Gender, body weight, disease activity, and previous radiotherapy influence the response to pegvisomant

Biomarkers of response to treatment in acromegaly

INTRODUCTION

Medical treatment of acromegaly is based in a `trial and error` approach. First-generation somatostatin receptor ligands (fg-SRL) are prescribed as first-line medical therapy to the vast majority of patients, despite lack of disease control in approximately 60% of patients. However, other drugs used in acromegaly treatment are available (cabergoline, pasireotide and pegvisomant).

AREAS COVERED

In this article, we review and discuss the biomarkers of response to medical treatment in acromegaly.

EXPERT OPINION

Biomarkers for fg-SRL that can already be applied in clinical practice are: gender, age, pretreatment GH and IGF-I levels, cytokeratin granulation pattern, and the expression of somatostatin receptor type 2. Using biomarkers of response could guide treatment towards precision medicine with greater efficacy and lower costs.

Second line treatment of acromegaly: Pasireotide or Pegvisomant?

Acromegaly is a chronic disease with an increased mortality in case of persistently active disease. The treatment of acromegaly is mainly based on the surgical resection of the GH secreting pituitary tumor and, in cases with persistent disease, on the medical therapy with first generation somatostatin analogues (first gen-SSAs). Data from national registries, meta-analysis and epidemiology studies showed that 24%-65% of acromegaly patients treated with first gen-SSA did not reach the control of disease, requiring second line therapies, as the second gen-SSAs and the GH receptor antagonist. According to the high efficacy of these treatments and their molecular mechanisms of action, the choice of second line therapies should be personalized. In this review, we summarize the evidence on clinical, molecular and morphological aspects that may predict the response to second line therapies, in order to integrate and translate in the clinical practice for a patient-tailored therapeutic approach.

Acromegaly: pathogenesis, diagnosis, and management

Growth hormone-secreting pituitary adenomas that cause acromegaly arise as monoclonal expansions of differentiated somatotroph cells and are usually sporadic. They are almost invariably benign, yet they can be locally invasive and show progressive growth despite treatment. Persistent excess of both growth hormone and its target hormone insulin-like growth factor 1 (IGF-1) results in a wide array of cardiovascular, respiratory, metabolic, musculoskeletal, neurological, and neoplastic comorbidities that might not be reversible with disease control. Normalisation of IGF-1 and growth hormone are the primary therapeutic aims; additional treatment goals include tumour shrinkage, relieving symptoms, managing complications, reducing excess morbidity, and improving quality of life. A multimodal approach with surgery, medical therapy, and (more rarely) radiation therapy is required to achieve these goals. In this Review, we examine the epidemiology, pathogenesis, diagnosis, complications, and treatment of acromegaly, with an emphasis on the importance of tailoring management strategies to each patient to optimise outcomes.

Are there country-specific differences in the use of pegvisomant for acromegaly in clinical practice? An analysis from ACROSTUDY

OBJECTIVE

A comprehensive picture of pegvisomant use for treating acromegaly in routine clinical practice in different countries is lacking. We aimed, therefore, to document country-specific behaviors in real-life pegvisomant use, and the main safety and effectiveness outcomes in the ACROSTUDY.

DESIGN

ACROSTUDY is an open-label, non-interventional, post-marketing safety surveillance study.

METHODS

A descriptive analysis was performed using data from the six top-recruiter ACROSTUDY countries, i.e., Germany (n = 548 patients), Italy (n = 466), France (n = 312), USA (n = 207), Spain (n = 200) and the Netherlands (n = 175). These nations accounted for > 85% of the ACROSTUDY cases.

RESULTS

The mean pegvisomant dose at treatment start was lowest in the Netherlands (9.4 mg/day), whereas it ranged between 10.9 and 12.6 mg/day in the other countries. At year 5, the mean pegvisomant dose was around 15 mg/day in all countries, except France (18.1 mg/day). At starting pegvisomant, patients treated with monotherapy ranged between 15% in the Netherlands and 72% in Spain. Monotherapy remained lowest over time in the Netherlands. In all countries, the percentage of patients with normal IGF-1 increased steeply from < 20% at baseline to 43-58% at month 6 and 51-67% at year 1. After that, we observed minor changes in the rate of acromegaly control in all countries. The Netherlands peaked in disease control at year 2 (72%). The proportion of patients reporting changes in pituitary tumor size was generally low. Serious treatment-related adverse events were < 5% in all countries.

CONCLUSIONS

Our study provided a detailed summary of real-life use of pegvisomant in the six top-recruiter ACROSTUDY nations.

Pegvisomant treatment in acromegaly in clinical practice: Final results of the French ACROSTUDY (312 patients)

OBJECTIVE

We report the final analysis of the French ACROSTUDY, using data revised and enriched since the 2013 interim analysis. Our objective was to validate the use of pegvisomant (PEGV) in the treatment of acromegaly and to determine efficacy and safety.

PATIENTS AND METHODS

Patients with acromegaly treated with PEGV and followed up for at least 5 years were included. Eighty-eight investigators from 62 clinical centers in France included patients from April 2007 to April 2014. PEGV dose and administration frequency were determined by the physicians, based on their clinical evaluation and local habits. No additional examinations beyond those performed in normal follow-up were required. Minimum recommended follow-up included check-ups at treatment initiation, 6 months, 12 months and then annually.

RESULTS

In total, 312 patients were enrolled. Mean age was 46.1±14.3 years at introduction of PEGV. Median PEGV treatment duration was 6.3 years and median follow-up was 5.6 years. Median dose at initiation was 10mg/day. The percentages of patients with IGF-1 ≤ ULN (upper limit of normal) were 10% (n=300) at baseline, 54% at 6 months (n=278), and 61.7% (n=253) at 2 years, then stabilizing at 64.4% (n=180) at 5 years. Mean PEGV dose was 17.4±11.7mg in patients with controlled disease versus 21.1±17.3mg in those without control at 5 years. At 5 years, 21.8% of patients (54/248) were receiving >30mg PEGV per day. In patients with at least one pituitary imaging procedure during the 5-year follow-up (n=292), the most recent image showed stable tumor volume in 212 subjects (72.6%), increased volume in 13 (4.5%), and decreased volume in 30 (10.3%). No PEGV treatments were permanently discontinued due to transaminase elevation. There were no cases of liver failure.

