$ATNM News

Actinium (ATNM) grants options and RSUs to new CFO and SVP Biz Dev

Actinium hired Matt David as CFO and Sean Maenpaa as SVP Business Development and granted inducement equity: David received a 10‑year option for 250,000 shares at $0.97 plus 250,000 RSUs and up to 75,000 milestone RSUs; Maenpaa received a 10‑year option for 40,000 shares at $1.06 plus 20,000 RSUs and 50,000 milestone RSUs. Options vest 28% after one year then in 2% monthly installments over the next 36 months; awards were granted outside the company’s 2019 Stock Plan as NYSE inducements, creating potential dilution if all awards vest/exercised while tying pay to retention and corporate milestones.

ATNM-400 shows broad preclinical activity in NSCLC, colorectal and ovarian models; data to be presented at EANM

Actinium (ATNM) will present preclinical EANM 2026 data showing its Actinium-225 radioconjugate ATNM-400 produced antitumor activity across KRAS- and ALK-driven NSCLC (including resistant models), improved responses in colorectal xenografts when combined with bevacizumab+oxaliplatin, and durable single-agent activity in ovarian models including bevacizumab-refractory tumors. These are preclinical xenograft results that the company says support a mutation-agnostic, pan‑tumor development strategy and both monotherapy and combination approaches, but no clinical efficacy or safety data were reported yet.

Actinium (ATNM) hires radiopharma BD veteran Sean Maenpaa as SVP, Business Development

Actinium (ATNM) appointed Sean Maenpaa as SVP, Business Development effective Oct 12, 2026, tasking him with leading partnering, licensing, in‑licensing and corporate development across its targeted radiotherapy pipeline. Maenpaa brings 20+ years of oncology BD and commercial experience across radiopharmaceuticals, isotope supply and alpha/beta therapies (roles at Bayer, Clovis, Telix, BWXT, Novartis) and a track record that includes helping drive ILLUCCIX sales to $320M and orchestrating prior asset deals, signaling the company is positioning to pursue partnerships or out‑licensing to unlock pipeline value.

Actinium to present first‑in‑human Phase 1 data for ATNM‑400 (non‑PSMA Ac‑225 radiotherapy) at EANM

Actinium will orally present early results from the first‑in‑human Phase 1 dose‑escalation trial of ATNM‑400 at EANM 2026, showing Zr‑89 PET theranostic data used to characterize safety, biodistribution and dosimetry to inform Actinium‑225 therapeutic dosing. ATNM‑400 is a non‑PSMA targeted antibody radioconjugate intended to address PSMA‑low/negative and PSMA‑refractory mCRPC, but the company disclosed no specific efficacy or safety outcomes yet and the data are described as early.

Actinium Pharmaceuticals Strengthens Leadership Team with Appointment of Matt David, M.D. as Chief Financial Officer

Actinium adds Actimab‐A patents, expands manufacturing and gets NYSE compliance extension

Actinium (ATNM) announced multiple new patents expanding Actimab‐A IP—including US patents for targeting tumor‐resident MDSCs in solid tumors and issued/pending patents for AML and combination uses—and said it amended its IND to add an additional manufacturer to expand capacity ahead of clinical milestones expected Q4 2026 into 2027. NYSE Regulation accepted the company's compliance plan and granted the maximum cure period through November 27, 2027, keeping ATNM listed while the company works to meet listing standards.

ATNM-400 drives regressions and combo cures in preclinical KRAS/EGFR NSCLC models

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.

Actinium's ATNM-400 shows preclinical tumor regressions in KRAS/EGFR NSCLC and synergy with approved inhibitors

Actinium presented preclinical SNMMI data showing ATNM-400 produced tumor regressions in KRAS-mutant models and achieved complete tumor cures in an EGFR-mutant mouse model when combined with osimertinib. KRAS inhibitors sotorasib and adagrasib increased ATNM-400's target expression up to ~3.5–3.8x and combinations deepened tumor-cell killing, supporting a mutation-agnostic development strategy given the target is reported in ~98% of NSCLC tumors. These are preclinical cell-line and animal results only, so clinical efficacy and safety in humans remain unproven.

ATNM-400 active in ARPI‐resistant prostate cancer models; flexible dosing and favorable safety shown

Actinium presented preclinical SNMMI data showing ATNM-400, a non‐PSMA Ac‐225 antibody radioconjugate, remains potent in cells and tumors resistant to all three approved ARPIs (enzalutamide, apalutamide, darolutamide), achieving 94% tumor growth inhibition as a single agent (vs ~32% and 5% for apalutamide and darolutamide) and producing durable complete responses in combination in ≥57% of mice (4/7 and 5/7) in an ARPI‐resistant 22Rv1 model. The agent matched or exceeded PSMA‐targeted radioligands across PSMA‐high/low/negative models (comparable to 225Ac‐PSMA‐617 and superior to 177Lu‐PSMA‐617 at much lower administered activity), showed consistent tolerability across single‐bolus and repeat dosing with minimal blood/liver/kidney signals, and—because its target is not expressed in salivary glands—is not expected to cause xerostomia; clinical benefit remains unproven as these are preclinical results.