Citations

Abstract Purpose: To evaluate the effects of combining the multiple receptor tyrosine kinase inhibitor AEE788 and histone deacetylase (HDAC) inhibitors on cytotoxicity in a broad spectrum of cancer cell lines, including cisplatin-resistant ovarian adenocarcinoma cells. Experimental Design: Multiple cancer cell lines were treated in vitro using AEE788 and HDAC inhibitors (LBH589, LAQ824, and trichostatin A), either alone or in combination. Effects on cytotoxicity were determined by growth and morphologic assays. Effects of the combination on cell signaling pathways were determined by Western blotting, and the results were confirmed using pathway-specific inhibitors and transfection of constitutively active proteins. Results: Cell treatment with AEE788 and HDAC inhibitors (LBH589, LAQ824, and trichostatin A) in combination resulted in synergistic induction of apoptosis in non–small cell lung cancer (MV522, A549), ovarian cancer (SKOV-3), and leukemia (K562, Jurkat, and ML-1) cells and in OV202hp cisplatin-resistant human ovarian cancer cells. AEE788 alone or in combination with LBH589 inactivated mitogen-activated protein kinase (MAPK) and Akt cascades. Inhibition of either MAPK and/or Akt enhanced LBH589-induced apoptosis. In contrast, constitutively active MAPK or Akt attenuated LBH589 or LBH589 + AEE788–induced apoptosis. Increased apoptosis was correlated with enhanced reactive oxygen species (ROS) generation. The free radical scavenger N-acetyl-l-cysteine not only substantially suppressed the ROS accumulation but also blocked the induction of apoptosis mediated by cotreatment with AEE788 and LBH589. Conclusion: Collectively, these results show that MAPK and Akt inactivation along with ROS generation contribute to the synergistic cytotoxicity of the combination of AEE788 and HDAC inhibitors in a variety of human cancer cell types. This combination regimen warrants further preclinical and possible clinical study for a broad spectrum of cancers.

AbstractOutcomes for older adults with acute myelogenous leukemia (AML) are poor due to both disease and host-related factors. In this phase 2 study, we tested the oral farnesyltransferase inhibitor tipifarnib in 158 older adults with previously untreated, poor-risk AML. The median age was 74 years, and a majority of patients had antecedent myelodysplastic syndrome. Complete remission (CR) was achieved in 22 patients (14%); partial remission or hematologic improvement occurred in 15 patients, for an overall response rate of 23%. The median duration of CR was 7.3 months and the median survival of complete responders was 18 months. Adverse karyotype, age 75 years or older, and poor performance status correlated negatively with survival. Early death in the absence of progressive disease was rare, and drug-related nonhematologic serious adverse events were observed in 74 patients (47%). Inhibition of farnesylation of the surrogate protein HDJ-2 occurred in the large majority of marrow samples tested. Baseline levels of phosphorylated mitogen-activated protein kinase and AKT did not correlate with clinical response. Tipifarnib is active and well tolerated in older adults with poor-risk AML and may impart a survival advantage in those patients who experience a clinical response.

Abstract Purpose: To determine the maximum tolerated dose (MTD), dose-limiting toxicity, and pharmacokinetics of 17-allylamino-demethoxy-geldanamycin (17-AAG) administered on days 1, 4, 8, and 11 every 21 days and to examine the effect of 17-AAG on the levels of chaperone and client proteins. Experimental Design: A phase I dose escalating trial in patients with advanced solid tumors was done. Toxicity and tumor responses were evaluated by standard criteria. Pharmacokinetics were done and level of target proteins was measured at various points during cycle one. Results: Thirteen patients were enrolled in the study. MTD was defined as 220 mg/m2. Dose-limiting toxicities were as follows: dehydration, diarrhea, hyperglycemia, and liver toxicity. At the MTD, the mean clearance of 17-AAG was 18.7 L/h/m2. There was a significant decrease in integrin-linked kinase at 6 hours after infusion on day 1 but not at 25 hours in peripheral blood mononuclear cells. Treatment with 17-AAG on day 1 significantly increased pretreatment levels of heat shock protein (HSP) 70 on day 4, which is consistent with the induction of a stress response. In vitro induction of a stress response and up-regulation of HSP70 resulted in an increased resistance to HSP90-targeted therapy in A549 cells. Conclusions: The MTD of 17-AAG on a twice-weekly schedule was 220 mg/m2. Treatment at this dose level resulted in significant changes of target proteins and also resulted in a prolonged increase in HSP70. This raises the possibility that HSP70 induction as part of the stress response may contribute to resistance to 17-AAG.

