Cetuximab PET delineated changes in cellular distribution of EGFR upon dasatinib treatment in triple negative breast cancer

Abstract

Background: At least 50% of triple negative breast cancer (TNBC) overexpress the epidermal growth factor receptor, EGFR, which paved the way for clinical trials investigating its blockade. Outcomes remained dismal stemming from mechanisms of resistance particularly the nuclear cycling of EGFR, which is enhanced by Src activation. Attenuation of Src reversed nuclear translocation, restoring EGFR to the cell surface. Herein, we hypothesize that changes in cellular distribution of EGFR upon Src inhibition with dasatinib can be annotated through the EGFR immunopositron emission tomography (immunoPET) radiotracer, [ 89 Zr]Zr-cetuximab. Methods: Nuclear and non-nuclear EGFR levels of dasatinib-treated vs. untreated MDA-MB-231 and MDA-MB-468 cells were analyzed via immunoblots. Both treated and untreated cells were exposed to [ 89 Zr]Zr-cetuximab to assess binding at 4°C and 37°C. EGFR-positive MDA-MB-231, MDA-MB-468, and a patient-derived xenograft were treated with dasatinib or vehicle followed by cetuximab PET imaging to compare EGFR levels. After imaging, the treated mice were separated into two groups: one cohort continued with dasatinib with the addition of cetuximab while the other cohort received dasatinib alone. Correlations between the radiotracer uptake vs. changes in tumor growth and EGFR expression from immunoblots were analyzed.Results: Treated cells displayed higher binding of [ 89 Zr]Zr-cetuximab to the cell membrane at 4°C and with greater internalized activity at 37°C vs. untreated cells. In all tumor models, higher accumulation of the radiotracer in dasatinib-treated groups was observed compared to untreated tumors. Treated tumors displayed significantly decreased pSrc (Y416) with retained total Src levels compared to control. In MDA-MB-468 and PDX tumors, the analysis of cetuximab PET vs. changes in tumor volume showed an inverse relationship where high tracer uptake in the tumor demonstrated minimal tumor volume progression. Furthermore, combined cetuximab and dasatinib treatment showed better tumor regression compared to control and dasatinib-only-treated groups. No benefit was achieved in MDA-MB-231 xenografts with the addition of cetuximab, likely due to its KRAS-mutated status.Conclusions: Cetuximab PET can monitor effects of dasatinib on EGFR cellular distribution and potentially inform treatment response in wild-type KRAS TNBC.

A Novel Bispecific Antibody Targeting EGFR and VEGFR2 Is Effective against Triple Negative Breast Cancer via Multiple Mechanisms of Action

“…Resistance to cetuximab therapy has been extensively studied in colorectal cancers, which shows that amplification of MET or HER2, deletion of PTEN, activation of KRAS, PIK3 CA and other oncogenes could cause persistent activation of growth signaling pathways in cancer cells, thus anti-EGFR mAbs therapy remains ineffective for such tumors [ 31 ]. The anti-EGFR/VEGFR2 BsAb described here demonstrates anti-tumor activity in TNBC cells including MDA-MB-231 cells which harbor KRAS mutation [ 32 ]. Our data show that anti-EGFR/VEGFR2 BsAb function similarly or better than cetuximab in blocking ligand-mediated phosphorylation/activation of EGFR signaling and its downstream molecules ERK and Akt in TNBC cells.…”

Potentiating Therapeutic Effects of Epidermal Growth Factor Receptor Inhibition in Triple-Negative Breast Cancer

“…Dasatinib is an orally available TKI of ABL1, SRC family kinases, KIT, and PDGFRα/β, and has been approved for the treatment of chronic myeloid leukemia (CML) and Philadelphia-chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) ( Table 4 ) [ 502 , 503 ]. Treatment with dasatinib alone reduced p-EGFR (Y845) and p-SRC (Y416), with a concordant reduction in nuclear EGFR and SRC and induction of radio-labeled cetuximab binding to the cell surface in TNBC cell lines such as MDA-MB-231 and MDA-MB-468 cells [ 440 ]. In an MDA-MB-468 xenograft model, the cetuximab and dasatinib combination further reduced the tumor volume compared with dasatinib alone, while no significant change was observed in an MDA-MB-231 xenograft model with this combination treatment [ 440 ].…”

“…Treatment with dasatinib alone reduced p-EGFR (Y845) and p-SRC (Y416), with a concordant reduction in nuclear EGFR and SRC and induction of radio-labeled cetuximab binding to the cell surface in TNBC cell lines such as MDA-MB-231 and MDA-MB-468 cells [ 440 ]. In an MDA-MB-468 xenograft model, the cetuximab and dasatinib combination further reduced the tumor volume compared with dasatinib alone, while no significant change was observed in an MDA-MB-231 xenograft model with this combination treatment [ 440 ]. Although the noted difference in these cell lines was a KRAS mutation (MDA-MB-468, wild-type vs. MDA-MB-231, mutated), further study is needed to determine the contributions of KRAS mutations to the differential effects of this combination.…”

Noninvasive Evaluation of EGFR Expression of Digestive Tumors Using 99mTc-MAG3-Cet-F(ab′)2-Based SPECT/CT Imaging

“…Therefore, noninvasive evaluation of the EGFR expression is particularly important. Cetuximab, an EGFR inhibitor widely used in clinical practice, is suitable for noninvasive evaluation of the EGFR expression [ 20 , 21 ].…”