Patients
Male and female patients aged 18 to 75 years, with active acromegaly, defined as elevated IGF-1 (≥1.3 × upper limit of normal [ULN]) and GH levels (mean ≥2.5 μg/L; average calculated from samples at 0, 30, 60, 90, and 120 minutes during the screening period) were eligible to participate in the study. Patients were included if they had either surgical removal of the adenoma ≥3 months before screening, or were likely to require pituitary surgery at a later time, but not before completing ≥32 weeks of study treatment (plus an additional 8 weeks for patients in the pharmacokinetic [PK] subgroup), or if pituitary surgery was deemed not an option. For patients receiving replacement therapy with thyroid hormones, levels of thyroid hormones were required to be within the normal range for ≥1 month before screening. For patients receiving corticosteroids and/or sex hormones, the dose of these was required to be stable for ≥1 month before screening.
Patients were excluded if they had received treatment with radiotherapy within the previous 10 years, or if a need for radiotherapy during the study was anticipated. Also excluded were patients who received treatment with short-acting octreotide or bromocriptine within the preceding 2 weeks, lanreotide autogel, lanreotide (lanreotide 40 mg PR; lanreotide PR microparticle), pegvisomant, cabergoline or octreotide LAR within the preceding 3 months, or traditional Chinese medicine within the preceding month. Other reasons for exclusion included use of investigational medicinal products or devices within ≤90 days previously, and/or being scheduled to receive such treatment during the study, defects in visual field according to clinical judgement, or unsuitability for magnetic resonance imaging (MRI). Patients with major cardiovascular diseases, uncontrolled diabetes (glycated hemoglobin [HbA1c] >8.5%), symptomatic gallbladder disease, current concomitant malignancies, or clinically significant renal (creatinine >1.5 × ULN) or hepatic disease (any liver enzyme > 2.5 × ULN) were excluded. In addition, patients with any severe, acute, or chronic medical or psychiatric condition or any laboratory abnormality that might have increased the risk associated with study participation or lanreotide administration, and made the patient inappropriate for entry into the study in the judgement of the investigator, or have interfered with the interpretation of the study results, were excluded. Lactating women and those likely to become pregnant were excluded, as too were patients with hypersensitivity to the study medications.
The PK subgroup included patients randomized to lanreotide autogel who were attending either of two selected study sites (Peking Union Medical College Hospital (PUMCH), Beijing, China or West China Hospital, Sichuan University, Sichuan, China).
Study design and interventions
LANTERN was a phase 3, prospective, randomized, stratified, parallel-group, non-inferiority study comparing the efficacy and safety of lanreotide autogel 60, 90, or 120 mg with lanreotide 40 mg PR (ClinicalTrials.gov: NCT02493517; chinadrugtrials.org.cn: CTR20140698; Figure 1). The study was conducted between 29 October 2014 and 16 February 2017. As the treatments differed in method and frequency of administration, the study was conducted on an open-label basis. There were 32 weeks of study treatment (all patients) and an 8-week extension phase without study treatment for further assessment of PK in a subgroup of patients receiving lanreotide autogel. The study was conducted in 10 specialist centres in China, including eight endocrinology sites and two neurosurgery sites. Patients were enrolled by investigators and randomized, using a computer‑generated list (prepared by a sponsor independent statistician) to lanreotide autogel or lanreotide 40 mg PR in a 1:1 ratio, with stratification based on the presence or absence of previous pituitary surgery. Investigators obtained randomization codes through an interactive web response system.
Patients received lanreotide autogel 90 mg every 4 weeks (deep subcutaneous injection) up to Week 13, or lanreotide 40 mg PR every 10 days (intramuscular injection) up to Week 15. IGF-1 and mean GH levels were measured at Week 13 to assess each patient’s response and guide dose titration (from Week 17 for those receiving lanreotide autogel and Week 16 for those receiving lanreotide 40 mg PR; Figure 1). For up-titration of lanreotide autogel to 120 mg every 4 weeks or lanreotide 40 mg PR every 7 days, GH levels had to be >2.5 µg/L or IGF-1 levels >ULN; for down-titration of lanreotide autogel to 60 mg every 4 weeks or lanreotide 40 mg PR every 14 days, GH levels had to be ≤1.0 µg/L and IGF-1 levels normalized.
Treatment then remained unchanged until the end of the study. Patients in the PK subgroup discontinued lanreotide autogel during the PK extension phase, but could receive octreotide as rescue medication, if required.
Study visits and assessments
Study visits and assessments are detailed in Figure 1.
