CTLA4 and neoplasm: On the other hand, while both ixabepilone and paclitaxel were inactive in the CT-26 colon carcinoma model, enhanced efficacy was observed in combination with anti-mCTLA-4 mAb, suggesting that perhaps minimum induction of tumor cell death was necessary in this model to prime an immune response and potentiate the effect of CTLA-4 blockade.