1060P - Balance of CD36+ and CD16+ monocytes controls TLR-mediated cytokine release syndrome and MHC-dependent antitumor responses in EpCAM CAR T cell therapy for gastrointestinal cancers

Background

EpCAM is a prominent cancer antigen expressed in gastrointestinal cancers. Our clinical trial (NCT05028933 and ChiCTR2100047129), comprising 12 patients, provides the first evidence that EpCAM CAR-T cells display promising efficacy against gastric cancer (disease control rate: 66.7%). During the trial, varying grades of cytokine release syndrome (CRS),occurred in 66.7% of patients. Nevertheless, the current understanding of the mechanism of CRS is limited. As the severity of CRS varies among patients receiving CAR-T therapy, identifying immunological profiles that are relevant to CRS may provide opportunities to screen patients at lower risk to improve the safety of CAR-T treatment. Targeting monocytes could offer novel perspectives for managing CAR-T therapy-induced CRS. However, the specific monocyte subsets and underlying mechanisms responsible for CRS-associated cytokine production are not yet fully understood.

Methods

Human peripheral blood mononuclear cells (PBMCs) were isolated from 2ml whole blood using Ficoll density gradient centrifugation. A Single-cell sequencing was performed using the GemCodeTM single-cell platform and Chromium Single Cell 5′ Reagent Kit (10× Genomics). Hu-PBL NOG mice were generated by injecting 10 million human peripheral blood mononuclear cells into NOG-MHCI/II-2KO mice. CAR-T cells were administered via tail vein when tumor volume reached 100 mm³.

Results

CD36⁺ monocyte cell numbers were significantly increased in CRS patients while CD16⁺ monocytes increased in response patients. Our data indicated activation of the antigen presentation in CD16⁺ monocytes or Toll-like receptor signaling in CD36⁺ monocytes may determine cytokine release syndrome and adaptive immune responses in CAR T-cell therapy.

Conclusions

We present valuable insights into the pathophysiology of CRS and suggest that TLR4 on CD36⁺ monocytes is a promising target for managing CRS, which offers a new strategy for mitigating the side effects of CAR-T therapy. We also highlight the role of innate immune components, particularly CD16⁺ monocytes, in achieving optimal CAR-T treatment efficacy through antigen processing and presentation.

Clinical trial identification

The study had a classic 3+3 design for each indication trial, with separate EpCAM CAR-T cell (IMC001) dose escalations for monotherapy. We report the first dosage group in advanced colon cancers (NCT05028933) and gastric cancers (ChiCTR2100047129).

Editorial acknowledgement

Legal entity responsible for the study

Tianhang Luo and Shanghai Changhai hospital.

Funding

Suzhou Immunofoco Biotechnology Co., Ltd.

Disclosure

All authors have declared no conflicts of interest.