CONCLUSION

The French ACROSTUDY showed normalization of IGF-1 levels in 64.4% of a real-life cohort of patients, mostly with uncontrolled disease despite multiple prior therapies. Long-term follow-up showed a sustained effectiveness and good long-term safety.

Acromegaly in the elderly patients

BACKGROUND

Acromegaly is a rare disease characterized by a chronic exposition to growth hormone (GH) and insulin-like growth factor-1 (IGF-1), caused in most cases by a pituitary GH-secreting adenoma. Chronic GH excess induces systemic complications (metabolic, cardiovascular, respiratory, neoplastic, and musculoskeletal) and increased mortality if not appropriately treated. Recent epidemiological data report an improved life span of patients with acromegaly probably due to better acromegaly management; additionally, the number of pituitary incidentaloma in general population also increased over time due to more frequent imaging. Therefore, the number of elderly patients, newly diagnosed with acromegaly or in follow-up, is expected to grow in the coming years and clinicians will need to be aware of particularities in managing these patients.

PURPOSE

This review aims to explore different aspects of acromegaly of the elderly patients, focusing on epidemiology, diagnosis, clinical presentation, complications, and management options.

METHODS

Available literature has been assessed through PubMed (data until August 2019) by specific keywords.

CONCLUSIONS

Available data on acromegaly in the elderly patient are sparse, but point to important differences. Further studies are needed comparing elderly with younger patients with acromegaly to better define a tailored diagnostic and therapeutic management.

Brazilian multicenter study on pegvisomant treatment in acromegaly

OBJECTIVE

Investigate the therapeutic response of acromegaly patients to pegvisomant (PEGV) in a real-life, Brazilian multicenter study.

SUBJECTS AND METHODS

Characteristics of acromegaly patients treated with PEGV were reviewed at diagnosis, just before and during treatment. All patients with at least two IGF-I measurements on PEGV were included. Efficacy was defined as any normal IGF-I measurement during treatment. Safety data were reviewed. Predictors of response were determined by comparing controlled versus uncontrolled patients.

RESULTS

109 patients [61 women; median age at diagnosis 34 years; 95.3% macroadenomas] from 10 Brazilian centers were studied. Previous treatment included surgery (89%), radiotherapy (34%), somatostatin receptor ligands (99%), and cabergoline (67%). Before PEGV, median levels of GH, IGF-I and IGF-I % of upper limit of normal were 4.3 µg/L, 613 ng/mL, and 209%, respectively. Pre-diabetes/diabetes was present in 48.6% and tumor remnant in 71% of patients. Initial dose was 10 mg/day in all except 4 cases, maximum dose was 30 mg/day, and median exposure time was 30.5 months. PEGV was used as monotherapy in 11% of cases. Normal IGF-I levels was obtained in 74.1% of patients. Glycemic control improved in 56.6% of patients with pre-diabetes/diabetes. Exposure time, pre-treatment GH and IGF-I levels were predictors of response. Tumor enlargement occurred in 6.5% and elevation of liver enzymes in 9.2%. PEGV was discontinued in 6 patients and 3 deaths unrelated to the drug were reported.

CONCLUSIONS

In a real-life scenario, PEGV is a highly effective and safe treatment for acromegaly patients not controlled with other therapies.

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.

MANAGEMENT OF ENDOCRINE DISEASE: Personalized medicine in the treatment of acromegaly

Acromegaly is associated with high morbidity and elevated mortality when not adequately treated. Surgery is the first-line treatment for most patients as it is the only one that can lead to immediate cure. In patients who are not cured by surgery, treatment is currently based on a trial-and-error approach. First-generation somatostatin receptor ligands (fg-SRL) are initiated for most patients, although approximately 25% of patients present resistance to this drug class. Some biomarkers of treatment outcome are described in the literature, with the aim of categorizing patients into different groups to individualize their treatments using a personalized approach. In this review, we will discuss the current status of precision medicine for the treatment of acromegaly and future perspectives on the use of personalized medicine for this purpose.

Pegvisomant in acromegaly: an update

BACKGROUND

In 2007, we published an opinion document to review the role of pegvisomant (PEG) in the treatment of acromegaly. Since then, new evidence emerged on the biochemical and clinical effects of PEG and on its long-term efficacy and safety.

AIM

We here reviewed the emerging aspects of the use of PEG in clinical practice in the light of the most recent literature.

RESULTS

The clinical use of PEG is still suboptimal, considering that it remains the most powerful tool to control IGF-I in acromegaly allowing to obtain, with a pharmacological treatment, the most important clinical effects in terms of signs and symptoms, quality of life and comorbidities. The number of patients with acromegaly exposed to PEG worldwide has become quite elevated and the prolonged follow-up allows now to deal quite satisfactorily with many clinical issues including major safety issues, such as the concerns about possible tumour (re)growth under PEG. The positive or neutral impact of PEG on glucose metabolism has been highlighted, and the clinical experience, although limited, with sleep apnoea and pregnancy has been reviewed. Finally, the current concept of somatostatin receptor ligands (SRL) resistance has been addressed, in order to better define the acromegaly patients to whom the PEG option may be offered.

CONCLUSIONS

PEG increasingly appears to be an effective and safe medical option for many patients not controlled by SRL but its use still needs to be optimized.

A multivariable prediction model for pegvisomant dosing: monotherapy and in combination with long-acting somatostatin analogues

BACKGROUND

Effective treatment of acromegaly with pegvisomant (PEGV), a growth hormone receptor antagonist, requires an appropriate dose titration. PEGV doses vary widely among individual patients, and various covariates may affect its dosing and pharmacokinetics.

OBJECTIVE

To identify predictors of the PEGV dose required to normalize insulin-like growth factor I (IGF-I) levels during PEGV monotherapy and in combination with long-acting somatostatin analogues (LA-SSAs).

