• Combination treatment with antibody-drug conjugates targeting Ror1 and Sortilin induces tumor regression in a mouse model of breast cancer
  • Miganoosh Simonian,1 Mozhan Haji Ghaffari,2 Niloufar Sadeghi,3 Babak Negahdari,4 Hodjattallah Rabbani,5,*
    1. Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
    2. Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
    3. Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
    4. Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
    5. Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran


  • Introduction: Triple negative breast cancer (TNBC) is highly invasive, metastatic and recurrent. Antibody drug conjugate (ADC) has received widespread attention in novel breast cancer therapy approaches. Among the tumor related antigens, Ror1 and Sortilin are among the most promising targets. The aim of this study is to produce immunoconjugates against these two molecules and measure their efficacy in vitro and in vivo separately and in combination with each other to overcome the stated limitations associated with cancer cells.
  • Methods: In this study, expression of Ror1 and Sortilin antigens in breast cancer cell lines, MDA-MB231 and 4T1 were evaluated using flow cytometry and immunocytochemistry. Monoclonal antibodies were conjugated to DM1 by Sulfo-SMCC linker and anti-tumor activity of anti-Ror1 and anti-Sortilin antibodies and their respective ADCs were assessed in vitro and in vivo.
  • Results: Flow cytometry revealed an increased expression level of Ror1 at 54.84 ± 2.63 (P <0.001) and 40.7 ± 2.54 (P <0.001) of MDA-MB231 and 4T1 cells, respectively. Immunocytochemical analysis confirms these findings. There is a substantial difference in the level of apoptosis caused by the Ror1-ADC compared to intact antibody. The highest rate of apoptosis was seen in the MDA-MB231 cells with a rate of nearly 50% for Ror1-ADC. Sortilin-ADC could induce 45.2% of apoptosis in 4T1 cells. Examination of in vivo activity revealed better tumor growth impediment in the two recipient groups, Ror1-ADC and Sortilin-ADC compared with BALB/c mice receiving the same amount of Ror1 and Sortilin antibodies (P <0.05). while antibody treatment showed no apparent effect on breast tumor growth, the mice survival rate increased compared to irrelevant-mAb group. In the case of the ADC combination treatment group, the results are remarkably indicative of success with a high percentage of tumor growth control.
  • Conclusion: Our study reveals the important role of Ror1 and Sortilin in the survival of breast cancer cells. Our findings also suggest that mAb-DM1 compounds have strong and selective antitumor activity in vitro and in vivo that augment their possible use as a Therapeutic agent in targeted cancer therapies, especially TNBC cancers with high heterogeneity that makes treatment choices more challenging.
  • Keywords: Triple negative breast cancer; Antibody-drug conjugates; Sortilin; Ror1