Cancer is a term used to describe a wide variety of diseases that are each characterized by the uncontrolled, malignant growth of a particular type of cell. It begins in a tissue containing such a cell and, if the cancer has not spread to any additional tissues at the time of diagnosis, may be treated by, for example, surgery, radiation, or another type of localized therapy. However, when there is evidence that cancer has metastasized from its tissue of origin, different approaches to treatment are typically used. Indeed, because it is not possible to determine the extent of metastasis, systemic approaches to therapy are usually undertaken when any evidence of spread is detected. These approaches involve the administration of, for example, chemotherapeutic drugs that interfere with the growth of rapidly dividing cells, such as cancer cells.
Halichondrin B is a structurally complex, macrocyclic compound that was originally isolated from the marine sponge Halichondria okadai, and subsequently was found in Axinella sp., Phakellia carteri, and Lissodendoryx sp. A total synthesis of halichondrin B was published in 1992 (Aicher et al., J. Am. Chem. Soc. 114:3162-3164, 1992). Halichondrin B has been shown to inhibit tubulin polymerization, microtubule assembly, betas-tubulin crosslinking, GTP and vinblastine binding to tubulin, and tubulin-dependent GTP hydrolysis in vitro. This molecule has also been shown to have anti-cancer properties in vitro and in vivo. Halichondrin B analogs having anti-cancer activities are described in U.S. Pat. No. 6,214,865 B1.
Eribulin is a synthetic analog of halichondrin B. Eribulin is also known as ER-086526, and has been assigned CAS number 253128-41-5 and US NCI designation number NSC-707389. The mesylate salt of eribulin (eribulin mesylate, which is marketed under the trade name HALAVEN® and is also known as E7389) is approved for the treatment of patients with breast cancer who have previously received at least two chemotherapeutic regimens for the treatment of metastatic disease that should have included an anthracycline and a taxane in either the adjuvant or metastatic setting.
The chemical name for eribulin mesylate is (2R,3R,3aS,7R,8aS,9S,I0aR,11S,12R,13aR,13bS,15S,18S,21S,24S,26R,28R,29aS)-2-[(2S)-3-amino-2-hydroxypropyl]hexacosahydro-3-methoxy-26-methyl-20,27-bis(methylene)-11,15:18,21:24,28-triepoxy-7,9-ethano-12,15-methano-9H,15H-furo[3,2-i]furo[2′,3′:5,6]pyrano[4,3-b][1,4]dioxacyclopentacosin-5(4H)-one, methanesulfonate (salt), and it can be depicted as:

E7080 (also known as lenvatinib mesylate) is an active inhibitor of multiple receptor tyrosine kinases (e.g., receptor tyrosine kinases involved in angiogenesis and tumor proliferation) including vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), platelet-derived growth factor receptor α (PDGFRα), KIT, and RET proto-oncogene receptors. It has been assigned CAS number 857890-39-2 (also see 417716-92-8). The chemical name for lenvatinib mesylate is 4-[3-chloro-4-[[(cyclopropylamino)carbonyl]amino]phenoxy]-7-methoxy-6-quinolinecarboxamide, methanesulfonate (1:1). [It is also named as 4-[3-chloro-4-(N′-cyclopropylureido)phenoxyl]-7-methoxyquinoline-6-carboxamide, and N-{4-[(6-carbamoyl-7-methoxyquinolin-4-yl)oxy]-2-chlorophenyl}-N′-cyclopropylurea monomethanesulfonate.] Lenvatinib mesylate can be depicted as:

USPTO Backgrounds
USPTO Backgrounds