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

Investigational drugs for the treatment of acromegaly: new agents to transform therapy

INTRODUCTION

Disease control is essential to decrease morbidity burden and mortality in acromegaly patients. In the last decades, the availability of new drugs increased the rate of disease control. However, up to 55% of patients remain uncontrolled despite available treatment strategies in real-world data. The reasons for this finding may include poor adherence, inadequate tolerability, therapeutic inertia, and high costs. Since acromegaly is a chronic disease and medical therapy is usually life-long, patient's adherence to treatment is fundamental in both achieving and maintaining disease control. Less invasive routes of administration could improve adherence and concur to increase disease control rate.

AREAS COVERED

The aim of current review is to provide a detailed update about investigational drugs for acromegaly treatment currently under investigation as paltusotine, ONO-5788, AP102, GT-02037, ISIS 766720, CAM2024, Lanreotide PRF, DP1038, MTD201, solid dose injection of octreotide.

EXPERT OPINION

Medical therapy of acromegaly is an evolving field. Current studies are addressing patient's need for both new molecules and less invasive routes of administration for already existing drugs. It cannot be ruled out that drugs currently used for other diseases such as cancer could be considered in the future for the treatment of acromegaly.

Past, Present, and Future of Therapies for Pituitary Neuroendocrine Tumors: Need for Omics and Drug Repositioning Guidance

Innovation roadmaps are important, because they encourage the actors in an innovation ecosystem to creatively imagine multiple possible science future(s), while anticipating the prospects and challenges on the innovation trajectory. In this overarching context, this expert review highlights the present unmet need for therapeutic innovations for pituitary neuroendocrine tumors (PitNETs), also known as pituitary adenomas. Although there are many drugs used in practice to treat PitNETs, many of these drugs can have negative side effects and show highly variable outcomes in terms of overall recovery. Building innovation roadmaps for PitNETs' treatments can allow incorporation of systems biology approaches to bring about insights at multiple levels of cell biology, from genes to proteins to metabolites. Using the systems biology techniques, it will then be possible to offer potential therapeutic strategies for the convergence of preventive approaches and patient-centered disease treatment. Here, we first provide a comprehensive overview of the molecular subtypes of PitNETs and therapeutics for these tumors from the past to the present. We then discuss examples of clinical trials and drug repositioning studies and how multi-omics studies can help in discovery and rational development of new therapeutics for PitNETs. Finally, this expert review offers new public health and personalized medicine approaches on cases that are refractory to conventional treatment or recur despite currently used surgical and/or drug therapy.

Octreotide-Resistant Acromegaly: Challenges and Solutions

Acromegaly is a rare and severe disease caused by an increased and autonomous secretion of growth hormone (GH), thus resulting in high circulating levels of insulin-like growth factor 1 (IGF-1). Comorbidities and mortality rate are closely related to the disease duration. However, in most cases achieving biochemical control means reducing or even normalizing mortality and restoring normal life expectancy. Current treatment for acromegaly includes neurosurgery, radiotherapy and medical therapy. Transsphenoidal surgery often represents the recommended first-line treatment. First-generation somatostatin receptor ligands (SRLs) are the drug of choice in patients with persistent disease after surgery and are suggested as first-line treatment for those ineligible for surgery. However, only about half of patients treated with octreotide (or lanreotide) achieve biochemical control. Other available drugs approved for clinical use are the second-generation SRL pasireotide, the dopamine agonist cabergoline, and the GH-receptor antagonist pegvisomant. In the present paper, we revised the current literature about the management of acromegaly, aiming to highlight the most relevant and recent therapeutic strategies proposed for patients resistant to first-line medical therapy. Furthermore, we discussed the potential molecular mechanisms involved in the variable response to first-generation SRLs. Due to the availability of different medical therapies, the choice for the most appropriate drug can be currently based also on the peculiar clinical characteristics of each patient.

Pegvisomant Improves Glucose Metabolism in Acromegaly: A Meta-Analysis of Prospective Interventional Studies

INTRODUCTION

Pegvisomant (PEG) in monotherapy or combined with somatostatin analogs (SSAs) is used to control acromegaly, improving metabolism. However, the metabolic changes induced by PEG have not been systematically reviewed.

