Fc-fused IL-7 mobilizes long-term HSCs in a pro-B cell-dependent manner and synergizes with G-CSF and AMD3100

IL-7-primed bystander CD8 tumor-infiltrating lymphocytes optimize the antitumor efficacy of T cell engager immunotherapy

Bispecific T cell engagers (TCEs) show promising clinical efficacy in blood tumors, but their application to solid tumors remains challenging. Here, we show that Fc-fused IL-7 (rhIL-7-hyFc) changes the intratumoral CD8 T cell landscape, enhancing the efficacy of TCE immunotherapy. rhIL-7-hyFc induces a dramatic increase in CD8 tumor-infiltrating lymphocytes (TILs) in various solid tumors, but the majority of these cells are PD-1-negative tumor non-responsive bystander T cells. However, they are non-exhausted and central memory-phenotype CD8 T cells with high T cell receptor (TCR)-recall capacity that can be triggered by tumor antigen-specific TCEs to acquire tumoricidal activity. Single-cell transcriptome analysis reveals that rhIL-7-hyFc-induced bystander CD8 TILs transform into cycling transitional T cells by TCE redirection with decreased memory markers and increased cytotoxic molecules. Notably, TCE treatment has no major effect on tumor-reactive CD8 TILs. Our results suggest that rhIL-7-hyFc treatment promotes the antitumor efficacy of TCE immunotherapy by increasing TCE-sensitive bystander CD8 TILs in solid tumors.

Harnessing the Power of IL-7 to Boost T Cell Immunity in Experimental and Clinical Immunotherapies

The cytokine IL-7 plays critical and nonredundant roles in T cell immunity so that the abundance and availability of IL-7 act as key regulatory mechanisms in T cell immunity. Importantly, IL-7 is not produced by T cells themselves but primarily by non-lymphoid lineage stromal cells and epithelial cells that are limited in their numbers. Thus, T cells depend on cell extrinsic IL-7, and the amount of in vivo IL-7 is considered a major factor in maximizing and maintaining the number of T cells in peripheral tissues. Moreover, IL-7 provides metabolic cues and promotes the survival of both naïve and memory T cells. Thus, IL-7 is also essential for the functional fitness of T cells. In this regard, there has been an extensive effort trying to increase the protein abundance of IL-7 in vivo, with the aim to augment T cell immunity and harness T cell functions in anti-tumor responses. Such approaches started under experimental animal models, but they recently culminated into clinical studies, with striking effects in re-establishing T cell immunity in immunocompromised patients, as well as boosting anti-tumor effects. Depending on the design, glycosylation, and the structure of recombinantly engineered IL-7 proteins and their mimetics, recombinant IL-7 molecules have shown dramatic differences in their stability, efficacy, cellular effects, and overall immune functions. The current review is aimed to summarize the past and present efforts in the field that led to clinical trials, and to highlight the therapeutical significance of IL-7 biology as a master regulator of T cell immunity.

IL-7 and IL-7R in health and disease: An update through COVID times

The role of IL-7 and IL-7R for normal lymphoid development and an adequately functioning immune system has been recognized for long, with severe immune deficiency and lymphoid leukemia as extreme examples of the consequences of deregulation of the IL-7-IL-7R axis. In this review, we provide an update (focusing on the past couple of years) on IL-7 and IL-7R in health and disease. We highlight the findings on IL-7/IL-7R signaling mechanisms and the, sometimes controversial, impact of IL-7 and its receptor on leukocyte biology, COVID-19, acute lymphoblastic leukemia, and different solid tumors, as well as their relevance as therapeutic tools or targets.

Long-acting recombinant human interleukin-7, NT-I7, increases cytotoxic CD8+ T cells and enhances survival in mouse glioma models

PURPOSE

Patients with glioblastoma (GBM) are treated with radiation therapy (RT) and temozolomide (TMZ). These treatments may cause prolonged systemic lymphopenia, which itself is associated with poor outcomes. NT-I7 is a long-acting IL-7 that expands CD4 and CD8 T cell numbers in humans and mice. We tested whether NT-I7 prevents systemic lymphopenia and improves survival in mouse models of GBM.

EXPERIMENTAL DESIGN

C57BL/6 mice bearing intracranial tumors (GL261 or CT2A) were treated with RT (1.8 Gy/day x 5 days), TMZ (33 mg/kg/day x 5 days), and/or NT-I7 (10 mg/kg on the final day of RT). We followed the mice for survival while serially analyzing levels of circulating T lymphocytes. We assessed regulatory T cells (Treg) and cytotoxic T lymphocytes in the tumor microenvironment, cervical lymph nodes, spleen, and thymus; and hematopoietic stem and progenitor cells (HSPCs) in the bone marrow.

RESULTS

GBM tumor-bearing mice treated with RT+NT-I7 increased T lymphocytes in the lymph nodes, thymus, and spleen, enhanced IFNγ production, and decreased T_reg cells in the tumor which was associated with a significant increase in survival. NT-I7 also enhanced central memory and effector memory CD8 T cells in lymphoid organs and tumor. Depleting CD8 T cells abrogated the effects of NT-I7. Furthermore, NT-I7 treatment decreased progenitor cells in the bone marrow.

CONCLUSION

In orthotopic glioma-bearing mice, NT-I7 mitigates radiation-related lymphopenia, increases cytotoxic CD8 T lymphocytes systemically and in the tumor, and improves survival. A phase I/II trial to evaluate NT-I7 in patients with high-grade gliomas is ongoing (NCT03687957).