Guidelines | Guidelines for the Clinical Application of Malignant Tumor Immunotherapy Technologies (Abridged Version)

Committee of Tumor Biotherapy, Chinese Anti-Cancer Association (CACA)

Abstract

Malignant tumors are one of the major diseases seriously threatening human health and life, with increasing incidence and mortality rates year by year, and have become the leading cause of death among Chinese residents. For a long time, surgery, radiotherapy, and chemotherapy have been the three conventional tumor treatment modalities, but their efficacy remains unsatisfactory for many tumors. With the evolution of tumor treatment concepts, immunotherapy has emerged as the fourth model of comprehensive tumor treatment and gained growing attention. Based on existing evidence-based medical evidence, combined with domestic and international guidelines and consensuses, the Chinese Anti-Cancer Association (CACA) has formulated these Guidelines for the Clinical Application of Malignant Tumor Immunotherapy Technologies, aiming to provide assistance to clinicians engaged in clinical immunotherapy.

Preface

Malignant tumors are one of the major threats to human health and life, with an increasing incidence rate annually. Experts from the World Health Organization (WHO) predict that by 2020, the global population will reach 8 billion, with 20 million new cancer cases and 12 million cancer-related deaths worldwide. Cancer will become a critical disease affecting human health and the largest global public health issue [1]. For a long time, surgery, radiotherapy, and chemotherapy have been the conventional tumor treatment methods, but many tumors cannot be cured by these approaches. With the rapid development of biotechnology and in-depth research on the mechanisms of tumor occurrence and progression, immunotherapy has become a new model of comprehensive tumor treatment.

Although this treatment model cannot yet replace traditional modalities, it has gained increasing recognition for improving the efficacy of surgery, radiotherapy, and chemotherapy, as well as prolonging patients' survival and enhancing their quality of life. Therefore, the Chinese Anti-Cancer Association (CACA) has organized experts in related fields to formulate these Guidelines for the Clinical Application of Malignant Tumor Immunotherapy Technologies based on existing evidence-based medical evidence and combined with domestic and international guidelines and consensuses, hoping to benefit clinicians engaged in clinical immunotherapy.

01 CAR-T Therapy Technology

1.1 Application of CAR-T Cells in Hematological Malignancies

1.1.1 Indications

General requirements: 1) Karnofsky Performance Status (KPS) score ≥ 50 or Eastern Cooperative Oncology Group Performance Status (ECOG PS) score ≤ 2. 2) Good cardiac, pulmonary, and hepatic function: left ventricular ejection fraction (LVEF) ≥ 50%; alanine transaminase (ALT, also known as GPT) and aspartate transaminase (AST, also known as GOT) < 3 times the normal upper limit; bilirubin < 2.0 mg/dL; oxygen saturation ≥ 92% in room air. 3) No active infection. 4) Expected survival > 12 weeks. 5) Positive expression of corresponding tumor cell targets detected by immunohistochemistry or flow cytometry. Naxcelen (CD19 chimeric antigen receptor T cell, CAR-T) can be used for relapsed and refractory adult acute lymphoblastic leukemia; Iciglen (BCMA CAR-T) can be used for the treatment of adult patients with relapsed or refractory multiple myeloma who have received at least three lines of prior therapy (including at least one proteasome inhibitor and one immunomodulatory drug); Zevorlen (BCMA CAR-T) can be used for the treatment of adult patients with relapsed/refractory multiple myeloma who have progressed after at least 3 prior lines of therapy (including proteasome inhibitors and immunomodulatory drugs) [2].

1.1.2 Operational Procedures

1).Lymphocyte collection: Generally, patients are required to have a platelet count > 50×10⁹/L, and donors a hemoglobin level > 60 g/L. The total number of mononuclear cells collected should be > 10⁹, and the lymphocyte collection volume is generally 60～600×10⁶/kg to ensure sufficient T cell raw materials [3]. Previous treatment drugs received by patients may affect CAR-T cell activity, and a certain washout period is required before T cell collection for different treatments or drugs.

