ATNM 10-K & 10-Q changes, risk factors and insider trading

We have incurred net losses in every year since our inception and anticipate that we will continue to incur net losses in the future.

We are highly dependent on the clinical, regulatory and commercial success of ATNM-400, Actimab-A, Iomab-ACTIomab-ACT, ATNM-400 and other pipeline candidates candidates which we may never achieve

None of the drug candidates we are developing, or have developed, have received regulatory approval. Based on the current status of our pipeline candidates, it will likely take several years orand additional clinical studies before we can seek approval for any drug candidate.

ATNM-400 is currently being studied preclinically and has not yet been studied in human subjects. There can be no assurances that we will advance ATNM-400 into clinical trials and even if we are successful in doing so, our preclinical results to date may not translate in connection with human subjects. Our Actimab-A drug candidate was studied in a Phase 2 clinical trial as a monotherapymonotherapy, and we are now studying it in combination with other therapies. We believe we have aligned with the FDA on an operationally seamlessa Phase 2/3 trial that is intended to support a BLA filing. There can be no assurance that the Phase 2 portion of the trial will be successful and support advancing to the Phase 3 portion of the trial. In addition, our Iomab-ACT drug candidate has only been studied in a limited number of human subjects in a Phase 1 trial with a novel CAR-T therapy. While we believe the initial results results from this trial were encouraging, there can be no assurance that future results with Iomab-ACT from the commercial CAR-T trial at UTSW or sickle cell conditioning trial at Columbia will be positive.

As for Iomab-B in particular, as previously disclosed, we completed the pivotal Phase 3 SIERRA trial (Study of Iomab-B in Elderly Relapsed or Refractory AML) and presented the trial results in February 2023, which were expected to support a BLA filing. The SIERRA trial met the primary endpoint of dCR with statistical significance (p-value<0.0001) but did not meet the secondary endpoint in achieving a statistically significant improvement in overall survivalOS in the intent to treat population. On August 5, 2024, we announced that the FDA determined that the SIERRA trial alone is not adequate to support a BLA filing and is requiring an additional randomized head-to-head clinical trial to demonstrate an overall survivalOS benefit in an intent to treat population. Further, the FDA is also requiring an additional dose optimization trial to calculate the dose of Iomab-B based on absorbed dose by the bone marrow, rather than the maximum tolerable dose of 24 Gy of radiation to the liver as was done in the SIERRA trial based on several interactions with the FDA prior to the start of the SIERRA trial. Based on this revised approach now required by the FDA, the safety and efficacy data generated from all Iomab-B studies, including the SIERRA trial, are inadequate to seek regulatory approval for Iomab-B, as dosing based on maximum tolerable dose of 24 Gy to the liver will lead to variable doses to the bone marrow (the target organ), result in underdosing or overdosing of patients and translate to a global patient safety risk. We are seeking a strategic partner for the U.S. in order to conduct the additional studies required by the FDA; however, we may not be successful in our efforts to find such a partner, or the trials and studies may not be successful. Further, there are no assurances that we can satisfy all of the FDA’s requests, and there could be additional regulatory hurdles that may result in either non-acceptance or non-approval of a future BLA filing. The U.S. commercial opportunity for Iomab-B may thus never be realized.

Additionally, a future pandemic may result in delays in receiving approvals from local and foreign regulatory authorities, delays in necessary interactions with IRB’s or Institutional Review Boards,IRB, local and foreign regulators, ethics committees and other important agencies and contractors due to limitations in employee resources or forced furlough of government employees.

For instance, as for Iomab-B, despite the Phase SIERRA 3 trial meeting the primary endpoint of durable Complete Remission (dCR) with statistical significance (p-value<0.0001), the FDA has determined that demonstrating an overall survivalOS benefit in a randomized head-to-head trial is required for a BLA filing. In addition, the FDA is also requiring that an additional dose optimization trial demonstrating safety and efficacy be completed to calculate the dose of Iomab-B based on absorbed dose by the bone marrow, rather than the maximum tolerable dose of 24 Gy of radiation to the liver as was done in the SIERRA trial based on several interactions we had with the FDA before starting the SIERRA trial. The head-to-head Phase 3 trial will evaluate allogeneic bone marrow transplant (BMT) using Iomab-B plus a reduced intensity conditioning regimen of fludarabine and total body irradiation (Flu/TBI) versus allogeneic BMT using reduced intensity conditioning comprised of cyclophosphamide plus Flu/TBI. This is different from the SIERRA trial, which allowed physician’s choice of salvage therapies and heterogenous conditioning regimens in the control arm. However, there are no assurances that the additional trials will be completed or successful or that we can satisfy all of the FDA’s requests. There could also be additional regulatory hurdles that may result in either non-acceptance or non-approval of a future BLA filing.

As previously disclosed and noted above, Actinium has licensed to Immedica the exclusive product rights for commercialization of Iomab-B in the Europe, Middle East, and North Africa (EUMENA) region. We are evaluating the impact of the FDA’s 2024 determination of the SIERRA trials results referred to above in the context of global regulatory submission for Iomab-B. At this time, filings for regulatory approval, obtaining regulatory approvals, and successful commercialization of Iomab-B in the EUMENA region and on a global basis are highly uncertain and may never be realized.

Our Actimab-A (lintuzumab-Ac-225) product candidate has also been studied in several Phase 1 and 2 trials under our sponsorship and investigator-initiated trials in patients with r/r AML and we plan to continue to study Actimab-A in clinical trials. Actimab-A is also being developed under a cooperative research and development agreement (CRADA) with the National Cancer Institute (NCI) and we expect clinical trials to be initiated that will study Actimab-A as a single agent or in combination with other therapies. Product candidates utilizing the lintuzumab antibody would require BLA approval before they can be marketed in the United States. We are in the early stages of evaluating other product candidates consisting of conjugates of Ac-225 with human or humanized antibodies for pre-clinical and clinical development in other types of cancer.cancer such as ATNM-400. The FDA may not approve these products for the indications that are necessary or desirable for successful commercialization. The FDA may fail to approve any IND, BLA or NDA we submit for new product candidates or for new intended uses or indications for approved products or future product candidates. Failure to obtain FDA approval for our products in the proposed indications would have a material adverse effect on our business prospects, financial condition and results of operations.

