$ATNMJun 3, 2026, 8:01 AM ETAI processed
ATNM-400 drives regressions and combo cures in preclinical KRAS/EGFR NSCLC models
AI Summary
Actinium presented SNMMI preclinical data showing ATNM-400 (an Ac-225 antibody radioconjugate) produced tumor regressions as a monotherapy in KRAS-mutant models and achieved complete cures when combined with osimertinib in an EGFR-mutant model; sotorasib and adagrasib increased the ATNM-400 target ~3.5–3.8x and combinations enhanced tumor-cell killing. The company positions ATNM-400 as a potential mutation-agnostic NSCLC backbone because the target is reported present in ~98% of NSCLC tumors (highly expressed in ~70%), but the results are preclinical and activity is dependent on target expression, so clinical translation and human safety remain unproven.
Positives
- ATNM-400 produced tumor regressions in KRAS models and single-dose deep responses with clean tolerability in animals
- Combination with osimertinib produced complete tumor regressions (100% cures in mice) in an EGFR model
- Approved KRAS inhibitors (sotorasib, adagrasib) raised target expression ~3.5–3.8x and combos further decreased viability, supporting combo strategy
Negatives
- All data are preclinical (cell lines and animal models); no clinical efficacy or human safety data presented
- Activity is target-dependent — one tested line (A549) was target-negative and did not bind ATNM-400
- Translational risk remains high: mouse tolerability and tumor regressions may not predict human outcomes or dosing/safety