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In vivo pilot experiment of NSG mice bearing MG-63 subcutaneous tumours treated intravenously with different concentrations of A5/158-vc-MMAE.

Antibodies and their dilutions

Although the 5-year survival rates for sarcoma patients have improved, the proportion of patients relapsing after first-line treatment remains high, and the survival of patients with metastatic disease is dismal. Moreover, the extensive molecular heterogeneity of the multiple different sarcoma subtypes poses a substantial challenge to developing more personalized treatment strategies. From the IHC staining of a large set of 625 human soft-tissue sarcomas, we demonstrate strong tumor cell staining of the Endo180 (MRC2) receptor in a high proportion of samples, findings echoed in gene-expression data sets showing a significantly increased expression in both soft-tissue and bone sarcomas compared with normal tissue. Endo180 is a constitutively recycling transmembrane receptor and therefore an ideal target for an antibody–drug conjugate (ADC). An anti-Endo180 monoclonal antibody conjugated to the antimitotic agent, MMAE via a cleavable linker, is rapidly internalized into target cells and trafficked to the lysosome for degradation, causing cell death specifically in Endo180-expressing sarcoma cell lines. In a sarcoma tumor xenograft model, the Endo180-vc-MMAE ADC, but not an isotype-vc-MMAE control or the unconjugated Endo180 antibody, drives on-target cytotoxicity resulting in tumor regression and a significant impairment of metastatic colonization of the lungs, liver and lymph nodes. These data, together with the lack of a phenotype in mice with an Mrc2 genetic deletion, provide preclinical proof-of-principle evidence for the future development of an Endo180-ADC as a therapeutic strategy in a broad range of sarcoma subtypes and, importantly, with potential impact both on the primary tumor and in metastatic disease.

A series of hemicyanine dyes was synthesized starting from the vinyl chloride-based cyanine dye IR-780. The dyes absorbed and emitted in the near-infrared region, while heavy atom (bromo and iodo) substitution promoted the generation of both singlet oxygen (1O2) as well as a range of other reactive oxygen-based species (ROS) upon irradiation at wavelengths greater than 610 nm. One hemicyanine dye displayed an outstanding singlet oxygen quantum efficiency (φΔ = 0.8) and was successfully applied in in vitro studies to mimic photodynamic therapy application.

Taking inspiration from the assembly of so-called peptoids (N-alkylglycine oligomers) we present a new synthetic methodology whereby N-heterocyclic carbene (NHC) based Pd ligands were assembled using a sub-monomer approach and loaded with Pd via solid-phase synthesis. This allowed the rapid generation a library of NHC–palladium catalysts that were readily functionalised to allow bioconjugation. These catalysts were able to rapidly activate a caged fluorophore and ‘switch-on’ an anticancer prodrug in 3D cell culture.