Objectives: To analyze post-androgen depletion (AD) primary tumors to identify markers of treatment failure because AD does not reduce the probability of prostate-specific antigen (PSA) failure after prostatectomy.
Methods: Tumors removed by radical prostatectomy after 3 months of AD from 21 patients were analyzed for gene expression using oligonucleotide arrays. Differences between patients with and without relapse were identified using a conservative significance criteria of a threefold change and delta 0.68, ensuring a false discovery rate of less than 11%.
Results: At 50 months of follow-up, 7 of the 18 evaluable patients developed a biochemical recurrence. Gleason grade, pretherapy PSA level, T stage, and margin status were similar between the two groups. Patients with recurrence had greater post-AD PSA levels than those without recurrence (0.87 versus 0.19 ng/mL; P = 0.042). Gene expression analysis revealed 35 probe sets overexpressed in tumors from patients who relapsed. Among the highest ranked probe sets were PSA and other androgen-responsive genes. Serum PSA values during AD revealed similar findings. After 40 days of AD, the PSA level in those without recurrence was 1.21 ng/mL versus 4.5 ng/mL in those with recurrence (P = 0.0034). Immunohistochemistry of post-AD tumors also demonstrated a high PSA staining intensity in many tumors that recurred relative to those that didn't.
Conclusions: The results of our study show that early recurrence is associated with expression of androgen-responsive genes. Surprisingly, these could be identified as early as 3 months after the initiation of AD therapy. Whether this represents a failure to abrogate androgen receptor mediated signaling with androgen depletion or early reactivation of signaling is under study.