Efatutazone, an oral PPAR-γ agonist, in combination with paclitaxel in anaplastic thyroid cancer: results of a multicenter phase 1 trial.

PURPOSE: A phase 1 study was initiated to determine the safety, potential effectiveness, and maximal tolerated dose and recommended phase 2 dose of efatutazone and paclitaxel in anaplastic thyroid cancer. EXPERIMENTAL DESIGN: Patients received efatutazone (0.15, 0.3, or 0.5 mg) orally twice daily and then paclitaxel every 3 weeks. Patient tolerance and outcomes were assessed, as were serum efatutazone pharmacokinetics. RESULTS: Ten of 15 patients were women. Median age was 59 years. Seven patients received 0.15 mg of efatutazone, 6 patients received 0.3 mg, and 2 patients received 0.5 mg. One patient receiving 0.3 mg of efatutazone had a partial response from day 69 to day 175; 7 patients attained stable disease. Median times to progression were 48 and 68 days in patients receiving 0.15 mg of efatutazone and 0.3 mg of efatutazone, respectively; corresponding median survival was 98 vs 138 days. The median peak efatutazone blood level was 8.6 ng/mL for 0.15-mg dosing vs 22.0 ng/mL for 0.3-mg twice daily dosing. Ten patients had grade 3 or greater adverse events (Common Terminology Criteria for Adverse Events), with 2 of these (anemia and edema) related to efatutazone. Thirteen events of edema were reported in 8 patients, with 2 of grade 3 or greater. Eight patients had ≥1 serious adverse event, with 1 of these (anemia) attributed to efatutazone and 1 (anaphylactic reaction) related to paclitaxel. The maximal tolerated dose was not achieved. Angiopoietin-like 4 was induced by efatutazone in tissue biopsy samples of 2 patients. CONCLUSIONS: Efatutazone and paclitaxel in combination were safe and tolerated and had biologic activity.

The anticancer effects of chaetocin are independent of programmed cell death and hypoxia, and are associated with inhibition of endothelial cell proliferation.

BACKGROUND: We previously reported that chaetocin has potent and selective anti-myeloma activity attributable to reactive oxygen species (ROS) induction imposed by inhibition of the redox enzyme thioredoxin reductase; we now detail its effects in solid tumours. METHODS: Cellular assays, transcriptional profiling and the NCI60 screen were used to assess the effects of chaetocin in solid tumour and endothelial cells. RESULTS: NCI-60 screening demonstrated chaetocin to even more potently inhibit proliferation in solid tumour than in haematological cell lines; transcriptional profiling revealed a signature consistent with induction of inflammatory response and cell death pathways. Chaetocin induced ROS, oxidative damage to cellular proteins and apoptosis, with 2-10 nM IC(50)s (24 h exposures) in all tested solid tumour cell lines. The pan-caspase inhibitor zVAD-fmk did not block chaetocin-induced cell death despite inhibiting mitochondrial membrane depolarisation and apoptosis. Further, Molt-4 rho(0) cells lacking metabolically functional mitochondria were readily killed by chaetocin; in addition chaetocin-induced cytotoxicity was unaffected by autophagy inhibitors or hypoxia and consequent HIF-1α upregulation. Moreover, chaetocin inhibited SKOV3 ovarian cancer xenografts producing less vascular tumours, and inhibited human umbilical vein endothelial cell proliferation. CONCLUSION: Chaetocin has intriguing and wide-ranging in vitro and in vivo anticancer effects, and is an attractive candidate for further preclinical and clinical development.

Antitumor Activity of VB-111, a Novel Antiangiogenic Virotherapeutic, in Thyroid Cancer Xenograft Mouse Models.

