Treatment of acromegaly with SS analogues: should GH and IGF-I target levels be lowered to assert a tight control of the disease?

Mean GH profile is more accurate than single fasting GH in the evaluation of acromegaly disease control during somatostatin receptor ligands therapy

PURPOSE

This study aims to compare the accuracy of mean GH profile (GHP) < 2.5 ng/ml and single fasting GH (SGH) < 1 ng/ml in the evaluation of disease control in acromegaly patients during somatostatin receptor ligands (SRLs) therapy.

METHODS

We retrospectively enrolled 100 acromegaly patients, 68 responder, and 32 partial responder to SRLs. Controlled disease has been defined as IGF-I levels within age-related normal limits, while partial response as pathological IGF-I values despite a reduction ≥ 50%. In all patients, GHP, SGH, IGF-I, and IGFBP-3 were evaluated.

RESULTS

Median GHP levels (1.2 ng/ml, IQR 0.5-2.3 ng/ml) were lower (p = 0.001) than SGH (1.9 ng/ml, IQR 1.0-3.6 ng/ml). Accuracy of GHP was 81%, whereas that of SGH was 55%, with a Kappa index of 0.520 and 0.237, respectively. In multivariable analysis GHP (p = 0.002) and IGFBP-3 (p = 0.004), but not SGH, were independently associated with normal IGF-I levels. At receiver-operator characteristic curve (ROC) analysis GHP cut-off sensitivity and specificity were 94.1% and 50.0%, respectively, while SGH sensitivity and specificity were 35.3% and 93.7%, respectively. Finally, in obese patients the GH cut-off level (both as SGH and GHP) associated to good disease control was significantly different with respect to not obese ones.

CONCLUSIONS

GHP associates with IGF-I (and therefore with appropriate control of disease) with higher accuracy than SGH. When GH evaluation is needed, the measurement of mean GHP should be preferred and use of BMI-related cut-offs is suggested.

Discordant GH and IGF-1 Results in Treated Acromegaly: Impact of GH Cutoffs and Mean Values Assessment

CONTEXT

Discordant growth hormone (GH) and insulin-like growth factor-1 (IGF-1) values are frequent in acromegaly.

OBJECTIVE

To evaluate the impact of different GH cutoffs on discordance rate. To investigate whether the mean of consecutive GH measurements impacts discordance rate when matched to the last available IGF-1 value.

DESIGN

Retrospective study.

SETTING

Referral center for pituitary diseases.

PATIENTS

Ninety acromegaly patients with at least 3 consecutive evaluations for GH and IGF-1 using the same assay in the same laboratory (median follow-up 13 years).

INTERVENTIONS

Multimodal treatment of acromegaly.

MAIN OUTCOME MEASURES

Single fasting GH (GHf) and IGF-1 (IGF-1f). Mean of 3 GH measurements (GHm), collected during consecutive routine patients' evaluations.

RESULTS

At last evaluation GHf values were 1.99 ± 2.79 µg/L and age-adjusted IGF-1f was 0.86 ± 0.44 × upper limit of normality (mean ± SD). The discordance rate using GHf was 52.2% (cutoff 1 µg/L) and 35.6% (cutoff 2.5 µg/L) (P = 0.025). "High GH" discordance was more common for GHf <1.0 µg/L, while "high IGF-1" was predominant for GHf <2.5 µg/L (P < 0.0001). Using GHm mitigated the impact of GH cutoffs on discordance (GHm <1.0 µg/L: 43.3%; GHm <2.5 µg/L: 38.9%; P = 0.265). At receiver-operator characteristic curve (ROC) analysis, both GHf and GHm were poor predictors of IGF-1f normalization (area under the curve [AUC] = 0.611 and AUC = 0.645, respectively). The prevalence of disease-related comorbidities did not significantly differ between controlled, discordant, and active disease patients.

DISCUSSION

GH/IGF-1 discordance strongly depends on GH cutoffs. The use of GHm lessen the impact of GH cutoffs. Measurement of fasting GH levels (both GHf and GHm) is a poor predictor of IGF-1f normalization in our cohort.