We have not demonstrated that any of our products are safe andor effective for any indication and will continue to expend substantial time and resources on clinical development before any of our current or future product candidates will be eligible for FDA approval, if ever.

In the United States, the FDA regulates pharmaceutical and biological product candidates under the Federal Food, Drug, and Cosmetic Act (“FDCA”) and the Public Health Service Act (“PHSA”), as well as their respective implementing regulations. Such products and product candidates are also subject to other federal, state, and local statutes and regulations. The process of obtaining regulatory approvals and the subsequent compliance with appropriate federal, state, local, and foreign statutes and regulations requires the expenditure of substantial time and financial resources. The process required by the FDA before a drug or biological product may be marketed in the United States generally involves the following:

Before testing any biological product candidate in humans, the product candidate enters the preclinical testing stage. Preclinical tests include laboratory evaluations of product chemistry, toxicity and formulation, as well as animal studies to assess the potential safety and activity of the product candidate. The conduct of the preclinical tests must comply with federal regulations and requirements including GLPs. The clinical trial sponsor must submit the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature and a proposed clinical protocol, to the FDA as part of the IND.IND application. Some preclinical testing may continue even after the IND application is submitted. The IND application automatically becomes effective 30 days after receipt by the FDA, unless the FDA raises concerns or questions regarding the proposed clinical trials and places the trial on a clinical hold within that 30-day time period. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. The FDA may also impose clinical holds on a biological product candidate at any time before or during clinical trials due to safety concerns or non-compliance. If the FDA imposes a clinical hold, trials may not recommence without FDA authorization and then only under terms authorized by the FDA. Accordingly, we cannot be sure that submission of an IND application will result in the FDA allowing clinical trials to begin or that, for those that have already commenced under an active IND,IND application, that issues will not arise that suspend or terminate such trials.

Clinical trials involve the administration of the biological product candidate to healthy volunteers or patients under the supervision of qualified investigators, generally physicians not employed by or under the trial sponsor’s control. Clinical trials are conducted under protocols detailing, among other things, the objectives of the clinical trial, dosing procedures, subject selection and exclusion criteria, and the parameters to be used to monitor subject safety, including stopping rules that assure a clinical trial will be stopped if certain adverse events should occur. Each protocol and any amendments to the protocol must be submitted to the FDA as part of the IND.IND application. Clinical trials must be conducted and monitored in accordance with the FDA’s regulations composing the GCP requirements, including the requirement that all research subjects provide informed consent. Further, each clinical trial must be reviewed and approved by an independent institutional review board, or IRB, at or servicing each institution at which the clinical trial will be conducted. An IRB is charged with protecting the welfare and rights of trial participants and considers such items as whether the risks to individuals participating in the clinical trials are minimized and are reasonable in relation to anticipated benefits. The IRB also approves the form and content of the informed consent that must be signed by each clinical trial subject or his or her legal representative and must monitor the clinical trial until completed. Human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

Notwithstanding the submission of relevant data and information, the FDA may ultimately decide that the BLA does not satisfy its regulatory criteria for approval and deny approval. Data obtained from clinical trials are not always conclusive and the FDA may interpret data differently than we interpret the same data. We cannot predict with any certainty if or when we might submit a BLA for regulatory approval for our product candidates or whether any such BLA will be approved by the FDA. Human clinical trials are very expensive and difficult to design and implement, in part because they are subject to rigorous regulatory requirements. For example, the FDA may not agree with our proposed endpoints for any clinical trial we propose, which may delay the commencement of our clinical trials. The clinical trial process is also lengthy and requires substantial timetime, effort and effort.expense.

Initiating and completing clinical trials necessary to support FDA approval of a BLA for Iomab-B,ATNM-400, Actimab-A, Iomab-ACT, Iomab-B, and other product candidates, is a time-consuming and expensive process, and the outcome is inherently uncertain. Moreover, the results of early clinical trials are not necessarily predictive of future results, and any product candidate we advance into clinical trials may not have favorable results in later clinical trials.

Preliminary, Interim, and “top-line” data from our preclinical studies and clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we may publicly disclose preliminary, interim, and top-line data from our clinical trials, which is based on a preliminary analysis of then-available data, and the results and related findings and conclusions are subject to change as more patient data become available or following a more comprehensive review of the data related to the particular study or trial. We may also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. Our clinical trials may be open label studies and certain of our clinical development and /or operations staff may review interim or preliminary safety or efficacy data during routine data collection, cleaning and analysis from time to time. Interim or preliminary results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results once additional data have been received and fully evaluated. Preliminary, interim or top-line data also remain subject to audit and verification procedures that may result in the final data being materially different from the top-line, interim or preliminary data we previously published. As a result, top-line, interim and preliminary data should be viewed with caution until the final data are available.

From time to time, we may also disclose interim data from our preclinical studies and clinical trials. Interim data from preclinical studies are not necessarily predictive of future success in clinical trials. Interim data from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Adverse differences between interim data and final data could significantly harm our business prospects. Further, disclosure of interim data by us or by our competitors could result in volatility in the price of our common stock.

OurEven if our preclinical studies or early clinical trials are favorable, later clinical trials may fail to demonstrate adequately the efficacy and safety of our product candidates, which would prevent or delay regulatory approval and commercialization.

