Pasireotide and Pegvisomant Combination Treatment in Acromegaly Resistant to Second-Line Therapies: A Longitudinal Study.

Abstract

The treatment of acromegaly resistant to first- and second-line therapies can be extremely challenging. We have described six patients who were successfully treated with a combination therapy of pasireotide and pegvisomant and compared them with a control group of patients resistant to conventional somatostatin analogs (SSAs), whose disease was controlled with other treatment, such as pasireotide (as monotherapy) or pegvisomant (as monotherapy or combined with conventional SSAs). In these six patients, acromegaly was controlled with combined pasireotide and pegvisomant treatment after failure of all other treatments. Compared with the 49 patients in the control group, these six patients had giant and invasive pituitary adenomas (at both the cavernous sinus and other structures). Although not statistically significant, higher growth hormone levels, more elevated Ki-67 expression, greater somatostatin receptor (SSTR) subtype 5 expression, and lower SSTR subtype 2 expression at the diagnosis of acromegaly were detected in patients receiving combination treatment with pasireotide and pegvisomant compared with the control group. Our data have reinforced the importance of personalized treatment of patients with acromegaly according to the clinical, biochemical, molecular, and morphological disease markers and suggest that combined treatment with pasireotide and pegvisomant can induce disease control in tumors with low SSTR2 expression, resistant to conventional SSAs (alone or combined with pegvisomant) and to new-generation SSAs alone (pasireotide).