Comparison of six months therapy with octreotide versus lanreotide in acromegalic patients: a retrospective study

External Validity of Somatostatin Analogs Trials in Advanced Neuroendocrine Neoplasms: The GETNE-TRASGU Study

INTRODUCTION

Somatostatin analogs (SSA) prolong progression-free survival (PFS) in patients with well-differentiated gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). However, the eligibility criteria in randomized clinical trials (RCTs) have been restricted, which contrasts with the vast heterogeneity found in NENs.

METHODS

We identified patients with well-differentiated (Ki-67% ≤20%), metastatic GEP-NENs treated in first line with SSA monotherapy from the Spanish R-GETNE registry. The therapeutic effect was evaluated using a Bayesian Cox model. The objective was to compare survival-based outcomes from real-world clinical practice versus RCTs.

RESULTS

The dataset contained 535 patients with a median age of 62 years (range: 26-89). The median Ki-67% was 4 (range: 0-20). The most common primary tumor sites were as follows: midgut, 46%; pancreas, 34%; unknown primary, 10%; and colorectal, 10%. Half of the patients received octreotide LAR (n = 266) and half, lanreotide autogel (n = 269). The median PFS was 28.0 months (95% CI: 22.1-32.0) for octreotide versus 30.1 months (95% CI: 23.1-38.0) for lanreotide. The overall hazard ratio for lanreotide versus octreotide was 0.90 (95% credible interval: 0.71-1.12). The probability of effect sizes >30% with lanreotide versus octreotide was 2 and 6% for midgut and foregut NENs, respectively.

CONCLUSION

Our study evaluated the external validity of RCTs examining SSAs in the real world, as well as the main effect-modifying factors (progression status, symptoms, tumor site, specific metastases, and analytical data). Our results indicate that both octreotide LAR and lanreotide autogel had a similar effect on PFS. Consequently, both represent valid alternatives in patients with well-differentiated, metastatic GEP-NENs.

Complications of acromegaly: thyroid and colon

INTRODUCTION

In acromegaly the long-term exposure to high growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels may result in specific complications in different human organs, including the thyroid gland and the colon.

MATERIALS AND METHODS

We will review here the evidence available regarding the characteristic thyroid and colon complications in acromegaly.

RESULTS

This review summarizes the published data observing noncancerous structural abnormalities (thyroid nodules, colonic polyps) and thyroid and colon cancer in patients diagnosed with acromegaly.

CONCLUSION

Thyroid micro-carcinomas are probably over-diagnosed among acromegalic patients. In regard to colon cancer, there is no sufficient data to suggest that colon cancer risk is higher in acromegaly compared to the general population.

Resistance to somatostatin analogs in acromegaly

Somatostatin analogs (SA) are widely used in acromegaly, either as first-line or adjuvant treatment after surgery. First-line treatment with these drugs is generally used in the patients with macroadenomas or in those with clinical conditions so severe as to prevent unsafe reactions during anesthesia. Generally, the response to SA takes into account both control of GH and IGF-I excess, with consequent improvement of clinical symptoms directly related to GH and IGF-I excess, and tumor shrinkage. This latter effect is more prominent in the patients treated first-line and bearing large macroadenomas, but it is also observed in patients with microadenomas, even with little clinical implication. Predictors of response are patients' gender, age, initial GH and IGF-I levels, and tumor mass, as well as adequate expression of somatostatin receptor types 2 and 5, those with the highest affinity for octreotide and lanreotide. Only sporadic cases of somatostatin receptor gene mutation or impaired signaling pathways have been described in GH-secreting tumors so far. The response to SA also depends on treatment duration and dosage of the drug used, so that a definition of resistance based on short-term treatments using low doses of long-acting SA is limited. Current data suggest that response to these drugs is better analyzed taking together biochemical and tumoral effects because only the absence of both responses might be considered as a poor response or resistance. This latter evidence seems to occur in 25% of treated patients after 12 months of currently available long-acting SA.

Therapeutic options in the management of acromegaly: focus on lanreotide Autogel

BACKGROUND

In acromegaly, expert surgery is curative in only about 60% of patients. Postoperative radiation therapy is associated with a high incidence of hypopituitarism and its effect on growth hormone (GH) production is slow, so that adjuvant medical treatment becomes of importance in the management of many patients.

