Long-term effects of pegvisomant in patients with acromegaly

How to improve effectiveness of pegvisomant treatment in acromegalic patients

PURPOSE

Pegvisomant (PEGV) treatment in acromegaly patients resistant to somatostatin analogues is less effective in the real life than in clinical trials. This is a multicenter, observational, retrospective, longitudinal study. The aim was to detect characteristics which improve long-term PEGV effectiveness.

METHODS

87 acromegalic patients treated with PEGV have been enrolled in seven referral Italian centres. PEGV was administered for up to 4 years, at doses up titrated until IGF-1 normalization or to ≥ 30 mg/day. The rate of patients who reached IGF-1 normalization at last visit has been calculated.

RESULTS

IGF-1 was normalized in 75.9% of patients after 1 year and in 89.6% at last visit. Disease control was associated with lower baseline GH, IGF-1 and IGF-1 xULN and was more frequent when baseline IGF-1 was < 2.7 × ULN (p < 0.02). PEGV dose was dependent on baseline IGF-1 > 2.7 × ULN (p < 0.05) and doses > 1.0 mg/BMI/day were administered more frequently when baseline IGF-1 was > 2.0 × ULN (p = 0.03). PEGV resistance was associated with higher BMI (p = 0.006) and was more frequent when BMI was > 30 kg/m² (p = 0.07). There were no significant differences between patients treated with monotherapy or combined treatment. IGF-1 normalization, PEGV dose and rate of associated treatment were similar between males and females. PEGV effectiveness was independent from previous management. Diabetic patients needed higher doses of PEGV than non-diabetic ones.

CONCLUSIONS

PEGV effectiveness improves when up titration is appropriate. Higher PEGV doses at start and a more rapid up-titration are necessary in patients with obesity and/or IGF-1 > 2.7 × ULN.

Effects of long-term combined treatment with somatostatin analogues and pegvisomant on cardiac structure and performance in acromegaly

To date, no data are available on the effects of long-term combined treatment with somatostatin analogues (SA) and pegvisomant (PEG) on cardiovascular complications in acromegaly. The current study aimed at investigating the effects of long-term SA + PEG on cardiac structure and performance. Thirty-six patients (14 M, 22 F, aged 52.3 ± 10.2 years) entered this study. Weight, BMI, systolic (SBP) and diastolic (DBP) blood pressure, IGF-I, fasting glucose (FG), fasting insulin (FI), HOMA-IR, HbA_1c, and lipids were evaluated at baseline (T0), after long-term (median 36 months) SA (T1), after 12 (T12) and 60 (T60) months of SA + PEG, and at last follow-up (LFU, median 78 months). At each time point, all patients underwent echocardiography. At T1, induced a slight but not significant decrease in IGF-I (p = 0.077), whereas FI (p = 0.004), HOMA-IR (p = 0.013), ejection fraction (EF, p = 0.013), early (E) to late (A) ventricular filling velocities (E/A, p = 0.001), and isovolumetric relaxation time (IVRT, p = 0.000) significantly improved. At T12, IGF-I (p = 0.000) significantly reduced compared to T0, and FI (p = 0.001), HOMA-IR (p = 0.000), LVMI (p = 0.000), and E/A (p = 0.006) further improved compared to T1. At T60, FI (p = 0.027), HOMA-IR (p = 0.049), and E/A (p = 0.005) significantly improved as compared to T1. At LFU IGF-I normalized in 83.3 %, FI (p = 0.000), HOMA-IR (p = 0.000), LVMi (p = 0.000), and E/A (p = 0.005) further improved as compared to T1. PEG dose significantly correlated with LVMi at T12 (r = 0.575, p = 0.000) and T60 (r = 0.403, p = 0.037). Long-term PEG addition to SA improves cardiac structure and performance, particularly diastolic dysfunction, in acromegalic patients resistant to SA.