Hormone and tumor assessments
IGF-1 samples were assayed using Chemiluminescence (Siemens Healthcare GmbH, Germany) at screening, weeks 1, 5, 13, and at either week 28 (patients receiving lanreotide 40 mg PR every 14 days) or week 29 (lanreotide autogel, lanreotide 40 mg PR every 10 days and lanreotide 40 mg PR every 7 days), and at the end-of-study/early withdrawal visit (pre-dose under fasting conditions except week 1, which was taken after study treatment). GH levels were assayed using electrochemiluminescence (ECL) and the automated MODULAR ANALYTICS E 170 (both Roche, Basel, Switzerland) using standard calibration against recombinant GH (international reference preparation 98/574). Fasting mean GH levels, calculated from a 2-hour fasting GH cycle (five consecutive samples taken at 0, 30, 60, 90, and 120 minutes) were assessed at screening, week 13, week 29 (patients receiving lanreotide autogel only) and at the end-of-study/early withdrawal visit (pre-dose in all cases). Random GH levels were assessed at weeks 1 and 5, then at weeks 28 or 29 (as for IGF-1 levels) (pre-dose, except week 1). IGF-1 and GH levels were determined centrally from blood samples.
Tumor volumes (solid component) were measured centrally by two independent readers (using prespecified methods; Bioclinica, Newark, California, and Ipsen Pharma, Les Ulis, France) from MRI scans obtained at screening and at the end-of-study/early withdrawal visit. Readers were blind to sequence of scans and patients’ treatment allocation. The readers measured tumor volumes by drawing tumor contours on each MRI image where the adenoma was visible; the volume was then automatically calculated by Smart Study Direct (version 9) software (Bioclinica, Newark, California), taking contour areas and slice thickness into account. Solid and liquid (cyst-like) components of the adenoma were quantified separately. In case of discrepancies between readers, a third reader adjudicated. Acromegaly symptoms (headache, excessive perspiration, fatigue, soft‑tissue swelling, and arthralgia) were graded (absent, mild, moderate, severe) at screening, Week 13 and at the end-of-study/early withdrawal visit.
Glycaemia and HbA1c assessments
All clinical laboratory tests were performed by a central laboratory (LabCorp, Burlington, North Carolina). HbA1c was measured using high-performance liquid chromatography by Bio-Rad Variant II Turbo Hemoglobin assay system to measure HbA1c.
PK assessments
Lanreotide autogel – pre-dose serum samples were taken at weeks 1, 13, 17, and 29; sampling around 4 hours after treatment at weeks 13 and 17 and at the end of study (Week 33)/early withdrawal visit. For a subset of patients in the PK subgroup, additional samples were taken during the study and during the PK extension phase: after the first administration of 90 mg at Week 1 (1, 4, 6, 8, 12, 24, and 72 hours), Week 2 (168 hours), Week 3 (336 hours), Week 4 (504 hours) and prior to the next administration at Week 5 (672 hours); after the fourth (last) administration of the titrated dose at Week 29 (1, 4, 6, 8, 12, 24, and 72 hours), Week 30 (168 hours), Week 31 (336 hours), Week 32 (504 hours), and at Week 37 (1344 hours) and Week 41 (2016 hours).
Lanreotide 40 mg PR – pre-dose serum samples were taken at weeks 1, 2, 13, 16, and at the end-of-study/early withdrawal visit (all taken shortly before treatment) for all patients.
Safety parameters
Treatment-emergent adverse events (TEAEs) were monitored throughout the study. Vital signs were assessed, and physical examinations and clinical laboratory tests performed at screening, Week 13 and at the end‑of-study/early withdrawal visit. Gallbladder echography and electrocardiograms (ECG) were performed at screening, Week 13 (ECG only) and at the end-of-study/early withdrawal visit. Any clinically significant findings on the ECG, in the opinion of the investigator, were recorded as adverse events (AEs).
As recommended by regulatory guidelines, a multi-tiered approach was used to test for the presence of anti-drug (lanreotide) antibodies (ADA). Sera samples were assessed centrally at weeks 1 and 13, and at the end-of-study/early withdrawal visit using an electrochemiluminescence assay for the detection of binding ADAs. This assay used a bridging assay format, whereby labelled forms (with biotin and SulfoTAG) of lanreotide were used as tracers. Briefly, sera samples were incubated with biotin-lanreotide and SulfoTAG-lanreotide; after the incubation period, where binding equilibrium was reached, the mixture was transferred to a streptavidin-coated Meso Scale Discovery plate. Immune complexes composed of biotin-lanreotide, anti-lanreotide antibodies and SulfoTAG-lanreotide were captured by the streptavidin plate and measured by electrochemiluminescence. Positive samples identified in the screening electrochemiluminescence assay were submitted to a confirmatory electrochemiluminescence assay. These ADA positive samples were further analyzed using a titration assay to determine the titer value (reciprocal dilution at the highest dilution greater or equal to the screening cut point).
