Effect of multipeptide vaccination therapy on disease outcome of patients with prostate cancer and biochemical recurrence

Abstract

PC is the most common cancer entity in men in Germany. The broad use of PSA screening has led to a significant increase of tumors diagnosed in a localized stage. Many of these patients undergo surgical therapy or radiation, although there is no clear evidence that this has a significant impact on the course of disease. Both surgery and radiotherapy are performed with a curative intention. However, a significant proportion of patients experiences biochemical disease recurrence. The optimal treatment of these patients with biochemical recurrence but no evidence of clinical recurrence is discussed controversially. A peptide vaccination against tumor specific surface antigens has shown efficacy in several tumor entities. Whether this approach might provide benefit for patients with biochemical relapse after prostatectomy is unclear. The aim of the present study was to evaluate the clinical outcome of patients taking part in a clinical trial evaluating the efficacy of a multipeptide vaccination for the treatment of patients with biochemical relapse. We analyzed data of 101 patients with PC who underwent RP and had a biochemical disease recurrence. 36 patients were treated with a multipeptide vaccination therapy and 65 served as a control group. We observed that in patients treated with vaccination therapy, the time to clinical recurrence tended to be longer compared to non-vaccinated patients. Moreover, we observed that the first non-vaccination therapy could be delayed in the group of patients receiving vaccination therapy. We observed no impact of vaccination therapy on cancer-specific and overall survival. The time to initiation of hormone deprivation therapy was not delayed significantly by peptide vaccination. The present study is the first evaluating a multipeptide vaccination for the treatment of biochemical relapse in patients with prostate cancer. In contrast to prior studies in other malignancies, the vaccination resulted in a significant delay of clinical recurrence whereas overall survival, an endpoint which is most frequently affected by immunization based therapies in cancer, was not changed. These results implicate that immune therapy might have a short to mid-term effect on tumor dynamics in patients with biochemical relapse but does not significantly affects the long-term course of the disease. Although the mechanisms potentially leading to the delay of clinical recurrence are unclear, the results of the present study encourage further investigations on the use of immunotherapy in patients experiencing biochemical relapse after treatment with a curative intention.