Source: Radiographics  |  Posted 5 years ago

By Maria Bishop

BOSTON, MA -- September 18, 2006 -- The relationship between pasireotide and growth hormone (GH) is characterized by a direct, concentration-related effect in active acromegalics, according to investigators presenting here at the American College of Clinical Pharmacology 35[^]th[] Annual Meeting (ACCP).

Acromegaly is a rare, serious hormonal disorder characterized by chronic hypersecretion of GH. In this study, 59 patients with active acromegaly due to a pituitary tumor were statistically analyzed for their responses to pasireotide, a novel somatostatin analogue with multiligand properties.

The study administered 4 weeks of octreotide (100 mcg sc 3 times daily) followed by a randomized, 3-period crossover phase of low, medium and high doses of pasireotide for 4 weeks (200 mcg sc twice daily, 400 mcg sc twice daily and 600 mcg sc twice daily, respectively).

Of the 59 patients analyzed, 23 (39%) were considered to be clinical responders, said lead investigator Lucy Lee, PharmD, clinical pharmacologist, Novartis Pharmaceuticals Corporation, East Hanover, New Jersey, in a presentation on September 17[^]th[]. The other 36 (61%) patients showed decreased levels of growth hormone and/or insulin-like growth-factor 1 (IGF-1).

In responders to this study, the median effective pasireotide concentration was 4.6 ng/mL, and the median growth hormone level was 1.46 ng/mL. Responders maintained a lower level of total IGF-1 and free IGF-1, although a dose-response relationship was not apparent there.

A median growth hormone suppression of at least 70% was achieved in both responders and nonresponders, noted Dr. Lee, a finding that suggests pharmacological activity in even the more resistant subjects within the study population.

The researchers concluded that a dose of at least 600 mcg twice daily will achieve a mean pasireotide exposure above the median effective concentration. Phase 3 studies will further evaluate clinical response in acromegalic patients starting at doses of 600 mcg twice daily and higher, they added.

[Presentation title: The Pharmacokinetic-Pharmacodynamic (PK-PD) Relationship of Pasireotide (SOM230), a Novel Somatostatin Analogue, in Patients With Acromegaly. Abstract 107]