22O - Development of anti-CD38-CAR allogeneic γδ T cells as an off-the-shelf use for myeloma

Background

CAR-T cell therapy has shown great success compared to conventional treatments for hematopoietic malignancies. Anti-BCMA-CAR-T cell therapy is effective in patients with refractory multiple myeloma treated with anti-CD38 antibody drugs. However, it has a highly relapsed rate and requires time and costs due to individualized medicine. Therefore, we attempted to establish an off-the-shelf, highly effective CAR-T cell therapy by generating anti-CD38-CAR-γδ T cells using allogeneic γδ T cells that attack targets in a non-MHC-restricted manner.

Methods

PBMCs were isolated from peripheral blood of healthy donors and cultured in medium with IL-2 and zoledronic acid for 4 days to expand γδ T cells. Then the anti-CD38-CAR gene was retrovirally transduced. The antitumor effects of anti-CD38-CAR-γδ T cells in vitro were examined by co-culture with KMM1 and MM1.S cells. The antitumor effect in vivo was evaluated using NOG mice implanted with luciferase-labeled KMM1 cells.

Results

The expression of CD38 in γδ T cells was very weak before and after activation. This was a major different characteristic from that of the ab typed T cells, facilitating the introduction of anti-CD38-CAR. In vitro, it significantly damaged two different myeloma cell line cells, killing more than 90% of targets at an E: T ratio of 1:5 and co-culture time of 24 hours. Surprisingly, this cytotoxicity was observed even in the presence of anti-CD38 antibody drugs, which are clinically used, suggesting that it can be used after or in combination with anti-CD38-antibodies. Activity and CAR expression were maintained even after freezing and thawing and after one month of culture, indicating properties that are expected to be used in off-the-shelf applications. In vivo, tumor progression was greatly suppressed, and the survival period of CAR-administered mice was significantly extended.

Conclusions

Anti-CD38-CAR-γδ T cells exerted strong cytotoxicity against myeloma cells in vitro and in vivo, and their activity did not decrease even in the presence of anti-CD38 antibody drugs. Anti-CD38-CAR-allogeneic γδ T-cell therapy is expected to be a highly effective and feasible treatment for patients with relapsed and refractory myeloma as an off-the-shelf use.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.