Comparison of Cabergoline Versus Raloxifene Add-On Therapy to Long-Acting Somatostatin Analogue in Patients With Inadequately Controlled Acromegaly: A Randomized Open Label Clinical Trial

Abstract

The present study aimed to evaluate the efficacy of add-on therapy of cabergoline versus raloxifene to long-acting somatostatin analogues (SAs) in patients with inadequately controlled acromegaly. This was a prospective, randomized open label clinical trial. Forty-four patients (22 per group) completed the study; where participants received either cabergoline (3 mg/week) or raloxifene (60 mg twice daily) add-on therapy for 12 weeks in a parallel manner. The primary outcome was the rate of reduction in serum insulin-like growth factor 1 (IGF-1) from baseline. Secondary outcomes comprised normalization of serum IGF-1 for age and sex. Serum IGF-1 was significantly decreased in both the cabergoline (40.3 ± 25.6%, P<.001) and raloxifene (31.5 ± 24.6%, P<.001) groups, with no significant difference between arms ( P>.05). Normalization in serum IGF-1 values occurred in 40.9% of patients who were on cabergoline compared to 45.5% of those receiving raloxifene ( P = .76). The subsequent logistic regression analysis highlighted baseline IGF-1 as a significant predictor of IGF-1 normalization (odds ratio, 0.995; 95% confidence interval, 0.990-0.999; P = .02). Using the receiver operating characteristic (ROC) curve analysis for the entire group, the baseline IGF-1 value of 1.47 the upper limit of normal (ULN) was the best cut-off point to identify patients with normal IGF-1 at the end of the study (sensitivity: 52.6%, specificity: 84.0%, Yoden's index: 0.366). Full biochemical control of acromegaly was achieved in 22.7% of patients in the cabergoline group compared to 13.6% of those in the raloxifene group ( P = .43). Cabergoline and raloxifene add-on therapy could effectively decrease serum IGF-1 level in patients with inadequately controlled acromegaly. The efficacy profiles of both drugs are comparable. DA = dopamine agonist; FBG = fasting blood glucose; GH = growth hormone; IGF1 = insulin-like growth factor-1; IQR = interquartile range; OR = odds ratio; ROC = receiver operating characteristic; SA = somatostatin analogue; SERM = selective estrogen modulator receptor; ULN = upper limit of normal.