DESIGN

Two retrospective cohorts (Rotterdam + Liège Acromegaly Survey (LAS), total n = 188) were meta-analyzed as a form of external replication to study the predictors of PEGV dosing in addition to LA-SSA, the LAS (n = 83) was used to study the predictors of PEGV monotherapy dosing. Multivariable regression models were used to identify predictors of the PEGV dose required to normalize IGF-I levels.

RESULTS

For PEGV dosing in combination with LA-SSA, IGF-I levels, weight, height and age, were associated with the PEGV normalization dosage (P ≤ 0.001, P ≤ 0.001, P = 0.028 and P = 0.047 respectively). Taken together, these characteristics predicted the PEGV normalization dose correctly in 63.3% of all patients within a range of ±60 mg/week (21.3% within a range of ±20 mg/week). For monotherapy, only weight was associated with the PEGV normalization dose (P ≤ 0.001) and predicted this dosage correctly in 77.1% of all patients within a range of ±60 mg/week (31.3% within a range of ±20 mg/week).

CONCLUSION

In this study, we show that IGF-I levels, weight, height and age can contribute to define the optimal PEGV dose to normalize IGF-I levels in addition to LA-SSA. For PEGV monotherapy, only the patient's weight was associated with the IGF-I normalization PEGV dosage.

Effectiveness of first-line pegvisomant monotherapy in acromegaly: an ACROSTUDY analysis

OBJECTIVE

To examine the effectiveness and safety of primary pegvisomant monotherapy.

DESIGN

Retrospective analysis of data extracted from ACROSTUDY (global observational outcomes study of patients with acromegaly treated with pegvisomant).

METHODS

The earliest time to insulin-like growth factor 1 (IGF-1) normalization on pegvisomant monotherapy was determined. Both the proportion of patients who achieved IGF-1 normalization and the time to IGF-1 normalization on pegvisomant monotherapy were assessed.

RESULTS

Eligible patients included 28 subjects on primary medical therapy (PT) and 176 controls on adjunctive pegvisomant therapy treated postoperatively, including 43 who were naïve to medical therapy (NMT) and 133 who were previously treated medically and were washed out (WASH). IGF-1 normalization occurred in 76.9% (PT), 85.2% (NMT) and 78.3% (WASH) patients (P = NS). Median times to IGF-1 normalization were 0.5 year (PT), 0.7 year (NMT) and 0.6 year (WASH), P = NS. On survival analysis, the fraction of patients controlled on pegvisomant monotherapy was not different between groups. Higher baseline IGF-1 levels, obtained at study entry, predicted a lower likelihood of IGF-1 normalization on monotherapy (P = 0.012). Safety data include low prevalence of skin rashes, injection site reactions and reversible transaminase elevations. There was one patient (NMT) with a verified increase in tumor size.

CONCLUSIONS

Pegvisomant monotherapy, administered either as primary medical therapy or as adjunctive therapy according to local practice, led to IGF-1 normalization in >75% of patients. Pegvisomant monotherapy had a favorable safety profile, consistent with previous observations. Prospective data are needed to further evaluate the role of primary pegvisomant monotherapy in acromegaly.

Pegvisomant: a growth hormone receptor antagonist used in the treatment of acromegaly

PURPOSE

To review published data on pegvisomant and its therapeutic role in acromegaly.

METHODS

Electronic searches of the published literature were conducted using the keywords: acromegaly, growth hormone (GH) receptor (antagonist), pegvisomant, therapy. Relevant articles (n = 141) were retrieved and considered for inclusion in this manuscript.

RESULTS

Pegvisomant is a genetically engineered, recombinant growth hormone receptor antagonist, which is effective in normalizing serum insulin-like growth factor 1 (IGF-1) levels in the majority of patients with acromegaly and ameliorating symptoms and signs associated with GH excess. Pegvisomant does not have direct antiproliferative effects on the underlying somatotroph pituitary adenoma, which is the etiology of GH excess in the vast majority of patients with acromegaly. Therefore, patients receiving pegvisomant monotherapy require regular pituitary imaging in order to monitor for possible increase in tumor size. Adverse events in patients on pegvisomant therapy include skin rashes, lipohypertrophy at injection sites, and idiosyncratic liver toxicity (generally asymptomatic transaminitis that is reversible upon drug discontinuation), thus necessitating regular patient monitoring.

CONCLUSIONS

Pegvisomant is an effective therapeutic agent in patients with acromegaly who are not in remission after undergoing pituitary surgery. It mitigates excess GH action, as demonstrated by IGF-1 normalization, but has no direct effects on pituitary tumors causing acromegaly. Regular surveillance for possible tumor growth and adverse effects (hepatotoxicity, skin manifestations) is warranted.

Experience with pegvisomant treatment in acromegaly in a single Brazilian tertiary reference center: efficacy, safety and predictors of response

Objective

To describe the safety and efficacy of pegvisomant therapy and the predictors of treatment response in acromegaly patients at a single tertiary reference center in Brazil.

Materials and methods

We retrospectively reviewed the clinical, hormonal and radiological data of acromegaly patients treated with pegvisomant in our center. We also evaluated the presence of the d3 isoform of the growth hormone receptor (d3GHR).

Results

Twenty-seven patients were included (17 women). Pegvisomant was used in combination with octreotide LAR in 20 patients (74%), in combination with cabergoline in one (4%) and as monotherapy in six (22%). IGF-I normalization was achieved in 23 patients (85%). Mild and transitory elevation of liver enzymes was observed in two patients (7.4%), tumor growth in one (3.4%) and lipodystrophy in two (7.4%). One patient stopped the drug due to headaches. The GHR isoforms were evaluated in 14 patients, and the presence of at least one d3GHR allele was observed in 43% of them, but it was not a predictor of treatment response. Only pre-treatment IGF-I level was a predictor of treatment response.

Conclusion

Pegvisomant treatment was highly effective and safe in our series of Brazilian patients. A better chance of disease control can be expected in those with lower pre-pegvisomant IGF-I levels.

