Fumiki Asanuma

Antitumor activity of paclitaxel against human breast carcinoma xenografts serially transplanted into nude mice

Paclitaxel (BMS‐181339: Taxol) is a promising agent against previously treated breast cancer. The antitumor activity of paclitaxel was evaluated using five human breast carcinoma xenografts in nude mice.

Acquired resistance to gemcitabine and cross-resistance in human pancreatic cancer clones.

The efficacy of gemcitabine (GEM), a standard treatment agent for pancreatic cancer, is insufficient because of primary or acquired resistance to this drug. Patients with tumors intrinsically sensitive to GEM gradually acquire resistance and require a shift to second agents, which are associated with the risk of cross-resistance. However, whether cross-resistance is actually present has long been disputed. Using six GEM-resistant and four highly GEM-resistant clones derived from the pancreatic cancer cell line BxPC-3, we determined the resistance of each clone and parent cell line to GEM and four anticancer agents (5-FU, CDDP, CPT-11, and DTX). The GEM-resistant clones had different resistances to GEM and other agents, and did not develop a specific pattern of cross-resistance. This result shows that tumor cells are heterogeneous. However, all highly GEM-resistant clones presented overexpression of ribonucleotide reductase subunit M1 (RRM1), a target enzyme for metabolized GEM, and showed cross-resistance with 5-FU. The expression level of RRM1 was high; therefore, resistance to GEM was high. We showed that a tumor cell acquired resistance to GEM, and cross-resistance developed in one clone. These results suggest that only cells with certain mechanisms for high-level resistance to GEM survive against selective pressure applied by highly concentrated GEM. RRM1 may be one of the few factors that can induce high resistance to GEM and a suitable therapeutic target for GEM-resistant pancreatic cancer.

Pharmacokinetics and postoperative analgesia of epidural tramadol: A prospective, pilot study

BACKGROUND Tramadol, a centrally acting analgesic drug, can be administered via multiple routes and is generally well tolerated. OBJECTIVE This study was designed to assess the pharmacokinetics of epidural tramadol administered preoperatively in Japanese patients undergoing upper abdominal surgery. METHOD Japanese patients who were scheduled to undergo upper abdominal surgery in The Kitasato Institute Hospital, Tokyo, Japan, were included. Patients received tramadol 2 mg/kg with 5 mL of 1% mepivacaine epidurally 10 minutes before incision. The serum concentration of tramadol was determined by high-performance liquid chromatography for 21 hours after administration. Serum concentration was determined before tramadol administration and 10, 20, 30, and 60 minutes after tramadol administration, first postoperative night, and first postoperative day. Pain score and adverse events (AEs) were assessed at 1, 3, 6, 12, 18, 24, 36, and 48 hours after surgery by patient interview. RESULTS Eleven patients were assessed for enrollment. Seven patients (6 men, 1 woman; mean [SD] age, 61.3 [12.6] years; mean [SD] weight, 59.9 [8.9] kg) provided consent and completed the study. The mean (SD) serum Cmax of tramadol was 1385.5 (390.8) ng/mL, Tmax was 0.33 (0.22) hour, and terminal elimination half-life (t1/2β) was 10.5 (2.3) hours. Four patients complained of nausea; however, only 1 patient was administered an antiemetic. No other AEs were reported. CONCLUSION This pilot study found that epidural tramadol administered before incision induced a Cmax within 30 minutes of administration. The drug was detected in serum at ∼21 hours after surgery.

The predictability of clinical antitumor effects using two distinctive in vitro chemosensitivity tests: An analysis of true positive cases

The results of two types of in vitro chemosensitivity tests, namely, the human tumor clonogenic assay (HTCA) and the succinic dehydrogenase inhibition assay (SDIA), for solid tumors, including stomach, colorectal and lung cancers, were analyzed and their correlation with clinical effects evaluated. The anticancer agents employed were mitomycin C (MMC), 5-fluorouracil (5-FU), adriamycin (ADM) and cisplatin (DDP). The evaluability rates of the assays were 54.5% for HTCA and 89.0% for SDIA. Among the 29 cases with evaluable lesions subjected to HTCA, there were 4 true positives, 9 false positives, and 16 true negatives, whereas among the 32 cases subjected to SDIA, the corresponding numbers were 2, 6, and 24, respectively. There were no false negatives for either assay, the accuracy of prediction for HTCA being 69.0% and for SDIA, 81.3%. The true positives of both assays included one complete response (CR) and five partial responses (PR), although the eventual outcome was cancer death in all cases. Interestingly, in five out of the six true positive cases, the agent involved was either ADM or DDP, both the which are usually regarded as “second line” anticancer agents for gastrointestinal carcinomas.