Complications of acromegaly: cardiovascular, respiratory and metabolic comorbidities

Acromegaly is associated with an enhanced mortality, with cardiovascular and respiratory complications representing not only the most frequent comorbidities but also two of the main causes of deaths, whereas a minor role is played by metabolic complications, and particularly diabetes mellitus. The most prevalent cardiovascular complications of acromegaly include a cardiomyopathy, characterized by cardiac hypertrophy and diastolic and systolic dysfunction together with arterial hypertension, cardiac rhythm disorders and valve diseases, as well as vascular endothelial dysfunction. Biochemical control of acromegaly significantly improves cardiovascular disease, albeit completely recovering to normal mainly in young patients with short disease duration. Respiratory complications, represented mainly by sleep-breathing disorders, particularly sleep apnea, and respiratory insufficiency, frequently occur at the early stage of the disease and, although their severity decreases with disease control, this improvement does not often change the indication for a specific therapy directed to improve respiratory function. Metabolic complications, including glucose and lipid disorders, are variably reported in acromegaly. Treatments of acromegaly may influence glucose metabolism, and the presence of diabetes mellitus in acromegaly may affect the choice of treatments, so that glucose homeostasis is worth being monitored during the entire course of the disease. Early diagnosis and prompt treatment of acromegaly, aimed at obtaining a strict control of hormone excess, are the best strategy to limit the development or reverse the complications and prevent the premature mortality.

Genetic Predictors of Response to Different Medical Therapies in Acromegaly

In the era of predictive medicine, management of diseases is evolving into a more personal and individualized approach, as more data are available regarding clinical, biochemical, radiological, molecular, histopathological, and genetic aspects. In the particular setting of acromegaly, which is a rare, chronic, debilitating, and disfiguring disease, an optimized approach deems even more necessary, especially because of an associated increased morbidity and mortality, the impact on patients' quality of life, and the increased cost of frequently necessary life-long treatments. In this paper, we review the available studies that address potential genetic influences on acromegaly, their role in the outcome, and response to treatments, as well as their contribution to the risk of developing side effects. We focus mainly on pharmacogenetic factors involved during treatment with dopamine agonists, somatostatin analogs, and pegvisomant. Specifically, mutations in dopamine receptors, somatostatin receptors, growth hormone receptors, and metabolic pathways involved in growth hormone action; polymorphisms in the insulin-like growth factor and the insulin-like growth factor binding proteins; and polymorphisms in other genes that may determine differences in the frequency of developing adverse events.

Pegvisomant Treatment in Acromegaly

Historically, medical treatment of acromegaly has mainly been used as an adjuvant therapy after surgery. In the last decades, an increased range of medical therapy options has been available. Somatostatin analogues have become the cornerstones of medical treatment in acromegaly and are even seen as a primary treatment in a selected group of acromegaly patients. The most recent medical treatment available for acromegaly patients is pegvisomant, a growth hormone receptor antagonist. To date, it is the most effective medical treatment, but it is costly. Pegvisomant is used as monotherapy and combined with somatostatin analogues. In this article, we review clinical studies and cohorts that have documented the efficacy of pegvisomant monotherapy and combined therapy and give a concise overview of associated side effects.

Clinical importance of achieving biochemical control with medical therapy in adult patients with acromegaly

In acromegaly, achieving biochemical control (growth hormone [GH] level <1.0 ng/mL and age- and sex-normalized levels of insulin-like growth factor 1 [IGF-1]) through timely diagnosis and appropriate treatment provides an opportunity to improve patient outcomes. Diagnosis of acromegaly is challenging because it is rooted in observing subtle clinical manifestations, and it is typical for acromegaly to evolve for up to 10 years before it is recognized. This results in chronic exposure to elevated levels of GH and IGF-1 and delay in patients receiving appropriate treatment, which consequently increases mortality risk. In this review, the clinical impact of elevated GH and IGF-1 levels, the effectiveness of current therapies, and the potential role of novel treatments for acromegaly will be discussed. Clinical burden of acromegaly and benefits associated with management of GH and IGF-1 levels will be reviewed. Major treatment paradigms in acromegaly include surgery, medical therapy, and radiotherapy. With medical therapies, such as somatostatin analogs, dopamine agonists, and GH receptor antagonists, a substantial proportion of patients achieve reduced GH and normalized IGF-1 levels. In addition, signs and symptoms, quality of life, and comorbidities have also been reported to improve to varying degrees in patients who achieve biochemical control. Currently, there are several innovative therapies in development to improve patient outcomes, patient use, and access. Timely biochemical control of acromegaly ensures that the patient can ultimately improve morbidity and mortality from this disease and its extensive consequences.

