Jaehyun Choi, Co-CEO of Genexine, outlines the company’s transition from its established hyFc platform towards bioPROTAC, a novel protein degradation technology. He discusses GX-BP1, partnerships, regulatory challenges in Asia, and Genexine’s strategy of validating the platform through human proof-of-concept data before pursuing global licensing opportunities. His ambition is to establish Genexine as the global leader in bioPROTAC technology.
Can you briefly capture the company’s recent momentum and how you came to co-lead it?
Genexine was founded in 1999 and represents Korea’s first generation of biotech companies, built originally around DNA vaccine technology and hyFc, a long-acting protein platform. We have continued developing on those two foundations, and today we have several hyFc assets in later-stage development, some of which are already launched commercially in Indonesia and other South Asian markets, with further launches expected soon in China and elsewhere. I feel fortunate to have joined a company with that depth of history and platform expertise, but at the same time, Genexine recognised it needed a new platform technology to secure long-term future growth. Ahead of our 2024 merger, the company reviewed more than a hundred different platform technology companies, spanning antibody-drug conjugates, bispecific antibodies, targeted protein degradation, and other emerging modalities, to identify the right underlying technology for its next phase. Ultimately, Genexine chose EPD Biotherapeutics, which I had founded in 2021, and that is how I came to join.
Before founding EPD, I worked across Canada, Korea, and the US, and from 2019 I worked at Arvinas. Going in, the theoretical case for targeted protein degradation seemed very clear to me: it offered a genuinely distinct mechanism of action compared with small-molecule inhibitors or simple blocking antibodies. But during my time at Arvinas, I learned in far more depth about the real limitations of PROTAC, the small-molecule-based approach to protein degradation, through direct hands-on experience. That experience convinced me those limitations could be overcome through a biologics-based approach instead, which is why I founded my own company, EPD Biotherapeutics, in 2021. BioPROTAC itself was, at the time, a fairly open technology; many research groups had already published on the concept, but nobody had actually tried to develop it into a real drug for humans. I decided to be the one who did. Over the first three years, we built up in vitro and in vivo proof-of-concept data essentially from scratch, and it was after that three-year period that Genexine approached us about a merger, having become genuinely interested in the technology.
Given that the leading track record in protein degradation exists in the US, what makes Korea a strong place to develop this technology?
I cannot point to one single reason, but Korea has consistently focused on first-in-class drugs and novel targets, in a way that has felt almost cultural since my very first day in the industry here. Other countries, China for instance, may be stronger at developing best-in-class drugs building on existing science, but Korean companies have tended to gravitate toward genuinely new mechanisms and platforms. In practical terms, Korea also has a strong cluster of innovative companies specifically in the targeted protein degradation field, each developing their own distinct platforms, and being able to network and exchange ideas with them was genuinely valuable when I was building my own company. Orum Therapeutics, for example, has developed its own degrader antibody conjugate approach, and Prazer Therapeutics has developed its own platform as well. At the time I founded EPD, we were the only company pursuing the bioPROTAC approach specifically, but being surrounded by so many other innovative Korean companies working on adjacent protein degradation technologies was still genuinely energising.
As co-CEO of a fairly large biotech, how would you describe today’s business model, and how do you balance commercial partnerships against long-term innovation?
This is really the reason the co-CEO structure makes sense for Genexine at this stage. Because bioPROTAC remains relatively early-stage, it would be unrealistic to expect substantial revenue from it in the near term; we are still very much in development. Our hyFc platform, by contrast, is more mature and needs to generate meaningful income over the next few years to sustain the company. My co-CEO, Mr. Sungjune Hong, brings a financial and legal background, and he governs that side of the business, everything outside the science itself. Through his leadership, we have maintained strong relationships with our existing commercial partners, who continue executing well in their respective territories, and we expect to receive milestone payments and royalties from that work, which will form our revenue base for the next several years while bioPROTAC continues to mature.
Your hyFc pipeline includes assets in CKD-induced anemia and diabetes, several close to commercialisation. How do these partnerships work in practice?
