The US Food and Drug Administration (FDA) has today approved sipuleucel-T (Provenge), a new therapy for certain men with advanced prostate cancer that uses their own immune system to fight the disease.
Provenge is indicated for the treatment of asymptomatic or minimally symptomatic prostate cancer that has spread to other parts of the body and is resistant to standard hormone treatment.
“The availability of [sipuleucel-T] provides a new treatment option for men with advanced prostate cancer, who currently have limited effective therapies available,” said Karen Midthun, MD, FDA’s Center for Biologics Evaluation and Research, Rockville, Maryland.
The effectiveness of sipuleucel-T was studied in 512 patients with metastatic hormone treatment refractory prostate cancer in a randomised, double-blind, placebo-controlled, multicentre trial, which showed an increase in overall survival of 4.1 months.
The median survival for patients receiving sipuleucel-T treatments was 25.8 months, compared with 21.7 months for those who did not receive the treatment.
Almost all of the patients who received sipuleucel-T had some type of adverse reaction. Common adverse reactions reported included chills, fatigue, fever, back pain, nausea, joint ache, and headache.
What is advanced prostate cancer?
Prostate cancer is defined as ‘‘advanced’’ when it spreads outside the prostate gland. It may spread to nearby tissues, lymph nodes, bones, or other parts of the body. When it is spread beyond the tissues directly adjacent to the prostate gland, it is called metastatic prostate cancer.
The majority of adverse reactions were mild or moderate in severity. Serious adverse reactions, reported in approximately one quarter of the patients receiving sipuleucel-T, included some acute infusion reactions and stroke. Cerebrovascular events, including haemorrhagic and ischaemic strokes, were observed in 3.5% of patients in the sipuleucel-T group, compared with 2.6% of patients in the control group.
Advanced Prostate Cancer Early detection
Doctors agree that the prostate-specific antigen (PSA) blood test is not a perfect test for finding prostate cancer early. It misses some cancers, and in other cases it is elevated when cancer isn’t present. Researchers are working on two strategies to address this problem.
One approach is to try to improve on the test that measures the total PSA level, as described in the section “Can prostate cancer be found early?” The percent-free PSA is one way to do this, although it requires two separate tests. Another option might be to measure only the “complexed” PSA (the portion of PSA that is not “free”) to begin with, instead of the total and free PSA. This one test could give the same amount of information as the other two done separately. Studies are now under way to see if this test provides the same level of accuracy.
The other approach is to develop new tests based on other tumor markers. Several newer blood tests seem to be more accurate than the PSA test, based on early studies. Early results have been promising, but these and other new tests are not yet available outside of research labs and will need more study before they are widely used to test for prostate cancer.
Other new tests being studied are urine tests. One test, called Progensa®, looks at the level of prostate cancer antigen 3 (PCA3) in the urine. The higher the level, the more likely that prostate cancer is present. In studies, it was used along with the PSA test.
Another test looks for an abnormal gene change called TMPRSS2:ERG in prostate cells. The cells to be tested are found in urine collected after a rectal exam. This gene change is found in about half of all localized prostate cancers. It is rarely found in the cells of men without prostate cancer. Studies are under way to develop this into a test for early detection of prostate cancer.
Sipuleucel-T is an autologous cellular immunotherapy, designed to stimulate a patient’s own immune system to respond against the cancer. Each dose of sipuleucel-T is manufactured by obtaining a patient’s immune cells from the blood. To enhance their response against the cancer, the immune cells are then exposed to a protein that is found in most prostate cancers, linked to an immune stimulating substance. After this process, the patient’s own cells are returned to the patient to treat the prostate cancer. Sipuleucel-T is administered intravenously in a 3-dose schedule given at about 2-week intervals.
SOURCE: US Food and Drug Administration