2).Lymphodepletion: The commonly used lymphodepletion regimen is cyclophosphamide combined with fludarabine. It is recommended to adopt the lymphodepletion regimen of fludarabine (25～30 mg/m²/d for 3 consecutive days) combined with cyclophosphamide (250～500 mg/m²/d for 3～5 consecutive days) [4].

3).CAR-T cell infusion: CAR-T cells are generally infused 48 hours after lymphodepletion, with a maximum delay not exceeding 7 days. The conventional infusion dose is 1×10⁶ CAR-positive T cells/kg, and the recommended total infusion dose is > 2.5×10⁷ CAR-positive T cells [5]. Before cell infusion, acetaminophen and diphenhydramine or other H1-antihistamines can be optionally used for premedication to prevent hypersensitivity reactions (it is recommended to administer anti-allergic drugs 0.5～1.0 hours in advance).

1.1.3 Efficacy Evaluation

It is recommended to complete bone marrow cytology testing for efficacy evaluation 28 days after CAR-T cell infusion or after hematological recovery. For patients with extramedullary lesions, it is recommended to evaluate extramedullary lesions simultaneously 28 days after CAR-T treatment; MRI, CT, or X-ray can be used as evaluation methods, and PET-CT evaluation can be considered 3 months later. Efficacy evaluation is recommended monthly within 6 months.

1.1.4 Salvage Therapy After Relapse or Progression

For acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), the current most evidence-based method for relapse prevention is direct bridging to allogeneic hematopoietic stem cell transplantation (allo-HSCT). Sequential infusion of CAR-T cells targeting different antigens or dual-target CAR-T can further reduce the relapse rate. For relapse after CAR-T therapy, second CAR-T cell therapy is also worthy of clinical trial, and participation in other clinical studies can also be considered.

1.2 Application of CAR-T Cells in Lymphomas

1.2.1 Diffuse Large B-Cell Lymphoma

Currently, the indication for CAR-T therapy in China is adult patients with diffuse large B-cell lymphoma (LBCL) who have received at least two lines of systemic therapy. Adult LBCL patients with primary resistance to standard first-line immunochemotherapy or relapse within 12 months after first-line immunochemotherapy may be considered for CAR-T therapy. Axi-cel (axicabtagene ciloleucel) can be safely and effectively used in adult high-risk LBCL patients with positive PET evaluation after 2 courses of first-line standard immunochemotherapy [6].

1.2.2 Follicular Lymphoma and Marginal Zone Lymphoma

CAR-T therapy has shown excellent efficacy and good safety in patients with relapsed/refractory (R/R) follicular lymphoma (FL) and marginal zone lymphomas (MZL), which can significantly improve the prognosis and survival of such patients. Currently, regorafenib injection has been officially approved for the treatment of R/R FL.

1.2.3 Mantle Cell Lymphoma

Autologous hematopoietic stem cell transplantation (auto-HSCT) is the preferred standard treatment for transplant-eligible patients; for R/R mantle cell lymphoma (MCL) patients who have failed or are intolerant to at least one Bruton's tyrosine kinase (BTK) inhibitor, CAR-T cell therapy is preferred; if CAR-T cell therapy fails or is not feasible, allo-HSCT is recommended.

1.2.4 Chronic Lymphocytic Leukemia

For chronic lymphocytic leukemia (CLL) patients who relapse after allo-HSCT, donor-derived CAR-T cells can be considered, which can not only overcome the functional defects of patient-derived CAR-T cells but also achieve tumor control effects similar to donor lymphocyte infusion, and no severe graft-versus-host disease (GVHD) has been observed in small-sample clinical observations [7]. Allogeneic CAR-NK cells derived from umbilical cord blood have shown good efficacy and safety in CLL in recent clinical studies. To overcome tumor antigen escape after CAR-T therapy, CD19/CD20 dual-target CAR-T cell therapy can be attempted. However, the current clinical trial data of these treatment strategies in CLL are limited, and their effectiveness needs to be confirmed by larger samples.