OBJECTIVE

To address the following questions: does PEG or the combination of PEG and SSAs affect fasting plasma glucose (FPG), glycosylated Hb (HbA1c), glucose load (2-hour oral glucose tolerance test), insulin levels [fasting plasma insulin (FPI)], homeostatic model assessment of insulin resistance (HOMA-I), homeostatic model assessment of β-cell function, lipid profile, or body mass index? Are the effects disease-related or drug-related?

DATA SOURCES

Indexed databases up to January 2019.

STUDY SELECTION

Prospective interventional trials reporting glycometabolic outcomes under PEG or PEG plus SSAs for a minimum of 6 months.

DATA EXTRACTION

Three reviewers screened eligible publications (7248), three others extracted the outcomes, and all assessed the risk of biases.

DATA SYNTHESIS

Thirteen studies were included in the PEG and 5 in the PEG plus SSAs analysis (overall 550 subjects). PEG significantly decreased FPG [effect size (ES) -0.80 mmol/L (95% CI, -1.06 to -0.55); P = 0.000], HbA1c [ES -0.43% (95% CI, -0.56 to -0.31); P = 0.000], FPI [ES -5.31 mU/L (95% CI, -10.23 to -0.39); P = 0.034], and HOMA-I [ES -0.61 (95% CI, -1.17 to -0.04); P = 0.034]. Effects on FPG and FPI were not correlated to IGF-1 changes. The addition of PEG to SSAs mitigated the effects of SSAs on metabolism, producing an overall neutral effect.

CONCLUSIONS

Independently of disease control, PEG in monotherapy or combined with SSAs seems to improve glucose metabolism, reducing FPG, HbA1c, FPI, and HOMA-I.

AIP and MEN1 mutations and AIP immunohistochemistry in pituitary adenomas in a tertiary referral center

BACKGROUND

Pituitary adenomas have a high disease burden due to tumor growth/invasion and disordered hormonal secretion. Germline mutations in genes such as MEN1 and AIP are associated with early onset of aggressive pituitary adenomas that can be resistant to medical therapy.

AIMS

We performed a retrospective screening study using published risk criteria to assess the frequency of AIP and MEN1 mutations in pituitary adenoma patients in a tertiary referral center.

METHODS

Pituitary adenoma patients with pediatric/adolescent onset, macroadenomas occurring ≤30 years of age, familial isolated pituitary adenoma (FIPA) kindreds and acromegaly or prolactinoma cases that were uncontrolled by medical therapy were studied genetically. We also assessed whether immunohistochemical staining for AIP (AIP-IHC) in somatotropinomas was associated with somatostatin analogs (SSA) response.

RESULTS

Fifty-five patients met the study criteria and underwent genetic screening for AIP/MEN1 mutations. No mutations were identified and large deletions/duplications were ruled out using MLPA. In a cohort of sporadic somatotropinomas, low AIP-IHC tumors were significantly larger (P = 0.002) and were more frequently sparsely granulated (P = 0.046) than high AIP-IHC tumors. No significant relationship between AIP-IHC and SSA responses was seen.

CONCLUSIONS

Germline mutations in AIP/MEN1 in pituitary adenoma patients are rare and the use of general risk criteria did not identify cases in a large tertiary-referral setting. In acromegaly, low AIP-IHC was related to larger tumor size and more frequent sparsely granulated subtype but no relationship with SSA responsiveness was seen. The genetics of pituitary adenomas remains largely unexplained and AIP screening criteria could be significantly refined to focus on large, aggressive tumors in young patients.

The role of combination medical therapy in the treatment of acromegaly

PURPOSE

Uncontrolled acromegaly results in approximately 2-fold excess mortality. Pituitary surgery is first-line therapy, and medical treatment is indicated for persistent disease. While cabergoline and pegvisomant are used in select patients, somatostatin receptor ligands (SRLs) remain the cornerstone of medical treatment. Management of patients poorly responsive to SRLs is therefore, challenging. The purpose of this review is to highlight the options for combination medical therapy in the treatment of acromegaly, with an emphasis on efficacy and safety.

METHODS

All original articles/abstracts detailing combination medical therapy in acromegaly were identified from a PubMed search.

