Anti-MMAE monoclonal antibody, HRP

Methyl auristatin E, abbreviated as MMAE, molecular formula: C39H67N5O7, CAS number: 474645-27-7, peptide sequence: Me-Val-Val-Unk, is a synthetic anti-tumor drug. Due to its toxicity, it cannot be used as a drug on its own but is linked to a monoclonal antibody (MAB). MMAE is a potent antimitotic drug derived from a polypeptide called dolastatin present in the marine shellless mollusk dolabellaauricularia. These drugs are up to 200 times more potent than vinblastine. Studies have shown that MMAE can disrupt the microtubule dynamics of cells, block the polymerization of intracellular tubulin, cause cell cycle arrest, inhibit cell division, induce cell apoptosis, and then inhibit cell growth and proliferation, thereby achieving for anti-tumor purposes, it has good activity against various malignant tumors such as gastric cancer, lymphoma and breast cancer. However, MMAE is highly toxic and a poorly soluble small molecule. After intravenous injection, it is often distributed throughout the body, causing serious toxicity and adverse reactions to normal tissues. Therefore, MMAE cannot be administered by intravenous drip. At present, it is only used in antibody-drug conjugates. So far, about half of ADC drugs use MMAE. According to international naming guidelines, all ADC drugs that use MMAE must add vedotin after the name, so as long as you see the name Next is vedotin, which means it uses MMAE. The most famous one at present is Brentuximab vedotin (CD30 antibody conjugate drug, BV).

Figure 1. Permeability and retention (EPR) effect of FRRG-MMAE nanoparticles in a breast tumor model. (Source: Cho H, et al. 2022)

ADC (Antibody–drug conjugates) is an antibody drug conjugate, which consists of three parts: a monoclonal antibody, a coupling chain (linker), and a cytotoxic molecule drug. The monoclonal antibody serves as a carrier to target the cytotoxic molecule (i.e., payload). Transported to target cells to play a role, ADC drugs fill the gap between antibody drugs and traditional chemotherapy drugs, improve the specificity of the drug and improve the treatment window, directional release, and more controllable safety. It is the hot research current field of tumor treatment. There are two main types of payloads in ADC: the first type is tubulin inhibitors that disrupt microtubule assembly and affect mitosis, such as Auristatin, DM1, MMAE, and MMAF (Monomethyl auristatin F). The second category is DNA damaging drugs, such as PDB and ducarmycin. Microtubules are the main component of the cytoskeleton and play an important role in the process of cell division. Since tumor cells will maintain rapid proliferation, tubulin inhibitors that interfere with tumor cell mitosis have become one of the directions for tumor drug development. This type of inhibitor mainly inhibits the polymerization of tubulin or promotes the polymerization of tubulin. Among them, MMAE is a typical agent that promotes tubulin polymerization. It acts on the β-subunit of α-β tubulin dimer, causing the growth of microtubules to be unregulated. It is a popular and effective agent in ADC drug load development.

MMAE is 100-1000 times more potent than doxorubicin and cannot be used as a drug itself. However, as part of the ADC, MMAE is linked to a monoclonal antibody (mAb) that recognizes specific marker expression in cancer cells and directs MMAE to specific target cancer cells. The linker connecting MMAE to the monoclonal antibody is stable in the extracellular fluid, but once the ADC binds to the target cancer cell antigen and enters the cancer cell, it is cleaved by cathepsin, after which the ADC releases toxic MMAE and activates effective anti-mitotic activity mechanism. ADCs can enhance the antitumor effects of antibodies and reduce the adverse systemic effects of potent cytotoxic drugs. Cytotoxic molecules are the key to determining the lethality of ADC. In addition to being extremely toxic, they also need to have sufficient water solubility and stability in serum. Among them, MMAE is the most widely used drug on the market. They are polypeptides composed of 5 units. The molecules are highly stable. They are found in plasma, liver lysosomal extracts or proteases such as tissues. No signs of degradation in proteinase B. MMAE has also shown strong activity in some clinical trials of lymphoma, leukemia and solid tumors. Among the approved ADC drugs, ADC drugs with a payload of MMAE account for nearly 50%.

Monomethyl auristatin E