Growth hormone receptor exon 3 isoforms may have no importance in the clinical setting of multiethnic Brazilian acromegaly patients

BACKGROUND

Acromegaly is associated with significant morbidity and increased mortality, but has a variable severity phenotype. The presence of the exon 3-deleted isoform of the growth hormone receptor (d3-GHR) may influence the disease phenotype and treatment outcomes, including the frequency of biochemical discordance after medical treatment.

AIMS

The objective of this study was to analyze the influence of the d3-GHR isoform on clinical and biochemical characteristics and in the treatment outcomes of Brazilian multiethnic acromegaly patients.

METHODS

We retrospectively analyzed our acromegaly outpatient clinic databank and collected demographic, clinical, biochemical and treatment outcome data from those patients who agreed to participate in the study. A blood sample was collected from all patients, the DNA was extracted and the GHR isoforms were evaluated by PCR, with the full length (fl)-GHR represented by a 935-bp fragment and the d3-GHR represented by a 532-bp fragment.

RESULTS

A total of 121 patients were included. Fifty-six patients (46.3 %) were full-length homozygous (fl/fl), 48 (39.7 %) were heterozygous (fl/d3) and 17 (14.0 %) were d3-GHR homozygous (d3/d3). There was no difference between patients homozygous for the fl isoform and those harboring at least one d3-GHR allele in the demographic, clinical and biochemical data or in the treatment outcomes, including somatostatin receptor ligands (SRL) monotherapy, combination therapy with SRL and cabergoline and pegvisomant treatment. There was also no difference between the groups for the frequency of GH and IGF-I discordance after medical treatment.

CONCLUSION

GHR exon 3 genotyping appears to have no clinical significance, at least in Brazilian acromegaly patients.

Growth hormone values after an oral glucose load do not add clinically useful information in patients with acromegaly on long-term somatostatin receptor ligand treatment

The optimal method of assessing GH status in acromegalic patients receiving medical therapy with somatostatin analogs (SSA) has been matter of debate. The aim of the study has been to investigate whether OGTT may add information in patients with discordant random GH (GHr) and IGF values. Moreover, we evaluated the association of GH nadir with the prevalence of co-morbidities observed in acromegalic patients on SSA therapy. We evaluated 130 patients with proven diagnosis of acromegaly on SSA. The patients were subdivided in three groups: patients with controlled disease (both safe random GH and normal IGF-I, group A, 20.0 %), patients with uncontrolled disease (both high random GH and IGF-I, group B, 34.6 %), and patients with discordant random GH and IGF-I values (group C, 35.4 %). A high concordance rate for GH nadir with random GH and IGF-I was observed in group B, while a significant reduced concordance rate has been observed in group A (100 % sensitivity, 64.5 % specificity). By contrast, in group C, we observed concordant results between GH nadir and IGF-I only in 14/59 patients. In group A, the prevalence of diabetes was lower than in group B or C. Safe random GH was the only single criteria associated with a lower prevalence of diabetes. Discrepant IGF-I and either GH nadir or random GH values are frequently observed in acromegalic patients treated with SSA. Concordant IGF-I and random GH may influence the prevalence of metabolic complications. GH nadir measurement may help to interpret discrepancies between random GH and IGF-I data only in few cases.

Comparison of two immunoassays in the determination of IGF-I levels and its correlation with oral glucose tolerance test (OGTT) and with clinical symptoms in acromegalic patients

