Novartis’ chimeric antigen receptor (CAR) therapy CTL019 has caused a stir with fresh data showing that 27 of 30 patients with relapsed/refractory acute lymphoblastic leukaemia, or 90%, achieved complete remission.

The Swiss major and the University of Pennsylvania's Perelman School of Medicine have announced preliminary results from two trials which have been published in the New England Journal of Medicine of closely-watched CTL019. The therapy uses CAR technology to reprogramme a patient's own T cells to ‘hunt’ cancer cells that express specific proteins, called CD19. After they have been reprogrammed, the T cells (now called CTL019) are re-introduced into the patient's blood, where they proliferate and bind to the targeted cancer cells and destroy them.

Median follow-up was just over six months, with event-free survival of 67% and overall survival of 78%. ALL is the most common cancer diagnosed in children, representing 25% of cases among those younger than 15.

Lead investigator Stephan Grupp of Perelman said that this represents “the largest experience to date of CD19-CAR T cells and demonstrates the ability of this approach to achieve sustained complete responses in a patient population with few other treatment options”. He added that “we are especially hopeful for those patients who remain in remission for one-two years without further therapy”.

In terms of side effects, all patients who received CTL019 experienced cytokine release syndrome. However, of the 30 patients, 22 experienced mild to moderate CRS, while the eight with severe CRS were effectively treated with the IL-6 receptor antibody Roche’s Actemra (tocilizumab). Several patients experienced neurologic toxicities, which fully resolved without further intervention or apparent long-term implications.

Updated results on CTL019, which received breakthrough therapy designation from the US Food and Drug Administration in July, will be presented at the American Society of Hematology meeting in December.