GH and IGF-I levels and tumor shrinkage in response to first generation somatostatin receptor ligands in acromegaly: a comparative study between two reference centers for pituitary diseases in Brazil

Biomarkers of response to treatment in acromegaly

INTRODUCTION

Medical treatment of acromegaly is based in a `trial and error` approach. First-generation somatostatin receptor ligands (fg-SRL) are prescribed as first-line medical therapy to the vast majority of patients, despite lack of disease control in approximately 60% of patients. However, other drugs used in acromegaly treatment are available (cabergoline, pasireotide and pegvisomant).

AREAS COVERED

In this article, we review and discuss the biomarkers of response to medical treatment in acromegaly.

EXPERT OPINION

Biomarkers for fg-SRL that can already be applied in clinical practice are: gender, age, pretreatment GH and IGF-I levels, cytokeratin granulation pattern, and the expression of somatostatin receptor type 2. Using biomarkers of response could guide treatment towards precision medicine with greater efficacy and lower costs.

ACROBAT Edge: Safety and efficacy of switching injected SRLs to oral paltusotine in patients with acromegaly

CONTEXT

Paltusotine is a once-daily, oral, non-peptide small-molecule somatostatin receptor type 2 (SST2) agonist in clinical development for treatment of acromegaly.

OBJECTIVE

To evaluate change in IGF-I levels in patients switched from octreotide LAR or lanreotide depot monotherapy to paltusotine.

DESIGN

Phase 2, open-label, prospective, multicenter, multinational, non-randomized, single-arm exploratory study in which dosage up-titrations were performed in a double-blinded manner.

SETTING

26 global sites.

PARTICIPANTS

Patients with acromegaly switched to paltusotine from injected SRL-based therapy.

INTERVENTIONS

Patients received 13-week treatment with once-daily oral paltusotine (10-40 mg/day).

MAIN OUTCOME MEASURES

Primary endpoint was change from baseline to week 13 in IGF-I for patients who switched from long-acting octreotide or lanreotide monotherapy to paltusotine (Group 1). All patients underwent a 4-week paltusotine washout at end of treatment period (weeks 13-17). IGF-I, GH, patient reported outcome, and safety data were collected.

RESULTS

Forty-seven patients enrolled. In Group 1 (n = 25), IGF-I and GH showed no significant change between SRL baseline and end of paltusotine treatment at week 13 (median change in IGF-I = -0.03×upper limit of normal [ULN], P = 0.6285; GH = -0.05 ng/mL, P = 0.6285). IGF-I and GH rose significantly in the 4 weeks after withdrawing paltusotine (median change in IGF-I = 0.55×ULN, P < 0.0001 [median increase 39%]; GH = 0.72 ng/mL, P < 0.0001 [109.1% increase]). No patients discontinued due to adverse events; no treatment-related serious adverse events were reported.

CONCLUSIONS

These results suggest once daily, oral paltusotine is effective in maintaining IGF-I values in patients with acromegaly who switched from injected SRLs. Paltusotine was well tolerated with a safety profile consistent with other SRLs.