Optimizing Somatostatin Analog Therapy in Acromegaly

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.

Evaluation of Nurses' and Patients' Overall Satisfaction with New and Previous Formulations of Octreotide Long-acting Release (Sandostatin LAR®): A French Observational Study

INTRODUCTION

The first long-acting release (LAR) formulation of octreotide was marketed in France in the late 1990s. An injectable formulation of Sandostatin LAR^® (Novartis SAS) with a new diluent has been developed to facilitate its preparation and administration and to improve its use in practice.

METHODS

We conducted an observational, cross-sectional and multicenter study in France whose main outcome was to compare nurses' satisfaction with the preparation and administration of both previous and new formulations of octreotide LAR. Secondary outcomes included assessment of patient satisfaction (quality of life and pain felt during the injection) and product tolerance. Data were collected at two time points (one for the first formulation group and one for the second formulation group) through paper questionnaires administered to physicians, patients and nurses including a visual analog scale (VAS) from 0 (unsatisfied) to 10 (very satisfied).

RESULTS

Results showed that overall nurse satisfaction improved from 5.3 (95% CI 4.9-5.8) with the previous formulation to 7.5 (95% CI 7-7.9) with the new formulation (p < 0.0001). Regarding secondary outcomes, the simplicity of the injection increased (84% for the previous formulation and 94% for the new formulation) and the purge problem disappeared (36% for the previous formulation and 4% for the new formulation).

CONCLUSION

The improvement due to the new formulation of Sandostatin LAR^® was reported in terms of handling, ease of use and overall nurse satisfaction. The new formulation greatly reduced treatment administration problems associated with the previous formulation, while maintaining low injection site pain and an equivalent safety profile in both indications.

Agonist-biased trafficking of somatostatin receptor 2A in enteric neurons

Somatostatin (SST) 14 and SST 28 activate somatostatin 2A receptors (SSTR2A) on enteric neurons to control gut functions. SST analogs are treatments of neuroendocrine and bleeding disorders, cancer, and diarrhea, with gastrointestinal side effects of constipation, abdominal pain, and nausea. How endogenous agonists and drugs differentially regulate neuronal SSTR2A is unexplored. We evaluated SSTR2A trafficking in murine myenteric neurons and neuroendocrine AtT-20 cells by microscopy and determined whether agonist degradation by endosomal endothelin-converting enzyme 1 (ECE-1) controls SSTR2A trafficking and association with β-arrestins, key regulators of receptors. SST-14, SST-28, and peptide analogs (octreotide, lanreotide, and vapreotide) stimulated clathrin- and dynamin-mediated internalization of SSTR2A, which colocalized with ECE-1 in endosomes and the Golgi. After incubation with SST-14, SSTR2A recycled to the plasma membrane, which required active ECE-1 and an intact Golgi. SSTR2A activated by SST-28, octreotide, lanreotide, or vapreotide was retained within the Golgi and did not recycle. Although ECE-1 rapidly degraded SST-14, SST-28 was resistant to degradation, and ECE-1 did not degrade SST analogs. SST-14 and SST-28 induced transient interactions between SSTR2A and β-arrestins that were stabilized by an ECE-1 inhibitor. Octreotide induced sustained SSTR2A/β-arrestin interactions that were not regulated by ECE-1. Thus, when activated by SST-14, SSTR2A internalizes and recycles via the Golgi, which requires ECE-1 degradation of SST-14 and receptor dissociation from β-arrestins. After activation by ECE-1-resistant SST-28 and analogs, SSTR2A remains in endosomes because of sustained β-arrestin interactions. Therapeutic SST analogs are ECE-1-resistant and retain SSTR2A in endosomes, which may explain their long-lasting actions.

Preliminary data on biochemical remission of acromegaly after somatostatin analogs withdrawal

OBJECTIVE

It is still unknown whether prolonged treatment with somatostatin analogs (SSTa) may cause a long-lasting disease remission in GH-secreting adenomas after drug discontinuation. The aim of the present study was to investigate the evolution of GH/IGF-I secretion and tumor mass after SSTa withdrawal in patients affected by acromegaly.

PATIENTS AND DESIGN

A total of 27 patients with acromegaly (12 de novo and 15 previously operated) were treated with SSTa for a median period of 48 months and considered optimally controlled in hormonal and neuroradiological terms. None of them were previously irradiated.

METHODS

Basal GH, post-glucose GH nadir, IGF-I, clinical signs/symptoms, and metabolic parameters were evaluated after 12-16 weeks from drug withdrawal. Only patients who met the current criteria for disease remission remained in drug suspension being periodically re-evaluated for biochemical/clinical data and neuroradiological imaging.

RESULTS

After 12-16 weeks withdrawal, 15 of the 27 patients had disease relapse and restarted SSTa, while 12 were considered 'in disease remission' (44% of total). Glucose metabolism improved in both euglycemic and diabetic patients after short-term SSTa discontinuation. Only one of the ten patients who reached 24 weeks withdrawal showed biochemical disease recurrence. On the whole, five of the patients still in remission after 6 months have already prolonged the follow-up over 12 months (median: 24 months), without clinical and biochemical/neuroradiological evidence of disease recurrence.

CONCLUSIONS

These preliminary data indicate a successful withdrawal of SSTa at least in a subset of well-responsive patients with acromegaly and challenge the previously held concept that medical therapy is always a lifelong requirement.