A chimeric antigen receptor (CAR) T-cell “cocktail” targeting both CD19 and CD22 could improve outcomes for patients with refractory or relapsed B-cell malignancies, according to investigators.
This dual approach, which appeared safe and effective, may be able to overcome antigen escape relapse, reported Na Wang, MD, of Huazhong University of Science and Technology in China, and colleagues.
The investigators tested this method in an open-label, single-arm pilot study involving 89 patients with refractory/relapsed B cell malignancies. Of these, 51 patients had B-cell acute lymphoblastic leukemia (B-ALL), while the remaining 38 had non-Hodgkin lymphoma (NHL). All patients had dual expression of CD19 and CD22 on malignant B cells, good performance status, and “essentially” normal organ function, the investigators reported in Blood.
Following lymphodepletion, patients were infused with CAR19 and CAR22 T cells, then evaluated for responses with imaging or bone marrow aspiration on a monthly basis for 6 months, then every 3 months thereafter.
After 30 days, most patients with ALL (96%) achieved a minimal residual disease-negative complete response or complete response with incomplete count recovery. After a median follow-up of 16.7 months, almost half of these responders relapsed (49%), median progression-free survival was 13.6 months, and overall survival was 31 months.
With a minimum follow-up of 3 months, half of the patients with NHL (50%) achieved complete responses, with the caveat that two patients who died of septic shock and severe cytokine release syndrome were excluded from this efficacy analysis. After a median follow-up of 14.4 months, in the NHL group, median progression-free survival was 9.9 months and overall survival was 18 months.
Across disease types, almost all patients (95.5%) experienced cytokine release syndrome, with more than three-quarters (77.6%) categorized as grade 1 or 2. CAR T cell-related encephalopathy syndrome (CRES) occurred in 13.5% of patients; most were low grade, apart from one case that was grade 4. In total, 12 patients died due to adverse events.
“The severe [adverse events] were mostly cytopenias and the most frequent fatal [adverse event] was lung infection, which was attributable in part to the high disease burden and heavy pretreatment of the enrolled patients,” the investigators wrote. “Nearly all the high-grade CRS and CRES were reversible and occurred in similar incidences as previously reported. Thus, the sequential infusion of CAR19/22 T-cell “cocktail” was an efficient and well-tolerated approach to circumvent antigen loss of CD19 or CD22.”
The investigators reported having no conflicts of interest.
SOURCE: Wang N et al. 2019 Oct 29. doi: 10.1182/blood.2019000017.