111In-LLP2A-DOTA polyethylene glycol-targeting α4β1 integrin: Comparative pharmacokinetics for imaging and therapy of lymphoid malignancies

Sally J. Denardo, Ruiwu Liu, Huguette Albrecht, Arutselvan Natarajan, Julie Sutcliffe, Carolyn Anderson, Li Peng, Riccardo Ferdani, Simon R Cherry, Kit Lam

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

W-[[4-[[[(2-ethylphenyl)amino]carbonyl]amino]phenyl]acetyl]-N eS-6-[(2E)-1-oxo-3-(3-pyridinyl-2-propenyl)]-Llysyl-L-2- aminohexanedioyl-(1-amino-1-cyclohexane)carboxamide (LLP2A) is a highaffinity, high-specificity peptidomimetic ligand (inhibitory concentration of 50% = 2 pM) that binds the activated α4β1 integrin found on a variety of malignant lymphoid cell lines. To better determine whether this ligand holds promise for imaging and therapy in lymphoid malignancies, 6 LLP2A derivatives, as LLP2A-1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴- tetraacetic acid (LLP2A-DOTA) and LLP2A-DOTA-polyethylene glycol (LLP2A-DOTA-PEG), were designed, synthesized, and radiolabeled with 111In. Comparative pharmacokinetic studies in mice with Raji B-cell lymphoma xenografts were then complemented by small-animal PET of the lead molecular LLP2A format sing 64Cu-LLP2A-11-bis(carboxymethyl)-1,4,8, 11-tetraazabicyclo[6.6.2]hexadecane ( 64Cu-LLP2A-CB-TE2A). Methods: LLP2A-DOTA and LLP2A-CB-TE2A were prepared using solidphase synthesis; LLP2A-DOTA-PEG 2000, LLP2A-DOTA-PEG 5000, LLP2A-DOTA-PEG 10,000, (LLP2A-DOTA) 2PEG 10000, and (LLP2A-DOTA) 4PEG 10,000were prepared by PEGylation. 111In radiolabeling of DOTA and 64Cu radiolabeling of CB-TE2A conjugates yielded 370-1,850 and 3,700-7,400 kBq/μg (10-50 and 100-200 μCi/ μg), respectively. The pharmacokinetics of the six 111In radioconjugates were studied in vivo using biodistribution data (4 and 24 h) and whole-body autoradiography (24 h) in mice with Raji tumor xenografts. 64Cu-LLP2A-CB-TE2A was imaged (4 and 24 h) on a small-animal PET scanner in the same mouse model. Results: The highest tumor uptake in pharmacokinetic studies was obtained with LLP2A-DOTA and (LLP2A-DOTA) 4-PEG 10,000. For 111InLLP2A-DOTA (1 nM) at 4 and 24 h after injection, ratios of tumor to blood and tumor to nontumor (normal) organ (T/NT) were 8 to 35:1 for all organs or tissue except the spleen, marrow, and kidney, which were between 2:1 and 1:1. Tetravalent (LLP2A-DOTA) 4-PEG- 10,000 (1.1 nM) had tumor uptake similar to the univalent LLP2A-DOTA but higher liver, marrow, and kidney uptake. The excellent T/NT of LLP2A was also demonstrated by small-animal PET with 64Cu-LLP2A-CB-TE2A at both 4 and 24 h after injection; obvious spleen targeting was apparent, but little kidney or liver activity was observed. Conclusion: Of the conjugates investigated, the univalent, non-PEGylated ligand 111 In-LLP2A-DOTA exhibited the best T/NT ratios and showed the greatest potential for imaging f α4βuman lymphoma. Furthermore, this univalent non-PEGylated LLP2A format, as 64Cu-LLP2A-CB-TE2A, demonstrated excellent tumor targeting by small-animal PET and warrants urtherinvestigation asan agentforthestudyofα4β1 expression in human lymphoid malignancies. COPYRIGHT

Original languageEnglish (US)
Pages (from-to)625-634
Number of pages10
JournalJournal of Nuclear Medicine
Volume50
Issue number4
DOIs
StatePublished - Apr 1 2009

Keywords

  • α4β'
  • in
  • Cu
  • PEGylation
  • PET

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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