Kunihiko Tatsumi

A novel brain-specific p53-target gene, BAI1, containing thrombospondin type 1 repeats inhibits experimental angiogenesis

The genetic alteration of p53 is associated with neovascularization during progression of glioma to its more malignant form, glioblastoma. Hence, one or more of the genes transactivated by p53 is likely to function as an angiogenesis inhibitors. We isolated a novel p53-inducible gene that encodes a 1584-amino-acid product containing five thrombospondin type 1 (TSP-type 1) repeats and is specifically expressed in the brain. A recombinant protein corresponding to the TSP-type 1 repeats of this gene product inhibited in vivo neovascularization induced by bFGF in the rat cornea. The expression of this gene, designated BAI1 (brain-specific angiogenesis inhibitor 1) was absent or significantly reduced in eight of nine glioblastoma cell lines, suggesting BAI1 plays a significant role in angiogenesis inhibition, as a mediator of p53.

A Novel Xanthine Dehydrogenase Inhibitor (BOF-4272)

An inhibitor of xanthine oxidase (XO)/xanthine dehydrogenase (XDH), an enzyme catalyzing the last step of purine catabolism, might be expected to be effective as remedy for hyperuricemia and possibly for ischemia-reperfusion injury. However, no clinically effective XO/XDH inhibitor except allopurinol have been used since it was introduced for clinical use in 1962 (1, 2).

Inhibition of Spontaneous Rat Osteosarcoma Lung Metastasis by 3S‐[4‐(Nhydroxyamino)‐2R‐isobutylsuccinyl]amino‐1‐methoxy‐3,4‐dihydrocarbostyril, a Novel Matrix Metalloproteinase Inhibitor

In the present experiment, we examined the effects of OPB‐3206, 3S‐[4‐(N‐hydroxyamino)‐2R isobutylsuccinyl] amino‐1‐methoxy‐3,4‐dihydrocarbostyril, a novel metalloproteinase inhibitor, on the growth and metastasis of transplantable osteosarcomas (spontaneous osteosarcoma, selected lung metastatic lesions; S‐SLM), which were previously established in rats. OPB‐3206 inhibited the activities of interstitial collagenase, gelatinases A and B, and stromelysin in vitro. After oral administration to rats, its serum concentration peaked at 40 min and the drug was no longer detectable at 8 h. When OPB‐3206 was orally administered at 0%, 0.1% and 0.4% in the diet for 4 weeks, starting 7 days after subcutaneous transplantation of osteosarcomas to male Fischer 344 rats, numbers of lung metastatic nodules were significantly reduced by the highest dose, while the growth of subcutaneous tumors was not affected. Zymographic analysis showed the presence of pro matrix metalloproteinase (proMMP)‐2, proMMP‐9 and MMP‐9 activities in S‐SLM. In animals fed 0.4% OPB‐3206, the activity of proMMP‐9 was increased, but that for MMP‐9 had become undetectable. The results thus suggest that OPB‐3206 selectively inhibits lung metastasis of rat transplantable osteosarcomas by inhibiting MMP‐9 activation.

A new synthetic matrix metalloproteinase inhibitor modulates both angiogenesis and urokinase type plasminogen activator activity

Proteolytic degradation of the extracellular matrix is essential to angiogenesis. Two families of proteases, the serine proteases of plasminogen activator/plasmin system and the matrix metalloproteinases (MMPs) are closely involved in these processes. The treatment of mice with a diet containing a new synthetic MMP inhibitor, OPB-3206: 3S-[4-(N-hydroxyamino)-2R-isobutylsuccinyl] amino-1methoxy-3, 4-dihydrocarbostyril, abrogated the development of new vessels in a rat corneal assay, and in a mouse Matrigel assay. In an in vitro angiogenesis model, OPB-3206 inhibited the migration and the tube formation of bovine aortic endothelial cells at 10–100 times lower concentrations than those required to inhibit the growth of these cells. OPB-3206 as well as other MMP inhibitory drugs, batimastat/BB-94 and marimastat/BB-2516, also selectively inhibited tubular morphogenesis in vitro. OPB-3206 reduced the activities of interstitial collagenase and type IV collagenase, but the concentrations of 50% inhibition against these MMPs were much higher than those of BB-94 and BB-2516. However, this new compound also inhibited urokinase type plasminogen activator activity on fibrin zymogram, while BB-94 and BB-2516 did not. Furthermore, the addition of urokinase type plasminogen activator reduced the inhibitory effect of the tubular morphogenesis of vascular endothelial cells by OPB-3206. The treatment of mice with a diet containing this new compound also reduced the growth of implanted mammary carcinomas as well as the lung metastasis of colon carcinoma. The anti-angiogenic effect of OPB-3206 appeared to be associated with its inhibition of tumor growth and metastasis.