Long-term results of fractionated stereotactic radiotherapy as third-line treatment in acromegaly

The treatment of acromegaly is based on surgery, drugs, and radiotherapy as a third-line option. Fractionated stereotactic radiotherapy (FSRT) is a new technique with a need for long-term evaluation. The purpose of the study was to evaluate long-term results of FSRT in acromegaly. Overall, 34 patients [sex ratio 1.12, age 45 (5-65) years] with a pituitary adenoma of 24.5 (9-76) mm including 20 invasive tumors were treated by radiotherapy in fractionated stereotactic conditions delivering 50 gy in 27 sessions. Baseline growth hormone (GH) and IGF1 levels were 18 (±14.5) and 632.6 (±339) µg/L, respectively. Indications of FSRT were failure of surgery and drug treatments (n = 30) or contraindication/refusal of surgery (n = 4). Hormonal control was defined by normal age- and sex-adjusted IGF1. Remission was defined by hormonal control after withdrawal of drugs for a minimum of three consecutive months. Data were analyzed in SPSS software with a significance level at p < 0.05. After a mean follow-up of 152 months, hormonal control was achieved in 33 patients (97 %) with withdrawal of drugs in 13 patients (38.2 %) without any recurrence. Factors found to be significantly associated to remission in a multivariate Cox regression were lower baseline hormone levels (GH and IGF1) and smaller tumor size. Tumor control was achieved in all patients. Acquired hypopituitarism after radiotherapy was the main side effect reported with a rate of 39 %. FSRT seems to be an effective and well tolerated third-line treatment of acromegaly, particularly adapted to macro adenomas treatment.

Need for improved monitoring in patients with acromegaly

Acromegaly is a rare and insidious disease characterized by the overproduction of growth hormone (GH) and insulin-like growth factor 1 (IGF1) and is most commonly due to a pituitary adenoma. Patients with acromegaly who experience prolonged exposure to elevated levels of GH and IGF1 have an increased mortality risk and progressive worsening of disease-related comorbidities. Multimodal treatment with surgery, medical therapy, and radiotherapy provides biochemical control, defined by recent acromegaly clinical guidelines from the Endocrine Society as a reduction of GH levels to <1.0 ng/ml and normalization of IGF1 levels, to a substantial proportion of patients and is associated with improved clinical outcomes. Patients with acromegaly, even those without clinical symptoms of disease, require long-term monitoring of GH and IGF1 levels if the benefits associated with biochemical control are to be maintained and the risk of developing recurrent disease is to be abated. However, suboptimal monitoring is common in patients with acromegaly, and this can have negative health effects due to delays in detection of recurrent disease and implementation of appropriate treatment. Because of the significant health consequences associated with prolonged exposure to elevated levels of GH and IGF1, optimal monitoring in patients with acromegaly is needed. This review article will discuss the biochemical assessments used for therapeutic monitoring in acromegaly, the importance of monitoring after surgery and medical therapy or radiotherapy, the consequences of suboptimal monitoring, and the need for improved monitoring algorithms for patients with acromegaly.

LIMITATIONS OF CURRENT APPROACHES FOR THE TREATMENT OF ACROMEGALY

OBJECTIVE

Acromegaly is a rare disease characterized by hypersecretion of growth hormone (GH), typically from a benign pituitary somatotroph adenoma, that leads to subsequent hypersecretion of insulin-like growth factor 1 (IGF-1). Patients with acromegaly have an increased risk of mortality and progressive worsening of comorbidities. Surgery, medical therapy, and radiotherapy are currently available treatment approaches for patients with acromegaly, with overall therapeutic goals of lowering GH levels and achieving normal IGF-1 levels, reducing tumor size, improving comorbidities, and minimizing mortality risk. Although surgery can lead to biochemical remission in some patients with acromegaly, many patients will continue to have uncontrolled disease and require additional treatment.

