**1. Introduction**

To date, thousands upon thousands of people suffer and even die from various tumors with high morbidity and mortality including malignant hematologic tumors and metastatic solid tumors worldwide, which have cause tremendous physical and mental stress to the patients and their guardians [1–6]. Despite the encouraging progresses in cancer treatment, one of the core dilemmas is the current limitation in classical therapeutic modalities such as surgery, radiation and chemotherapy [7, 8]. For instance, surgery in combination with radiation treatment and chemotherapy drugs has been proved to be effective for localized cancers without metastasis and diffusion [9, 10]. Chemoradiotherapy has been considered as a synergistic anticancer remedy for locally advanced solid tumors whereas with increased damage to normal tissues and microbiota resistance [11–13]. Distinguish from the conventional cancer treatment (e.g., surgery, radiotherapy and chemotherapy), noncellular immunotherapy such as checkpoint

inhibitors (e.g., PD-1, PD-L1, CTLA4), lymphocyte-promoting cytokines (e.g., IFN-γ, GM-CSF, G-CSF), and cancer vaccines (e.g., mRNAs) has been continuously developed to fulfill the goals for cancer administration as well [14–17]. Additionally, current progress has also highlighted the feasibility of nanomaterials (e.g., organic nanomaterials, inorganic nanomaterials, organic–inorganic hybrid nanomaterials) as promising agents for cancer therapy based on the knowledge of nanobiotechnology and clinical biomedicine [18–20]. However, the significant disadvantages of the aforementioned strategies are apparent and should not be ignored including drug delivery barriers, graft-versushost disease, off-target effects and severe toxicity [5, 21, 22].

Therewith, the assumption of eradicating tumors by utilizing the human immune system has been successfully and extensively practiced for the past decades by pioneering investigators and clinicians [23]. To date, a series of cellular Immunotherapy has been identified to promote the outcomes and reduce adverse reactions of cancer patients, and in particular, those with late-stage patients with various treatment-refractory cancers [14–17]. Therefore, in this chapter, we mainly focus on the progress as well as the prospective and challenges in cellular immunotherapy for cancer treatment including the patient-specific immune cells (e.g., tumor infiltrating lymphocytes, cytokine induced killer cells), innate immunocytes (e.g., natural killer cells, dendritic cells, macrophage), adaptive immunocytes (T lymphocytes, B lymphocytes), engineered immunocytes (e.g., chimeric antigen receptor-transduced T cells, T cell receptor-transduced T cells, CAR-NK, CAR-M) [21, 24–27]. Collectively, the immune cell-mediated cancer immunotherapy has constituted a promising area of cancer biotherapy.
