Actinium Pharmaceuticals to Present ATNM-400 Program Update at SNMMI 2026 Conference on May 31-June 2 and Provides NYSE American Listing Standards Notice

Rhea-AI Summary

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.

AI-generated analysis. Not financial advice.

Positive

• ATNM-400 featured in three SNMMI 2026 scientific presentations
• NYSE American notice has no immediate effect on ATNM share listing
• Company can submit compliance plan by June 26, 2026 to address standards

Negative

• Stockholders’ equity $2.3 million vs. $4.0 million minimum requirement
• Net losses reported in last five fiscal years through December 31, 2025
• Non-compliance with NYSE American Sections 1003(a)(ii) and (iii)
• Risk of NYSE American delisting if compliance not regained by November 27, 2027

Key Figures

Stockholders’ equity: $2.3 million Equity requirement: $4.0 million Net loss: $33.9 million +5 more

8 metrics

Stockholders’ equity $2.3 million As of March 31, 2026; below NYSE American $4.0M requirement

Equity requirement $4.0 million NYSE American Section 1003(a)(ii) stockholders’ equity minimum

Net loss $33.9 million Full year 2025 net loss per 10-K

Accumulated deficit $409.7 million Cumulative deficit reported in 2025 10-K

Cash & equivalents $53.4 million As of September 30, 2025 per Q3 2025 10-Q

Deferred license revenue $35.0 million Long-term deferred revenue tied to EU milestones for Iomab-B

Stock-based compensation $8.8 million Expense in six months ended Q2 2025 related to option cancellations

Shares outstanding 31,374,994 Common shares outstanding as of March 30, 2026

Market Reality Check

Price: $1.2600 Vol: Volume 150,980 vs 20-day ...

normal vol

$1.2600 Last Close

Volume Volume 150,980 vs 20-day average 109,121, indicating elevated trading activity before this notice. normal

Technical Price $1.26 is trading below the 200-day MA of $1.36 and 35.23% below the 52-week high.

Peers on Argus

ATNM gained 9.57% with mixed peer moves: one notable gainer (GNTA +4.78%) and se...

ATNM gained 9.57% with mixed peer moves: one notable gainer (GNTA +4.78%) and several decliners (e.g., CUE -4.7%), pointing to a stock-specific reaction rather than a broad biotechnology move.

Historical Context

5 past events · Latest: May 06 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
May 06	Conference abstracts	Positive	-1.6%	Announced three SNMMI 2026 abstracts highlighting ATNM-400 and radiochemistry work.
Apr 22	Preclinical data update	Positive	-10.9%	Reported compelling pan-tumor ATNM-400 efficacy data at AACR 2026 across multiple cancers.
Apr 22	Mechanism of action data	Positive	-10.9%	Detailed mutation-agnostic Actimab-A activity and combinations in AML models at AACR 2026.
Apr 06	Upcoming AACR data	Positive	+11.2%	Previewed AACR abstracts with new ATNM-400 solid tumor data and Actimab-A mechanism work.
Feb 17	Conference preview	Positive	-2.7%	Announced two planned AACR 2026 abstracts on ATNM-400 and Actimab-A theranostic platforms.

Pattern Detected

Recent news has largely been positive on preclinical and pipeline progress, yet the stock more often traded lower on these updates, with only one notably positive price reaction.

Recent Company History

Over the last few months, Actinium has repeatedly highlighted its Ac‑225 radioconjugate platforms, especially ATNM‑400 across multiple solid tumor models and Actimab‑A in AML. Several AACR and SNMMI‑related announcements emphasized pan‑tumor activity and differentiated mechanisms, yet four of five prior news events with similar scientific focus were followed by negative or modestly negative price moves. Today’s update combines another ATNM‑400 data showcase with a NYSE American listing compliance notice, adding a new regulatory overhang to an R&D‑driven story.

Market Pulse Summary

This announcement combines positive scientific momentum for ATNM‑400 with a material listing complia...

Analysis

This announcement combines positive scientific momentum for ATNM‑400 with a material listing compliance risk. New SNMMI 2026 presentations reinforce mutation‑agnostic, pan‑tumor ambitions, while the NYSE American notice highlights stockholders’ equity of $2.3 million versus a required $4.0 million and a $33.9 million 2025 net loss. Investors may track the compliance plan due June 26, 2026, progress toward the November 27, 2027 deadline, cash levels, and how pipeline data evolve toward clinical milestones.