1.2.5 Hodgkin's Lymphoma

Immune checkpoint inhibitors, brentuximab vedotin, hematopoietic stem cell transplantation, and conventional chemotherapeutic drugs remain common choices for the clinical treatment of R/R Hodgkin's lymphoma (HL). Currently, the clinical research results of CD30-targeted CAR-T are not satisfactory, but with in-depth research and exploration of combined therapy, it is believed that CAR-T will still have a role in R/R HL in the future.

1.2.6 T-Cell Lymphoma

The treatment of relapsed and refractory T-cell lymphoma (TCL) is still dominated by chemotherapy, targeted therapy, and hematopoietic stem cell transplantation. CAR-T cell clinical trials are still in the preliminary stage. With the in-depth understanding of immune mechanisms and the maturity of gene editing technology, more specific targets will be identified, CAR-T cell preparation platforms will be improved, and more efficient and safer CAR-T cells will be designed. It is believed that CAR-T cell immunotherapy will achieve more breakthroughs and developments in the future.

1.3 Application of CAR-T Cells in Solid Tumors

1.3.1 Claudin18.2 CAR-T

Claudin (CLDN) proteins are a family of transmembrane tight junction proteins. CLDN18.1 is selectively expressed in normal lung epithelium, while CLDN18.2 is only expressed in gastric epithelial cells. Studies have shown that CLDN18.2 is highly expressed in tumors such as gastric cancer and pancreatic cancer. Based on its expression characteristics in tumors, CLDN18.2 may be a potential target for the treatment of solid tumors such as gastric cancer and pancreatic cancer [8].

Currently, more than 20 cell therapy products targeting CLDN18.2 are in preclinical or early clinical research stages, and the humanized second-generation autologous CAR-T cell targeting CLDN18.2 (CT041) has entered the pivotal Phase II clinical research stage. The indications currently being explored in clinical stages are mainly advanced digestive system tumors, such as gastric cancer and pancreatic cancer. The main CLDN18.2-targeted CAR-T product with disclosed clinical data is CT041, which is the world's first CLDN18.2-targeted cell therapy product to enter confirmatory Phase II clinical trials [9].

1.3.2 Mesothelin CAR-T

The mesothelin (MSLN) gene encodes a precursor protein, which is hydrolyzed to produce mesothelin—a cell surface glycoprotein anchored to the cell membrane via glycosylphosphatidylinositol (GPI). MSLN directly activates or interacts with its receptor CA125/MUC16 to activate nuclear factor κB (NF-κB), phosphatidylinositol 3-kinase (PI3K), and mitogen-activated protein kinase (MAPK) signaling pathways, promoting tumor cell proliferation, local invasion, metastasis, and anti-apoptosis, thereby achieving malignant transformation and invasiveness of tumors.

Currently, about 20 CAR-T cell therapy studies targeting MSLN for solid tumors have entered clinical research stages, mainly focusing on Phase I/II, with no studies progressing to Phase III or marketed drugs [10]. The clinical research indications are mostly mesothelioma, pancreatic cancer, and ovarian cancer, as well as cholangiocarcinoma, lung cancer, and breast cancer. The drug use models in clinical research include single-agent exploration or combined with immune checkpoint signal regulation, and the administration methods are intravenous injection or local injection (pleural cavity injection, intraperitoneal injection, etc.). Some studies adopt lymphodepletion, while others explore non-lymphodepletion. Overall, MSLN-targeted CAR-T cell therapy for solid tumors has been clinically verified to have good safety and preliminary efficacy observed in clinical practice, but further research is needed.

1.3.3 Guanylyl Cyclase C CAR-T

Guanylyl cyclase C (GCC/GUCY2C) is a member of the receptor guanylyl cyclase family and plays a key role in gastrointestinal fluid and ion homeostasis. Recent studies have found that GUCY2C is stably expressed in primary colorectal cancer cells and abnormally highly expressed in metastatic colorectal cancer cells, making it one of the specific marker molecules for metastatic colorectal cancer [11].

