The inextricable axis of targeted diagnostic imaging and therapy: An immunological natural history approach

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• 作者：Frederick O. Cope^a ; ^{fcope@navidea.com" class="auth_mail" title="E-mail the corresponding author} ; Bonnie Abbruzzese^a ; James Sanders^a ; Wendy Metz^a ; Kristyn Sturms^a ; David Ralph^a ; Michael Blue^a ; Jane Zhang^b ; Paige Bracci^b ; Wiam Bshara^c ; Spencer Behr^c ; Toby Maurer^c ; Kenneth Williams^d ; Joshua Walker^d ; Allison Beverly^e ; Brooke Blay^e ; Anirudh Damughatla^e ; Mark Larsen^e ; Courtney Mountain^e ; Erin Neylon^e ; Kaeli Parcel^e ; Kapil Raghuraman^e ; Kevin Ricks^e ; Lucas Rose^e ; Akhilesh Sivakumar^e ; Nicholas Streck^e ; Bryan Wang^e ; Christopher Wasco^e ; Amifred Williams^e ; Michael McGrath^b
• 关键词：Tilmanocept ; Macrophage ; CD206 ; Imaging ; Immunodiagnostic ; Immunotherapy
• 刊名：Nuclear Medicine and Biology
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：43
• 期：3
• 页码：215-225
• 全文大小：2552 K

文摘

In considering the challenges of approaches to clinical imaging, we are faced with choices that sometimes are impacted by rather dogmatic notions about what is a better or worse technology to achieve the most useful diagnostic image for the patient. For example, is PET or SPECT most useful in imaging any particular disease dissemination? The dictatorial approach would be to choose PET, all other matters being equal. But is such a totalitarian attitude toward imaging selection still valid? In the face of new receptor targeted SPECT agents one must consider the remarkable specificity and sensitivity of these agents. ^99mTc-Tilmanocept is one of the newest of these agents, now approved for guiding sentinel node biopsy (SLNB) in several solid tumors. Tilmanocept has a K_d of 3 × 10^− 11 M, and it specificity for the CD206 receptor is unlike any other agent to date. This coupled with a number of facts, that specific disease-associated macrophages express this receptor (100 to 150 thousand receptors), that the receptor has multiple binding sites for tilmanocept (> 2 sites per receptor) and that these receptors are recycled every 15 min to bind more tilmanocept (acting as intracellular “drug compilers” of tilmanocept into non-degraded vesicles), gives serious pause as to how we select our approaches to diagnostic imaging. Clinically, the size of SLNs varies greatly, some, anatomically, below the machine resolution of SPECT. Yet, with tilmanocept targeting, the SLNs are highly visible with macrophages stably accruing adequate ^99mTc-tilmanocept counting statistics, as high target-to-background ratios can compensate for spatial resolution blurring. Importantly, it may be targeted imaging agents per se, again such as tilmanocept, which may significantly shrink any perceived chasm between the imaging technologies and anchor the diagnostic considerations in the targeting and specificity of the agent rather than any lingering dogma about the hardware as the basis for imaging approaches. Beyond the elements of imaging applications of these agents is their evolution to therapeutic agents as well, and even in the neo-logical realm of theranostics. Characteristics of agents such as tilmanocept that exploit the natural history of diseases with remarkably high specificity are the expectations for the future of patient- and disease-centered diagnosis and therapy.