New directions in pharmacological treatment of acromegaly

Trends in incidence and mortality risk for acromegaly in Norway: a cohort study

PURPOSE

Recent data have shown a decreasing overall mortality in acromegaly over the last decades. However, cancer incidence and cancer-related mortality still appear to be increased. Our aim was to obtain updated epidemiological data from Norway in a clinically well-defined cohort with complete register-based follow-up.

METHODS

Patients diagnosed with acromegaly from South-Eastern Norway between 1999-2019 (n = 262) and age and sex matched population controls (1:100) were included (n = 26,200). Mortality and cancer data were obtained from the Norwegian Cause of Death and Cancer Registry. Mortality and cancer incidence were compared by Kaplan-Meier analyses and Cox regression; we report hazard ratios (HRs) with 95% confidence intervals (95% CI).

RESULTS

Median age at diagnosis was 48.0 years (interquartile range (IQR): 37.6-58.0). Mean annual acromegaly incidence rate was 4.7 (95% CI 4.2-5.3) cases/10⁶ person-years, and the point prevalence (2019) was 83 (95% CI 72.6-93.5) cases/10⁶ persons. Overall mortality was not increased in acromegaly, HR 0.8 (95% CI 0.5-1.4), cancer-specific and cardiovascular-specific mortality was also not increased (HR: 0.7 (95% CI 0.3-1.8) and 0.8 (95% CI: 0.3-2.5) respectively). The HR for all cancers was 1.45 (1.0-2.1; p = 0.052).

CONCLUSION

In this large cohort study, covering the period 1999-2019, patients were treated with individualized multimodal management. Mortality was not increased compared to the general population and comparable with recent registry studies from the Nordic countries and Europe. Overall cancer risk was slightly, but not significantly increased in the patients.

Gene expression profiling of subcutaneous adipose tissue reveals new biomarkers in acromegaly

CONTEXT

Active acromegaly is characterized by lipolysis-induced insulin resistance, which suggests adipose tissue (AT) as a primary driver of metabolic aberrations.

OBJECTIVE

To study the gene expression landscape in AT in patients with acromegaly before and after disease control in order to understand the changes and to identify disease-specific biomarkers.

METHODS

RNA sequencing was performed on paired subcutaneous adipose tissue (SAT) biopsies from six patients with acromegaly at time of diagnosis and after curative surgery. Clustering and pathway analyses were performed in order to identify disease activity-dependent genes. In a larger patient cohort (n = 23), the corresponding proteins were measured in serum by immunoassay. Correlations between growth hormone (GH), insulin-like growth factor I (IGF-I), visceral AT (VAT), SAT, total AT, and serum proteins were analyzed.

RESULTS

743 genes were significantly differentially expressed (P-adjusted < .05) in SAT before and after disease control. The patients clustered according to disease activity. Pathways related to inflammation, cell adhesion and extracellular matrix, GH and insulin signaling, and fatty acid oxidation were differentially expressed.Serum levels of HTRA1, METRNL, S100A8/A9, and PDGFD significantly increased after disease control (P < .05). VAT correlated with HTRA1 (R = 0.73) and S100A8/A9 (R = 0.55) (P < .05 for both).

CONCLUSION

AT in active acromegaly is associated with a gene expression profile of fibrosis and inflammation, which may corroborate the hyper-metabolic state and provide a means for identifying novel biomarkers.

Expression of SSTR2a, but not of SSTRs 1, 3, or 5 in somatotroph adenomas assessed by monoclonal antibodies was reduced by octreotide and correlated with the acute and long-term effects of octreotide

CONTEXT

Reduced expression of somatostatin receptors (SSTRs) in somatotroph adenomas and their potential down-regulation after medical treatment may explain the unsatisfactory response to octreotide in particular acromegalic patients. The expression of SSTRs other than SSTR2a has not been studied in large, unselected cohorts using novel rabbit monoclonal antibodies.

OBJECTIVE

We aimed to determine the expression of SSTRs 1, 2a, 3, and 5 in somatotroph adenomas, to correlate expression with clinical characteristics and the response to octreotide, and to ascertain whether preoperative octreotide treatment affected SSTR expression.

DESIGN, SETTING, PATIENTS

The study included 78 adenomas from patients operated on consecutively during 2000 to 2010. After exclusion of 13 patients, immunohistochemical analysis with rabbit monoclonal antibodies against SSTRs 1, 2a, 3, and 5 (clones UMB-7, -1, -5, and -4) was performed on 65 adenomas.