The aim of our study was to evaluate two different methodologies in IGF-I levels determination, its correlation with GH nadir in OGTT <1 and <0.4 ng/ml and with clinical symptoms in acromegalic patients. We analyzed 37 patients. Sixteen patients had not undergone any kind of treatment (Group 1). Twenty-one patients underwent surgery as primary treatment, and after that, some of them another kind of treatment (except pegvisomant) (Group 2). Serum IGF-I levels were measured by Immulite-1000 (IMM) and by an immunoradiometric assay (DSL) and, GH by immunochemiluminometric assay. IGF-I levels by IMM and by DSL showed a significant difference. When we analyzed in both groups the concordance by crosstabs-Kappa coefficients, between different parameters, GH nadir <1 and <0.4 ng/ml with IGF-I by DSL and IMM showed concordance in group 1, but in group 2 only GH nadir <1 and <0.4 ng/ml had a weak concordance with IGF-I by IMM. When we analyzed clinical symptoms in the patients and, GH nadir <1 and <0.4 ng/ml and IGF-I levels by both methodologies, more than 90% of clinically active patients had abnormal GH response or/and elevated IGF-I levels in group 1, but less than 70% in group 2. In the 8 patients under medical treatment, GH nadir was higher than 0.4 ng/ml in all patients, and IGF-I levels were elevated in 8/8 by DSL and in 6/8 by IMM. In conclusion, discrepant GH and IGF-I levels in the diagnosis and follow-up of patients with acromegaly requires consideration of many factors that influence these parameters.

Octreotide long-acting repeatable for acromegaly

Acromegaly remains a therapeutic challenge for the endocrinologist. Among the available therapeutic options, octreotide long-acting repeatable (Sandostatin(®) LAR(®), Novartis) plays a chief role, both as a primary therapy and as an adjuvant treatment after unsuccessful surgery. A plethora of papers and a meta-analysis have demonstrated its efficacy in: control of clinical picture; achievement of safe growth hormone and normal age-matched IGF-I levels (both factors associated with restoration of normal life expectancy) in 60-70% of patients; control of tumor volume (with real shrinkage in over half of cases); and halt or reversal of most acromegaly-associated comorbidities. Treatment is well tolerated in most patients and can be safely prolonged for many years if required.

Assessment of biochemical control of acromegaly during treatment with somatostatin analogues by oral glucose load and insulin-like growth factor I

BACKGROUND

The use of oral glucose tolerance test (OGTT) in evaluating biochemical control in acromegalic patients on somatostatin analogues (SSA) has recently been questioned.

AIM

To gain further insights into this topic, we analyzed basal and nadir GH levels during OGTT in acromegalic patients on SSA.

SUBJECTS AND METHODS

Basal IGF-I and GH values, as well as GH levels along the test, were analyzed in 115 standard OGTT performed in 33 acromegalic patients followed up between 1993 and 2009. All patients were on SSA at the time of the study; 22 of them had previously undergone unsuccessful surgery. No patient had undergone radiotherapy. GH suppression was considered normal when the hormonal value fell to <1 μg/l during OGTT. Diagnostic accuracy was analyzed by receiver operating characteristic (ROC) curves.

RESULTS

ROC analysis showed that the GH basal value yielding the best specificity (100%) was 3.9 μg/l. All patients with basal GH>3.9 μg/l displayed lack of GH suppression after OGTT and 80% also displayed high IGF-I. Conversely, patients with basal GH<3.9 μg/l presented a variable biochemical pattern with half of them failing to suppress GH after OGTT and 36.6% displaying high IGF-I levels.

CONCLUSIONS

Our results show that baseline GH levels >3.9 μg/l are predictive of absent OGTT-dependent GH suppression; however, 20% of these patients display partial biochemical control (normal IGF-I levels). On the other hand, basal GH values <3.9 μg/l are not predictive of GH suppressibility by glucose and are often discordant with IGF-I levels.

Conventional and novel biomarkers of treatment outcome in patients with acromegaly: discordant results after somatostatin analog treatment compared with surgery

CONTEXT

Control of disease activity in acromegaly is critical, but the biochemical definitions remain controversial.

OBJECTIVE

To compare traditional and novel biomarkers and health status in patients with acromegaly treated with either surgery alone or somatostatin analog (SA).

DESIGN AND METHODS

Sixty-three patients in long-term remission based on normalized total IGF1 levels after surgery alone (n=36) or SA (n=27) were studied in a cross-sectional manner. The groups were comparable at diagnosis regarding demographic and biochemical variables. Each subject underwent 3 h of serum sampling including a 2-h oral glucose tolerance test (OGTT). Health status was measured by two questionnaires: EuroQoL and Acrostudy (Patient-assessed-Acromegaly symptom questionnaire (PASQ)).

