Knock-ins, knockdowns and/or overexpression are other ways to improve activity. For example, in this, knockdown enhanced CD8+ and CD4+ T-cell accumulation in the tumour, increased proliferation and increased cytokine production https://www.nature.com/articles/nature12988
For example, in this the authors showed that SOCS1-inactivation improved the intrinsic and extrinsic antitumour effect of adoptively transferred CD4+ T-cells. In addition, inactivation not only restored CD4+ T-cell expansion but it boosted CD8+ T-cell efficacy as well https://www.science.org/doi/10.1126/sciimmunol.abe8219