Abstract B118: A phase 1, open-label multiple dose escalation trial to determine safety and tolerability of once daily OPB-111077 in subjects with advanced cancer

Background: OPB-111077 is a new chemical entity with anticancer activity in vitro and in human tumor xenograft models. The compound modulates STAT3 phosphorylation but has no marked effect on activity of any of 69 tested human tyrosine or serine/threonine kinases. This P1 study evaluated safety, pharmacokinetics, and antitumor activity of OPB-111077 in subjects with advanced cancers. Methods: Primary objectives determined safety, tolerability, and maximum tolerated dose (MTD) of OPB-111077 given orally once daily to subjects with advanced cancer. Secondary objectives included pharmacokinetics (PK) and antitumor activity. In the first 2 cycles of dose escalation, Day 1 dose was followed by 2 days off study therapy for PK. The starting dose was 100 mg once daily. Single subject cohorts with dose level doublings were studied until the first ≥ Grade 2 AE that was possibly drug-related. Then a 3+3 design was used. After MTD determination, expansion cohorts were opened for subjects with malignancies possibly susceptible to inhibition by OPB-111077, including breast, cervical, colorectal, gastric, kidney, myeloma, non-small cell lung, non-Hodgkin9s lymphoma, ovarian, and prostate cancers, as well as “rare tumors” for which STAT3 inhibition might generate clinical activity. Results: Overall 145 subjects received OPB-111077. Mean age was 61 years (range 21-88), and 51% of subjects were female. Dose escalation occurred in 18 subjects. Four DLTs were observed: 2 at 400 mg QD (G3 nausea/vomiting), and 2 at 300 mg QD (G3 vertigo and G3 nausea/vomiting). The MTD was 250 mg QD. All subjects recovered from DLTs after drug discontinuation. Adverse events (AEs) that may be attributable to OPB-111077 include nausea (71%), vomiting (46%), fatigue (44%), dizziness/vertigo (26%), and hypothyroidism (19%). Most AEs were CTCAE Grades 1 or 2 and manageable with supportive treatment. OPB-111077 exposures increase dose proportionally and linearly with increasing single and multiple doses up to 250 mg. Median time to peak plasma concentration (tmax) is about 4 hours. Mean maximum plasma concentration (Cmax) is 16 μmol/L and mean trough concentration is 6 μmol/L after multiple doses of 250 mg QD. Terminal half-life is about 23 hours and steady state was reached by about 1 week. The major metabolites in plasma are pharmacologically inactive and unlikely to contribute to efficacy. Administration with a high fat meal did not significantly alter OPB-111077 bioavailability. Expansion cohorts enrolled 127 subjects, including NSCLC (13), breast (13), ovarian (11), kidney (11), colorectal (10), prostate (8), lymphoma (8), gastric (7), cervical (3) cancers, and myeloma (1). Rare tumors with STAT rationale included sarcomas (13), neuroendocrine tumors (7), squamous cell carcinomas (5), other carcinomas (12), and other malignant tumors (5). One RECIST Partial Response occurred in a subject with Diffuse Large B Cell Lymphoma. In addition, 7 subjects with had stable disease for at least 8 treatment cycles, including gastric (2), cholangiocarcinoma, kidney, prostate, K-Ras mutant colon cancer, and esthesioneuroblastoma. Conclusions: OPB-111077 can be given safely and achieves clinically active drug levels in humans. Single agent clinical activity was observed. Translational work is ongoing to determine factors driving clinical activity Citation Format: Gregory Cote, Kyriakos Papadopoulos, Amita Patnaik, Drew Rascoe, Lon Smith, Andrea Bullock, Keith Flaherty, Geoffrey Shapiro, Jordan Berlin, Manish Monga, Thomas Habermann, Thomas Witzig, Chester Lin, Lin-Feng Tsai, Agnes Elekes, Naoto Ohi, Kunihiko Tatsumi, Anthony Tolcher. A phase 1, open-label multiple dose escalation trial to determine safety and tolerability of once daily OPB-111077 in subjects with advanced cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B118.