Combination therapy with bevacizumab and CCR2 inhibitor for women with ovarian cancer: in vivo validation study

Purpose: Anti-angiogenic therapy with bevacizumab (BEV) plays a critical role in the treatment of ovarian cancer. However, despite the initial response, most tumors become resistant to BEV. We examined whether a synergistic effect between BEV and CCR2 inhibitors occurs in patient-derived xenografts (PDXs). Method: We established three consecutive PDXs (first high-grade serous, second clear cell, and third high-grade serous carcinoma) using immunodeficient NOD/Shi-SCID IL-2Rγ KO Jic mice. We randomly assigned mice (n=15, 8, and 8) to receive BEV (10 mg/kg) or a combination of BEV (10 mg/kg) and the CCR2 inhibitor BMS CCR2 22 (low-dose: 20 mg/kg or high-dose: 40 mg/kg) (BEV/CCR2i). Results: Low-dose BEV/CCR2i demonstrated significant growth suppression in the first BEV-resistant PDX and third BEV-sensitive PDX compared with BEV (30.4% after the second cycle and 15.5% after the first cycle, respectively), and treatment cessation did not attenuate this effect. Tissue clearing and immunohistochemistry with an anti-α-SMA antibody suggested that angiogenesis on the tumor surface was suppressed in BEV/CCR2i compared with BEV. Immunohistochemistry of human CD31 demonstrated that the microvessel density originating from human ovarian cancer was significantly lower in BEV/CCR2i than in BEV. Although the second PDX did not respond to low-dose BEV/CCR2i after the fifth cycle, two additional cycles of high-dose BEV/CCR2i demonstrated significant growth suppression compared with BEV (28.3%) by inhibiting the CCR2B-MAPK pathway. Conclusions: BEV/CCR2i showed a sustained and antitumor immunity-independent synergistic effect in human ovarian cancer. This benefit is more significant in serous carcinoma than in clear cell carcinoma.