Treatment with high doses of pegvisomant in 56 patients with acromegaly: experience from ACROSTUDY

OBJECTIVE

To investigate the characteristics of patients who need more or less pegvisomant (PEGV) to normalize serum IGF-I.

DESIGN

ACROSTUDY is a global noninterventional safety surveillance study of long-term treatment outcomes in patients treated with PEGV. As of June, 2014, ACROSTUDY included data on 2016 patients. All patients treated for at least 6weeks at a dose above 30mg/day and who had two consecutive normal serum IGF-I values were included in the 'high'-dose group (H; n=56; mean daily dose 44±12.5; median dose 40, 35-60 (10-90%)). Patients with two consecutive normal IGF-I values and who never received a PEGV dose above 10mg/day were included in the 'low'-dose group (L; n=368; mean daily dose 7.5±2.5; median dose 8.6, 4.3-10 (10-90%)).

RESULTS

Patients in the H group were significantly younger (median 47 vs 52years) and had a significantly higher BMI (median 31.8 vs 26.5kg/m(2)). They had more diabetes (55% vs 21%), sleep apnea (25% vs 14 %) and more hypertension (61% vs 43%). The incidence of (serious) adverse events was low and was not different between the groups.

CONCLUSIONS

Patients who need more PEGV to normalize IGF-I have more aggressive disease, as they are younger, have higher baseline IGF-I levels, more hypertension, more sleep apnea and diabetes and are more overweight. A better understanding of this dose-efficacy relationship of PEGV might avoid inappropriate dosing and prevent serum IGF-I levels from remaining unnecessarily uncontrolled.

Safety of long-term treatment with Pegvisomant: analysis of Spanish patients included in global ACROSTUDY

PURPOSE

To evaluate the long-term safety of Pegvisomant (PEG) in the Spanish cohort of ACROSTUDY.

METHODS

As of July 2013, 199 Spanish patients were included in ACROSTUDY, a global non interventional safety PEG surveillance study. Patients were observed for safety, biochemical outcome and magnetic resonance imaging evaluations.

RESULTS

PEG was administered during an average period of 6.7 ± 2.1 years and a mean daily dose of 15.5 ± 7.5 mg. 48.2% of patients received PEG monotherapy. 90.9% of patients had received other medical treatment before PEG start. 195 adverse events (AEs) were reported in 88 patients (44.2%), and serious AEs were described in 31 patients (15.6%). There were no cases of liver tests >10 ULN, or permanent liver damage. Tumor size changes were locally reported in 61 cases (33.5%), with increases observed in 11 patients (6%). In acromegalic patients with diabetes mellitus a decrease in fasting serum glucose value was reported, reaching statistical significance after 1 and 4 years of treatment (-24.6 and -25.9 mg/dl, p = 0.04). After 60 months, normal or lower limit of normal (LLN) IGF-I levels were found in 67.9% of patients. 85.5% of patients showed an IGF-I normal or <LLN at any time after PEG start. Most patients with uncontrolled IGF-I levels were on submaximal PEG doses.

CONCLUSIONS

ACROSTUDY carried out with the Spanish cohort confirmed that PEG has a favorable safety and efficacy profile. The percentage of patients considered under control was similar to data reported globally and in other local ACROSTUDY results.

Long-term treatment with pegvisomant for acromegaly: a 10-year experience

BACKGROUND

Efficacy of the GH-receptor antagonist pegvisomant (PEG) has differed between preclinical and observational studies mainly due to dose adjustment and IGF-I normalization criteria. An escape phenomenon has also been described, but its definition and underlying causes have not been fully established.

OBJECTIVE

To re-evaluate the outcomes of long-term PEG in a series of previously published patients and analyse the escape phenomenon.

METHODS

We reviewed all patients with acromegaly resistant to SSA in whom PEG was started as monotherapy, who had been included in a previous publication. We prospectively evaluated 64 (56·3% women) from six tertiary care referral hospitals in Spain, for whom data as of June 2014 were available. Escape to PEG was defined as confirmed loss of biochemical control (IGF-I >1·2xULN), after at least 6 months of previous control with a stable dose of PEG.

RESULTS

Patients were followed up for 13·0 (5·9-34·8) years since diagnosis, and 9·0 (4·1-10·4) years since the first administration of PEG. Fifty-one (89·5%) patients had an adequate IGF-I control at the last follow-up visit, 9 of them without treatment. Tumour growth was reported in 6 of 64 cases (9·4%), none of whom had received prior radiotherapy (P = 0·011). Seven patients died during follow-up. We found 16 escapes in 10 patients (15·6%). We identified potential underlying causes in 9 cases (tumour regrowth, previous treatment modifications, concomitant menopause and change in testosterone administration). The reason was unknown in 7 escapes, which occurred in 6 patients (9·4%). All patients, except one, achieved subsequent biochemical control after treatment adjustment.

CONCLUSIONS

We reassure the efficacy and safety of long-term PEG. An escape phenomenon may occur, but it can be overcome by adjusting therapy.

Prediction of therapy response in acromegalic patients under pegvisomant therapy within the German ACROSTUDY cohort

PURPOSE

This study aimed at investigating predicting factors for therapy response under growth hormone receptor antagonist therapy with a focus on subjective and patient-oriented measures.

METHODS

Observational, multicenter nested-cohort study including 271 selected patients with the diagnosis of acromegaly and a minimum of one-year follow-up period within the German ACROSTUDY cohort (total cohort: n = 514). Outcome measures were the change of the biomarker IGF-1 (IGF-1 change and IGF-1 normalisation) between baseline and after 1 year of pegvisomant therapy (12 ± 6 months). Main predictors were patient-assessed subjective measures according to the Patient-Assessed Acromegaly Symptom Questionnaire (PASQ) in conjugation with age, gender, BMI, max. dosage of pegvisomant at follow-up and IGF-1 before the start of pegvisomant therapy.

