CCL2 and breast cancer: In mouse breast cancer models, discontinuation of anti-CCL2 treatment led to accelerated lung metastasis and increased monocyte recruitment, resulting in the death of the mice.1034,1035 Moreover, as several neutralizing antibodies targeting CCL2 have entered clinical trials, none of these studies have reported a sufficient therapeutic effect by inhibiting the CCL2/CCR2 axis as monotherapy.1036–1038