SK biopharmaceuticals to report preclinical data on NTSR1-targeted RPT at AACR 2026
SK biopharmaceuticals said it will present preclinical findings on its radiopharmaceutical therapy candidate SKL35501 and diagnostic agent SKL35502 at the 2026 American Association for Cancer Research Annual Meeting.
The company will use AACR 2026 to present preclinical data from its NTSR1-targeted radiopharmaceutical program, highlighting both its theranostics strategy and the rapid advancement of the pipeline toward clinical-stage development.
Date: April 8, 2026
Key facts
- SK biopharmaceuticals will present preclinical data on SKL35501 and SKL35502 at AACR 2026.
- The program targets NTSR1 (Neurotensin Receptor 1), which is highly expressed in multiple solid tumors, including colorectal and pancreatic cancers.
- SKL35501 uses the alpha-emitting radionuclide actinium-225 (225Ac) as a targeted therapeutic approach.
- SK biopharmaceuticals said it advanced the pipeline to the clinical trial stage in about 18 months from inception.
SK biopharmaceuticals said it would present research findings on its radiopharmaceutical therapy candidate SKL35501 and diagnostic agent SKL35502 at the 2026 American Association for Cancer Research Annual Meeting. AACR is one of the world’s leading cancer research conferences, where researchers and companies from around the world share the latest oncology findings. This year’s event is scheduled for April 17 to April 22 in San Diego, California.
The presentation will unveil preclinical data from SK biopharmaceuticals’ NTSR1-targeted radiopharmaceutical therapy program, a component of the company’s next-generation anticancer portfolio. Notably, SK biopharm said it advanced this pipeline to the clinical trial stage in about 18 months from inception, underscoring the pace at which it is building out its radiopharmaceutical platform.
NTSR1-targeted theranostics strategy focuses on precision oncology
NTSR1, or Neurotensin Receptor 1, is highly expressed in several solid tumors, including colorectal cancer and pancreatic cancer. Using a theranostics strategy that integrates therapeutic and diagnostic development, SK biopharmaceuticals is applying a precision medicine approach that uses diagnostic agents to identify NTSR1-positive patients and then connect those patients with a matched targeted therapy.
By presenting preclinical data for its NTSR1-targeted radiopharmaceutical program on an international stage, the company aims to showcase both its technological capabilities and the broader direction of its next-generation oncology research. In practical terms, the AACR presentation is positioned as both a scientific disclosure and a strategic signal about where SK biopharmaceuticals sees future growth in cancer therapeutics.
SKL35501 showed tumor specificity, retention and antitumor activity
The NTSR1-targeted therapy SKL35501, which uses the alpha-emitting radionuclide actinium-225, demonstrated high tumor specificity and prolonged retention in the HCT116 human colorectal cancer cell model. Within 24 hours, the therapy showed strong tumor accumulation, reaching 31 percent ID/g, and this selectivity remained consistent for up to 168 hours.
In addition, a dose-dependent inhibition of tumor growth was observed even after a single administration, and all dose groups demonstrated significantly prolonged survival compared with controls. Tumor shrinkage was reported in selected dose groups, highlighting the antitumor activity and therapeutic promise of SKL35501. The company also said the drug cleared rapidly from non-target organs, supporting its potential as a first-in-class therapeutic candidate.
The company is positioning its NTSR1-targeted radiopharmaceutical program as a key part of its next-generation anticancer portfolio, combining targeted therapy and diagnostics within a single theranostics framework.
SKL35502 supports diagnostic selection of NTSR1-positive patients
Preclinical results for SKL35502 will also be presented at AACR 2026. In the HCT116 model, SKL35502 showed high sensitivity, with tumor exposure reported at about 22 times higher than in blood. After 96 hours, 84 percent of the administered radioactivity had been excreted.
These findings suggest that strong tumor signal intensity can be maintained while minimizing off-target tissue burden. That balance is important for a theranostics strategy, because the value of a diagnostic agent lies not only in tumor detection, but also in its ability to help select patients likely to benefit from the corresponding targeted radiopharmaceutical therapy.
IND approvals move SKL35501 and SKL35502 toward first-in-human trials
SK biopharmaceuticals received investigational new drug approvals for Phase 1 clinical trials from both South Korea’s Ministry of Food and Drug Safety and the U.S. Food and Drug Administration for SKL35501 and SKL35502 in January. The company said it plans to begin a first-in-human clinical trial in patients with solid tumors that overexpress NTSR1.
SK biopharmaceuticals CEO Lee Dong-hoon said the AACR presentation represents a pivotal moment as the company shares the accomplishments of its radiopharmaceutical therapy pipeline on a global platform for the first time. He added that the company would accelerate radiopharmaceutical therapy development and strengthen global research and development efforts to deliver innovative treatments for patients.
Taken together, the AACR 2026 presentation is expected to provide one of the clearest public looks so far at SK biopharmaceuticals’ NTSR1-targeted theranostics strategy. For the company, the combination of preclinical efficacy, diagnostic targeting, and early regulatory progress appears to support a broader ambition to establish radiopharmaceutical therapy as a core pillar of its future oncology pipeline.