Even if our preclinical studies are favorable and our clinical trials are completed as planned, we cannot be certain that their results will support our product candidate claims or that the FDA or foreign authorities will agree with our conclusions regarding them. Success in pre-clinical studies and early clinical trials does not ensure that later clinical trials will be successful, and we cannot be sure that the later trials will replicate the results of prior trials and pre-clinical studies. The clinical trial process may fail to demonstrate that our product candidates are safe and effective for the proposed indicated uses. If the FDA concludes that theany current or future clinical trials for ATNM-400, Actimab-A, Iomab-ACT, Iomab-B or any other product candidate for which we might seek approval, have failed to demonstrate safety and effectiveness, we would not receive FDA approval to market that product candidate in the United States for the indications sought. In addition, such an outcome could cause us to abandon the product candidate and might delay the development of others. Any delay or termination of our clinical trials will delay or preclude the filing of any submissions with the FDA and, ultimately, our ability to commercialize our product candidates and generate revenues. It is also possible that patients enrolled in clinical trials will experience adverse side effects that are not currently part of a product candidate’s profile.

The intellectual property related to certain antibodies we have licensed has expired or likely expired.

The key patents related to the humanized antibody,antibody lintuzumab, which we use in our Actimab-A product candidatecandidate, have expired. It is generally possible that others may be eventually able to use an antibody with the same sequence, and we will then need to rely on additional patent protection covering alpha particle drug products comprising Ac-225. Our final drug construct, Actimab-A, consists of the lintuzumab antibody labeled with the isotope Ac-225. We currently own issued and pending patents relating to methods of manufacturing Actimab-A, methods of treatment using Actimab-A and production of the Ac-225 isotope. In addition, we possess trade secrets and know how related to the manufacturing and use of isotopes. Any competing product based on the lintuzumab antibody is likely to require several years of development before achieving our product candidate’s current status and may be subject to significant regulatory hurdleshurdles, but such development by others is nevertheless a possibility that could negatively impact our business in the future. We own 4 issued U.S. patents, 2 issued Canadian patents, 12 issued European patent (each validated as a national patent in several countries) and 1 issued Japanese patent that relate relate to the composition of our Iomab-B product candidate. Patent applications relating to Iomab-B are also pending in the U.S. and internationally. internationally. We have and may continue to file patents related to Iomab-B that can provide barriers to entry but there is no certainty that these patents will be granted or such granting thereof will adequately prevent others from seeking to replicate and use the apamistamab antibody or the construct. Our patent portfolio includes pending applications related to radioimmunoconjugate composition, formulation administration, administration, and methods of use in treating solid or liquid cancers. This subject matter includes composition, administration, and methods of treatment for our product candidates Actimab-A and Iomab-B. Any competing product based on the antibody used in Iomab-B is likely to require several years of development before achieving our product candidate’s current status and may be subject to significant regulatory hurdles. Further, if approved, Iomab-B would be entitled to 12 years of market exclusivity in the U.S. and 10 years in Europe, during which time no generic biologic or biosimilar product referencing Iomab-B can be granted marketing approval.

Our Actimab-A program is comprised of several clinical trials conducted under the CRADA with NCI, Actinium sponsored trials, investigator-initiated trials in AML and other myeloid indications and solid tumors that will study the same drug construct consisting of lintuzumab-Ac-225. Negative Negative results from any of these trials could negativelyadversely impact our ability to enroll or complete our other trials studying lintzumab-Ac-225, including future studies conducted under our CRADA with the NCI. Additionally, negative outcomes including safety concerns, may result in the FDA requiring amendment to certain clinical trials, placing a clinical hold on certain or all clinical trials or discontinuing other trials utilizing lintuzumab-Ac-225.

Actinium-225 is a key component of our Actimab-A product candidate, technology platform, preclinical R&D programs including ATNM-400 and other drug candidates that we might consider for development with the Ac-225 payload. We have secured multiple suppliers that are expected to provide cGMP Ac-225 for our planned clinical trials. There are adequate quantities of Ac-225 available today to meet our current needs via our present supplier, the Department of Energy (“DOE”), who has been our primary supplier of Ac-225 historically. The Ac-225 currently supplied for our clinical trials from the DOE is derived from the natural decay of thorium-229 from so-called ‘thorium-cows’ and is able to produce sufficient quantities that are several multiples of the amount of Ac-225 we require to supply our clinical programs through to the early commercialization phase. The DOE is also producing Ac-225 from a recently developed alternative route for Ac-225 production via a linear accelerator that is currently being evaluated by us. Initial preclinical and modelling results have indicated that the linear accelerator sourced Ac-225 does not impact labelling efficiency and expected distribution. In accordance with representations made by the DOE, the capacity of Ac-225 from this route is expected to be sufficient to supply all of Actinium’s pipeline and commercial Ac-225 needs and support new program expansion by not just Actinium but also other companies that are developing Ac-225 based products. Additional routes of Ac-225 production are being pursued by the DOE including the generation of new thorium cows and production via a cyclotron. The cyclotron production method for Ac-225 production leverages Actinium’s proprietary technology and know-how and presents an additional path towards production of high-quality Ac-225 at a scale that would be able to satisfy commercial needs. In addition, we are aware of at least ten other government and non-government entities globally including the U.S., Canada, Russia, Belgium, France and Japan that have, or expect to havehave, ability to supply Ac-225 or equipment for its production within the timeframes relevant to the potential first commercial approval of our Ac-225-based drug candidate.

