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. 2021 Dec 30;119(1):e2112491119. doi: 10.1073/pnas.2112491119

Fig. 4.

Fig. 4.

Combined LM008–HER2Ab NSCs and tucatinib increase survival in mice with HER2+ breast cancer cells growing in the brain. (A) Schematic model showing the dual inhibition of HER2 receptors in tumor cells. LM008–HER2Ab NSCs (green) and tucatinib (blue) target the phosphorylation and dimerization of HER2 receptors, inhibiting downstream growth and signal-transduction pathways. (B) Schematic representation of the experimental design. Firefly luciferase–positive BT474-Br cells were implanted directly in the brain via intracranial injection in immunodeficient (nu/nu) mice. Mice were randomly divided into five groups, and then, 7 and 14 d after implanting BT474-Br cells, two groups of mice received LM008 control cells ± tucatinib, another two groups received LM008–HER2Ab cells ± tucatinib, and one last group received placebo (PBS) and tucatinib as the therapeutic regimen. Tucatinib was given at 20 mg/kg through oral gavage for 21 consecutive days. End-point survival was then evaluated. (C) Quantitation of firefly luciferase BLI signal intensity (log10 p/s/cm2/sr) in the brain of mice from the indicated groups 1 mo after receiving BT474-Br cells intracranial. (D) Kaplan–Meier graph showing percent of survival in mice implanted with BT474-Br in the brain and treated with LM008 vector control (median survival 55 d), LM008 vector control + tucatinib (59 d), PBS + tucatinib (62 d), LM008–HER2Ab (92.5 d), and LM008–HER2Ab + tucatinib (114 d). (E) Representative histopathological and immunofluorescence pictures of brain sections harvested from mice treated systemically with LM008 vector control or LM008–HER2Ab NSCs in HER2+ multiple brain metastasis models. Note the presence of NSCs (GFP-positive staining shown in green) embedded within the tumor mass (HER2 positive, shown in red). Nuclear staining (DAPI) is shown in blue. Statistical analysis was performed using one-way ANOVA with post hoc Tukey’s test (C), and log-rank test was applied to compare mice survival (D, n = 8 per group). ****P < 0.0001, ***P < 0.001, **P < 0.01, and *P < 0.05.