A targeted T-cell engaging agent for treating a condition characterized by the presence of unwanted cells includes (a) a targeting moiety that is capable of targeting the unwanted cells (b) a first T-cell engaging domain capable of T-cell engaging activity when binding a second T-cell engaging domain, wherein the second T-cell engaging domain is not part of the agent (c) at least one inert binding partner capable of binding to the first T-cell engaging domain such that the first T-cell engaging domain does not bind to the second T-cell engaging domain unless the inert binding partner is removed and (d) at least one cleavage site separating the first T-cell engaging domain and the inert binding partner, wherein the cleavage site is: (i) cleaved by an enzyme expressed by the unwanted cells (ii) cleaved through a pH-sensitive cleavage reaction inside the unwanted cell (iii) cleaved by a complement-dependent cleavage reaction or (iv) cleaved by a protease that is colocalized to the unwanted cell by a targeting moiety that is the same or different from the targeting moiety in the agent.La présente invention concerne un agent dactivation de lymphocytes T ciblé pour traiter une affection caractérisée par la présence de cellules indésirables qui comprend (a) un fragment de ciblage qui est capable de cibler les cellules indésirables (b) un premier domaine dactivation de lymphocyte T capable de déclencher lactivité de lymphocytes T lors de la liaison dun deuxième domaine dactivation de lymphocytes T, le deuxième domaine dactivation de lymphocytes T ne faisant pas partie de lagent (c) au moins un partenaire de liaison inerte capable de se lier au premier domaine dactivation de lymphocytes T de sorte que le premier domaine dactivation de lymphocytes T ne se lie pas au deuxième domaine dactivation de lymphocytes T sauf si le partenaire de liaison inerte est enlevé et (d) au moins un site de clivage séparant le premier domaine domaine dactivation de lymphocytes T et le partena
