THIO-101 Part C DCR Signal Impressive but Evidence Package Trails Regulatory Bar by Wide Margin

MAIA Reports 90.5% DCR for Ateganosine in Phase II NSCLC Trial

MAIA Biotechnology announced positive initial efficacy results from Part C of its Phase II THIO-101 trial for ateganosine, its lead candidate, as a third-line treatment for advanced non-small cell lung cancer (NSCLC). The study reported a disease control rate (DCR) of 90.5% among 21 efficacy-evaluable patients, with 19 showing disease control. Patients received ateganosine followed by cemiplimab on a 21-day cycle. The combination demonstrated an acceptable safety profile in this heavily pre-treated population, consistent with earlier parts of the trial which showed an 88% DCR, nearly triple that of standard-of-care chemotherapy.

• Significant Efficacy in Heavily Pre-treated NSCLC: The Phase II THIO-101 trial's Part C demonstrated a 90.5% disease control rate (DCR) in 21 efficacy-evaluable patients with advanced non-small cell lung cancer. This patient cohort was particularly challenging, having received extensive prior treatments including docetaxel, and showing resistance to both immunotherapy and other chemotherapies, highlighting ateganosine's potential in a difficult-to-treat population.
• Consistent Efficacy and Acceptable Safety Profile: The initial efficacy data from Part C aligns with previous encouraging signals from Parts A and B of the THIO-101 trial, which reported an 88% DCR in third-line NSCLC patients. The combination of ateganosine followed by cemiplimab continues to exhibit an acceptable safety profile, which is crucial for a heavily pre-treated patient group, supporting its continued development.
• Novel Mechanism of Action and Combination Therapy: Ateganosine, also known as THIO, is an investigational telomere-targeting agent designed to induce telomerase-dependent DNA modification and selective cancer cell death while activating immune responses. Its administration followed by a PD-(L)1 inhibitor, cemiplimab, represents a strategic combination approach aimed at enhancing anti-tumor activity in patients who have progressed on prior checkpoint inhibitor treatments.

Addressing the Critical Unmet Need in Advanced NSCLC

Despite meaningful advances in surgical techniques, chemotherapy, and chemoradiotherapy over recent decades, the long-term survival outlook for patients with advanced NSCLC has not improved commensurately. Median survival for patients treated with platinum-based doublet chemotherapy — the current standard of care — remains a disappointing 8–10 months, with chemotherapy in stage IV disease offering a largely palliative effect of limited duration. Only minor gains have been achieved over the past decade in prolonging survival or improving quality of life in patients with good performance status, and no definitive cure exists for advanced NSCLC. Second-line chemotherapy has demonstrated minimally improved survival compared to best supportive care, and most patients ultimately experience treatment failure, resulting in poor prognosis characterized by low median progression-free survival (PFS) and overall survival (OS).

A defining challenge across all treatment modalities is the near-universal emergence of resistance. Resistance to initial therapy is universal, and targeted therapies and immune checkpoint inhibitors face the same fundamental limitation as conventional agents — the development of resistant mechanisms. Compounding this, the lack of robust predictive biomarkers makes patient selection for therapies that will deliver the greatest benefit increasingly complex. The therapeutic ratio of systemic treatments remains in need of improvement, particularly for older patients — those above 65 years of age typically exhibit declining organ function and reduced physiological reserve, limiting their tolerance for intensive regimens such as immunotherapy combined with platinum-based doublet chemotherapy.

The rapidly evolving treatment landscape, while representing genuine scientific progress, has introduced its own clinical challenges. The recent success of targeted therapies and immune checkpoint inhibitors has substantially expanded the complexity of treatment decision-making for healthcare providers. Treatment options remain constrained by drug resistance and toxicity, and approaches to preventing metastases and overcoming resistance are necessary to ensure long-term survival. These persistent limitations collectively underscore the urgent need for novel therapeutic strategies capable of delivering durable responses with manageable safety profiles across a broad and heterogeneous patient population.

Unpacking the THIO-101 Design and Ateganosine's Telomere-Targeting Approach

The THIO-101 trial and ateganosine's development have been informed by a broad landscape of clinical evidence in advanced NSCLC, spanning targeted therapy, immunotherapy, and combination regimens. The trials below represent a cross-section of pivotal and supportive studies that define current standards of care and inform endpoint selection in this setting.

Initial Efficacy and Safety Data for Ateganosine in Heavily Pre-treated NSCLC

Recent clinical evidence in advanced NSCLC spans a range of therapeutic strategies — from targeted agents in mutation-defined populations to immunotherapy combinations and second-line salvage regimens. The studies below represent key data readouts informing current and emerging treatment paradigms.