OBJECTIVE

To delineate the role of lanreotide in the treatment of acromegaly.

METHODS

Search of Medline, Embase, and Web of Science databases for clinical studies of lanreotide in acromegaly.

RESULTS

Treatment with lanreotide slow release and lanreotide Autogel((R)) normalized GH and insulin-like growth factor-I (IGF-I) concentrations in about 50% of patients. The efficacy of 120 mg lanreotide Autogel((R)) on GH and IGF-I levels was comparable with that of 20 mg octreotide LAR. There were no differences in improvement of cardiac function, decrease in pancreatic beta-cell function, or occurrence of side effects, including cholelithiasis, between octreotide LAR and lanreotide Autogel(R). When postoperative treatment with somatostatin analogs does not result in normalization of serum IGF-I and GH levels after noncurative surgery, pegvisomant alone or in combination with somatostatin analogs can control these levels in a substantial number of patients.

A critical analysis of clinically available somatostatin analog formulations for therapy of acromegaly

CONTEXT

Short and long-acting somatostatin (SRIF) analogs are approved for clinical use in acromegaly. Recent analysis of the relative efficacy of octreotide LAR and lanreotide SR on the GH-IGF-I axis in acromegaly favored octreotide LAR in the secondary treatment of patients not preselected by SRIF responsiveness. A novel aqueous formulation of lanreotide, lanreotide Autogel (ATG), has recently been approved and is the predominant (and only in the United States) formulation of lanreotide used clinically.

OBJECTIVE

We performed a critical review of SRIF analog treatment to establish the relative efficacy of three clinically available SRIF analog preparations, octreotide LAR, lanreotide SR, and lanreotide ATG (Somatuline depot in the United States) in control of the GH-IGF-I axis in acromegaly.

DATA SOURCES

Data were drawn from MEDLINE and the bibliography of analyses of long-acting SRIF analogs.

DATA COLLECTION

We reviewed the largest studies of sc octreotide, octreotide LAR, and lanreotide SR, all that included biochemical end-point data for lanreotide ATG, and studies that directly compared the efficacy of octreotide LAR and lanreotide SR.

DATA SYNTHESIS

Caveats considered included differences in baseline GH and IGF-I values, patient selection, and interassay and intraassay variability, confounding the analysis. Studies comparing patients treated contiguously with lanreotide SR and octreotide LAR are fraught with methodological problems, however, are suggestive of marginally greater efficacy in control of the GH-IGF-I axis for octreotide LAR. Lanreotide ATG shows noninferiority to lanreotide SR. Five small studies directly comparing octreotide LAR and lanreotide ATG suggest no significant differences between these preparations in control of biochemical end-points.

CONCLUSION

Lanreotide ATG and octreotide LAR are equivalent in the control of symptoms and biochemical markers in patients with acromegaly.

Treatment of postural tachycardia syndrome: a comparison of octreotide and midodrine

We assessed the potency of octreotide and midodrine, and their combination, in the treatment of the postural tachycardia syndrome (POTS) and orthostatic intolerance (OI). Nine patients with POTS and six patients with OI stood for up to 1 hour while their HR and BP were monitored. Patients received on separate days, midodrine 10 mg 1 hour before testing, octreotide 0.9 micro g/kg 8 minutes before testing or combination therapy. Standing time in the patients with POTS was 41.2 +/- 8.4 minutes and not improved by midodrine or octreotide, but increased to 56.3 +/- 2.7 (P < 0.01) minutes following combination therapy. The standing heart rate in POTS, 114 +/- 0.7 bpm, was suppressed by midodrine 92.8 +/- 0.7 (P < 0.001), octreotide 90.6 +/- 0.78 (P < 0.001), and combination therapy 84.7 +/- 0.7 (P < 0.001). Combination therapy was better than monotherapy (P < 0.001) but only for the first 10 minutes of standing. Standing time of 36.3 +/- 3.5 minutes in the patients with OI improved with midodrine, octreotide and combination therapy (55.5 +/- 3.1, 56.5 +/- 3.5, and 56.6 +/- 3.3, respectively, P < 0.05 for each). Standing heart rate in OI was 100 +/- .76 bpm; following midodrine it was 80.3 +/- .69 (P < 0.05), following octreotide it was 84.8 +/- .86, and following combination therapy it was 71.2 +/- .9 (P < 0.01). The RR interval versus time area under the curve (The Orthostatic Index) was 21.1 +/- 4 in patients with OI. After midodrine it was 41.4 +/- 3.5 (P < 0.01), after octreotide 40.3 +/- 3.8 (P < 0.01) and after the combination it was 47.3 +/- 4.6 (P < 0.001). Midodrine and octreotide suppressed tachycardia in POTS and improved standing times in OI. The two drugs had similar potencies; combination therapy was not significantly better than monotherapy.

