Beyond youth: Understanding CAR T cell fitness in the context of immunological aging.

Population aging, a pervasive global demographic trend, is anticipated to challenge health and social systems worldwide. This phenomenon is due to medical advancements enabling longer lifespans, with 20% of the US population soon to be over 65 years old. Consequently, there will be a surge in age-related diseases. Senescence, characterized by the loss of biological maintenance and homeostasis at molecular and cellular levels, either correlates with or directly causes age-related phenotypic changes. Decline of the immune system is a critical factor in the senescence process, with cancer being a primary cause of death in elderly populations. Chimeric antigen receptor (CAR) T cell therapy, an innovative approach, has demonstrated success mainly in pediatric and young adult hematological malignancies but remains largely ineffective for diseases affecting older populations, such as late-in-life B cell malignancies and most solid tumor indications. This limitation arises because CAR T cell efficacy heavily relies on the fitness of the patient-derived starting T cell material. Numerous studies suggest that T cell senescence may be a key driver of CAR T cell deficiency. This review examines correlates and underlying factors associated with favorable CAR T cell outcomes and explores potential experimental and clinically actionable strategies for T cell rejuvenation.

Toward the development of true "off-the-shelf" synthetic T-cell immunotherapy.

Recent outstanding clinical results produced by engineered T cells, including chimeric antigen receptors, have already facilitated further research that broadens their applicability. One such direction is to explore new T cell sources for allogeneic "off-the-shelf" adoptive immunotherapy. Human pluripotent stem cells could serve as an alternative cell source for this purpose due to their unique features of infinite propagation ability and pluripotency. Here, we describe the current state of engineered T cell transfer with the focus on cell manufacturing processes and the potentials and challenges of induced pluripotent stem cell-derived T cells as a starting material to construct off-the-shelf T-cell banks.

Drug response to PD-1/PD-L1 blockade: based on biomarkers.

In recent years, immunotherapies targeting programmed death-1 (PD-1)/programmed death ligand 1 (PD-L1) have provided great hopes for patients with cancer. A successful anti-PD-1/PD-L1 therapy includes not only the elimination of immunosuppressive tumor cells but also the rejuvenation of exhausted T cells. Nevertheless, the efficacy of therapy is still low, so that biomarker-driven therapy has attracted more and more attention to identify patients who are likely to benefit from therapy and to reduce unnecessary disease progression. While many studies have focused on characteristics of tumor biopsies, biomarkers linked to T cell exhaustion and rejuvenation have just become new hot spots in drug response studies. However, no biomarker is perfect in drug response prediction currently, so there is an urgent need for other biomarkers to compensate for the deficiency. In this review, we summarize some approved and candidate biomarkers predictive of drug response before and during PD-1/PD-L1 blockade, including those characterizing responsive or suppressive tumor cells and those evaluating the T cell rejuvenation. Overall, we set up a comprehensive network of biomarkers of tumor characteristics and T cell rejuvenation, predicting drug response before and during anti-PD-1/PD-L1 therapies.