Relapsed refractory CLL paients randomized to two different doses (5x10 8 vs. 5x10 7)of CD19 targeted CAR T cells to find optimal dose.

Among enrolled patients, 4 pts received higher dose level (5 x 108 CTL019 cells) and 6 pts randomized to lower dose level (5 x 107CTL019 cells). No significant infusional toxicities noted.

Preliminary analysis does not suggest dose:response or dose:toxicity relationship. 50% of patient from higher dose cohort and 33% of lower dose cohort responded.

Cytokine release syndrom occured in 3/4 recipients of higher dose and 4/6 of recipients of lower dose CTL019 cells.

In this ongoing dose optimization study of CTL019 cells, 4 of first 10 pts treated have responded within 3 months.

With short follow-up, as yet no suggestion of dose:response or dose:toxicity relationships at dose ranges being studied.

These cells can undergo robust in vivo expansion and from other studies (ASH 2013) can persist for at least 3 yrs.

Trial confirms that CTL019 cells can induce potent responses for pts with advanced, relapsed and refractory CLL.