METHODS

We reviewed recently published reports and present a summary of the safety and efficacy of current treatment modalities for patients with acromegaly.

RESULTS

A substantial proportion of patients who receive medical therapy or radiotherapy will have persistently elevated GH and/or IGF-1. Because of the serious health consequences of continued elevation of GH and IGF-1, there is a need to improve therapeutic approaches to optimize biochemical control, particularly in high-need patient populations for whom current treatment options provide limited benefit.

CONCLUSION

This review discusses current treatment options for patients with acromegaly, limitations associated with each treatment approach, and areas within the current treatment algorithm, as well as patient populations for which improved therapeutic options are needed. Novel agents in development were also highlighted, which have the potential to improve management of patients with uncontrolled or persistent acromegaly.

Long-term efficacy and safety of pegvisomant in combination with long-acting somatostatin analogs in acromegaly

BACKGROUND

Treatment for acromegaly patients with long-acting somatotropin release-inhibiting factor (LA-SRIF) often does not result in complete normalization of IGF-1. Addition of pegvisomant (PEGV), a GH receptor antagonist, could improve this; however, the literature has not described long-term follow-up.

OBJECTIVE

To assess long-term efficacy and safety of this combined treatment in the largest current single-center cohort of patients, from 2004-2013.

DESIGN

Acromegaly patients were treated for at least 6 months with a high-dose LA-SRIF. To patients with persistently elevated IGF-1 levels (>1.2 × upper limit of normal) or poor quality of life, PEGV was added as one weekly injection.

RESULTS

The patients (n = 141) were treated with PEGV and LA-SRIFs for a median period of 4.9 years (range, 0.5-9.2). Efficacy, defined as the lowest measured IGF-1 level during treatment, was 97.0%. The median PEGV dose to achieve this efficacy was 80 mg weekly (interquartile range, 60-120 mg). Combination treatment-related adverse events were recorded in 26 subjects (18.4%). Pituitary tumor size increase was observed in one patient. Injection-site reactions were observed in four subjects. In 19 patients (13.5%), transiently elevated liver transaminases of more than three times the upper limit of normal were observed, of which 83% occurred within the first year of combination treatment. Eight patients died, at a mean age of 71 years; none of them were considered treatment-related.

CONCLUSIONS

The combination treatment with LA-SRIFs and PEGV was effective in 97% of the patients, it appears to be a safe medical treatment and it reduces the required dose of PEGV.

Role of UGT1A1 and ADH gene polymorphisms in pegvisomant-induced liver toxicity in acromegalic patients

CONTEXT

Hepatotoxicity is one of the most serious adverse effects in acromegalic patients treated with pegvisomant (PEG-V). Recent studies have found an association between this adverse event and the UGT1A1 allele 28 polymorphism associated with Gilbert's syndrome.

OBJECTIVE

To determine whether UGT1A1*28 and alcohol dehydrogenase (ADH) polymorphisms influence liver toxicity during PEG-V treatment.

DESIGN AND SETTING

Multicenter observational retrospective study conducted in 13 tertiary care endocrinology units in Italy.

PATIENTS

A total of 112 patients with active disease resistant to somatostatin analogs (SSTa) and 108 controls were enrolled.

INTERVENTIONS

Clinical and biochemical data were recorded by electronic clinical reporting forms. Blood or DNA samples were sent to the coordinating center for genotyping.

RESULTS

No differences in genotypes between patients and controls were found. During PEG-V therapy liver function tests (LFT), abnormalities and overt hepatotoxicity developed in 17 and 4.5% of patients respectively. Logistic and linear regression analyses showed an association between LFT abnormalities during the follow-up visit and prior events of LFT abnormalities in medical history (odds ratio=1.25; P=0.04) and the number of concomitant medications, other than SSTa (B=3.9; P=0.03). No correlation between LFT alterations and UGT1A1 allele 28 as well as ADH1C and B polymorphisms was found.