There can be no assurance that the data generated in our clinical trials will be acceptable to the FDA or that if future modifications during the the trial are necessary, that any such modifications will be acceptable to the FDA. Certain modifications to a clinical trial protocol made during the course of the clinical trial have to be submitted to the FDA. This could result in the delay or halt of a clinical trial while the modification is evaluated. In addition, depending on the quantity and nature of the changes made, the FDA could take the position that some or all of the data generated by the clinical trial is not usable because the same protocol was not used throughout the trial. This might require the enrollment of additional subjects, which could result in the extension of the clinical trial and the FDA delaying approval approval of a product candidate. If the FDA believes that its prior approval is required for a particular modification, it can delay or halt a clinical trial while it evaluates additional information regarding the change.

We have obtained orphan drug designation from the FDA for two of our current product candidates and intend to pursue such designation for other other candidates and indications in the future, but we may be unable to obtain such designations or to maintain the benefits associated with with any orphan drug designations we have received or may receive in the future.

Healthcare legislative reform measures intended to increase pressure to reduce prices of pharmaceutical products paid for by Medicare or, otherwise, affect the federal regulation of the U.S. healthcare system could have a material adverse effect on our business, future revenue, if any, and and results of operations.

In the United States, there have been a number of legislative and regulatory initiatives focused on containing the cost of healthcare. The Affordable Care Act, for example, substantially changed the way healthcare is financed by both governmental and private insurers. The Affordable Care Act contains a number of provisions that could impact our business and operations, primarily, once we obtain FDA approval to commercialize one of our product candidates in the United States, if ever,ever. andThe Affordable Care Act may also affect our operations in ways we cannot currently predict. Affordable Care Act provisions that may affect our business include, among others, those governing enrollment in federal healthcare programs, reimbursement changes, rules regarding prescription drug benefits under health insurance exchanges, expansion of the 340B program, expansion of state Medicaid programs, fees and increased discount and rebate obligations, transparency and reporting requirements, and fraud and abuse enforcement. Such changes may impact existing government healthcare programs, industry competition, formulary composition, and may result in the development of new programs, including Medicare payment for performance initiatives, health technology assessments, and improvements to the physician quality reporting system and feedback program.

There have been significant judicial, administrative, executive, and legislative initiatives to modify, limit, replace, or repeal the Affordable Care Act since its enactment. For example, during his first term, former President Trump issued several Executive Orders and other directives designed to delay the implementation of certain provisions of the Affordable Care Act or otherwise circumvent some of the requirements for health insurance mandated by the Affordable Care Act. Concurrently, Congress considered legislation that would repeal or replace all or part of the Affordable Care Act. While Congress has not passed comprehensive repeal legislation, several bills affecting the implementation of the Affordable Care Act have been passed. For example, the Tax Cuts and Jobs Act of 2017 eliminated the Affordable Care Act provision requiring individuals to purchase and maintain health coverage, or the “individual mandate,” by reducing the associated penalty to zero, beginning in 2019. In December 2018, a district court in Texas held that the individual mandate is unconstitutional and that the rest of the Affordable Care Act is, therefore, invalid. On appeal, the Fifth Circuit Court of Appeals affirmed the holding on the individual mandate but remanded the case back to the lower court to reassess whether and how such holding affects the validity of the rest of the Affordable Care Act. The Fifth Circuit’s decision on the individual mandate was appealed to the U.S. Supreme Court. On June 17, 2021, the Supreme Court held that the plaintiffs (comprised of the state of Texas, as well as numerous other states and certain individuals) did not have standing to challenge the constitutionality of the Affordable Care Act’s individual mandate and, accordingly, vacated the Fifth Circuit’s decision and instructed the district court to dismiss the case. As a result, the Affordable Care Act remained in effect in its then-current form; however, we cannot predict what additional challenges may arise in the future, the outcome thereof, or the impact any such actions may have on our business. This uncertainty has become even greater given the new Trump administration and its proposed agenda.

The Biden administration also introduced various measures in 2021 focusing on healthcare and drug pricing, in particular. For example, on January 28, 2021, former President Biden issued an executive order that initiated a special enrollment period for purposes of obtaining health insurance coverage through the Affordable Care Act marketplace, which began on February 15, 2021, and remained open through August 15, 2021. The executive order also instructed certain governmental agencies to review and reconsider their existing policies and rules that limit access to healthcare, including among others, reexamining Medicaid demonstration projects and waiver programs that include work requirements and policies that create unnecessary barriers to obtaining access to health insurance coverage through Medicaid or the Affordable Care Act. On the legislative front, the American Rescue Plan Act of 2021 was signed into law on March 11, 2021, which, in relevant part, eliminates the statutory Medicaid drug rebate cap, currently set at 100% of a drug’s average manufacturer price, for single source drugs and innovator multiple source drugs, which began on January 1, 2024. And, in July 2021, the Biden administration released an executive order entitled, “Promoting Competition in the American Economy,” with multiple provisions aimed at prescription drugs. In response, on September 9, 2021, the Department of Health and Human Services (“HHS ”) released a “Comprehensive Plan for Addressing High Drug Prices” that outlines principles for drug pricing reform and sets out a variety of potential legislative policies that Congress could pursue as well as potential administrative actions HHS can take to advance these principles.

Our business and research efforts rely, in part, on funding and support from U.S. government agencies such as the NationalNIH, Institutes of Health (“NIH”), National Cancer Institute (“NCI”) and the Department of Health and Human Services (“HHS”).HHS. Government funding funding for these programs is subject to annual budgetary decisions, which can be unpredictable and influenced by shifting political and economic priorities. Reductions in government support for cancer research or other healthcare initiatives could limit grants, contracts, or other financial resources that we or our research collaborators depend on, potentially delaying our clinical programs and increasing our reliance on alternative funding sources. ForFrom instance,October 1, 2025 until November 12, 2025, the U.S federal government was shutdown, which curtailed operations of key agencies such as the FDA and the NIH. The NCI, with whom we have a CRADA with the NCI for the development of Actimab-A.Actimab-A, was Whilenot weoperating have been informed thatduring the fundingshutdown. forAs a result, our ability to advance clinical development, obtain regulatory interactions/approvals, or secure government-funded grants may be delayed or disrupted by the federal government shutdown. For example, active and planned trials under our CRADA is notare expected to be impacted, there can be no assurances that this will remain the case and any reduction or elimination of funding can have a material adverse impact on our business.delayed.

