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Taxol, a potent inhibitor of human HeLa and mouse fibroblast cell replication, blocked cells in the G2 and M phase of the cell cycle and stabilized cytoplasmic microtubules. The c oplasmic microtubules of taxol-treated cells were visualized by transmission electron microscopy and indirect immunofluorescence microscopy. More than 90% of the cells treated with 10 1AM taxol for 22 hr at 370C displayed bundles of microtubules that appeared to radiate from a common site (or sites), in addition to their cytoplasmic microtubules. Untreated cells that were kept in the cold (40C) for 16 hr lost their microtubules, whereas cells that were pretreated with taxol for 22 hr at 370C continued to display their microtubules and bundles of microtubules in the cold. Taxol inhibited the migration behavior of fibroblast cells, but these cells did not lose their ability to produce mobile surface projections such as lamellipodia and filopodia.Taxol was isolated from the plant Taxus brevifolia and characterized as an experimental antitumor drug by Wani et al. (1). Our work has shown that taxol enhances in vitro the rate, extent, and nucleation phase of microtubule polymerization and stabilizes microtubules. Microtubules assembled in vitro in the presence of taxol are resistant to depolymerization by cold (40C) or 4 mM CaC12. The optimal effects of the drug on in vitro polymerization and stabilization of microtubules are observed near stoichiometric equivalence with tubulin dimers (2).We now report that taxol is a potent inhibitor of the replication of HeLa and BALB/c fibroblast cells. HeLa cells treated with taxol accumulate in the G2 and M phase of the cell cycle. These cells contain microtubules plus bundles of microtubules all of which appear to have the structure of normal microtubules by transmission electron microscopy. Cytoplasmic microtubules in BALB/c fibroblasts treated with a concentration of taxol that completely inhibits the replication of these cells are resistant to depolymerization by cold (40C) or by 10,uM steganacin. This is consistent with our observation that microtubules treated with taxol in vitro become resistant to depolymerization.It has been reported that colchicine and other drugs that inhibit the polymerization of microtubules also inhibit fibroblast and macrophage cell migration but do not alter the ability of these cells to produce mobile surface projections (3-5). We find that taxol, a promoter and stabilizer of microtubules, completely inhibits fibroblast migration. However, the taxol-treated fibroblast cells are able to produce mobile lamellipodia and filopodia. Immunofluorescence. Cytoplasmic microtubules were visualized by indirect immunofluorescence microscopy (7). Fibroblast cells were grown on glass coverslips in tissue culture dishes (Falcon) and were allowed to attach for 24 hr prior to the addition of drug. After the cells were incubated with drug for the desired time, the coverslips were washed once in phosphate-buffered saline and fixed in 3.7% (wt/vol) formaldehyde for 8 min at room ...

A posteriori evidence suggests that radiotherapy to a targeted tumor can elicit an immune-mediated abscopal (ab-scopus, away from the target) effect in non-targeted tumors, when combined with an anti-cytotoxic T-lymphocyte antigen-4 monoclonal (CTLA-4) antibody. Concurrent radiotherapy and ipilimumab (a human monoclonal anti-CTLA-4 antibody) induced immune-mediated abscopal effects in poorly immunogenic pre-clinical tumor models and metastatic melanoma patients. However, no such reports exist for patients with metastatic lung adenocarcinoma. We report the first abscopal response in a treatment-refractory lung cancer patient treated with radiotherapy and ipilimumab. A post-treatment increase in tumor-infiltrating cytotoxic lymphocytes, tumor regression, and normalization of tumor markers was observed. One year after treatment with concurrent radiotherapy and ipilimumab the patient is without evidence of disease.

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ClinicalTrials.gov Identifier: NCT00551369.