RESULTS

The mean age of the study population was 51.2 (13.9) years and the mean BMI was 29.5 (5.1) kg/m(2). In adjusted analyses, none of the individual perceived health (PASQ) scores, but age, BMI and IGF-1 at baseline were predictive for an IGF-1 decrease after 1 year of pegvisomant therapy and BMI and IGF-1, but equally none of the PASQ items, were predicting IGF-1 normalisation.

CONCLUSIONS

Age, BMI and baseline IGF-1 but not subjective perceived health measures predict therapy response under second line medical therapy with pegvisomant.

Pegvisomant in combination with long-acting somatostatin analogues in acromegaly: the role of the GH receptor deletion of exon 3

BACKGROUND

Doses of the GH receptor (GHR) antagonist pegvisomant (PEGV) that normalize insulin-like growth factor 1 (IGF1) levels vary widely among acromegaly patients. Predictors for PEGV response are baseline IGF1 levels, sex, body weight and previous radiotherapy. A GHR polymorphism lacking exon 3 (d3-GHR) is frequent in the general population. The influence of d3-GHR on PEGV responsiveness in acromegaly is unclear.

OBJECTIVE

To assess the influence of d3-GHR on IGF1 levels and PEGV responsiveness in acromegaly patients using combined PEGV and long-acting somatostatin receptor ligand (LA-SRIF) treatment.

DESIGN

Data were collected at the Rotterdam Pituitary Centre between 2004 and 2013. Patients with elevated IGF1 levels (>1.2 upper limit of normal; n=112) and over 6 months of high-dose LA-SRIF treatment were co-treated with PEGV. GHR genotype was assessed using genomic DNA in 104 patients.

RESULTS

D3-GHR was observed in 51 (49.0%) of the patients (7.7% homozygous, 41.3% heterozygous) and was in Hardy-Weinberg equilibrium (P=0.859). Baseline characteristics were similar in d3-GHR and full-length (fl)-GHR genotypes. During PEGV/LA-SRIF treatment IGF1 levels were not different between d3-carriers and non-carriers. Similarly, no difference in PEGV dose required to normalize IGF1 (P=0.337) or PEGV serum levels (P=0.433) was observed between the two groups. However, adenoma size decreased significantly (>20% of largest diameter) in 25.6% of the fl-GHR genotype but only in 7.5% of d3-carriers (P=0.034, OR: 4.6 (CI: 1.1-18.9)).

CONCLUSIONS

GHR genotype does not predict the IGF1 normalizing dose of PEGV in acromegaly patients using combination PEGV/LA-SRIF treatment. However, fewer d3-carriers showed significant reductions in adenoma size.

Outcome of complications in acromegaly patients after long-term disease remission

Acromegaly patients suffer from pathologically high growth hormone (GH) and IGF-1 levels that in 99% of cases is due to a GH-producing pituitary adenoma. During active disease, GH excess is associated with a number of pathological conditions, such as hypertension, hypertrophic cardiomyopathy, sleep apnea, arthropathy, vertebral fractures and insulin resistance. After adequate treatment in the form of transsphenoidal surgery, radiotherapy, medical treatment or by a combination of these treatment modalities, several comorbid conditions improve considerably. However, despite long-term biochemical disease control, the prevalence of late manifestations of GH excess is high and significantly impair quality of life. In addition, there is evidence that adequate treatment is not able to normalize mortality risk in these patients. In this review, we critically evaluate the long-term consequences of acromegaly after treatment, focusing on comorbid conditions, quality of life and mortality. We also discuss ongoing challenges in the management of acromegaly patients.

ACROSTUDY: the Italian experience

ACROSTUDY is a world-wide non-interventional, post marketing surveillance study performed to monitor the safety and outcomes of pegvisomant (PEG) in clinical practice. We report data from acromegaly patients who have been included in the Italian ACROSTUDY registry. The data of 341 acromegaly patients (171 males) were available for analysis using data freeze (12/9/2012). Patients were enrolled in 25 Italian endocrine centres. Before and during PEG treatment IGF-I, liver enzymes, metabolic parameters, and pituitary MRI were assessed. Before PEG, 54.3% patients had been treated with medical therapy and surgery, 22.9% medical therapy only, and 15.8% medical plus radiation and surgical therapy. 199 adverse events were reported in 98 patients (28.7%). Serious adverse events were documented in 29 patients (8.5%). 71.1% of patients had no significant change in tumor volume. Central MRI reading was performed in 34 patients; in 7 patients, an increase in tumor volume was found. Hormonal efficacy progressively increased since the start of PEG. After 6 years, normal IGF-I levels were found in 70.9% of patients (mean daily dose 18.1 mg). 87.1% of patients were treated with daily PEG although in 8.8% of patients, it was administered 2-6 times per week and in 3.8% with weekly injections. 74.8% received a PEG dose 10-15 mg/daily. PEG is a drug with a favorable safety profile which is efficacious also considering that in Italy it is currently available as third-line therapy.

Escape and lipodystrophy in acromegaly during pegvisomant therapy, a retrospective multicentre Spanish study

BACKGROUND

Pegvisomant is an effective treatment for acromegaly.

OBJECTIVE

To investigate escape (loss of biochemical control in patients previously controlled) and lipodystrophy in acromegalic patients treated with pegvisomant and to evaluate possible associations with clinical features.

PATIENTS AND METHODS

Multicentre retrospective study involving 19 Spanish centres.

RESULTS

Ninety-seven patients were included (59% women, mean age at diagnosis 42 ± 13 years, 80% macroadenomas); mean follow-up on pegvisomant was 5 ± 2·5 years, and 89 (92%) achieved normal IGF-1. Escape was reported in 30/89 (34%) of responders, after a mean treatment duration of 25 ± 21 months. The mean initial dose of pegvisomant was 11 ± 5 mg/day, and mean dose at escape was 14 ± 7 mg/day. Most patients (26/30, 87%) achieved control with dose increase (57%), additional medical treatment (3%) or both (27%). Mean new dose that controlled IGF-1 after escape was 20 ± 7 mg/day. Treatments associated were somatostatin analogues (SSA in 47%), cabergoline (CAB in 47%) and both (6%). Lipodystrophy was observed in 15 patients (13 females), mild in six, moderate in six, severe in three and persistent in four. Among patients with lipodystrophy, three escaped and three were nonresponders to pegvisomant. Four patients discontinued the drug, and four had dose reductions because of lipodystrophy. It tended to be more frequent in females (P = 0·06) and in patients treated with triple association SSA+CAB+PEG (P = 0·018). No relationship between escape and clinical variables was found, except prior CAB (P = 0·04) and metformin treatment (0·02) and grade of lipodystrophy (P = 0·02).