RESULTS

Studies reviewed included retrospective and open-label prospective studies. While the combination of SRL and cabergoline was generally well tolerated, a lower baseline insulin-like growth factor-1 (IGF-1) level was the best predictor of efficacy; this combination may be most effective in patients with mildly elevated IGF-1. SRL-pegvisomant combination normalized IGF-1 in the majority of patients; continued efficacy despite individual drug dosing reduction was also reported. The risk of significant liver enzyme elevation was, however, higher than that reported with SRL monotherapy; close monitoring is recommended. Data on pegvisomant-cabergoline combination is limited, but this may be an option in the setting of SRL intolerance. Reports on temozolomide used in combination with other medical therapies in patients with aggressive GH-secreting tumors are also summarized.

CONCLUSION

While more prospective, randomized controlled trials on long-term efficacy and safety are needed, combination medical therapy remains a treatment strategy that should be considered for acromegaly patients poorly responsive to SRLs.

Combined treatment with octreotide LAR and pegvisomant in patients with pituitary gigantism: clinical evaluation and genetic screening

INTRODUCTION

Pituitary gigantism is a rare condition caused by growth hormone secreting hypersecretion, usually by a pituitary tumor. Acromegaly and gigantism cases that have a genetic cause are challenging to treat, due to large tumor size and poor responses to some medical therapies (e.g. AIP mutation affected cases and those with X-linked acrogigantism syndrome).

MATERIALS AND METHODS

We performed a retrospective study to identify gigantism cases among 160 somatotropinoma patients treated between 1985 and 2015 at the University Hospital of Caracas, Venezuela. We studied clinical details at diagnosis, hormonal responses to therapy and undertook targeted genetic testing. Among the 160 cases, eight patients (six males; 75 %) were diagnosed with pituitary gigantism and underwent genetic analysis that included array comparative genome hybridization for Xq26.3 duplications.

RESULTS

All patients had GH secreting pituitary macroadenomas that were difficult to control with conventional treatment options, such as surgery or primary somatostatin receptor ligand (SRL) therapy. Combined therapy (long-acting SRL and pegvisomant) as primary treatment or after pituitary surgery and radiotherapy permitted the normalization of IGF-1 levels and clinical improvement. Novel AIP mutations were the found in three patients. None of the patients had Xq26.3 microduplications.

CONCLUSIONS

Treatment of pituitary gigantism is frequently challenging; delayed control increases the harmful effects of GH excess, such as, excessive stature and symptom burden, so early diagnosis and effective treatment are particularly important in these cases.

Update on the use of oral octreotide therapy for acromegaly

Somatostatin analogs are most commonly used in pharmacological treatment of acromegaly. Pegvisomant and dopamine agonists are alternatives, which are used to a lesser extent. Dopamine agonists are the only orally applicable medication but are less effective than the other options. For a large number of patients, life-long pharmacotherapy has to be applied and frequent injections represent a reduction of quality of life for many of them. Areas covered: Recently published evidence for the use of oral octreotide therapy for acromegaly. Expert commentary: Oral octreotide is a novel and effective treatment for acromegaly and the side effects have been shown to be comparable to the injectable SSAs. The combination with a transient permeability enhancer allows intestinal permeation but also enables molecules with a size <70 kDa to pass transiently. This does not seem to have an acute or subacute consequence, but the long-term effect is still elusive. Therefore, more long-term trials are desirable.

Combined treatment of somatostatin analogues with pegvisomant in acromegaly

Treatment of acromegaly with monotherapy long-acting somatostatin analogues (LA-SSA) as primary treatment or after neurosurgery can only achieve complete normalization of insulin-like growth factor I (IGF-I) in roughly 40 % of patients. Recently, one of the acromegaly consensus groups has recommended switching to combined treatment of LA-SSA and pegvisomant (PEGV) in patients with partial response to LA-SSAs. This combination of LA-SSA and PEGV, a growth hormone receptor antagonist, can normalize IGF-I levels in virtually all patients, requiring that the adequate dose of PEGV is used. The required PEGV dose varies significantly between individual acromegaly patients. One of the advantages of the combination therapy is that tumor size control or even tumor shrinkage can be observed in a vast majority of patients. The main side effects of the combination treatment are gastrointestinal symptoms, lipohypertrophy and transient elevated liver transaminases. In this review we provide an overview of the efficacy and safety of the combined treatment of LA-SSAs with PEGV.