Moreover, with the change in presidential administration that recently occurred in the United States, government spending programs have become even more difficult to predict and may be subject to greater risk. Considerable uncertainty exists regarding how future budget and program decisions will unfold, including the spending priorities of the new U.S. presidential administration and Congress and what challenges budget reductions may present for our industry generally or for our company. InFor particular,example, President Trump recently attempted to place a widespread freeze on most federal grants and loans. Any freezefreeze, onreduction, recission, change in eligibility or compliance requirements, or other actions affecting government support for our products, programs, or studies could significantly impair our research and development activities, business, and operations.

Disruptions at at the FDA, the SEC and other government agencies or comparable regulatory authorities caused by government shutdowns, funding shortages or global health concerns, in addition to substantial uncertainty regarding the new Administration’s initiatives and how these might impact the FDA, its implementation of laws, regulations, policies and guidance, and its personnel, could hinder government agencies’ ability to hire and retain key leadership and other personnel, or otherwise prevent new products and services from being developed or commercialized in a timely manner, or otherwise prevent those agencies from performing normal business functions on which our business operations rely, including timely reviews, which could negatively impact our business.

The ability of the FDA or comparable foreign regulatory authorities to review and approve new products can be affected by a variety of factors, including government shutdowns, which recently occurred from October 1, 2025 until November 12, 2025, budget and funding levels, ability to hire and retain key personnel and accept the payment of user fees, and statutory, regulatory, and policy changes that may otherwise affect the FDA’s or comparable foreign regulatory authorities’ ability to perform routine functions. In addition, government funding of the SEC and other government agencies or comparable foreign regulatory authorities on which our operations may rely, including those that fund research and development activities, is subject to the political process, which is inherently fluid and unpredictable. Future government shutdowns could impact our ability to access the public markets and obtain necessary capital in order to properly capitalize and continue to fund our operations.

With the change in the U.S. Presidential Administration in 2025, there is substantial uncertainty as to whether and how the new administration will seek to modify or revise the requirements and policies of the FDA and other regulatory agencies with jurisdiction over our product candidates. This uncertainty could present new challenges and/or opportunities as we navigate development of our product candidates. Some of these efforts have manifested to date in the form of personnel measures that could impact the FDA’s ability to hire and/or retain key personnel, which could result in delays or limitations on our ability to obtain guidance from the FDA on our product candidates in development and obtain the requisite regulatory approvals in the future. Moreover, the new Administration has proposed action to freeze or reduce the budget of the National Institutes of Health, or NIH, as related to its funding for medical research, which could decrease the ability of facilities that rely on NIH funding to enroll and conduct clinical trials or increase the costs to us of conducting clinical trials. There remains general uncertainty regarding future activities. The new Administration could issue or promulgate executive orders, regulations, policies or guidance that adversely affect us or create a more challenging or costly environment to pursue the development of new therapeutic products. Alternatively, state governments may attempt to address or react to changes at the federal level with changes to their own regulatory frameworks in a manner that is adverse to our operations. If we become negatively impacted by future governmental orders, regulations, policies or guidance as a result of the new Administration, there could be a material adverse effect on us and our business.

Third-party payors may not adequately reimburse customers for any product candidates that we may commercialize or promote,promote and may impose coverage restrictions or limitations such as prior authorizations and step edits that affect their use.

We are not aware of any existing or pending regulations or legislation that pertains to generic radiopharmaceutical products such as our targeted radiotherapy product candidates. Our ARC product candidates are regulated by the FDA as biologic products, and we intend to to seek approval for these products pursuant to the BLA pathway. The Biologics Price Competition and Innovation Act of 2009, or BPCIA, created created an abbreviated pathway for the approval of biosimilar and interchangeable biologic products. The abbreviated regulatory pathway establishes establishes legal authority for the FDA to review and approve biosimilar biologics, including the possible designation of a biosimilar as “interchangeable” based on its similarity to an existing brand product. Under the BPCIA, an application for a biosimilar product cannot be approved by the FDA until 12 years after the original branded product was approved under a BLA and in Europe a biosimilar product cannot be approved until 10 years after the original branded product was approved. The law is complex and as a result, its ultimate impact, implementation, and meaning are subject to uncertainty. Even if a biosimilar gets approved for one of the antibodies that we use, the final constructs of our drug candidates consist of an antibody, radioisotope and in some cases a linker and we are not aware of any regulations that would require us to provide the final constructs or components to third parties or potential competitors. Therefore, based on the current regulations, we do not believe that the final drug product of our candidates can be subject to competition from a biosimilar as outlined in BPCIA for at least 12 years in the U.S. and 10 years in the EU. We are aware that generic versions of certain radiopharmaceuticals utilizing peptides have been submitted to the FDA via the Abbreviated New Drug Application (“ANDA”) pathway, however, those products are not covered under the BPCIA and therefore that generic pathway is not applicable to Iomab-B or Actimab-A. We expect this would also apply to other biologic drug candidates we may seek to develop in the future based on the current provisions of the BPCIA. Additionally, the Inflation Reduction Act (“IRA”) that was enacted in August 2022, states that reimbursement by the Centers for Medicare& Medicaid Services (“CMS”) for high-expenditure single-source biologic drugs, which we expect Iomab-B and Actimab-A to be, can only be negotiated after at least 11 years following approval compared to 7 years for non-biologic drugs with negotiated prices taking effect two years after selection. Therefore, we currently believe that our antibody radiation conjugates (“ARCs”) are less likely than small molecules to face pricing pressure and negotiation from IRA. Further, a drug or biological product that has an orphan drug designation, which Iomab-B and Actimab-A both have, for only one rare disease or condition will be excluded from the IRA’s price negotiations requirements until such time the biological products has designations for more than one rare disease or condition, or if is approved for an indication that is not within that single designated rare disease or condition, unless such additional designation or such disqualifying approvals are withdrawn by the time CMS evaluates the drug for selection for negotiation. In August 2023, 10 initial drugs were identified with negotiated prices that expectedwent to takeinto effect startingJanuary in1, 2026. In 2027 and 2028, it is expected that CMS will establish negotiated prices for 15 additional drugs in each respective year. We do not believe there is a high likelihood that Iomab-B or Actimab-A would be identified by CMS for negotiated pricing under IRA but there is potential that IRA and other additional state and federal healthcare reform measures will be adopted in the future and the implementation of cost-containment measures or other healthcare reforms may prevent us from being able to generate revenue, attain profitability or successfully commercialize our product candidates.

