Estrogen treatment for acromegaly

Diagnosis and Management of Aggressive/Refractory Growth Hormone-Secreting Pituitary Neuroendocrine Tumors

The majority of acromegaly and gigantism are caused by growth hormone-secreting pituitary neuroendocrine tumors (PitNETs). Most cases can be cured or controlled by surgery, medical therapy, and/or radiotherapy. However, a few of these tumors are resistant to traditional therapy and always have a poor prognosis. The title aggressive/refractory is used to differentiate them from pituitary carcinomas. To date, there is no definitive conclusion on how to diagnose aggressive/refractory growth hormone-secreting PitNETs, which may have slowed the process of exploring new therapeutical strategies. We summarized the literature described diagnosis and treatment of the disease. Potential disease markers and prospective therapies were also included.

The Value of ER∝ in the Prognosis of GH- and PRL-Secreting PitNETs: Clinicopathological Correlations

Pituitary neuroendocrine tumors (PitNETs) are divided into multiple histological subtypes, which determine their clinical and biological variable behavior. Despite their benign evolution, in some cases, prolactin (PRL) and growth hormone (GH)-secreting PitNETs may have aggressive behavior. In this study, we investigated the potential predictive role of ER∝, alongside the clinicopathological classification of PitNETs (tumor diameter, tumor type, and tumor grade). A retrospective study was conducted with 32 consecutive cases of PRL- and mixed GH- and PRL-secreting PitNETs (5 patients with prolactinomas and 27 with acromegaly, among them, 7 patients with GH- and PRL- co-secretion) who underwent transsphenoidal intervention. Tumor specimens were histologically and immunohistochemical examined: anterior pituitary hormones, ki-67 labeling index, CAM 5.2, and ER∝; ER∝ expression was correlated with basal PRL levels at diagnosis (rho = 0.60, p < 0.01) and postoperative PRL levels (rho = 0.58, p < 0.001). In our study, the ER∝ intensity score was lower in female patients. Postoperative maximal tumor diameter correlated with Knosp grade (p = 0.02); CAM 5.2 pattern (densely/sparsely granulated/mixed densely and sparsely granulated) was correlated with postoperative PRL level (p = 0.002), and with ki-67 (p < 0.001). The IGF1 level at diagnosis was correlated with the postoperative GH nadir value in the oral glucose tolerance test (OGTT) (rho = 0.52, p < 0.05). Also, basal PRL level at diagnosis was correlated with postoperative tumor diameter (p = 0.63, p < 0.001). At univariate logistic regression, GH nadir in OGTT test at diagnostic, IGF1, gender, and invasion were independent predictors of remission for mixed GH- and PRL-secreting Pit-NETs; ER∝ can be used as a prognostic marker and loss of ER∝ expression should be considered a sign of lower differentiation and a likely indicator of poor prognosis. A sex-related difference can be considered in the evolution and prognosis of these tumors, but further studies are needed to confirm this hypothesis.

Role of Estrogen and Estrogen Receptor in GH-Secreting Adenomas

Acromegaly is a rare disease with several systemic complications that may lead to increased overall morbidity and mortality. Despite several available treatments, ranging from transsphenoidal resection of GH-producing adenomas to different medical therapies, complete hormonal control is not achieved in some cases. Some decades ago, estrogens were first used to treat acromegaly, resulting in a significant decrease in IGF1 levels. However, due to the consequent side effects of the high dose utilized, this treatment was later abandoned. The evidence that estrogens are able to blunt GH activity also derives from the evidence that women with GH deficiency taking oral estro-progestins pills need higher doses of GH replacement therapy. In recent years, the role of estrogens and Selective Estrogens Receptor Modulators (SERMs) in acromegaly treatment has been re-evaluated, especially considering poor control of the disease under first- and second-line medical treatment. In this review, we analyze the state of the art concerning the impact of estrogen and SERMs on the GH/IGF1 axis, focusing on molecular pathways and the possible implications for acromegaly treatment.