Currently, about 10 CAR-T cell therapy studies targeting GUCY2C for solid tumors have entered clinical research stages, mainly focusing on Phase I/II, with no studies progressing to Phase III or marketed drugs. The main clinical research indication is colorectal cancer.

1.3.4 Epithelial Cell Adhesion Molecule CAR-T

Epithelial cell adhesion molecule (EpCAM) is a glycosylated type I transmembrane glycoprotein involved in regulating cancer cell adhesion, proliferation, migration, stemness, and epithelial-mesenchymal transition (EMT). In tumor tissues, EpCAM expression changes from the basal layer to uniform expression on the cell membrane surface, enabling it to serve as a target in cellular or antibody therapies.

Currently, multiple cell therapy products targeting EpCAM are in preclinical or early clinical research stages, but no product has entered the pivotal clinical stage or applied for marketing. The indications currently being explored in clinical stages are mainly advanced digestive system tumors, such as gastric cancer and colorectal cancer [12].

1.3.5 Glypican 3 CAR-T

Glypican 3 (GPC3) plays an important role in regulating cell growth and differentiation and is closely related to the occurrence and development of liver cancer.

Currently, multiple cell therapy products targeting GPC3 are in preclinical or early clinical research stages, but no product has entered the pivotal clinical stage or applied for marketing. The indications explored in clinical stages are mainly hepatocellular carcinoma, as well as liposarcoma, lung cancer, Merkel cell carcinoma, rhabdomyosarcoma, Wilms tumor, cholangiocarcinoma, yolk sac tumor, etc.

1.3.6 Receptor Tyrosine Kinase-Like Orphan Receptor 1 CAR-T

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a member of the ROR receptor family. ROR1 can mediate signal transduction of non-canonical Wnt pathways and play important roles in various physiological processes. As a receptor for Wnt5a, ROR1 is involved in activating the NF-κB pathway in tumor cells. ROR1 is lowly expressed or not expressed in normal human tissues but highly expressed in various malignant tumors or tissues.

Currently, multiple cell therapy products targeting ROR1 are in preclinical or early clinical research stages, but no product has entered the pivotal clinical stage or applied for marketing. The indications mainly include ROR1-positive hematological tumors and solid tumors, including non-small cell lung cancer (NSCLC), triple-negative breast cancer, CLL, MCL, and ALL [13].

02 Application of T Cell Receptor-Modified T Cell (TCR-T) Therapy Technology in Solid Tumors

T cell receptor-modified T cell (TCR-T) therapy has shown unique advantages in solid tumors, with tumor tropism and targeting. Currently, there are more than 200 TCR-T cell clinical trials worldwide mainly targeting solid tumors, the most common being malignant melanoma, sarcoma, digestive system malignant tumors, lung cancer, etc.

2.1 Selection of Patients and Targets

2.1.1 Pre-Treatment Evaluation of Patients

In clinical studies, adults over 18 years old are usually selected, with the maximum age generally not exceeding 80 years old. Patients with a confirmed diagnosis of malignant tumor who have failed or are intolerant to second-line therapy are usually selected. Patients with an ECOG score of 0～1 are often included.

2.1.2 Selection of Targets

Currently, the main targets for TCR-T cell therapy are cancer-testis antigen families such as NY-ESO-1, MAGE-A3, MAGE-A4, as well as tumor-overexpressed antigens such as CEA and tumor-specific antigens such as HPV and HBV antigens [13]. HLA-restricted specific TCR sequences have been previously identified for target antigens. Patients' HLA typing can be confirmed by peripheral blood flow cytometry or PCR technology, and patients with matching HLA and targets can be selected to prepare personalized TCR-T cells [14].

2.2 Clinical Treatment Process of TCR-T Cells

2.2.1 Lymphocyte Isolation

Typically, the total number of lymphocytes collected by apheresis is about 2～5×10⁹. The apheresis parameters are appropriately adjusted according to the requirements of different trials and the absolute counts of white blood cells and lymphocytes in patients: 600 mL of blood per cycle, 6～8 mL of cell suspension collected per cycle, 10～15 cycles, with a total circulating blood volume of about 6,000～9,000 mL, and a total collected cell suspension of generally about 80～100 mL. Attention should be paid to the drug washout period [15].

