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(90)Y-edotreotide treatment improved symptoms associated with malignant carcinoid among subjects with no treatment alternatives. Treatment was well-tolerated and had an acceptable expected AE profile.

SummaryObjective To evaluate the efficacy, safety and tolerability of octreotide LAR ® (long-acting repeatable octreotide) in the primary therapy of acromegaly. Design and patients Ninety-eight previously untreated acromegalics were recruited into this prospective multicentre study. A total of 68 patients successfully completed 48 weeks of the study period, received 12 doses of octreotide LAR 10 -30 mg every 4 weeks, and constituted the population used for this analysis.Measurements and results A clinically relevant reduction (i.e. to ≤ 5 µ g/l) in mean GH (mGH) was recorded in 72% of patients after 24 weeks of treatment, and 42% reached a 'safe' GH value ( ≤ 2·5 µ g/l). At week 48, 16 more patients were considered partial GH responders (GH > 2·5 µ g/l and ≤ 5 µ g/l) and 44% had reached a GH level ≤ 2·5 µ g/l. IGF-1 levels normalized in 38% and 34% of patients after 24 and 48 weeks of treatment, respectively. At study completion, 10 patients (14·7%) who had not normalized their IGF-1 levels had achieved at least a 50% decrement in this marker. In eight microadenoma patients, tumour volume decreased from a mean baseline level of 298 ± 145 mm 3 to 139 ± 94 mm 3 after 24 weeks and to 99 ± 70 mm 3 after 48 weeks of therapy. In 60 patients with macroadenoma, the corresponding values were 3885 ± 5077 mm 3 at baseline and 2723 ± 3435 and 2406 ± 3207 mm 3 after 24 and 48 weeks, respectively. At weeks 24 and 48, a significant ( > 20%) tumour volume reduction was reported in 63% and 75% of patients, respectively. A reduction in the severity of symptoms of acromegaly was observed early in treatment and was maintained throughout the study period. Conclusion Octreotide LAR represents a viable alternative to surgery for primary treatment of acromegaly leading to a progressive regression of tumour volume, a sustained control of biochemical abnormalities and an adequate relief of symptoms of the disease.

The pharmacokinetics and dosimetry of (86)Y-DOTA(0)- d-Phe(1)-Tyr(3)-octreotide ((86)Y-SMT487) were evaluated in a phase I positron emission tomography (PET) study of 24 patients with somatostatin receptor-positive neuroendocrine tumours. The effect of amino acid (AA) co-infusion on renal and tumour uptake was assessed in a cross-over randomised setting. Five regimens were tested: no infusion, 4-h infusion of 120 g mixed AA (26.4 g l-lysine + l-arginine), 4 h l-lysine (50 g), 10 h 240 g mixed AA (52.8 g l-lysine + l-arginine) and 4 h Lys-Arg (25 g each). Comparisons were performed on an intra-patient basis. Infusions of AA started 0.5 h prior to injection of (86)Y-SMT487 and PET scans were obtained at 4, 24 and 48 h p.i. Absorbed doses to tissues were computed using the MIRD3 method. (86)Y-SMT487 displayed rapid plasma clearance and exclusive renal excretion; uptake was noted in kidneys, tumours, spleen and, to a lesser extent, liver. The 4-h mixed AA co-infusion significantly ( P<0.05) reduced (86)Y-SMT487 renal uptake by a mean of 21%. This protective effect was significant on the dosimetry data (3.3+/-1.3 vs 4.4+/-1.0 mGy/MBq; P<0.05) and was further enhanced upon prolonging the infusion to 10 h (2.1+/-0.4 vs 1.7+/-0.2 mGy/MBq; P<0.05). Infusion of Lys-Arg but not of l-lysine was more effective in reducing renal uptake than mixed AA. Infusion of AA did not result in reduced tumour uptake. The amount of (90)Y-SMT487 (maximum allowed dose: MAD) that would result in a 23-Gy cut-off dose to kidneys was calculated for each study: MAD was higher with mixed AA co-infusion by a mean of 46% (10-114%, P<0.05 vs no infusion). In comparison with 4 h mixed AA, the MAD was higher by a mean of 23% (9-37%; P<0.05) with prolonged infusion and by a mean of 16% (2-28%; P<0.05) with Lys-Arg. We conclude that infusion of large amounts of AA reduces renal exposure during peptide-based radiotherapy and allows higher absorbed doses to tumours. The prolongation of the infusion from 4 to 10 h further enhances the protective effect on the kidneys.