Managing Estrogen Therapy in the Pituitary Patient

Growth hormone (GH) regulates metabolic and physical health in the adult human. Because the GH system is regulated by estrogens, therapeutic estrogen compounds are likely to affect metabolic health. Estrogens are available for oral and parenteral use in natural, prodrug, and synthetic formulations including selective estrogen receptor modulators (SERMs). This review covers the pharmacology of estrogen and the effects on GH action to inform judicious use in the pituitary patient. The effects on the GH system are route dependent due to first-pass hepatic metabolism. Oral but not parenteral estrogen compounds inhibit GH action, reducing hepatic insulin-like growth factor-1 (IGF-1) production, protein anabolism, and fat utilization. In patients with GH deficiency, oral estrogen therapy exacerbates the degree of hyposomatotrophism and attenuates the beneficial effects of GH replacement therapy, effects that are greater with contraceptive than replacement doses. Surveys report that less than one-fifth of hypopituitary women are appropriately replaced by a transdermal route and up to half on oral therapy are inappropriately treated with contraceptive steroids. In acromegaly, however, estrogens, especially synthetic formulations of greater potency, reduce IGF-1, improving disease control, an effect also observed in men treated with SERMs. The route-dependent effects and potency of estrogen formulations are important considerations for optimizing the management of hypogonadal patients with pituitary disease, in particular GH deficiency and acromegaly. For hypopituitary women, estrogens should be replaced by a nonoral route. For acromegaly, oral estrogen formulations can be considered as simple adjuvant therapy for disease control.

A prospective study on the efficacy of oral estrogen in female patients with acromegaly

PURPOSE

To evaluate the efficacy and safety of oral estrogen therapy in female patients of childbearing age with uncontrolled acromegaly and to verify the significance of the presence of estrogen receptor α (ER-α) in somatotropinomas.

METHODS

Prospective study in which biochemical and radiological evaluations were performed at baseline and after six months of treatment with an oral formulation of ethinyl-estradiol 0.03 mg and levonorgestrel 0.15 mg. ER-α was assessed by immunohistochemistry and immunopositivity was considered when it was present in ≥ 1% of cells.

RESULTS

Eight patients with uncontrolled acromegaly were selected. All patients underwent surgery. Four patients were on octreotide LAR 30 mg, two patients were on lanreotide autogel 120 mg, and two patients had active disease after surgery. At the end of follow-up, IGF-I normalized in 3/8 (37%), 2/8 (25%) patients presented with mean IGF-I reduction of 25% but without IGF-I normalization, and 2/8 (25%) did not respond-one had a 13% increase in IGF-I and IGF-I level remained unchanged after treatment in the other. In one patient, treatment was discontinued after 3 months due to side effects (headache), with an IGF-I reduction of 28% but without normalization. Tumor volume increase (41%) was observed in only one patient (the only tumor with positive ER-α expression).

CONCLUSIONS

In uncontrolled patients with acromegaly, a trial with oral estrogen can be an option for young women. Oral estrogen was well tolerated, but the somatotropinoma that presented ER-α expression was the only somatotropinoma that presented growth during treatment.

Associations of GNAS Mutations with Surgical Outcomes in Patients with Growth Hormone-Secreting Pituitary Adenoma

BACKGROUND

The guanine nucleotide-binding protein, alpha stimulating (GNAS) gene has been associated with growth hormone (GH)-secreting pituitary adenoma. We investigated the prevalence of GNAS mutations in Korean patients with acromegaly and assessed whether mutation status correlated with biochemical or clinical characteristics.

METHODS

We studied 126 patients with acromegaly who underwent surgery between 2005 and 2014 at Severance Hospital. We performed GNAS gene analysis and evaluated age, sex, hormone levels, postoperative biochemical remission, and immunohistochemical staining results of the tumor.