Combined cytotoxic and endocrine therapy for human breast carcinoma (Br-10) serially transplanted into nude mice

Cytotoxic and endocrine therapy on a human breast carcinoma (Br-10) serially transplanted into nude mice was given with reference to the sequence of drug administration. Mitomycin C (MMC) was combined with 2.5 mg/kg of tamoxifen (TAM). MMC was dissolved in 0.2 ml of physiological saline and administered intraperitoneally once weekly. TAM was dissolved in 0.1 ml of sesame oil and administered intramuscularly twice weekly. Both drugs were administered in the reverse sequence for 2 or 3 weeks. Cytosol estrogen receptor (ERc), nuclear estrogen receptor (ERn) and progesterone receptor (PgR), and3H-thymidine uptake labeling index (L.I.) were assayed after the treatment. When 1.5 mg/kg of MMC was combined with TAM, statistically significant differences were nil between the different sequential administrations. When the MMC administration was reduced to 0.75 mg/kg and 2 weeks, respectively, the MMC→TAM sequence was more effective than the reversed sequential administration. MMC preserved ERc and depressed L.I. to almost half of that of the control tumor. TAM generated the ER systems and slightly depressed L.I. These different modes of action between MMC and TAM on ER systems and L.I. may explain the antitumor effects of different sequential administrations.

Abstract P4-09-08: HOXB9, a gene promoting tumor angiogenesis and proliferation, is significantly associated with poor clincal outcomes in ER-positive breast cancer patients

Background: Studies have suggested that HOXB9 expression in breast cancer cells promotes cellular invasiveness, metastatic ability, and tumor neovascularization in the surrounding tissue in in vitro and in vivo assays. These findings imply that HOXB9 overexpression may alter tumor-specific cell fates and the tumor stromal microenvironment, contributing to breast cancer progression (Hayashida et al., PNAS 2010). We previously reported that clinical outcomes were significantly decreased in HOXB9-positive patients (Seki et al., Ann Surg Oncol. 2012). In this study, it was demonstrated that HER2 type and basal-like breast cancers were more associated with HOXB9 positivity than the luminal type. Therefore, it is required to identify more detail clinicopathological features most likely to be associated with HOXB9 overexpression. We investigated the correlation between HOXB9 overexpression and clinicopathological variables, and clinical outcomes in estrogen receptor (ER)-positive breast cancer patients. Patients and methods: A consecutive series of 118 ER-positive breast cancer patients who underwent surgical treatment were examined. HOXB9 expression was analyzed immunohistochemically using the anti-human HOXB9 polyclonal antibody. Immunostaining of Ki-67 and CD31 were also performed to evaluate tumor proliferation and angiogenesis. Results: The median age was 59 years and median observation period was 62 months. Of 118 tumor specimens immunostained for HOXB9, 49 specimens (41.5%) were positive staining. Univariate logistic regression revealed high nuclear grade (p Conclusions: Our results suggest that HOXB9 expression promoting the cellular proliferation and the angiogenesis in tumor microenvironment is a significant prognostic factor for clinical outcomes in ER-positive breast cancer patients. Further study might help to determine the application of anti-angiogenic therapy for metastatic ER-positive breast cancer patients. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-09-08.

Effect of a combination of S-1 and gemcitabine on cell cycle regulation in pancreatic cancer cell lines.

In a previous study, we showed that a combination of an oral fluoropyrimidine anticancer agent (S-1) and gemcitabine (GEM) had synergistic effects on cell growth and cell cycle arrest in the pancreatic cancer cell line MIA PaCa-2. Therefore, we conducted further mechanistic studies using the pancreatic cancer cell lines MIA PaCa-2 and SUIT-2. The combined effect of S-1 and GEM in SUIT-2 cells was evaluated using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the effects of S-1, GEM and S-1 plus GEM on cell cycle regulation were assessed using flow cytometry. We also examined the expression of several cell cycle regulatory proteins in both MIA PaCa-2 and SUIT-2 cells by western blotting. Classical isobolographic analysis of the MTT assay results showed that the combination of S-1 and GEM had a synergistic effect in SUIT-2 cells, and flow cytometric analysis of the cell cycle showed that the combination of S-1 plus GEM induced S-phase arrest to a greater degree than did either S-1 or GEM alone. Also, the combination of S-1 and GEM resulted in the downregulation of cyclin D1 expression and upregulation of cyclin A, p21 and p27 expression levels. Treatment of MIA PaCa-2 and SUIT-2 cells with a combination of both drugs also led to the increased phosphorylation of checkpoint kinase 1. Combined treatment with S-1 and GEM resulted in more prolonged S-phase arrest than with either treatment alone. This difference is shown to be potentially due to the higher levels of phosphorylated checkpoint kinase 1 in pancreatic cancer cell lines treated with the two agents.