Natural Killer cells armed with engineered anti-Her2 antibody or Her2-CAR-NK cells show enhanced cytotoxicity over naked NK cells against Her2-overexpressing breast cancer — ASN Events
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  3. Natural Killer cells armed with engineered anti-Her2 antibody or Her2-CAR-NK cells show enhanced cytotoxicity over naked NK cells against Her2-overexpressing breast cancer

Natural Killer cells armed with engineered anti-Her2 antibody or Her2-CAR-NK cells show enhanced cytotoxicity over naked NK cells against Her2-overexpressing breast cancer (#131)

Vera TC Valckx 1 2 , Meric Birben 1 , Nicky A Beelen 1 2 , Jessy Presumey 3 , Bénédicte Fauvel 3 , Roel GJ Klein Wolterink 1 , Gerard MJ Bos 1 4 , Lotte Wieten 2 , Wilfred TV Germeraad 1 4
  1. Department of Internal Medicine, Division of Hematology, Maastricht University Medical Center, Maastricht, Netherlands
  2. Department of Transplantation Immunology, Maastricht University Medical Center+, Maastricht, the Netherlands
  3. Cytea Bio, Grabels, France
  4. CiMaas BV, Maastricht, the Netherlands

Natural killer (NK)-based immunotherapy has emerged as a novel treatment modality for solid cancers. The ADCC inducing antibody trastuzumab enhances NK cell activation and cytotoxicity against Her2-overexpressing breast cancer. However, trastuzumab causes unwanted side effects and the efficacy of combination therapy may depend on the ability of both the antibody and NK cells to distribute to the tumor and find their targets at the same time.

Here we show and compare two alternative strategies to enhance NK cell cytotoxicity against Her2-overexpressing breast cancer: 1. by pre-arming expanded NK cells with a genetically Fc-modified Her2-targeting antibody (Pin-Her2 with Her2-binding sequence from Trastuzumab) allowing persistent binding to CD16 on NK cells. 2. CAR-NK cells with the Her2-binding sequence from Trastuzumab. Using CRISPR/Cas9 and AAV6 vector, we performed precise CAR integration into the AAVS1 safe harbor site.

Clinical grade expanded NK cells from peripheral blood of healthy donors were armed with the Pin-Her2 antibody or transduced with a HER2 CAR containing the CD3z and 4-1BBL intracellular domains. NK cell degranulation (CD107a) was measured by flow cytometry after 4-hour coculture with breast cancer target cells. Cytotoxicity was measured with the Caspase-3/7 fluorescent apoptosis dye using IncuCyte live-cell imaging and fluorescently labelled breast cancer cell lines were cocultured with Pin-, CAR-, or naked NK cells with or without trastuzumab.

Expanded NK cells were efficiently armed with the Pin-Her2 antibody or transfected with CARs. Similarly to unarmed NK cells combined with trastuzumab, Pin-Her2-armed NK cells showed enhanced degranulation against Her2-overexpressing cell line SKBR3, compared to unarmed NK cells. Moreover, Pin-Her2-armed NK cells and Her2-CAR-NK cells induced a more rapid elimination of SKBR3 cells compared to unarmed NK cells, but not of Her2low MCF7 cells. 

Our results demonstrate the potential of equal numbers of both modified NK cells for Her2-overexpressing breast cancers over naked NK cells.