VB-111 is an engineered antiangiogenic adenovirus that expresses Fas-c in angiogenic blood vessels and has previously been shown to have significant antitumor activity in vitro and in vivo in Lewis lung carcinoma, melanoma, and glioblastoma models. To evaluate the efficacy of VB-111 in thyroid cancer, we conducted in vivo xenograft nude mouse studies using multiple thyroid cancer-derived cell lines models. VB-111 treatment resulted in 26.6% (P = 0.0596), 34.4% (P = 0.0046), and 37.6% (P = 0.0249) inhibition of tumor growth in follicular, papillary and anaplastic thyroid cancer models, respectively. No toxicity was observed in any model. All tumor types showed a consistent and significant reduction of CD-31 staining (P < 0.05), reflecting a reduction of angiogenic activity in the tumors, consistent with the intended targeting of the virus. A phase 2 clinical trial of VB-111 in patients with advanced differentiated thyroid cancer is ongoing.

Effect of P-glycoprotein on flavopiridol sensitivity.

Flavopiridol is the first potent inhibitor of cyclin-dependent kinases (CDKs) to enter clinical trials. Little is known about mechanisms of resistance to this agent. In order to determine whether P-glycoprotein (Pgp) might play a role in flavopiridol resistance, we examined flavopiridol sensitivity in a pair of Chinese hamster ovary cell lines differing with respect to level of Pgp expression. The IC(50)s of flavopiridol in parental AuxB1 (lower Pgp) and colchicine-selected CH(R)C5 (higher Pgp) cells were 90.2 +/- 6.6 nM and 117 +/- 2.3 nM, respectively (P< 0.01), suggesting that Pgp might have a modest effect on flavopiridol action. Consistent with this hypothesis, pretreatment with either quinidine or verapamil (inhibitors of Pgp-mediated transport) sensitized CH(R)C5 cells to the antiproliferative effects of flavopiridol. Because of concern that colony forming assays might not accurately reflect cytotoxicity, we also examined flavopiridol-treated cells by trypan blue staining and flow cytometry. These assays confirmed that flavopiridol was less toxic to cells expressing higher levels of Pgp. Further experiments revealed that flavopiridol inhibited the binding of [3H]-azidopine to Pgp in isolated membrane vesicles, but only at high concentrations. Collectively, these results identify flavopiridol as a weak substrate for Pgp.

Loss of expression of a new member of the DNAJ protein family confers resistance to chemotherapeutic agents used in the treatment of ovarian cancer.

Differential display-PCR between ovarian tumor cell lines and short-term cultures of normal ovarian epithelial cell brushings was used to isolate a differentially expressed transcript and its corresponding gene. The gene, which mapped to 13q14.1, has partial homology in the DNAJ domain to a number of proteins with a similar domain and was designated as methylation-controlled J protein (MCJ). MCJ has the highest similarity to a functionally undefined protein from Caenorhabditis elegans. MCJ is expressed as a 1.2-kb transcript in several adult tissues, with testis showing the highest level of expression. Expression of MCJ was absent in three of seven ovarian cancer cell lines. Similarly, expression analysis using semiquantitative reverse transcription-PCR indicated that 12 of 18 primary ovarian tumors examined had either a complete absence or lower levels of expression of this gene. 5-Aza-2'-deoxycytidine treatment of the OV202 cell line induced MCJ expression in a dose-dependent manner, implicating methylation in this induction. Loss of heterozygosity and methylation-specific PCR analysis revealed that the loss of MCJ expression in primary tumors and cell lines was attributable to deletion of one allele and methylation of the other. To assess the potential functional significance of MCJ down-regulation, the sensitivity of parental (MCJ-nonexpressing) and MCJ-transfected OV167 cells to antineoplastic agents was evaluated. MCJ expression was associated with enhanced sensitivity to paclitaxel, topotecan, and cisplatin, suggesting that MCJ loss may play a role in de novo chemoresistance in ovarian carcinoma. These observations raise the possibility that MCJ loss may: (a) have potential prognostic significance in ovarian cancer; and (b) contribute to the malignant phenotype by conferring resistance to the most commonly used chemotherapeutic agents for ovarian cancer.

