On June 3, 2026 Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a pioneer in the development of targeted radiotherapies, on June 2, 2026, reported new data on ATNM-400 in prostate cancer at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 Annual Meeting taking place in Los Angeles, California.

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Androgen receptor pathway inhibitors (ARPIs) such as enzalutamide (Xtandi, Astellas/Pfizer), apalutamide (Erleada, Johnson & Johnson), and darolutamide (Nubeqa, Bayer) are foundational to advanced prostate cancer care, but virtually all patients eventually develop resistance and progress -with up to 50,0001 patients per year exhausting ARPI therapy- creating a large and recurring unmet need. ATNM-400, Actinium’s first-in-class Actinium-225 antibody radioconjugate, targets a non-PSMA antigen linked to aggressive prostate cancer biology and delivers a high-energy alpha-particle payload that kills tumor cells through a mechanism independent of PSMA expression and androgen receptor signaling. In preclinical head-to-head studies, this PSMA-independent mechanism allowed ATNM-400 to match or exceed PSMA-targeted radioligand therapies, including 177Lu-PSMA-617 (active ingredient of Pluvicto, Novartis) and 225Ac-PSMA-617, across PSMA-high, PSMA-low, and PSMA-negative models.

The new data presented at SNMMI 2026 address three key questions: whether ATNM-400 can overcome ARPI resistance in the mCRPC setting, whether it works as both a single agent and in combination, and how its dosing and safety profile support translation to patients. The data answer each: ATNM-400 remained potent against cells and tumors resistant to all three approved ARPIs, achieved 94% tumor growth inhibition as a single agent and durable complete responses in combination, and maintained a consistent, clean safety profile across both single-bolus and repeat-dose regimens.

Prostate cancer is one of oncology’s largest commercial opportunities: androgen receptor pathway inhibitors generate more than $12 billion in annual sales in 2025 and Pluvicto (177Lu-PSMA-617) reached $2.0 billion in 2025, yet up to 50,0001 patients exhaust ARPI therapy each year and roughly 30% of mCRPC patients are ineligible for PSMA-directed therapy. Because ATNM-400 acts independently of both androgen receptor signaling and PSMA, it is positioned to serve the full mCRPC continuum, from patients who have failed ARPIs to the PSMA-low and PSMA-negative populations with no approved targeted radiotherapy today. Actinium estimates this represents a combined opportunity of more than 100,000 patients annually, addressable as a monotherapy or in combination with existing standards of care.

Sandesh Seth, Actinium’s Chairman and CEO, said, "ARPI resistance is a central problem in advanced prostate cancer as once these drugs stop working there are few good options left. The new data are compelling as ATNM-400 stayed potent in cells and tumors resistant to all three approved ARPIs, outperformed apalutamide and darolutamide on its own similar to previous data with enzalutamide, and produced durable complete responses when combined with them. Equally important for development, ATNM-400 worked across single-dose and repeat-dose regimens with a consistent, clean safety profile, giving us real flexibility as we move toward the clinic. We believe these findings position ATNM-400 as a differentiated option for patients who have run out of ARPI choices. The same resistance-targeting biology underlies the compelling activity we have reported in non-small cell lung cancer and breast cancer, positioning ATNM-400 as a potential pan-tumor backbone for large, resistance-driven patient populations, alone or in combination. We look forward to sharing additional data across these programs in the coming months as we advance ATNM-400 toward the clinic."

Highlights from the SNMMI 2026 Poster Presentation

Poster Titled: 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

New data presented at SNMMI 2026 highlight several findings central to ATNM-400’s development in prostate cancer:

In a low-PSMA, moderate-target tumor model (22Rv1), a single bolus dose of ATNM-400 (40 or 30 µCi/kg) delivered superior tumor control versus fractionated dosing, and a repeat 30 µCi/kg regimen sustained tumor control and survival through day 60 with all regimens outperforming 177Lu-PSMA-617 and showing minimal deviation from vehicle in blood, liver, and kidney safety markers. Flexible, well-tolerated dosing gives clinicians multiple ways to balance efficacy and safety and points to a wide therapeutic window.

ATNM-400 produced potent, dose-dependent killing of prostate cancer cells that are resistant to enzalutamide, apalutamide, and darolutamide, driving cell viability toward zero after each ARPI had failed, while the ARPIs alone left the resistant cells largely intact. Demonstrating activity specifically after ARPI failure addresses the most common point of progression in advanced prostate cancer and supports ATNM-400 as a treatment option for patients with few alternatives.

As monotherapy in an ARPI-resistant tumor model (22Rv1), ATNM-400 achieved 94% tumor growth inhibition versus just 32% for apalutamide and 5% for darolutamide, roughly three- to eighteen-fold greater tumor control than the ARPIs themselves. Working on its own in tumors that no longer respond to standard ARPIs positions ATNM-400 as a potential stand-alone therapy after resistance, not only an add-on.

