An activating mutation of () is the most frequent genetic alteration associated with poor prognosis in acute myeloid leukemia (AML). Although many FLT3 inhibitors have been clinically developed, no first-generation inhibitors have demonstrated clinical efficacy by monotherapy, due to poor pharmacokinetics or unfavorable safety profiles possibly associated with low selectivity against FLT3 kinase. Recently, a selective FLT3 inhibitor, quizartinib, demonstrated favorable outcomes in clinical studies. However, several resistant mutations emerged during the disease progression. To overcome these problems, we developed a novel FLT3 inhibitor, FF-10101, designed to possess selective and irreversible FLT3 inhibition. The co-crystal structure of FLT3 protein bound to FF-10101 revealed the formation of a covalent bond between FF-10101 and the cysteine residue at 695 of FLT3. The unique binding brought high selectivity and inhibitory activity against FLT3 kinase. FF-10101 showed potent growth inhibitory effects on human AML cell lines harboring internal tandem duplication (-ITD), MOLM-13, MOLM-14, and MV4-11, and all tested types of mutant FLT3-expressing 32D cells including quizartinib-resistant mutations at D835, Y842, and F691 residues in the FLT3 kinase domain. In mouse subcutaneous implantation models, orally administered FF-10101 showed significant growth inhibitory effect on FLT3-ITD-D835Y- and FLT3-ITD-F691L-expressing 32D cells. Furthermore, FF-10101 potently inhibited growth of primary AML cells harboring either -ITD or-D835 mutation in vitro and in vivo. These results indicate that FF-10101 is a promising agent for the treatment of patients with AML with mutations, including the activation loop mutations clinically identified as quizartinib-resistant mutations.

Lung neoplasm, in place of gastric cancer, is the major cause of cancer mortality in Japan as well as in the USA (Travis et al, 1995). Despite the advances in diagnostic techniques for the early detection of lung cancer and the significant improvement in surgical procedures, the survival rate of lung cancer patients is poor even in the early stages of cancer as compared to the other malignant neoplasms. From a clinical point of view, one of the most troublesome impediments for treatment of lung cancer is the metastasis to mediastinal lymph nodes (n = 2 and n = 3 lung cancer) from the primary lesion (Jefferson et al, 1996). If metastases were inhibited by the present and/or new therapies, the prognosis of patients with lung cancer would improve. According to new TNM revisions (Mountain, 1997), it is difficult to say if the 5-year survival rate of n ³ 2 in lung cancer patients is an improvement, although a standard operative technique has been established to resect mediastinal lymph nodes (Vansteenkiste et al, 1997), except for aortic lymph node metastasis (Nakanishi et al, 1997). Therefore, biological approaches and studies, such as interference with lymph node metastasis or management of downstaging to the patients with lymph node metastasis, combined with surgery are required for lung cancer therapy. To do this, suitable animal models that conform to the clinical features are also necessary to search for novel therapies of lung cancer and to evaluate the efficacy of new drugs. However, there are few models for the formation of a solitary pulmonary nodule by orthotopic implantation of lung cancer cells and subsequent lymph node metastasis. In the present study, we attempted to establish a simple model for a solitary lung tumour and its lymph node metastasis by intrapulmonary implantation of Lewis lung carcinoma (LLC) cells in mice. MATERIAL AND METHODS AnimalsSpecific pathogen-free female C57BL/6 mice at 6 weeks old, were purchased from Japan SLC, Inc, Hamamatsu, Japan. They were maintained in the Laboratory for Animal Experiments, Research Institute for Wakan-Yaku Toyama Medical and Pharmaceutical University, under laminar air-flow conditions. All animals had free access to standard laboratory mouse food and water ad libitum. Housing was temperature controlled with a 12-h light and dark cycle. This study was conducted in accordance with the standards established by the Guidelines for the Care and Use of Laboratory Animals of Toyama Medical and Pharmaceutical University. Summary This study is designed to establish a pulmonary tumour model to investigate the biology and therapy of lung cancer in mice. Current methods for forming a solitary intrapulmonary nodule and subsequent metastasis to mediastinal lymph nodes are not well defined. Lewis lung carcinoma (LLC) cell suspensions were orthotopically introduced into the lung parenchyma of C57/BL6 mice via a limited skin incision without thoracotomy followed by direct puncture through the intercostal space. The implantation process was performed within approximately ...

We have investigated the inhibitory effect of oral administration of Juzen-taiho-to, a Kampo Japanese herbal medicine, on liver metastasis by the inoculation of a liver-metastatic variant (L5) of murine colon 26 carcinoma cells into the portal vein. Oral administration of Juzen-taiho-to for 7 days before tumor inoculation resulted in dose-dependent inhibition of liver tumor colonies and significant enhancement of survival rate as compared with the untreated control, without side effects. We also found that liver metastasis of L5 cells was enhanced in BALB/c mice pretreated with anti-asialo GM1 serum or 2-chloroadenosine, and in BALB/c nu/nu mice, compared to normal mice. This indicates that NK cells, macrophages, and T-cells play important roles in the prevention of metastasis of tumor cells. Juzen-taiho-to significantly inhibited the experimental liver metastasis of colon 26-L5 cells in mice pretreated with anti-asialo GM 1 serum and untreated normal mice, whereas it did not inhibit metastasis in 2-chloroadenosine-pretreated mice or T-cell-deficient nude mice. Oral administration of Juzen-taiho-to activated peritoneal exudate macrophages (PEM) to become cytostatic against the tumor cells. These results show that oral administration of Juzentaiho-to inhibited liver metastasis of colon 26-L5 cells, possibly through a mechanism mediated by the activation of macrophages and/or T-cells in the host immune system. Thus, Juzen-taiho-to may be efficacious for the prevention of cancer metastasis. Key words: Juzen-taiho-to -Liver metastasis -Colon 26-L5 -MacrophageDespite the advances in diagnostic techniques for the early detection of colon cancer and the significant improvement in surgical procedures, the mortality rate of colon cancer has been increasing year after year, [1][2][3] and metastasis is a frequent cause of death by cancer. The liver is the most common target of hematogenous metastasis in gastrointestinal tract cancer, especially colon cancer, and the prognosis for cases with liver metastasis is extremely poor. 4,5) If occult micrometastases, established at the time of surgery, could be inhibited, then the prognosis of patients with colon carcinoma would improve. Suitable experimental metastasis models of colon carcinoma are necessary to develop novel therapies for colon carcinoma. Murine colon 26 carcinoma cells have been utilized in an experimental model of metastasis in BALB/ c mice.6) We have established a liver-metastatic variant (colon 26-L5) of the colon 26 carcinoma by an in vivo selection method.7) Colon 26-L5 cells predominantly metastasize in the liver after inoculation via the portal vein of BALB/c mice. This model has provided a means for evaluating the efficacy of treatments for liver metastasis of cancer, especially for occult micrometastases.

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