Folate receptor α (FR) was discovered many decades ago, along with drugs that target intracellular folate metabolism, such as pemetrexed and methotrexate. Folate is taken up by the cell via this receptor, which also targeted by many cancer agents due to the over-expression of the receptor by cancer cells. FR is a membrane-bound glycosyl-phosphatidylinositol (GPI) anchor glycoprotein encoded by the folate receptor 1 (FOLR1) gene. FR plays a significant role in DNA synthesis, cell proliferation, DNA repair, and intracellular signaling, all of which are essential for tumorigenesis. FR is more prevalent in cancer cells compared to normal tissues, which makes it an excellent target for oncologic therapeutics. FRα is found in many cancer types, including ovarian cancer, non-small-cell lung cancer (NSCLC), and colon cancer. FR is widely used in antibody drug conjugates, small-molecule-drug conjugates, and chimeric antigen-receptor T cells. Current oncolytic therapeutics include mirvetuximab soravtansine, and ongoing clinical trials are underway to investigate chimeric antigen receptor T cells (CAR-T cells) and vaccines. Additionally, FRα has been used in a myriad of other applications, including as a tool in the identification of tumor types, and as a prognostic marker, as a surrogate of chemotherapy resistance. As such, FRα identification has become an essential part of precision medicine.

Claudins are a family of 27 proteins that have an important role in the formation of tight junctions. They also have an important function in ion exchange, cell mobility, and the epithelial-to-mesenchymal transition, the latter being very important in cancer invasion and metastasis. Therapeutic targeting of claudins has been investigated to improve cancer outcomes. Recent evidence shows improved outcomes when combining monoclonal antibodies against claudin 18.2 with chemotherapy for patients with gastroesophageal junction cancer. Currently, chimeric antigen receptor T-cells targeting claudin 18 are under investigation. In this review, we will discuss the major functions of claudins, their distribution in the normal as well as cancerous tissues, and their effect in cancer metastasis, with a special focus on the therapeutic targeting of claudins to improve cancer outcomes.

Bispecific antibodies (BsAbs) have shown potential in cancer treatment and have become a rapidly growing field in cancer immunotherapy. Unlike monoclonal antibodies with two identical binding sites, BsAbs simultaneously bind two distinct epitopes on the same or different antigens, allowing for a range of mechanisms of action, including engaging immune cells to kill cancer cells and blocking signaling pathways. Despite regulatory approvals for hematological malignancies in the last decade, their clinical success in solid malignancies has been lacking until recently. There are currently five BsAbs approved by the FDA in the United States for solid tumors—amivantamab, tarlatamab, tebentafusp, zanidatamab and zenocutuzumab—and two BsAbs approved in China—cadonilimab and ivonescimab. Currently, several BsAbs are under clinical development for solid tumors, but are mostly in early phase I and II trials. This review provides an overview of the basic mechanism of action of BsAbs, current FDA-approved BsAbs, and current BsAbs under clinical development, their challenges in clinical use, the management of toxicities, and future directions.

Claudins are a family of 27 proteins that have an important role in the formation of tight junc-tions. They also have an important function in ions exchange, cell mobility, and in in the epitheli-al-to-mesenchymal transition, the latter being very important in cancer invasion and metastasis. Therapeutic targeting of claudins has been investigated to improve cancer outcomes. Recent evi-dence shows improved outcomes when combining monoclonal antibodies against Claudin 18.2 with chemotherapy for patients with gastroesophageal junction cancer. Currently Chimeric anti-gen receptor T-cells targeting Claudin 18 are under investigation.