PTEN loss is not a determinant of time to castration-resistance following androgen-deprivation therapy in prostate cancer: a study from Jordan

Androgen deprivation therapy (ADT) remains the principal treatment of advanced prostate cancer. However, most patients eventually experience treatment failure, resulting in castrate-resistant prostate cancer (CRPC). Loss of the tumor suppressor gene phosphatase and tensin homolog (PTEN) has been linked to poor survival in prostate cancer. We have recently shown that PTEN loss is evident in approximately 60% of prostate cancer cases in Jordan. However, the correlation between PTEN loss and response to ADT remains unclear. This study aimed to determine the relationship between PTEN loss and time to CRPC in Jordan. We conducted a retrospective analysis of confirmed CRPC cases at our institution from 2005 to 2019 (N=104). PTEN expression was assessed using immunohistochemistry. Time to CRPC was calculated from the initiation of ADT to the confirmed diagnosis of CRPC. Combination/sequential ADT was defined as the use of two or more classes of ADT concomitantly or switching from one class to another. We found that PTEN loss was evident in 60.6% of CRPC. Mean time to CRPC was not different between patients with PTEN loss (24.8 months) and those with intact PTEN (24.2 months; p=0.9). However, patients receiving combination/sequential ADT had a significantly delayed onset of CRPC compared to patients on monotherapy ADT (log-rank Mantel-Cox p=0.000). In conclusion, PTEN loss is not a major determinant of time to CRPC in Jordan. The use of combination/sequential ADT procures a significant therapeutic advantage over monotherapy regimens, delaying the onset of CRPC.

PTEN Loss in a Prostate Cancer Cohort From Jordan

Deletion of phosphatase and tensin homolog (PTEN) in prostate cancer has been associated with early biochemical recurrence, increased metastatic potential, and androgen independence. We evaluated the status of PTEN loss in a cohort of prostate cancer patients from Jordan. We investigated 71 patients with prostate cancer and 52 control subjects with benign prostatic hyperplasia (BPH). PTEN status was assessed by immunohistochemistry. PTEN mutations on exons 1, 2, 5, and 8 were also evaluated by polymerase chain reaction single-stranded conformation polymorphism (PCR-SSCP). We found PTEN loss in 42 of 71 (59.2%) evaluated prostate cancer cases by immunohistochemistry. In contrast, 51 of 52 BPH (98.1%) cases had an intact PTEN. In a subset of 24 prostate cancer cases evaluated by PCR-SSCP, we found PTEN mutations in 15 (62.5%) cases, whereas 22 (91.7%) of BPH controls lacked PTEN mutations. Exon 5 was the most frequently mutated exon (37.5%). Although the loss of PTEN was not significantly correlated with the Gleason Score (GS) or the World Health Organization (WHO)-International Society of Urological Pathology (ISUP) Grade Group (GG), we found higher frequency of PTEN loss (64%) in patients with GS≥4+3/GG≥3, compared with patients with GS≤3+4/GG≤2 (47.6%). In this first study to address the question of PTEN loss in a predominantly Arab population, we documented the frequency of PTEN loss in prostate cancer patients from Jordan, which was found to be higher than in comparable cohorts from East Asia, and was at the higher end of the range of reported frequency of PTEN loss in respective cohorts from North America and Western Europe. Although there was more frequent PTEN loss in cancers with higher GS/GG, this was not statistically significant.