A Phase II, Single Arm, Multicentre Trial of Triamcinolone With a GnRH Analog for Castrate-Resistant Prostate Cancer (TRICREST)

Abstract

BACKGROUND: Corticosteroids are active in castration-resistant prostate cancer (CRPC) by suppression of adrenal androgen production. Triamcinolone is an intramuscular steroid injection which has putative advantages over commonly used steroids, such as dexamethasone and prednisolone. METHODS: This was a multicentre, phase II study of intramuscular triamcinolone administered monthly in patients with chemotherapy-naïve CRPC. 55 patients were recruited from 2012 to 2016. Imaging was performed every 3 months. The primary end point was radiological and symptomatic progression-free survival (PFS). Secondary end points included PSA progression, weight changes, and toxicity. We also conducted an exploratory analysis on steroid androgenic precursors, collected before and 1 month after triamcinolone, to measure correlation to PFS. RESULTS: At a median follow-up time of 18.7 months, the median radiological PFS was 9.4 months (95% confidence interval [CI]: 7.4-20.3 months), and the 6-month radiological PFS rate was 69.1% (95% CI: 55.1%-79.5%). The 50% PSA response rate was 63.6% (95% CI: 49.6-76.2). There were no treatment-related deaths. The most common grade 3 toxicity was hypertension (44%), but only five patients (9%) required concomitant medication. Proximal myopathy was observed in 22 patients (40%). There was no evidence of weight gain (mean weight 83.5 kg pre-study and 79.8 kg post-study). Urinary total androgen metabolites and dehydroepiandrosterone did not predict response to triamcinolone. CONCLUSION: Intramuscular triamcinolone is an effective hormonal agent in CRPC. Its side-effect profile is different from other steroids and has the advantage of supervised administration.