Fig. 5: Activation of long-term anti-tumor immunity by GN + OBP-702 in a neoadjuvant model using PAN02 subcutaneous tumors.
a Study protocol of a neoadjuvant model. C57BL/6 mice bearing PAN02 subcutaneous tumors were treated with GN (GEM 50 mg/kg, nab-PTX 5 mg/kg) intraperitoneally and/or OBP-702 (5 × 107 PFU) intratumorally three times in a week, and these tumors were surgically resected 7 days after the initial treatment. PAN02 cells were re-inoculated into the opposite side of the flank to the first tumor 28 days after tumor resection, and mice were monitored with no treatment and sacrificed 28 days after re-inoculation. b Tumor volume was monitored for 7 days until resection (left) (n = 6–7) and for 28 days after re-inoculation with no treatment (right). c Anti-CD8α antibody was added once on the day of the initial treatment in the protocol (a). Tumor volume was monitored the same as in (b) (n = 7). d, e PAN02 tumors harvested 28 days after re-inoculation were subjected to immunohistochemical staining for CD8. Representative images of immunohistochemical staining are shown in (d). Scale bar, 200 µm. The number of CD8+ TILs, which were evaluated in three different, randomly selected fields, were compared (n = 5-7) (e). f, g The spleens harvested 14 days after the initial treatment in the protocol (a) were subjected to flow cytometry for SLECs, MPECs, TEMps, and TCMps. Representative figures of flow cytometry are shown in (f), in which CD3+/CD8+ cells are analyzed in the upper figures, and CD3+/CD8+/CD127+ cells are analyzed in the lower figures. Populations of SLECs, MPECs, TEMps, and TCMps are compared (n = 5) (g). h, i The spleens harvested 35 days after the initial treatment in the protocol (a) were subjected to flow cytometry for TEMs and TCMs. Representative figures of flow cytometry are shown in (h), in which CD3+/CD8+ cells are analyzed. Populations of TEMs and TCMs are compared (n = 5) (i). *P < 0.05, **P < 0.005, ***P < 0.001. Con control, GN gemcitabine + nab-paclitaxel, 702 OBP-702, SLEC short-lived effector T cell, MPEC memory precursor effector cell, TEMp effector memory precursor cell, TCMp central memory precursor cell, TEM effector memory T cell, TCM central memory T cell.
