Platinum-based anticancer drugs represented by cisplatin play important roles in the treatment of various solid tumors. However, their applications are largely compromised by drug resistance and side effects. Much effort has been made to circumvent the drug resistance and general toxicity of these drugs. Among multifarious designs, monofunctional platinum(II) complexes with a general formula of [Pt(3A)Cl]⁺ (A: Ammonia or amine) stand out as a class of “non-traditional” anticancer agents hopeful to overcome the defects of current platinum drugs. This review aims to summarize the development of monofunctional platinum(II) complexes in recent years. They are classified into four categories: fluorescent complexes, photoactive complexes, targeted complexes, and miscellaneous complexes. The intention behind the designs is either to visualize the cellular distribution, or to reduce the side effects, or to improve the tumor selectivity, or inhibit the cancer cells through non-DNA targets. The information provided by this review may inspire researchers to conceive more innovative complexes with potent efficacy to shake off the drawbacks of platinum anticancer drugs.

Diclofenac-tethered Pt complexes restrain lactate formation from pyruvate and its transport by repressing LDHs and MCTs, polarize macrophages from M2 to M1 types, and impede angiogenesis, thus potentiating the anticancer activity and immune response.

A platinum(iv) complex DCP acts as a chemoimmunotherapeutic agent and induces cancer cell death by damaging DNA, stimulating immunogenic response, and enhancing phagocytosis.