Bayer's Radium-223 Dichloride Injection Nears Approval in China for Prostate Cancer Bone Metastasis

By Baihuawen

On August 15, Bayer’s marketing application for Radium-223 (²²³Ra) injection in China entered the “under review” stage, with approval expected soon for the treatment of bone metastases from prostate cancer.

Radium-223 dichloride (²²³Ra) injection is an alpha-particle-emitting radiopharmaceutical therapeutic agent. Its active moiety mimics calcium ions and selectively targets bone tissue by forming complexes with hydroxyapatite, thereby prolonging patient survival while reducing pain and discomfort associated with bone metastases, ultimately improving patients' quality of life. The drug was first approved by the U.S. Food and Drug Administration (FDA) on May 15, 2013, under the brand name Xofigo, for the treatment of bone metastases in patients with castration-resistant prostate cancer.

Bayer had previously submitted a marketing application for Radium-223 Dichloride Injection on November 23, 2018, which unfortunately was not approved. On August 23, 2019, Bayer’s resubmitted marketing application for Radium-223 Dichloride Injection was accepted by the Center for Drug Evaluation (CDE). In September 2019, the CDE included the drug in its priority review program under Category (I)3, designated for drugs with significant therapeutic advantages.

Analysis of the Phase III ALSYMPCA study demonstrated that among 921 patients receiving standard therapy combined with either radium-223 dichloride or placebo, radium-223 dichloride significantly prolonged overall survival (14.9 vs. 11.3 months) and reduced the risk of death by 30% (HR 0.70).

Prostate cancer patients have a relatively longer survival period compared to those with other malignant tumors, but they are also prone to distant metastasis during long-term survival. The overall incidence of bone metastasis in castration-resistant prostate cancer is approximately 65%-75%, while in metastatic castration-resistant prostate cancer (mCRPC), the incidence of bone metastasis exceeds 90%. Patients with bone metastases often experience skeletal-related events, which increase the risk of death in prostate cancer patients by 28%.

Current medications for treating bone metastases in prostate cancer mainly include classic bisphosphonates, RANK inhibitors, and radiopharmaceuticals. Previously, radionuclide-based radiopharmaceuticals had significant adverse effects, and radiotherapy was not routinely recommended for prostate cancer patients. With a deeper understanding of radionuclides, radiopharmaceuticals have once again come into focus.