| 1. |
- Eriksson, Olof, et al.
(författare)
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Drug Occupancy Assessment at the Glucose-Dependent Insulinotropic Polypeptide Receptor by Positron Emission Tomography
- 2021
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Ingår i: Diabetes. - : AMER DIABETES ASSOC. - 0012-1797 .- 1939-327X. ; 70:4, s. 842-853
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Tidskriftsartikel (refereegranskat)abstract
- Targeting of the glucose-dependent insulinotropic polypeptide receptor (GIPR) is an emerging strategy in antidiabetic drug development. The aim of this study was to develop a positron emission tomography (PET) radioligand for the GIPR to enable the assessment of target distribution and drug target engagement in vivo. The GIPR-selective peptide S02-GIP was radiolabeled with Ga-68. The resulting PET tracer [Ga-68]S02-GIP-T4 was evaluated for affinity and specificity to human GIPR (huGIPR). The in vivo GIPR binding of [Ga-68]S02-GIP-T4 as well as the occupancy of a drug candidate with GIPR activity were assessed in nonhuman primates (NHPs) by PET. [Ga-68]S02-GIP-T4 bound with nanomolar affinity and high selectivity to huGIPR in overexpressing cells. In vivo, pancreatic binding in NHPs could be dose-dependently inhibited by coinjection of unlabeled S02-GIP-T4. Finally, subcutaneous pretreatment with a high dose of a drug candidate with GIPR activity led to a decreased pancreatic binding of [Ga-68]S02-GIP-T4, corresponding to a GIPR drug occupancy of almost 90%. [Ga-68]S02-GIP-T4 demonstrated a safe dosimetric profile, allowing for repeated studies in humans. In conclusion, [Ga-68]S02-GIP-T4 is a novel PET biomarker for safe, noninvasive, and quantitative assessment of GIPR target distribution and drug occupancy.
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| 2. |
- Espes, Daniel, 1985-, et al.
(författare)
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Longitudinal Assessment of 11C-5-Hydroxytryptophan Uptake in Pancreas After Debut of Type 1 Diabetes
- 2021
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 70:4, s. 966-975
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Tidskriftsartikel (refereegranskat)abstract
- The longitudinal alterations of the pancreatic β-cell and islet mass in the progression of type 1 diabetes (T1D) are still poorly understood. The objective of this study was to repeatedly assess the endocrine volume and the morphology of the pancreas for up to 24 months after T1D diagnosis (n = 16), by 11C-5-hydroxytryptophan (11C-5-HTP) positron emission tomography (PET) and MRI. Study participants were examined four times by PET/MRI: at recruitment and then after 6, 12, and 24 months. Clinical examinations and assessment of β-cell function by a mixed-meal tolerance test and fasting blood samples were performed in connection with the imaging examination. Pancreas volume has a tendency to decrease from 50.2 ± 10.3 mL at T1D debut to 42.2 ± 14.6 mL after 24 months (P < 0.098). Pancreas uptake of 11C-5-HTP (e.g., the volume of the endocrine pancreas) did not decrease from T1D diagnosis (0.23 ± 0.10 % of injected dose) to 24-month follow-up, 0.21 ± 0.14% of injected dose, and exhibited low interindividual changes. Pancreas perfusion was unchanged from diagnosis to 24-month follow-up. The pancreas uptake of 11C-5-HTP correlated with the long-term metabolic control as estimated by HbA1c (P < 0.05). Our findings argue against a major destruction of β-cell or islet mass in the 2-year period after diagnosis of T1D.
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