For patients with advanced hormone-refractory prostate cancer, the agent Xofigo® (radium-223) appears similarly effective in patients who have and have not received Taxotere® (docetaxel), a chemotherapy drug that can be used in the treatment of advanced prostate cancer. These findings were recently published in The Lancet Oncology.

Prostate cancer is a hormonally sensitive disease that can often be controlled for long periods with androgen-deprivation therapy (ADT). When prostate cancer stops responding to this treatment, it is referred to as hormone-refractory prostate cancer. Metastatic hormone-refractory prostate cancer is a challenging form of the disease to treat because the cancer has spread to distant sites in the body and does not respond to treatment with standard hormonal therapy.

Xofigo is a radiopharmaceutical agent that binds with minerals in the bone to deliver radiation directly to bone tumors, thereby limiting the damage to the surrounding normal tissues. The U.S. Food and Drug Administration (FDA) approved the drug in May 2013 after a trial known as Alpharadin in Symptomatic Prostate Cancer Patients (ALSYMPCA) was stopped early after an interim analysis showed that treatment with Xofigo significantly improved survival, compared with placebo. Continued analysis form the ALSYMPCA trial now indicates that Xofigo is similarly active in both patients who have and have not received treatment with Taxotere.

To evaluate the effect of Xofigo in patients who had and had not received Taxotere, researchers divided participants in the ALYSYMPCA trial in two treatment groups:

  • One group received six injections with Xofigo (one injection given every four weeks).
  • The other group received the same injection schedule with a placebo (inactive substitute).

All participants had advanced hormone-refractory prostate cancer and at least two bone metastases. The researchers noted whether or not the patients had received Taxotere. Of the 921 patients in the trial, 526 had received Taxotere; 352 of these patients received Xofigo during the trial, and 174 received placebo. The remaining patients had not previously received Taxotere (262 in the Xofigo group and 133 in the placebo group).

Xofigo appeared active in patients with advanced hormone-refractory prostate cancer, whether or not they had received previous treatment with Taxotere. Both patients who had and had not been treated with Taxotere had longer median survival than patients who received placebo. As well, patients who had previously been treated with Taxotere had a significantly longer median time before their first symptomatic skeletal event (pathological fracture, radiation therapy to bone, surgery to bone, or spinal cord compression) compared with those who had not received Taxotere: about 15 months versus about eight months.

Side effects for Xofigo were similar between patients who had and hadn’t received Taxotere. They occurred in 62% of those who had received Taxotere and in 54% of those who had not. Side effects included thrombocytopenia (low platelet counts), anemia, and neutropenia (low neutrophil counts, a type of blood cell that fights infection).

Based on these trial results, the researchers concluded that Xofigo appears effective in patients with advanced hormone-refractory prostate cancer, whether or not they’ve had previous treatment with Taxotere. Xofigo also appears well tolerated in these patients.

Reference: Hoskin P, Sartor O, O’Sullivan JM, et al. Efficacy and Safety of Radium-223 Dichloride in Patients with Castration-Resistant Prostate Cancer and Symptomatic Bone Metastases, with or without Previous Docetaxel Use: a Prespecified Subgroup Analysis from the Randomised, Double-Blind, Phase 3 ALSYMPCA Trial. The Lancet Oncology. doi:10.1016/S1470-2045(14)70474-7.

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