RESULTS

GNAS mutations were present in 75 patients (59.5%). Patients with and without GNAS mutations showed similar age distribution and Knosp classification. The proportion of female patients was 76.5% and 48.0% in the GNAS-negative and GNAS-mutation groups, respectively (P=0.006). In immunohistochemical staining, the GNAS-mutation group showed higher GH expression in pituitary tumor tissues than the mutation-negative group (98.7% vs. 92.2%, P=0.015). Patients with GNAS mutations had higher preoperative insulin-like growth factor-1 levels (791.3 ng/mL vs. 697.0 ng/mL, P=0.045) and lower immediate postoperative basal (0.9 ng/mL vs. 1.0 ng/mL, P=0.191) and nadir GH levels (0.3 ng/mL vs. 0.6 ng/mL, P=0.012) in oral glucose tolerance tests. Finally, the GNAS-mutation group showed significantly higher surgical remission rates than the mutation-negative group, both at 1 week and 6 months after surgical resection (70.7% vs. 54.9%, P=0.011; 85.3% vs. 82.4%, P=0.007, respectively).

CONCLUSION

GNAS mutations in GH-secreting pituitary tumors are associated with higher preoperative insulin-like growth factor-1 levels and surgical remission rates and lower immediate postoperative nadir GH levels. Thus, GNAS mutation status can predict surgical responsiveness in patients with acromegaly.

Cycle day 2 insulin-like growth factor-1 serum levels as a prognostic tool to predict controlled ovarian hyperstimulation outcomes in poor responders

OBJECTIVE

To study whether patients exhibiting poor ovarian response have abnormal levels of serum insulin-like growth factor (IGF)-1 on cycle day 2 when compared with age-matched normal and high responders.

DESIGN

Retrospective cohort.

SETTING

University-based practice.

PATIENT(S)

All women between the ages of 21 and 42 years who underwent in vitro fertilization treatment cycle without estrogen pretreatment at our institution between 2013 and 2015.

INTERVENTION(S)

Patients were separated into three groups: poor responders (≤4 oocytes retrieved/cycle cancellation), normal responders (8-12 oocytes), and high responders (≥18 oocytes). Subanalysis focused on the next cycle for poor responders adjacent to the nonpretreated index cycle, in which estrogen pretreatment was implemented.

MAIN OUTCOME MEASURE(S)

Serum cycle day 2: IGF-1, insulin-like growth factor-binding protein (IGFBP)-3 levels, and IGF-1:IGFBP3 ratio, number of eggs retrieved, number of two pronuclei embryos, cumulative pregnancy rate, and live birth.

RESULT(S)

A total of 184 patients met the inclusion criteria. The poor responder group exhibited a more than twofold increase in the cycle day IGF-1 serum levels when compared with normal responders and a threefold increase when compared with the high responders. Cycle day 2 IGF-1 level >72 ng/mL in poor responders had 70% sensitivity and 78% specificity for a negative controlled ovarian hyperstimulation cycle outcome with an area under the curve of 0.83. Luteal estrogen pretreatment in the poor responder group was associated with a significant reduction in IGF-1 levels. Significantly, more retrieved and mature oocytes, as well as two pronuclei embryos, were achieved in the pretreated poor responder group when compared with the yield from their adjacent nonpretreated index cycles. Furthermore, cumulative rates were higher for intrauterine pregnancies, and lower for negative pregnancy outcome.

CONCLUSION(S)

Patients who respond poorly to controlled ovarian stimulation, despite normal cycle day 2 follicle-stimulating hormone levels, have significantly higher serum cycle day 2 IGF-1 levels when compared with age-matched normal and high responders. Cycle day 2 IGF-1 level >72 ng/mL in poor responders was predictive of a negative cycle outcome. Luteal estrogen pretreatment in the poor responder group was associated with a significant reduction in IGF-1 levels, improved response to stimulation, and higher cumulative rates for intrauterine pregnancies, and lower for negative pregnancy outcome.

The significance of estrogen receptors in acromegaly: Are they useful as predictors of prognosis and therapy regimen?

OBJECTIVE

In this study, we considered to assess the presence of estrogen receptors (ER) and the expression of estrogen receptor genes (ESR) in the surgical tissue samples of acromegaly patients and the control group patients with nonfunctioning adenoma and their association with disease activity. We also aimed to determine the significance of ER positivity in acromegaly patients and to find out whether it carries a potential to be used as a predictor of prognosis and therapy regimen in the future.

