On June 5, 2025 MAIA Biotechnology, Inc. (NYSE American: MAIA) ("MAIA", the "Company"), a clinical-stage biopharmaceutical company focused on developing targeted immunotherapies for cancer, reported a new partial response (PR) was identified in a patient after 20 months of treatment in its Phase 2 THIO-101 clinical trial evaluating ateganosine (THIO), sequenced with Regeneron’s immune checkpoint inhibitor (CPI) cemiplimab (Libtayo) in patients with advanced non-small cell lung cancer (NSCLC) who are resistant to immune therapy and chemotherapy (Press release, MAIA Biotechnology, JUN 5, 2025, View Source [SID1234653750]). A partial response is defined as a decrease in tumor size of at least 30%.

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"The patient remained on treatment and we observed stable disease for more than twenty months before the partial response was identified, highlighting the efficacy, safety and low toxicity of the treatment. Extended-term responses like this are not often seen in heavily pretreated patients in hard-to-treat diseases such as NSCLC, where the prognosis for the advanced-stage of the disease is typically poor," said MAIA Chairman and CEO Vlad Vitoc, M.D. "We confirmed this response with a second scan, and we are highly confident that ateganosine could become an outstanding therapeutic alternative for third-line NSCLC patients."

THIO-101 third line (3L) data cutoff from May 15, 2025, showed median overall survival (OS) of 17.8 months for the 22 NSCLC patients who received at least one dose of ateganosine in parts A and B of the trial. At the data cutoff, the patient with the longest survival in the trial had completed 32 cycles of therapy and had 24.3 months survival. Studies of standard-of-care (SOC) chemotherapy treatments for NSCLC in a similar setting have shown OS of 5 to 6 months.1

MAIA has announced the trial design for an expansion of its THIO-101 pivotal Phase 2 trial in NSCLC to assess overall response rates (ORR) in advanced NSCLC patients receiving third line (3L) therapy who were resistant to previous CPI treatment and chemotherapy.

About Ateganosine

Ateganosine (THIO, 6-thio-dG or 6-thio-2’-deoxyguanosine) is a first-in-class investigational telomere-targeting agent currently in clinical development to evaluate its activity in non-small cell lung cancer (NSCLC). Telomeres, along with the enzyme telomerase, play a fundamental role in the survival of cancer cells and their resistance to current therapies. The modified nucleotide 6-thio-2’-deoxyguanosine induces telomerase-dependent telomeric DNA modification, DNA damage responses, and selective cancer cell death. Ateganosine-damaged telomeric fragments accumulate in cytosolic micronuclei and activates both innate (cGAS/STING) and adaptive (T-cell) immune responses. The sequential treatment of ateganosine followed by PD-(L)1 inhibitors resulted in profound and persistent tumor regression in advanced, in vivo cancer models by induction of cancer type–specific immune memory. Ateganosine is presently developed as a second or later line of treatment for NSCLC for patients that have progressed beyond the standard-of-care regimen of existing checkpoint inhibitors.