Antitumor effects of eribulin depend on modulation of the tumor microenvironment by vascular remodeling in mouse models.

We previously reported that eribulin mesylate (eribulin), a tubulin-binding drug (TBD), could remodel tumor vasculature (i.e. increase tumor vessels and perfusion) in human breast cancer xenograft models. However, the role of this vascular remodeling in antitumor effects is not fully understood. Here, we investigated the effects of eribulin-induced vascular remodeling on antitumor activities in multiple human cancer xenograft models. Microvessel densities (MVD) were evaluated by immunohistochemistry (CD31 staining), and antitumor effects were examined in 10 human cancer xenograft models. Eribulin significantly increased MVD compared to the controls in six out of 10 models with a correlation between enhanced MVD levels and antitumor effects (R2  = 0.54). Because of increased MVD, we next used radiolabeled liposomes to examine whether eribulin treatment would result in increased tumoral accumulation levels of these macromolecules and, indeed, we found that eribulin, unlike vinorelbine (another TBD) enhanced them. As eribulin increased accumulation of radiolabeled liposomes, we postulated that this treatment might enhance the antitumor effect of Doxil (a liposomal anticancer agent) and facilitate recruitment of immune cells into the tumor. As expected, eribulin enhanced antitumor activity of Doxil in a post-erlotinib treatment H1650 (PE-H1650) xenograft model. Furthermore, infiltrating CD11b-positive immune cells were significantly increased in multiple eribulin-treated xenografted tumors, and natural killer (NK) cell depletion reduced the antitumor effects of eribulin. These findings suggest a contribution of the immune cells for antitumor activities of eribulin. Taken together, our results suggest that vascular remodeling induced by eribulin acts as a microenvironment modulator and, consequently, this alteration enhanced the antitumor effects of eribulin.

[A case of rectal gastrointestinal stromal tumor in an elderly patient who was successfully treated with imatinib mesylate with no significant adverse events].

An 89-year-old male patient was found to have a mass with a diameter of 54 mm in the pelvic cavity, connected to the rectum, and was diagnosed with a gastrointestinal stromal tumor (GIST)of the rectum by transrectal biopsy. The patient was treated continuously with 400mg/day of imatinib mesylate with no significant adverse events, and the tumor gradually reduced in size. The tumor reduced in size to a diameter of 24 mm at 57 months post-treatment, and a partial response has been maintained for 60 months. Colorectal GIST is rare, comprising 5% of all GIST cases, and surgical resection is the first choice of treatment. In this case, due to a lack of consent, we chose imatinib mesylate as the treatment. However, imatinib mesylate has been reported to induce adverse events more frequently in older patients, and thus we took care to reduce the treatment dosage. We report this case to highlight that a normal quantity of imatinib mesylate can be administered, with no significant adverse events.

E6201, a novel kinase inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-1 and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase-1: in vivo effects on cutaneous inflammatory responses by topical administration.

E6201 [(3S,4R,5Z,8S,9S,11E)-14-(ethylamino)-8,9,16-trihydroxy-3,4-dimethyl-3,4,9,10-tetrahydro-1H-2-benzoxacyclotetradecine-1,7(8H)-dione)] is a novel anti-inflammatory agent that has potent inhibitory effects on the production of proinflammatory cytokines from leukocytes and antiproliferative activity on keratinocytes. To characterize the in vivo pharmacological activity of E6201, topically administered E6201 was evaluated in several different animal models of dermatitis. E6201 formulated as an ointment or cream showed dose-dependent inhibition of croton oil-induced acute edema formation and neutrophil infiltration into mouse skin. In addition, E6201 cream inhibited the 1-fluoro-2,4-dinitrobenzene-induced contact hypersensitivity reaction mediated by T cells in mice. In this model, E6201 cream also suppressed the migration of neutrophils and lymphocytes into the inflammatory site. Pretreatment with E6201 cream attenuated phorbol-12 myristate 13-acetate-induced ornithine decarboxylase activity, a marker of proliferation in epidermis. Furthermore, E6201 ointment showed inhibitory effects on both mezerein-induced and interleukin (IL)-23-induced epidermal hyperplasia. E6201 also suppressed T cell receptor-stimulated IL-17 production from human T cells. These results indicate that topically administered E6201 may be a useful agent for the prevention and treatment of cutaneous inflammatory and hyperproliferative diseases such as psoriasis.

Discovery of anti-inflammatory clinical candidate E6201, inspired from resorcylic lactone LL-Z1640-2, III.

Inspired by natural product, LL-Z1640-2, clinical candidate, E6201 (22) was discovered in a medicinal chemistry effort through total synthesis. The modification on C14-position to N-alkyl substitution showed to be potent in vitro and orally active in vivo in anti-inflammatory assays.

Discovery of an in vitro and in vivo potent resorcylic lactone analog of LL-Z1640-2 as anti-inflammatory lead, II.

The potent in vitro lead compound, ER-803064 (2), a MEK1 and MEKK1 inhibitor inspired from natural product LL-Z1640-2 (f152A1), was further optimized to improve in vitro and in vivo potency. The modifications on C14 position led to discovery of the lead compounds 28 and 29, which regained full in vitro potency of f152A1 and showed higher in vivo potency by iv administration.

E6201 [(3S,4R,5Z,8S,9S,11E)-14-(ethylamino)-8, 9,16-trihydroxy-3,4-dimethyl-3,4,9,19-tetrahydro-1H-2-benzoxacyclotetradecine-1,7(8H)-dione], a novel kinase inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)-1 and MEK kinase-1: in vitro characterization of its anti-inflammatory and antihyperproliferative activities.

The goal of this study is to identify a novel inhibitor with anti-inflammatory and antiproliferative properties for the treatment of psoriasis. Compound f152A1 [(3S,5Z,8S,11E)-8,9,16-trihydroxy-14-methoxy-3-methyl-3,4,9,10-tetrahydro-1H-benzo[c][1]oxacyclotetradecine1,7(8H)-dione] was identified as the main active metabolite with strong inhibitory activity against tumor necrosis factor-alpha (TNFalpha) transcription in a fraction originated from the fermentation broth of the fungus Curvularia verruculosa. Although active in cell-based assays, f152A1 was unstable in plasma and liver microsome preparations, thus limiting its pharmaceutical utilization. To improve the metabolic properties of f152A1, a medicinal chemistry program was undertaken, resulting in the generation of over 400 analogs of f152A1. Eventually, E6201 [(3S,4R,5Z,8S,9S,11E)-14-(ethylamino)-8,9,16-trihydroxy-3,4-dimethyl-3,4,9,19-tetrahydro-1H-2-benzoxacyclotetradecine-1,7(8H)-dione] was identified as a promising analog in this series. In the present study, we characterized the in vitro activities of E6201 and discovered that the compound inhibits lipopolysaccharide-activated TNFalpha reporter activity in THP-1-33 cells with an IC(50) value of 50 nM and selectively inhibits mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)-1 and MEK kinase-1 in cell-free biochemical assays. In addition, E6201 showed inhibitory activity in several other cell-based systems: 1) phosphorylation of c-jun N-terminal kinase and p38 MAPKs; 2) nuclear factor-kappaB and activated protein-1 activation in various cell types; 3) interleukin (IL)-2 production from human lymphocytes; 4) hyperproliferation of human keratinocytes; 5) IL-8 production from human keratinocytes; and 6) proinflammatory cytokine production from human peripheral blood mononuclear cells. Based on the data presented here, E6201 may be beneficial for treatment of inflammatory and hyperproliferative diseases such as psoriasis through its anti-inflammatory activities on immune cells and antihyperproliferative activities on keratinocytes.