Abstract
We have recently demonstrated CXCR4 overexpression in vestibular schwannomas (VS). This study investigated the feasibility of CXCR4-directed positron emission tomography/computed tomography (PET/CT) imaging of VS using the radiolabeled chemokine ligand [68Ga]Pentixafor.Methods: 4 patients with 6 primarily diagnosed or pre-treated/observed VS were enrolled. All subjects underwent [68Ga]Pentixafor PET/CT prior to surgical resection. Images were analyzed visually and semi-quantitatively for CXCR4 expression including calculation of tumor-to-background ratios (TBR). Immunohistochemistry served as standard of reference in three patients.Results: [68Ga]Pentixafor PET/CT was visually positive in all cases. SUVmean and SUVmax were 3.0 ± 0.3 and 3.8 ± 0.4 and TBRmean and TBRmax were 4.0 ± 1.4 and 5.0 ± 1.7, respectively. Histological analysis confirmed CXCR4 expression in tumors.Conclusion: Non-invasive imaging of CXCR4 expression using [68Ga]Pentixafor PET/CT of VS is feasible and could prove useful for in vivo assessment of CXCR4 expression.
Highlights
Vestibular schwannomas (VS) are benign nerve sheath tumors that arise from Schwann cells of the vestibulocochlear nerve [1, 2]
Surgery is the standard treatment in sporadic schwannoma, but not a long-lasting solution for neurofibromatosis type 2 (NF2)-related tumors since the disease is often associated with persistent cranial nerve deficits and high recurrence rates
Patient characteristics regarding tumor extension and clinical impairment are given in more detail in Table 1. [68Ga]-Pentixafor was administered on a compassionate use base in compliance with §37 of the Declaration of Helsinki and the German Medicinal Products Act, AMG §13 2b, and in accordance with the responsible regulatory body (Regierung von Oberfranken)
Summary
Vestibular schwannomas (VS) are benign nerve sheath tumors that arise from Schwann cells of the vestibulocochlear nerve [1, 2]. VS regularly cause hypoacusis, dizziness, and tinnitus. These tumors usually arise sporadically, in ∼5% of the cases they are associated with a rare (1:33,000) genetic disorder, neurofibromatosis type 2 (NF2). In NF2, they usually appear bilaterally, and compared to sporadic schwannomas, they grow faster and are much more adherent to the cranial nerves and CXCR4-PET/CT in Schwannomas the brainstem [5,6,7]. NF2-associated vestibular schwannomas are the more aggressive tumor entity. Surgery is the standard treatment in sporadic schwannoma, but not a long-lasting solution for NF2-related tumors since the disease is often associated with persistent cranial nerve deficits and high recurrence rates. Efficacious systemic or non-invasive therapies would be of value for these patients
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