Molecule

Description

Combination of Dexamethasone and Carboplatin shows a more markedly antitumor effects by 2–4-fold than either drug alone in LS174T (colon), MCF-7 and MDA-MB-468 (breast), A549 (lung) and glioma (U87-MG) xenograft models. ^[1] For A2780 cells, the concomitant treatment of hsp90 inhibitor 17-AAG and Carboplatin shows an antagonistic activity against cell proliferation with CI of 2.8. While combination treatment of 17-AAG and Carboplatin in different sequences leads to an additive inhibitory effect on cell proliferation with CI of 0.96 and 0.97 for the sequence 17-AAG followed by Carboplatin and Carboplatin followed by 17-AAG, respectively. ^[2] A recent study shows that mTOR inhibitor RAD001 in combination with Carboplatin results in synergistic inhibition of cell proliferation and caspase-independent apoptosis in breast cancer cell lines including MCF-7, tamoxifen-resistant MCF-7, and ZR-75 (all wild-type p53), SKBR-3 and BT-474 cell lines (all p53-mutated) with CI at EC50 of 0.228, 0.611, 0.599, 0.623 and 0.423, respectively. ^[3]Everolimus in combination with Paclitaxel and Carboplatin is currently in Phase II clinical trials in patients with Metastatic Melanoma.

Cell Lines

A2780, SKOV3, IGROV-1 and HX62

Concentrations

0-200 μM

Incubation Time

72 hours

Methods

3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assays: Exponentially growing A2780, SKOV3, IGROV-1 and HX62 ovarian cancer cells are plated in 96 well plates. A range of drug concentrations are added and the plates are incubated for 72 hours to allow for 3–4 doubling times. Each experiment is carried out in triplicate. Sulforhodamine B (SRB) assays: Exponentially growing A2780 cells are plated in 96 well microtitre plates. For experiments studying concomitant exposure, cells are exposed to increasing concentrations of both drugs for 96 hours. For experiments studying the effect of sequence of exposure to 17-AAG or carboplatin cells are exposed to increasing concentrations of 17-AAG or carboplatin for 24 hours. A period of 24-hour exposure to the first agent is chosen so that the A2780 cells would be exposed to the first drug for at least one doubling time (18-24 hours). The cells are then washed with sterile phosphate buffered saline and the medium is replenished. Following this, the second drug (to which the cells are not exposed to in the first 24 hours) or medium is added for 96 hours. All experiments are carried out in triplicate. The results of combination studies are analyzed using the well-established principles of median effect analysis method. The effects of the combination are calculated using an in-house spreadsheet.

Animal Models

The A2780 human ovarian cancer cell line is grown as a subcutaneous xenograft in female athymic NCr nude mice (nu/nu) in each flank.

Formulation

Carboplatin is dissolved in 43% ethanol, 33% polypropylene glycol and 24% cremaphor diluted 1:7 with sterile water.

Doses

≤60 mg/kg

Administration

Administered via i.p.