RESULTS

Total and bioactive IGF1 (μg/l) levels were similar (total: 185 ± 10 (SA) versus 171 ± 8 (surgery) (P=0.28); bioactive: 1.9 ± 0.2 vs 1.9 ± 0.1 (P=0.70)). Suppression of total and free GH (μg/l) during OGTT was blunted in the SA group (total GH(nadir): 0.59 ± 0.08 (SA) versus 0.34 ± 0.06 (surgery) (P=0.01); free GH(nadir): 0.43 ± 0.06 vs 0.19 ± 0.04 (P<0.01)). The insulin response to OGTT was delayed, and the 2-h glucose level was elevated during SA treatment (P=0.02). Disease-specific health status was better in patients after surgery (P=0.02).

CONCLUSIONS

i) Despite similar and normalized IGF1 levels, SA treatment compared with surgery alone was associated with less suppressed GH levels and less symptom relief; ii) this discordance may be due to specific suppression of hepatic IGF1 production by SA; iii) we suggest that biochemical assessment during SA treatment should include both GH and IGF1.

The utility of oral glucose tolerance testing for diagnosis and assessment of treatment outcomes in 166 patients with acromegaly

CONTEXT

GH suppression after oral glucose load [oral glucose tolerance test (OGTT)] and normal age- and gender-matched IGF-I levels reflect biochemical control of acromegaly. The OGTT is the gold standard for determining control of GH secretion at diagnosis and after surgical treatment, but the usefulness of performing an OGTT in patients treated with medical therapy has not been determined.

OBJECTIVE

Our objective was to assess relationships between basal GH levels (basal GH), GH responses to OGTT [GH nadir (GHn)], and IGF-I levels.

DESIGN

This was a retrospective electronic database review.

SETTING

This study was performed at a tertiary outpatient pituitary center.

PATIENTS

A total of 166 patients with acromegaly (79 females, 87 males) were included in the study. Four categories of testing were performed: diagnosis, postoperative assessment without medication, testing during somatostatin analog (SA) therapy, and testing during dopamine agonist (DA) therapy.

MAIN OUTCOME MEASURES

Basal serum GH and IGF-I levels and GH levels 2 h after 75 g OGTT were measured.

RESULTS

A total of 482 simultaneous OGTT and IGF-I measurements were observed from 1985--2008. Discordant results of oral glucose tolerance testing (GHn and IGF-I) were observed 33, 48, and 18% in postoperative assessment without medication, SA, and DA categories, respectively. In the SA category, 42% of tests were discordant with normal IGF-I and nonsuppressed GHn. In contrast, 4% of tests were discordant with normal IGF-I and nonsuppressed GH in those treated with DA. No significant differences in discordance were observed when basal GH was used.

CONCLUSIONS

Both basal and GHn levels are highly discordant with IGF-I levels during medical therapy with SAs. The OGTT is not useful in assessing biochemical control in these subjects.

Prevalence of discordant GH and IGF-I levels in acromegalics at diagnosis, after surgical treatment and during treatment with octreotide LAR

BACKGROUND

Acromegalic patients are considered "discordant" if their insulin-like growth factor type I (IGF-I) levels are increased for their age with "safe" growth hormone (GH) levels or if their IGF-I levels are normal for their age with "unsafe" GH levels. The prevalence of discordance in acromegalics has been described to vary from 9.4% to 39%, and it may be observed at diagnosis or during the follow up.

OBJECTIVE

To evaluate the prevalence of discordant levels of IGF-I and GH in our acromegalic population.

METHODS

Hormonal evaluation was made with an oral glucose tolerance test (OGTT) with the IGF-I being assessed in the basal sample at diagnosis and after 3 months of the adenomectomy. During treatment with octreotide LAR, a GH curve (for the calculation of mean GH) and IGF-I assessment were made every 3 months.

RESULTS

Among the 51 patients evaluated at diagnosis, the prevalence of discordance was 13.7% (7/51). Among the 58 patients evaluated after the surgical procedure, eight (13.8%) had discordant GH and IGF-I levels. Among the 42 patients evaluated during treatment with octreotide LAR, the prevalence of discordant GH and IGF-I levels was 33.3% (14/42). Using 1 microg/L as a cut off level for "safe" GH, the prevalence of discordance was 3.9%, 8.6% and 28.6% at diagnosis, after surgery and during treatment with octreotide LAR, respectively. No difference of sex, age or treatment modality was observed among discordant and concordant patients with any GH cut off level.