2.2.2 Chemotherapy Lymphodepletion

The commonly used lymphodepletion regimen is fludarabine injection (25～40 mg/m²/d for 3～4 consecutive days) and cyclophosphamide injection (300～500 mg/m²/d for 2～3 consecutive days).

2.2.3 TCR-T Cell Infusion

Before TCR-T cell reinfusion, the patient's clinical status should be re-evaluated, including body temperature, heart rate, blood pressure, oxygenation status, presence of active infection, and severe organ dysfunction. Antipyretics, analgesics, and antihistamines are often administered before TCR-T cell infusion to reduce infusion reactions during reinfusion. During reinfusion, the patient's vital signs should be closely monitored, and tocilizumab injection should be available for the management of related side effects if necessary. As a key cytokine for stimulating T cell proliferation in vivo, IL-2 can be administered within 24 hours after TCR-T cell infusion. The recommended dose abroad is 500,000～720,000 IU/kg every 8 hours for 15 consecutive doses, but the dosage and frequency can be adjusted according to the patient's specific tolerance.

2.3 Evaluation of Laboratory Indicators

In addition to imaging evaluation, monitoring of laboratory indicators after TCR-T cell therapy is of great significance for predicting adverse events and evaluating efficacy. In synovial sarcoma patients receiving TCR-T cell therapy, the number of TCR-T cells and the proportion of effective memory subsets are significantly increased in responding patients, and cytokines such as IL-15, IFN-γ, and IL-6 are elevated on days 3 and 4 after reinfusion, which are positively correlated with efficacy [16]. In pancreatic cancer, in addition to cell numbers, IFN-γ, CCL4, GM-CSF, and TNF are significantly elevated in the peripheral blood of patients with effective treatment. In HPV-related tumors, after patients receive TCR-T cell therapy, cytokines IFN-γ, TNF-α, IL-2, and VEGFA are significantly elevated in responding patients [17].

03 Application of Tumor-Infiltrating Lymphocytes (TIL) in Solid Tumors

3.1 TIL Therapy for Malignant Melanoma

3.1.1 Lymphodepletion Regimen for TIL Therapy in Malignant Melanoma

Lymphodepletion before tumor-infiltrating lymphocyte (TIL) infusion is an important part of TIL therapy. Commonly used lymphodepletion regimens include cyclophosphamide + fludarabine, fludarabine + radiotherapy, or cyclophosphamide + fludarabine + radiotherapy [18].

3.1.2 Role of IL-2 in TIL Therapy

For patients with metastatic melanoma who have failed first-line and second-line therapies, combined treatment with IL-2 and TIL can improve TIL growth and activity, thereby increasing the clinical response rate [19].

3.2 TIL Therapy for Other Solid Tumors

Currently, the main tumor type treated with TIL is malignant melanoma, followed by NSCLC, ovarian cancer, and head and neck cancer. TIL has shown good clinical efficacy in metastatic melanoma and advanced cervical cancer, and preliminary efficacy in NSCLC, colorectal cancer, and breast cancer [20]. Due to the heterogeneity of tumor antigen mutations, the response of TIL cells to solid tumors varies. Compared with TIL from malignant melanoma, TIL from other tumors have weaker reactivity and lower function.

3.3 Combined Application of TIL with Other Therapies

3.3.1 Combination of TIL with Immune Checkpoint Inhibitors

Immune checkpoint receptors (such as CTLA-4 and PD-1/PD-L1) are expressed on the surface of T cells and serve as self-protection mechanisms of the immune system. In tumor patients, CTLA-4 and PD-1 molecules on effector T cells are upregulated and bind to B7-1/B7-2 on antigen-presenting cells or PD-L1 on tumor cells, respectively, leading to suppressed T cell function [21]. In addition, after long-term exposure of T cells to tumor antigens, CD8+ T cells may undergo apoptosis or enter an abnormal differentiation state, with high expression of inhibitory receptors, making CD8+ T cells almost unresponsive to specific tumor antigens. At this time, checkpoint inhibitors can be used to improve CD8+ T cell activity [22]. Therefore, to increase TIL tumor reactivity, immune checkpoint inhibitor (ICI) therapy can be combined during the initial culture stage of TIL and after TIL infusion.

