monomethyl-auristatin-e and Kidney-Neoplasms

Topics: Acetazolamide; Animals; Antineoplastic Agents; Carbonic Anhydrase IX; Cell Line, Tumor; Drug Discovery; Humans; Immunoconjugates; Kidney Neoplasms; Mice, Nude; Molecular Structure; Molecular Targeted Therapy; Oligopeptides; Small Molecule Libraries; Tissue Distribution; Tubulin Modulators; Xenograft Model Antitumor Assays

Small molecule-drug conjugates (SMDCs) are increasingly being considered as an alternative to antibody-drug conjugates (ADCs) for the selective delivery of anticancer agents to the tumor site, sparing normal tissues. Carbonic anhydrase IX (CAIX) is a membrane-bound enzyme, which is over-expressed in the majority of renal cell carcinomas and which can be efficiently targeted in vivo, using charged derivatives of acetazolamide, a small heteroaromatic sulfonamide. Here, we show that SMDC products, obtained by the coupling of acetazolamide with monomethyl auristatin E (MMAE) using dipeptide linkers, display a potent anti-tumoral activity in mice bearing xenografted SKRC-52 renal cell carcinomas. A comparative evaluation of four dipeptides revealed that SMDCs featuring valine-citrulline and valine-alanine linkers exhibited greater serum stability and superior therapeutic activity, compared to the counterparts with valine-lysine or valine-arginine linkers. The most active products substantially inhibited tumor growth over a prolonged period of time, in a tumor model for which sunitinib and sorafenib do not display therapeutic activity. However, complete tumor eradication was not possible even after ten intravenous injection. Macroscopic near-infrared imaging procedures confirmed that ligands had not lost the ability to selectively localize at the tumor site at the end of therapy and that the neoplastic masses continued to express CAIX. The findings are of mechanistic and of therapeutic significance, since CAIX is a non-internalizing membrane-associated antigen, which can be considered for targeted drug delivery applications in kidney cancer patients.

Topics: Acetazolamide; Animals; Antineoplastic Agents; Carbonic Anhydrase Inhibitors; Carbonic Anhydrase IX; Carcinoma, Renal Cell; Cell Line, Tumor; Drug Delivery Systems; Female; Humans; Kidney; Kidney Neoplasms; Mice; Mice, Inbred BALB C; Mice, Nude; Oligopeptides

SLITRK6 is a member of the SLITRK family of neuronal transmembrane proteins that was discovered as a bladder tumor antigen using suppressive subtractive hybridization. Extensive immunohistochemistry showed SLITRK6 to be expressed in multiple epithelial tumors, including bladder, lung, and breast cancer as well as in glioblastoma. To explore the possibility of using SLITRK6 as a target for an antibody-drug conjugate (ADC), we generated a panel of fully human mAbs specific for SLITRK6. ADCs showed potent in vitro and in vivo cytotoxic activity after conjugation to Monomethyl Auristatin E or Monomethyl Auristatin F. The most potent ADC, ASG-15ME, was selected as the development candidate and given the product name AGS15E. ASG-15ME is currently in phase I clinical trials for the treatment of metastatic urothelial cancer. This is the first report that SLITRK6 is a novel antigen in bladder cancer and also the first report of the development of ASG-15ME for the treatment of metastatic bladder cancer. Mol Cancer Ther; 15(6); 1301-10. ©2016 AACR.

Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Discovery; Gene Expression Regulation, Neoplastic; Humans; Immunoconjugates; Kidney Neoplasms; Membrane Proteins; Mice; Oligopeptides; Up-Regulation; Urothelium; Xenograft Model Antitumor Assays

Metastatic renal cell carcinoma (RCC) is an aggressive disease refractory to most existing therapeutic modalities. Identifying new markers for disease progression and drug targets for RCC will benefit this unmet medical need. We report a subset of clear cell and papillary cell RCC aberrantly expressing the lymphocyte activation marker CD70, a member of the tumor necrosis factor superfamily. Importantly, CD70 expression was found to be maintained at the metastatic sites of RCC. Anti-CD70 antibody-drug conjugates (ADC) consisting of auristatin phenylalanine phenylenediamine (AFP) or monomethyl auristatin phenylalanine (MMAF), two novel derivatives of the anti-tubulin agent auristatin, mediated potent antigen-dependent cytotoxicity in CD70-expressing RCC cells. Cytotoxic activity of these anti-CD70 ADCs was associated with their internalization and subcellular trafficking through the endosomal-lysosomal pathway, disruption of cellular microtubule network, and G2-M phase cell cycle arrest. The efficiency of drug delivery using anti-CD70 as vehicle was illustrated by the much enhanced cytotoxicity of antibody-conjugated MMAF compared with free MMAF. Hence, ADCs targeted to CD70 can selectively recognize RCC, internalize, and reach the appropriate subcellular compartment(s) for drug release and tumor cell killing. In vitro cytotoxicity of these ADCs was confirmed in xenograft models using RCC cell lines. Our findings provide evidence that CD70 is an attractive target for antibody-based therapeutics against metastatic RCC and suggest that anti-CD70 ADCs can provide a new treatment approach for advanced RCC patients who currently have no chemotherapeutic options.

Topics: Animals; Antigens, CD; Antineoplastic Agents; Apoptosis; Carcinoma, Renal Cell; CD27 Ligand; Cell Cycle; Humans; Immunoconjugates; Immunohistochemistry; Kidney Neoplasms; Lymphocyte Activation; Membrane Proteins; Mice; Mice, Nude; Microtubules; Oligopeptides; Phenylalanine; RNA, Messenger; Tumor Necrosis Factors; Xenograft Model Antitumor Assays