INTERVENTION

Twenty-eight patients received preoperative octreotide, and 37 patients were operated on without pretreatment. Twenty-six patients were randomized to direct surgery (n = 13) or to octreotide pretreatment (n = 13).

MAIN OUTCOME MEASURE

SSTR expression was evaluated using a 12-grade scoring system. The responses to the octreotide test dose (GH reduction) and to 6 months of octreotide (IGF-I reduction) were measured.

RESULTS

The majority of adenomas showed membranous expression of SSTRs 2a and 5. SSTR2a expression was reduced in the pretreated group and correlated with the acute octreotide test results and the effect of octreotide treatment. In a linear regression model with SSTR2a expression as the determinant, the correlation with the acute test response improved after adjustment for medical pretreatment.

CONCLUSION

Rabbit monoclonal antibodies are reliable markers of SSTRs in somatotroph adenomas. SSTR2a expression correlated with the response to octreotide and was reduced after octreotide treatment, indicating the need for adjustment when SSTR2a expression is correlated with baseline characteristics. Evaluation of SSTR subtypes may be an important aspect of improving the medical treatment for acromegaly.

Intensity of pituitary adenoma on T2-weighted magnetic resonance imaging predicts the response to octreotide treatment in newly diagnosed acromegaly

BACKGROUND

Primary, preoperative medical treatment is an option in selected patients with acromegaly, but a subset of patients respond poorly. Valid prediction of response to somatostatin analogues (SA) might thus alter treatment stratification. The aims of this study were to assess whether T2 signal intensity could determine long-term response to first-line SA treatment and to assess clinical and biochemical baseline characteristics, as well as histological subtype in relation to the magnetic resonance imaging (MRI) appearances.

METHODS

In 45 newly diagnosed patients, T2-weighted signal intensity of the tumour was classified into hypo-, iso- or hyperintense. Biochemical and clinical baseline variables for the three groups were compared. In 25 patients primarily treated with long-acting SA for a median of 6 months [interquartile range (IQR):155-180 days], GH and IGF-1 reduction was assessed, and in 34 cases, immunohistochemical granulation pattern was evaluated.

RESULTS

The results showed that 12 (27%) adenomas were hypointense, 15 (33%) isointense and 18 (40%) hyperintense. Median IGF-1 [ratio IGF-1/ULN; (upper limit of normal)] was 3·5 (2·3-4·9), 2·9 (2·6-3·8) and 1·9 (1·3-2·6), respectively (P = 0·006 for difference between groups). Median GH values (μg/l) of a 3- to 5-point profile were 17·5 (6·1-35), 9·3 (6·0-32·5) and 4·1 (1·5-8·3), (P = 0·025). Median IGF-1 reduction (% of baseline) after first-line SA treatment was 51 (49-70), 36 (19-74) and 13 (5-42) (P = 0·03); median reduction in GH (% of baseline) was 86 (72-94), 78 (62-85) and 46 (1-70) (P = 0·02). T2 hyperintensity was associated with sparse granulation pattern on immunohistochemistry.

CONCLUSION

In patients with acromegaly, T2 signal intensity at diagnosis correlates with histological features and predicts biochemical outcome of first-line SA treatment.

Adenoma granulation pattern correlates with clinical variables and effect of somatostatin analogue treatment in a large series of patients with acromegaly

CONTEXT

Somatotroph adenomas have been classified into densely granulated (DG) and sparsely granulated (SG) tumours with a transitional, intermediate group. Gsp oncogenes are activating mutations in the Gsα subunit gene, found in approximately 40% of somatotroph adenomas.

OBJECTIVES

To explore granulation pattern and presence of gsp oncogene in acromegaly with correlations to clinical and biochemical variables and to the effect of treatment with somatostatin analogues (SA), as well as to describe granulation pattern in adenomas with and without SA pretreatment.

DESIGN/SETTINGS/PATIENTS

Seventy-eight patients with active acromegaly were included. Long-term SA efficacy was evaluated in 29 patients treated preoperatively and in ten treated postoperatively. Granulation pattern was examined, as were immunohistochemical analyses for E-cadherin and SSTR2a. Protein levels of E-cadherin and SSTR2a were measured (Western blot). Gsp mutation analysis was available for 74 adenomas.

