In cancer treatment, the first-generation, cytotoxic drugs, though effective against cancer cells, also harmed healthy ones. The second-generation targeted cancer cells precisely to inhibit their growth. Enter the third-generation, consisting of immuno-oncology drugs, designed to combat drug resistance and bolster the immune system’s defenses. These advanced therapies operate by obstructing the uncontrolled growth and spread of cancer cells through the body, ultimately eliminating them effectively. Within the arsenal of cancer treatment, monoclonal antibodies offer several advantages, including inducing cancer cell apoptosis, precise targeting, prolonged presence in the body, and minimal side effects. A recent development in cancer therapy is Antibody-Drug Conjugates (ADCs), initially developed in the mid-20th century. The second generation of ADCs addressed this issue through innovative antibody modification techniques, such as DAR regulation, amino acid substitutions, incorporation of non-natural amino acids, and enzymatic drug attachment. Currently, a third generation of ADCs is in development. This study presents an overview of 12 available ADCs, reviews 71 recent research papers, and analyzes 128 clinical trial reports. The overarching objective is to gain insights into the prevailing trends in ADC research and development, with a particular focus on emerging frontiers like potential targets, linkers, and drug payloads within the realm of cancer treatment.

Monoclonal antibodies (mAbs) represent one of the most successful classes of biopharmaceuticals, with more than 100 approved for treating oncological, immunological, and infectious diseases. Antibody discovery and development have been driven by diverse methodologies. Classical strategies such as mouse hybridoma technology, phage display, transgenic mouse models, and single B cell isolation have enabled the generation of high-affinity therapeutic antibodies. Beyond binding affinity, recent innovations in combinatorial antibody libraries have facilitated the selection of functional antibodies within cellular environments, revealing their ability to act as agonists or antagonists and influence signal transduction pathways. These insights expand therapeutic applications by enabling modulation of complex cellular responses. Recent breakthroughs in artificial intelligence, involving antibody generation supported by rapidly growing antibody sequence and structure databases, are transforming computational protein design. This review highlights five major approaches (hybridoma technology, phage display, transgenic mouse models, and single B cell isolation, de novo antibody design) for antibody discovery and development. These approaches offer innovative strategies designed to accelerate the discovery process and enhance therapeutic outcomes for human diseases.

HER2 overexpression is associated with aggressive and poor patient outcome. HER2 has become a crucial target in cancer treatment, and the discovery of effective HER2-targeted therapies marked a significant milestone in treating HER2-positive cancers. This led to the approval of trastuzumab, the first HER2-targeted monoclonal antibody. Later, trastuzumab was used to develop antibody-drug conjugates (ADCs) for breast cancer, which have shown promising results. ADCs are combined trastuzumab with a cytotoxic drug to improve effectiveness while reducing side effects. Two ADCs, trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd), have been approved by the FDA for treating HER2-positive breast cancer. However, drug resistance has become a serious issue, reducing the long-term success of these treatments. This review explores key mechanisms of ADCs resistance including alteration in HER2 expression, antibody and payload-related resistance, altered cell signaling, impaired lysosomal and intracellular activity, and tumor microenvironment. By analyzing recent studies in ADCs resistance, this review provides an insight into ADC resistance mechanisms and potential strategies for improving therapeutic outcomes HER2 positive breast cancer.

Although breast cancer treatment has evolved significantly in recent years, drug resistance remains a major challenge. To identify new targets for breast cancer, we found that stage-specific embryonic antigen 4 (SSEA-4) is expressed in all subtypes of breast cancer cell lines, and the increased expression of the associated enzymes β3GalT5 and ST3Gal2 correlates with poor recurrence-free survival (RFS) in breast cancer. We also found that SSEA-4 antibodies can be rapidly internalized into breast cancer cells, a property that makes SSEA-4 an attractive target for antibody-drug conjugates (ADCs). Furthermore, the SSEA-4 antibody conjugated to the anticancer agents showed efficacy against SSEA-4-positive breast cancer cells, including those resistant to PARP inhibitor, trastuzumab, and CDK7 inhibitor. In addition, SSEA-4 ADCs showed no efficacy in β3GalT5-knockout MDA-MB-231 cells, highlighting the essential role of SSEA-4 as the target antigen for ADCs activity. Our work shows that SSEA-4-ADCs could be a therapeutic option for breast cancers.

Cell cycle arrest and programmed cell death are crucial biological processes in cancer development. Regulating cell fate decisions is essential due to their potential to induce cell cycle arrest and cell death. Inducing cell cycle regulatory proteins in tumor cells is considered a key objective in cancer therapy. Here, we present a novel method that selects antibodies from an antibody library to inhibit cancer growth using fluorescence‐activated cell sorting (FACS) assays and cell cycle analysis. This approach seeks antibodies that induce cancer cells to enter the G0 or G1 phase, a quiescent state where cells cease to proliferate and trigger programmed cell death. We found that the T1 antibody effectively suppresses the proliferation of cancer cells. Mechanistically, serine protease 3 (PRSS3) is a target antigen of the T1 antibody. We demonstrated that PRSS3 controls tumor cell proliferation and apoptosis through interaction with the T1 antibody. This research suggests that PRSS3 holds great potential as a target for solid cancer treatment. This cycle‐based approach to antibody screening shows potential because it can be broadly applied to cancer and other challenging diseases.