Key Terms

actinium-225, antibody radioconjugate, non-small cell lung cancer, chelator-to-antibody ratio, +4 more

8 terms

actinium-225 medical

"first-in-class Actinium-225 (225Ac) antibody radioconjugate, ATNM-400, highlighting new data"

Actinium-225 is a rare, radioactive form of the metal actinium used as a microscopic radiation source in some cancer treatments; it emits very strong, short-range radiation that can destroy diseased cells when attached to a carrier drug. Investors pay attention because supply is limited and production is complex, so shortages or cost changes can directly affect the development, manufacturing and valuation of companies pursuing therapies that rely on this scarce medical “fuel.”

antibody radioconjugate medical

"Actinium-225 (225Ac) antibody radioconjugate, ATNM-400, highlighting new data"

A antibody radioconjugate is a targeted medicine made by attaching a small radioactive particle to an antibody that seeks out specific cells, like a guided missile carrying a tiny radioactive warhead. For investors, it matters because this approach can deliver powerful effects to diseased tissue while sparing healthy cells, but it also brings complex manufacturing, safety and regulatory hurdles that can strongly influence clinical success, timelines and commercial value.

non-small cell lung cancer medical

"profile across prostate cancer and non-small cell lung cancer (NSCLC), while a third"

A broad category of lung tumors that grow from the cells lining the airways and make up the majority of lung cancer cases; it includes several subtypes that behave and respond to treatment differently, like different models of the same car family. It matters to investors because its large patient population and variety of treatment options — surgery, traditional chemo, targeted drugs and immunotherapies — create major markets where clinical trial results, drug approvals or changing treatment guidelines can quickly affect a company’s revenue and stock value.

chelator-to-antibody ratio technical

"Poster Title: Optimizing Chelator-to-Antibody Ratio Improves Tumor Targeting"

The chelator-to-antibody ratio (CAR) is the average number of small linking molecules attached to each antibody that hold a drug or radioactive payload. Think of the antibody as a carrier and the chelators as hooks that let it carry multiple “packages”; the CAR affects how potent the therapy is, how predictable and safe dosing will be, and how consistently it can be manufactured and regulated—factors that directly influence clinical success and investor risk.

pharmacokinetics medical

"Improves Tumor Targeting and Pharmacokinetics of 225Ac-Labeled Antibodies"

Pharmacokinetics is the study of how a substance, such as a drug or chemical, moves through and is processed by the body over time. It tracks how it is absorbed, distributed, broken down, and eventually eliminated. For investors, understanding pharmacokinetics helps gauge the effectiveness, safety, and potential risks of new medications or treatments, which can influence a company’s success and valuation in the healthcare industry.

stockholders' equity financial

"the Company reported stockholders' equity of approximately $2.3 million and had"

Stockholders' equity is the portion of a company's assets that belongs to its owners after all debts and obligations are paid; think of it as the value left for shareholders if the company sold everything and paid off what it owes. Investors watch it because it shows the company's net worth, indicates how much of growth is funded by owners versus debt, and helps assess financial health and the potential for future dividends or stock value increases — like the equity in a house after the mortgage is settled.

continued listing standards regulatory

"not in compliance with the continued listing standards set forth in Section 1003(a)(ii)"

Ongoing rules a stock exchange requires a listed company to meet to keep its shares trading publicly, such as minimum share price, market value, timely financial reports, and governance practices. Think of it as a membership checklist for a club: falling short can lead to warnings or removal from the exchange, which can sharply reduce liquidity, investor confidence, and a stock’s value. Investors watch these standards to gauge regulatory risk and the stability of their holdings.

delisting regulatory

"If the Company does not submit a plan or if the plan is not accepted, delisting proceedings"

Delisting occurs when a company's stock is removed from a stock exchange and is no longer available for trading there. This can happen voluntarily or because the company no longer meets the exchange's requirements. For investors, delisting means they can no longer buy or sell shares of that company on the exchange, which may make it more difficult to sell their investments or affect the stock's value.

AI-generated analysis. Not financial advice.

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NEW YORK, May 29, 2026 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a leader in the development of targeted radiotherapies, today announced it will provide a program update on its first-in-class Actinium-225 (225Ac) antibody radioconjugate, ATNM-400, highlighting new data that will be showcased across three presentations at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 Annual Meeting, taking place May 30-June 2, 2026, in Los Angeles, California. Two of the presentations showcase ATNM-400's differentiated profile across prostate cancer and non-small cell lung cancer (NSCLC), while a third demonstrates the importance of radioconjugate optimization for radiotherapies in the context of the Company's pipeline candidates.

