A compound chimeric antigen receptor strategy for targeting multiple myeloma

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• Current chimeric antigen receptor (CAR) T-cell therapies for multiple myeloma targeting BCMA (CD269) show initial efficacy but are limited by antigen loss and relapse.
• Relapse in multiple myeloma is often due to the emergence of BCMA-negative or -low expressing cells.
• Improved CAR T-cell designs are needed to address antigen escape and enhance long-term persistence.

Purpose of the Study:

• To develop and evaluate a novel compound CAR (cCAR) T-cell therapy targeting two distinct multiple myeloma antigens, BCMA and CS1.
• To assess the in vitro and in vivo anti-tumor activity of the dual-targeting cCAR T-cells against multiple myeloma.
• To determine if targeting both BCMA and CS1 can overcome antigen loss and improve therapeutic outcomes compared to single-target CARs.

Main Methods:

• Development of a compound CAR (cCAR) T-cell construct with two independent receptors targeting BCMA and CS1.
• In vitro assessment of cCAR T-cell cytotoxicity against multiple myeloma cell lines expressing BCMA and/or CS1.
• In vivo evaluation of cCAR T-cell efficacy and survival in multiple mouse models of multiple myeloma, including mixed antigen-expressing populations.

Main Results:

• The developed cCAR T-cells demonstrated potent and directed cytotoxicity against both BCMA-positive and CS1-positive multiple myeloma cells in vitro.
• In vivo studies using mouse models showed superior anti-tumor activity and improved survival with cCAR T-cells compared to single-target CAR T-cells.
• The cCAR T-cells effectively targeted mixed cell populations, indicating efficacy against both antigen-positive and potentially antigen-loss variants.

Conclusions:

• Compound targeting of BCMA and CS1 using cCAR T-cells is a promising strategy to enhance therapeutic responses in multiple myeloma.
• This dual-targeting approach may overcome antigen loss, a common mechanism of relapse, and broaden CAR therapy coverage.
• Further development of this cCAR T-cell therapy could lead to more durable remissions and improved outcomes for multiple myeloma patients.