Cellectis chairman and CEO André Choulika, PhD

Cellectis, which has built a clinical-phase pipeline consisting entirely of treatments that apply its proprietary TALEN® gene editing technology, says the U.S. patent issued to the company this month will facilitate the development of future development of future T-cell immunotherapy treatments based on CRISPR-Cas.

Cellectis CEO André Choulika, PhD, who is listed on the patent as a co-inventor, told GEN Edge that the patent reflects the company’s agnostic approach to gene editing by enabled the use of CRISPR Cas-9 for disabling the TCR gene in T cells.

The new patent does not signal that the company is giving up on the TALEN- (transcription activator-like effector nuclease) based gene editing incorporated into all of its clinical treatment candidates, all of which are in Phase I dose escalation or dose expansion, Choulika added.

“We don’t think that there is like any additional value added to having CRISPR in our current product in the clinic, and so we’ll stick to TALEN so far,” Choulika said. “But maybe in the future, we could potentially push a CRISPR product. That has not been decided yet, if we should do this or not, but it’s definitely an option that we will keep in mind.”

TALEN is used, Choulika said, because of its performance and precision, and its efficiency of use for gene replacement and gene correction, while CRISPR is on a par with TALEN for knocking out genes, and offers ease of use as well as for screening of libraries and guides.

Using “What’s Best”

“We’re totally technology agnostic. Therefore, each time there is a new technology that comes up, we at Cellectis are very open,” Choulika said. “At the basis we use what’s best. It depends exactly of the applications and where we want to go.”

Cellectis’ use of both gene editing technologies stretches about a decade. As GEN reported last year, Cellectis embraced TALEN technology in 2011, when Choulika told his employees that the Paris-based company was dropping the early genome editing platform called meganucleases that Choulika had been working on since the late 1980s, instead adopting TALENs.

“When CRISPR came out a year later, we got excited and started using it,” Choulika recalled recently, soon after he and colleagues read the seminal 2012 paper published by Jennifer Doudna, PhD, of the University of California, Berkeley, and colleagues. “When a new technology comes out that works in our hands, we will probably jump on it and get excited, like our scientists are passionate about it. And that’s what they do.”

Cellectis has been awarded U.S. Patent No. 10,584,352, “Methods for engineering T cells for immunotherapy by using RNA-guided Cas nuclease system.” The patent is intended to protect a method of developing genetically engineered, preferably non-alloreactive T-cells that involves several steps:

  • Providing primary human T-cells from a donor.
  • Genetically modifying the primary human T-cells to eliminate expression of the T-cell receptor (TCR), consisting of expressing in the cells a Cas9 endonuclease fused to a nuclear localization signal (NLS), and a guide RNA that directs said endonuclease to at least one targeted locus encoding the TCR in the T-cell genome.
  • Expanding the genetically modified T-cells.
  • Administering at least 10,000 of the expanded genetically modified T-cells to a patient.

The engineered T-cells are also intended to express chimeric antigen receptors (CARs) to redirect their immune activity towards malignant or infected cells.

Looking beyond Cas9

The patent covers use of guided nucleases beyond Cas9, including Cas12 and any other Cas guides, Choulika said.

“The invention opens the way to standard and affordable adoptive immunotherapy strategies using T-Cells for treating cancer and viral infections,” the patent states.

The new U.S. patent expands upon two U.S. patents issued to the company in 2018, No. 9,855,297 and No. 9,890,393. Both cover the invention of certain uses of RNA-guided endonucleases, such as Cas9 or Cpf1, for the genetic engineering of T-cells—and both claim methods by which T-cells are gene edited using transient expression of CRISPR/Cas9 components.

The just-issued U.S. patent is also essentially similar to a European patent granted to Cellectis on August 2, 2017. Listed with Choulika as inventors of both patents were two other Cellectis executives: Philippe Duchateau, PhD, chief scientific officer; and Laurent Poirot, PhD, VP, Immunology Department.

The European patent—EP3004337, which also claims a method of preparing T-cells for immunotherapy using the CRISPR-Cas9 system—has withstood an anonymous opposition procedure that was initiated in May 2018, and decided by the EPO in Cellectis’ favor in November 2019.

Two months later in January, the EPO granted Cellectis another patent: EP3116902, which claims “an engineered isolated CAR T-cell, which expression of beta 2-microglobulin (B2M) is inhibited, while at least one gene encoding a component of the T-cell receptor (TCR) is inactivated.”

Inventors of EP3116902 include Duchateau, Poirot, and two other Cellectis executives: David Sourdive, PhD, EVP of Strategic Initiatives, and Jean-Pierre Cabaniols, PhD, Head of Analytical Department.