Charlene Audette

Publications of Charlene Audette

• Synthesis and evaluation of hydrophilic linkers for antibody-maytansinoid conjugates.

  Authors: Robert Y Zhao, Sharon D Wilhelm, Charlene Audette, Gregory Jones, Barbara A Leece, Alexandru C Lazar, Victor S Goldmacher, Rajeeva Singh, Yelena Kovtun, Wayne C Widdison, John M Lambert, Ravi V J Chari

  Journal of medicinal chemistry. 05/2011; 54(10):3606-23.

  The synthesis and biological evaluation of hydrophilic heterobifunctional cross-linkers for conjugation of antibodies with highly cytotoxic agents are described. These linkers contain either aThe synthesis and biological evaluation of hydrophilic heterobifunctional cross-linkers for conjugation of antibodies with highly cytotoxic agents are described. These linkers contain either a negatively charged sulfonate group or a hydrophilic, noncharged PEG group in addition to an amine-reactive N-hydroxysuccinimide (NHS) ester and sulfhydryl reactive termini. These hydrophilic linkers enable conjugation of hydrophobic organic molecule drugs, such as a maytansinoid, at a higher drug/antibody ratio (DAR) than hydrophobic SPDB and SMCC linkers used earlier without triggering aggregation or loss of affinity of the resulting conjugate. Antibody-maytansinoid conjugates (AMCs) bearing these sulfonate- or PEG-containing hydrophilic linkers were, depending on the nature of the targeted cells, equally to more cytotoxic to antigen-positive cells and equally to less cytotoxic to antigen-negative cells than conjugates made with SPDB or SMCC linkers and thus typically displayed a wider selectivity window, particularly against multidrug resistant (MDR) cancer cell lines in vitro and tumor xenograft models in vivo.

• Maytansinoid-antibody conjugates induce mitotic arrest by suppressing microtubule dynamic instability.

  Authors: Emin Oroudjev, Manu Lopus, Leslie Wilson, Charlene Audette, Carmela Provenzano, Hans Erickson, Yelena Kovtun, Ravi Chari, Mary Ann Jordan

  Molecular cancer therapeutics. 10/2010; 9(10):2700-13.

  Maytansine and its analogues (maytansinoids) are potent microtubule-targeted compounds that inhibit proliferation of cells at mitosis. Antibody-maytansinoid conjugates consisting of maytansinoidsMaytansine and its analogues (maytansinoids) are potent microtubule-targeted compounds that inhibit proliferation of cells at mitosis. Antibody-maytansinoid conjugates consisting of maytansinoids (DM1 and DM4) attached to tumor-specific antibodies have shown promising clinical results. To determine the mechanism by which the antibody-DM1 conjugates inhibit cell proliferation, we examined the effects of the cleavable anti-EpCAM-SPP-DM1 and uncleavable anti-EpCAM-SMCC-DM1 conjugates on MCF7 human breast tumor cells. We also examined the effects of the free maytansinoids, maytansine and S-methyl DM1 (a version of DM1 that is stable in cell culture medium), for comparison. Both the conjugates and free maytansinoids potently inhibited MCF7 cell proliferation at nanomolar and subnanomolar concentrations, respectively, by arresting the cells in mitotic prometaphase/metaphase. Arrest occurred in concert with the internalization and intracellular processing of both conjugates under conditions that induced abnormal spindle organization and suppressed microtubule dynamic instability. Microtubule depolymerization occurred only at significantly higher drug concentrations. The results indicate that free maytansinoids, antibody-maytansinoid conjugates, and their metabolites exert their potent antimitotic effects through a common mechanism involving suppression of microtubule dynamic instability.

• Tumor Delivery and In Vivo Processing of Disulfide-Linked and Thioether-Linked Antibody-Maytansinoid Conjugates.

  Authors: Hans K Erickson, Wayne C Widdison, Michele F Mayo, Kathleen Whiteman, Charlene Audette, Sharon D Wilhelm, Rajeeva Singh

  Bioconjugate chemistry. 11/2009;

  Antibody-drug conjugates (ADCs) are designed to eradicate cancer cells that express the target antigen on their cell surface. A key component of an ADC is the linker that covalently connects theAntibody-drug conjugates (ADCs) are designed to eradicate cancer cells that express the target antigen on their cell surface. A key component of an ADC is the linker that covalently connects the cytotoxic agent to the antibody. Several antibody-maytansinoid conjugates prepared with disulfide-based linkers such as those targeting the CanAg antigen have been shown to display more activity in preclinical mouse xenograft models than corresponding conjugates prepared with uncleavable thioether-based linkers. To investigate how the linker influences delivery and activation of antibody-maytansinoid conjugates, we isolated and characterized the [(3)H]maytansinoids from CanAg-positive tumor tissues following a single intravenous administration of 300 mug/kg (based on maytansinoid dose) of anti-CanAg antibody (huC242)-(3)H-maytansinoid conjugates prepared with cleavable disulfide linkers and an uncleavable thioether linker. We identified three target-dependent tumor metabolites of the disulfide-linked huC242-SPDB-DM4, namely, lysine-N(epsilon)-SPDB-DM4, DM4, and S-methyl-DM4. We found similar metabolites for the less hindered disulfide-linked huC242-SPP-DM1 conjugate with the exception that no S-methyl-DM1 was detected. The sole metabolite of the uncleavable thioether-linked huC242-SMCC-DM1 was lysine-N(epsilon)-SMCC-DM1. The AUC for the metabolites of huC242-SMCC-DM1 at the tumor over 7 d was about 2-fold greater than the corresponding AUC for the metabolites of the disulfide-linked conjugates. The lipophilic metabolites of the disulfide-linked conjugates were found to be nearly 1000 times more cytotoxic than the more hydrophilic lysine-N(epsilon)-linker-maytansinoids in cell-based viability assays when added extracellularly. The cell killing properties associated with the lipophilic metabolites of the disulfide-linked conjugates (DM4 and S-methyl-DM4, and DM1) provide an explanation for the superior in vivo efficacy that is often observed with antibody-maytansinoid conjugates prepared with disulfide-based linkers in xenograft mouse models.

