BCMA- and CST6-specific CAR T cells lyse multiple myeloma cells and suppress murine osteolytic lesions
Fumou Sun, … , John D. Shaughnessy Jr., Fenghuang Zhan
Fumou Sun, … , John D. Shaughnessy Jr., Fenghuang Zhan
Published October 26, 2023
Citation Information: J Clin Invest. 2024;134(1):e171396. https://doi.org/10.1172/JCI171396.
View: Text | PDF
Research Article Hematology Oncology Article has an altmetric score of 7

BCMA- and CST6-specific CAR T cells lyse multiple myeloma cells and suppress murine osteolytic lesions

Abstract

We have previously demonstrated that cystatin E/M (CST6), which is elevated in a subset of patients with multiple myeloma (MM) lacking osteolytic lesions (OLs), suppresses MM bone disease by blocking osteoclast differentiation and function. CST6 is a secreted type 2 cystatin, a cysteine protease inhibitor that regulates lysosomal cysteine proteases and the asparaginyl endopeptidase legumain. Here, we developed B cell maturation antigen (BCMA) CST6 chimeric antigen receptor T cells (CAR-T cells), which lysed MM cells and released CST6 proteins. Our in vitro studies show that these CAR-T cells suppressed the differentiation and formation of tartrate-resistant acid phosphatase–positive (TRAP+) osteoclasts. Using xenografted MM mice, bioluminescence images showed that both BCMA–CAR-T and BCMA–CST6–CAR-T cells inhibited MM growth to a similar extent. Reconstructed micro–computed tomography images revealed that BCMA–CST6–CAR-T cells, but not BCMA–CAR-T cells, prevented MM-induced bone damage and decreased osteoclast numbers. Our results provide a CAR-T strategy that targets tumor cells directly and delivers an inhibitor of bone resorption.

Authors

Fumou Sun, Yan Cheng, Jin-Ran Chen, Visanu Wanchai, David E. Mery, Hongwei Xu, Dongzheng Gai, Samer Al Hadidi, Carolina Schinke, Sharmilan Thanendrarajan, Maurizio Zangari, Frits van Rhee, Guido Tricot, John D. Shaughnessy Jr., Fenghuang Zhan

×

Figure 5

BCMA–CST6–CAR-T cells suppress MM1.S cell growth in vivo.

Options: View larger image (or click on image) Download as PowerPoint
BCMA–CST6–CAR-T cells suppress MM1.S cell growth in vivo. (A) Schematic ...
(A) Schematic of the experimental plan. NSG mice were administered 1.5 × 106 MM cells via i.v. injection. On day seven, 1.5 × 106 CAR-T cells were administered after injection of MM cells. Myeloma progression was monitored until the mice developed hind limb paralysis. (B) Tumor burden was evaluated by bioluminescence imaging of MM1.S cell–bearing mice treated with MOCK–CAR-T, BCMA–CAR-T, or BCMA–CST6–CAR-T cells. (C) Quantitative analysis of bioluminescence intensity (n = 5). (D) Mouse serum levels of CST6 protein detected by ELISA (n = 5). (E) Mouse serum levels of calcium detected by ELISA (n = 5). (F) Mouse serum levels of PTHrP detected by ELISA (n = 5). (G) Kaplan-Meier disease progression analysis of CAR-T treatment in NSG models (n = 5). Data represent the mean ± SD. *P < 0.05, **P < 0.01, and ***P < 0.001, by 1-way ANOVA (C–F) and log-rank test (G); NS = P > 0.05.