The CD28 costimulatory role becomes particularly manifest under the poorly inflammatory conditions often encountered in tumor draining
lymph nodes and the
tumor microenvironment. Anti-tumoral
T cell responses have thus a great reliance on CD28 signalling. The possibility of inducing
high potential antitumor CAR-
T cell responses independently of CD28 pathway engagement by CD80 and CD86 represents thus an appealing approach. Now, the inventors surprisingly show that the mere presence in normal T cells of one
gain of function
mutation at position 538 in the mouse ortholog of the human isoform 3 of Carmil2 does not drive the development of T-
cell cancers. The inventors also show that this
mutation switches Carmil2 into an activated state which mimics the activated Carmil2 state resulting from physiological CD28 engagement. Therefore, the
gain of function
mutation can substitute for CD28 engagement and primes the NF-kB signalling pathway for cooperating with the TCR signalling pathway in normal T cells responding
in vivo to antigenic stimuli including tumor antigens. Once and only once the TCR has been engaged by an
antigen, including a
tumor antigen, it permits full
T cell activation in absence of co-
receptor CD28 engagement. Therefore,
rewriting the CD28 costimulatory pathway of CAR-T cells via the introduction of said
gain of function mutation in Carmil2 can induce long-lasting anti-tumor T responses in absence of inflammatory cues.