DESIGN

This study was conducted on a total of 67 patients over 18 years of age. The study group consisted of 34 patients with acromegaly and 33 patients with nonfunctioning pituitary adenoma. The pre- and post-operative basal pituitary hormone levels and magnetic resonance images (MRI) of all patients, as well as their remission status of all acromegaly patients were evaluated. Immunohistochemical (IHC) staining procedures for ER-α were performed on surgical tissue samples. Real-time quantitative polymerase chain reaction (RT-qPCR) method was used to determine the levels of ESR1 and ESR2 gene expressions.

RESULTS

We found that IHC staining for ER-α was positive in 31.3% and 45.5% of the patients with acromegaly and nonfunctioning adenoma respectively. There was no statistically significant difference of ER-α positivity, ER-α immunoreactivity score and ESR1/ESR2 gene expression levels among the study groups (p > .05). Nevertheless, the expression of ESR1 gene was found to be 0.26 times more, and the ESR2 gene to be 0.11 times less in the acromegaly group compared to those of the nonfunctioning adenoma group. Additionally, we detected the positivity of ER-α only in acromegaly patients who were in remission. An inverse association was found between the pre-operative insulin-like growth factor-1 (IGF-1) levels and the expressions of ESR1/ESR2 gene in acromegaly patients. So these results indicated that the high ESR1 and ESR2 gene expressions in acromegaly patients are associated to the decrease of pre-operative IGF-1 values. Also an inverse association was found between the pre-operative adenoma volume and ESR1 Ct values, means that increase in ESR1 gene expression is associated to the decrease of adenoma volume.

CONCLUSIONS

The current results may suggest the use of these parameters as useful prognostic markers because all ER-positive acromegaly patients were in remission and the high ESR1 and ESR2 gene expressions in acromegaly patients is associated to the decrease of pre-operative IGF-1 values. Our results need to be supported by further studies.

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.

Estrogens and selective estrogen receptor modulators in acromegaly

Despite recent advances in acromegaly treatment by surgery, drugs, and radiotherapy, hormonal control is still not achieved by some patients. The impairment of IGF-1 generation by estrogens in growth hormone deficient patients is well known. Patients on oral estrogens need higher growth hormone doses in order to achieve normal IGF-1 values. In the past, estrogens were one of the first drugs used to treat acromegaly. Nevertheless, due to the high doses used and the obvious side effects in male patients, this strategy was sidelined with the development of more specific drugs, as somatostatin receptor ligands and dopamine agonists. In the last 15 years, the antagonist of growth hormone receptor became available, making possible IGF-1 control of the majority of patients on this particular drug. However, due to its high cost, pegvisomant is still not available in many centers around the world. In this setting, the effect of estrogens and also of selective estrogen receptor modulators on IGF-1 control was reviewed, and proved to be an ancillary tool in the management of acromegaly. This review describes data concerning their efficacy and place in the treatment algorithm of acromegaly.

IGF-I levels reflect hypopituitarism severity in adults with pituitary dysfunction

PURPOSE

To evaluate the utility of Insulin-like growth factor I (IGF-I) standard deviation score (SDS) as a surrogate marker of severity of hypopituitarism in adults with pituitary pathology.

METHODS

We performed a retrospective data analysis, including 269 consecutive patients with pituitary disease attending a tertiary endocrine clinic in 1990-2015. The medical files were reviewed for the complete pituitary hormone profile, including IGF-I, and clinical data. Age-adjusted assay reference ranges of IGF-I were used to calculate IGF-I SDS for each patient. The main outcome measures were positive and negative predictive values of low and high IGF-I SDS, respectively, for the various pituitary hormone deficiencies.

RESULTS

IGF-I SDS correlated negatively with the number of altered pituitary axes (p < 0.001). Gonadotropin was affected in 76.6 % of cases, followed by thyrotropin (58.4 %), corticotropin (49.1 %), and prolactin (22.7 %). Positive and negative predictive values yielded a clear trend for the probability of low/high IGF-I SDS for all affected pituitary axes. Rates of diabetes insipidus correlated with IGF-I SDS values both for the full study population, and specifically for patients with non-functioning pituitary adenomas.