In combination with either apalutamide or darolutamide in the same ARPI-resistant model, ATNM-400 delivered durable tumor control at 107% tumor growth inhibition, with complete responses in at least 57% of mice (4/7 and 5/7). Turning resistant tumors into complete responses by pairing ATNM-400 with the very drugs that had failed supports a combination strategy that could extend the commercial and clinical value of approved ARPIs.

In a high-PSMA, high-target tumor model (C4-2), ATNM-400 matched or exceeded both PSMA-targeted radioligands-comparable to 225Ac-PSMA-617 and superior to 177Lu-PSMA-617-while being given at roughly one-thousandth the administered radioactivity of 177Lu-PSMA-617 (40 µCi/kg versus 40 mCi/kg), with durable survival and favorable tolerability. Because ATNM-400 acts independently of PSMA, this activity carries across PSMA-high, PSMA-low, and PSMA-negative models, reaching the PSMA-variable patients that PSMA-directed radioligand therapy serve least well. Moreover as the ATNM-400 target is not expressed in the salivary glands xerostomia, a limitation of PSMA directed therapies and especially PSMA-Ac-225 based agents, is not expected.

(Press release, Actinium Pharmaceuticals, JUN 3, 2026, View Source [SID1234666411])

On June 3, 2026 Medicenna Therapeutics Corp. ("Medicenna" or the "Company") (TSX: MDNA, OTCQX: MDNAF), a clinical-stage immunotherapy company developing Superkines targeting cancer and autoimmune disease, reported that its long-acting, "beta-enhanced not-alpha" IL-2 Superkine, MDNA11, was featured in a poster presentation describing the investigator-sponsored NEO-CYT trial at the 2026 Annual Meeting of the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper), held in Chicago from 28th May to 2nd June.

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Surgery has long been the first course of action in treating locally advanced melanoma. Recently, the landmark NADINA clinical trial (comprised of 2 pre-operative cycles of ipilimumab plus nivolumab) completely flipped the conventional treatment paradigm on its head by proving that giving combination immunotherapy before surgery is significantly more effective than the previous post-surgery standard, setting a new gold standard of care. However even with this regimen, 41% of patients did not achieve a Major Pathologic Response (< 10% of viable tumor). In view of the promising single agent activity of MDNA11 in patients with metastatic melanoma, the hypothesis of the NEO-CYT trial is to demonstrate if patient outcomes can be further enhanced over the gold-standard of care by introducing MDNA11 in combination with nivolumab +/- ipilimumab.

"NEO-CYT provides an important opportunity to evaluate MDNA11, a potentially best-in-class IL-2 superagonist, in a frontline neoadjuvant setting where immune activation may be especially impactful," said Fahar Merchant, Ph.D., President and Chief Executive Officer of Medicenna. " If the tumor is still present at the time of the treatment, the immune cells ‘see’ more of the cancer cells. This allows the most potent anti-tumor immune cells to expand and attack the tumor and can remain active in the body for many years, preventing the tumors from recurring. Importantly, this trial complements our ongoing ABILITY-1 study, which has already demonstrated durable disease control in more advanced stages of melanoma. The ABILITY-1 trial is also advancing MDNA11 into earlier lines of therapy through expansion cohorts in 2L/3L melanoma, endometrial cancer, colorectal cancer, lung cancer and tumor agnostic biomarker driven cancers. We look forward to sharing updates on the ABILITY-1 trial and the NEO-CYT study during the second half of 2026."

NEO-CYT is a randomized, multicenter Phase 1b trial evaluating MDNA11 in combination with nivolumab, with or without ipilimumab, as neoadjuvant therapy in patients with high-risk, surgically resectable Stage IIIB/C/D cutaneous melanoma. The study is sponsored by Fondazione Melanoma Onlus and led by Professor Paolo A. Ascierto of the Istituto Nazionale Tumori Fondazione "G. Pascale" in Naples, Italy.

The trial represents an important expansion of MDNA11’s clinical development into an earlier-line, curative-intent melanoma setting. Neoadjuvant immunotherapy, administered before surgery while the tumor and its immune microenvironment remain intact, has emerged as a promising strategy to generate deeper anti-tumor immune responses and improve long-term outcomes for patients with high-risk resectable melanoma. However, a meaningful proportion of patients still do not achieve a major pathologic response with checkpoint-based neoadjuvant therapy, underscoring the need for novel immune-activating approaches that may improve depth and durability of response.