CONCLUSIONS

UGT1A1 allele 28 and ADH1C and B polymorphisms do not predict increased risk of hepatotoxicity during PEG-V therapy. Conversely, patients with multi-therapies and with previous episodes of liver disease should be carefully managed, due to the observed association between these conditions and LFT abnormalities during PEG-V therapy.

Pegvisomant and cabergoline combination therapy in acromegaly

Combination with cabergoline may offer additional benefits to acromegalic patients on pegvisomant monotherapy. We evaluated the safety and efficacy profile of this combination and investigated the determinants of response. An observational, retrospective, cross-sectional study. Fourteen acromegalic patients (9 females), who were partially resistant to somatostatin analogs and on pegvisomant monotherapy. Cabergoline was added because of the presence of persistent mildly increased IGF-I. The mean follow-up time was 18.3 ± 10.4 months. The efficacy and safety profile was assessed. The influence of clinical and biochemical characteristics on treatment efficacy was studied. IGF-I levels returned to normal in 4 patients (28%) at the end of the study. In addition, some decline in IGF-I levels was observed in a further 5 patients. The % IGF-I decreased from 158 ± 64% to 124 ± 44% (p = 0.001). The average change in IGF-I was -18 ± 27% (range -67 to +24%). Lower baseline IGF-I (p = 0.007), female gender (p = 0.013), lower body weight (p = 0.031), and higher prolactin (PRL) levels (p = 0.007) were associated with a better response to combination therapy. There were no significant severe adverse events. Significant tumour shrinkage was observed in 1 patient. Combination therapy with pegvisomant and cabergoline could provide better control of IGF-I in some patients with acromegaly. Baseline IGF-I levels, female gender, body weight, and PRL levels affect the response to this combination therapy.

Estrogen treatment for acromegaly

Estrogens have been used in patients with acromegaly since the 1930-1940s, suppressing plasma IGF-1 levels and improving clinical signs and symptoms of acromegaly. Estrogens antagonize GH function at the post-receptor level, inhibiting GH signaling, thus decreasing GH-induced hepatic IGF-1 synthesis. We report our experience with four female patients with active acromegaly, naïve to medical treatment or inadequately controlled by somatostatin receptor ligands (SRLs) or the GH-receptor antagonist. Adding estrogen treatment (contraceptive pills or transdermal estrogen patches) to their ongoing medical treatment, suppressed IGF-1 significantly in all patients, achieving hormonal remission in three of them. We review the available data on the use of estrogens and selective estrogen receptor modulators in acromegaly, and their mechanisms of action. Estrogens could be an alternative, inexpensive adjuvant treatment for females with active acromegaly, who are only partially responding to SRLs or to the GH-receptor antagonist.

Conversion of daily pegvisomant to weekly pegvisomant combined with long-acting somatostatin analogs, in controlled acromegaly patients

The efficacy of combined treatment in active acromegaly with both long-acting somatostatin analogs (SRIF) and pegvisomant (PEG-V) has been well established. The aim was to describe the PEG-V dose reductions after the conversion from daily PEG-V to combination treatment. To clarify the individual beneficial and adverse effects, in two acromegaly patients, who only normalized their insulin like growth factor (IGF-I) levels with high-dose pegvisomant therapy. We present two cases of a 31 and 44 years old male with gigantism and acromegaly that were controlled subsequently by surgery, radiotherapy, SRIF analogs and daily PEG-V treatment. They were converted to combined treatment of monthly SSA and (twice) weekly PEG-V. High dose SSA treatment was added while the PEG-V dose was decreased during carful monitoring of the IGF-I. After switching from PEG-V monotherapy to SRIF analogs plus pegvisomant combination therapy IGF-I remained normal. However, the necessary PEG-V dose, to normalize IGF-I differed significantly between these two patients. One patient needed twice weekly 100 mg, the second needed 60 mg once weekly on top of their monthly lanreotide Autosolution injections of 120 mg. The weekly dose reduction was 80 and 150 mg. After the introducing of lanreotide, fasting glucose and glycosylated haemoglobin concentrations increased. Diabetic medication had to be introduced or increased. No changes in liver tests or in pituitary adenoma size were observed. In these two patients, PEG-V in combination with long-acting SRIF analogs was as effective as PEG-V monotherapy in normalizing IGF-I levels, although significant dose-reductions in PEG-V could be achieved. However, there seems to be a wide variation in the reduction of PEG-V dose, which can be obtained after conversion to combined treatment.