Patterns of pharmacologic treatment in US patients with acromegaly

OBJECTIVE

To establish a baseline pattern of care across academic and community settings, it is important to examine the contemporary treatment of acromegaly. We characterized medical treatment patterns for acromegaly in the US to develop a basis for tracking concordance with guidelines.

RESEARCH DESIGN AND METHODS

Acromegaly patients were identified in two commercial claims databases for this retrospective analysis. Study subjects had ≥2 medical claims with acromegaly (ICD-9-CM code 253.0) and ≥1 claim for pharmacotherapy (bromocriptine, cabergoline, octreotide SA, octreotide LAR, lanreotide, or pegvisomant) in the study timeframe (1 January 2002-31 December 2013). Patients were considered newly treated if they were continuously enrolled for ≥6 months before first observed treatment and had no claim for pharmacologic treatment during that time. Outcomes included various pharmacotherapies, including combination treatments, and differences between lines of therapy.

RESULTS

A total of 3150 patients had ≥1 pharmacotherapy (mean age: 46.5 years; 50.1% were female); 1471 were newly treated. Somatostatin receptor ligands (SRLs) were the most common drug class used first line (57.2%); cabergoline (27.8%) was the most common treatment, followed by octreotide LAR (22.3%) and lanreotide (19.7%). SRLs were also the most commonly used second-line (42.8%) and third-line pharmacotherapies (43.9%), with combination therapy (23.2%) and octreotide LAR (19.8%) as the most commonly used treatments, respectively.

CONCLUSIONS

This study, representing the largest claims-based analysis of acromegaly to date, used two databases across a 12 year period to examine complex treatment patterns in a difficult-to-study disease. Although wide variation in acromegaly treatment patterns exists in US clinical practice, in first-line, second-line, and third-line therapy, SRL was the most commonly used drug class. Drug combinations also varied considerably across lines of therapy. The switching between different monotherapies and varied use of drugs in combination may suggest an unmet need for alternative treatment options. Our claims-based technique of examining treatment patterns may be used for other rare diseases, although high censoring rates may be a challenge.

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.

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.

Clinical applications of somatostatin analogs for growth hormone-secreting pituitary adenomas

Excessive growth hormone (GH) is usually secreted by GH-secreting pituitary adenomas and causes gigantism in juveniles or acromegaly in adults. The clinical complications involving cardiovascular, respiratory, and metabolic systems lead to elevated morbidity in acromegaly. Control of serum GH and insulin-like growth factor (IGF) 1 hypersecretion by surgery or pharmacotherapy can decrease morbidity. Current pharmacotherapy includes somatostatin analogs (SAs) and GH receptor antagonist; the former consists of lanreotide Autogel (ATG) and octreotide long-acting release (LAR), and the latter refers to pegvisomant. As primary medical therapy, lanreotide ATG and octreotide LAR can be supplied in a long-lasting formulation to achieve biochemical control of GH and IGF-1 by subcutaneous injection every 4-6 weeks. Lanreotide ATG and octreotide LAR provide an effective medical treatment, whether as a primary or secondary therapy, for the treatment of GH-secreting pituitary adenoma; however, to maximize benefits with the least cost, several points should be emphasized before the application of SAs. A comprehensive assessment, especially of the observation of clinical predictors and preselection of SA treatment, should be completed in advance. A treatment process lasting at least 3 months should be implemented to achieve a long-term stable blood concentration. More satisfactory surgical outcomes for noninvasive macroadenomas treated with presurgical SA may be achieved, although controversy of such adjuvant therapy exists. Combination of SA and pegvisomant or cabergoline shows advantages in some specific cases. Thus, an individual treatment program should be established for each patient under a full evaluation of the risks and benefits.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Investigational therapies for acromegaly

INTRODUCTION

The treatment of acromegaly aims at normalizing growth hormone (GH) and insulin-like growth factor (IGF-I) levels and controlling tumor growth. The approaches to therapy are essentially three: surgery and pharmacotherapy, alone or in combination, and radiotherapy, generally used in more aggressive tumors.

