Sustained systemic delivery of monoclonal antibodies by genetically modified skin fibroblasts

Biosimilar Gene Therapy: Investigational Assessment of Secukinumab Gene Therapy

Objective

Tumor necrosis factor-alpha (TNF-α), checkpoint inhibitors, and interleukin-17 (IL-17) are critical targets in inflammation and autoimmune diseases. Monoclonal antibodies (mAbs) have a successful portfolio in the treatment of chronic diseases. With the current progress in stem cells and gene therapy technologies, there is the promise of replacing costly mAbs production in bioreactors with a more direct and cost-effective production method inside the patient’s cells. In this paper we examine the results of an investigational assessment of secukinumab gene therapy.

Materials and Methods

In this experimental study, the DNA sequence of the heavy and light chains of secukinumab antibodies were cloned in a lentiviral vector. Human chorionic villous mesenchymal stem cells (CMSCs) were isolated and characterized. After lentiviral packaging and titration, part of the recombinant viruses was used for transduction of the CMSCs and the other part were applied for systemic gene therapy. The engineered stem cells and recombinant viruses were applied for ex vivo and in vivo gene therapy, respectively, in different groups of rat models. In vitro and in vivo secukinumab expression was confirmed with quantitative real-time polymerase chain reaction (qRT-PCR), western blot, and ELISA by considering the approved secukinumab as the standard reference.

Results

Cell differentiation assays and flow cytometry of standard biomarkers confirmed the multipotency of the CMSCs. Western blot and qRT-PCR confirmed in vitro gene expression of secukinumab at both the mRNA and protein level. ELISA testing of serum from treated rat models confirmed mAb overexpression for both in vivo and ex vivo gene therapies.

Conclusion

In this study, a lentiviral-mediated ex vivo and in vivo gene therapy was developed to provide a moderate dose of secukinumab in rat models. Biosimilar gene therapy is an attractive approach for the treatment of autoimmune disorders, cancers and other chronic diseases.

In situ production of therapeutic monoclonal antibodies

The use of antibodies as a treatment for disease has it origins in experiments performed in the 1890s, and since these initial experiments, monoclonal antibodies (mAbs) have become one of the fastest growing therapeutic classes for the treatment of cancer, autoimmune disease, and infectious diseases. However, treatment with therapeutic mAbs often requires high doses given via long infusions or multiple injections, which, coupled with the prohibitively high cost associated with the production of clinical-grade proteins and the transient serum half-lives that necessitate multiple administrations to gain therapeutic benefits, makes large-scale treatment of patients, especially patients in the developing world, difficult. Due to their low-cost and rapid scalability, nucleic acid-based approaches to deliver antibody gene sequences for in situ mAb production have gained substantial traction. In this review, we discuss new approaches to produce therapeutic mAbs in situ to overcome the need for the passive infusion of purified protein.

Immortalized cell lines for real-time analysis of circadian pacemaker and peripheral oscillator properties

In the mammalian circadian system, cell-autonomous clocks in the suprachiasmatic nuclei (SCN) are distinguished from those in other brain regions and peripheral tissues by the capacity to generate coordinated rhythms and drive oscillations in other cells. To further establish in vitro models for distinguishing the functional properties of SCN and peripheral oscillators, we developed immortalized cell lines derived from fibroblasts and the SCN anlage of mPer2 (Luc) knockin mice. Circadian rhythms in luminescence driven by the mPER2::LUC fusion protein were observed in cultures of mPer2 (Luc) SCN cells and in serum-shocked or SCN2.2-co-cultured mPer2 (Luc) fibroblasts. SCN mPer2 (Luc) cells generated self-sustained circadian oscillations that persisted for at least four cycles with periodicities of ≈24 h. Immortalized fibroblasts only showed circadian rhythms of mPER2::LUC expression in response to serum shock or when co-cultured with SCN2.2 cells. Circadian oscillations of luminescence in mPer2 (Luc) fibroblasts decayed after 3-4 cycles in serum-shocked cultures but robustly persisted for 6-7 cycles in the presence of SCN2.2 cells. In the co-culture model, the circadian behavior of mPer2 (Luc) fibroblasts was dependent on the integrity of the molecular clockworks in co-cultured SCN cells as persistent rhythmicity was not observed in the presence of immortalized SCN cells derived from mice with targeted disruption of Per1 and Per2 (Per1(ldc) /Per2 (ldc) ). Because immortalized mPer2 (Luc) SCN cells and fibroblasts retain their indigenous circadian properties, these in vitro models will be valuable for real-time comparisons of clock gene rhythms in SCN and peripheral oscillators and identifying the diffusible signals that mediate the distinctive pacemaking function of the SCN.

