Dr. Antonarakis on Trial Examining Sipuleucel-T Plus Radium-223 in Bone-Metastatic CRPC

Emmanuel S. Antonarakis, MBBCh, professor of oncology, Johns Hopkins Medicine, discusses the design of a randomized phase II study of sipuleucel-T (Sip-T) with or without radium-223 dichloride (Xofigo) in men with asymptomatic bone-metastatic castrate-resistant prostate cancer (mCRPC).

The investigator-initiated, open-label, randomized, multicenter phase II trial looked at 30 patients with mCRPC, making it a small patient population, says Antonarakis. Fifteen patients with mCRPC who were asymptomatic or minimally symptomatic were randomized to receive standard sipuleucel-T alone or sipuleucel-T plus radium-223.

In the combination group, it was a bit logistically challenging, says Antonarakis, because patients started off with radium-223, given once every 4 weeks, per the FDA-approved dose and schedule for that agent. After 2 doses of radium-223, they then received sipuleucel-T, which was given in 3 doses every 2 weeks, adds Antonarakis. Then the patients received the third, fourth, fifth, and sixth dose of radium-223. As such, the sipuleucel-T was sandwiched in between the radium-223 injections, concludes Antonarakis.