Corticosteroids and Prostate Cancer: Friend or Foe?

Glucocorticoid Receptor and β-Catenin Interact in Prostate Cancer Cells and Their Co-Inhibition Attenuates Tumorsphere Formation, Stemness, and Docetaxel Resistance

Therapy resistance hinders the efficacy of anti-androgen therapies and taxane-based chemotherapy for advanced prostate cancer (PCa). Glucocorticoid receptor (GR) signaling mediates resistance to androgen receptor signaling inhibitors (ARSI) and has also been recently implicated in PCa resistance to docetaxel (DTX), suggesting a role in therapy cross-resistance. Like GR, β-catenin is upregulated in metastatic and therapy-resistant tumors and is a crucial regulator of cancer stemness and ARSI resistance. β-catenin interacts with AR to promote PCa progression. Given the structural and functional similarities between AR and GR, we hypothesized that β-catenin also interacts with GR to influence PCa stemness and chemoresistance. As expected, we observed that treatment with the glucocorticoid dexamethasone promotednuclear accumulation of GR and active β-catenin in PCa cells. Co-immunoprecipitation studies showed that GR and β-catenin interact in DTX-resistant and DTX-sensitive PCa cells. Pharmacological co-inhibition of GR and β-catenin, using the GR modulator CORT-108297 and the selective β-catenin inhibitor MSAB, enhanced cytotoxicity in DTX-resistant PCa cells grown in adherent and spheroid cultures and decreased CD44+/CD24- cell populations in tumorspheres. These results indicate that GR and β-catenin influence cell survival, stemness, and tumorsphere formation in DTX-resistant cells. Their co-inhibition could be a promising therapeutic strategy to overcome PCa therapy cross-resistance.

The Effect of Corticosteroids on Prostate Cancer Outcome Following Treatment with Enzalutamide: A Multivariate Analysis of the Phase III AFFIRM Trial

PURPOSE

The clinical impact of concurrent corticosteroid use (CCU) on enzalutamide-treated patients with metastatic castration-resistant prostate cancer (mCRPC) is unknown. We investigated the association of CCU with overall survival (OS), radiographic progression-free survival (rPFS), and time to prostate-specific antigen progression (TTPP) in post-chemotherapy, enzalutamide-treated patients with mCRPC.

PATIENTS AND METHODS

Post hoc analysis of AFFIRM (NCT00974311) with patients (n = 1,199) randomized 2:1 to enzalutamide 160 mg/day or placebo. Treatment group, CCU, and known prognostic factors were evaluated for impact on OS, rPFS, and TTPP using a multivariate Cox proportional hazards model. CCU was defined as "baseline" (use started at baseline) or "on-study" (baseline plus use that was started during the trial).

RESULTS

Enzalutamide significantly improved OS, rPFS, and TTPP independent of baseline CCU but was associated with inferior clinical outcomes when compared with no baseline CCU, including a shorter OS [10.8 months vs. not reached (NR); HR for use vs. no use, 2.13; 95% confidence interval (CI), 1.79-2.54], rPFS (5.2 months vs. 8.0 months; HR, 1.49; 95% CI, 1.29-1.72], and TTPP (4.6 months vs. 5.7 months; HR, 1.50; 95% CI, 1.25-1.81). These findings held in a multivariate analysis adjusting for baseline prognostic factors wherein baseline CCU was independently associated with decreased OS (HR, 1.71; 95% CI, 1.43-2.04; P < 0.0001) and rPFS (HR, 1.28; 95% CI, 1.11-1.48; P = 0.0007).

CONCLUSIONS

Patients with mCRPC benefited from enzalutamide treatment independent of CCU, but CCU was associated with worse baseline prognostic factors and outcomes.

Neutrophil to Lymphocyte Ratio in Castration-Resistant Prostate Cancer Patients Treated With Daily Oral Corticosteroids

BACKGROUND

The neutrophil to lymphocyte ratio (NLR) has been shown to be highly prognostic across many tumor types, and predictive of treatment outcome in advanced prostate cancer, and has been postulated to be an indirect measure of tumor inflammation. We evaluated the effect of low-dose steroids on NLR in men suffering from castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

The NLR was evaluated in a prospective randomized phase II trial that compared prednisolone 5 mg twice daily and dexamethasone 0.5 mg daily administered to 75 chemotherapy and abiraterone/enzalutamide-naive CRPC patients. NLR was examined at baseline (BL), after 6 and 12 weeks of corticosteroid treatment; associations with >50% prostate-specific antigen (PSA) response, duration of response (PSA progression-free interval), and overall survival (OS) were tested using logistic regression and Cox regression analysis.

RESULTS

The median NLR for all evaluable patients was 2.6 at BL; 2.9 at 6 weeks; and 4.0 at 12 weeks. After low-dose corticosteroid initiation, 46 patients had a decline in PSA with 24 confirmed responders. BL NLR (log10) associated with a PSA response (odds ratio, .029, 95% confidence interval [CI], .002-.493; P = .014), and with the extent of the PSA decline (P = .009). A favorable BL NLR (less than median) associated with a 5.5-fold higher odds of a PSA >50% response (95% CI, 1.3-23.9; P = .02). Higher BL NLR (log10) associated with a shorter time to PSA progression (hazard ratio [HR], 9.5; 95% CI, 2.3-39.9; P = .002). In multivariate analysis BL NLR as a discrete variable was independently associated with PSA progression (HR, 3.5; 95% CI, 1.5-8.1; P = .003). NLR at 6 weeks was also associated with duration of benefit; in the favorable NLR category time to PSA progression was 10.8 months, for those who converted to an unfavorable (greater than median) category 4.5 months, and for those remaining in a unfavorable category only 1.5 months (95% CI, 0.5-2.5; P = .003). OS was 33.1 months (95% CI, 24.2-42.0) and 21.9 months (95% CI, 19.3-24.4) for those with an favorable and unfavorable BL NLR, respectively.

CONCLUSION

Treatment-naive CRPC patients with a high BL or during-treatment NLR appear not to benefit from low-dose corticosteroids. The immunological implications of an unfavorable NLR, and whether corticosteroids might drive prostate cancer progression in patients harboring a high NLR, warrant further study.