Genexine’s First-in-Class SOX2 Degrader GX-BP1 Achieves Up to 96% Tumor Growth Inhibition and Prevents Regrowth in Preclinical Studies
Genexine, Inc., a clinical-stage biotechnology firm focused on next-generation therapeutic platforms, has reported new preclinical findings for its innovative oncology candidate GX-BP1. The data were presented at the American Association for Cancer Research Annual Meeting 2026 in San Diego, drawing attention to the drug’s potential to overcome one of cancer research’s most persistent challenges—targeting transcription factors that have long been considered beyond the reach of conventional drug development.
GX-BP1 is a first-in-class bioPROTAC (biological proteolysis-targeting chimera) designed to selectively degrade SOX2, a transcription factor that plays a central role in tumor biology. SOX2 is widely associated with tumor progression, metastasis, cancer stem cell maintenance, and resistance to therapy. Despite its importance, it has historically been labeled “undruggable” because traditional small-molecule drugs cannot easily bind to and inhibit its function. Genexine’s bioPROTAC approach offers a novel solution by eliminating the protein altogether rather than attempting to block it.
A novel strategy to eliminate a key oncogenic driver
Unlike standard therapies that inhibit protein activity, GX-BP1 leverages the cell’s natural ubiquitin-proteasome system to degrade SOX2 directly. This mechanism allows for the complete removal of the protein, potentially delivering a more profound and sustained therapeutic effect. By targeting SOX2 at its source, GX-BP1 aims to disrupt the biological processes that drive tumor relapse, therapeutic resistance, and disease progression.
SOX2 is particularly important in maintaining cancer stem cell populations—subsets of tumor cells that are capable of self-renewal and are often responsible for recurrence after treatment. By eliminating SOX2, GX-BP1 may reduce these resistant cell populations and improve long-term treatment outcomes.
Strong monotherapy activity across models
The preclinical results presented by Genexine demonstrated that GX-BP1 exhibits significant anti-tumor activity even when used alone. In multiple experimental models, the candidate achieved approximately 70% tumor growth inhibition (TGI), highlighting its potential as a standalone therapy.
This level of efficacy is notable given the difficulty of targeting transcription factors. The findings suggest that direct protein degradation may provide a viable strategy for addressing previously inaccessible targets in oncology.
Enhanced outcomes in combination therapies
In addition to its standalone performance, GX-BP1 showed compelling results when used in combination with other cancer treatments. In chemotherapy-resistant tumor models, the candidate was able to restore sensitivity, effectively reversing resistance mechanisms that limit the effectiveness of standard therapies.
GX-BP1 also demonstrated synergy with targeted therapies, particularly osimertinib, a widely used epidermal growth factor receptor (EGFR) inhibitor. Resistance to EGFR-targeted therapies remains a major clinical challenge, often driven by adaptive signaling pathways and the persistence of cancer stem cells.
The data revealed that GX-BP1 suppressed SOX2-mediated resistance pathways, thereby enhancing the anti-tumor efficacy of osimertinib. Notably, while tumors treated with osimertinib alone eventually resumed growth, the combination of GX-BP1 with osimertinib completely prevented tumor relapse. This effect was accompanied by a marked reduction in cancer stem cell populations, indicating a deeper and more durable therapeutic response.
Significant synergy with chemotherapy regimens
The candidate also showed strong synergy when combined with commonly used chemotherapy agents such as carboplatin and paclitaxel. In these combination studies, GX-BP1 produced a clear dose-dependent response, with tumor growth inhibition ranging from 87% to 96%.
At higher doses, near-complete suppression of tumor growth was observed, underscoring the potential of GX-BP1 to significantly enhance the effectiveness of established chemotherapy regimens. These findings are particularly relevant for patients with advanced or refractory cancers, where treatment options are often limited and resistance is a major barrier to success.