3.3.2 Combination of TIL with BRAF Inhibitors

Most tumor patients have BRAF mutations. Activated BRAF mutations (mainly V600E) can induce immune escape, make the body's immunity "blunt," and gain the ability to evade T cell immune responses. The BRAF inhibitor vemurafenib can reduce related immunosuppressive signals, decrease immunosuppressive cells, enhance melanoma antigen expression, and promote lymphocyte infiltration and specific T cell proliferation. However, the clinical effect duration of BRAF inhibitors is short. A recent clinical trial showed that 7 out of 11 patients with metastatic melanoma who received combined treatment with TIL, high-dose IL-2, and vemurafenib achieved a response, of which 2 patients achieved complete remission [23].

3.3.3 Combination of TIL with Other Therapies

Dendritic cells (DC) are the most potent antigen-presenting cells in the human body. DC therapy involves culturing and inducing DC from patients' autologous monocytes in vitro, then loading them with corresponding tumor antigens to prepare tumor antigen-loaded DC, which are then injected into the body to stimulate the proliferation of tumor-killing lymphocytes in vivo, exert long-term tumor surveillance and tumor-killing effects, and achieve the goal of controlling and eliminating tumors. DC vaccines can be combined with TIL therapy to activate and increase the number of TIL, and clinical trials of combined DC and TIL therapy are currently underway [24]. Oncolytic viruses can improve the tumor control effect of TIL by inducing TIL to secrete cytokines, and the combined therapy of TIL and oncolytic viruses is also being explored [25].

04 Application of Cytokine-Induced Killer (CIK) Cells in Tumors

Cytokine-induced killer (CIK) cell therapy has been widely used in tumor immunotherapy due to the easy availability of cell sources and strong tumor control activity. CIK therapy is often combined with other treatment modalities, such as radiotherapy and chemotherapy, radiofrequency ablation, and immune checkpoint inhibitor therapy. Radiotherapy and chemotherapy, as well as radiofrequency ablation, can induce stable tumor-specific T cell responses, further enhancing tumor-specific immune responses. Immune checkpoint inhibitor therapy can effectively break the inhibitory tumor microenvironment. Combined application of CIK cells can effectively inhibit tumor cell growth and even kill tumors, and the anti-tumor effect of CIK cells has no significant toxic side effects on the body. When tumor-specific antigens cannot be determined or relatively little is known about the antigens, the application of CIK cells as adjuvant therapy after tumor radiotherapy, chemotherapy, and surgery is of great significance.

4.1 Multiple Myeloma

The bortezomib + dexamethasone + thalidomide (BDT) regimen is one of the most commonly used chemotherapeutic regimens for the treatment of multiple myeloma (MM) patients. DC has high antigen recognition and presentation capabilities, and the combination of CIK cells with DC has been proven to have good tumor control effects in preclinical and clinical practice. A meta-analysis showed that compared with the BDT regimen alone, patients receiving the DC-CIK adoptive immunotherapy combined with BDT regimen had a significantly higher disease remission rate, and the levels of CD4+ and CD4+/CD8+ in serum also increased significantly. DC-CIK adoptive immunotherapy combined with BDT treatment for MM patients can improve immune function and quality of life.

4.2 Leukemia

Since the immune system plays an important role in monitoring and killing tumor cells, when chemotherapy and bone marrow transplantation are ineffective for leukemia patients, immune cell therapy (such as CIK cells) has achieved certain efficacy as an alternative therapy. Currently, CIK therapy as a supplement to chemotherapy or hematopoietic stem cell transplantation (HSCT) has been used in clinical research. Studies have shown that the combination of CIK and DC cells for the treatment of leukemia has fewer adverse reactions and mild complications, and is a safe and effective method for the treatment of relapsed acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation [26].

