Engineering pan–HIV-1 neutralization potency through multispecific antibody avidity

Abstract

Deep mining of B cell repertoires of HIV-1–infected individuals has resulted in the isolation of dozens of HIV-1 broadly neutralizing antibodies (bNAbs). Yet, it remains uncertain whether any such bNAbs alone are sufficiently broad and potent to deploy therapeutically. Here, we engineered HIV-1 bNAbs for their combination on a single multispecific and avid molecule via direct genetic fusion of their Fab fragments to the human apoferritin light chain. The resulting molecule demonstrated a remarkable median IC50 value of 0.0009 µg/mL and 100% neutralization coverage of a broad HIV-1 pseudovirus panel (118 isolates) at a 4 µg/mL cutoff—a 32-fold enhancement in viral neutralization potency compared to a mixture of the corresponding HIV-1 bNAbs. Importantly, Fc incorporation on the molecule and engineering to modulate Fc receptor binding resulted in IgG-like bioavailability in vivo. This robust plug-and-play antibody design is relevant against indications where multispecificity and avidity are leveraged simultaneously to mediate optimal biological activity.

Antibody avidity and multi-specificity combined to confer protection against SARS-CoV-2 and resilience against viral escape

“…We have previously reported the generation of tri-specific MB molecules using an engineered apoferritin split design (Fig. 1A) 38, 39 , whereby the human apoferritin protomer was split into two halves based on its four-helical bundle fold: the two N-terminal α helices (N-Ferr) and the two C-terminal α helices (C-Ferr). The genetic fusion and transfection into mammalian cell expression systems of a single chain (sc) Fab or a scFc at the N terminus of each apoferritin half and full apoferritin resulted in the secretion of self-assembled, oligomeric molecules capable of ultrapotent neutralization.…”

“…We have previously shown that the MB format is capable of triggering ADCP in vitro, indicating that the format in itself does not preclude incorporating effector function into the molecule 39 .…”

“…In addition, strategies to propel the potency of such mAbs have the potential to reduce the therapeutic dose and enable more practical routes of administration, which could reduce manufacturing costs and enable global availability. We have previously described a Multabody platform capable of delivering highly potent and broadly-acting molecules in vitro 38, 39 . Indeed, two years after the identification of the tri-specific 298-52-80 MB, derived from three mAbs of modest potency, to our knowledge, no mAb that surpasses the in vitro neutralization potency of this molecule against WT SARS-CoV-2 (IC 50 of 0.0002 µg/mL) has yet been described.…”

“…Following a similar principle, but using the human light-chain apoferritin protomer to drive oligomerization of antibody fragments, we developed a platform called the Multabody (MB) to increase neutralization potency of antibodies targeting SARS-CoV-2 38 and HIV-1 39 . Using this platform, enhanced affinity can be coupled with multi-specificity -the inclusion of several antibody fragments recognizing different epitopes -to result in antigen recognition that is more resistant to viral mutations 38,39 . This is particularly relevant in light of immune pressure driving the continued emergence of new variants of SARS-CoV-2, including those against which existing vaccines and drugs are less efficacious [40][41][42] .…”

“…Additionally, the avid molecules GEN3009 35 , INBRX-106(Inhibrx) 36 and IGM-8444 37 are being tested in Phase I/II clinical trials for the treatment of hematological and solid tumors, highlighting the clinical benefit of multivalent antibody-presenting formats. Following a similar principle, but using the human light-chain apoferritin protomer to drive oligomerization of antibody fragments, we developed a platform called the Multabody (MB) to increase neutralization potency of antibodies targeting SARS-CoV-2 38 and HIV-1 39 . Using this platform, enhanced affinity can be coupled with multi-specificity – the inclusion of several antibody fragments recognizing different epitopes – to result in antigen recognition that is more resistant to viral mutations 38, 39 .…”