Immune Checkpoint Blockade in Cancer: A Review Article

Abstract

The human body has the ability to detect and neutralize malignant cells. However, tumors have developed mechanisms to evade immune defenses. In oncology, this phenomenon is known as immunoediting and it has three phases; Elimination, Equilibrium and escape, we will discuss these phases and the following topics in details; immunotherapy options, advantages and features of immunotherapy for cancer, disadvantages and limitations of immunotherapy and who is suitable for immunotherapy. It consists of three phases; Elimination , where specialized immune cells (T-lymphocytes and NK cells) identify and attack tumor structures; Equilibrium – surviving malignant cells enter a “dormant” state and Escape phase where the malignancy either suppresses the immune response through checkpoints or changes its genetic characteristics. Immunotherapy interrupts this process, restoring the body's "Immunoediting, through its phases of elimination, equilibrium, and escape, shapes tumor progression and determines the effectiveness of immune based therapies. Immune checkpoint inhibitors targeting CTLA 4 and PD 1/PD L1 have demonstrated significant antitumor activity, particularly in advanced and metastatic cancers, by restoring T cell function and overcoming tumor induced immune suppression. The integration of immunostimulants, monoclonal antibodies, cell therapies, and oncolytic viruses provide a versatile arsenal, enabling combination strategies that enhance efficacy and broaden indications. Immunotherapy offers distinct advantages over conventional treatments, including durable responses, targeted action, and efficacy against metastatic disease, though patient heterogeneity and tumor biology remain critical determinants of success. Limitations such as delayed therapeutic onset, immune related adverse events, restricted indications, and acquired resistance highlight the need for improved biomarkers and patient selection strategies. Future directions emphasize personalized immunotherapy, leveraging tumor microenvironment profiling, neoantigen discovery, and next generation checkpoint targets to refine patient suitability and maximize clinical benefit.