Immunotherapy shown to extend life expectancy in metastatic prostate cancer

A new analysis of the phase 3 IMPACT study has found that sipuleucil-T (Provenge, Dendreon) increases survival times by an estimated median of 7.8 months in patients with asymptomatic or minimally symptomatic metastatic castrate-resistant prostate cancer.

In addition, 3 exploratory or phase 2 studies found that sipuleucil-T appears to activate the immune response against prostate cancer in patients with localized cancer as well. A percentage of patients treated early with sipuleucil-T appear to survive even longer.

The important things for pharmacists to know about sipuleucil-T are that it is an autologous therapy that should be used for asymptomatic or minimally symptomatic disease and that it will take time to see results, according to Dr George. "We don't expect an immediate treatment response with [the treatment]," he noted.

Results from 4 studies of sipuleucil-T were presented at the American Society of Clinical Oncology 2012 Genitourinary Cancers Symposium (ASCO-GU) in San Francisco. The finding on survival time is an improvement over the first studies of sipuleucil-T that found an estimated median overall survival benefit of 4.1 months.

The treatment was approved by FDA as the first autologous cellular immunotherapy against cancer. Patients undergo leukapheresis to remove white blood cells, which are then sent to Dendreon, where they are incubated with antigen prostatic acid phosphatase and granulocyte-macrophage colony stimulating factor. The product is then sent back and infused into the patient in 3 courses of treatment with 2 weeks between treatments.

The most common side effects of sipuleucel-T are chills, fever, fatigue, nausea, and headache, which generally occur during the first days of treatment. However, cerebrovascular events were seen in 2.4% of patients treated with sipuleucel-T compared to only 1.8% of placebo-treated patients.