Actimab-A, Iomab-ACT, Iomab-ACT andATNM-400, Iomab-B and future product candidates that we may develop may never gain market acceptance among physicians, patients and the medical community. The degree of market acceptance of any of our products will depend on a number of factors, including the actual and perceived effectiveness and reliability of the product; the results of any long-term clinical trials relating to use of the product; the availability, relative cost and perceived advantages and disadvantages of alternative technologies; the degree to which treatments using the product are approved for reimbursement by public and private insurers; the strength of our marketing and distribution infrastructure; and the level of education and awareness among physicians and hospitals concerning the product.

Failure of Actimab-AActimab-A, orIomab-ACT, Iomab-ACT ATNM-400, Iomab-B or any of our other product candidates to significantly penetrate current or new markets would negatively impact our business financial condition and results of operations.

We may have conflicts with our partners, such as conflicts concerning the interpretation of preclinical or clinical data, pertaining to the global patient safety profile or efficacy results of our products, the achievement of milestones, the interpretation of contractual obligations, payments for services, development obligations or the ownership of intellectual property developed during our collaboration. We may seek to amend, modify or terminate agreements with partners, suppliers or service providers related to Iomab-B,ATNM-400, Actimab-A orActimab-A, Iomab-ACT or Iomab-B, but there can be no assurance that we can do so successfully or negotiate terms that are favorable to us. Failure of which can increase the risk of or result in litigation or alternative dispute resolution options taken against us. Further, we may exercise our decision-making authority under certain circumstances pertaining to global patient safety related to our products, which our partners may disagree with and may result in potential conflicts and public disclosure of our rationale and position. If any conflicts arise with any of our partners, such partner may act in a manner that is adverse to our best interests. Any such disagreement could result in one or more of the following, each of which could delay or prevent the development or commercialization of our product candidates, and in turn prevent us from generating revenues: unwillingness on the part of a partner to pay us milestone payments or royalties we believe are due under a collaboration; uncertainty regarding ownership of intellectual property rights arising from our collaborative activities, which could prevent us from entering into additional collaborations; unwillingness by the partner to cooperate in the development or manufacture of the product, including providing us with product data or materials; unwillingness on the part of a partner to keep us informed regarding the progress of its development and commercialization activities or to permit public disclosure of the results of those activities; initiating litigation or alternative dispute resolution options by either party to resolve the dispute; or attempts by either party to terminate the agreement. Litigation or alternative dispute resolution options can be lengthy and expensive, require significant time and attention from our management and are highly uncertain. There can be no assurance that if we pursue, or a partner pursues litigation or alternative dispute resolution options, that we will prevail. Monetary and equitable damages awarded against us could have a material adverse effect on our business.

As a result, our owned and licensed patents may not be valid,held invalid, and we may not be able to obtain and enforce patents and to maintain trade secret protection for the full commercial extent of our technology. The extent to which we are unable to do so could materially harm our business.

Our research, development and manufacturing activities involve the controlled use of hazardous materials, including chemicals, radioactive and biological materials, such as radioactive isotopes. We are subject to federal, state, local and foreign environmental laws and regulations governing, among other matters, the handling, transportation, storage, use and disposal of these materials and some waste products. Our radiopharmaceutical operations depend on NRC/Agreement State licenses, hazardous-materials shipping permissions, and third-party radioactive waste services; loss or disruption of any of these could halt clinical supply or commercialization. We cannot completely eliminate the risk of contamination or injury from these materials, and we could be held liable for any damages that result, which could exceed our financial resources. We currently maintain insurance coverage for injuries resulting from the hazardous materials we use; however, future claims may exceed the amount of our coverage. Also, we do not have insurance coverage for pollution cleanup and removal. Currently the costs of complying with such federal, state, local and foreign environmental regulations are not significant, and consist primarily of waste disposal expenses. However, they could become expensive, and current or future environmental laws or regulations may impair our research, development, production and commercialization efforts.

We continuously evaluate our business strategy and may modify our strategy as necessary to respond to developments in our business and other factors, and any such modification,modification such as a divestiture, spin-off, spin-out, merger or acquisition, if not successful, could have a material adverse effect on our business, financial condition, and results of operations.

The stock market is subject to significant price and volume fluctuations. In the past, following periods of volatility in the market price of a company’s securities, securities class action litigation has often been initiated against such a company. Litigation initiated against us, such as the matters further described under “Legal Proceedings”, whether or not successful, could result in substantial costs and diversion of our management’s attention and our resources, which could harm our business and financial condition.

We are subject to the information and reporting requirements of the Securities Exchange Act (the “Exchange Act”) and other federal securities laws, and the compliance obligations of the Sarbanes-Oxley Act. The costs of preparing and filing annual and quarterly reports and other information with the Securities and Exchange CommissionSEC and furnishing audited reports to stockholders are substantial. In addition, we will incur substantial expenses in connection with the preparation of registration statements and related documents with respect to any offerings of our common stock.