• PAPILLON Study (Phase III; NCT04538664): Evaluated first-line amivantamab (IV every 3 weeks) combined with carboplatin (4 cycles) and pemetrexed (until progression) versus chemotherapy alone in 308 patients with EGFR exon 20 insertion-mutated NSCLC (amivantamab-chemotherapy, n=153; chemotherapy, n=155). At a median follow-up of 14.9 months, the combination demonstrated significantly prolonged progression-free survival. Median time to treatment discontinuation was 13.2 vs. 7.5 months (HR 0.38, 95% CI 0.28–0.51; p<0.0001), and median time to subsequent therapy was 17.7 vs. 9.9 months (HR 0.35, 95% CI 0.25–0.49; p<0.0001). Crossover-adjusted OS yielded HRs of 0.52–0.60, more pronounced than the planned interim intention-to-treat OS (HR 0.67, 95% CI 0.42–1.09), with 65/155 chemotherapy-arm patients crossing over to amivantamab post-progression.

• ALEX Study (Phase III — Final Analysis, 2025): Compared alectinib 600 mg twice daily versus crizotinib 250 mg twice daily in 303 treatment-naïve patients with stage III/IV ALK-positive NSCLC (alectinib n=152; crizotinib n=151). At a data cutoff of April 28, 2025 (median follow-up 53.5 vs. 23.3 months), median OS was 81.1 months (95% CI 62.3–NE) vs. 54.2 months (95% CI 34.6–75.6; HR 0.78, 95% CI 0.56–1.08). OS benefit was most pronounced in patients with CNS metastases (63.4 vs. 30.9 months; HR 0.68). Median duration of response was 42.3 vs. 11.1 months (HR 0.41, 95% CI 0.30–0.56). Long-term safety over a median alectinib treatment duration of 28.1 months was consistent with earlier reports, with no new or unexpected safety signals.

• SAFFRON-301 Study (Phase III, 2026): Open-label trial (NCT04921358) randomizing 377 patients with unresectable locally advanced/metastatic NSCLC — who had progressed on prior platinum-based chemotherapy and anti-PD-(L)1 therapy — to sitravatinib plus tislelizumab (n=187) or docetaxel (n=190). Median OS was 11.5 vs. 11.4 months (HR 1.02, 95% CI 0.75–1.39); IRC-assessed median PFS was 4.4 vs. 2.9 months (HR 0.82, 95% CI 0.62–1.07); ORR was 12.3% vs. 12.6%. Grade ≥3 AEs in the investigational arm included hypertension (13.4%), pneumonia (9.1%), and palmar-plantar erythrodysesthesia syndrome (6.5%); grade 5 haemoptysis occurred in 3 patients (1.6%) receiving sitravatinib plus tislelizumab. The study was terminated early due to an unfavourable risk-benefit assessment in the investigational arm.

• eXalt3 Study (Phase III): Global randomized open-label trial comparing ensartinib (second-generation ALK inhibitor) versus crizotinib as first-line therapy in 290 patients with advanced ALK-rearranged NSCLC across 120 centers in 21 countries. Ensartinib demonstrated a statistically significant improvement in progression-free survival over crizotinib and exhibited stronger activity against both systemic disease and brain metastases, supporting its approval as a first-line treatment option in this molecular subgroup.

• ENTRÉE Lung Platform Trial Sub-study 1 (Phase II, 2026; NCT03739710): Evaluated feladilimab (an IgG4 inducible T-cell costimulator agonist antibody) 80 mg plus docetaxel 75 mg/m² (n=70) versus docetaxel monotherapy (n=35), both IV every 3 weeks, in 105 patients with advanced/recurrent NSCLC who had progressed on prior anti-PD-(L)1 and platinum-based chemotherapy. Median OS was 7.8 vs. 8.2 months (HR 1.5, 95% CI 0.92–2.44); median PFS was 3.4 vs. 3.3 months (HR 0.84, 95% CI 0.54–1.32); ORR was 19% vs. 11%. Frequently reported treatment-related AEs with the combination included anemia (34%), nausea (34%), alopecia (27%), and asthenia (27%). The combination showed an acceptable safety profile but conferred no improvement in survival outcomes or tumor response over docetaxel alone.

