Prostate cancer retreatment with sipuleucel-T may be possible, according to Tomasz Beer, MD, a leading prostate cancer researcher and Deputy Director at the Oregon Health and Science University, Knight Cancer Institute in Portland. Dr. Beer presented results from his study at the 2013 American Society of Clinical Oncology meeting.
What is sipuleucel-T?
Sipuleucel-T is a form of immunotherapy that boosts your own immune system to fight against your prostate cancer. In a procedure very similar to donating blood, your immune cells are harvested and then they undergo a special treatment. You receive your treated immune cells (i.e. the sipuleucel-T treatment) back in a blood transfusion-like procedure. The cells treated with sipuleucel-T stimulate your body’s immune system response against the prostate cancer cells in your body.
What happened in the study?
The study examined seven patients who all had previously participated in a phase III sipuleucel-T clinical trial. In the prior study these patients had received sipuleucel-T, currently marketed under the brand name Provenge, when they developed a rising PSA level following prostatectomy. To be eligible for retreatment with sipuleucel-T, patients needed to meet the current treatment indications for sipuleucel-T, which include:
- A rising PSA level despite standard hormone therapy.
- Metastatic disease, or the prostate cancer has spread to other parts of the body.
- Narcotics are not needed for pain or symptom control.
All the men had a good performance status, and the median or middle age was 70. The participants received the current standard treatment, which is three infusions of sipuleucel-T over six weeks. The study examined several different measures of immune status as well as safety parameters.
The median time between the most recent and previous sipuleucel-T infusion was just over nine years. Immune responses appeared to be greater with the most recent clinical trial treatment compared to the response in the previous clinical trial indicating, at least preliminarily, that there was some boosting of immune response based on prior treatment. Additionally, before the most recent treatment there was still evidence of an immune response indicating some long-term immune memory.
While very small, this study indicates that retreatment with sipuleucel-T is feasible. Additionally, it appears that there is some amount of immunological memory of the prior treatment and that retreatment boosts prior immune levels. While this current study will not change therapy indications or recommendations for sipuleucel-T, further analysis of this current study will be performed in addition to more planned studies with larger numbers of patients.
Read more in our Prostate Cancer Health Center.
ASCO 2013 – Podcast: Open-label, multicenter study of sipuleucel-T in men with metastatic castrate resistant prostate cancer (mCRPC) previously treated with sipuleucel-T: Evaluation of antigen presenting cell (APC) activation and ELISPOT data.