AREAS COVERED

This review focuses on the novel drug formulations being developed for medical therapy of acromegaly. Even though many efficient treatments have been made available to manage acromegaly in the last two decades, a significant number of patients remain still uncontrolled. Medical therapy represents an important therapeutic option and can be used as the first-line treatment in many patients. However, roughly 25% of patients might be considered as poor responsive or resistant to conventional long-acting somatostatin analogs (SSA) treatment. Therefore, new longer-acting SSA, oral SSA formulations, new combined therapies with weekly doses of pegvisomant, combination therapy with pegvisomant (PEG) and cabergoline (CAB) or SSA and new approaches have been proposed. New molecules are currently under investigation in clinical trials, such as the SSA multi-receptor ligand, pasireotide, which represents a promising option therapy, especially in patients not adequately controlled with currently available SSA. Further, temozolomide has been suggested as an efficient drug for treating GH-aggressive pituitary tumors resistant to conventional therapy.

EXPERT OPINION

All these novel SSA formulations and new molecules implement the available options in therapies of acromegaly to improve disease control. However, further studies are needed to define the exact role of these newer agents. The predicting factors for response to these new therapies should also be determined.

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.

Clinical experience with lanreotide for the treatment of acromegaly

Acromegaly is a rare disease, characterized in adults by its distinctive appearance of facial dysmorphism and swollen fingers. It is caused by an overproduction of growth hormone (GH) in more than 99% of patients and in nearly all cases is due to a pituitary adenoma. If surgical resection of the adenoma is not effective, medical treatment is usually the next treatment option. The most commonly used medications are the somatostatin analogues octreotide and lanreotide. Lanreotide is a synthetic somatostatin analogue and is available as slow-release microparticle (every 7-14 days) and prolonged-release liquid (autogel, every 28-56 days) formulations. Lanreotide autogel is a supersaturated aqueous formulation for deep subcutaneous injection and is sold in a ready-to-use prefilled syringe. This ease of use allows self or partner administration at home. This article reviews the use of lanreotide in the treatment of acromegaly and its advantages and disadvantages compared with other somatostatin analogues.

Lanreotide depot deep subcutaneous injection: a new method of delivery and its associated benefits

Acromegaly is a rare disease characterized by excessive growth hormone secretion, usually from a pituitary tumor. Treatment options include surgery, medical therapy, and in some cases, radiation therapy. Current medical therapy consists of treatment with somatostatin analog medications or a growth hormone receptor antagonist. There are two somatostatin analogs currently in use, octreotide and lanreotide. Both are supplied in long-acting formulations and are of comparable biochemical efficacy. Lanreotide is supplied in a prefilled syringe and is injected into deep subcutaneous tissue. Studies have been conducted to assess the efficacy of self- or partner administration, and have demonstrated that injection of lanreotide can be accomplished reliably and safely outside a physician's office. For patients who have achieved biochemical control with lanreotide, the FDA has recently approved an extended dosing interval. Selected patients may be able to receive the medication less frequently with injections of 120 mg administered every 6 or 8 weeks. This review focuses on the use of lanreotide in the treatment of acromegaly, the safety and efficacy of the drug, and the benefits afforded to patients because of unique aspects of the delivery of lanreotide.

Combination treatment with somatostatin analogues and pegvisomant in acromegaly

Mono-therapy using long-acting somatostatin analogues and surgery cannot provide optimal biochemical control in a large proportion of patients with acromegaly. This results in increased mortality, poor control of signs and symptoms of disease and decreased quality of life. Combined treatment with somatostatin analogues and pegvisomant (a growth-hormone-receptor antagonist) seems to be an attractive option. Combination treatment is highly effective at normalising the level of insulin-like growth factor 1 in over 90% of patients and has a favourable effect on quality of life in those with biochemically controlled acromegaly. Moreover, combination therapy with somatostatin analogues results in a clinically relevant decrease in tumour size in about 20% of patients, whereas pegvisomant (PEG-V) mono-therapy does not decrease pituitary tumour size. Transient elevations in the levels of transaminases are the main adverse effects of combination treatment, which occur in about 11-15% of patients.