major technological challenges. Other molecular formats involve the fusion of antibodies to cytokines or the use of nanobodies and peptibodies. These new formats are at the very early stages of development, and their clinical relevance remains unclear.

Rethinking the INN system for therapeutic antibodies.

In the context of a possible revision of the International Nonproprietary Names (INN) system of recombinant monoclonal antibodies, which is saturated, we propose several avenues of reflection driven by the primary goal of the INN, information of health-care professionals. Clinical considerations argue for an abandon of the substems A (target category) and B (origin category), which lengthen the INN without real added-value. On the contrary, new substems or suffixes are required to alert on the absence/presence of an Fc portion and/or multispecificity, which are essential from a pharmacological point of view. Moreover, we think it necessary to explicitly mention Fc variations since they could influence the pharmacology of these biopharmaceuticals, and hence their efficacy and side-effects. Besides indicating the subclass/isotype in the documents easily accessible to health care professionals, we propose to systematically describe both the natural variations (allotypes) by using the Gm (G marker) system, and the artificial variations by using a Ge (G engineering) system that is discussed here and could apply to all IgG constant domains (tentatively called the Fy portion).