Sustained in vivo inhibition of protein domains using single-chain Fv recombinant antibodies and its application to dissect RGMa activity on axonal outgrowth

Antibodies are powerful tools for delineating the specific function of protein domains, yet several limitations restrict their in vivo applicability. Here we present a new method to obtain sustained in vivo inhibition of specific protein domains using recombinant antibodies. We show that long term in vivo expression of single-chain Fv (scFv) fragments in the developing CNS can be achieved through retroviral transduction. Moreover, specific scFvs generated against the N- and C-terminal domains of the repulsive guidance molecule, RGMa, prevent proper axon targeting in the visual system. This work reveals a previously unappreciated role for the RGMa N-terminal domain in axon guidance, and provides a novel, broadly applicable and rapid procedure to functionally antagonize any protein domain in vivo.

Stable antibody expression at therapeutic levels using the 2A peptide

Therapeutic monoclonal antibodies (mAbs) are currently being developed for the treatment of cancer and other diseases. Despite clinical success, widespread application of mAb therapies may be limited by manufacturing capabilities. In this paper, we describe a mAb delivery system that allows continuous production of a full-length antibody at high-concentrations in vivo after gene transfer. The mAb is expressed from a single open reading frame by linking the heavy and light chains with a 2A self-processing peptide derived from the foot-and-mouth disease virus. Using this expression system, we generated a recombinant adeno-associated virus vector encoding the VEGFR2-neutralizing mAb DC101 (rAAV8-DC101). A single dose of rAAV8-DC101 resulted in long-term expression of >1,000 microg/ml of DC101 in mice, demonstrating significant anti-tumor efficacy. This report describes the first feasible gene therapy approach for stable delivery of mAbs at therapeutic levels, which may serve as an attractive alternative to direct injection of mAbs.

Regulatable systemic production of monoclonal antibodies by in vivo muscle electroporation

The clinical application of monoclonal antibodies (mAbs) potentially concerns a wide range of diseases including, among others, viral infections, cancer and autoimmune diseases. Although intravenous infusion appears to be the simplest and most obvious mode of administration, it is very often not applicable to long-term treatments because of the restrictive cost of mAbs certified for human use and the side effects associated with injection of massive doses of antibodies. Gene/cell therapies designed for sustained and, possibly, regulatable in vivo production and systemic delivery of mAbs might permit to advantageously replace it. We have already shown that several such approaches allow month- to year-long ectopic antibody production by non-B cells in living organisms. Those include grafting of ex vivo genetically modified cells of various types, in vivo adenoviral gene transfer and implantation of encapsulated antibody-producing cells. Because intramuscular electrotransfer of naked DNA has already been used for in vivo production of a variety of proteins, we have wanted to test whether it could be adapted to that of ectopic mAbs as well. We report here that this is actually the case since both long-term and regulatable production of an ectopic mAb could be obtained in the mouse taken as a model animal. Although serum antibody concentrations obtained were relatively low, these data are encouraging in the perspective of future therapeutical applications of this technology in mAb-based immunotherapies, especially in developing countries where cost-effective and easily implementable technologies would be required for large-scale applications in the context of severe chronic viral diseases such as HIV and HCV infections.

Monoclonal Antibodies Produced by Muscle after Plasmid Injection and Electroporation

Antibodies are useful for the treatment of a variety of diseases. We here demonstrate that mouse muscle produced monoclonal antibodies (mAb) after a single injection of immunoglobulin genes as plasmid DNA. In vivo electroporation of muscle greatly enhanced antibody production. For chimeric antibodies, levels of 50-200 ng mAb/ml serum were obtained but levels declined after 7-14 days due to an immune response against the xenogeneic parts of the antibody. By contrast, fully mouse antibodies persisted in serum for at least 7 months. mAb produced by the muscle had correct structure, specificity, and biological effector functions. The findings were extended to a larger animal, the sheep, in which mAb serum levels of 30-50 ng/ml were obtained. Sustained levels of serum mAb, induced by single injection of Ig genes and electroporation of muscle cells, may offer significant advantages in the treatment of human diseases.

Monoclonal antibody 667 recognizes the variable region A motif of the ecotropic retrovirus CasBrE envelope glycoprotein and inhibits Env binding to the viral receptor

