Actinium reports early ATNM-400 data and plans an ESMO Phase 1 presentation
Actinium Pharmaceuticals reported initial Phase 1 results for ATNM-400 in metastatic castration-resistant prostate cancer after the first three patients completed treatment at 1.0 µCi/kg without dose-limiting toxicities, allowing escalation to 1.5 µCi/kg. The HER3-targeted Actinium-225 therapy is administered every six weeks for up to four cycles, with the study designed to identify a recommended Phase 2 dose. Actinium also announced that the trial would be featured at the ESMO Congress 2026 from October 23–27, while separate work examined the therapy in KRAS- and ALK-driven non-small-cell lung cancer models.
Why it matters
The dose escalation gives Actinium additional safety and dosing information as it works toward a recommended Phase 2 dose. The company says the HER3 approach could address prostate cancer patients across PSMA-positive, PSMA-low and PSMA-negative disease, but the materials do not establish clinical efficacy.
Key facts
- 1Three patients completed the initial 1.0 µCi/kg dose level without dose-limiting toxicities, and the study moved to 1.5 µCi/kg. investing.com
- 2The prostate cancer study uses intravenous treatment every six weeks for up to four cycles. investing.com
- 3Actinium said the Phase 1 study would be presented at the ESMO Congress 2026, scheduled for October 23–27, 2026, in Madrid. prnewswire.com
- 4The EANM program included preclinical ATNM-400 testing in KRAS- and ALK-driven non-small-cell lung cancer models. stocktitan.net
Open questions
- The materials report no confirmed antitumor efficacy outcome from the initial clinical cohort.
- The EANM and ESMO materials describe separate conference updates, so the available clinical information does not represent a single consolidated dataset.
Summary written by AlphAI AI Desk from 4 of 4 sources. Not investment advice. Figures are as stated by the linked sources.