Next Generation CD44v6-Specific CAR-NK Cells Effective against Triple Negative Breast Cancer

Abstract

There is a medical need to develop new and effective therapies against triple-negative breast cancer (TNBC). Chimeric antigen receptor (CAR) natural killer (NK) cells are a promising alternative to CAR-T cell therapy for cancer. A search for a suitable target in TNBC identified CD44v6, an adhesion molecule expressed in lymphomas, leukemias and solid tumors that is implicated in tumorigenesis and metastases. We have developed a next-generation CAR targeting CD44v6 that incorporates IL-15 superagonist and checkpoint inhibitor molecules. We could show that CD44v6 CAR-NK cells demonstrated effective cytotoxicity against TNBC in 3D spheroid models. The IL-15 superagonist was specifically released upon recognition of CD44v6 on TNBC and contributed to the cytotoxic attack. PD1 ligands are upregulated in TNBC and contribute to the immunosuppressive tumor microenvironment (TME). Competitive inhibition of PD1 neutralized inhibition by PD1 ligands expressed on TNBC. In total, CD44v6 CAR-NK cells are resistant to TME immunosuppression and offer a new therapeutic option for the treatment of BC, including TNBC.

Next-Generation CEA-CAR-NK-92 Cells against Solid Tumors: Overcoming Tumor Microenvironment Challenges in Colorectal Cancer

“…The reduced activation might be due to differences between CAR format and antibody format [43], the epitope position within the CEA molecule directly impacting receptor-mediated CAR T-cell activation [44], or the role of adhesion molecules in efficient CAR recognition [45]. As has previously been described, we have identified and validated a natu curring splice variant of human PD1 checkpoint molecule (PD1x) that lacks the c mic signaling domain [39]. This PD1x variant acts as a competitive inhibitor to P also minimize off-target interactions of unwanted immune response.…”

“…As has previously been described, we have identified and validated a naturally occurring splice variant of human PD1 checkpoint molecule (PD1x) that lacks the cytoplasmic signaling domain [39]. This PD1x variant acts as a competitive inhibitor to PD1 and also minimize off-target interactions of unwanted immune response.…”

Modulation of the tumor microenvironment and mechanism of immunotherapy-based drug resistance in breast cancer

“…CT-0508, an anti-HER2 CAR-M is in phase I trial for refractory HER2 + breast cancer patients with a parallel assignment intervention model (NCT04660929) [ 106 ] ( Table 1 ) . CD44v6-specific CAR-NK cells have been found to be effective in a mammosphere model of TNBC [ 107 ]. However, engineered immune cell application also involves several limitations.…”

Next‐generation chimeric antigen receptors for T‐ and natural killer‐cell therapies against cancer

“…67 Another suicide system that has been used in CAR NK cells is the herpes simplex virus (HSV) thymidine kinase (HSV TK), which converts ganciclovir into a toxic product. 166 Other strategies to control CAR expression incorporate a reversible OFF-switch. For example, CARs engineered with a C2H2 zinc finger degron motif can be induced to interact with an E3 ubiquitin ligase by lenalidomide, leading to CAR proteasomal degradation (Figure 3E).…”