CONCLUSIONS

A significant proportion of patients treated with pegvisomant escaped (34%); however, the majority (87%) was easily controlled with either dose increase, further medical treatment or both. Lipodystrophy developed in 15%, mostly females, and influenced the response to treatment.

Circulating levels of pegvisomant and endogenous growth hormone during prolonged pegvisomant therapy in patients with acromegaly

OBJECTIVE

To investigate whether pegvisomant treatment in acromegaly induces gradual elevations in endogenous serum growth hormone (GH) levels and whether serum pegvisomant levels predict the therapeutic outcome.

PATIENTS AND METHODS

Seventeen patients (6 women), mean age 46·3 years (range: 23·2-76·2), were studied. For each patient, four hospital visits were identified including 'active disease' (no treatment) and last follow-up. At each visit, 12 blood samples were drawn during 3 h including an oral glucose tolerance test (OGTT). Eight patients received a somatostatin analogue in addition to pegvisomant on the last visit.

RESULTS

Median (range) pegvisomant doses (mg/day) were 10 (10-10), 15 (10-15) and 15 (10-15) at visits 2, 3 and 4, respectively, and the mean duration of pegvisomant treatment was 17·5 ± 3·2 (SEM) months. Serum IGF-I changed significantly during the treatment period with the highest level at baseline and lowest levels at visits 3 and 4. GH levels increased in a dose-dependent manner during pegvisomant treatment and decreased at visit 4. Changes in IGF-I levels correlated negatively with changes in serum pegvisomant levels between visits. Serum pegvisomant at each visit correlated with baseline growth hormone levels, whereas no associations between serum pegvisomant and either dose, gender, age or body weight were found.

CONCLUSIONS

(1) Serum GH levels increased initially, but remained stable during prolonged pegvisomant treatment in patients with acromegaly, (2) serum pegvisomant levels predicted the reduction in serum IGF-I during treatment and (3) the interindividual variation in serum pegvisomant levels seems not predicted by either age, gender or body composition.

Long-term treatment of somatostatin analog-refractory growth hormone-secreting pituitary tumors with pegvisomant alone or combined with long-acting somatostatin analogs: a retrospective analysis of clinical practice and outcomes

Background

Pegvisomant (PEGV) is widely used, alone or with somatostatin analogs (SSA), for GH-secreting pituitary tumors poorly controlled by SSAs alone. No information is available on specific indications for or relative efficacies of PEGV?+?SSA versus PEGV monotherapy. Aim of our study was to characterize real-life clinical use of PEGV vs. PEGV?+?SSA for SSA-resistant acromegaly (patient selection, long-term outcomes, adverse event rates, doses required to achieve control).

Methods

A retrospective analysis of data collected in 2005–2010 in five hospital-based endocrinology centers in Rome was performed. Sixty-two adult acromegaly patients treated ≥6 months with PEGV (Group 1, n?=?35) or PEGV?+?SSA (Group 2, n?=?27) after unsuccessful maximal-dose SSA monotherapy (≥12 months) were enroled. Groups were compared in terms of clinical/biochemical characteristics at diagnosis and before PEGV or PEGV?+?SSA was started (baseline) and end-of-follow-up outcomes (IGF-I levels, adverse event rates, final PEGV doses).

Results

Group 2 showed higher IGF-I and GH levels and sleep apnea rates, higher rates residual tumor tissue at baseline, more substantial responses to SSA monotherapy and worse outcomes (IGF-I normalization rates, final IGF-I levels). Tumor growth and hepatotoxicity events were rare in both groups. Final daily PEGV doses were similar and significantly increased with treatment duration in both groups.

Conclusions

PEGV and PEGV?+?SSA are safe, effective solutions for managing SSA-refractory acromegaly. PEGV?+?SSA tends to be used for more aggressive disease associated with detectable tumor tissue. With both regimens, ongoing monitoring of responses is important since PEGV doses needed to maintain IGF-I control are likely to increase over time.

Recent advancements in the drug treatment of endocrine diseases

Recent years have seen several advances in the management of endocrine diseases. These include novel drugs developed as a consequence of better understanding of the pathophysiology of endocrine conditions, as well as improved delivery methods for existing drugs. In this article, we summarise recent studies evaluating several drugs used in the treatment of endocrine disorders.

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.

Comparative effectiveness review of treatment options for pituitary microadenomas in acromegaly

OBJECT

Acromegaly, a syndrome of excess growth hormone (GH) secretion typically caused by a GH-secreting pituitary adenoma, reduces life expectancy by approximately 10 years when left untreated. Treatment of acromegaly involves combinations of one or more discrete therapeutic modalities to achieve biochemical control. Unfortunately, data capable of informing decisions among alternate management strategies are presently lacking.

METHODS

The authors performed a comparative effectiveness research (CER) review integrating efficacy, cost, and quality of life (QOL) analysis for treatment strategies comprising various combinations of surgery, radiotherapy, stereotactic radiosurgery, and pharmacotherapy in patients with acromegaly caused by a pituitary microadenoma. A management decision tree was used to identify 5 treatment strategies, each with up to 4 potential treatment steps. Efficacy was assessed using recent literature reports of biochemical control rates for each modality. Cost estimations were derived from wholesale drug prices and from the Healthcare Cost and Utility Project. Quality of life data were obtained from studies utilizing the Acromegaly Quality of Life Questionnaire.