With the SNMMI 2026 program now finalized, the Company is providing updated presentation details, including poster titles, presenters, dates, and times. The data to be presented reinforce the meaningful progress of the ATNM-400 program and its potential as a mutation-agnostic, pan-tumor therapy, while also demonstrating the strength of the underlying radioconjugate platform that supports Actinium's broader pipeline. The Company anticipates multiple catalysts for ATNM-400, Actimab-A and Iomab-ACT in 2H:2026 that are expected to demonstrate the clinical potential of these programs.

ATNM-400 SNMMI 2026 Presentation Details

Poster Title: ATNM-400: A First-in-Class Non-PSMA Actinium-225 Antibody Radioconjugate Demonstrates Superior Efficacy to PSMA-617 Radioligands and ARPIs With Favorable Safety Profile in Prostate Cancer Models
Presenter: Sumit Mukherjee Ph.D., Actinium Pharmaceuticals, Inc.
Session: Oncology: Discovery & Translational Meet the Author Session
Date & Time: Tuesday, June 2, 2026 11:30am-12:15pm PT | Los Angeles, California

Poster Title: ATNM-400: A First-in-Class Actinium-225 Antibody Radioconjugate Demonstrating Durable, Mutation-Agnostic Anti-Tumor Activity in Non-Small Cell Lung Cancer Models
Presenter: Shiva Kazerounian Ph.D., Actinium Pharmaceuticals, Inc.
Session: Oncology: Discovery & Translational Meet the Author Session
Date & Time: Tuesday, June 2, 2026, 11:30am-12:15pm PT | Los Angeles, California

Poster Title: Optimizing Chelator-to-Antibody Ratio Improves Tumor Targeting and Pharmacokinetics of 225Ac-Labeled Antibodies
Presenter: Shiva Kazerounian Ph.D., Actinium Pharmaceuticals, Inc.
Session: MTA05 RPSC/CMIIT POPs and Science Pavilion Mixer
Date & Time: Sunday, May 31, 2026, 7:30-8:00pm PT | Los Angeles, California

The posters will be available on the Company website shortly after the presentations at https://ir.actiniumpharma.com/presentations-webinars.

NYSE American Continued Listing Standards Notice
Actinium also announced today that it has received a notice (the "Notice") from the NYSE American LLC ("NYSE American") indicating that the Company is not in compliance with the continued listing standards set forth in Section 1003(a)(ii) of the NYSE American Company Guide (the "Company Guide"), which requires a listed company to maintain stockholders' equity of $4.0 million or more if it has reported losses from continuing operations and/or net losses in three of its four most recent fiscal years. As of March 31, 2026, the Company reported stockholders' equity of approximately $2.3 million and had net losses in its last five fiscal years ended December 31, 2025. The Notice also indicates that the Company is also not currently eligible for any exemption in Section 1003(a) of the Company Guide. The notice has no immediate effect on the listing or trading of the Company's common stock on the NYSE American and the Company's shares will continue to trade under the symbol "ATNM," subject to compliance with other listing requirements of the Company Guide.

In connection with the non-compliance with Sections 1003(a)(ii) and (iii) of the Company Guide, the Company must submit a compliance plan by June 26, 2026, advising of actions the Company has taken or will take to regain compliance with the continued listing standards by November 27, 2027 (the "Plan Period Deadline"). If the NYSE American determines to accept the plan, the Company will be notified in writing and will be subject to periodic reviews, including quarterly monitoring, for compliance with the plan.

If the Company does not submit a plan or if the plan is not accepted, delisting proceedings will commence. Furthermore, if the plan is accepted but the Company is not in compliance with the continued listing standards by the Plan Period Deadline which is eighteen months from the receipt of the notice or November 27, 2027, or if the Company does not make progress consistent with the plan during the plan period, Exchange staff will initiate delisting proceedings as appropriate. The Company may appeal a staff delisting determination in accordance with Section 1010 and Part 12 of the Company Guide.

Actinium currently intends to submit a plan to regain compliance within the required timeframe. There can be no assurance that the Company will be able to achieve compliance with the NYSE American's continued listing standards within the required timeframe of eighteen months from date of receipt of the notice or November 27, 2027.

About Actinium Pharmaceuticals, Inc.