We have brought several of these hyFc molecules through to Phase III and, in some cases, internal commercialisation, and for markets outside Korea we work with regional partners to handle commercialisation directly. In China and other emerging Asian markets specifically, we have established a joint venture with Kalbe Pharma, through which we are co-developing these assets together. It is worth noting that many interviews we have conducted across Asia describe genuine difficulty in partnering across different Asian markets, given how competitive and siloed relationships between companies in different countries can sometimes be. We see it differently: when it comes to business specifically, we simply talk business, and once we commit to a partnership, we remain genuinely loyal to it and try to sustain that relationship for the long term.
Are you also exploring commercial partnerships for these assets beyond Asia?
Our primary target markets for bringing genuinely new technology forward remain the US and Europe, but for these later-stage hyFc assets specifically, we are also actively pursuing opportunities in Latin America, the Middle East and North Africa region, and other parts of Asia. Given that pricing in many of these markets needs to remain more affordable, expanding into regions where our existing assets are a strong fit forms one part of our strategy, alongside our longer-term focus on innovation through the bioPROTAC platform.
Turning to your newer pipeline, what differentiates your bioPROTAC technology from traditional protein degradation approaches?
It is worth explaining the underlying mechanism, since this is really the core of what makes our approach distinct. Traditional PROTAC technology relies on three components, and the first is what is called a warhead, which functions as the target binder: by binding to a target protein, it triggers that protein’s degradation. The major limitation is that, of roughly 20,000 intracellular proteins, only around 6.8 percent are believed to have a binding pocket suitable for a small molecule at all. That means the remaining 93 percent of intracellular proteins simply cannot be addressed using conventional small-molecule degrader technology. Theoretically, though, if you use a biologic molecule as the target binder instead, you can bind essentially any intracellular target. This differs from antibody-drug conjugates too, where the antibody binds an extracellular portion of a protein purely to deliver a cytotoxic payload; in our case, the biologic binder itself engages the intracellular target directly, so no external payload is required at all. In terms of the addressable universe of target proteins, small-molecule approaches can reach only around 6.8 percent of the intracellular proteome, whereas our bioPROTAC approach can, in principle, reach the full range of intracellular targets. That is the fundamental differentiating point of our platform.
Your lead programme, GX-BP1, targets SOX2, long considered an undruggable oncogenic transcription factor. What is the significance of that target?
SOX2 is a well-known oncogenic transcription factor that the field has wanted to degrade for a very long time, precisely because it plays such a central role in driving cancer. The problem has always been that there was no viable small-molecule binder for it, so it remained undruggable using conventional approaches. Genexine is the first company in the world to achieve genuinely potent degradation of this transcription factor using a bioPROTAC approach. Technically, we are at a fairly advanced stage now, but because this is such a novel modality against such a novel target, the industry remains understandably conservative. Companies want to see everything proven independently: safety, biodistribution, pharmacokinetics, all of it, precisely because nobody has proven this approach before, so we have had to work through each element methodically, one at a time. To date, we have demonstrated meaningful in vivo efficacy, in vivo distribution, and safety data. The only remaining piece is human proof-of-concept data, and we have been in discussion with several global companies about licensing this asset ahead of entering clinical trials ourselves.
Our goal is a global licensing arrangement covering the major regulatory territories at once, ideally through a partner with the resources and infrastructure to run this efficiently across geographies such as the FDA and EMA without needing to repeat everything region by region. We genuinely view GX-BP1 as the flagship demonstration of our whole bioPROTAC platform, the clearest proof point that we can degrade what has historically been considered one of the most notoriously undruggable proteins in oncology, one closely tied to cancer stemness.
Since SOX2 relates closely to cancer stemness, how would this therapy fit alongside existing standards of care in lung cancer?
