panobinostat and Small-Cell-Lung-Carcinoma

In vitro data suggest that panobinostat (LBH589), a pan-deacetylase inhibitor, may add therapeutic benefit in the treatment of small-cell lung cancer (SCLC) with regression of tumors.. This multicenter, nonrandomized phase 2 trial was designed to evaluate antitumor activity of LBH589 in patients with previously treated SCLC. Patients received LBH589 administered intravenously at a dose of 20 mg/mq (days 1-8) every 21 days.. A total of 21 patients with extensive- or limited-stage SCLC were enrolled. Patients received a median of two cycles (range, 1-6). LBH589 was well tolerated, and the most common toxicities were grade 1 to 2 gastrointestinal disorders (nausea 38%, diarrhea 24%, vomiting 19%), grade 1 to 2 thrombocytopenia (14.3%). Of 19 patients evaluable for efficacy, two cases showed shrinkages more than 30% at first assessment, with time to progression of 14 and 21 weeks, respectively, and there were three long disease stabilizations of 12, 10, and 13 weeks. The study was prematurely closed because of a lack of activity.. This is the first report of a pan-deacetylase inhibitor inducing tumor shrinkage and sustained stable disease in SCLC. We believe that although the trial was prematurely discontinued, modest clinical activity of LBH589 combined with a favorable safety profile in pretreated SCLC patients was observed, which warrants further exploration of the potential contribution of LBH589 in other trials.

Topics: Aged; Antineoplastic Agents; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Lung Neoplasms; Male; Middle Aged; Panobinostat; Small Cell Lung Carcinoma

Because epigenetic inhibitors can reduce cancer cell proliferation, we tested the hypothesis that concurrent inhibition of histone acetylation and DNA methylation could synergistically reduce the viability of small cell lung cancer (SCLC) cells. Sub-IC(50) concentrations of the DNA methyltransferase (DNMT) inhibitor decitabine (5-AZA-dC) and the histone deacetylase (HDAC) inhibitors (LBH589 or MGCD0103) synergistically reduced the proliferation of five of nine SCLC cell lines. Loss of viability of sensitive SCLC cells did not correlate with the inhibition of either DNMT1 or HDACs, suggesting nonepigenetic mechanisms for synergy between these two classes of epigenetic modulators. Because combinations of 5-AZA-dC and HDAC inhibitors had marginal effects on the apoptosis index, Comet assay was undertaken to assess DNA damage. MGCD0103 and 5AZA-dC cotreatment augmented DNA damage in SCLC cells, resulting in increased tail length and moment in Comet assays by 24 hours in sensitive cell lines (P < 0.01). Consistent with augmented DNA damage, combination of a DNMT and HDAC inhibitor markedly increased the levels of phospho-H2A.X in sensitive cells but not in resistant ones. Comparison of basal gene expression between resistant and sensitive cells identified markedly higher basal expression of IFN-stimulated genes in the resistant cell lines, suggesting that IFN-stimulated gene expression may determine SCLC cell sensitivity to epigenetic modulators or other DNA damaging agents.

Topics: Apoptosis; Azacitidine; Benzamides; Cell Cycle; Cell Line, Tumor; Cell Survival; Decitabine; DNA (Cytosine-5-)-Methyltransferase 1; DNA (Cytosine-5-)-Methyltransferases; DNA Damage; DNA Methylation; Drug Resistance, Neoplasm; Drug Synergism; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Histones; Humans; Hydroxamic Acids; Indoles; Interferons; Lung Neoplasms; Panobinostat; Phosphorylation; Pyrimidines; Small Cell Lung Carcinoma