Interaction of Human Chorionic Gonadotropin (hCG) and Asialo-hCG with Recombinant Human Thyrotropin Receptor.

hCG is a putative thyroid stimulator. The present studies were undertaken to examine its interaction and that of its desialylated variant asialo-hCG with recombinant human TSH (hTSH) receptor (hTSHr). To this end, we transfected a human thyroid carcinoma cell line (HTC) lacking endogenous TSHr with the full-length cDNA of the hTSHr. Unlike the wild type, the transfected cells, termed HTC-TSHr cells, were able to bind bovine TSH (bTSH) with high affinity and increase cAMP production in response to bTSH stimulation. Of the hCG forms, intact hCG displayed a weak activity to inhibit [125I] bTSH binding to HTC-TSHr cells, with 100 mg/L (2.6 x 10(-6) mol/L) producing maximally a 20% inhibition, whereas asialo-hCG achieved half-maximum binding inhibition at a concentration of 8 mg/L (2.3 x 10(-7) mol/L). The inhibitory constant (Ki) of asialo-hCG for recombinant hTSHr was calculated from saturation experiments in the presence of variable doses of bTSH and a fixed concentration of asialo-hCG to be approximately 8 x 10(-8) mol/L. The interaction of asialo-hCG with TSHr was further assessed by studies of the direct binding of the radioactively labeled hormone to both HTC and HTC-TSHr cells. [125I]Asialo-hCG binding to HTC-TSHr cells was 4.7%, compared to 1.5% in the wild-type cells lacking TSHr and was displaceable by bTSH (0.1-100 IU/L), indicating specific binding of the tracer to TSHr. Functionally, hCG (up to 100 mg/L; 2.6 x 10(-6) mol/L) proved unable to evoke any significant cAMP response over basal values in HTC-TSHr cells, as did asialo-hCG. Asialo-hCG, but not hCG, inhibited bTSH-stimulated adenylate cyclase activity in the cells in a dose-dependent manner. In conclusion, the present data show that intact hCG binds only weakly to HTC-TSHr cells and produces no significant cAMP stimulation, which is at variance with data obtained in FRTL-5 and Chinese hamster ovary-TSHr cells, but in good accord with previous findings in human thyroid membranes. Asialo-hCG, on the other hand, strongly binds to recombinant TSHr and inhibits the cAMP response to bTSH in HTC-TSHr cells, indicating that the desialylated hCG variant directly interacts with the receptor and truly is an antagonist of the hTSHr

Efficacy and safety of once-monthly efpeglenatide in patients with type 2 diabetes: Results of a phase 2 placebo-controlled, 16-week randomized dose-finding study

Aims: To determine the optimal dose(s) of once-monthly administration of efpeglenatide, a long-acting glucagon-like peptide-1 receptor agonist (GLP-1RA), in patients with type 2 diabetes (T2D) inadequately controlled on metformin. Materials and methods: In this phase 2, randomized, placebo-controlled, double-blind trial (NCT02081118), patients were randomized 1:1:1:1 to subcutaneous efpeglenatide (8, 12 or 16 mg once monthly; n = 158) or placebo (n = 51). The 16-week treatment period included a 4-week titration phase with once-weekly efpeglenatide 4 mg, followed by one dose of efpeglenatide 8 mg once monthly and two doses of the assigned once-monthly dose. The primary endpoint was change in glycated haemoglobin (HbA1c) from baseline to week 17. Results: All efpeglenatide doses significantly reduced HbA1c versus placebo (P < 0.0001 for all). Overall, the least squares mean difference in HbA1c reductions between efpeglenatide and placebo was −7.7 mmol/mol (−0.71%; baseline to week 17). At week 17, a significantly greater proportion of efpeglenatide patients had an HbA1c level <53 mmol/mol (<7%) versus placebo (48.7% vs. 30.6%; P = 0.0320). Significant body weight loss occurred across all efpeglenatide doses (placebo-corrected reduction −2.0 kg [efpeglenatide overall]; P = 0.0003). The safety profile was consistent with GLP-1RAs, with gastrointestinal (GI) disorders being the most common treatment-emergent adverse events. Fluctuations in effects on glucose levels and rates of GI events occurred between peak and trough efpeglenatide concentrations. Conclusions: Efpeglenatide once monthly (following once-weekly titration) has significant benefits with regard to HbA1c and weight reduction versus placebo in patients with T2D. Further studies are needed to evaluate the long-term efficacy and safety of efpeglenatide once monthly