The BH3 mimetic ABT-737 increases treatment efficiency of paclitaxel against hepatoblastoma

Abstract

BackgroundThe primary goal of current chemotherapy in hepatoblastoma (HB) is reduction of tumour volume and vitality to enable complete surgical resection and reduce risk of recurrence or metastatic disease. Drug resistance remains a major challenge for HB treatment. In some malignancies inhibition of anti-apoptotic pathways using small BH3 mimetic molecules like ABT-737 shows synergistic effects in combination with cystotoxic agents in vitro. Now we analysed toxicology and synergistic effects of this approach in HB cells and HB xenografts.MethodsViability was monitored in HB cells (HUH6 and HepT1) and fibroblasts treated with paclitaxel, ABT-737 and a combination of both in a MTT assay. HUH6 xenotransplants in NOD/LtSz-scid IL2Rγnull mice (NSG) were treated accordingly. Tumour volume and body weight were monitored. Xenografted tumours were analysed by histology and immunohistochemistry (Ki-67 and TUNEL assay).ResultsABT-737 reduced viability in HUH6 and HepT1 cells cultures at concentrations above 1 μM and also enhanced the cytotoxic effect of paclitaxel when used in combination. Thereby paclitaxel could be reduced tenfold to achieve similar reduction of viability of tumour cells. In contrast no toxicity in fibroblasts was observed at the same regiments. Subcutaneous HB (HUH6) treated with paclitaxel (12 mg/kg body weight, n = 7) led to delayed tumour growth in the beginning of the experiment. However, tumour volume was similar to controls (n = 5) at day 25. Combination treatment with paclitaxel and ABT-737 (100 mg/kg, n = 8) revealed significantly 10 fold lower relative tumour volumes compared to control and paclitaxel groups. Paclitaxel dependent toxicity was observed in this mice strain.ConclusionsOur results demonstrate enhancement of chemotherapy by using modulators of apoptosis. Further analyses should include improved pharmacological formulations of paclitaxel and BH3 mimetics in order to reduce toxicological effects. Sensitising HB to apoptosis may also render resistant HB susceptible to established chemotherapy regimens.

Targeting EpCAM (CD326) for immunotherapy in hepatoblastoma

“…Spare tumor tissue was sliced in culture media with two scalpels as longitudinal sections of 2–3 mm thickness. Tissue slices were adapted to culture for 8 h. The sections were then placed in fresh culture media and incubated for 1 h until GLuc activity was assessed 42 . One million γδ T cells cells were added to the slice cultures and incubated for 20 h. Where indicated, 5 µg/mL MT110 were added.…”

Intramuscular Transplantation Improves Engraftment Rates for Esophageal Patient-Derived Tumor Xenografts

“…Athymic nude mice were selected for this purpose because of the ease of tumor detection and better tolerance of the chemotherapy. 17,18 Once tumors reached a volume of 125 mm 3 , the mice were randomized to receive either matched patient chemotherapy [5-fluorouracil (5FU)/cisplatin] or the vehicle (0.9 % NaCl) alone. Cisplatin (DBL) was suspended in 0.9 % (w/ v) NaCl and administered at a dose of 4 mg/kg via intraperitoneal injection on a weekly basis for 3 weeks.…”

Increased efficacy of CDDP in a xenograft model of hepatoblastoma using the apoptosis sensitizer ABT-737

“…an increase in apoptosis. ABT-737 as a single agent has shown activity against several hematopoietic cell lines (leukemia, multiple myeloma and cultured lymphoma) and various solid tumors, including HB in vitro (11,(13)(14)(15)(16)(17)(18). Highly synergistic in vivo effects have been described when combining ABT-737 with established chemotherapeutic drugs commonly used in treatment protocols of HB, including CDDP (11,19,20).…”

“…Drugs. ABT-737 (Abbott GmbH & Co. KG, Wiesbaden, Germany) was dissolved for in vitro and animal studies as previously described (14). The final concentration in the cell culture was 0.01, 0.1, 0.3 and 1 µM.…”

“…Histology and immunohistochemistry. Paraffin-embedded sections obtained from xenografted tumors were used for immuno histochemical staining against Ki-67 (mouse antihuman Ki-67, 1:400; Dako GmbH, Hamburg, Germany) as previously described (14). The proliferation index was expressed as the mean ± SD of positively stained cells per microscopic field of two regions in each tumor of the treatment groups.…”