RESULTS

Individual treatment modalities were analyzed and ranked in each of 3 domains: highest rate of success, lowest cost, and highest QOL, and these scores were combined to facilitate comparison of overall effectiveness of each of the management strategies. These aggregate effectiveness scores were used to compare the 5 strategies from the decision tree, and a novel strategy was also proposed.

CONCLUSIONS

The choice of management strategy must be individualized for each patient with acromegaly. This CER analysis provides a comprehensive framework to inform clinical decisions among alternate management strategies in patients with GH-secreting pituitary microadenomas.

Pegvisomant: current and potential novel therapeutic applications

BACKGROUND

Pegvisomant is a genetically engineered molecule, which exhibits specific growth hormone (GH) antagonism by directly interacting with the GH receptor. It is currently licensed for the treatment of acromegaly where surgery and medical therapy with somatostatin analogues have failed.

OBJECTIVE

To delineate the role of pegvisomant in the treatment of acromegaly and its novel application in other areas of clinical medicine where suppression of GH action may be of therapeutic benefit.

METHODS

A literature review from PubMed- and EMBASE-listed publications and the web-sites of licensing organisations for medicinal products.

CONCLUSION

Pegvisomant is currently used as a second line therapy in the management of acromegaly. It is highly effective in suppressing the metabolic effects of elevated GH levels when used alone or in combination with somatostatin analogues. However, its long term efficacy and safety for this indication has yet to be established. Preliminary data indicate that pegvisomant may have a role in management of type 1 diabetes with beneficial effects on insulin sensitivity and in preventing the progression of microvascular complications. Additional roles as an adjunct to cancer chemotherapy regimens and for the diagnosis of GH deficiency have been proposed, but have yet to be confirmed.

Clinical effectiveness and cost-effectiveness of pegvisomant for the treatment of acromegaly: a systematic review and economic evaluation

BACKGROUND

Acromegaly, an orphan disease usually caused by a benign pituitary tumour, is characterised by hyper-secretion of growth hormone (GH) and insulin-like growth factor I (IGF-1). It is associated with reduced life expectancy, cardiovascular problems, a variety of insidiously progressing detrimental symptoms and metabolic malfunction. Treatments include surgery, radiotherapy and pharmacotherapy. Pegvisomant (PEG) is a genetically engineered GH analogue licensed as a third or fourth line option when other treatments have failed to normalise IGF-1 levels.

METHODS

Evidence about effectiveness and cost-effectiveness of PEG was systematically reviewed. Data were extracted from published studies and used for a narrative synthesis of evidence. A decision analytical economic model was identified and modified to assess the cost-effectiveness of PEG.

RESULTS

One RCT and 17 non-randomised studies were reviewed for effectiveness. PEG substantially reduced and rapidly normalised IGF-1 levels in the majority of patients, approximately doubled GH levels, and improved some of the signs and symptoms of the disease. Tumour size was unaffected at least in the short term. PEG had a generally safe adverse event profile but a few patients were withdrawn from treatment because of raised liver enzymes. An economic model was identified and adapted to estimate the lower limit for the cost-effectiveness of PEG treatment versus standard care. Over a 20 year time horizon the incremental cost-effectiveness ratio was pound81,000/QALY and pound212,000/LYG. To reduce this to pound30K/QALY would require a reduction in drug cost by about one third.

CONCLUSION

PEG is highly effective for improving patients' IGF-1 level. Signs and symptoms of disease improve but evidence is lacking about long term effects on improved signs and symptoms of disease, quality of life, patient compliance and safety. Economic evaluation indicated that if current standards (UK) for determining cost-effectiveness of therapies were to be applied to PEG it would be considered not to represent good value for money.

Long-term experience of pegvisomant therapy as a treatment for acromegaly

AIMS

To evaluate the long-term efficacy and safety of pegvisomant as a treatment for acromegaly.

DESIGN

Retrospective analysis of clinical and trial data from all patients treated with pegvisomant since 1997 at two centres with common protocols.

RESULTS

Fifty-seven patients (age range 27-78 years) have been treated with pegvisomant since 1997 for up to 91 months (median 18 months). Before commencing pegvisomant, patients had an IGF-I above the upper limit of normal (ULN) of the age-related reference range (median 1.8 x ULN, range 1.2-4.1). Ninety-five per cent normalized IGF-I using a median dose of 15 mg daily (range 10 mg alternate day to 60 mg daily) with no influence of gender on dose requirement. Five patients had combination therapy with either somatostatin analogues (SSA) or cabergoline. Two patients initially controlled on 10 mg and 20 mg required dose increases (to 20 mg + 40 mg) over 24 months to reduce IGF-I. Twenty-seven patients stopped pegvisomant. Reasons included side-effects [abnormal liver function tests (LFTs)] and patient choice. Two patients developed elevated liver transaminases, which normalized on stopping pegvisomant. Patients had 6-12-monthly pituitary magnetic resonance imaging (MRI) scans. One patient had significant tumour size increase.

CONCLUSION

This long-term experience in 57 patients indicates pegvisomant to be effective, safe and well-tolerated. Raised transaminases occurred within the first month of therapy in two patients, and tumour growth was seen in one patient (tumour was growing prior to pegvisomant). In two patients increasing doses of pegvisomant were required to keep IGF-I within the target range.

Guidelines for acromegaly management: an update

OBJECTIVE

The Acromegaly Consensus Group reconvened in November 2007 to update guidelines for acromegaly management.

PARTICIPANTS

The meeting participants comprised 68 pituitary specialists, including neurosurgeons and endocrinologists with extensive experience treating patients with acromegaly. EVIDENCE/CONSENSUS PROCESS: Goals of treatment and the appropriate imaging and biochemical and clinical monitoring of patients with acromegaly were enunciated, based on the available published evidence.

CONCLUSIONS

The group developed a consensus on the approach to managing acromegaly including appropriate roles for neurosurgery, medical therapy, and radiation therapy in the management of these patients.

