We observed that the addition of anti-IgM stimulation to the co-culture system provided the greater sensitivity to TAK-659 (TAK-659 LD50 for CLL cells in suspension: 38.14 μM [95%CI 27.47–52.96] vs. TAK-659 LD50 for CLL cells in co-culture and anti-IgM: 16.91 μM [95%CI 10.61–26.93], P = 0.006) (Figure 3B). Here, CD40LG is linked to B-cell chronic lymphocytic leukemia.