Cotreatment with pegvisomant and a somatostatin analog (SA) in SA-responsive acromegalic patients

CONTEXT

Cotreatment of acromegaly with pegvisomant and a somatostatin analog (SA) has proven feasible. Previous studies in the field have focused on patients with an insufficient response to SA monotherapy in whom pegvisomant was added without changing the SA dose.

OBJECTIVE

The objective of the study was to study whether patients sufficiently controlled on SA monotherapy can be transferred to combination therapy with low-dose pegvisomant and a reduced SA dose.

DESIGN

Eighteen acromegalic patients well controlled on SA monotherapy, mean ± se aged 54 ± 3 yr, were randomized in a parallel study over 24 wk to unchanged SA monotherapy or cotreatment with pegvisomant (15-30 mg twice a week) and SA (half the usual dosage).

SETTING

This was an investigator-initiated study in a single tertiary referral center.

MAIN OUTCOME MEASURES

Glucose tolerance, substrate metabolism, insulin sensitivity, body composition, and quality of life were measured.

RESULTS

Median pegvisomant dose was 52.5 mg/wk (range 30-60). IGF-I (micrograms per liter) was comparable both at baseline (P = 0.88) and after 24 wk of treatment (P = 0.48). The change in IGF-I between baseline and wk 24 also did not differ between groups (P = 0.15). Apart from increased peak insulin levels during the oral glucose tolerance test in the cotreatment group, no substantial differences between the two groups were detected. Moderately elevated liver enzymes were found in 17% of the patients on pegvisomant therapy.

CONCLUSION

Acromegalic patients well controlled on SA monotherapy can maintain safe IGF-I levels during 24 wk of cotreatment with low-dose pegvisomant and a 50% reduced SA dose. This treatment modality, however, does not seem to provide significant benefits for the patients.

Medical therapy of acromegaly in Turkey

Acromegaly is associated with multiple co-morbidities and risk of premature mortality. Mortality rate of acromegalic patients is similar to that of the general population when normal GH levels are achieved. Surgery is the mainstay of acromegaly but when surgery fails to achieve disease control, or when surgery is impossible or contraindicated, patients are offered medical therapy and/or radiotherapy. Current medical therapy modalities were revised in this short review.

[Treatment of acromegaly]

Growth hormone (GH) hypersecretion leads to acromegaly which is associated with several co-morbidities and increased mortality. Despite of the typical clinical features and modern diagnostic tools, it often takes years from the onset of the disease until the diagnosis. The aims of the treatment are to reduce or control the tumor growth, inhibit the GH hypersecretion, normalize the insulin-like growth factor-I (IGF-I) levels, treat the co-morbidities and therefore reduce mortality. There are three approaches for therapy: surgery, medical management (dopamine agonist, somatostatin analogues and GH receptor antagonist), and radiotherapy. Efficient therapy of the disease is based on the appropriate multidisciplinary team management.

Immunogenicity, toxicology, pharmacokinetics and pharmacodynamics of growth hormone ligand-receptor fusions

