# A long-acting interleukin-7, rhIL-7-hyFc, enhances CAR T cell expansion, persistence, and anti-tumor activity

## TL;DR

A long-acting version of interleukin-7 boosts the effectiveness of CAR T cell therapy by improving cell expansion and anti-tumor activity.

## Contribution

A long-acting IL-7 fusion protein (rhIL-7-hyFc) is introduced as a novel adjuvant to enhance CAR T cell therapy.

## Key findings

- rhIL-7-hyFc promotes proliferation and persistence of human and murine CAR T cells in mouse models.
- The treatment leads to long-term tumor-free survival in tested models.
- rhIL-7-hyFc is proposed as a clinic-ready adjuvant for improving CAR T cell activity.

## Abstract

Chimeric antigen receptor (CAR) T cell therapy is routinely used to treat patients with refractory hematologic malignancies. However, a significant proportion of patients experience suboptimal CAR T cell cytotoxicity and persistence that can permit tumor cell escape and disease relapse. Here we show that a prototype pro-lymphoid growth factor is able to enhance CAR T cell efficacy. We demonstrate that a long-acting form of recombinant human interleukin-7 (IL-7) fused with hybrid Fc (rhIL-7-hyFc) promotes proliferation, persistence and cytotoxicity of human CAR T cells in xenogeneic mouse models, and murine CAR T cells in syngeneic mouse models, resulting in long-term tumor-free survival. Thus, rhIL-7-hyFc represents a tunable clinic-ready adjuvant for improving suboptimal CAR T cell activity.

Chimeric antigen receptor T cells represent a breakthrough treatment in hematologic malignancies, but insufficient level of cytotoxicity and persistence of T cells might compromise success. Authors show here that a recombinant long acting form of interleukin-7 enhances proliferation, persistence and cytotoxicity of the engineered T cells, resulting in long term disease remission.