Actinium is a pioneer in targeted radiotherapies designed to improve outcomes for patients with cancer. The company employs a biology-driven approach to develop differentiated radiopharmaceuticals for solid tumors and hematologic malignancies. Its mission is to transform cancer treatment through innovative radioconjugates that maximize therapeutic efficacy while minimizing toxicity to healthy tissue by combining expertise in tumor biology, translational medicine, and radiochemistry. Since inception, Actinium has focused on developing innovative radiotherapies. Its pipeline reflects this strategy across three areas: (1) solid tumor therapeutics including ATNM-400 and Actimab-A with pan-tumor potential; (2) Actimab-A as a therapeutic backbone for acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in collaboration with the National Cancer Institute (NCI); and (3) targeted conditioning agents including Iomab-B for bone marrow transplant and Iomab-ACT for cell and gene therapy conditioning. ATNM-400 targets a novel antigen distinct from PSMA and has demonstrated preclinical activity across metastatic castration-resistant prostate cancer (mCRPC), non-small cell lung cancer (NSCLC), and breast cancer. Actimab-A has shown improved survival in relapsed/refractory AML with CLAG-M and is advancing toward a Phase 2/3 trial, with additional development ongoing through a CRADA with the NCI. Actinium is also advancing preclinical solid tumor programs and holds ~250 patents and patent applications, including intellectual property related to cyclotron-based production of Ac-225. For more information, please visit www.actiniumpharma.com.

Forward-Looking Statements
This press release may contain projections or other "forward-looking statements" within the meaning of the "safe-harbor" provisions of the private securities litigation reform act of 1995 regarding future events or the future financial performance of the Company which the Company undertakes no obligation to update. These statements, including statements as related to regaining compliance with the rules of the NYSE American and submission of a compliance plan, are based on management's current expectations and are subject to risks and uncertainties that may cause actual results to differ materially from the anticipated or estimated future results, including the risks and uncertainties associated with preliminary study results varying from final results, estimates of potential markets for drugs under development, clinical trials, actions by the FDA and other governmental agencies, regulatory clearances, responses to regulatory matters, the market demand for and acceptance of Actinium's products and services, performance of clinical research organizations and other risks detailed from time to time in Actinium's filings with the Securities and Exchange Commission (the "SEC"), including without limitation its most recent annual report on form 10-K, subsequent quarterly reports on Forms 10-Q and Forms 8-K, each as amended and supplemented from time to time.

Investors: investorrelations@actiniumpharma.com

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SOURCE Actinium Pharmaceuticals, Inc.

FAQ

What did Actinium Pharmaceuticals (ATNM) announce on May 29, 2026 about SNMMI 2026?

Actinium Pharmaceuticals announced three ATNM-400 presentations at the SNMMI 2026 Annual Meeting. According to Actinium, these posters cover prostate cancer, non-small cell lung cancer models, and chelator-to-antibody ratio optimization for Actinium-225 radioconjugate therapies in its pipeline.

What is ATNM-400 in Actinium Pharmaceuticals’ (ATNM) oncology pipeline?

ATNM-400 is described as a first-in-class Actinium-225 antibody radioconjugate. According to Actinium, it shows activity in prostate cancer and non-small cell lung cancer models and is being positioned as a mutation-agnostic, pan-tumor therapy within its targeted radiotherapy platform.

Why did Actinium Pharmaceuticals (ATNM) receive an NYSE American continued listing standards notice?

Actinium received the notice for not meeting NYSE American stockholders’ equity requirements. According to Actinium, equity was about $2.3 million on March 31, 2026, below the $4.0 million threshold, with net losses in its last five fiscal years ended December 31, 2025.

Does the NYSE American notice immediately affect trading of Actinium Pharmaceuticals (ATNM) stock?

The notice does not immediately affect trading of ATNM shares. According to Actinium, its common stock will continue to trade on NYSE American under the symbol ATNM, provided the company remains compliant with other applicable listing requirements during the review period.

What deadlines does Actinium Pharmaceuticals (ATNM) face to regain NYSE American compliance?

Actinium must submit a compliance plan by June 26, 2026. According to Actinium, the company then has up to eighteen months, until around November 27, 2027, to regain compliance with NYSE American continued listing standards or face potential delisting proceedings.

How might the NYSE American compliance plan process impact Actinium Pharmaceuticals (ATNM) investors?

Investors face uncertainty until NYSE American rules on Actinium’s plan and progress. According to Actinium, failure to submit an acceptable plan or regain compliance by November 27, 2027 could trigger delisting proceedings, although the company may appeal any staff delisting determination.

What future catalysts does Actinium Pharmaceuticals (ATNM) expect for ATNM-400 and its pipeline?

Actinium expects multiple catalysts for ATNM-400, Actimab-A and Iomab-ACT in the second half of 2026. According to Actinium, these events are anticipated to further demonstrate the clinical potential of its targeted radiotherapy programs across different hematologic and solid tumor indications.