4.3 Lymphoma

There are relatively few clinical studies on CIK therapy for lymphoma. Studies have reported that a patient with relapsed and refractory follicular lymphoma failed to achieve effective remission after multiple chemotherapy treatments, and after allogeneic CIK cell infusion therapy, the patient achieved long-term complete remission, accompanied by improved symptoms and prolonged survival [27]. Clinical studies on DC-CIK cell therapy for diffuse large B-cell lymphoma also suggest that this therapy can increase the absolute count of peripheral blood lymphocytes in patients, improve cellular immune function, and enhance quality of life [28].

4.4 Esophageal Cancer

Compared with chemotherapy alone, CIK/DC-CIK cell combined with chemotherapy can enhance the immune function of esophageal cancer (EC) patients and thereby improve efficacy. In elderly EC patients, the short-term efficacy of DC-CIK cell combined with intensity-modulated radiation therapy (IMRT) is superior to IMRT alone, and the quality of life and survival period are significantly improved. The latest study shows that in early esophageal squamous cell carcinoma, the overall survival and progression-free survival of the CIK cell group are significantly higher than those of the control group [29].

4.5 Liver Cancer

The application of CIK cell therapy after liver cancer surgery reduces the postoperative recurrence rate of patients, prolongs the time to first recurrence after CIK cell therapy, and has no serious adverse reactions [30].

4.6 Pancreatic Cancer

S-1 is an oral drug composed of tegafur (FT), gimeracil (CDHP), and oteracil potassium (Oxo) in a molar ratio of 1.0∶0.4∶1.0. Studies have shown that compared with the S-1 monotherapy group, S-1 combined with CIK cell therapy can significantly reduce serum CA-199 levels, and the incidence of non-hematological toxicity, fatigue, and non-infectious fever is significantly reduced. In the second-line treatment of gemcitabine-refractory advanced pancreatic cancer patients, the S-1 combined with CIK regimen is well-tolerated [31]. Another Phase II clinical trial in gemcitabine-refractory advanced pancreatic cancer patients also found that CIK cell therapy can effectively improve patients' quality of life [32].

4.7 Gastrointestinal Tumors

Studies have shown that CIK/DC-CIK cell combined with chemotherapy can significantly prolong the overall survival and progression-free survival of patients with advanced gastrointestinal tumors, improve quality of life, and have no serious adverse reactions, suggesting that CIK/DC-CIK cell combined with chemotherapy is safe and a feasible option for extending survival and improving quality of life in patients with advanced gastrointestinal tumors [33-35].

4.8 Renal Cancer

Studies have shown that the combined application of anti-PD-1 and CIK cell therapy is safe and effective for metastatic clear cell renal cell carcinoma (mRCC) patients who have failed previous targeted therapy. Even after long-term drug withdrawal, there is a high CR rate and long-term DFS [36]. Immunotherapy with autologous tumor lysate-pulsed dendritic cells and cytokine-induced killer cells (Ag-DC-CIK) reduces the risk of disease progression and recurrence in postoperative RCC patients [37].

4.9 Bladder Cancer

After DC-CIK therapy, bladder cancer patients show restored T cell phenotype ratio, increased diversity of TCR repertoire, reduced ctDNA, and prolonged recurrence-free survival [38].

4.10 Lung Cancer

Treatment of advanced non-small cell lung cancer patients with programmed death 1 (PD-1) blocking antibodies pembrolizumab or nivolumab with or without autologous CIK cell infusion: combined therapy significantly increases CD3+CD56+CD16+ T cells, while PD-1 blocking antibody alone significantly increases myeloid-derived suppressor cells. Although serum IL-4 levels are downregulated after combination, IFN-γ levels remain unchanged, indicating that the PD-1 monoclonal antibody combined with CIK therapy regimen is safe and effective [39-40].