Long-term treatment of acromegalic patients resistant to somatostatin analogues with the GH receptor antagonist pegvisomant: its efficacy in relation to gender and previous radiotherapy

CONTEXT

Pegvisomant is an effective treatment for somatostatin analogue-resistant acromegaly, but the determinants defining the response to this treatment are largely unknown.

OBJECTIVE

To investigate the efficacy of pegvisomant treatment in resistant acromegalic patients (e.g. serum IGF1 at least 1.25 x upper normal limit) in a clinical setting and the factors conditioning this response.

DESIGN AND SETTING

A retrospective cross-sectional study performed in six Spanish University hospitals from 2004 to 2007. Patients Forty-four acromegalic patients (61.4% female, mean age: 49+/-14), 95% of whom had undergone pituitary surgery and 61% having received pituitary radiotherapy. The mean follow-up was 22.7+/-11.2 months. Main outcome measures IGF1 levels reflected treatment efficacy, and the influence of gender, age, weight, previous radiotherapy and duration of treatment was assessed.

RESULTS

IGF1 normalisation was achieved in 84% of the patients. Male gender (P<0.05), previous irradiation (P<0.05) and the treatment duration (r=0.364, P<0.02) were associated with a better response to pegvisomant therapy. There was a significant decrease in HbA1c (P<0.001) and in the mean insulin dose (P<0.01) in acromegalic diabetic patients. Although 25% of patients experienced mild adverse events, pegvisomant was only withdrawn in four patients due to side effects (two cases of tumour growth, one liver dysfunction and one headache).

CONCLUSIONS

Long-term pegvisomant is a very effective therapy in resistant acromegaly. Male gender and prior radiotherapy influence the therapeutic response rate.

Pituitary-independent effect of octreotide on IGF1 generation

BACKGROUND

Somatostatin analogues are frequently used for medical treatment of acromegaly. The rationale for their use is based on the inhibition of pituitary GH secretion; however, there is in vitro evidence that octreotide also acts to inhibit hepatic IGF1 generation.

AIM & DESIGN

We studied the pituitary-independent effects of octreotide on IGF1 generation in 11 severely GH-deficient (GHD) humans (age 38, range 23-52; seven males; body mass index 24.7+/-3 kg/m(2); peak-stimulated GH <3 microg/l; 3+/-1 pituitary hormone deficiencies) on a stable dose of GH replacement (0.4+/-0.1 mg) for at least 6 months. Patients were studied before and after 50 microg of s.c. octreotide three times a day for 7 days.

RESULTS

At study entry, all patients had total IGF1 within age- and gender-related reference range (SDS 0.4+/-1.0). Octreotide treatment resulted in a significant decrease in total IGF1 (by 18%, 208+/-89 vs 173+/-62 microg/l, P=0.04), free IGF1 (by 13%, 0.83+/-0.36 vs 0.70+/-0.33 microg/l, P=0.01) and IGFBP3 (6%, 4475+/-745 vs 4209+/-912 microg/l, P=0.02). Octreotide suppressed fasting insulin from 8.1+/-3.4 to 6.3+/-4.1 mU/l (P=0.01) and was associated with an increase in fasting glucose from 5.2+/-0.9 to 5.8+/-0.9 mmol/l (P<0.01). IGFBP1 increased by 84% from 42+/-26 to 95+/-52 microg/l (P=0.04).

CONCLUSION

Our study demonstrates that octreotide induces a significant decrease in IGF1 in severely GHD adults on a fixed dose of GH replacement. This is the evidence for a non-pituitary action of octreotide on the GH/IGF1 axis, most likely by antagonising the action of GH on hepatic IGF1 generation and indirectly, by suppressing insulin secretion.

Growth hormone receptor polymorphism and the effects of pegvisomant in acromegaly

BACKGROUND

Sensitivity to pegvisomant therapy is highly variable in patients with acromegaly but determinants of this variability are still unknown. Lack of exon 3 (d3-) of the growth hormone (GH) receptor (GHR) has been associated with increased biological activity of GH.

OBJECTIVE

To assess whether the presence of d3-GHR haplotype may have a role in predicting dose regimen and response to pegvisomant in acromegaly.

DESIGN

Case series. Setting Institutional referral center at a tertiary care hospital. Patients Nineteen acromegalic patients with active disease after unsuccessful neurosurgery and somatostatin analog therapy.

MEASUREMENTS

Before and 1, 3, 6 and 12 months after treatment with pegvisomant, IGF-I; GH receptor genotype, determined from peripheral blood by polymerase chain reaction. All patients started treatment with pegvisomant at 10 mg/daily and then increased the dose, according to a fixed schedule, during a 12-month follow-up until normalization of IGF-I levels.

RESULTS

d3-GHR patients required a significant lower dose of pegvisomant and shorter treatment time to normalize IGF-I.

CONCLUSION

The GHR genotype could be useful in predicting dose and individual response to pegvisomant in acromegaly.

Current thinking on the management of the acromegalic patient

PURPOSE OF REVIEW

Although the concept that acromegaly is associated with heightened cardiovascular risk is not new, it has become apparent that there are a number of risk factors associated with this disease and that specific therapeutic modalities may have variable effects on these risk factors. In addition, it is important to understand the medical therapies available for acromegaly and their role in acromegaly management.

RECENT FINDINGS

Acromegaly is associated with heightened cardiovascular risk, including derangements in glucose homeostasis and lipids, but also in markers of vascular function. Recent studies have demonstrated treatment-specific effects on these markers. In addition, recent studies have detailed further the efficacy and safety of various therapeutic options, in particular that of pegvisomant, the growth hormone receptor antagonist. A role for medical therapy as primary, de-novo therapy has been considered and recent studies support such use.

SUMMARY

The goals of acromegaly therapy are to control excess growth hormone secretion and limit, if not reverse, the long-term medical consequences and risk of premature mortality associated with acromegaly. It is critical to control both the growth hormone hypersecretion and associated cardiovascular risk factors to prevent the associated risks of cardiovascular disease and enhanced mortality. Medical therapy has an important adjuvant role in the management of acromegaly and use of somatostatin analogs as first-line therapy for specific groups of patients should be considered.