Welcome to our dedicated page for Actinium Pharmac news (Ticker: ATNM), a resource for investors and traders seeking the latest updates and insights on Actinium Pharmac stock.
Actinium Pharmaceuticals develops targeted radiotherapies for cancer using its Antibody Radiation Conjugates platform and alpha-emitting radioisotopes. Company updates commonly focus on ATNM-400, an Actinium-225 antibody radioconjugate studied in solid tumor models including prostate, lung, and breast cancer, and Actimab-A, or lintuzumab-Ac225, an Actinium-225 therapy targeting CD33 in acute myeloid leukemia.
Additional announcements describe radiochemistry work such as chelator-to-antibody ratio optimization, preclinical data presented at oncology and nuclear medicine meetings, and the company's broader radiotherapy platform across solid tumors, hematologic malignancies, and conditioning for cellular therapies.
Actinium (NYSE American: ATNM) reported new preclinical data for ATNM-400 in non-small cell lung cancer at SNMMI 2026. ATNM-400 outperformed KRAS inhibitors sotorasib and adagrasib in models and showed strong synergy with EGFR inhibitor osimertinib, achieving complete tumor regression in combination.
ATNM-400’s target is expressed in about 98% of NSCLC tumors and can increase 3.5–3.8x after KRAS inhibitor treatment. According to Actinium, this supports a potential mutation-agnostic backbone role across large EGFR- and KRAS-mutant NSCLC segments.
Actinium Pharmaceuticals (NYSE American: ATNM) presented new preclinical data on ATNM-400 at SNMMI 2026 in prostate cancer models. ATNM-400 stayed active in tumors resistant to all three approved androgen receptor inhibitors, achieved up to 94% tumor growth inhibition as monotherapy and 107% in combinations, and showed flexible, well-tolerated single and repeat dosing.
ATNM-400 matched or exceeded PSMA-targeted radioligands across PSMA expression levels, while its non-PSMA target is not expressed in salivary glands, so xerostomia is not expected. Actinium highlights a potential addressable population of over 100,000 mCRPC patients annually across ARPI-resistant and PSMA-ineligible segments.
Actinium (NYSE American: ATNM) appointed Steffen Heeger MD, MSc as Chief Medical Officer to guide its targeted radiotherapy pipeline. Heeger has led oncology programs from IND to global approvals, including work on Erbitux®, PSMA radiotherapies, and multiple hematologic and solid tumor assets.
According to Actinium, his experience aligns with advancing Actimab-A, ATNM-400, and Iomab-ACT toward key data readouts and expanded clinical trials in 2H 2026.
Actinium Pharmaceuticals (NYSE American: ATNM) presented new radiochemistry data at SNMMI 2026 on May 31, 2026, showing that optimizing chelator-to-antibody ratio (CAR) for Actinium-225 radioconjugates affects radiolabeling, antigen binding, internalization, and biodistribution.
Lower-CAR constructs maintained tumor uptake while reducing liver and spleen exposure, potentially widening the therapeutic index across Actinium’s radioconjugate pipeline.
Actinium Pharmaceuticals (NYSE American: ATNM) received two Canadian patent allowances covering its Actimab-A and Iomab-ACT programs. These patents extend protection for Actimab-A plus CLAG-M in AML and CD45-targeted conditioning for gene-edited cell therapies, reinforcing a global estate of about 250 patents and applications, with Canadian terms into 2038 and 2039.
Actinium Pharmaceuticals (NYSE American: ATNM) will present new ATNM-400 Actinium-225 antibody radioconjugate data at the SNMMI 2026 meeting in Los Angeles through three scientific posters covering prostate cancer, non-small cell lung cancer and radioconjugate optimization.
The company also received an NYSE American notice for not meeting certain stockholders’ equity listing standards and must submit a compliance plan by June 26, 2026, to avoid potential delisting actions by November 27, 2027.
Actinium (NYSE: ATNM) announced three abstracts at SNMMI 2026 (May 30–June 2, Los Angeles) presenting preclinical data for ATNM-400 and radiochemistry optimization. The posters report ATNM-400 activity in KRAS-mutated NSCLC and PSMA-high/low/negative prostate cancer models and CAR optimization for 225Ac radioconjugates.
Actinium Pharmaceuticals (NYSE: ATNM) presented preclinical AACR 2026 data showing ATNM-400, an Ac-225 radioconjugate, with pan-tumor activity in prostate, EGFR-mutant lung, and HER2+ breast cancer models.
Data show efficacy in low/negative PSMA prostate models, superior activity versus several approved ADCs and targeted agents, durable control post-treatment in breast models, and no in vivo toxicities at therapeutic doses.
Actinium (NYSE:ATNM) presented AACR 2026 data showing that Actimab-A (lintuzumab-Ac225) drives mutation-agnostic anti-leukemic activity via transcriptional reprogramming, shifting AML cells from proliferation toward differentiation and apoptosis. Combinations with revumenib, gilteritinib, and azacitidine enhanced in vivo killing across models and primary patient samples, independent of FLT3, NPM1, KMT2A, IDH1/2, or TP53 status. Prior clinical work in >150 AML patients showed a manageable safety profile and supports Actimab-A as a universal combination backbone across AML treatment settings.
Actinium Pharmaceuticals (NYSE: ATNM) announced two AACR 2026 abstracts to be presented April 21, 2026, highlighting new preclinical data for ATNM-400 and a differentiated mechanism for Actimab-A. ATNM-400 shows pan-tumor Ac-225 radioconjugate activity; Actimab-A shows mutation-agnostic transcriptional reprogramming that may enhance AML therapy response. Posters: ATNM-400 #5824 and Actimab-A #5827 in session Radiopharmaceutical Platforms for Theranostic Precision Oncology, April 21, 2:00–5:00 PM PT, Poster Section 16.