On April 21, 2023 Oncoinvent AS, a clinical stage company advancing alpha emitter therapy across a variety of solid cancers, reported the online publication of two articles in the recent special edition of Frontiers in Medicine focused on alpha radioisotopes (Press release, Oncoinvent, APR 21, 2023, View Source [SID1234630391]). The first article, titled "Radiation safety considerations for the use of radium-224-calciumcarbonate-microparticles in patients with peritoneal metastasis," focuses on the effective radiation dose limit for hospital workers, carers, and the public from patients receiving 224Ra-CaCO3-MP. The second, titled "First experience with 224Radium-labeled microparticles (Radspherin) after CRS-HIPEC for peritoneal metastasis in colorectal cancer (a phase 1 study)," supports the favorable safety profile of Radspherin and establishes sustained tolerability in all dose levels for patients treated to date with colorectal cancer.
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"We are excited to share these compelling and important publications in this special edition of Frontiers in Medicine, which continue to demonstrate that all dose levels of Radspherin are well tolerated with no dose limiting toxicities to date," said Jan A. Alfheim, Chief Executive Officer of Oncoinvent. "Additionally, with these publications, we have shown that no precautions related to external exposure should be required for patients treated with 224Ra-CaCO3-MP – a major risk factor to consider in radiopharmaceutical development that has now been significantly reduced. We are highly encouraged by the clinical data we have obtained to date and look forward to leveraging our expertise as a leader within the radiopharmaceutical space and progressing the clinical development of Radspherin."
In the publication titled "Radiation safety considerations for the use of radium-224-calciumcarbonate-microparticles in patients with peritoneal metastasis," six patients with colorectal cancer from the phase 1 trial were injected with 7 MBq of 224Ra-CaCO3-MP. At 3, 24, and 120 hours post injection, the patients underwent measurements with an ionization chamber and a scintillator-based iodide detector as well as whole body gamma camera imaging. Researchers also collected urine and blood samples post injection to estimate activity concentration of 224Ra and 212Pb. It was found that the patients’ median effective whole-body half life of 224Ra-CaCO3-MP ranged from 2.6 to 3.7 days, with a mean value of 3.0 days. Importantly, in the scenarios with exposure at the hospital, sporadic patient contact resulted in a range of 3.9–6.8 μSv per patient, and daily contact resulted in 4.3–31.3 μSv depending on the scenario, suggesting that a single hospital worker can treat around 200-400 patients injected with 224Ra-CaCO3-MP before external exposure is exceeded. Family members and other members of the public were expected to receive well below 0.25 mSv, thereby eliminating the need for restrictions to reduce external exposure. These data demonstrate that, due to low dose rates from the patients and low amount of activity found in blood and urine, no precautions related to external exposure are required when treating patients with Radspherin.
In the publication titled "First experience with 224Radium-labeled microparticles (Radspherin) after CRS-HIPEC for peritoneal metastasis in colorectal cancer (a phase 1 study)," 23 patients were enrolled and administered Radspherin at increasing activity dose levels of 1-2-4-7 over a period of 30 days. A total of 68 grade 2 adverse events were reported for 17 patients during the first 30 days; most were considered related to CRS and/or HIPEC. No DLT was documented at the 7 MBq dose level that was then defined as the recommended dose. Additionally, the biodistribution of Radspherin showed a relatively even peritoneal distribution. These results underscore that all dose levels of Radspherin were well tolerated, and DLT was not reached. Of note, no deaths occurred, and no serious adverse events were considered related to Radspherin. This favorable safety profile in the current study is in line with documentation from other preclinical and clinical studies with other related alpha-emitting compounds administered intraperitoneally.