The final immunotherapy that Sartor discussed was BPX-101, a dendritic cell (DC) vaccine intended for patients with mCRPC. This vaccine is comprised of mature, antigenâ€expressing DCs derived from monocytes collected during outpatient leukapheresis. It is then developed by manipulating the survival and activation state of the autologous DC in situ (Figure 4
). During this process, the cells are modified so that a proprietary drug (AP1903) can activate the vaccine for a timed response. According to Bellicum Pharmaceuticals, the company developing the vaccine, “BPX-101 is administered intradermally, followed 24 hours later by a 2-hour infusion of AP1903. This 1-day delay gives the cells time to migrate to the patient’s lymph nodes, where they are activated by AP1903—in the right place and at the right time to drive a maximal anticancer immune response.”
Sartor says the vaccine has shown significant tumor responses. A phase 1/2 clinical trial of BPX-101 included scans of a patient with mCRPC after docetaxel chemotherapy, metastatic to lungs, lymph nodes, and bone, with a Halabiâ€predicted survival of 12.5 months. The patient was treated with 6 doses of BPXâ€101 starting 6 weeks after baseline scans. Six measurable metastatic lesions in the lungs were eliminated by the end of the 12-week induction phase of treatment (20 weeks after baseline scans). Metastases at other sites were stable at 12 weeks. He remains alive with progressive disease 10 months after enrollment.
Potential synergy between BPXâ€101 and docetaxel chemotherapy, with single or more limited dosing, will be further explored in a phase 1 extension study. A phase 2 clinical trial using BPXâ€101 and AP1903 is now enrolling patients.
When considering cost, convenience, safety, and specificity, no ideal immunotherapy or strategy has been approved for patients with prostate cancer. But recent advancements have shown that each new therapy offers promise that further treatments may someday make prostate cancer a chronic condition rather than a deadly disease.
All Slides Courtesy of A. Oliver Sartor, MD