CONCLUSIONS

IGF-I SDS can be used to evaluate the somatotroph function, as a valid substitute to absolute IGF-I levels. Moreover, IGF-I SDS predicted the extent of hypopituitarism in adults with pituitary disease, and thus can serve as a marker of hypopituitarism severity.

Gender dependence of serum soluble Klotho in acromegaly

OBJECTIVES

In acromegaly, disease activity is biochemically assessed by growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels. However, they are often discrepant, as several factors including gender influence their relationship. We recently found excessively high serum levels of soluble Klotho (sKl) in acromegalic patients, which depended on GH to a comparable extent as IGF-1. To further elucidate the relationship between GH and sKl, we examined the effect of gender on sKl in patients with untreated acromegaly.

PATIENTS AND DESIGN

We determined GH, IGF-1 and sKl in sera of 62 consecutive patients with newly diagnosed acromegaly (31 females/31 males, aged 20-85 years).

RESULTS

For their given GH excess at presentation with acromegaly, females had lower IGF-1 (490 ± 33 vs 604 ± 33 ng/ml, P = 0·02), but higher sKl [5171 ± 590 vs 3439 ± 431 pg/ml (mean ± SE), P = 0·02] levels than males. In multiple regression analysis, IGF-1 was closely associated with logGH (estimate 139, SE 47, P = 0·005) and BMI (estimate 14·2, SE 4·8, P = 0·005). sKl was closely associated with logGH (estimate 3088, SE 652, P = 0·0001) and gender (estimate 2034, SE 612, P = 0·002), and to a lesser extent with BMI (estimate 174, SE 66, P = 0·01).

CONCLUSIONS

For a given GH status, sKl concentrations are higher and IGF-1 concentrations are lower in women than in men. GH is the strongest predictor for both sKl and IGF-1, but gender needs to be considered when using these parameters for monitoring acromegalic patients.

Estrogen and selective estrogen receptor modulators (SERMs) for the treatment of acromegaly: a meta-analysis of published observational studies

Estrogen and selective estrogen receptor modulator (SERM) treatments for acromegaly have received limited attention since the development of newer pharmacologic therapies. There has been ongoing research evidence suggesting their utility in the biochemical control of acromegaly. Therefore, the aim of this meta-analysis was to synthesise current evidence with a view to determining to what extent and in which acromegalic patient subsets do estrogen and SERMs reduce IGF-1 levels. A literature search was conducted (finished December 2012), which included all studies pertaining to estrogen or SERM treatment and IGF-1. Seven patient subsets were identified from six published observational studies, and were pooled using meta-analytic methods. Overall, the pooled mean loss in IGF-1 was -29.09 nmol/L (95 % CI -37.23 to -20.95). A sensitivity analysis indicated that women receiving estrogen had a substantially greater reduction in IGF-1 levels compared with women receiving SERMs, with a weighted mean loss in IGF-1 of -38.12 nmol/L (95 % CI -46.78 to -29.45) compared with -22.91 nmol/L (95 % CI -32.73 to -13.09). There was a trend that did not reach statistical significance for men receiving SERM treatment at -11.41 nmol/L (95 % CI -30.14 to 7.31). It was concluded that estrogen and SERMs are a low cost and effective treatment to achieve control of IGF-1 levels in acromegalic women either as concomitant treatment for refractory disease, or where access to conventional therapy is restricted. Their use in men requires further study.

Acromegaly and pregnancy: a prospective study

CONTEXT AND OBJECTIVE

The interaction between pregnancy and acromegaly has been studied only retrospectively. We used prospective data to assess those interactions.

DESIGN

Prospective, interventional, multicentric study.

PATIENTS

TEN PREGNANCIES IN EIGHT ACROMEGALIC PATIENTS WERE INCLUDED ACCORDING TO THE FOLLOWING CRITERIA: previous diagnosis of acromegaly; and active acromegaly before pregnancy. Sellar magnetic resonance image (MRI), GH, and IGF1 measurements were carried out before pregnancy. The exclusion criterion was radiotherapy.

INTERVENTION

Withdrawal of pharmacological treatment (octreotide and/or cabergoline and/or pegvisomant) following pregnancy diagnosis.

