# Safety, efficacy and determinants of response of allogeneic CD19-specific CAR-NK cells in CD19+ B cell tumors: a phase 1/2 trial

## TL;DR

This study shows that allogeneic CAR-NK cells are safe and effective for treating CD19+ B cell tumors, with response linked to specific cord blood features.

## Contribution

The study identifies cord blood unit characteristics that predict better outcomes in CAR-NK cell therapy for B cell malignancies.

## Key findings

- No major toxicities were observed in patients receiving CAR19/IL-15 NK cells.
- Patients with optimal cord blood units showed higher CAR-NK cell persistence and better responses.
- Mouse models confirmed superior antitumor activity of CAR-NK cells from optimal cord blood units.

## Abstract

There is a pressing need for allogeneic chimeric antigen receptor (CAR)-immune cell therapies that are safe, effective and affordable. We conducted a phase 1/2 trial of cord blood-derived natural killer (NK) cells expressing anti-CD19 chimeric antigen receptor and interleukin-15 (CAR19/IL-15) in 37 patients with CD19+ B cell malignancies. The primary objectives were safety and efficacy, defined as day 30 overall response (OR). Secondary objectives included day 100 response, progression-free survival, overall survival and CAR19/IL-15 NK cell persistence. No notable toxicities such as cytokine release syndrome, neurotoxicity or graft-versus-host disease were observed. The day 30 and day 100 OR rates were 48.6% for both. The 1-year overall survival and progression-free survival were 68% and 32%, respectively. Patients who achieved OR had higher levels and longer persistence of CAR-NK cells. Receiving CAR-NK cells from a cord blood unit (CBU) with nucleated red blood cells ≤ 8 × 107 and a collection-to-cryopreservation time ≤ 24 h was the most significant predictor for superior outcome. NK cells from these optimal CBUs were highly functional and enriched in effector-related genes. In contrast, NK cells from suboptimal CBUs had upregulation of inflammation, hypoxia and cellular stress programs. Finally, using multiple mouse models, we confirmed the superior antitumor activity of CAR/IL-15 NK cells from optimal CBUs in vivo. These findings uncover new features of CAR-NK cell biology and underscore the importance of donor selection for allogeneic cell therapies. ClinicalTrials.gov identifier: NCT03056339.

In the final report of a phase 1/2 trial evaluating allogeneic CD19-specific CAR-NK cells armored with IL-15 in patients with CD19+ hematologic malignancies, the therapy was shown to be safe and efficacious with distinct cord blood features associated with response.