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.