• Pharmacokinetics and biodistribution of the antitumor immunoconjugate, cantuzumab mertansine (huC242-DM1), and its two components in mice.

  Authors: Hongsheng Xie, Charlene Audette, Mary Hoffee, John M Lambert, Walter A Blättler

  The Journal of pharmacology and experimental therapeutics. 04/2004; 308(3):1073-82.

  The humanized monoclonal antibody maytansinoid conjugate, cantuzumab mertansine (huC242-DM1) that contains on average three to four linked drug molecules per antibody molecule was evaluated in CD-1The humanized monoclonal antibody maytansinoid conjugate, cantuzumab mertansine (huC242-DM1) that contains on average three to four linked drug molecules per antibody molecule was evaluated in CD-1 mice for its pharmacokinetic behavior and tissue distribution, and the results were compared with those of the free antibody huC242. The pharmacokinetics in blood were similar for (125)I-labeled conjugate and antibody with terminal half-lives of 154 and 156 h, respectively. Pharmacokinetic analysis using an enzyme-linked immunosorbent assay (ELISA) method, which measures intact conjugate in plasma samples revealed a faster clearance for the conjugate corresponding to a half-life of 42.2 h. This faster clearance is explained as the result of clearance from circulation and concomitant clearance of drug from circulating conjugate through linker cleavage. An antibody-specific ELISA allowed the determination of the clearance rate of the antibody component from circulation. The drug clearance rate from circulating conjugate was then calculated as the difference between the clearance of the conjugate and the clearance of the antibody component and found to be about three times that of the antibody component. The above results were confirmed with a conjugate, huC242-[(3)H]DM1, where the linked DM1 drugs carried a stable tritium label. Tissue distribution studies with (125)I-labeled conjugate and antibody showed antibody-like behavior for the conjugate; the antibody of the conjugate did not distribute or bind significantly to any solid tissue.

• Cantuzumab mertansine, a maytansinoid immunoconjugate directed to the CanAg antigen: a phase I, pharmacokinetic, and biologic correlative study.

  Authors: Anthony W Tolcher, Leonel Ochoa, Lisa A Hammond, Amita Patnaik, Tam Edwards, Chris Takimoto, Lon Smith, Johann de Bono, Garry Schwartz, Theresa Mays, Zdenka L Jonak, Randall Johnson, Mark DeWitte, Helen Martino, Charlene Audette, Kate Maes, Ravi V J Chari, John M Lambert, Eric K Rowinsky

  Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 02/2003; 21(2):211-22.

  PURPOSE: To determine the maximum tolerated dose and pharmacokinetics of cantuzumab mertansine, an immunoconjugate of the potent maytansine derivative (DM1) and the humanized monoclonal antibodyPURPOSE: To determine the maximum tolerated dose and pharmacokinetics of cantuzumab mertansine, an immunoconjugate of the potent maytansine derivative (DM1) and the humanized monoclonal antibody (huC242) directed to CanAg, intravenously (i.v.) once every 3 weeks and to seek evidence of antitumor activity. PATIENTS AND METHODS: Patients with CanAg-expressing solid malignancies were treated with escalating doses of cantuzumab mertansine administered i.v. every 3 weeks. The pharmacokinetic parameters of cantuzumab mertansine, the presence of plasma-shed CanAg, and the development of both human antihuman and human anti-DM1 conjugate antibodies also were characterized. RESULTS: Thirty-seven patients received 110 courses of cantuzumab mertansine at doses ranging from 22 to 295 mg/m2. Acute, transient, and reversible elevations of hepatic transaminases were the principal toxic effects. Nausea, vomiting, fatigue, and diarrhea were common but rarely severe at the highest dose levels. Dose, peak concentration, and area under the concentration-time curve correlated with the severity of transaminase elevation. The mean (+/- SD) clearance and terminal elimination half-life values for cantuzumab mertansine averaged 39.5 (+/-13.1) mL/h/m2 and 41.1 (+/-16.1) hours, respectively. Strong expression (3+) of CanAg was documented in 68% of patients. Two patients with chemotherapy-refractory colorectal carcinoma had minor regressions, and four patients had persistently stable disease for more than six courses. CONCLUSION: The recommended dose for cantuzumab mertansine is 235 mg/m2 i.v. every 3 weeks. The absence of severe hematologic toxic effects, preliminary evidence of cantuzumab mertansine tumor localization, and encouraging biologic activity in chemotherapy-refractory patients warrant further broad clinical development of this immunoconjugate in CanAg-expressing tumors.