This would not be intended as a first-line treatment initially. Given that SOX2 is known to drive acquired resistance to standard therapies across most types of solid tumours, we see this as a combination approach, likely positioned in a second or third-line setting to help maintain or extend the effectiveness of existing standards of care, including therapies such as AstraZeneca’s lung cancer treatments. The real challenge that remains is delivery, but if we can identify a strong tissue-targeting delivery system, we believe this could ultimately be layered onto standard therapy across many solid tumour types to help overcome acquired resistance. Because targeting cancer stem cells directly addresses the most fundamental driver of that resistance, we genuinely believe this could be a significant advance, though realistically we recognise we cannot pursue every avenue with our own resources alone, which is precisely why we favour validating this platform and target through partnership with a global company that has considerably more resources to expand clinical development quickly.
With limited internal resources, can Genexine fund this programme through to Phase I alone, or does that depend on partnership?
This is genuinely one of the central questions we have been working through internally. It is technically possible for us to initiate and sustain a Phase I trial for this asset on our own, but doing so would require compromising on other priorities across the business, so we need to be strategic and creative about how we proceed. Our overriding priority is generating human proof-of-concept data as quickly as possible, and to do that efficiently, we believe partnership is the better path. We have been in active discussions with several potential partners toward that end, and ultimately we believe that route serves patients, Genexine, and our future partners better than pursuing this entirely alone.
You mentioned discussions with a Chinese partner on this asset. Given China’s growing role generating clinical data for multinational companies, how does that collaboration work?
Modality-wise, bioPROTAC is ultimately delivered as an mRNA therapy, since we need to deliver the underlying biologic via mRNA. Successful mRNA drug development depends on three equally important components: mRNA engineering itself, the lipid nanoparticle delivery system, and the payload, which is where Genexine’s expertise sits. For reasons I cannot fully explain, a number of genuinely excellent, innovative Chinese companies have built strong expertise specifically in mRNA engineering and lipid nanoparticle technology. We have been working with one such company on the lipid nanoparticle engineering for GX-BP1, and they see substantial potential in this programme too, to the point where they are interested in a broader co-development partnership, starting with generating human proof-of-concept data in China before expanding into other territories together.
Given recent tightening of Chinese regulatory pathways for investigator-initiated trials, has that affected your plans?
Until around April or May of this year, initiating our trial in China through an investigator-initiated study was our clear priority, working with an established investigator there. Since then, however, there have been regulatory changes affecting how these trials are approved, and the pathway has become considerably more difficult and slower than before. What I am hearing from our partner in China now is that reaching a new investigator-initiated trial approval there may not be straightforward for some time, so we are also actively considering Australia as an alternative route to secure that data.
Korea is also an option, and it has excellent clinical scientists and a hospital system capable of running trials to a very high standard. However, the regulatory requirements are particularly rigorous. The Ministry of Food and Drug Safety sets a high bar for novel platforms such as ours, which makes initiating an investigator-initiated trial in Korea considerably more challenging in practice than it might initially appear. We therefore need to assess each market pragmatically and pursue the route that allows us to generate the necessary data most effectively.
Looking beyond SOX2 and lung cancer, where else is the bioPROTAC platform being applied?
Our second programme, GX-BP2, targets atopic dermatitis and autoimmune disease more broadly, which illustrates that this platform is not limited to oncology at all. We are also exploring central nervous system applications, targeting proteins such as tau, alongside other neurological targets, provided we can solve the relevant delivery challenges for each.
Given how crowded the atopic dermatitis space already is, dominated by dupilumab and its biosimilars, why pursue that target?
Dupilumab remains the clear market leader, but what we consistently hear from clinicians is that a significant proportion of patients simply do not respond well to it, and there is a genuinely strong scientific rationale for why that is the case. GX-BP2 is designed to address a considerably broader range of the pathogenic pathways involved in atopic dermatitis, and while our supporting data so far comes from animal models rather than humans, those in vivo results have consistently supported our hypothesis that this approach could deliver meaningfully stronger efficacy than existing options.
Looking five years ahead, what does Genexine need to achieve to keep investors, the board, and partners satisfied?
