Adoptive cell therapy has emerged as a promising technique in the treatment of cancer, but suffers from bottlenecks such as the need for laborious ex vivo cell culturing. To circumvent ex vivo cell culturing, artificial antigen presenting cells (APCs) have been developed that consist of rigid microspheres to T cell activating signals are grafted. However, these APCs are stiffer than dendritic cells, which leads to suboptimal T cell activation. Semi-flexible polyisocyanopeptide polymers are decorated with T cell activating signals to provide less rigid APCs. My work focuses on optimizing polyisocyanopeptide based APCs towards their use in adoptive cell therapy.