The efficacy of medical treatment in patients with acromegaly in clinical practice

Pilot study assessing the use of cabergoline for the treatment of cats with hypersomatotropism and diabetes mellitus

OBJECTIVES

An affordable and effective treatment is needed to manage feline hypersomatotropism. The aim of this study was to assess whether treatment with oral cabergoline for 90 days in cats with hypersomatotropism and diabetes mellitus improved diabetic and insulin-like growth factor 1 (IGF-1) control.

METHODS

This was a prospective cohort non-blinded pilot study enrolling client-owned cats with spontaneously occurring diabetes mellitus and hypersomatotropism. Cats received oral cabergoline (5-10 µg/kg q24h) for 90 consecutive days. Serum IGF-1 and fructosamine concentrations were measured on days 1, 30 and 90. Quality of life was determined using the DIAQoL-pet questionnaire on days 1 and 90.

RESULTS

Nine cats were enrolled and eight completed the study. There was no significant change in the following: IGF-1 (day 1 median 2001 ng/ml [range 890-2001 ng/ml]; day 30 median 2001 ng/ml [range 929-2001 ng/ml]; day 90 median 1828 ng/ml [range 1035-2001 ng/ml]; χ2(2) = 0.667, P = 0.805); fructosamine (day 1 median 499 µmol/l [range 330-887 µmol/l], day 30 median 551 µmol/l [range 288-722 µmol/l], day 90 median 503 [range 315-851 µmol/l]; χ2(2) = 0.581, P = 0.764); or DIAQoL-pet score (median on day 1 -2.79 [range -4.62 to -0.28], median on day 90 -3.24 [range -4.41 to -0.28]; P = 0.715). There was a significant change of insulin dose (χ2(2) = 8.667, P = 0.008) with cats receiving higher insulin doses at day 90 compared with day 1 (median on day 1 was 0.98 [range 0.63-1.49] and median on day 90 was 1.56 [range 0.49-2.55] units/kg q12h; P = 0.026).

CONCLUSIONS AND RELEVANCE

Cabergoline did not improve diabetic control or normalise insulin-like growth factor concentration, or improve patient quality of life.

Medical Treatment Landscape for Active Acromegaly in A Pituitary Center in Israel

OBJECTIVE

To evaluate current real-life experience with medical treatment for active acromegaly in a large cohort.

METHODS

Data on demographic parameters, blood tests, imaging studies, and treatments were extracted from the medical records.

RESULTS

The cohort included 87 patients (43 male) with active acromegaly. The mean age at diagnosis was 40.2±11.4 years, and the mean duration of follow-up was 7.9±5.8 years. Seventy patients presented with a macroadenoma. Mean baseline insulin growth factor 1 (IGF-1) (n = 67) was 3.2±1.9 × upper limit of normal (ULN). Surgery and radiotherapy were performed in 75 and 10 patients, respectively. Currently, 38 subjects receive somatostatin analogues, pegvisomant as a monotherapy is given to 8 patients, pasireotide is given to 17 patients, cabegoline to 4 patients, estrogen to 2 females, and SSAs combined with pegvisomant to 10 patients. Eight patients are not being actively treated, including 4 following radiotherapy. Good biochemical control (IGF-1 <1.3 × ULN) was achieved in 76 patients (87%), and 11 patients (13%) are currently uncontrolled (IGF-1 >1.3 × ULN). Seventy-eight percent of controlled patients are being given 1 medication; 11% are on combination therapy; 4 patients are well controlled after radiotherapy and 2 are partially controlled without any treatment. The main adverse effects of treatment were diabetes mellitus in 7 patients (on pasireotide) and symptomatic cholelithiasis in 5 patients.

CONCLUSION

Active acromegaly can be controlled medically in most patients, with a low rate of adverse effects. This study displays the characteristic variety of treatment options available for active acromegaly.

OATP1A2 and OATP2B1 Are Interacting with Dopamine-Receptor Agonists and Antagonists

Interaction with the dopaminergic system in the central nervous system is either therapeutically intended or it is a side effect. In both cases, dopamine-receptor agonists (DRA) like the ergoline derivative bromocriptine and dopamine-receptor antagonists (DRAn) like metoclopramide have to cross the blood-brain barrier (BBB). The organic anion transporting polypeptides (OATP) 1A2 and 2B1 are cellular uptake carriers for a variety of endogenous and xenobiotic compounds. As both transporters are expressed in endothelial cells of the BBB, the aim of the present study was to determine whether the DRA bromocriptine, cabergoline, and pergolide and the DRAn metoclopramide and domperidone are interacting with OATP1A2 and 2B1 and could therefore be candidate genes modifying wanted and unwanted effects of these drugs. Localization of both transporters in the brain was confirmed using LC-MS/MS and immunofluorescence stainings. For the functional studies, MDCKII cells stably expressing OATP1A2 or 2B1 were used. Initial interaction studies with the well-characterized transporter substrate estrone 3-sulfate revealed that all tested compounds except pergolide inhibit the transport function of both proteins with the most potent effect for bromocriptine (IC₅₀ = 2.2 μM (OATP1A2) and IC₅₀ = 2.5 μM (OATP2B1)). Further studies using the indirect competitive counterflow method identified bromocriptine, cabergoline, and domperidone as substrates of both transporters, whereas metoclopramide was only transported by OATP1A2. These findings were verified for domperidone by direct measurements using its tritium-labeled form as a tracer. Moreover, the transporter-mediated uptake of this compound was sensitive to the OATP1A2 and OATP2B1 inhibitor naringin. In conclusion, this study suggests that OATP1A2 and 2B1 may play a role in the uptake of DR agonists and antagonists into the brain.

