Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Background:

In the past years, the treatment of acute myeloid leukemia (AML) has been significantly shifted towards the development of targeted approaches. Nonetheless, clinical translation of novel immunotherapeutic strategies such as chimeric antigen receptor (CAR) T-cells in AML is still at an early stage. Given the heterogeneity of such disease, major challenges include immune escape and disease relapse, which demand for further improvements in the CAR design. To overcome such hurdles, we have invented the switchable, flexible and programmable adaptor RevCAR platform. This consists of T-cells engineered with RevCARs that are primarily inactive as they express an extracellular short peptide epitope incapable of recognizing surface antigens. RevCAR T-cells can be redirected to tumor antigens and controlled by bispecific antibodies cross-linking RevCAR T- and tumor cells resulting in tumor lysis. Remarkably, the RevCAR platform enables combinatorial tumor targeting following Boolean logic gates in which two separate RevCARs with different specificities can be simultaneously expressed and used to accomplish dual gated targeting of prominent AML antigens such as CD33 and CD123. We herein show for the first time the applicability of the RevCAR platform to target myeloid malignancies such as AML.

Methods:

Binding, functionality and proof-of-concept for combinatorial tumor targeting using the RevCAR system was assessed using both in vitro and in vivo models in different settings. For that, flow cytometry-based, cytokine release and cytotoxicity assays were performed using established AML cell lines or patient-derived material.

Results:

We have proven that AML cell lines as well as patient-derived AML blasts could be efficiently killed by redirected RevCAR T-cells targeting CD33 and CD123 in a flexible manner. Furthermore, by targeting both antigens, an AND gate logic targeting could be achieved using the RevCAR platform. This is a particular important approach to overcome existing or treatment related tumor escape variants and to tackle AML cancer heterogeneity.

Conclusions:

These accomplishments validate the preclinical versatility and controllability of the RevCAR platform embedded in one single system thereby paving the way for an improved and personalized immunotherapy of AML patients.