For patients with early-stage prostate cancer being managed by active surveillance, adding the hormonal agent apalutamide may lower the rate of positive biopsies during follow-up, suggest findings from a preliminary clinical trial published by Schweizer et al in The Journal of Urology.

"In our study, 59% of [patients] receiving 90 days of treatment with apalutamide had no evidence of residual prostate cancer on follow-up biopsy immediately posttreatment," commented lead author Michael T. Schweizer, MD, of the University of Washington and Fred Hutchinson Cancer Center. "Our preliminary findings support further studies to determine whether adding hormonal therapy might aid in reducing or preventing progression of early-stage prostate cancers during active surveillance."

Active surveillance is a treatment option for some patients with early-stage, slow-growing, low-risk or localized prostate cancer, potentially avoiding or delaying the need for definitive treatment such as surgery or radiation. Patients opting for active surveillance typically undergo regular prostate-specific antigen (PSA) screenings, prostate exams, imaging tests, and repeat biopsies in order to carefully monitor prostate cancer growth or progression. Although active surveillance is increasingly regarded as a standard of care for patients with low-risk prostate cancer, many patients eventually need further treatment.

Apalutamide is one of a class of potent novel hormonal agents approved for the treatment of advanced prostate cancer. “Because of its antitumor effectiveness, apalutamide may also have the potential to control or shrink early forms of prostate cancer,” Dr. Schweizer added. “In addition, by avoiding reductions in testosterone levels, apalutamide may reduce sexual dysfunction and the many other side effects that can linger after stopping conventional hormone therapies.”

Current Study

The preliminary (phase II) clinical trial investigated whether adding apalutamide to active surveillance for patients with early-stage prostate cancer might affect the rate of cancer detection in follow-up biopsies. The study included 23 patients with an average age of 67 years who opted for active surveillance for initial treatment of low- to intermediate-risk prostate cancer. All patients received 90 days of oral apalutamide at 240 mg per day.

Fifty-nine percent of patients (13/22) who completed apalutamide treatment as planned had no evidence of residual cancer on immediate posttreatment biopsy. Upon long-term follow-up, rates of cancer-free biopsies were 33% at 1 year (7/21) and 21% at 2 years (4/19).

In 65% of patients included in the study, PSA levels decreased by 90% or more with the addition of apalutamide. Five patients eventually underwent radiation or surgery for prostate cancer at a median of about 2 years.

In contrast to the effects of conventional hormonal therapies (ie, LHRH agonists/antagonists), testosterone levels increased during apalutamide treatment, with a "minimal and transient" impact on quality of life. That's an important finding, because minimizing treatment impact on everyday functioning is a key reason why patients opt for active surveillance.

Dr. Schweizer and coauthors noted that their small, preliminary trial did not include a comparison group of patients not receiving apalutamide. However, the immediate negative biopsy rate of 59% was higher than reported in previous studies of active surveillance. "Ultimately," the researchers wrote, "large, randomized studies designed to detect differences in clinically relevant endpoints will be needed to evaluate if systemic therapies are useful in the management of patients with prostate cancer followed on active surveillance."

Disclosure: For full disclosures of the study authors, visit auajournals.org.