Anti-CEA Pretargeted Immuno-PET Shows Higher Sensitivity Than DOPA PET/CT in Detecting Relapsing Metastatic Medullary Thyroid Carcinoma: Post Hoc Analysis of the iPET-MTC Study

Caroline Bodet-Milin; Alain Faivre-Chauvet; Thomas Carlier; Catherine Ansquer; Aurore Rauscher; Eric Frampas; Frederique Toulgoat; Damien Masson; Mickael Bourgeois; Evelyne Cerato; Vincent Rohmer; Olivier Couturier; Delphine Drui; David M. Goldenberg; Robert M. Sharkey; Jacques Barbet; Francoise Kraeber-Bodere

doi:10.2967/jnumed.120.252791

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FIGURE 1.
Immuno-PET/CT with anti-CEA BsmAb and ⁶⁸Ga-IMP288 peptide showing pathological lesions with heterogeneous SUV_max ranging from 3.0 to 20.1. Maximum-intensity-projection (MIP) image (A) showed several pathological lesions. On the fusion axial images, arrows located mediastinal nodes (B), subcutaneous lesions (C), and bone metastasis (D).
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FIGURE 2.
(A) Immuno-PET images with anti-CEA BsmAb and ⁶⁸Ga-IMP288 showing temporoparietal uptake in brain. CT of the PET/CT was negative. (B) PET/CT with ¹⁸F-DOPA PET/CT was negative. (C) Brain MRI (guided by immuno-PET) confirmed pathologic temporoparietal lesion (arrow).
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FIGURE 3.
(A) Immuno-PET/CT with anti-CEA BsmAb and ⁶⁸Ga-IMP288 maximum-intensity-projection (MIP) showing multiple pathologic lesions confirmed to be cervical and mediastinal nodes on the fusion axial images (arrows). (B) Pathological nodes were confirmed on contrast-enhanced CT (arrows) but not visualized by MIP or fusion axial ¹⁸F-DOPA PET/CT images (C). (D) Metastatic MTC involvement was confirmed by histologic analysis (hematoxylin/eosin/saffron staining, ×12.5 and ×200).
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FIGURE 4.
(A) Immuno-PET/CT with anti-CEA BsmAb and ⁶⁸Ga-IMP288 axial PET, CT, and fusion images showing multiple liver lesions (arrows), whereas ¹⁸F-DOPA PET was negative (B). (C) MRI-confirmed lesion.

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TABLE 1
Scheme of Cohorts
Cohort Patients (n) TF2 dose (nmol) Delay (h) ⁶⁸Ga-IMP288 dose and activity (nmol) MBq TF2/IMP288 molar dose ratio
I 3 120 24 6 150 20
II 3 + 9^{^*} 120 30 6 150 20
III 3 + 1^{^†} 120 42 6 150 20
IV 3 120 30 3 150 40
V 3 60 30 3 150 20
↵* Three patients in optimization phase of study and 9 in validation phase.
↵^† Patient 8 did not receive full hapten dose and was excluded and replaced for optimization phase study but was reintegrated for sensitivity study.

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TABLE 2

Patient Characteristics

Characteristic	Data
Total patients	22
Age (y)	62 (28–75)
Sex
Male	15
Female	7
Time from diagnosis (y)	5.5 (0.5–31)
Calcitonin concentration (pg/mL)	488 (154–39,000)
CEA concentration (ng/mL)	18 (3–1,443)
Location of disease
Lymph node	19
Lung	8
Liver	13
Bone	13
Other	4

Qualitative data are number; continuous data are median and range.

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TABLE 3

Sensitivity of Immuno-PET, ¹⁸F-DOPA PET/CT, and Conventional Imaging

Location	Immuno-PET	¹⁸F-DOPA PET/CT	CT	Liver MRI	Bone marrow MRI
Nodes	87/89 (98%)	64/89 (72%)	73/89 (82)%	NA	NA
Lung	4/14 (29%)	2/14 (14%)	14/14 (100%)	NA	NA
Liver	45/46 (98%)	30/46 (65%)	39/46 (87%)	41/46 (89%)	NA
Bone marrow	34/37 (92%)	25/37 (68%)	NA	NA	33/37 (89%)
Other	4/4 (100%)	3/4 (75%)	4/4 (100%)	NA	NA
Global	174/190 (92%)	124/190 (65%)	130/153 (85%)	NA	NA