Treatment of Pituitary and Other Tumours with Cabergoline: New Mechanisms and Potential Broader Applications

Cabergoline is a dopamine agonist that has been used as the first-line treatment option for prolactin-secreting pituitary adenomas for several decades. It not only suppresses hormone production from these prolactinomas, but also causes tumour shrinkage. Recent studies revealed some novel mechanisms by which cabergoline suppresses tumour cell proliferation and induces cell death. In this article, we review the most recent findings in cabergoline studies, focusing on its anti-tumour function. These studies suggest the potential broader clinical use of cabergoline in the treatment of other tumours such as breast cancer, pancreatic neuroendocrine tumours, and lung cancer.

Evaluation of upper gastrointestinal system in acromegaly

PURPOSE

Acromegaly causes multiple comorbidities, including gastrointestinal disorders. The present study evaluated the frequency of hiatal hernia and other upper gastrointestinal pathologies in patients with acromegaly, given that visceromegaly and reduced nitric oxide levels in acromegaly may impact diaphragm and lower esophageal sphincter function and thus possibly the development of hiatal hernia.

METHODS

Thirty-nine acromegaly patients followed our center for the previous 6months were recruited. Upper gastrointestinal endoscopy was performed once in all patients to evaluate hiatal hernia, esophagitis, gastroduodenitis and ulcer.

RESULTS

Twenty-three patients were male and 16 female. Upper gastrointestinal endoscopy found hiatal hernia, esophagitis and gastroduodenitis or gastric ulcer in 3 (7.6%), 2 (1.7%) and 31 (79.4%) patients, respectively. Pathologic examination of gastric antrum biopsy found intestinal metaplasia in 12 (30.7%) patients, and Helicobacter pylori was positive in 13 (33.3%). There were no significant correlations between age, gender, disease duration or preoperative adenoma size on the one hand and hiatal hernia or other endoscopic findings on the other. Similarly, neither surgical success nor recurrence was associated with endoscopic findings.

CONCLUSIONS

The study showed that prevalence of gastritis, duodenitis, peptic ulcer and intestinal metaplasia is higher and prevalence of hiatal hernia lower in acromegaly patients than in the healthy population. Various unknown disease-related pathophysiological conditions may play a role; there is a need for further studies.

Systemic Complications of Acromegaly and the Impact of the Current Treatment Landscape: An Update

Acromegaly is a chronic systemic disease with many complications and is associated with increased mortality when not adequately treated. Substantial advances in acromegaly treatment, as well as in the treatment of many of its complications, mainly diabetes mellitus, heart failure, and arterial hypertension, were achieved in the last decades. These developments allowed change in both prevalence and severity of some acromegaly complications and furthermore resulted in a reduction of mortality. Currently, mortality seems to be similar to the general population in adequately treated patients with acromegaly. In this review, we update the knowledge in complications of acromegaly and detail the effects of different acromegaly treatment options on these complications. Incidence of mortality, its correlation with GH (cumulative exposure vs last value), and IGF-I levels and the shift in the main cause of mortality in patients with acromegaly are also addressed.

How are growth hormone and insulin-like growth factor-1 reported as markers for drug effectiveness in clinical acromegaly research? A comprehensive methodologic review

OBJECTIVE

In rare disease research, most randomized prospective clinical trials can only use limited number of patients and are comprised of highly heterogeneous populations. Therefore, it is crucial to report the results in such a manner that it allows for comparison of treatment effectiveness and biochemical control between studies. The aim of this review was to investigate the current methods that are being applied to measure and report growth hormone (GH) and insulin-like growth factor-1 (IGF-1) as markers for drug effectiveness in clinical acromegaly research.

SEARCH STRATEGY

A systematic search of recent prospective and retrospective studies, published between 2012 and 2017, that studied the effects of somatostatin analogues or dopamine agonists in acromegaly patients was performed. The markers of interest were GH, IGF-1, and the suppression of GH after an oral glucose tolerance test (OGTT). Additionally, the use of pharmacokinetic (PK) measurements in these studies was analyzed. The sampling design, cut-off for biochemical control, reported units, and used summary statistics were summarized.

RESULTS

A total of 49 articles were selected out of the 263 screened abstracts. IGF-1 concentrations were measured in all 49 studies, GH in 45 studies, and an OGTT was performed in 11 studies. A wide range of different cut-off values and sampling designs were used to determine biochemical control in acromegaly patients. The summary statistics were reported in various ways, with the percentage of biochemical control most frequently used. Nine studies sampled the PK at one or more time points. Non-compartmental analyses were commonly performed on the available PK data.

CONCLUSIONS

The way GH and IGF-1 are measured and reported in acromegaly research varies considerably. A consensus on how to report study results would enable better comparisons between studies, thereby improving evidence based decision making to optimize treatment in acromegaly.