Ateganosine Receives FDA Fast Track Designation for NSCLC

MAIA Biotechnology’s investigational telomere-targeting agent, ateganosine (THIO, 6-thio-2’-deoxyguanosine, or 6-thio-dG), has been granted fast track designation by the US FDA for the treatment of advanced non–small cell lung cancer (NSCLC) that has progressed after immune checkpoint inhibitor therapy.¹ The designation is based on promising early clinical data from the ongoing THIO-101 trial (NCT05208944), which is evaluating ateganosine in combination with cemiplimab (Libtayo) in this patient population.

Fast Track Designation and Clinical Implications

The FDA’s fast track program is designed to expedite the development and review of drugs that treat serious conditions and fill unmet medical needs.² For patients with advanced NSCLC who have progressed on or after immune checkpoint inhibitors, treatment options remain limited, underscoring the potential significance of ateganosine.¹

Ateganosine is a first-in-class small molecule that targets telomeres, the protective caps at the ends of chromosomes that shorten with each cell division. Cancer cells rely on telomerase to maintain telomere length, enabling uncontrolled proliferation. Ateganosine acts as a direct telomere-targeting agent, disrupting this mechanism and inducing cancer cell death.

“FDA’s Fast Track Designation recognizes ateganosine’s potential as a new therapeutic paradigm in cancer treatment science. Ateganosine is the first and only anticancer treatment of its kind that we are aware of in clinical development,” said Vlad Vitoc, MD, MAIA’s chairman and CEO, in the press release. “If we are successful in the Fast Track regulatory pathway, ateganosine could qualify for accelerated FDA approval and robust exclusivity in NSCLC, with a potential FDA decision as early as next year. If approved, ateganosine would have a first-to-market competitive position within a $34 billion NSCLC treatment market with significant unmet medical need.”

THIO-101 Trial Design and Preliminary Data

The ongoing THIO-101 trial (NCT05208944) is a phase 2, open-label study evaluating ateganosine sequentially followed by cemiplimab in patients with advanced NSCLC who have progressed after platinum-based chemotherapy and anti–PD-1/PD-L1 therapy. The trial is assessing safety, tolerability, and preliminary efficacy, including objective response rate and progression-free survival.³

Updated data were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting and results showed that, across all ateganosine dose levels, partial responses (PRs) occurred in 10 patients, which included 6 in the second-line setting and 4 in the third-line setting. Through a second scan via investigator assessment, there were 4 PRs in each of the 2 settings. The disease control rate overall was 77%.⁴

Mechanistic Rationale for Ateganosine in NSCLC

Ateganosine is metabolized into 6-thio-dGTP, which is incorporated into telomeres by telomerase, leading to telomere dysfunction and selective cancer cell death. Preclinical studies have suggested that ateganosine may also enhance the activity of immune checkpoint inhibitors by increasing tumor immunogenicity, providing a strong rationale for its combination with cemiplimab.

Next Steps and Future Development

With fast track designation, MAIA will have more frequent interactions with the FDA to streamline THIO’s development path. If subsequent trial results remain positive, the company may pursue accelerated approval. Additional studies exploring ateganosine in other solid tumors are also under consideration.

REFERENCES:

1. MAIA Biotechnology Receives FDA’s Fast Track Designation for Ateganosine as a Treatment for Non-Small Cell Lung Cancer. News release. MAIA Biotechnology. July 28, 2025. Accessed July 28, 2025. https://tinyurl.com/58nzpra5

2. Fast Track. US Food & Drug Administration. Updated August 13, 2024. Accessed July 28, 2025. https://tinyurl.com/y748ywj9

3. THIO Sequenced With Cemiplimab in Advanced NSCLC. ClinicalTrials.gov. Updated May 31, 2025. Accessed July 28, 2025. https://clinicaltrials.gov/study/NCT05208944

4. Jankowski T, Csõszi T, Urban L, et al. Phase 2 study of telomere-targeting agent THIO sequenced with cemiplimab in third-line immune checkpoint inhibitor–resistant advanced NSCLC: evaluation of overall survival (OS). J Clin Oncol. 2025;43(suppl_16):8585. doi:10.1200/JCO.2025.43.16_suppl.8585