RESULTS

DG adenomas and the transitional group had higher serum levels of IGF-1 per tumour volume than SG (P = 0·009; P = 0·005). Acute and long-term SA responses were lower in SG (P = 0·001; P = 0·043). No correlation between gsp mutation and granulation was found, and no difference in granulation pattern according to preoperative SA treatment was demonstrated. A significant correlation between granulation and E-cadherin was found, where SG had lowest immunohistochemical expression, substantiated by protein levels, and a highly significant gradient was observed from DG, through the transitional group, to SG.

CONCLUSIONS

Densely granulated adenomas were highly responsive to somatostatin analogues in contrast to SG adenomas. The transitional group behaved clinically more like DG adenomas. However, based on E-cadherin, a marker of dedifferentiation, the transitional group seemed to be a true intermediate.

Six-month preoperative octreotide treatment in unselected, de novo patients with acromegaly: effect on biochemistry, tumour volume, and postoperative cure

OBJECTIVE

Treatment with somatostatin analogues is the primary medical treatment of acromegaly. Controversies still exist whether acute octreotide effect predicts long-term biochemical effects, tumour regression or surgical cure. This prospective study investigates effect of 6-month treatment with octreotide long-acting repeatable (LAR) on insulin-like growth factor-1 (IGF-1) and growth hormone (GH) levels, pituitary function, tumour regression and postoperative cure in de novo acromegalic patients.

DESIGN AND METHODS

After a baseline evaluation including fasting hormone levels, MRI scan and an acute 50 μg octreotide test, 32 patients were treated with octreotide LAR 20 mg every 28th day for 6 months before surgery. Treatment effects on IGF-1 and GH levels, serum hormone levels and tumour volume were monitored. Surgical cure was evaluated 3 months postoperatively.

RESULTS

Mean tumour volume reduction was 35%, in one-third of the patients more than 50%, while approximately one-third achieved biochemical remission evaluated by normalized IGF-1 levels. The GH reduction following an acute octreotide test was 81 ± 19% and associated with long-term GH reduction (r = 0·78, P < 0·0005). However, neither acute (r = 0·29, P = 0·12) nor the long-term octreotide effect (r = 0·11, P = 0·58) on GH levels was associated with tumour volume reduction and did not predict subsequent surgical cure.

CONCLUSION

Six months of long-acting octreotide using a fixed dose, 1/3 of the patients came in biochemical remission, while 2/3 had significant tumour reduction. Moreover, an acute effect of octreotide seemed to be a prerequisite for long-term effect.

The expression of E-cadherin in somatotroph pituitary adenomas is related to tumor size, invasiveness, and somatostatin analog response

CONTEXT

Appropriate cell-to-cell adhesion is fundamental for the epithelial phenotype of pituitary cells. Loss of the adhesion protein E-cadherin has been associated with invasiveness, metastasis, and poor prognosis in cancers of epithelial origin. In somatotroph adenomas, a variable and reduced expression of E-cadherin has been demonstrated. In addition, nuclear translocation of E-cadherin was found to correlate with pituitary tumor invasion.

OBJECTIVE

The objective was to examine the protein expression of E-cadherin in somatotroph pituitary adenomas in relation to adenoma size, invasiveness, and somatostatin analog (SMS) efficacy.

PATIENTS AND METHODS

Eighty-three patients were included, and 29 were treated preoperatively with SMS. Adenoma E-cadherin protein expression was analyzed by Western blot (61 patients) and immunohistochemistry (IHC) (80 patients) with antibodies directed against both extracellular and intracellular domains (IHC). The acute (direct surgery group) and long-term (preoperatively treated group) SMS responses were evaluated. Baseline tumor volume and invasiveness were measured on magnetic resonance imaging scans.

RESULTS

Membranous E-cadherin was lost in several adenomas. Nine of these were nuclear E-cadherin positive. The E-cadherin protein expression correlated negatively to tumor size and positively to acute SMS response. Low E-cadherin levels (preoperatively treated group only) and loss of membranous E-cadherin correlated to tumor invasiveness. The E-cadherin level correlated positively to tumor reduction after SMS treatment, and adenomas with nuclear E-cadherin staining had lower IGF-I reduction and tumor shrinkage. Preoperatively treated adenomas had reduced E-cadherin protein levels, but the IHC expression was unaltered.

CONCLUSION

Reduced E-cadherin expression may correlate to a dedifferentiated phenotype in the somatotroph pituitary adenomas.