Endpoints
The primary endpoint was the mean change-from-baseline in age-adjusted IGF-1 level (expressed as standard deviation score [SDS]) at the end-of-study/early withdrawal visit. Secondary efficacy endpoints included proportions of patients achieving normalized IGF-1 levels, GH levels ≤2.5 µg/L, GH levels ≤1.0 µg/L, and normalized IGF-1 levels with 1.0 µg/L<GH levels ≤2.5 µg/L; changes in GH levels; proportions of patients with ≥20% reduction in tumor volume; changes in tumor volume; proportions of patients with at least one symptom of acromegaly compared with baseline; and safety. Analyses of efficacy endpoints by treatment regimen (ie, lanreotide autogel 60, 90 and 120 mg or lanreotide 40 mg PR 7, 10 and 14 days) was a defined secondary efficacy endpoint. However, as a result of the small numbers of patients receiving some regimens, it was not possible to interpret findings and these data are not considered within this manuscript.
PK endpoints included trough lanreotide concentrations (Ctrough i.e. observed serum concentration at the end of the dosing interval) prior to the fourth, fifth and eighth administrations and at the end-of-study treatment visit with lanreotide autogel, and prior to the second, tenth and twelfth administrations and at the end-of-study visit with lanreotide 40 mg PR. Following a similar approach as reported by Bronstein and colleagues, a non-compartmental PK analysis was performed for the lanreotide autogel PK subgroup to provide individual PK parameters over a 4‑week dosing interval after the first and last administration of study drug (i.e. steady state): maximum plasma concentration (Cmax), time to maximum plasma concentration (tmax), area under the concentration–time curve over a 4-week dosing interval (AUCtau), Ctrough and elimination t½ [19].
Additional parameters were estimated, comparing lanreotide PK after Week 1 and Week 29 after normalization to a dose of 90 mg: accumulation ratio for Ctrough (Rtrough) = Ctrough,Week 29/Ctrough,Week 1; accumulation ratio for Cmax (Rmax) = Cmax,Week 29/Cmax,Week 1; accumulation ratio for AUCtau (RAUC) = AUCtau, Week 29/AUCtau, Week 1.
Statistical analyses
Statistical analyses were performed using SAS® version 9.3 (SAS Institute Inc., Cary, NC, USA). Non-inferiority was declared if the upper limit of the two-sided 95% confidence intervals (CI) for the treatment difference in the primary endpoint (lanreotide autogel – lanreotide 40 mg PR) was less than the non-inferiority margin (i.e. 0.6 log[SDS] for least squares [LS] mean difference of log [base e] IGF-1 SDS values between treatment groups resulting from the generalized linear model [GLM]), and 50 patients per group were required for 81% power. Assuming that approximately 85% of the patients randomized were evaluated in the per protocol (PP) population, 59 patients per group were required to be randomized. Therefore to ensure at least 100 patients in the PP population, a total of 118 patients were needed for randomization (intention-to-treat [ITT] population).
The ITT population included all randomized and treated patients having ≥1 baseline and ≥1 post‑baseline assessment of the primary efficacy parameter. The PP population included all ITT patients for whom no major protocol deviations occurred with impact on efficacy assessment. The safety population comprised all randomized patients who received at least one dose of study drug. The primary efficacy endpoint was the mean change-from-baseline in age-adjusted IGF-1 values (expressed as log-transformed SDS values) at the end-of-study/early withdrawal visit in patients treated with lanreotide autogel and lanreotide 40 mg PR. For each patient, the respective IGF-1 SDS value was calculated based on the z‑score derivation: IGF-1 SDS = (IGF-1 – mean) / (standard deviation; SD), with mean and SD derived from the ULN and lower limit of normal (LLN) margins provided by the central laboratory for each age category (LLN = mean – 2 SD; ULN = mean + 2 SD). Secondary efficacy endpoints were analyzed using descriptive statistics and tabulated by treatment group for the ITT population only. For safety data, baseline values were defined as the last measurement of the specific safety variables collected before the first dose of study treatment. In general, descriptive statistics were used. All efficacy endpoints were analyzed at end-of-study/early withdrawal visit, corresponding to a last observation carried forward imputation approach for early withdrawal. No other imputations were performed for missing data. For safety endpoints, if a value required a retest (for clinical laboratory, vital signs, ECGs, gallbladder echography), the closest non-missing reliable value to the scheduled visit was used in the summary tables. A PK/pharmacodynamic analysis for lanreotide autogel, describing the relationship between serum lanreotide levels and GH and IGF-1 compared with GH levels, was performed where possible using NONMEM software (Version 7.3).
This manuscript adhered with CONSORT guidelines/methodology.