On April 7, 2022, we entered into a License Agreement with Immedica, (the License Agreement), pursuant to which Immedica licensed the exclusive product rights for commercialization of Iomab-B in certain countries in the EUMENA region. Upon signing, we were entitled to an upfront, non-refundable payment of $35.0 million from Immedica, which was received in May 2022. Under the terms of the License Agreement, we are eligible to receive certain regulatory and commercial milestone payments and royalties on net sales of the product in certain countries that may result from the License Agreement. We continue to retain commercialization rights in the U.S. and rest of the world.

Research and development expenses decreased by $8.6$8.9 million to $30.0$21.1 million for the year ended December 31, 2024,2025, compared to $38.7$30.0 million for the year ended December 31, 2023.2024. ThisThe decrease was primarily due to CMC expenses decliningdriven by $12.0a decline in outside CRO services and other preclinical R&D expenses of $5.5 million and consultinglower expensescompensation decliningof by $1.7$4.3 million due to lower CMCheadcount. activityIn relatedthe tosecond Iomab-B.quarter of 2025, we conducted a workforce optimization that reduced our headcount by approximately fourteen percent and announced a strategic pipeline prioritization. These declinesdecreases were partially offset by increasedhigher preclinicalnon-cash expensesstock-based compensation of $5.0$1.0 million.million, resulting from the cancellation of stock options described above.

Other income is comprised of net interest income in both reporting periods. Other income for the year ended December 31, 2025 was $2.4 million, a decrease of $1.5 million from $3.9 million for the year ended December 31, 2024 increased from $3.1 million for the year ended December 31, 20232024, primarily due to highera lower average interestcash rates.balance during 2025 compared to the prior year.

Net loss decreased by $10.6$4.4 million to $33.9 million for the year ended December 31, 2025, compared to $38.2 million for the year ended December 31, 2024, comparedprimarily due to $48.8lower research and development expenses of $8.9 million for the year ended December 31, 20232025. dueThis todecrease lowerwas researchpartially andoffset by development expenses, lowerhigher general and administrative expenses andof a$3.1 million, attributable to higher levelnon-cash stock-based compensation expense of $2.9 million resulting from the cancellation of stock options described above, along with lower other income.

Net cash used in operating activities for the year ended December 31, 20242025 was $33.1$24.6 million, representing a decrease of $14.2$8.5 million fromcompared to $47.3$33.1 million in the prior-year period,period. This reduction was primarily asdriven by lower cash compensation of $4.8 million due to reduced headcount and a result$5.5 million decline in outside CRO services and other preclinical R&D expenses, partially offset by lower interest income of a lower net loss of $10.8$1.5 million and a $1.0 million decrease in net operating assets and liabilities of $2.2 million.assets.

Net cash used in investingfinancing activities was $11 thousand and $153$217 thousand for the yearsyear ended December 31, 20242025 and December 31, 2023, respectively, primarily duerelated to restricted stock units withheld to cover tax withholding obligations. Net cash provided by financing activities of $29.3 million in 2024 was primarily from the purchasesale of equipmentshares forof ourcommon laboratory space.stock.

In August 2020, we entered into the Capital on Demand™ Sales Agreement with JonesTrading Institutional Services LLC, or JonesTrading, pursuant to which we are able to sell, from time to time, through or to JonesTrading, up to an aggregate of $200 million of our common stock. On June 28, 2022, we entered into an Amendment and Restated Capital on Demand™ Sales Agreement, or the Amended Sales Agreement, with JonesTrading and B. Riley Securities, Inc. (“B. Riley”). The Amended Sales Agreement modifies the original Capital on Demand™ Sales Agreement to include B. Riley as an additional sales agent thereunder. Shares of common stock were offered pursuant to a shelf registration statement on Form S-3 (File No. 333-242322) filed with the SEC on August 7, 2020 (the “Prior Shelf Registration Statement”). On August 11, 2023, we filed a registration statement on Form S-3 (File No. 333-273911), and amended on February 2, 2024, which was declared effective on February 5, 2024, to replace the Prior Shelf Registration Statement, including a base prospectus which covers the offering, issuance and sale of up to $500 million of common stock, preferred stock, warrants, units and/or subscription rights; and a sales agreement prospectus covering the offering, issuance and sale of up to a maximum aggregate offering price of $200 million of common stock that may be issued and sold under the Amended Sales Agreement. There was no sale of shares of common stock during the year ended December 31, 2025, pursuant to the Amended Sales Agreement. For the year ended December 31, 2024, we sold 3.5 million shares of common stock, resulting in gross proceeds of $29.9 million and net proceeds of $29.3 million.million Forunder the yearAmended ended DecemberSales 31, 2023, we sold 1.9 million shares of common stock, resulting in gross proceeds of $15.1 million and net proceeds of $14.6 million.Agreement.

We will require additional funds to conduct clinical and non-clinical trials, achieve regulatory approvals, and, subject to such approvals, commercially launch our product candidates, and will need to secure additional financing in the future to support our operations. As of the date of filing this report, we expect that our existing resources will be more than sufficient to fund our planned operations for more than 12 months following the date of this report. We base this belief on assumptions that are subject to change, and we may be required to use our available cash and cash equivalent resources sooner than we currently expect. OurIn the long-term, we intend to continue to fund our operations through the sales of our common stock and common stock equivalents, noting our actual future capital requirements will depend on many factors, including the progress and results of our ongoing clinical trials, the duration and cost of discovery and preclinical development, laboratory testing and clinical trials for our pipeline candidates, the timing and outcome of regulatory review of our product candidates, the costs involved in preparing, filing, prosecuting, maintaining, defending, and enforcing patent claims and other intellectual property rights, the number and development requirements of other pipeline candidates that we pursue, and the costs of commercialization activities, including product marketing, sales, and distribution.

