e592 Background: Prostate cancer patients receive androgen deprivation therapy (ADT) to suppress testosterone (T) to prevent proliferation of cancer cells. T suppression levels achieved by bilateral orchiectomy remain the gold standard for the target of suppression by ADT. Although the historical threshold definition of castration is T ≤ 50 ng/dL, increasing evidence suggests T lower than 20ng/dL may improve clinical outcomes, e.g., an increased cancer specific survival and delayed disease progression. To determine the minimal threshold of serum leuprolide required to maintain castrate level T suppression in prostate cancer patients, data from 4 pivotal trials evaluating long-acting, subcutaneously (SC) administered leuprolide acetate (LA) formulated with a biodegradable polymer were pooled. Methods: 438 eugonadal prostate cancer patients (age 40-86) were treated with SC-LA at 7.5, 22.5, 30, or 45mg delivered with a single dose lasting over 1, 3, 4, or 6 months (n = 120, 117, 90, 111), respectively in 4 open-label, fixed-dose, pivotal trials. Descriptive statistics were used to summarize the median concentration of leuprolide acetate at each time point as well as to determine level of T suppression. Results: Over the dosing intervals of the 1, 3, 4 and 6-month SC-LA formulations, median serum leuprolide levels were consistent and median serum T remained below T < 20 ng/dL. In the pooled analysis (n = 86), 99% of patients with LA ≥ 0.1 ng/mL after injection achieved castration after 4 Weeks. Conclusions: These data suggest that SC-LA achieves consistent and prolonged drug delivery resulting in sufficient serum LA levels to provide favorable T suppression below 20 ng/dL, which may have clinical outcomes, e.g., increased cancer specific and progression free survival.
Erratum to hormonal manipulation in androgen signaling: a narrative review on using novel androgen therapy agents to optimize clinical outcomes and minimize side effects for prostate cancer patients
