Fcγ Receptor Dependency of Agonistic CD40 Antibody in Lymphoma Therapy Can Be Overcome through Antibody Multimerization

Abstract

Immunomodulatory mAbs, led by the anti-CTLA4 mAb ipilimumab, are an exciting new class of drugs capable of promoting anticancer immunity and providing durable control of some tumors. Close analysis of a number of agents has revealed a critical yet variable role for Fcγ receptors in their efficacy. In this article, we reveal that agonistic anti-CD40 mAbs have an absolute requirement for cross-linking by inhibitory FcγRIIB when used systemically to treat established BCL1 syngeneic lymphoma, and therapy is lost when using a mouse IgG2a mAb not cross-linked by FcγRIIB. Furthermore, in FcγRIIB-deficient mice the lymphoma itself can provide FcγRIIB to cross-link anti-CD40 on neighboring cells, and only when this is blocked does therapy fail. The dependence on FcγRIIB for immunostimulatory activity was not absolute, however, because when anti-CD40 mAbs were administered systemically with the TLR3 agonist polyinosinic:polycytidylic acid or were given subcutaneously, activatory FcγR could also provide cross-linking. Using this mechanistic insight, we designed multimeric forms of anti-CD40 mAb with intrinsic FcγR-independent activity that were highly effective in the treatment of lymphoma-bearing mice. In conclusion, FcγR-independent anti-CD40 activation is a viable strategy in vivo. These findings have important translational implications, as humans, unlike mice, do not have IgG that binds strongly to FcγRIIB; therefore FcγR-independent derivatives represent an attractive therapeutic option.

Dual Roles for Regulatory T-cell Depletion and Costimulatory Signaling in Agonistic GITR Targeting for Tumor Immunotherapy

“…S3). This suggested that the agonist signaling capacity of these two antibodies is equivalent and is not dependent on FcgR binding, unlike anti-CD40 antibodies that require FcgR binding for their agonist activity (20). When administered in vivo, N297A-mutant mDTA-1 showed similar binding characteristics on intratumoral T cells and had equivalent pharmacokinetics properties as non-mutant mDTA-1 ( Supplementary Fig.…”

Upregulation of FcγRIIb on monocytes is necessary to promote the superagonist activity of TGN1412

“…21 Work with CD40 has shown that simply cross-linking the receptors is sufficient for activity and that no downstream signaling is required. 20,23,30 Whether the same holds true for TGN1412 and CD28 remains to be confirmed.…”

Development and Characterization of Monoclonal Antibodies Specific for Mouse and Human Fcγ Receptors

“…For example, whereas the optimal immunestimulating, antitumor isotype for anti-CD40 mAb when injected i.v. is an mIgG1, due to its ability to bind avidly to mFcgRII and cross-link the associated CD40 molecules, a normally inert mIgG2a isotype is found to gain appreciable activity when introduced s.c., and this activity is dependent upon binding activatory mFcgR (13,15). Principally, this property is influenced by which FcgR are expressed in a given location and their affinity for a particular mAb isotype, but certainly comprehensive knowledge of FcgR expression patterns in each location will help in the finetuning and design of mAb reagents requiring FcgR engagement for specific functions.…”

“…As FDC are also a source of captured Ag, they may represent an ideal cell type for augmenting further Ag presentation and processing for subsequent T cell stimulation. This observation may therefore relate to the potent immune stimulating activity of mAb targeting TNF receptor super family members such as CD40 and DR4/5 (12)(13)(14)50). In contrast to direct targeting mAb such as rituximab, which are impaired by mFcgRII and hFcgRIIB, these receptors are now known to be an important component of immunomodulatory mAb activity, where they serve to further cross-link the target receptor for optimal signaling (20)(21)(22)(23)(24)(25)reviewed in Ref.…”

“…Although a large body of data indicated that all mAb would become more effective with stronger engagement of activatory relative to inhibitory FcgR, this paradigm has recently been challenged (12)(13)(14)reviewed in Ref. 15).…”