Monoclonal antibody (MAb) 667 is a neutralizing mouse monoclonal antibody recognizing the envelope glycoprotein (Env) of the ecotropic neurotropic murine retrovirus CasBrE but not that of other murine retroviruses. Since 667 can be used for preclinical studies of antiviral gene therapy as well as for studying the early events of retroviral infection, we have cloned its cDNAs and molecularly characterized it in detail. Spot technique-based experiments showed that 667 recognizes a linear epitope of 12 amino acids located in the variable region A of the receptor binding domain. Alanine scanning experiments showed that six amino acids within the epitope are critical for MAb binding. One of them, D(57), is not present in any other murine retroviral Env, which suggests a critical role for this residue in the selectivity of 667. MAb 667 heavy- and light-chain cDNAs were functionally characterized by transient transfection into Cos-7 cells. Enzyme-linked immunosorbent assays and Biacore studies showed that the specificities as well as the antigen-binding thermodynamic and kinetic properties of the recombinant 667 MAb (r667) produced by Cos-7 cells and those of the parental hybridoma-produced MAb (h667) were similar. However, h667 was shown to contain contaminating retroviral and/or retrovirus-like particles which interfere with both viral binding and neutralization experiments. These contaminants could successfully be removed by a stringent purification protocol. Importantly, this purified 667 could completely prevent retrovirus binding to target cells and was as efficient as the r667 MAb produced by transfected Cos-7 cells in neutralization assays. In conclusion, this study shows that the primary mechanism of virus neutralization by MAb 667 is the blocking of the retroviral receptor binding domain of CasBrE Env. In addition, the findings of this study constitute a warning against the direct use of hybridoma cell culture supernatants for studying the initial events of retroviral cell infection as well as for carrying out in vivo neutralization experiments and suggest that either recombinant antibodies or highly purified antibodies are preferable for these purposes.

High in vivo production of a model monoclonal antibody on adenoviral gene transfer

The therapeutic potential of monoclonal antibodies (MAbs) for treating a variety of severe or life-threatening diseases is high. Although intravenous infusion appears to be the simplest and most obvious mode of administration, it is not applicable in many long-term treatments. It might, however, be advantageously replaced by gene/cell therapies, rendering treatments cost-effective and eliminating the short- and long-term side effects associated with injection of massive doses of antibodies. Grafting of ex vivo genetically modified cells of various types has already been used for in vivo production and systemic delivery of MAbs in mice. However, although sustained for long periods of time, serum levels of ectopic MAbs were low. We show here that in vivo administration to mice of a first-generation adenoviral vector expressing a model MAb also permits achievement of the same goal, but with 100 to 200 times better efficiency that in any other case of gene transfer described thus far. We also investigated for possible anti-idiotypic response against the ectopic MAb. None was detected in the animals expressing the lowest levels of ectopic MAb production; a response was detected among the highest producers. In the latter case, however, the response was low and could not exert any significant neutralizing activity. In conclusion, our work indicates that high levels of circulating ectopic MAb can be obtained on direct in vivo gene transfer without inducing an anti-idiotypic response sufficiently robust to exert a neutralizing effect. This observation is encouraging in the perspective of clinical applications of this technology.

Skin as a potential organ for ectopic monoclonal antibody production

The therapeutic potential of monoclonal antibodies for treating a variety of severe or life-threatening diseases is high. Although intravenous infusion appears the simplest and most obvious mode of administration, it is not applicable to many long-term treatments. It might be advantageously replaced by gene/cell therapies, however, rendering treatments cost-effective and eliminating the short- and long-term side-effects associated with injection of massive doses of antibodies. We have tested whether skin can potentially be used as an organ for production and systemic delivery of ectopic antibodies. Normal human primary keratinocytes were shown to be capable of synthesis and secretion of a model monoclonal antibody directed against human thyroglobulin upon retroviral gene transduction in vitro. Neo- epidermis reconstructed in vitro, either in cell culture inserts or on dermal substrates, from such modified keratinocytes also produced the monoclonal antibody. Interestingly, the latter could cross the epidermis basal layer and be released in culture fluids. Finally, grafting of epidermis reconstituted in vitro on dermal substrates to SCID mice permitted sustained monoclonal antibody delivery into the bloodstream to be achieved. Our data thus show that genetically engineered keratinocytes can potentially be used for genetic antibody-based immunotherapies. They also indicate that proteins as big as 150 kDa, after release by engineered keratinocytes into skin intercellular spaces, can migrate to the general circulation, which is potentially important for a number of other gene-based therapies.

Tissue-engineered skin substitutes

The last two years have seen new tissue-engineered skin substitutes come onto the market and begin to resolve the various roles to which each is best suited. It is becoming evident that some of the very expensive cell-based products have cost-benefit advantage despite their high price and are valuable within the restricted applications for which they are intended. The use of skin substitutes for testing purposes has extended from epidermal keratinocytes to other integumentary epithelia and into preparations containing multiple cell types in which reactions resulting from paracrine interactions can be examined. Challenges remain in the application of gene therapy techniques to skin substitutes, both the control of transgene expression and in the selection of suitable genes to transfect. A coming challenge is the production of tissue-engineered products without the use of animal products other than human cells. A challenge that may be diminishing is the importance of acute rejection of allogeneic tissue-engineered skin substitutes.