The NEO-CYT poster at ASCO (Free ASCO Whitepaper) highlighted the scientific rationale for combining MDNA11 with checkpoint inhibitors in the neoadjuvant setting. Prior clinical and translational research has shown that lack of response to neoadjuvant checkpoint therapy may be associated with an immunologically "cold" tumor microenvironment, including IL-2–related immune features. MDNA11 was designed to selectively engage the IL-2 receptor beta pathway, promoting expansion and activation of CD8+ T cells and NK cells that are central to anti-tumor immunity, while minimizing stimulation of immunosuppressive regulatory T cells.

The study is expected to enroll up to 80 patients across four treatment arms. The control arm will comprise of patients treated with the current gold-standard, ipilimumab plus nivolumab, while investigational arms will evaluate MDNA11 in combination with nivolumab alone, MDNA11 in combination with ipilimumab plus nivolumab, and an optional arm adding tocilizumab to MDNA11 plus ipilimumab and nivolumab following Steering Committee safety review.

The primary efficacy endpoint is Major Pathologic Response at surgery, defined as 10% or less viable tumor in the treated tumor bed. Co-primary safety endpoints include the incidence, severity and duration of treatment-related adverse events, with particular focus on immune-related adverse events.

MDNA11 is also being evaluated in Medicenna’s ongoing Phase 1/2 ABILITY-1 study, where it has demonstrated immune activation, including expansion of CD8+ T cells and NK cells, as well as single-agent clinical activity and a manageable safety profile in patients with advanced solid tumors. Together, NEO-CYT and ABILITY-1 are intended to inform Medicenna’s broader development strategy for MDNA11 across multiple treatment settings, including earlier-line melanoma populations where patients may have more intact immune systems and greater potential to benefit from immunotherapy.

Clinical updates from MDNA11 studies are anticipated in the second half of 2026.

About High-Risk Stage III Surgically Resectable Melanoma

Melanoma is the fifth most common cancer in the United States and the most lethal form of skin cancer. Stage III melanoma refers to disease that has spread beyond the primary tumor to regional lymph nodes or nearby tissue, but not to distant organs. In high-risk Stage III melanoma, patients face a significant risk of recurrence even after complete surgical removal, underscoring the need for effective systemic treatment strategies. Neoadjuvant immunotherapy, administered before surgery while the tumor and its immune microenvironment remain intact, has emerged as a promising approach to improve pathologic responses and long-term outcomes in this setting.

About MDNA11

MDNA11 is a long-acting, ‘beta-enhanced not-alpha’ IL-2 Superkine specifically engineered to overcome the shortcomings of aldesleukin and other next generation IL-2 variants by preferentially activating immune effector cells (CD8+ T and NK cells) responsible for killing cancer cells, with minimal or no stimulation of immunosuppressive Tregs. These unique proprietary features of the IL-2 Superkine have been achieved by incorporating seven specific mutations and genetically fusing it to a recombinant human albumin scaffold to improve the pharmacokinetic (PK) profile and pharmacological activity of MDNA11 due to albumin’s natural propensity to accumulate in highly vascularized sites, in particular tumor and tumor draining lymph nodes. MDNA11 is currently being evaluated in the Phase 1/2 ABILITY-1 study as both monotherapy and in combination with pembrolizumab.

About Fondazione Melanoma Onlus

Fondazione Melanoma Onlus is a non-profit organization based in Naples, Italy, that supports and promotes melanoma research, education, and clinical trials. It is known for organizing international conferences like the Melanoma Bridge, which bring together clinicians and researchers to discuss advancements in melanoma treatment and its related fields. The foundation also sponsors scientific awards for outstanding achievements in melanoma research.

(Press release, Medicenna Therapeutics, JUN 3, 2026, View Source [SID1234666410])

On June 3, 2026 Lantheus Holdings, Inc. ("Lantheus" or the "Company") (NASDAQ: LNTH), the leading radiopharmaceutical-focused company dedicated to helping clinicians Find, Fight, and Follow disease to deliver better patient outcomes, reported John Wiggins, Vice President, External Manufacturing, will participate in a fireside chat at the Goldman Sachs 47th Annual Global Healthcare Conference at 8:40 a.m. ET on Tuesday, June 9.

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To access the live webcast of the presentations, please visit the Investors section of the Company’s website at www.lantheus.com. A replay of the webcasts will be available on the Company’s website for at least 30 days following the live presentation.

(Press release, Lantheus, JUN 3, 2026, View Source [SID1234666409])

On June 3, 2026 Kura Oncology, Inc. (Nasdaq: KURA), a biopharmaceutical company focused on precision medicines for the treatment of cancer, reported new clinical and translational data supporting darlifarnib as a potential foundational combination platform for KRAS-mutant cancers and other targeted therapy settings. The data, presented at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting, support Kura’s strategy to expand its next-generation farnesyl transferase inhibitor (FTI) through a new platform study designed to efficiently evaluate multiple combinations and identify opportunities to improve the depth and durability of responses to targeted therapies.

