Dr Di Meo on the Rationale for Developing LILRB4–Directed CAR T-Cell Therapy in Multiple Myeloma

Francesco Di Meo, PhD, postdoctoral research fellow, Moffitt Cancer Center, discusses the role of the immunoreceptor LILRB4 in the tumor microenvironment, as well as highlights the rationale for targeting this marker through CAR T-cell development in multiple myeloma.

Di Meo and his colleagues developed a pipeline to identify biologically and therapeutically relevant targets for immunotherapy development in multiple myeloma by using mass-spectrometry analyses from 7 multiple myeloma cell lines and RNA-seq data from over 900 patients with multiple myeloma. From a pool of 4,000 candidates, multiple myeloma, emerged as a promising target. Multiple myeloma is a tyrosine-based inhibition motif-containing receptor that functions as an immune checkpoint on myeloid cells and has implications in various immune diseases.

LILRB4 shows low expression in normal tissues but is highly expressed in many primary patient samples and myeloma cell lines, similar to BCMA, making it a significant marker for multiple myeloma, Di Meo states. LILRB4 has also been implicated in the proliferation of multiple myeloma cells and has shown an immunomodulatory role in diseases like monocytic acute myeloid leukemia (AML), where it mediates T-cell inhibition and leukemia cell infiltration, he adds.

Building on these findings, investigators aimed to investigate the functional role of LILRB4 in multiple myeloma and explore the development of CAR T-cell therapies targeting LILRB4, Di Meo continues. This approach seeks to leverage the specific expression patterns and immunomodulatory properties of LILRB4 in multiple myeloma to design targeted therapies that can enhance immune responses against myeloma cells, he explains.

In this study, multiple CAR constructs developed to target LILRB4 demonstrated specific killing of myeloma cell lines in vitro, including cell lines with resistance to conventional therapies.

Overall findings from the study reinforce LILRB4's role as a negative immune receptor in multiple myeloma. Future studies will focus on validating these findings and exploring the therapeutic potential of targeting LILRB4 with CAR T-cell therapies in myeloma.

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Francesco Di Meo, PhD, discusses the rationale for targeting LILRB4 through CAR T-cell therapy in multiple myeloma.

Dr Di Meo on the Potential Efficacy of LILRB4-Targeted CAR T-Cell Therapy in Multiple Myeloma

Francesco Di Meo, postdoctoral research fellow, Moffitt Cancer Center, discusses the potential efficacy of CAR T-cells targeting the immunoreceptor LILRB4 in multiple myeloma.

Investigators launched a study in order to elucidate the functional role of LILRB4 in multiple myeloma, as well as to develop CAR T-cells targeting LILRB4.

Analysis of RNA sequencing data from patients with multiple myeloma revealed elevated LILRB4 expression in patients with high-risk cytogenetics, such as t:(14;16), t:(14;20), and t:(8;14) translocations, compared with patients without genomic abnormalities, Di Meo begins.Additionally, functional studies involving genetic depletion of LILRB4 in U266/KMS11/OPM2 myeloma cell lines showed no significant difference in cell proliferation compared with controls, as assessed by in vitro cell growth assays and migration assays using porous membranes, Di Meo explains.

Further investigation using LILRB4 knockout and overexpressing U266 myeloma cells identified approximately 3,000 differentially expressed genes compared with controls, suggesting potential extrinsic effects, he expands. Co-culture experiments with T-cells from healthy donors and LILRB4 knockout or overexpressing U266 cells revealed decreased T-cell proliferation in the presence of LILRB4 overexpressing cells, while proliferation increased with LILRB4 knockout cells, Di Meo elucidates.This effect was associated with changes in CD25 expression on T-cells, indicating a negative immune regulatory role of LILRB4, he notes.

Multiple CAR constructs targeting LILRB4 were also developed, showing specific killing of myeloma cell lines in vitro, including those resistant to conventional therapies. Notably, no effect was observed on LILRB4 null cells, Di Meo continues.

Overall, these findings suggest that LILRB4 acts as a negative immune receptor, mediating T-cell suppression in multiple myeloma. The development of LILRB4-targeting CAR T-cell therapy holds promise as a therapeutic approach, particularly for high-risk patients, he states. This indicates the potential clinical significance of targeting LILRB4 in future multiple myeloma treatment strategies, Di Meo concludes.

Francesco Di Meo, PhD, discusses the potential efficacy of CAR T-cells targeting the immunoreceptor LILRB4 in multiple myeloma.

Francesco Di Meo, PhD

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Dr Di Meo on the Rationale for Developing LILRB4–Directed CAR T-Cell Therapy in Multiple Myeloma

Dr Di Meo on the Potential Efficacy of LILRB4-Targeted CAR T-Cell Therapy in Multiple Myeloma