4.11 Breast Cancer

DC-CIK combined with chemotherapy can significantly improve the CR, PR, and ORR of breast cancer patients, but there is no significant difference in safety. There is no difference in the incidence of leukopenia, thrombocytopenia, alopecia, nausea/vomiting, liver complications, and neurological complications between breast cancer patients receiving DC-CIK combined with chemotherapy and those receiving chemotherapy alone [41].

4.12 Nasopharyngeal Cancer

The combined application of CIK cells with camrelizumab (PD-1 monoclonal antibody) (CIK + camrelizumab + anlotinib) significantly improves patients' immune indicators, reduces recurrence and metastasis rates, and results in a higher 2-year survival rate [42]. This indicates that CIK cells have a strong anti-tumor effect, and by effectively killing tumor cells, enhancing immune function, and forming a synergistic effect with other treatment modalities, they can improve patient prognosis.

05 Natural Killer (NK) Cell Therapy Technology

5.1 Application of NK Cells in Hematological Malignancies

5.1.1 Application of NK Cells in Hematopoietic Stem Cell Transplantation

Infusion of haploidentical natural killer (NK) cells into AML patients who did not undergo HCT after non-myeloablative chemotherapy resulted in donor NK cell expansion and induction of complete hematological remission in some patients, indicating that haploidentical NK cells can survive and proliferate in patients and can be used alone or as an adjuvant therapy for HCT [43].

Donor NK cell-mediated alloreactivity can kill tumor cells through the graft-versus-leukemia (GVL) effect, promote transplantation by ablating recipient T cells, and prevent GVHD by consuming recipient antigen-presenting cells and producing IL-10 [44]. Therefore, NK cell infusion before HCT is safe and feasible, and NK cell transfer can also serve as a bridge to HCT, helping to reduce the disease burden and making patients eligible for HCT.

5.1.2 Application of NK Cells in Non-Hematopoietic Stem Cell Transplantation

Due to the limitations of HCT that prevent it from being applicable to all patients, NK cells can also be used alone in hematological malignancies. Allogeneic NK cell adoptive reinfusion combined with chemotherapy helps to further relieve AML patients, reduce minimal residual disease, and lower the long-term recurrence rate.

5.1.3 Application of CAR-NK Cells in Hematological Malignancies

Currently, there are relatively few clinical studies on the application of CAR-NK cells for treatment. In a Phase I/II clinical study, tumor control responses occurred rapidly within 30 days after CAR-NK cell injection, and CAR-NK cells persisted at low levels in patients for at least 12 months after reinfusion [45].

5.2 Application of NK Cells in Solid Tumors

5.2.1 Clinical Application of Conventionally Cultured NK Cells

In clinical studies of allogeneic NK cells combined with chemotherapy + anti-GD2 monoclonal antibody in children with relapsed/refractory neuroblastoma, allogeneic NK cell therapy combined with anti-GD2 monoclonal antibody has strong safety, and NK cells have better anti-neuroblastoma activity at higher doses, showing good clinical application potential, but further confirmation is needed [46].

5.2.2 Clinical Application Based on NK Cell Lines

Based on the characteristics of easy culture and expansion of the NK-92 cell line, some researchers have also applied it to the clinical treatment of refractory and drug-resistant tumors. In dose-escalation trials, all patients tolerated the reinfusion dose without serious adverse reactions, and 3 patients with advanced drug-resistant lung cancer achieved tumor control responses and clearance of tumor metastases.

5.2.3 Clinical Application of CAR-NK in Solid Tumors

In clinical studies of CAR-NK cell therapy for solid tumors, the extracellular domain of the NK cell receptor NKG2D is fused with DAP12, and CAR is constructed by RNA electroporation to improve NK cell tumor response and reduce clinical application risks. In clinical studies of NK cell therapy for solid tumors, NK cell therapy has good safety, and preliminary results suggest that the treatment effect may be related to the cell dose. Currently, clinical applications include refractory and metastatic lung cancer, liver cancer, renal cancer, and colorectal cancer [47].

There are no economic conflicts of interest that affect the scientificity and credibility of this article.