Search

Objectives: To compare clinical characteristics, imaging findings and treatment requirements of patients with immune checkpoint inhibitor-mediated polymyalgia rheumatica (ICI-PMR) and primary PMR., Methods: This single centre, retrospective cohort study compared ICI-PMR in patients with cancer (n = 15) to patients with primary PMR (n = 37). A comparison was made between clinical symptoms, laboratory markers, ultrasonography,18F-FDG-PET/CT findings and treatment requirements related to PMR., Results: Patients with ICI-PMR less frequently fulfilled the EULAR/ACR classification criteria for PMR (66.7%) than patients with primary PMR (97.3%). Morning stiffness, weight loss and elevation of the ESR were less frequently seen in patients with ICI-PMR. No differences were observed regarding the presence of inflammatory lesions on ultrasound of the shoulders and hips between the two groups. The Leuven and the Leuven/Groningen 18F-FDG-PET/CT scores were significantly lower in the ICI-PMR group. Finally, the ICI-PMR group could be managed with less glucocorticoids than the primary PMR group., Conclusion: Our findings indicate that ICI-PMR may have a milder course with less inflammation than primary PMR on 18F-FDG-PET/CT. ICI-mediated PMR patients can be managed with a relatively low glucocorticoid dose. Our study underscores that ICI-PMR should be regarded as PMR-like syndrome., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

The mesothelin (MSLN)-targeted 227 Th conjugate is a novel α-therapy developed to treat MSLN-overexpressing cancers. We radiolabeled the same antibody-chelator conjugate with 89 Zr to evaluate whether PET imaging with 89 Zr-MSLN matches 227 Th-MSLN tumor uptake, biodistribution, and antitumor activity. Methods: Serial PET imaging with protein doses of 4, 20, or 40 μg of 89 Zr-MSLN and 89 Zr-control was performed up to 168 h after tracer injection in human tumor-bearing nude mice with high (HT29-MSLN) and low (BxPc3) MSLN expression. 89 Zr-MSLN and 227 Th-MSLN ex vivo tumor uptake and biodistribution were compared at 6 time points in HT29-MSLN and in medium-MSLN-expressing (OVCAR-3) tumor-bearing mice. 89 Zr-MSLN PET imaging was performed before 227 Th-MSLN treatment in HT29-MSLN and BxPc3 tumor-bearing mice. Results: 89 Zr-MSLN PET imaging showed an SUV mean of 2.2 ± 0.5 in HT29-MSLN tumors. Ex vivo tumor uptake was 10.6% ± 2.4% injected dose per gram at 168 h. 89 Zr-MSLN tumor uptake was higher than uptake of 89 Zr-control ( P = 0.0043). 89 Zr-MSLN and 227 Th-MSLN showed comparable tumor uptake and biodistribution in OVCAR-3 and HT29-MSLN tumor-bearing mice. Pretreatment SUV mean was 2.2 ± 0.2 in HT29-MSLN tumors, which decreased in volume on 227 Th-MSLN treatment. BxPc3 tumors showed an SUV mean of 1.2 ± 0.3 and remained similar in size after 227 Th-MSLN treatment. Conclusion: 89 Zr-MSLN PET imaging reflected MSLN expression and matched 227 Th-MSLN tumor uptake and biodistribution. Our data support the clinical exploration of 89 Zr-MSLN PET imaging together with 227 Th-MSLN therapy, both using the same antibody-chelator conjugate., (© 2022 by the Society of Nuclear Medicine and Molecular Imaging.)