The CRISPR/Cas9 technique enables inactivation of virtually any gene of the genome. By designing a specific 20 base-pair sequence complementary to the targeted DNA sequence, an RNA fragment named single-guide RNA (sgRNA) allows for recruiting the Cas9 endonuclease resulting in blunt ends DNA fragments and gene disruption (Figure 1).
During the outgoing phase of the action (from November 2015 to October 2016) that took place at the National Institute of Health (Bethesda, MD, USA), nine peripheral T-cell lymphoma (PTCL) cell lines have been engineered to express the Streptococcus pyogenes Cas9 enzyme : HuT78, HuT102, MyLa, HH and Sez4 (cutaneous PTCL); OCI-Ly12 and OCI-Ly13.2 (nodal PTCL); SUDHL1 and DEL (ALK+ anaplastic PTCL).
During the return phase at the Lyon Sud Hospital in France, whole genome CRISPR/Cas9 screens have been performed in all of these lines (Figure 2) and potential therapeutic targets have been individually confirmed.
Several genes essential for survival have been identified in keeping with the objectives of the action: BCL-xL, an anti-apoptotic gene, was found to be of utmost relevance for therapeutic purposes in PTCL, as well as CFLAR, a gene inhibiting the extrinsic apoptotic pathway in various cell types. Based on those pre-clinical data, new early phase trials using specific inhibitors are expected to be set up in the next few months. Many other genes of putative therapeutic importance have been also identified and are in patenting process.
Results have been presented at many national and international meetings (International Conference on Malignant Lymphoma, Lugano, June 2017; Lyon Center for Cancer Research, November 2017; Imagine Workshop, Necker Hospital, Paris, January 2018) reaching a broad audience of researchers, industrial partners, and patients' associations.