I would frame this in the context of how perceptions of mRNA therapy itself have shifted. Two years ago, people outside the field would tell me mRNA therapy simply would not work, largely because of delivery challenges; today, thanks to rapid progress in mRNA engineering and lipid nanoparticle technology, those same people now describe mRNA therapy as the next major technology platform. I believe bioPROTAC can become another important payload category within that broader mRNA therapy field, alongside monoclonal antibodies. Our central mission for Genexine is to establish the company as the global leader in bioPROTAC technology, and the essential step toward that is proving human proof-of-concept data with GX-BP1, which would meaningfully persuade the broader industry that this can be a genuine treatment modality for humans. If we achieve that, I believe it opens the door to substantial and sustainable long-term revenue, because our real core strength lies in our ability to generate many different bioPROTAC assets against many different targets. Once the platform itself is validated through GX-BP1, we believe we can pursue continuous global licensing deals built on that foundation.
Our model will therefore remain focused primarily on discovery and licensing, with partners playing a central role in the subsequent development and commercialisation of our assets. Each target we pursue requires its own delivery system, and there are simply too many different delivery challenges for us to address internally across every target. We therefore need to draw on partners’ expertise in drug delivery and development for each programme, rather than attempting to build every capability ourselves.
How large is the team supporting all of this?
We currently have a total of around 65 to 70 people, including our research institute and all supporting functions, which is relatively modest compared with other Korean biotechs of similar ambition. That said, we do maintain our own dedicated clinical development team, since we are currently running a Phase III clinical trial in Europe, alongside our research centre and other support functions.
Is there a guiding management principle behind how you run the company?
I want Genexine to be run as a genuinely science-based Korean biotech, where scientific evidence is always the most important criterion in any decision we make. Science tends to be fairly black and white: something works, or it does not, and I believe grounding every major decision in that clarity is what should define the company, both internally and in how we are ultimately recognised.
Genexine has been around for 27 years, yet remains relatively little known outside Korea. Why do you think that is?
For many years, our international efforts centred on pursuing FDA and EU approval based on our earlier hyFc platform, our long-acting technology, through which we developed interleukin-7, essentially a T-cell amplifier. That work has largely been carried out through our US subsidiary, NeoImmuneTech, which is listed on KOSDAQ rather than more widely known internationally, and remains a fairly small, venture-style operation, which likely explains why the name has not been especially familiar internationally until now.
Given Korea’s growing role in biotech, where China and Korea now share much of the innovation once concentrated in the US, what role do you see Korea playing globally?
I would say Korea remains genuinely distinctive as a nation focused on pioneering new platforms and new technologies, again and again, which I think is something we do better than most other countries. When people discuss bispecific antibodies globally, for instance, I believe ABL Bio comes to mind as one of the recognised global leaders in that space, and similarly, when people discuss antibody-drug conjugates, LigaChem Biosciences has become one of the major global names. In essentially every significant platform technology, Korean companies have positioned themselves among the global leaders in that particular field. My genuine goal in running Genexine is for people to think of us the same way when the conversation turns to bioPROTAC technology specifically, in the same breath as companies like ABL Bio or LigaChem. Korea, I believe, is simply a nation well suited to producing that kind of genuinely innovative platform technology.
Is there anything else you would like global pharma partners and investors to know?
I would emphasise once more that with the bioPROTAC platform, we can, in principle, degrade essentially any problematic protein a company might want to target. For many global pharmaceutical companies, I believe this approach could resolve a number of longstanding challenges they have faced, and I genuinely want them to understand that differentiating point clearly. Because we remain at a relatively early stage, we have not yet been able to demonstrate this conclusively beyond preclinical data, and that is admittedly a limitation at this moment. That said, over five years of research on this platform, we have systematically covered every key area of preclinical development, so the technology is genuinely proven up through that stage. Given the right partnership with a global company, I believe we could accelerate this considerably toward the next level of development, and in doing so, address a number of significant unmet needs that many companies in this space continue to face.