CONCLUSION

We observed a prevalence of discordance similar to that previously described in the literature. We believe that studies evaluating morbidity and mortality in discordant patients are also necessary and will enlighten the true impact of this condition in the follow up of acromegaly.

Guidelines for the treatment of growth hormone excess and growth hormone deficiency in adults

The V Consensus Group Meeting on 'Guidelines for Treatment of GH Excess and GH Deficiency in the Adult' was an international workshop held on February 20-22, 2006 in Santa Monica, California, USA. The principal aim of this meeting was to provide guidelines for the evaluation and treatment of adults with either form of abnormal GH secretion: GH excess or GH deficiency. The workshop included debates as to the choice of primary treatment, discussions of the targets for adequate treatment, and concluded with presentations on open issues germane to adult GH treatment including the role of GH in malignancies, the impact of longterm treatment on bone, and a cost-benefit analysis. The meeting was comprised of 66 delegates representing 13 different countries.

An audit of treatment outcome in acromegalic patients attending our center at Bergamo, Italy

BACKGROUND

Acromegaly is a chronic disease impacting on morbidity and mortality. Increased mortality is reverted after the achievement of hormonal targets. The relative role of treatment options is still matter of debate.

METHODS

A retrospective chart review was performed on all the acromegalic patients attending our center along the last 20 years.

RESULTS

Data about 159 patients (83 F) were retrieved and analyzed: 18% had been lost to follow-up, while follow-up was >5 years in 79%. Growth hormone (GH) at diagnosis was 24 microg/L (median, range 3-239). Pituitary MRI showed a macro-, micro-adenoma or no lesion in 73.6, 22.9, and 3.5%, respectively. Hyperprolactinemia (hyperPRL) was present in 20.8%. Ninety-six and 29 patients had been treated by neurosurgery (NS) and irradiated (RT), respectively. Drugs had been employed in 149 patients (in 58 as the only treatment). At the last evaluation, 22% of patients were cured (hypopituitarism and GH deficiency in 6.3%), 37.1% were controlled by ongoing pharmacological treatment, 22.6% had discordant GH and Insulin-like growth factor I (IGF-I) values, and 18.2% had still active disease (median follow-up in this last group was 9 months). By evaluating the outcome with a multimodal approach, safe GH and normal IGF-I had been achieved in 78 and 63.5% of the whole series, 80.5 and 59.7% in patients submitted to NS (and adjuvantly treated with drugs), 95.8 and 91.7% in those submitted to NS + RT (and drugs as well), 70.2 and 55.2% in those treated only with drugs (increased to 82.2 and 60.9% if considering only patients treated with modern long-acting drugs). Hypopituitarism had occurred in 25, 66.6, and 13.8% in the three groups, respectively. At multivariate analysis, previous RT and NS were significant positive predictors of cure, whereas previous NS, follow-up, and year of diagnosis were significant positive predictors of control. Diabetes was a negative predictor both of cure and control. Sex, age, baseline GH levels, hyperPRL, tumor size, extrasellar extension, and invasiveness were not independent predictors of either cure or control.

CONCLUSION

This series seems to indicate that a multimodal approach can achieve control of disease in most patients.

Octreotide for acromegaly

Octreotide has dramatically changed the results of medical treatment of acromegaly. It is the reference drug for the pharmacological treatment of acromegaly, owing to its impressive efficacy in suppressing growth hormome secretion, and excellent compliance. Safe growth hormone and normal insulin-like growth factor I values are reached in 50-60% of unselected patients. Octreotide arrests the growth of the tumor and shrinks tumor in over half of all patients (namely, up to 88% of naive patients and to complete disappearance in anecdotic cases). The safety profile of octreotide is excellent, but in some patients, glucose metabolism worsens and cholelythiasis occurs. This review will address the primary treatment and the relative roles of pharmacological and surgical treatment, as well as the predictivity of octreotide results.