Cellectis Announces First Patient Treated in Phase 1 Trial of UCART19 in Pediatric Acute B Lymphoblastic Leukemia (B-ALL)

NEW YORK–(BUSINESS WIRE)– Regulatory News:

Cellectis (Paris:ALCLS) (NASDAQ:CLLS) (Alternext: ALCLS – Nasdaq: CLLS),
a biopharmaceutical company focused on developing immunotherapies based
on gene edited CAR T-cells (UCART), today announced that the first
patient has been treated in the Phase I study of UCART19 in pediatric
acute B lymphoblastic leukemia (B-ALL) at the University College of
London (UCL). This UCART19 clinical trial is sponsored by Servier in
close collaboration with Pfizer.

The pediatric Phase I is an open label, non-comparative, monocenter
study to evaluate the safety and ability of UCART19 to induce molecular
remission in pediatric patients with relapsed or refractory CD19
positive B-cell acute lymphoblastic leukemia ahead of planned allogeneic
haematopoeitic stem cell transplantation (allo-HSCT).

Cellectis will receive a milestone payment from Servier of an
undisclosed amount.

About UCART19

UCART19 is an allogeneic CAR T-cell product candidate developed for
treatment of CD19-expressing hematological malignancies, gene edited
with TALEN®. UCART19 is initially being developed in chronic lymphocytic
leukemia (CLL) and acute lymphoblastic leukemia (ALL). Cellectis’
approach with UCART19 is based on the preliminary positive results from
clinical trials using autologous products based on the CAR technology,
and has the potential to overcome the limitation of the current
autologous approach by providing an allogeneic, frozen, “off-the-shelf”
T-cell based medicinal product.

In November 2015, Servier acquired the exclusive rights to UCART19 from
Cellectis. Following further agreements, Servier and Pfizer began
collaborating on a joint clinical development program for this cancer
immunotherapy. Pfizer has exclusive rights from Servier to develop and
commercialize UCART19 in the United States, while Servier retains
exclusive rights for all other countries.

About Cellectis

Cellectis is a biopharmaceutical company focused on developing
immunotherapies based on gene edited CAR-T cells (UCART). The company’s
mission is to develop a new generation of cancer therapies based on
engineered T-cells. Cellectis capitalizes on its 16 years of expertise
in genome engineering – based on its flagship TALEN® products and
meganucleases and pioneering electroporation PulseAgile technology – to
create a new generation of immunotherapies. CAR technologies are
designed to target surface antigens expressed on cells. Using its
life-science-focused, pioneering genome-engineering technologies,
Cellectis’ goal is to create innovative products in multiple fields and
with various target markets. Cellectis S.A. is listed on the Nasdaq
Global Market (ticker: CLLS) and on the NYSE Alternext market (ticker:
ALCLS). To find out more about us, visit our website: www.cellectis.com

Talking about gene editing? We do it.
TALEN® is a registered
trademark owned by the Cellectis Group.

Disclaimer

This press release and the information contained herein do not
constitute an offer to sell or subscribe, or a solicitation of an offer
to buy or subscribe, for shares in Cellectis in any country. This press
release contains forward-looking statements that relate to the Company’s
objectives based on the current expectations and assumptions of the
Company’s management only and involve risk and uncertainties that could
cause the Company to fail to achieve the objectives expressed by the
forward-looking statements above.

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