Cellectis Presents Pre-Clinical Data on TALEN®-edited Smart CAR T-cells Overcoming Key Challenges of Targeting Solid Tumors at SITC 2022

New York, NY – November 10, 2022 - Cellectis (the “Company”) (Euronext Growth: ALCLS - NASDAQ: CLLS), a clinical-stage biotechnology company using its pioneering gene-editing platform to develop life-saving cell and gene therapies, today announced that preclinical data will be presented on TALEN®-edited smart CAR T-cells overcoming key challenges of targeting solid tumors at the Society for Immunotherapy of Cancer’s (SITC) 37th Annual Meeting.

The data will be presented today in two poster sessions titled: “Multi-armored allogeneic MUC-1 CAR T-cells efficiently control triple negative breast cancer tumor growth” (Poster Number: 217) and “TALEN®-edited smart CAR T-cells leverage solid tumor microenvironment for specific and effective immunotherapy” (Poster Number: 325).

The poster presentations highlight the following preclinical data:

Multi-armored allogeneic MUC-1 CAR T-cells efficiently control triple negative breast cancer tumor growth

· This poster highlights TALEN®-edited smart CAR T-cells targeting MUC1- expressing solid tumors.

· MUC1 is a tumor-associated antigen that is overexpressed in triple-negative breast cancer (TNBC) and other solid tumor malignancies.

· MUC-1 CAR T-cells infiltrate tumors more efficiently and extend survival when enhanced with attributes catered towards the tumor microenvironment (TME) of TNBC tumors.

· TGFBR2 knock-out (KO) circumvents the inhibitory effects of TGFβ1, and IL-12 release follows CAR T-cell activation pattern restricting it to the tumor site for increased safety.

· Enhanced MUC-1 CAR T-cells could address some of the current challenges in development of CAR Ts for TNBC patients with unmet medical needs.

· Overall, we can efficiently generate allogeneic CAR T-cells and engineer them to overcome several key challenges of immune suppressive solid tumors.

TALEN®-edited smart CAR T-cells leverage solid tumor microenvironment for specific and effective immunotherapy

· This poster highlights innovative T-cell engineering strategies designed to increase the activity of CAR T-cells for solid tumors while mitigating toxicity risk.

· Therapeutic efficacy of CAR T-cell therapy has so far been restricted to only a few malignancies, with solid tumors proving to be especially recalcitrant to efficient therapy. Our TALEN®-based gene editing platform allows innovative T cell engineering strategies that can combat some of the challenges posed by CAR T cell development for solid tumors.

· Inducible expression of a tumor-antigen directed CAR by a constitutive CAR specific to TME cues greatly enhanced anti-tumor activity, while limiting ‘on target, off-tumor’ cytotoxicity. Additionally, CAR-induced gene expression could boost anti-tumor CART only within the TME.

· Cellectis’ gene editing strategies could increase CAR T cell persistence and anti-tumor activity while staying restricted to the tumor milieu.

· This proof-of-concept study demonstrates the feasibility of developing CART cell engineering strategies that can improve solid tumor targeting while mitigating potential safety risks, paving the way for clinical development.

Laurent Poirot, Ph.D., Senior Vice President Immunology at Cellectis, noted:

“Using our TALEN®-based gene editing platform, we have presented innovative T cell engineering strategies that can combat some of the challenges posed by CAR T cell development for solid tumors. We are mitigating potential safety risks, paving the way for clinical development for patients with unmet medical needs.”

Presentations will occur today, from 9:00AM until 9:00PM ET, Hall C.

A copy of both poster presentations will be available on Cellectis’ website here, shortly after the event.