Immune cell engagers in solid tumors: promises and challenges of the next generation immunotherapy

In the landscape of cancer immunotherapy, immune cell engagers (ICEs) are rapidly emerging as a feasible and easy-to-deliver alternative to adoptive cell therapy for the antitumor redirection of immune effector cells. Even if in hematological malignancies this class of new therapeutics already hit the clinic, the development of ICEs in solid tumors still represents a challenge. Considering that ICEs are a rapidly expanding biotechnology in cancer therapy, we designed this review as a primer for clinicians, focusing on the major obstacles for the clinical implementation and the most translatable approaches proposed to overcome the limitations in solid tumors. •Immune cell engagers (ICEs) are molecules able to redirect immune effector cells against cancer cells.•ICEs can be used for the redirection of T cells, natural killer (NK) cells and cytotoxic/phagocytic cells.•ICEs have the potential for enabling a feasible and effective redirection of effector cells in patients with solid tumors.•ICEs design, antigen specificity and heterogeneity and immunosuppressive microenvironment are major issues in solid tumors.