Background: In the present study we investigated the efficacy and tolerabil
ity of i.m. octreotide acetate (octreotide LAR) in patients with metastatic
neuroendocrine tumors (NETs) previously treated and failed on i.m. lanreot
Patients and methods: Fifteen patients (8 females, 7 males, median age 67 y
ears, range 28-81 years) with metastatic NETs (8 endocrine pancreatic tumor
s, 7 midgut carcinoids) were enrolled in the study. All patients were in pr
ogressive disease (objective: 11 patients, symptomatic: 10 patients, bioche
mical: 11 patients) after treatment with slow release lanreotide, 30 mg eve
ry 14 days for a median time of 8 months (range 3-19 months). All patients
had measurable disease; 12 patients had elevated serum and/or urine markers
and 11 were symptomatic. Octreotide scintigraphy was positive in 13 of 15
patients. Octreotide LAR was administered as i.m. injection at the dose of
20 mg every four weeks until disease progression.
Results: An objective partial response (PR) was documented in one patient (
7%), no change (NC) in six (40%), and progressive disease (PD) in eight pat
ients (53%). The PR was observed in one patient with non-functioning endocr
ine pancreatic tumor with progressive liver and lymph node metastases after
16 months of i.m. lanreotide therapy. The median duration of disease stabi
lization was 7.5 months (range 6-12+ months). The overall biochemical respo
nse rate was 41%, including CRs (33%) and PRs (8%); biochemical responses w
ere observed in carcinoids as well as in endocrine pancreatic tumors; the m
edian duration of response was 5 months for CRs and 7.5 months for PRs. The
overall symptomatic response rate was 82%. The median duration of response
for diarrhoea, abdominal pain, or both was 6.5 months (range 3-12+ months)
. Improvement in performance status (PS) was obtained in 5 of 11 patients w
ith PS of 1 at study entry.
Median duration of octreotide LAR treatment was seven months (range 3-12+ m
onths). No serious adverse events were reported; mild side effects were rep
orted in 26% of patients.
Conclusions: Octreotide LAR 20 mg shows significant efficacy in terms of ob
jective response rate (PR + SD), biochemical and symptomatic control in pat
ients with metastatic NETs of the GEP system pretreated and progressing on
slow release lanreotide.