Nushmia Z. Khokhar, Denise Bonney, Paul Virgo, Saket Srivastava, Simon Thomas, Ram Jha, Jan Chu, Shaun Cordoba, Robert Chiesa, Persis Amrolia, Yiyun Zhang, Jeremy Hancock, Rachael Hough, Carlotta Peticone, Shimobi Onuoha, Kanchan Rao, Vania Baldan, Kevin Duffy, Paul Veys, Lucy Wheeler, Robert Wynn, William Day, Daniela Soriano Pignataro, Sara Ghorashian, Giovanna Lucchini, Koval Smith, Martin Pule, Liz Clark, Vijay G R Peddareddigari, Mathieu Ferrari, Sabine Domning, Ajay Vora, Frederick Arce Vargas, Muhammad Al-Hajj, Mei Mei Fung, and Farzin Farzaneh
Chimeric antigen receptor (CAR) T cells targeting CD19 or CD22 have shown remarkable activity in B cell acute lymphoblastic leukemia (B-ALL). The major cause of treatment failure is antigen downregulation or loss. Dual antigen targeting could potentially prevent this, but the clinical safety and efficacy of CAR T cells targeting both CD19 and CD22 remain unclear. We conducted a phase 1 trial in pediatric and young adult patients with relapsed or refractory B-ALL (n = 15) to test AUTO3, autologous transduced T cells expressing both anti-CD19 and anti-CD22 CARs (AMELIA trial, EUDRA CT 2016-004680-39). The primary endpoints were the incidence of grade 3–5 toxicity in the dose-limiting toxicity period and the frequency of dose-limiting toxicities. Secondary endpoints included the rate of morphological remission (complete response or complete response with incomplete bone marrow recovery) with minimal residual disease-negative response, as well as the frequency and severity of adverse events, expansion and persistence of AUTO3, duration of B cell aplasia, and overall and event-free survival. The study endpoints were met. AUTO3 showed a favorable safety profile, with no dose-limiting toxicities or cases of AUTO3-related severe cytokine release syndrome or neurotoxicity reported. At 1 month after treatment the remission rate (that is, complete response or complete response with incomplete bone marrow recovery) was 86% (13 of 15 patients). The 1 year overall and event-free survival rates were 60% and 32%, respectively. Relapses were probably due to limited long-term AUTO3 persistence. Strategies to improve CAR T cell persistence are needed to fully realize the potential of dual targeting CAR T cell therapy in B-ALL., Bicistronic CAR T cells targeting CD19 and CD22 exhibit clinical activity and low toxicity in pediatric and young adult patients with B cell acute lymphoblastic leukemia, with relapses associated with limited CAR T cell persistence.