‘The prostate’ in patients with metastatic prostate cancer: to treat or not to treat?

Examining initial treatment and survival among men with metastatic prostate cancer: An analysis from the CaPSURE registry

BACKGROUND

New data is emerging to guide initial treatment of patients with metastatic prostate cancer (CaP). This study utilizes the Cancer of the Prostate Strategic Urologic Research Endeavor registry to evaluate variations in survival based on initial treatment received by men with metastatic disease at diagnosis or after progression.

MATERIALS AND METHODS

Cancer of the Prostate Strategic Urologic Research Endeavor is a national registry of men diagnosed with CaP and managed at 43 community, academic, and Veteran's centers. We examined socio-demographic factors, disease biology, initial and subsequent therapy received, and survival among patients who presented with de novo or recurrent metastatic disease stratified by receipt of initial local therapy vs. combined local and hormonal therapy. The outcome was prostate cancer specific mortality (PCSM). We performed Fine and Gray competing risks regression analysis to evaluate the association between timing of metastasis and PCSM, adjusted for age, initial treatment, and subsequent therapy.

RESULTS

Of the 14,753 patients diagnosed with CaP from 1990 to 2016, 669 (5%) had metastatic disease. Among the examined patients, 303 (45%) had metastatic disease at diagnosis and 366 (55%) progressed to metastatic disease. Overall, 461 (69%) were ≥65 years old, 582 (87%) had Medicare, and 227 (34%) had an annual income < $30,000. Prostate-specific antigen at diagnosis was >20 ng/ml for 342 (51%) patients and biopsy Gleason grade was ≥4 + 3 for 386 (58%) patients. Among patients with metastatic disease at diagnosis, 31 (10%) received initial local therapy and 272 (90%) received initial hormonal therapy. Among patients who progressed to metastatic disease, 239 (65%) received initial local therapy and 127 (35%) received initial systemic hormonal therapy. Among patients with metastatic disease, the multivariate competing risks model, after adjusting for sociodemographics, marital status, diagnosis year, and comorbidities, revealed a significantly lower risk of PCSM among patients with de novo vs. recurrent metastatic disease (Hazard Ratio 0.66 (95% Confidence Interval 0.51, 0.85) P = 0.002). In the stratified analysis, no difference was seen for patients treated with initial hormonal vs. combined local and hormonal therapy.

CONCLUSIONS

In this analysis of a nationwide cohort of men treated for CaP with all types of therapy over 25 years, we observed that among men with metastatic CaP, the risk of PCSM was lower for de novo vs. recurrent metastatic disease. Additionally, no difference was observed based on initial treatment with combined local and hormonal therapy vs. hormonal therapy alone.

Dual inhibition of BRD4 and PI3K by SF2523 suppresses human prostate cancer cell growth in vitro and in vivo

Bromodomain-containing protein 4 (BRD4) and phosphatidylinositol 3-kinase (PI3K) are both key oncogenic proteins in human prostate cancer. In the current study, we examined the anti-prostate cancer cell activity by SF2523, a BRD4 and PI3K dual inhibitor. We showed that SF2523 potently inhibited survival and proliferation of the primary human prostate cancer cells. SF2523 induced profound apoptosis activation in prostate cancer cells. The dual inhibitor was yet non-cytotoxic to the prostate epithelial cells. At the molecular level, SF2523 downregulated BRD4-regulated genes (cyclin D1, c-Myc and androgen receptor) and almost blocked AKT-S6K1 activation in prostate cancer cells. In vivo, SF2523 intraperitoneal administration at the well-tolerated dose inhibited human prostate cancer xenograft growth in severe combined immunodeficient (SCID) mice. BRD4-regulated genes (cyclin D1, c-Myc and androgen receptor) and AKT-S6K1 activation were inhibited in SF2523-treated tumors. Together, dual inhibition of BRD4 and PI3K by SF2523 suppresses human prostate cancer cell growth in vitro and in vivo.