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"Today’s data release and strategic update reinforce our belief that darlifarnib represents much more than a single combination opportunity," said Troy E. Wilson, Ph.D., J.D., President and Chief Executive Officer of Kura Oncology. "With FTI clinical proof-of-concept now demonstrated in three distinct targeted therapy settings, and translational data supporting applicability across the evolving RAS inhibitor landscape, we believe darlifarnib has the potential to become a foundational combination backbone for molecularly defined cancers. Our planned platform study is designed to accelerate development across multiple combinations and disease settings, beginning with darlifarnib plus daraxonrasib in KRAS-mutant pancreatic cancer."

In preclinical models, translational data demonstrated that darlifarnib inhibits RHEB farnesylation and sustains suppression of mTORC1 signaling, a pathway implicated in adaptive resistance to KRAS inhibition. Preclinical studies further showed enhanced anti-tumor activity across multiple classes of RAS inhibitors, including mutant-selective and multi-selective RAS(ON) inhibitors, as well as pan-KRAS and pan-RAS approaches, and demonstrated tumor regressions in models previously exposed to KRAS inhibitor therapy.

FIT-001 ASCO (Free ASCO Whitepaper) Update

In the ongoing FIT-001 study, darlifarnib plus adagrasib demonstrated promising anti-tumor activity in heavily pretreated patients with KRAS G12C-mutated pancreatic ductal adenocarcinoma (PDAC), non-small cell lung (NSCLC), and colorectal (CRC) cancers. Among 26 response-evaluable patients, tumor shrinkage was observed in 77% of patients overall and in 94% of KRAS inhibitor-naïve patients. Confirmed objective response rates included 67% in PDAC, 50% in NSCLC, and 29% in KRAS inhibitor-naïve CRC. Clinical activity was also observed in patients previously treated with KRAS inhibitors.

Observed response rates compared favorably with historical adagrasib monotherapy benchmarks, supporting the hypothesis that darlifarnib may enhance the depth and durability of response when combined with KRAS-targeted therapies.

The ASCO (Free ASCO Whitepaper) findings represent the third clinical validation of Kura’s FTI combination strategy, following previously reported activity in renal cell carcinoma and PIK3CA-mutated head and neck cancer.

Planned Platform Study

Kura believes the opportunity for darlifarnib extends beyond KRAS G12C. The Company plans to initiate a platform study designed to evaluate darlifarnib across multiple targeted therapy combinations and disease settings. The flexible design is intended to allow combinations with both approved and investigational targeted therapies, add new arms over time, and advance successful combinations into dedicated registrational studies.

Given the emerging clinical and translational data, Kura has seen growing interest in exploring darlifarnib across a variety of targeted therapy settings. The Company’s planned platform study is designed to provide a flexible framework that could support evaluation of additional combination opportunities over time. The first planned combination in the new study will be darlifarnib plus daraxonrasib in 2L+ KRAS-mutant PDAC, which is expected to enter Phase 1a evaluation in early 2027.

"The KRAS treatment landscape is evolving rapidly, with multiple next-generation mutant-selective and pan-RAS approaches advancing through clinical development," said Mollie Leoni, M.D., Chief Medical Officer of Kura Oncology. "Our data suggest darlifarnib may have broad applicability across this expanding class of therapies, creating the opportunity to improve outcomes for patients while establishing a flexible platform for future development and collaboration."

Virtual Investor Event
Kura will host a webcast and conference call on June 3, 2026, at 12:15 p.m. PT / 3:15 p.m. ET featuring management and David S. Hong, M.D., Deputy Chair of the Department of Investigational Cancer Therapeutics, The University of Texas M.D. Anderson Cancer Center. The live webcast and replay will be available on the Company’s website at www.kuraoncology.com under the Investors tab in the Events and Presentations section.

(Press release, Kura Oncology, JUN 3, 2026, View Source [SID1234666408])

On June 3, 2026 Karyopharm Therapeutics Inc. (Nasdaq: KPTI), a commercial-stage pharmaceutical company pioneering novel cancer therapies, reported that it will participate in a virtual fireside chat hosted by Cantor on June 8, 2026 at 12:00 p.m. ET. The event will feature the Company’s senior management team and Robert Coleman, MD, FACOG, FACS, a globally recognized gynecologist oncologist and Principal Investigator of the Phase 3 XPORT-EC-042 trial.

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Institutional investors interested in attending the live event should contact their Cantor representative. A replay of this event will be available on June 8, 2026 at approximately 2:00pm ET under "Events and Presentations" in the Investors & Media section of the Company’s website.

(Press release, Karyopharm, JUN 3, 2026, View Source,-2026 [SID1234666407])