Abstract This study was undertaken to characterize preclinical cytotoxic interactions for human malignancies between the multikinase inhibitor sorafenib (BAY 43-9006) and proteasome inhibitors bortezomib or MG132. Multiple tumor cell lines of varying histiotypes, including A549 (lung adenocarcinoma), 786-O (renal cell carcinoma), HeLa (cervical carcinoma), MDA-MB-231 (breast), K562 (chronic myelogenous leukemia), Jurkat (acute T-cell leukemia), MEC-2 (B-chronic lymphocytic leukemia), and U251 and D37 (glioma), as well as cells derived from primary human glioma tumors that are likely a more clinically relevant model were treated with sorafenib or bortezomib alone or in combination. Sorafenib and bortezomib synergistically induced a marked increase in mitochondrial injury and apoptosis, reflected by cytochrome c release, caspase-3 cleavage, and poly(ADP-ribose) polymerase degradation in a broad range of solid tumor and leukemia cell lines. These findings were accompanied by several biochemical changes, including decreased phosphorylation of vascular endothelial growth factor receptor-2, platelet-derived growth factor receptor-β, and Akt and increased phosphorylation of stress-related c-Jun NH2-terminal kinase (JNK). Inhibition of Akt was required for synergism, as a constitutively active Akt protected cells against apoptosis induced by the combination. Alternatively, the JNK inhibitor SP600125 could also protect cells from apoptosis induced by the combination, indicating that both inhibition of Akt and activation of JNK were required for the synergism. These findings show that sorafenib interacts synergistically with bortezomib to induce apoptosis in a broad spectrum of neoplastic cell lines and show an important role for the Akt and JNK pathways in mediating synergism. Further clinical development of this combination seems warranted. [Mol Cancer Ther 2006;5(9):2378–87]

Abstract In spite of recent advances in molecular biology leading to the introduction of clinically active novel agents, such as imatinib, erlotinib, and bevacizumab, therapy of the most common epithelial tumors, such as lung cancer, remains unsuccessful. The diversity of molecular abnormalities in these tumors is felt to partly contribute to their resistance to therapy. It is, therefore, widely accepted that one approach to improving the efficacy of cancer therapy is the development of rational, hypothesis-based combinations of anticancer agents that may exhibit synergistic cytotoxic interactions. A number of empirical combination studies with the epidermal growth factor receptor and classic cytotoxic agents were undertaken in clinical trials, with disappointing results. It is, therefore, felt that preclinical combinations of epidermal growth factor receptor inhibitors and other novel agents, based on sound knowledge of complementary signaling pathways whose concerted inhibition would be hypothesized to inhibit growth, is the reasonable approach in the future. A brief overview of some of these pathways (mammalian target of rapamycin, vascular endothelial growth factor receptor, and ras/mitogen-activated protein kinase signaling) is provided in this review.

Purpose The maximum tolerated dose (MTD) and the dose-limiting toxicities of EKB-569, a selective, irreversible inhibitor of the epidermal growth factor receptor (EGFR), when administered orally once daily on an intermittent-dose schedule (14 days of a 28-day cycle) or on a continuous-dose schedule (each day of a 28-day cycle), were determined in patients with advanced solid tumors. Patients and Methods Planned dose escalation was 25, 50, 75, 125, 175, and 225 mg. Pharmacokinetic sampling was performed on days 1 and 14 for the intermittent-dose cohort and on days 1 and 15 for the continuous-dose cohort. Results Thirty patients received a median of two cycles (range, one to 10 cycles) in the intermittent-dose cohort; 29 patients received a median of three cycles (range, one to eight cycles) in the continuous-dose cohort. Dose-limiting toxicity was grade 3 diarrhea, and the MTD was 75 mg EKB-569 per day for both cohorts. Other common toxicities included rash, nausea, and asthenia. Exposure to EKB-569 was dose proportional. At the MTD, the mean ± standard deviation terminal half-life was 21.7 ± 4.2 hours and peak concentration increased 1.2-fold from day 1 to day 14/15. No major antitumor responses were observed. However, one patient with non–small-cell lung cancer and one with cutaneous squamous cell carcinoma had stable disease for 33 and 24 weeks, respectively. Conclusion The MTD of once-daily oral EKB-569 is 75 mg. The tolerable toxicity profile and long half-life of this irreversible EGFR inhibitor warrant its further evaluation as a single agent and in combination with other drugs.

Purpose To answer the question, “should elderly non–small-cell lung cancer patients be offered elderly-specific trials?” Patients and Methods The North Central Cancer Treatment Group (NCCTG) performed a pooled analysis of elderly patients who participated in elderly-specific trials (required age ≥ 65 years) and age-unspecified trials (required age ≥ 18 years). Between 1998 and 2000, all NCCTG non–small-cell lung cancer (NSCLC) patients with incurable cancer, age ≥ 65 years, and receiving first-line chemotherapy were included. A total of 118 elderly patients participated in elderly-specific trials, and 108, in age-unspecified trials. Demographics and outcomes were compared based on trial type. Results The median age of elderly patients in elderly-specific trials was greater: median (range): 73 years (65 to 87) and 70 years (65 to 85), respectively (P < .001), as was the percentage older than 80 years: 17% and 3%, respectively (P = .0008). Median survival times were 232 and 302 days, respectively (P = .08). After adjustment for baseline age, Eastern Cooperative Oncology Group performance score, cancer stage, and body mass index, this survival difference was not statistically significant (hazard ratio = 1.25; P = .16). Grade 3 or worse nonhematologic adverse event rates were greater in age-unspecified trials (81% v 57%, respectively; P < .001), as were grade 3 or worse hematologic events (68% v 10%, respectively; P < .001). Conclusion Elderly patients in NSCLC elderly-specific trials suffered lower rates of severe adverse events with no statistically significant differences in survival. It seems that elderly-specific trials are providing quality care and helping to define optimal cancer therapy in the elderly, particularly among the “oldest of the old.”