Lipophilicity Determines Routes of Uptake and Clearance, and Toxicity of an Alpha-Particle-Emitting Peptide Receptor Radiotherapy.

Lipophilicity is explored in the biodistribution (BD), pharmacokinetics (PK), radiation dosimetry (RD), and toxicity of an internally administered targeted alpha-particle therapy (TAT) under development for the treatment of metastatic melanoma. The TAT conjugate is comprised of the chelator DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate), conjugated to melanocortin receptor 1 specific peptidic ligand (MC1RL) using a linker moiety and chelation of the Ac radiometal. A set of conjugates were prepared with a range of lipophilicities (log values) by varying the chemical properties of the linker.

Biodistribution and Multicompartment Pharmacokinetic Analysis of a Targeted α Particle Therapy.

Targeted α particle therapy (TAT) is ideal for treating disease while minimizing damage to surrounding nontargeted tissues due to short path length and high linear energy transfer (LET). We developed a TAT for metastatic uveal melanoma, targeting the melanocortin-1 receptor (MC1R), which is expressed in 94% of uveal melanomas. Two versions of the therapy are being investigated: Ac-DOTA-Ahx-MC1RL (Ac-Ahx) and Ac-DOTA-di-d-Glu-MC1RL (Ac-di-d-Glu).

Melanocortin 1 Receptor-Targeted α-Particle Therapy for Metastatic Uveal Melanoma.

New effective therapies are greatly needed for metastatic uveal melanoma, which has a very poor prognosis with a median survival of less than 1 y. The melanocortin 1 receptor (MC1R) is expressed in 94% of uveal melanoma metastases, and a MC1R-specific ligand (MC1RL) with high affinity and selectivity for MC1R was previously developed. The Ac-DOTA-MC1RL conjugate was synthesized in high radiochemical yield and purity and was tested in vitro for biostability and for MC1R-specific cytotoxicity in uveal melanoma cells, and the lanthanum-DOTA-MC1RL analog was tested for binding affinity.

(S)-(Z)-Methyl 2-[2,3-bis-(benzyl-oxy-carbon-yl)guanidino]-4-methyl-penta-no-ate.

The title mol-ecule, C(24)H(29)N(3)O(6), has a nearly planar ten-atom C(3)N(3)O(4) core, on account of both N-H groups forming six-membered-ring intra-molecular hydrogen bonds to carbamate carbonyl O atoms. The absolute configuration was determined from resonant scattering of light atoms in Mo Kα radiation, agreeing with the configuration of starting materials.