Through-the-skin drug delivery eases prostate cancer treatment
When prostate cancer patients need therapy to reduce male hormone levels, delivering some of the treatment via a patch on the skin may be just as effective as traditional means of administration with fewer side effects, according to a mid-stage study.
Prostate cancer cells usually require male androgen hormones, such as testosterone, to grow. Androgen deprivation therapy (ADT) employs drugs that block the androgens’ “pathway” to receptor proteins on cancer cells, along with so-called luteinizing hormone-releasing hormone (LHRH) drugs that are injected or implanted to lower the testicles’ production of testosterone.
Side effects of the treatments include hot flashes, fatigue, memory problems, and bone density loss.
In the new trial, being presented at the 2025 ASCO Genitourinary Cancers Symposium in San Francisco, 79 patients with prostate cancer all received androgen receptor pathway inhibitor drugs. In addition, they were randomly assigned to receive either LHRH drugs or a transdermal patch containing estradiol, a form of the female hormone estrogen.
Transdermal estradiol, currently used for menopausal hormone therapy, is a potentially attractive alternative to ADT, study leader Dr. Nick James of the Institute of Cancer Research, The Royal Marsden NHS Foundation Trust, in London said in a statement.
He explained that it suppresses testosterone without estrogen depletion; increases bone density; it’s inexpensive; and avoids the blood clot risk associated with oral estrogen.
Within six months, 61% of patients in each arm were responding well to treatment, as assessed by their blood levels of prostate-specific antigen.
Patients using the estradiol patches had a lower rate of hot flashes than those on LHRH drugs - 5% versus 24% - and a lower rate of high blood pressure - 5% compared with 17%.
Enlargement of breast tissue was more common in the estradiol patch group, however.
It will be some time before the researchers can assess whether the patches were non-inferior to the LHRH drugs in terms of metastasis-free survival, or length of time without the disease spreading.
They noted that in two earlier trials, estradiol patches were equivalent to LHRH in rates of androgen suppression, superior at improving metabolic parameters, quality of life, and bone density, and non-inferior in achievement of metastasis-free survival among men with locally advanced disease.
Estradiol patches could be particularly attractive to patients who are on an LHRH drug and are troubled by side effects like hot flashes, James said.
They also have appeal from a cost standpoint, he added.
“This sort of repurposing of an older, cheap drug is an important way to improve outcomes, separate from developing new drugs,” he said.