The effect of lanreotide on non-functioning pituitary macroadenoma size

In patients with clinically non-functioning pituitary macroadenomas (NFMA), the current therapeutic approach is to substitute any hormonal deficits, and to perform transsphenoidal surgery if
necessary. However, the remission rate after surgery is only 44% due to extensive growth on diagnosis. The available evidence concerning treatment and follow-up of NFMA is based exclusively on small, observational studies with a lack of well-designed randomized trials. It has been known for some decades that NFMA may express somatostatin receptors, as seen in surgical specimens and in vivo, using Indium-111 pentetreotide SPECT. We hypothesize that positive somatostatin receptor imaging with Gallium-68 DOTATATE PET/CT in pituitary NFMA predicts response to somatostatin analogue therapy and that this therapy will reduce the growth rate and/or tumor size in NFMA patients. We will therefore randomize 44 patients with positive NFMA uptake on Gallium-68 DOTATATE PET/CT to either lanreotide or placebo. Based on an expected PET-positivity rate of 66%, we expect to need to inlcude a maximum of 66 patients to be able to randomize 44 patients.

Lanreotide therapy can stabilize or reduce tumor size in Gallium-68 DOTATATE positive pituitary NFMA

baseline, 6 months,12 months and 18 months

AE's will be registered continuously

Gallium-68 DOTATATE PET/CT

> positive PET/CT: randomization:

Group 1 monthly subcutaneous injections of somatostatin analog (18 months)

Group 2 monthly subcutaneous injections of placebo (18 months)