(a) Antitumour activity was examined in an animal model with BXPC3 xenografts. NK105, PTX, or saline (as a control) was administered at a PTX equivalent dose of 50 mg/kg on days 0, 4, and 8. *P < 0.05 (PTX vs. NK105), ***P < 0.001 (saline vs. NK105). Bar = SD. (b)(c) Imaging of PTX within the tumour was performed after PTX (b) or NK105 (c) administration at a dose of 100 mg/kg. The upper, middle, and lower columns display the optical images, reference substance (an arbitrary signal of m/z 824.6), and PTX (specific signal of m/z 892.3 [M + K]+), respectively. Bar, 1 mm. (d)(e) LC-MS analysis of the PTX concentration in the tumours treated by PTX (d) or NK105 (e). Tissue sections serial to those shown in (b) and (c).