Actinium Pharmaceuticals will present new preclinical data for its lead radiotherapy candidate ATNM‑400 at the San Antonio Breast Cancer Symposium (SABCS) on Thursday, December 11, 2025, from 5:00 PM to 6:30 PM Central Time. The presentation will focus on hormone‑receptor positive, HER2‑positive, and triple‑negative breast cancer models, including models resistant to tamoxifen and trastuzumab. ATNM‑400 targets a non‑PSMA antigen that remains overexpressed in breast cancer cells even after resistance develops, and it delivers alpha‑particle radiation via Actinium‑225 to achieve potent tumor killing while limiting off‑target toxicity such as interstitial lung disease.
The preclinical studies also demonstrate tumor regression in metastatic castration‑resistant prostate cancer and non‑small cell lung cancer, underscoring ATNM‑400’s pan‑tumor potential. By presenting at SABCS, Actinium aims to engage a broad oncology audience, attract potential collaborators, and lay the groundwork for future clinical development of the candidate.
This presentation marks a strategic pivot for Actinium, which is shifting focus from its earlier Iomab‑B program to ATNM‑400 after the FDA requested an additional head‑to‑head trial for Iomab‑B. The company’s limited runway and need for financing make the upcoming presentation a critical milestone for securing partnerships or additional capital.
Actinium’s financials for the third quarter ended September 30, 2025, show a net loss of $5.1 million on revenue of $90 k, an improvement from the $11.57 million loss a year earlier. For the nine months ended September 30, the company reported a net loss of $27.95 million versus $31.59 million in the prior year, while cash and cash equivalents stood at $53.4 million. These figures highlight the company’s ongoing need for funding to advance ATNM‑400 into clinical trials.
CEO Sandesh Seth emphasized the significance of the preclinical data, stating that the results “underscore ATNM‑400’s potential to transform outcomes for breast cancer patients who have limited therapeutic options after developing resistance to endocrine or HER2‑targeted therapies and those with triple‑negative disease.” The company’s focus on ATNM‑400 reflects a broader strategy to develop a radiotherapeutic platform with broad applicability across multiple tumor types.
Analysts have noted the company’s strong buy consensus, and the upcoming SABCS presentation is expected to further elevate investor interest. The event is anticipated to provide a clearer view of ATNM‑400’s clinical development trajectory and potential partnership opportunities.
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