Current pharmacotherapy for acromegaly: a review

Acromegaly is associated with considerable morbidity and excess mortality; however, after effective treatment, both morbidity and mortality risks improve. Growth hormone excess in acromegaly can be controlled in many patients by pharmacotherapy alone, and with a combination of transsphenoidal surgery and pharmacotherapy in almost all patients. Since the clinical introduction of pegvisomant, a growth hormone-receptor antagonist, the role of radiotherapy is restricted. This review focuses on the treatment options for acromegaly (e.g., surgery, radiotherapy and pharmacotherapy with the depot preparations of the somatostatin analogues octreotide long-acting release formulation, lanreotide slow-release formulation and lanreotide Autogel, the growth hormone antagonist pegvisomant and the dopamine agonist cabergoline). Pharmacological characteristics of these drugs and the clinical and adverse effects are discussed individually and in relation to the other treatment modalities. The evidence for biochemical goals aimed at during medical treatment and the costs of pharmacotherapy are discussed. A new treatment algorithm is proposed, in which the choice between primary medical treatment and primary surgery is individualised, dependent on adenoma size and extension, patient factors (age, preference for therapy, contraindication for surgery), surgical experience of the centre and octreotide sensitivity of the adenoma. The high cost of lifelong medical treatment, especially of pegvisomant, must be weighed against the cost of a single surgical procedure.

Sandostatin LAR in acromegaly: a 6-week injection interval suppresses GH secretion as effectively as a 4-week interval

INTRODUCTION

Depot preparations of long-acting somatostatin analogues are being used increasingly in the treatment of GH hypersecretion in patients with acromegaly, either as primary treatment or as secondary treatment following incomplete surgery. In 60% of these patients, Sandostatin long-acting release (LAR), the depot preparation of octreotide, achieves effective suppression of serum GH (< 5 mU/l) and IGF-I levels. The advice is to administer Sandostatin LAR at 4-week intervals. After injection, serum octreotide shows an initial peak and thereafter maximal values between 14 and 42 days. There have been suggestions that the dose interval of this preparation could be increased, resulting in reduced costs, although this concept has not been confirmed by studies.

AIM OF THE STUDY

We performed a prospective, cohort study in patients with active acromegaly but with normal serum GH and IGF-I levels during Sandostatin LAR treatment to assess whether the dose interval could be safely increased from 4 to 6 weeks, without significant effect on serum GH concentrations or other biochemical and clinical markers of GH hypersecretion.

PATIENTS AND METHODS

Fourteen patients (seven males) with GH concentrations below 5 mU/l during Sandostatin LAR treatment entered an 8-week withdrawal study following an injection. Subsequently, during an interval study patients received injections at 6-week intervals (t = 0, 8, 14, 20, 26, 32, 38 and 44 weeks). Study parameters (fasting GH, average GH of eight plasma samples, IGF-I, and octreotide concentrations, symptoms score and quality-of-life score) were assessed 2, 4, 6 and 8 weeks following the first injection (withdrawal) and at 26 and 44 weeks (interval study) before the next injection.

