Patient derived anti-CD19 chimeric antigen receptor-T (CAR-T) cells are a powerful tool in achieving a complete remission in a range of B-cell malignancies, most notably B-acute lymphoblastic leukaemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL). However, there are limitations, including inability to manufacture CAR-T cells from the patient’s own T cells, disease progression and death prior to return of engineered cells. T cell dysfunction is known to occur in cancer patients, and several groups have recently described differences in CAR-T cells generated from chronic lymphocytic leukaemia (CLL) patients compared with those from a healthy donor. This is thought to contribute to the low response rate in this disease group. Healthy donor, gene-edited CAR-T cells which do not require human leucocyte antigen (HLA) matching have the potential to provide an ‘off the shelf’ product, overcoming the manufacturing difficulties of producing CAR-T cells for each individual patient. They may also provide a more functional, potent product for malignancies such as CLL, where T cell dysfunction is common and frequently cannot be fully reversed during the manufacturing process. Here we review the potential benefits and obstacles for healthy donor, allogeneic CAR-T cells.

Recent transcriptomic-based analysis of diffuse large B cell lymphoma (DLBCL) has highlighted the clinical relevance of LN fibroblast and tumor-infiltrating lymphocyte (TIL) signatures within the tumor microenvironment (TME). However, the immunomodulatory role of fibroblasts in lymphoma remains unclear. Here, by studying human and mouse DLBCL-LNs, we identified the presence of an aberrantly remodeled fibroblastic reticular cell (FRC) network expressing elevated fibroblast-activated protein (FAP). RNA-Seq analyses revealed that exposure to DLBCL reprogrammed key immunoregulatory pathways in FRCs, including a switch from homeostatic to inflammatory chemokine expression and elevated antigen-presentation molecules. Functional assays showed that DLBCL-activated FRCs (DLBCL-FRCs) hindered optimal TIL and chimeric antigen receptor (CAR) T cell migration. Moreover, DLBCL-FRCs inhibited CD8⁺ TIL cytotoxicity in an antigen-specific manner. Notably, the interrogation of patient LNs with imaging mass cytometry identified distinct environments differing in their CD8⁺ TIL-FRC composition and spatial organization that associated with survival outcomes. We further demonstrated the potential to target inhibitory FRCs to rejuvenate interacting TILs. Cotreating organotypic cultures with FAP-targeted immunostimulatory drugs and a bispecific antibody (glofitamab) augmented antilymphoma TIL cytotoxicity. Our study reveals an immunosuppressive role of FRCs in DLBCL, with implications for immune evasion, disease pathogenesis, and optimizing immunotherapy for patients.

Multiple myeloma remains an incurable plasma cell malignancy despite the rapidly evolving treatment landscape. Chimeric antigen receptor T cells targeted against BCMA have recently shown great promise in relapsed refractory multiple myeloma; however, all patients ultimately still progress from their disease. Lack of CAR T-cell persistence, impaired T-cell fitness in autologous CAR T-cell products and the presence of an immunosuppressive bone marrow (BM) microenvironment are contributory factors to treatment failure. We generated anti-BCMA CAR T cells from healthy donors (HD) and patients with multiple myeloma at different stages of disease to compare their T-cell profile, fitness, and cytotoxic activity in preclinical studies. We also used an ex vivo assay with multiple myeloma BM biopsies from distinct genomic subgroups to test the efficacy of HD-derived CAR T cells in a clinically relevant model. HD volunteers showed increased T-cell counts, higher CD4/CD8 ratio, and expanded naïve T-cell population compared with patients with multiple myeloma. After anti-BCMA CAR T-cell production, patients with relapsed multiple myeloma had lower frequencies of CAR+ T cells, decreased central memory phenotype, and increased checkpoint inhibitory markers compared with HD-derived products, which compromised their expansion and cytotoxicity against multiple myeloma cells in vitro. Importantly, HD-derived CAR T cells efficiently killed primary multiple myeloma cells within the BM microenvironment of different multiple myeloma genomic subgroups and their cytotoxic activity could be boosted with gamma secretase inhibitors. In conclusion, allogeneic anti-BCMA CAR T cells are a potential therapeutic strategy for patients with relapsed multiple myeloma and should be further developed in the clinic.Significance: Multiple myeloma is an incurable cancer of the plasma cells. A new therapy with anti-BCMA CAR T cells — the patient's own T cells genetically engineered to find and kill myeloma cancer cells — has shown encouraging results. Unfortunately, patients still relapse. In this study, we propose to use T cells from HD volunteers, which have a stronger T-cell fitness, higher cancer killing capacity, and are ready to be administered when needed.