• Meta-analysis of PD-1/PD-L1 Inhibitors in Elderly NSCLC Patients (2025): Systematic review and meta-analysis of 12 RCTs encompassing 3,078 elderly patients with NSCLC, comparing PD-1/PD-L1 inhibitors to placebo and/or chemotherapy. PD-1/PD-L1 inhibition significantly improved OS (HR 0.76, 95% CI 0.69–0.84; p<0.001) and event-free survival (HR 0.67, 95% CI 0.54–0.83; p<0.001), with consistent benefit observed across large individual studies.

• Meta-analysis of Atezolizumab versus Docetaxel (2025): Systematic review of 10 double-blind RCTs involving 3,445 patients receiving atezolizumab and 3,018 receiving docetaxel. Atezolizumab demonstrated superior OS overall (HR 0.77, 95% CI 0.73–0.81) and in PD-L1-positive (HR 0.72) and PD-L1-negative (HR 0.78) subgroups, as well as improved PFS (HR 0.93, 95% CI 0.88–0.99); no benefit in ORR or PFS was observed in PD-L1-negative patients. Atezolizumab was associated with a markedly lower incidence of grade 3–5 AEs (OR 0.21, 95% CI 0.15–0.28) and lower treatment discontinuation rates (OR 0.35, 95% CI 0.20–0.61) compared with docetaxel. Notably, no direct linear relationship between atezolizumab efficacy and PD-L1 expression status was identified.

Positioning Ateganosine in the Advanced NSCLC Treatment Landscape

The treatment landscape for advanced NSCLC has evolved substantially, with multiple classes of investigational and approved agents demonstrating meaningful improvements over historical standard-of-care chemotherapy. A pivotal meta-analysis of 13 studies encompassing 6,585 patients confirmed that immunotherapy significantly improved both progression-free survival (OR 1.81, 95% CI 1.36–2.42; P<0.0001) and overall survival (P<0.0001) compared to standard chemotherapy or placebo, while also reducing the burden of toxic adverse effects that have long limited chemotherapy utility. Among targeted therapies, the FLAURA trial established osimertinib's superiority over first- and second-generation EGFR-TKIs, with a median OS of 38.6 versus 31.8 months (HR 0.80; 95% CI 0.641–0.997; P=0.046), a 52% reduction in CNS progression risk (HR 0.48; P=0.014), and 28% of patients remaining on treatment at three years compared to just 9% in the comparator arm. In second-line settings, pemetrexed demonstrated superior median OS of 10.5 months versus 8.0 months for sunitinib and 6.7 months for the combination (P=0.03), alongside a more favorable toxicity profile.

Immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 have demonstrated particular clinical relevance across multiple patient subpopulations. In patients with brain metastases from lung cancer — historically an underserved population — PD-1/PD-L1 inhibitors versus chemotherapy significantly prolonged OS (HR 0.75, 95% CI 0.51–0.99) and PFS (HR 0.65, 95% CI 0.51–0.80) in a meta-analysis of 694 patients across 11 randomized controlled trials. Real-world data further support the effectiveness of pembrolizumab, with an Australian population-based study reporting a median OS of 13.2 months in routine clinical practice, though this remained below outcomes observed in pivotal trials. Notably, KRAS-mutated tumors exhibited more pronounced survival benefit with pembrolizumab compared to KRAS wild-type disease, and the NSCC-NOS histological subtype demonstrated exceptional responsiveness to first-line PD-1/PD-L1 inhibitors, with median PFS of 14.8 versus 6.1 months and median OS of 33.4 versus 15.1 months compared to non-NSCC-NOS patients (P=0.04 and P<0.01, respectively).

From a safety and tolerability perspective, the comparative profiles of investigational agents vary considerably. Real-world ICI cohort data indicate that 34% of patients develop immune-related adverse events, with 17% reaching CTCAE Grade ≥3; however, the development of irAEs was independently associated with improved OS (HR 0.644; P=0.036), suggesting an immunological correlate of treatment benefit. Conversely, trastuzumab deruxtecan in HER2-mutant NSCLC carried a notable safety burden, with Grade ≥3 drug-related adverse events in 46% of patients and adjudicated interstitial lung disease in 26%. In contrast, lower-dose osimertinib regimens (20–40 mg) in EGFR-mutated patients demonstrated a predominantly Grade 1 adverse event profile with no Grade 3/4 events reported. Baseline inflammatory biomarkers — including CRP ≥10 mg/L (HR 2.064; P=0.0003) and eosinophil count ≤0.2 × 10⁹/L (HR 2.252; P=0.002) — have emerged as independent predictors of mortality in ICI-treated populations, underscoring the importance of patient selection and biomarker-informed treatment strategies in this evolving landscape.