RESULTS

During the withdrawal study, mean serum GH concentration increased significantly from 1.68 +/- 0.3 at 4 weeks to 2.57 +/- 0.5 mU/l at 6 weeks (P = 0.04, 4 vs. 6 weeks) and to 2.89 +/- 0.4 mU/l at 8 weeks (P < 0.001, 4 vs. 8 weeks). Mean serum GH concentration was below 5 mU/l in all patients at all time points, except for one patient at 8 weeks, and IGF-I levels remained normal in all patients. During withdrawal up to 8 weeks there was no significant change in serum IGF-I concentration, symptoms score or quality-of-life score. Mean serum octreotide decreased significantly from 1610 +/- 355 ng/l at 2 weeks to 1045 +/- 272 ng/l at 6 weeks (P = 0.002, 2 and 4 vs. 6 weeks) and to 559 +/- 147 ng/l at 8 weeks. In the interval study, one patient had mean serum GH above 5 mU/l associated with an increase in symptoms at 26 weeks and she was withdrawn from the study. The remaining 13 patients completed the 6-weekly injection study protocol and in the long term no significant changes in mean serum GH concentration, IGF-I concentration or symptom scores were observed (6 vs. 26 and 44 weeks). All patients had a mean serum GH concentration < 5 mU/l and serum IGF-I remained normal in 11 out of 14 patients at 26 weeks and nine out of 13 patients at 44 weeks. Moreover, the mean octreotide concentrations measured 6 weeks after a Sandostatin LAR injection did not decrease in the long term.

CONCLUSION

On the basis of serum GH concentrations, most patients with serum GH levels < 5 mU/l during Sandostatin LAR treatment using a 4-weekly schedule can be effectively treated with 6-weekly injections. However, during long-term treatment with 6-weekly injections, discordant IGF-I and GH results were observed in 30% of the patients and careful clinical monitoring is therefore required.

Pharmacotherapy or surgery as primary treatment for acromegaly?

In recent years important progress has been made in the management of acromegaly due to the availability of effective and well tolerated drugs and to improved surgical techniques, resulting in a broader choice of therapeutic interventions. Although surgery in the hands of an experienced surgeon still represents the primary option for the majority of patients, the new formulations of somatostatin analogues and dopamine agonists have partially modified the primary therapeutic approach to this severe and disabling chronic disease. Therapy with somatostatin analogues has been shown to reduce morbidity and the mortality rate in patients with acromegaly, and currently in some patients this medical approach may be preferable to surgery. Although in selected patients individualised pharmacotherapy might represent the primary therapy, trans-sphenoidal surgery of microadenomas and noninvasive macroadenomas remains the primary option, since the remission rate is very high and the costs are relatively low in comparison with lifelong therapy with somatostatin analogues. However, the treatment schedule in acromegaly should consider criteria additional to tumour size and invasiveness, such as the age and the general clinical condition of the patient. Presurgical treatment with somatostatin analogues has been reported to reduce surgical complications and time of hospitalisation after the operation. Moreover, a multidisciplinary team of well trained specialists is needed in order to guarantee the most optimal quality of life and life expectancy for patients with acromegaly.

Current management of acromegaly

Acromegaly, a chronic disease of growth hormone (GH) hypersecretion, is most typically caused by a pituitary adenoma. Early diagnosis is critical for prompt intervention to prevent deleterious effects of prolonged exposure to elevated GH and insulin-like growth factor Type I (IGF-I) levels. Current therapy for acromegaly includes several options: surgery, radiotherapy and pharmacotherapy. Transsphenoidal adenomectomy remains a mainstay of therapy for acromegaly. Cure rates are high in microadenomas, but < 50% in macroadenomas. Conventional and stereotactic procedures for radiation therapy are also effective in decreasing GH levels in acromegalic patients, but they need years to normalise GH hypersecretion and carry with them the risk of hypopituitarism. The major classes of drugs currently used to treat acromegaly are dopamine agonists and analogues of somatostatin. Dopamine agonists bind to the D2 receptor and suppress GH hypersecretion in some patients with acromegaly. Their clinical effectiveness is modest, although promising results have been obtained with two novel compounds, quinagolide and cabergoline, that possess long duration of action. Somatostatin analogues have been shown to improve clinical symptoms of acromegaly, decrease hypersecretion of GH and IGF-I and reduce tumour volume in a clinically significant number of patients. Octreotide is administered by s.c. route several times a day, but the recently developed sustained release formulations (octreotide LAR and SR lanreotide) are administered only every 7-28 days by i.m. injections. The complications associated with somatostatin analogues are small, relative to the benefits. Lastly, compounds with a novel mechanism of action, the GH receptor antagonists, are presently under investigation.