A fundamental concern for all new biological therapeutics is the possibility of inducing an immune response. We have recently demonstrated that an LR-fusion (ligand-receptor fusion) of growth hormone generates a potent long-acting agonist; however, the immunogenicity and toxicity of these molecules have not been tested. To address these issues, we have designed molecules with low potential as immunogens and undertaken immunogenicity and toxicology studies in Macaca fascicularis and pharmacokinetic and pharmacodynamic studies in rats. Two variants of the LR-fusion, one with a flexible linker (GH-LRv2) and the other without (GH-LRv3), were tested. Comparison was made with native human GH (growth hormone). GH-LRv2 and GH-LRv3 demonstrated similar pharmacokinetics in rats, showing reduced clearance compared with native GH and potent agonist activity with respect to body weight gain in a hypophysectomized rat model. In M. fascicularis, a low level of antibodies to GH-LRv2 was found in one sample, but there was no other evidence of any immunogenic response to the other fusion protein. There were no toxic effects and specifically no changes in histology at injection sites after two repeated administrations. The pharmacokinetic profiles in monkeys confirmed long half-lives for both GH-LRv2 and GH-LRv3 representing exceptionally delayed clearance over rhGH (recombinant human GH). The results suggest that repeated administration of a GH LR-fusion is safe, non-toxic, and the pharmacokinetic profile suggests that two to three weekly administrations is a potential therapeutic regimen for humans.

Pegvisomant-induced liver injury is related to the UGT1A1*28 polymorphism of Gilbert's syndrome

CONTEXT

Pegvisomant (PEG) therapy has been associated with drug-induced liver dysfunction in acromegalic patients. The mechanism of its toxicity remains unknown.

OBJECTIVE

The primary objective was to determine whether or not the UGT1A1*28 polymorphism associated with Gilbert's syndrome influences the development of liver dysfunction during PEG treatment.

DESIGN AND SETTING

A cross-sectional study was conducted in four Spanish university hospitals.

PATIENTS

Thirty-six acromegalic patients with active disease, resistant to somatostatin analogs, participated.

RESULTS

The prevalence of the UGT1A1*28 homozygous and heterozygous genotypes in acromegalic patients was 14 and 44%, respectively. Ten patients (28%) developed liver function test (LFT) abnormalities. There was a tendency for more frequent liver function abnormalities in males (70% males vs. 30% females, P = 0.058). Carriers of the UGT1A1*28 polymorphism had a higher incidence of LFT abnormalities than the UGT1A1 wild type (43% carriers vs. 7% wild type, P = 0.024). This difference persisted when adjusted in an all-factors multiple regression analysis [coefficient of determination (R(2)) = 0.463; P = 0.008] for age, gender, alcohol consumption, and UGT1A1*28 polymorphism. A stepwise multivariate likelihood binary logistic regression analysis (R(2) = 0.40; P = 0.003) identified male gender (beta = 7.21; P = 0.033) and UGT1A1*28 polymorphism (beta = 14.1; P = 0.028) as the only significant predictors for the development of LFT abnormalities.

CONCLUSIONS

The UGT1A1*28 genotype and male gender predict an increased incidence of LFT abnormalities during PEG therapy in acromegaly.

Fractionated stereotactic radiotherapy in patients with acromegaly: an interim single-centre audit

AIM

To evaluate the effect of fractionated stereotactic radiotherapy (FSRT) in acromegaly in a retrospective analysis.

PATIENTS AND METHODS

Thirty-four patients (17 females, median 43 years (range 30-74)) with acromegaly were treated with FSRT (conformal dynamic arcing, dose 54 Gy, 27-30 fractions) between January 1998 and April 2007. Of the 34 patients, 32 had undergone transsphenoidal adenotomy, and 28 were on medical therapy before FSRT. Patients on medical therapy continued this during and after the irradiation. The treatment was gradually decreased/withdrawn after careful assessment.

RESULTS

Magnetic resonance scanning of the pituitary gland 34 months (median, range 11-95) after irradiation showed stable or reduced volume of the remaining tumour tissue in 31 of 34 patients (91%). Seventeen patients (50%) were biochemically controlled (normalised nadir GH during oral glucose tolerance test and IGF1 <+2 S.D.) 30 months after FSRT (median, range 6-60), and ten of them had true biochemical remission (off medical therapy) 30 months after FSRT (median, range 12-69). Of 28 patients with one or more functioning pituitary axes before irradiation, 8 (29%) developed further deficit of one or two pituitary axes 48 months (median, range 6-102) after FSRT. Of 34 patients, 20 still required medical treatment for acromegaly at the end of this study, mainly those with a short follow-up period after irradiation.

