Looking to a future of multiplex cell engineering

Cell & Gene Therapy Insights 2023; 9(11), 1523–1528

DOI: 10.18609/cgti.2023.199

Published: 11 January
Marco Alessandrini

‘Multiplexing’ has been one of the most prominent buzzwords of 2023 in the advanced therapies space. David McCall, Senior Editor, Cell & Gene Therapy Insights, speaks to Marco Alessandrini, CEO, Antion Biosciences about recent progress with and future targets for tunable multiplex cell engineering platforms.

As 2023 draws to a close, how would you sum up the year for cell and gene therapy?

MA: Without question, the field has been maturing exceptionally over the last year, with more approvals coming through. The challenges related to novel technologies are becoming clearer, and although there might be some ambiguity around the safety and efficacy of these newer approaches, there is a lot of excitement in the field as we anticipate more patients being cured of diseases that could not be treated otherwise.

Editing technologies, including base, prime, and epigenetic editing, are all evolving in impressive ways. There is a high degree of interest in the space, perhaps increasingly in in vivo gene therapy rather than ex vivo modified cell therapy solutions. Although there are challenges across the board, there will be wonderful options for patients down the line.

Arguably, cell and gene therapy is currently not living up to its full promise, but with the dedication that we see right now from developers in both the academic and private sectors, there is a tremendous driving force and scope for the application of these therapies. I see no reason why the promise of gene therapy will not be realized with time. For me, both cell therapy and gene therapy are here to stay. I am happy to see that Antion’s technology can compete in that space, existing not only as a mere add-on to the field, but also as a potential disruptor to the industry. We feel committed to this journey to see it happen.

Can you tell us more about Antion—it’s approach, platform, and R&D pipeline—and the progress you have made in 2023?

MA: Antion Biosciences is a spin-off from the University of Geneva. We officially spun out with investment from angel investors in 2019 and then managed to secure a partnership with Allogene Therapeutics. They are invested strategically in the company, with Antion also developing novel gene constructs for Allogene’s next generation of allogeneic CAR-T cell products. As a platform technology company that recently stepped out of a university, it has been powerful for us to have such pioneers already looking into the use of our technology. Soon afterwards, we also struck a very exciting collaboration with the Centre for Cellular Immunotherapies at the University of Pennsylvania.

Our technology centers on the ability to multiplex engineer in a modular and tunable fashion. We believe that making cell and gene therapy treatments widely accessible, safer, and more efficacious is primarily an engineering challenge that can only be overcome with high-end technologies that are inherently flexible by design. Our technology has the ability to add genes like a CAR or additional molecules, whilst at the same time—and in the same gene construct—decreasing the expression of others. In other words, both an additive and a subtractive effect, or even multiple additions or subtractions, can be achieved from a single gene construct (Figure 1Future CAR-T cell developments require the modulation of multiple genes to achieve prerequisite safety standards and optimize treatment efficacy. The challenge of cell and gene engineering strategies is thus to accommodate contrasting modalities—on the one hand, multi-gene addition to over-express molecules, and on the other to silence the expression of multiple genes (subtractive effect). CAR: chimeric antigen receptor; TCR: T cell receptor; HLA: human leukocyte antigen.Next generation CAR T-cell with multiplex gene modulation. Future CAR-T cell developments require the modulation of multiple genes to achieve prerequisite safety standards and optimize treatment efficacy. The challenge of cell and gene engineering strategies is thus to accommodate contrasting modalities—on the one hand, multi-gene addition to over-express molecules, and on the other to silence the expression of multiple genes (subtractive effect). CAR: chimeric antigen receptor; TCR: T cell receptor; HLA: human leukocyte antigen.).

All of the approved therapies on the market are CAR-only therapies engineered with only the CAR molecule. Our technology is a simple bolt-on to this in order to deliver the multiplex capability, not having to alter in any way the manufacturing process. Other approaches generally require the use of two technologies to first add the CAR, and then in a secondary step, to edit out key molecules for the multiplex effect. From a safety point of view, the way we deliver multiplex gene constructs is surprisingly simple and the efficiency of being able to modify many molecules at the same time is very promising. We recently presented work showing we can functionally silence the expression of six genes, in addition to co-expressing two genes at the same time—a CAR and a safety switch. It is a modular approach and by adding different components, we can dial up or dial down the expression of relevant molecules.