MAIN OUTCOME MEASURES

Clinical/biochemical evaluations throughout pregnancy/puerperium and sellar MRI after delivery; and GH and IGF1 measurements before pregnancy. GH was measured by an interference-free IFMA assay during pregnancy and IGF1 by measured by Immulite 2000 assay in patients and 64 control pregnancies.

RESULTS

No tumor growth was observed. Nine deliveries were at term and one at 35 weeks (preeclampsia). All newborns were healthy. Mean IGF1 levels before and during pregnancy were similar, but increased significantly during puerperium. As IGF1 in controls increased after midgestation, the prevalence of controlled IGF1 rose significantly from 2/10 (<20 weeks) to 9/10 (>30 weeks). Diabetes mellitus and hypertension/preeclampsia developed in one patient in each group; both complications were nonsignificantly (P=0.06) associated with IGF1 >1.3 ULN before pregnancy.

CONCLUSIONS

Acromegaly control usually improved and tumor growth was not stimulated during pregnancy in spite of withdrawal of drug treatment. Drug treatment can be discontinued in most patients. Uncontrolled disease before pregnancy may pose a higher risk for diabetes and hypertension.

A practical approach to acromegaly management in Latin America

INTRODUCTION

Evidence-based treatment guidelines have undoubtedly advanced medical practice and supported optimal management of acromegaly, but their application may be hampered by limited access to the latest treatment options.

METHODS

In this retrospective, narrative review, the authors revisited existing treatment guidelines for acromegaly in Latin America. These were considered in conjunction with published evidence chosen at the authors' discretion.

FINDINGS

In a socially and economically diverse region, such as Latin America, any regional practice guidelines need to appreciate that recommended treatment options, such as surgery by expert pituitary surgical teams and drug therapies, especially somatostatin analogs, are often not available due to limited resources. In these instances, physicians may be obliged to apply less effective therapeutic options.

CONCLUSIONS

The current article looks at the practical aspects of acromegaly management in Latin America and discusses this in the context of existing guidelines. Furthermore, we consider potential strategies to make better use of resources through combination and multimodal approaches to treatment.

The role of combination medical therapy in acromegaly: hope for the nonresponsive patient

PURPOSE OF REVIEW

This review focuses on combination drug treatment for acromegaly patients, including novel concepts and experimental therapies, with an emphasis on the author's personal experience.

RECENT FINDINGS

A review of published clinical studies demonstrates that combination therapy; somatostatin receptor ligands and dopamine agonists, somatostatin receptor ligands and pegvisomant, or cabergoline and pegvisomant could provide significant additive biochemical control of acromegaly in patients inadequately controlled with conventional somatostatin receptor ligand therapy.

SUMMARY

Advances in combination medical therapy have opened up new perspectives for acromegaly patients who are poorly, or nonresponsive to, presently available single drug therapies.

The place of medical treatment of acromegaly: current status and perspectives

INTRODUCTION

Acromegaly is characterized by elevated growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels and by progressive somatic disfigurement and systemic manifestations, which lead to a mortality rate higher than the general population. Therefore, diagnosis and properly treatment should be performed as soon as possible.

AREAS COVERED

This article focuses on the state of the art of acromegaly medical treatment. Somatostatin analogs, dopamine agonists and GH receptor antagonist were reviewed. Somatostatin analogs, the first-choice pharmacotherapy, can be used as primary or pre-operative treatment or as secondary therapy after failed surgery. Dopamine agonists have been used in patients with slightly elevated hormone levels and/or mixed GH/prolactin adenomas. Pegvisomant is indicated for resistant to somatostatin analogs/dopamine agonists. Combined treatment is also an option for resistant cases. Other non-conventional therapies and perspectives of treatment were also been discussed.

EXPERT OPINION

The control of disease activity in acromegaly is of paramount importance. Medical treatment is an important option for cases in which surgery was unsuccessful or not indicated. Despite the achievements in medical treatment, somatotropic tumor aggressiveness and/or resistance to the drugs currently available remain a concern. Therefore, novel therapy targets based on molecular pathogenesis of GH-secreting tumors are currently in development, aiming at fulfilling this important gap.