Structure-activity relationships of 111In- and 99mTc-labeled quinolin-4-one peptidomimetics as ligands for the vitronectin receptor: potential tumor imaging agents.

The integrin receptor alpha(v)beta(3) is overexpressed on the endothelial cells of growing tumors and on some tumor cells themselves. Radiolabeled alpha(v)beta(3) antagonists have demonstrated potential application as tumor imaging agents and as radiotherapeutic agents. This report describes the total synthesis of eight new HYNIC and DOTA conjugates of receptor alpha(v)beta(3) antagonists belonging to the quinolin-4-one class of peptidomimetics, and their radiolabeling with (99m)Tc (for HYNIC) and (111)In (for DOTA). Tethering of the radionuclide-chelator complexes was achieved at two different sites on the quinolin-4-one molecule. All such derivatives maintained high affinity for receptor alpha(v)beta(3) and high selectivity versus receptors alpha(IIb)beta(3), alpha(v)beta(5), alpha(5)beta(1). Biodistribution of the radiolabeled compounds was evaluated in the c-neu Oncomouse mammary adenocarcinoma model. DOTA conjugate (111)In-TA138 presented the best biodistribution profile. Tumor uptake at 2 h postinjection was 9.39% of injected dose/g of tissue (%ID/g). Activity levels in selected organs was as follows: blood, 0.54% ID/g; liver, 1.94% ID/g; kidney, 2.33% ID/g; lung, 2.74% ID/g; bone, 1.56% ID/g. A complete biodistribution analysis of (111)In-TA138 and the other radiolabeled compounds of this study are presented and discussed. A scintigraphic imaging study with (111)In-TA138 showed a clear delineation of the tumors and rapid clearance of activity from nontarget tissues.

Design, synthesis, and evaluation of radiolabeled integrin alpha v beta 3 receptor antagonists for tumor imaging and radiotherapy.

The goal of this research is the development of tumor imaging and radiotherapeutic agents based on targeting of the integrin alpha(v)beta(3) (vitronectin receptor). Macrocyclic chelator DOTA has been conjugated to peptidomimetic vitronectin receptor antagonist SH066 to give TA138. TA138 and (89)Y-TA138 retain antagonist properties and high affinity for integrin alpha(v)beta(3) (IC(50) = 12 and 18 nM, respectively), and good selectivity versus integrin alpha(IIb)beta(3) (IC(50) > 10,000 nM). TA138 forms stable complexes with (111)In and (90)Y in > 95% RCP. (111)In-TA138 demonstrates high tumor uptake in the c-neu Oncomouse (Charles River Laboratories [Charles River, Canada]) mammary adenocarcinoma model (9.39% ID/g at 2 hours PI) and low background activity. Blood clearance is rapid and excretion is renal. Tumors are visible as early as 0.5 hours PI. Radiotherapy studies in the c-neu Oncomouse model demonstrated a slowing of tumor growth at a dose of 15 mCi/m(2), and a regression of tumors at a dose of 90 mCi/m(2).