Research Papers:

Therapeutic potential of nimotuzumab PEGylated-maytansine antibody drug conjugates against EGFR positive xenograft

Siddesh V. Hartimath, Ayman El-Sayed, Amal Makhlouf, Wendy Bernhard, Carolina Gonzalez, Wayne Hill, Angel Casaco Parada, Kris Barreto, Clarence Ronald Geyer and Humphrey Fonge _

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Oncotarget. 2019; 10:1031-1044. https://doi.org/10.18632/oncotarget.26613

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Siddesh V. Hartimath1,2, Ayman El-Sayed3, Amal Makhlouf1,2,4, Wendy Bernhard3, Carolina Gonzalez3, Wayne Hill3, Angel Casaco Parada5, Kris Barreto3, Clarence Ronald Geyer3 and Humphrey Fonge1,2,6

1Department of Medical Imaging, College of Medicine, University of Saskatchewan, Saskatoon SK, S7N 0W8, Canada

2Saskatchewan Centre for Cyclotron Sciences (SCCS), the Fedoruk Centre, Saskatoon SK, S7N 5C4, Canada

3Department of Pathology and Laboratory Medicine, College of Medicine, University of Saskatchewan, Saskatoon SK, S7N 5E5, Canada

4Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University, Kasr El-Aini, 12411, Cairo, Egypt

5Centre for Molecular Immunology, Havana, 11600, Cuba

6Department of Medical Imaging, Royal University Hospital Saskatoon, Saskatoon SK, S7N 0W8, Canada

Correspondence to:

Humphrey Fonge, email: [email protected]

Clarence Ronald Geyer, email: [email protected]

Keywords: epidermal growth factor receptor I; antibody drug conjugates; near infrared imaging; PEGylated maytansine; colorectal cancer

Received: September 07, 2018     Accepted: December 20, 2018     Published: February 01, 2019


Nimotuzumab is a humanized anti-epidermal growth factor receptor I (EGFR) monoclonal antibody. We have developed antibody drug conjugates (ADCs) with nimotuzumab conjugated to PEGylated-maytansine (PEG6-DM1). We generated conjugates with low (nimotuzumab-PEG6-DM1-Low: DAR = 3.5) and high (nimotuzumab-PEG6-DM1-High: DAR = 7.3) drug to antibody ratios (DAR). Quality control was performed using UV spectrophotometry, size exclusion HPLC, bioanalyzer, biolayer interferometry (BLI), and flow cytometry in EGFR-positive DLD-1, MDA-MB-468 (high density EGFR), and HT-29 (very low EGFR density) cells. Control antibody drug conjugates were developed using a human anti-maltose binding protein (MBP) antibody. BLI showed that the binding of nimotuzumab-PEG6-DM1-Low and nimotuzumab-PEG6-DM1-High was slightly but significantly affected by conjugation of the drug (nimotuzumab KD 0.89 ± 0.02 nM < nimotuzumab-PEG6-DM1-Low KD 1.94 ± 0.02 nM < nimotuzumab-PEG6-DM1-High KD 3.75 ± 0.03 nM). In vitro cytotoxicity was determined following incubation of cells with the immunoconjugates and IC50 values were determined. Nimotuzumab-PEG6-DM1-Low and nimotuzumab-PEG6-DM1-High were used to treat EGFR positive KRAS mutant DLD-1 colorectal cancer xenograft. DLD-1 cells were transduced with a red fluorescent protein (iRFP702) to allow the use of near infrared imaging (NIR) for tumor response monitoring. In vitro potency correlated with the number of drugs on antibody, with nimotuzumab-PEG6-DM1-High showing higher activity than nimotuzumab-PEG6-DM1-Low. Three doses (15 mg/kg) of the ADCs prolonged the survival of DLD-1-iRFP-702 tumor bearing mice as monitored by NIR. Nimotuzumab-PEG6-DM1-Low resulted in 4/6 complete cure while nimotuzumab-PEG6-DM1-High resulted in 2/5 complete cure. The novel ADCs were very effective in a colorectal cancer model in vivo.

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