Aktis Oncology (NASDAQ:AKTS) said new imaging and dosimetry data for its investigational radiopharmaceutical AKY-2519 support the company’s plan to advance the drug candidate across prostate cancer and other B7-H3-expressing solid tumors.
The company discussed the findings on a conference call tied to two posters scheduled for presentation at the ASCO annual meeting on May 30. President and CEO Matt Roden said AKY-2519 is Aktis’ second clinical-stage program and is designed to target B7-H3 while delivering actinium-225, an alpha-emitting isotope.
ASCO Posters Cover Prostate Cancer and Broader Solid Tumors
Chief Medical Officer Akos Czibere said the ASCO presentations include data from 34 patients across academic centers in South Africa and Germany. One poster covers imaging, biodistribution and dosimetry in 16 patients with metastatic castration-resistant prostate cancer. A second poster reports PET/CT imaging analyses in patients with various B7-H3-expressing solid tumors.
Czibere said AKY-2519 was generally well tolerated in the imaging and dosimetry study, with no adverse events or infusion-related reactions reported. He said the data showed “robust tumor uptake and retention” out to at least six days on serial imaging, along with decreasing and limited normal tissue exposure.
The prostate cancer assessment used gallium-68 and lutetium-177 imaging isotopes. Czibere said the SPECT/CT data were converted to predicted absorbed doses for actinium-225, the therapeutic isotope Aktis intends to use. Across 12 patients with available data, the company reported average predicted absorbed doses over a four-course treatment schedule using an exemplary 8 megabecquerel dose of actinium-225 of 1.3 gray to bone marrow, 9.9 gray to liver, 16 gray to kidneys and 4.2 gray to salivary glands.
For tumors, Czibere said the company observed predicted absorbed doses of 141 to 268 gray for nodal metastases and 48 to 121 gray for bone disease under the same four-dose assumption. He said the findings suggest a favorable therapeutic index and support repeat dosing at clinically meaningful levels.
Potential Differentiation From PSMA-Targeted Therapies
Czibere said matched imaging using PSMA-11 and AKY-2519 showed AKY-2519 consistently identified lesions also identified by PSMA imaging agents, suggesting co-expression of B7-H3 and PSMA in prostate cancer. He said additional analyses of the full cohort will be presented at a future conference.
Oliver Sartor, a clinical investigator and strategic adviser to Aktis, said the data were “very preliminary” but “very promising.” Sartor said he was focused on three features: tumor retention, kidney exposure and bone marrow clearance. He described the results as a “trifecta,” citing “really nice retention in the tumor, really minimal exposure to the kidney, and rapid enough clearance to not expose the bone marrow.”
Sartor also said alpha emitters could offer advantages over beta-emitting therapies such as PLUVICTO, based on the absorbed doses discussed on the call. He noted that salivary gland toxicity has been an issue with some PSMA-targeted alpha therapies, while bone marrow toxicity has been a concern with antibody-based approaches.
Development Plans Include Prostate and Lung-Focused Trials
Aktis said it has initiated a Phase I-B prostate cancer study of AKY-2519 in metastatic castration-resistant prostate cancer. The trial is enrolling separate cohorts of PLUVICTO-naive and PLUVICTO-experienced patients, with independent dose escalations across 6, 9 and 12 megabecquerel levels. The company expects to report preliminary data from the trial in 2027.
The company also outlined a planned lung cancer-focused basket trial in B7-H3-expressing tumor types. Czibere said the protocol is active under the company’s IND and remains on track to begin dosing patients in the second half of the year. The trial design includes dose escalation and dedicated expansions for non-small cell lung cancer and other B7-H3-expressing solid tumors.
Tim Yap, vice president and head of clinical development at the Therapeutics Discovery Division at MD Anderson Cancer Center, said B7-H3 is viewed as an “exceptionally promising target” and a “near universal target for solid tumors.” He cited potential opportunities in small cell lung cancer, non-small cell lung cancer, metastatic colorectal cancer, head and neck squamous cell carcinoma, osteosarcoma, neuroblastoma and glioblastoma.
Roden said Aktis’ broader pipeline also includes AKY-1189, which has FDA Fast Track designation and is enrolling in a Phase I-B clinical trial in the U.S. The company expects to present preliminary dose escalation data for that program in the first quarter of 2027.
About Aktis Oncology (NASDAQ:AKTS)
Aktis Oncology (NASDAQ: AKTS) is a biotechnology company focused on the discovery and development of new therapies for cancer. The firm concentrates on advancing oncology candidates through research and development with the goal of addressing unmet medical needs in oncology. Its work emphasizes targeted and precision approaches intended to improve the safety and efficacy profiles of cancer treatments.
The company’s activities include laboratory research, preclinical studies and clinical development as it advances its pipeline programs toward regulatory milestones.
