There has been widespread adoption of active surveillance (AS) for low risk prostate cancer. One important reason patients choose AS is to avoid the potential side effects of treatment whether it be surgery or radiation. Large studies have indicated that grade or stage progression occurs in roughly 40–50% of patients at 10 years, highlighting the more indolent and slow growing nature of this cancer.
Interest has arisen regarding strategies to delay the progression of low-risk prostate cancer. Most trials to date have involved nutraceuticals, such as pomegranate or green tea, which have often delivered conflicting data due in part to small trials and short periods of exposure (1). Efforts have also included 5-alpha reductase inhibitors such as dutasteride, a common medication used for urinary obstruction (REDEEM trial), and these have extended to more extensive androgen ablation techniques such as leuprolide with bicalutamide (2,3). Negative rebiopsy rates in these studies ranged from 36–45%. Notably, negative biopsy percentages in control groups can run from 20–40%.
A recent study presented by Michael Schweizer, MD, of the University of Washington presented at the Society of Urologic Oncology 2020 virtual annual meeting presented a small Phase 2 trial involving 23 men on AS for very low- to intermediate-risk PCa who received Apalutamide (4). Apalutamide is a potent androgen receptor-signaling inhibitor approved by the FDA for metastatic hormone-sensitive PCa and nonmetastatic castration-resistant PCa. The current trial included 15 patients (65%) with Grade Group 1 cancer and eight (35%) with Grade Group 2 cancer. Of these, 22 completed three months of Apalutamide therapy (240 mg daily) and were evaluable. Not surprisingly, all patients had a greater than 50% decline in PSA level. Post-treatment biopsies revealed no evidence of residual cancer in 13 (59%). Among 19 patients who had a second biopsy one year after enrollment, seven (37%) had no evidence of residual cancer. Side effects are important in this population and 79% of patients reported Grade 1 or 2 fatigue (79%), gynecomastia (70%), and rash (26%). Cognitive impairment was reported in 22% but falls, a feature in older men on these medications, were not reported.
The authors conclude that this approach could prove to be an effective medical strategy to decrease attrition from AS. It is important to note that quality of life is important in these patients as is the avoidance of side effects. Concern has also been raised in previous prevention trials using androgen modulating agents with regard to selecting for more aggressive cancers (5).
Can Apalutamide be used in AS patients that have these slow growing tumors? — yes. Should it be is an unclear question. Ultimately, it will be important to involve patients in the design of future trials, as they can help inform the investigators regarding the balance between quality of life, drug side-effects, and cancer progression.
Reference
1. Jarrard D, Filon M, Huang W, Havighurst T, DeShong K, Kim K, Konety BR, Saltzstein D, Mukhtar H, Wollmer B, Suen C, House MG, Parnes HL, Bailey HH. A phase II randomized placebo-controlled trial of pomegranate fruit extract in men with localized prostate cancer undergoing active surveillance. Prostate. 2020 Oct 23
2. Fleshner NE, Lucia MS, Egerdie B, et al. Dutasteride in localised prostate cancer management: the REDEEM randomised, double-blind, placebo-controlled trial. Lancet. 2012 Mar 24;379(9821):1103-11
3. Cussenot O, Cornu JN, Drouin SJ, et al. Secondary chemoprevention of localized prostate cancer by short-term androgen deprivation to select indolent tumors suitable for active surveillance: a prospective pilot phase II study. World J Urol. 2014 Apr;32(2):545-50.
4. Schweizer MT, True L, Ellis W, et al. Resetting the active surveillance clock: Apalutamide in lower risk prostate cancer. Presented at: Society of Urologic Oncology 2020 virtual annual meeting, December 3-5. Poster 1.
5. Andriole GL, Bostwick DG, Brawley OW, Gomella LG, Marberger M, Montorsi F, Pettaway CA, Tammela TL, Teloken C, Tindall DJ, Somerville MC, Wilson TH, Fowler IL, Rittmaster RS; REDUCE Study Group. Effect of dutasteride on the risk of prostate cancer. N Engl J Med. 2010 Apr 1;362(13):1192-202.
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