CONCLUSION

The FSRT seems promising in terms of treatment of acromegaly. Longer follow-up is, however, needed to assess the overall efficacy and safety of FSRT for acromegaly.

Tumor volume of growth hormone-secreting pituitary adenomas during treatment with pegvisomant: a prospective multicenter study

CONTEXT

Clinical and biochemical remission in acromegaly can frequently be achieved with the recombinant GH receptor antagonist pegvisomant, even when other treatments fail. However, increases in tumor volume have been reported.

OBJECTIVE

Because previous studies suffer from inhomogenous magnetic resonance imaging (MRI) protocols, this prospective study examined the long-term course of adenoma volume during pegvisomant therapy by standardized MRI.

DESIGN

Five centers in Germany participated. High-resolution MRI was performed at baseline and 6, 12, and 24 months after enrollment.

SETTING/PATIENTS

Patients were outpatients, and pegvisomant is third-line therapy in most of the cases.

MAIN OUTCOME MEASURES

The primary end point was tumor volume at 24 month follow-up, measured by a single, double-blinded rater.

RESULTS

Forty-five of 61 patients completed 24 months' follow-up (73.8%). Tumor volume increase greater than 25% during the study was observed in three of 61 patients (4.9%), all during the first year of enrollment. All three patients had had octreotide treatment before initiation of pegvisomant; none of them had had radiotherapy. All volumetric findings were comparable with clinical radiological interpretations. ANOVA revealed no significant change in tumor volume after 24 months (n = 45).

CONCLUSIONS

This study shows that pegvisomant therapy infrequently coincides with tumor growth during long-term treatment of acromegaly. Because all significant tumor volume increases occurred during the first year, these changes might correlate to the change of medication and thus be the result of a rebound from somatostatin-induced shrinkage.

Somatostatin analog and pegvisomant combination therapy for acromegaly

Optimal biochemical control cannot be attained by long-acting somatostatin analog monotherapy in a large proportion of patients with acromegaly. Such therapy might result in increased mortality, poor control of signs and symptoms of disease and decreased quality of life. Combination treatment with somatostatin analogs and pegvisomant (a growth-hormone-receptor antagonist) is, however, highly effective at normalizing the level of insulin-like growth factor I in over 90% of patients and might also have a favorable effect on quality of life in those with biochemically controlled acromegaly. Moreover, whereas pegvisomant monotherapy does not lead to a decrease in the size of the pituitary tumor, combination therapy with somatostatin analogs results in a clinically relevant decrease in tumor size in about 20% of patients. The main adverse effects of combination treatment are transient elevations in the levels of transaminases, which occur in about 15% of patients, especially in those with diabetes mellitus. In this Review, we discuss the available data on the long-term efficacy and safety of somatostatin analog-pegvisomant combination treatment and its potential use in patients with acromegaly.

Pegvisomant-induced cholestatic hepatitis with jaundice in a patient with Gilbert's syndrome

We report on a patient with active acromegaly and Gilbert's syndrome who developed severe hepatic dysfunction during pegvisomant (PEGv) monotherapy. She was partially resistant to all previous therapies, including long-acting somatostatin analogs and cabergoline. Five months after starting PEGv therapy, with an already normalized IGF1, she developed cholestatic liver dysfunction with jaundice. Liver or biliary diseases including biliary sludge, cholelithiasis or liver steatosis were excluded. A liver biopsy was in keeping with drug-induced liver injury. The discontinuation of PEGv was followed by full clinical and biochemical recovery in 6 weeks. PEGv therapy was not resumed. Apart from a minimal increase of bilirubin levels, no liver function test abnormalities were found during the 4-year follow-up period after the PEGv was discontinued. Drug-induced liver injury is the most serious systemic adverse event resulting from PEGv therapy. Since patients with mild and asymptomatic liver disease could be at a higher risk of PEGv-induced hepatotoxicity, frequent monitoring of hepatic enzymes should be required in these cases.