The tunability is another advantage. Certain molecules, such as human leukocyte antigen (HLA)-I, benefit from the tuning down of expression. The tuned-down effect might be more efficient than a complete knockout of HLA-I expression when it comes to host rejection of allogeneic cell therapies. With the exception of epigenetic editing technologies, no other editing technology can achieve similar. While HLA-I knockout very efficiently protects allogeneic cells from rejection by host T cells, it renders the cells prone to rampant rejection by host natural killer cells. It is therefore an absolute necessity to co-express natural killer inhibitory receptors, such as non-classical HLA-I fusion proteins. While this offers adequate protection, it comes with greater engineering complexity and an increasing genetic payload that compromises gene delivery and manufacturing efficiencies.

From a pipeline point of view, we are now looking to fulfill an unmet need on the clinical side. We have carefully selected our lead indication, which is a T cell malignancy. CD19 CARs are working efficiently for B-cell leukemias and lymphomas and B-cell maturation antigen CARs are working well for myeloma, but the most aggressive forms of leukemia and lymphoma are of T cell origin. It is a small subset of patients but given the current dearth of available treatments, we think CAR-T could be the most efficient way to treat these patients.

From a development point of view, we believe multiplex engineering is essential in this context, and therefore our technology also addresses an unmet engineering need where other technologies suffer poor yields and safety concerns. Antion technology allows the adding of a CAR and a safety switch molecule, in addition to silencing numerous receptors for added therapeutic benefit. We target a molecule called cluster of differentiation 7 (CD7), present on all T cells, which is highly expressed in leukemia and lymphoma patients of T cell origin. Firstly, we silence the expression of CD7 on the T cells and have good data to show that this is essential to prevent fratricide, rendering a higher product yield and healthier CAR-T cell populations. Since there are obvious issues in harvesting malignant T cells from a patient for autologous administration, it is preferable to pursue an allogeneic off-the-shelf product derived from healthy donors. Therefore, secondly, we need to silence the expression of T cell receptor to facilitate allogeneic treatment. But we also want to make these cells persistent and in the context of malignant T cell populations, greater rejection of the product may be seen as the T cells are present. So, thirdly, we also look to silence HLA molecules as a means of improving the persistence of these cells. Most notably, we are addressing these three arms from a single gene construct.

Can you expand on the benefits that multiplex cell engineering approaches bring to the field as a whole?

MA: Being able to multiplex engineer cells and tune them to increase efficiency is the future of engineered cell therapies. The CAR-only therapies are good, but they could be more efficient. If we want to break into a larger space in the industry, we need to address solid tumors. Current treatments are only for hematological malignancies, which covers only about 10% of the total cancer patient population.

We also want to make these treatments off-the-shelf and widely accessible globally, which is an important engineering challenge. Our multiplex approach is efficient in terms of adding and subtracting gene expression in a single construct. We can take the way that the current CAR-Ts are produced and manufactured and simply add our technology to deliver these additional benefits—it is an elegant solution and obviates the need to alter the already well-established gene delivery methods in any way whatsoever.

Modularity in multiplexing is certainly beneficial. As soon as we define a module that works well to silence a molecule, we can add it, remove it, or tune down the expression in our gene constructs. We can create a window of silencing—for example, of 50%, 75%, or even 95% silencing. We have recently shown that functional silencing can be achieved across the entire range. This extra level of tunability, as opposed to basic ‘on/off’ silencing (knockout), can be beneficial for certain targets.

What are the key considerations and challenges for Antion as you prepare to translate into first-in-human trials?

MA: A key challenge is expanding our internal expertise and understanding of what it takes to translate an R&D program into a clinical program. Fortunately, there are many seasoned professionals out there who can support us with this. The key remaining challenges are mainly from a CMC and process development point of view. Upscaling the production of our CAR-Ts is the most significant challenge for us. A natural expansion of the team is required to ensure our CMC and process development is fluent as we interact with regulators. We are preparing for this extensively.

As you look ahead to 2024 and beyond, what will be some important next steps in technology evolution and application to look out for in the engineered cell therapy field?

MA: We are watching technologies mature, including our own, and many are showing exceptional efficiencies. These technologies are powerful in terms of what they can achieve, but the key now is translating them into products.

The editing space will continue to evolve, with gene editing becoming more efficient, along with novel technologies starting to feature more prominently, including base editing, prime editing, and excitingly, epigenetic editing. These are all different tools in the toolbox to help address unmet needs. Certain indications will be best addressed with certain technologies or combinations of technologies. Our technology is one piece of the puzzle, and we are excited to see how it can be applied, whether it be standalone or in combination with any of the editing technologies mentioned above.

