Lucas Rebuffet

Natural killer (NK) cells are innate lymphoid cells (ILCs) contributing to immune responses to microbes and tumors. Historically, their classification hinged on a limited array of surface protein markers. Here, we used single-cell RNA sequencing (scRNA-seq) and cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) to dissect the heterogeneity of NK cells. We identified three prominent NK cell subsets in healthy human blood: NK1, NK2 and NK3, further differentiated into six distinct subgroups. Our findings delineate the molecular characteristics, key transcription factors, biological functions, metabolic traits and cytokine responses of each subgroup. These data also suggest two separate ontogenetic origins for NK cells, leading to divergent transcriptional trajectories. Furthermore, we analyzed the distribution of NK cell subsets in the lung, tonsils and intraepithelial lymphocytes isolated from healthy individuals and in 22 tumor types. This standardized terminology aims at fostering clarity and consistency in future research, thereby improving cross-study comparisons.

Decision making in immuno-oncology is pivotal to adapt therapy to the tumor microenvironment (TME) of the patient among the numerous options of monoclonal antibodies or small molecules. Predicting the best combinatorial regimen remains an unmet medical need. Here, we report a multiplex functional and dynamic immuno-assay based on the capacity of the TME to respond to ex vivo stimulation with twelve immunomodulators including immune checkpoint inhibitors (ICI) in 43 human primary tumors. This "in sitro" (in situ/in vitro) assay has the potential to predict unresponsiveness to anti-PD-1 mAbs, and to detect the most appropriate and personalized combinatorial regimen. Prospective clinical trials are awaited to validate this in sitro assay.

NK cells offer a promising alternative to T cell therapies in cancer. We evaluated IPH6501, a clinical-stage, tetraspecific NK cell engager (NKCE) armed with a non-alpha IL-2 variant (IL-2v), which targets CD20 and was developed for treating B cell non-Hodgkin lymphoma (B-NHL). CD20-NKCE-IL2v boosts NK cell proliferation and cytotoxicity, showing activity against a range of B-NHL cell lines, including those with low CD20 density. Whereas it presented reduced toxicities compared with those commonly associated with T cell therapies, CD20-NKCE-IL2v showed greater killing efficacy over a T cell engager targeting CD20 in in vitro preclinical models. CD20-NKCE-IL2v also increased the cell surface expression of NK cell-activating receptors, leading to activity against CD20-negative tumor cells. In vivo studies in nonhuman primates and tumor mouse models further validated its efficacy and revealed that CD20-NKCE-IL2v induces peripheral NK cell homing at the tumor site. CD20-NKCE-IL2v emerges as a potential alternative in the treatment landscape of B-NHL.

Committed progenitors with innate lymphoid cell (ILC) developmental potential are present in the fetus and bone marrow (BM). However, how fetal and BM hematopoiesis temporally and spatially contribute to ILC pools remains unclear. Here, we elucidated the distinct origins and developmental pathways of extramedullary and intramedullary ILCs in mice during ontogeny. ILC-restricted hematopoiesis is initiated in the fetal liver (FL), and then FL-derived PD-1 + ILC precursors (ILCPs) seed fetal lung and intestine. Organ niches determine the commitment of ILCPs to downstream precursors, including bipotent ILC1-ILC3 precursors (ILC1/3Ps), which preferentially reside in the liver and intestine, and ILC2 precursors (ILC2Ps), which are found predominantly in the lung. These precursors persist in adulthood and contribute to local ILC pools in a BM-independent manner. In contrast, intramedullary ILC2Ps and ILC2s rely on BM hematopoiesis. Thus, our study demonstrates that extramedullary and intramedullary ILCs have different origins and provides a comprehensive framework for ILC developmental dynamics.