Small molecule Within the fields of molecular biology and pharmacology, a small molecule or micromolecule is a low molecular weight (≤ 1000 daltons) organic compound that may regulate a biological process, with a size on the order of 1 nm. Many drugs ...

drug conjugates or SMDCs are built with three modules: a targeting

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...

, a linker and a drug payload. The targeting ligands consist of low molecular weight, high-affinity ligands that are precisely linked to potent drugs. The linkers are designed to be stable in the bloodstream and then release the active drug from the targeting ligand when the SMDC is taken up by the diseased cell. The drug payloads are highly active molecules that are too toxic to be administered in their untargeted forms at therapeutic dose levels. This modular approach allows varying targeting ligands, linker systems and drug payloads and generate SMDCs for different diseases. The most advanced SMDC is

vintafolide Vintafolide is an investigational targeted cancer therapeutic currently under development by Endocyte and Merck & Co. It is a small molecule drug conjugate consisting of a small molecule targeting the folate receptor, which is overexpressed on ...

, a derivative of the anti-mitotic chemotherapy drug

vinblastine Vinblastine (VBL), sold under the brand name Velban among others, is a chemotherapy medication, typically used with other medications, to treat a number of types of cancer. This includes Hodgkin's lymphoma, non-small cell lung cancer, bladder ca ...

which is chemically linked to

folic acid Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...

. Potent, bioactive natural products like triptolide that inhibit mammalian transcription has been recently reported as a glucose conjugate for targeting hypoxic cancer cells with increased glucose transporter expression. SMDCs are currently being developed by

Endocyte Endocyte ( NASDAQ: ECYT) is a biopharmaceutical company established in 1996 and headquartered in West Lafayette, Indiana, a resident of the Purdue Research Park. In 2011 the company completed successfully an initial public offering (IPO). , the ...

for treating

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

, inflammatory diseases and kidney disease, as well as a companion imaging agent that is created by replacing the potent drug with an imaging agent.

References

{{Reflist Drug delivery devices