The field also needs to consider improving the safety assessment of these technologies. These are all highly novel technologies, so we must ensure we can concretely assess the safety of the products derived from them in their engineering and delivery. Genotoxicity due to genomic re-arrangements and instability can have serious detrimental effects on the industry, which is something we most certainly need to avoid at all costs.

Can you sum up one or two key goals and priorities that you have for Antion over the course of 2024 and beyond?

MA: At Antion Biosciences, our main goal is to nail down our technology platform validation. We have already shown the ability to silence multiple molecules efficiently—validation involves creating the allogeneic off-the-shelf versions from an engineered T cell point of view. We are now comfortable in saying that our technology can be used to create allogeneic CAR-T cells with exceptional efficiency.

Another element is to improve their persistence, as I mentioned earlier. This involves preventing rejection, which can be done by downregulating both HLA-I and HLA-II molecules. I hope that in 2024, we will definitively nail down the anti-rejection capability of our technologies and engineer cells that are simultaneously 1) non-alloreactive for off-the-shelf administration, and 2) hypoimmunogenic for improved persistence by preventing rejection from the host immune system. Then, we can address the next most significant key area—improving cellular potency. There is a general drive towards improving the potency (or efficiency) of both autologous and allogeneic cell therapy products. There are many inhibitory receptors that typically regulate T cell functionality—for example, PD-1, TIGIT, and TGF-b receptor. However, there are many other exciting intracellular molecules that could improve the persistence and functionality of CAR-T cells, such as Regnase-1, BLIMP-1, and DNMT3A, just to mention a few. There is a wealth of targets for us to hit in the potency space, which we see as the next realm for us to explore.

The second key thing for us is to get our lead therapeutic candidate for T cell malignancy moving into and through the clinic. This will demonstrate the real benefit of our technology, and we are already seeing how we compete relative to other products. Then, to flesh out our pipeline, we have one or two interesting solid tumor indications coming through, and we are also looking at an autoimmune disease as a potential target.

Even more broadly, we want to create universal donor cell therapies beyond CAR-T and engineered T cell therapies. Universal off-the-shelf therapies would mean that one day, our technology could play a key role in unlocking arguably the most significant challenge of the cell and gene therapy field—accessibility!

Last but not least, we are looking to leverage our platform technology. We are one of the few companies in this space that wholly owns a proprietary technology, so partnering it out will be a great opportunity for us. Other companies that are developing their own gene-engineered immunotherapies, universal donor cells, or in vivo gene therapies could benefit from adding our technology to fine-tune their own. We will actively partner with technology in different areas to complement and enable ongoing therapeutic developments.


Marco Alessandrini is the CEO and a member of the Board of Directors at Antion Biosciences, a Geneva-based cell and gene therapy company. He has over 15 years of experience in molecular medicine, and cell & gene therapy developments, and has led Antion’s R&D projects since 2016. Prior to Antion, he worked in the Pharma and Biotech industries in South Africa, before returning to academia at the Universities of Pretoria and then Geneva where he started his collaboration with the scientific founders of Antion. Since then, his work has been focused on developing a next generation of universal CAR-T cell therapies using the multiplex gene silencing technology developed at the University. In 2018, Marco started his transition to Antion, and in 2023 he was appointed as CEO of the company.


Marco Alessandrini
Antion Biosciences

Authorship & Conflict of Interest

Contributions: The named author takes responsibility for the integrity of the work as a whole, and has given their approval for this version to be published.

Acknowledgements: None.

Disclosure and potential conflicts of interest: Alessandrini M is in an active collaboration and license agreement with Allogene Therapeutics, where the company use Antion technology for development of its future pipeline of allogeneic therapeutics.

Funding declaration: The author received no financial support for the research, authorship and/or publication of this article.

Article & Copyright Information

Copyright: Published by Cell & Gene Therapy Insights under Creative Commons License Deed CC BY NC ND 4.0 which allows anyone to copy, distribute, and transmit the article provided it is properly attributed in the manner specified below. No commercial use without permission.

Attribution: Copyright © 2023 Alessandrini M. Published by Cell & Gene Therapy Insights under Creative Commons License Deed CC BY NC ND 4.0.

Article source: Invited.

Revised manuscript received: Dec 7, 2023; Publication date: Jan 11, 2024.