Our management’s discussion and analysis of financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities in our consolidated financial statements during the reporting periods. These items are monitored and analyzed by us for changes in facts and circumstances, and material changes in these estimates could occur in the future. We base our estimates on historical experience, known trends and events, and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Changes in estimates are reflected in reported results for the period in which they become known. Actual results may differ materially from these estimates under different assumptions or conditions. The Company does not have any critical accounting estimates.estimates that are likely to have a material impact on our financial condition or results of operation.

In November 2024, FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40), to improve the disaggregation of expenses within the consolidated statement of operations. The amendments in ASU 2024-03 require disclosures in the notes to the consolidated financial statements and specified information about certain costs and expenses. The amendments require that at each interim and annual reporting period an entity disclose (a) employee compensation, (b) depreciation, and (c) intangible asset amortization included in each relevant expense caption; include certain amounts that are already required to be disclosed under current GAAP in the same disclosure as the other disaggregation requirements; and disclose a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated quantitatively. The amendments in ASU 2024-03 are effective January 1, 2027 and effective for interim periods beginning January 1, 2028.2028, either on a prospective or retrospective basis. We willare evaluate evaluating the impact of ASU 2024-03 on our financial statements.

Subsequent Events Event

We are not profitable and have incurred losses in each period since our inception. As of MarchJune 31,30, 2026 and December 31, 2025, we had an accumulated deficit of $415.2$387.3 million and $409.7 million, respectively. We reported net income of $22.4 million for the six months ended June 30, 2026 and a net loss of $5.5 million and $15.9$22.8 million for the threesix months ended MarchJune 31,30, 2026 and 2025, respectively.2025. We expect to continue to operate at a net loss as we continue our research and development efforts, continue to conduct clinical trials and develop manufacturing, sales, marketing and distribution capabilities. There can be no assurance that the products under development by us will be approved for sale in the United States or elsewhere. Furthermore, there can be no assurance that if such products are approved, they will be successfully commercialized, which would have an adverse effect on our business prospects, financial condition and results of operation.

We are a clinical-stage biopharmaceutical company pioneering the development of targeted radiotherapies to address significant unmet medical needs in oncology. We are focused on employing a biology-driven approach to develop differentiated, first-in-class radiopharmaceutical therapeutics for patients with solid tumors and hematologic malignancies. Our mission is to transform cancer treatment by delivering innovative, high-valuehigh-value, radioconjugates that maximize therapeutic efficacy while minimizing toxicity to healthy tissue by combining our deep understanding of tumor biology and translational medicine with our expertise in radiochemistry.

Since our inception, we have focused on developing innovative and differentiated radiotherapies. Our pipeline of both early and later stage development programs is a testimony to our approach in three areas with: (1) two novel solid tumor product candidates, ATNM-400 and Actimab-A, with pan-tumor potential, (2) Actimab-A, which is also being developed as a therapeutic backbone for acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in partnership with the National Cancer Institute (NCI), and (3) two targeted conditioning agents, Iomab-B for bone marrow transplant and Iomab-ACT for cell & gene therapies. Our solid tumor asset, ATNM-400, targets a novel antigen distinct from PSMA, with demonstrated preclinical activity across metastatic castration-resistant prostate cancer (mCRPC), non-small cell lung cancer (NSCLC), and breast cancer. Actimab-A,Actimab-A targets myeloid derived suppressor cells (MDSCs) and is being studied in multiple solid tumors in combination with immune checkpoint inhibitors where MDSCs are known to act as an efficacy deterrent for these agents. Our hematology franchise includes: Actimab-A, a CD33-targeted therapy; as well as, Iomab-B and Iomab-ACT which are CD45-targeting conditioning agents. Both Actimab-A and Iomab-B are Phase 2/3 ready assets and are supported by extensive validation in over 15 clinical trials in which more than 500 patients were treated. We have several ongoing clinical studies across our pipeline. We expect to report data from ongoing company- and investigator-sponsored clinical studies for ATNM-400, Actimab-A for MDSC’s and Iomab-ACT in 4Q:2026 and over the course of 2027.

ATNM-400 is our lead solid tumor program, representing a first-in-class Ac-225 antibody radioconjugate targeting a novel, undisclosed, non-PSMA targetingundisclosed antigen with expression across multiple solid tumor types. The ATNM-400 target is implicated in disease biology during tumor progression and is also overexpressed when tumors become resistant to many approved therapies in multiple solid tumors. We are developing ATNM-400 as a potential pan-cancer, biology-driven therapy - alone or in combination with standard-of-care agents - for large, treatment resistant-solid tumor populations across prostate, NSCLC, breast cancer and potentially other sizable cancer indications.

These preclinical translational data show that ATNM-400 works well as monotherapy but is even better in combination in resistant settings where the target is overexpressed as part of the resistance mechanism.mechanism of several of the approved standard-of-care drugs. Evidence of ATNM-400 target expression has been observed ranging from 60%-80%+ in of mCRPC, >90% of NSCLC, and 50-70% of breast cancer patient tumors, representing a significant addressable population of well over a hundred thousand patients in the United States based on our existing datasets. We believe this number may expand as we continue our work to demonstrate the potential of ATNM-400 in various additional disease and treatment settings.

ATNM-400 retained anti-tumor activity in prostate cancer models followingafter tumors had progressed on 177Lu-PSMA-617. Following tumor progression on 177Lu-PSMA-617, 177Lu-PSMA-617ATNM-400 andproduced enzalutamide.continued tumor growth inhibition, supporting its potential to treat patients who have exhausted PSMA-directed radioligand therapy.