[Edaily Reporter NA EUN-KYUNG ] “While most of the meetings at Bio USA are related to APX-115, there is also considerable interest in APTA-16, which is still in the preclinical stage. This is because global pharmaceutical companies are seeking new modalities beyond antibody-drug conjugates (ADCs).”

Aptabio Therapeutics Inc.(293780)APTA-16, an aptamer-drug conjugate (APTA-DC)-based anticancer drug currently under development, is attracting interest from global pharmaceutical companies. According to the company, among the approximately 30 business meetings scheduled for this month at the “Bio International Convention” (BIO USA 2026) in Boston, discussions regarding APX-115—a treatment for diabetic nephropathy—are the most frequent; however, inquiries about APTA-16, the company’s next-generation anticancer platform, are also more active than expected.

Lee Soo-jin, CEO of Aptabio Therapeutics Inc., met with E-Daily on the 18th at the company’s headquarters in Yongin, Gyeonggi Province, and said, “While various modalities such as ADCs and bispecific antibodies have advanced, there is a sense of crisis within global pharmaceutical companies that the ADC sector has become excessively competitive.” She added, “Recently, interest has been growing in new platforms that can prepare for the post-ADC era.”

“Concerns Over ADC ‘Red Ocean’”… Big Pharma Explores Next-Generation Platforms

APTA-16, currently under development by Aptabio Therapeutics Inc., is a treatment for relapsed/refractory acute myeloid leukemia (R/R AML). However, CEO Lee Soo-jin places greater emphasis on the value of the underlying APTA-DC platform than on APTA-16 itself.

CEO Lee explained that the history of anticancer drug development is ultimately a process of advancing “precision targeting technology.” While the field has evolved from cytotoxic anticancer drugs to targeted anticancer drugs, and then to antibody therapies, ADCs, and bispecific antibodies, issues of resistance and toxicity remain unresolved.

In particular, while ADCs have recently emerged as the largest investment area in the global pharmaceutical industry, their limitations are clear. Since only a small amount of drug can be bound to an antibody, highly toxic toxins must be used, and there is a risk of serious side effects if the drug dissociates from the antibody in the bloodstream earlier than expected. In fact, there has recently been a growing trend toward using relatively safer anticancer drugs instead of conventional toxins to reduce toxicity.

Aptabio Therapeutics Inc. claims that its APTA-DC platform can overcome these limitations. This approach uses aptamers instead of antibodies to recognize targets and loads existing anticancer drugs rather than highly toxic toxins. Aptamers are DNA- or RNA-based nucleic acid molecules designed to bind selectively to specific targets; they possess target-recognition capabilities similar to those of antibodies while being smaller in size and capable of chemical synthesis.

CEO Lee explained, “Aptamers possess target recognition capabilities comparable to those of antibodies while exhibiting virtually no immunogenicity (the potential to trigger an immune response in the body),” adding, “Since they are loaded with first-line anticancer drugs whose safety has already been proven, this enhances the overall safety of the platform.”

G-Quadruplex: Overcoming the Limitations of Aptamers

Aptamers themselves are not a new technology. They first appeared in the 1990s, and in 2004, “Macugen,” a treatment for age-related macular degeneration, was approved as the world’s first aptamer-based therapy. However, since then, aptamer-based therapies have not seen significant growth, overshadowed by antibody therapies.

CEO Lee identified in-vivo stability and productivity as the biggest issues with early aptamer technology. “Conventional aptamers are degraded within minutes by DNA and RNA-degrading enzymes once they enter the body,” he explained. “To prevent this, various chemical modifications and polyethylene glycol (PEG) were attached, but this significantly increased production costs and reduced yield.”

Aptabio Therapeutics Inc. has improved the in vivo stability limitations of existing aptamers by utilizing a G-quadruplex structure.

CEO Lee said, “While existing aptamer therapeutics used chemical modification of DNA to ensure stability, we applied a G-quadruplex structure in which the DNA itself folds into four strands,” adding, “We were able to ensure both stability and ease of development.”

According to him, while conventional aptamers degrade within minutes, G-quadruplex-based aptamers achieved a half-life of up to several hours in animal experiments.
“Assembled

like LEGO”… AML as the First Test Bed

Another feature of APTA-DC is that it does not require a linker.

In existing ADCs, the design of the linker connecting the antibody and the drug is one of the core technologies. However, linker development, quality control (QC), and the production process incur significant costs. In contrast, APTA-DC is developed by directly embedding the drug within the aptamer sequence, eliminating the need for a separate linker.

CEO Lee said, “APTA-DC is like Lego,” adding, “It is a platform that allows us to design customized therapies for specific diseases by combining the optimal target with the optimal drug.”

Aptabio Therapeutics Inc. is currently developing APTA-16 as the first candidate to validate the platform. APTA-16 is loaded with cytarabine, which is used to treat patients with relapsed or refractory AML, and the company aims to enter Phase 1 clinical trials this year.

APTA-16 was developed after AML was selected as the first indication to rapidly validate the APTA-DC platform’s proof of concept (PoC). This is because, in blood cancers, the response of cancer cells and changes in biomarkers can be directly observed in the patient’s bone marrow, allowing for a faster evaluation of drug efficacy in early-stage clinical trials compared to solid tumors. CEO Lee added, “Furthermore, since treatment options for relapsed or refractory AML are limited, we considered it a suitable first testing ground for APTA-16.”

Meanwhile, Aptabio Therapeutics Inc. plans to hold business development meetings at this year’s Bio USA regarding ABF-101, an oral treatment for age-related macular degeneration, in addition to APX-115, APX-343A, and APTA-16. APX-115 is a novel drug candidate in the class of pan-NADPH oxidase (NOX) inhibitors and is currently undergoing a global Phase 2 clinical trial in patients with moderate-to-severe diabetic nephropathy.

CEO Lee stated, “Currently, sodium-glucose cotransporter-2 (SGLT-2) inhibitors and glucagon-like peptide (GLP)-1 agonists on the market are primarily used for patients in the early stages of the disease,” adding, “We are targeting the severe patient population for whom treatment options are limited.” He continued, “We expect to receive topline results from the global Phase 2 clinical trial of APX-115, a treatment for contrast-induced acute kidney injury, in late September or early October.” Aptabio Therapeutics Inc. plans to begin full-scale discussions on technology transfer based on these results.

He said, “While APX-115 is the pipeline candidate drawing the most interest, we are also receiving more inquiries than expected regarding APTA-16 and ABF-101,” adding, “We plan to actively seek global partnership opportunities in line with the development stage of each pipeline.”