Fig. 2. The combination of radiotherapy and CD47 blockade leads to abscopal effects in preclinical mouse models of SCLC.
a, Mouse KP1 SCLC cells were engrafted into both flanks of B6129SF1 immunocompetent syngeneic mice and only right-side tumors were irradiated. b, Growth curves of KP1 SCLC allografts as in a with the indicated treatments (irradiated tumors on left, non-irradiated tumors on right). n = 1 experiment with n = 4 (RT) or n = 5 (control, anti-CD47 and RT + anti-CD47) mice. Irradiated tumors, ****P < 0.0001, **P = 0.0061; non-irradiated tumors, **P = 0.0012, **P = 0.0020. c, Mouse KP1 SCLC cells were engrafted into both flanks of B6129SF1 immunocompetent syngeneic mice. Right-side tumors received 20 Gy in five fractions. d, Growth curves of KP1 SCLC allografts with the indicated treatments in irradiated and non-irradiated control tumors. n = 1 experiment with n = 5 mice (two tumors per mouse). Irradiated tumors, **P = 0.0079; non-irradiated tumors, **P = 0.0079, **P = 0.0079. e, KP1 cells were both intravenously injected and engrafted into the right side of flank of B6129SF1 mice. The cells that were injected intravenously formed liver metastases. Only these liver metastases were irradiated. f, Representative image of liver sections stained with hematoxylin and eosin (H&E). Scale bar, 500 µm. n = 1 experiment with n = 5 mice. g, Growth curves of non-irradiated KP1 SCLC subcutaneous (subcut.) allografts. n = 1 experiment with n = 5 mice. ***P = 0.0003, ***P = 0.0003. h, Quantification of tumor-infiltrating macrophages (CD11b+F4/80+) identified by flow cytometry from subcutaneous non-irradiated tumors collected in e. n = 1 experiment with n = 3 (anti-CD47) or n = 4 (control, RT and RT + anti-CD47) tumors. *P = 0.0440, *P = 0.0251. Two-tailed Student’s t-tests following two-way ANOVA were performed in b (irradiated tumors, P < 0.0001; non-irradiated tumors, P = 0.0003), d (irradiated tumors, P < 0.0001; non-irradiated tumors, P < 0.0001) and g (P < 0.0001). Two-tailed Student’s t-tests following one-way ANOVA were performed in h (P = 0.016). Error bars represent s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.