A potential backbone therapy in oncology
Taken together, the results position GX-BP1 as a promising backbone therapy for combination treatment strategies. Its ability to enhance chemotherapy, improve targeted therapy outcomes, and address resistance mechanisms suggests broad applicability across multiple oncology settings, including chemotherapy, targeted therapy, and potentially immunotherapy.
The versatility of GX-BP1 also highlights the broader potential of Genexine’s bioPROTAC platform, which could be used to target other difficult-to-drug proteins in cancer and beyond.
Advancing delivery with lipid nanoparticle technology
A critical component of GX-BP1’s development is its delivery system. Genexine has developed a clinically relevant approach using a lung-targeted lipid nanoparticle (LNP) platform. This system enables efficient systemic delivery of GX-BP1 mRNA, with preclinical studies showing that more than 70% of the administered mRNA reaches lung tissue within 24 hours.
This targeted delivery is particularly advantageous for lung-related malignancies, as it allows for high local drug concentrations while potentially minimizing systemic exposure and side effects. The use of LNP technology also aligns with the growing adoption of mRNA-based therapeutics in the biopharmaceutical industry.
Progress toward clinical development
GX-BP1 has demonstrated a comprehensive preclinical profile, including in vivo efficacy, pharmacokinetics, biodistribution, and safety. These results provide a strong foundation for advancing the candidate into investigational new drug (IND)-enabling studies, a key milestone on the path to human clinical trials.
Genexine is actively seeking global licensing and strategic partnership opportunities to accelerate the development of GX-BP1 and expand its bioPROTAC-based pipeline. Collaborations with international pharmaceutical companies could play a crucial role in bringing this innovative therapy to market.
Leadership perspective
Jaehyun Choi, Ph.D., Chief Executive Officer and Head of Research and Development at Genexine, emphasized the significance of GX-BP1 as a differentiated therapeutic approach.
“GX-BP1 directly targets a central driver of cancer resistance, offering a novel mechanism that goes beyond traditional inhibition strategies,” he stated. “Its strong combination potential and robust preclinical profile position it as a promising next-generation therapeutic candidate. We are actively advancing discussions with global partners to move this program forward.”
The presentation of GX-BP1 at AACR 2026 highlights the growing momentum behind targeted protein degradation technologies in oncology. By enabling the direct elimination of previously undruggable proteins like SOX2, bioPROTACs have the potential to reshape the treatment landscape and address longstanding gaps in cancer therapy.
If these promising preclinical findings translate into clinical success, GX-BP1 could represent a significant advancement in the fight against resistant and relapsed cancers. More broadly, it underscores the transformative potential of innovative platforms that move beyond conventional drug design to directly target the fundamental drivers of disease.
About Genexine
Genexine is one of the first-generation biotechnology companies in South Korea, dedicated to developing innovative biologics to address unmet medical needs in patients with serious diseases. The company leverages its proprietary technology platforms, including the long-acting hyFc® platform, DNA vaccine technology, and the next-generation bioPROTAC platform, to develop novel therapeutics.
In particular, Genexine is advancing a pipeline of global first-in-class drug candidates based on its bioPROTAC platform, including GX-BP1 for lung cancer and GX-BP2 for atopic dermatitis. In addition, the company is progressing late-stage bio-better assets toward commercialization. Efesa® (GX-E4), a long-acting treatment for anemia in chronic kidney disease, is currently under regulatory review in Korea and other global markets for non-dialysis patients. GX-H9, a long-acting growth hormone, is also preparing for regulatory approval in China.
About EPDeg™ bioPROTAC
EPDeg™ bioPROTAC is a next-generation targeted protein degradation (TPD) technology that directly fuses a synthetic nanobody-based target-binding moiety with an E3 ligase. This design overcomes key limitations of conventional small molecule-based PROTAC approaches, enabling improved development efficiency and enhanced tissue specificity. By selectively degrading disease-causing proteins, EPDeg™ bioPROTAC offers a novel therapeutic strategy with the potential to address previously undruggable targets.
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