The HER tyrosine kinase inhibitor CI1033 enhances cytotoxicity of 7-ethyl-10-hydroxycamptothecin and topotecan by inhibiting breast cancer resistance protein-mediated drug efflux.

Because the activities of HER family members are elevated and/or aberrant in a variety of human neoplasms, these cell surface receptors are receiving increasing attention as potential therapeutic targets. In the present study, we examined the effect of combining the HER family tyrosine kinase inhibitor CI1033 (PD 183805) with the topoisomerase (topo) I poison 7-ethyl-10-hydroxycamptothecin (SN-38), the active metabolite of irinotecan, in a number of different cell lines. Colony-forming assays revealed that the antiproliferative effects of simultaneous treatment with CI1033 and SN-38 were synergistic in T98G glioblastoma cells and HCT8 colorectal carcinoma cells, whereas sequential treatments were additive at best. In additional studies examining the mechanistic basis for these findings in T98G cells, immunoblotting revealed that the inhibitory effects of CI1033 on epidermal growth factor receptor autophosphorylation were unaffected by SN-38. Likewise, CI1033 had no effect on topo I polypeptide levels, localization, or activity. Nonetheless, CI1033 markedly enhanced the number of covalent topo I-DNA complexes stabilized by SN-38 or the related agent topotecan (TPT). Analysis of intracellular SN-38 levels by high-performance liquid chromatography and intracellular TPT levels by flow microfluorometry revealed that CI1033 increased the steady-state accumulation of SN-38 and TPT by 9.4 +/- 1.9- and 1.8 +/- 0.2-fold, respectively. Further evaluation revealed that the initial rate of TPT uptake was unaffected by CI1033, whereas the rate of efflux was markedly diminished. Additional studies demonstrated that T98G and HCT8 cells express the breast cancer resistance protein (BCRP), a recently cloned ATP binding cassette transporter. Moreover, CI1033 enhanced the uptake and cytotoxicity of SN-38 and TPT in cells transfected with BCRP but not empty vector. Conversely, CI1033 accumulation was diminished in cells expressing BCRP, suggesting that CI1033 is a substrate for this efflux pump. These results indicate that CI1033 can modulate the accumulation and subsequent cytotoxicity of two widely used topo I poisons in cells that have no history of previous exposure to these agents.

Flavopiridol binds to duplex DNA.

Flavopiridol, the first potent cyclin-dependent kinase inhibitor to enter clinical trials, was recently found to be cytotoxic to noncycling cells. The present studies were performed to examine the hypothesis that flavopiridol, like several other antineoplastic agents that kill noncycling cells, might also interact with DNA. Consistent with this possibility, treatment of A549 human lung cancer cells with clinically achievable concentrations of flavopiridol resulted in rapid elevations of the DNA damage-responsive protein p53. In further studies, the binding of flavopiridol to DNA was examined in vitro by four independent techniques. Absorption spectroscopy revealed that addition of DNA to aqueous flavopiridol solutions resulted in a red shift of the flavopiridol lambda(max) from 311 to 344 nm, demonstrating an isosbestic point typical of changes seen with DNA-binding compounds. Reverse-phase high-performance liquid chromatography demonstrated that flavopiridol binds to genomic DNA to a similar extent as ethidium bromide and Hoechst 33258. Nuclear magnetic resonance spectroscopy revealed that DNA caused extreme broadening of flavopiridol 1H nuclear magnetic resonance signals that could be reversed by addition of ethidium bromide or by DNA melting, suggesting that flavopiridol binds to (and likely intercalates into) duplex DNA. Equilibrium dialysis demonstrated that the equilibrium dissociation constant of the flavopiridol-DNA complex (5.4+/-3.4 x 10(-4) M) was in the same range observed for binding of the intercalators doxorubicin and pyrazoloacridine to DNA. Molecular modeling confirmed the feasibility of flavopiridol intercalation into DNA and analysis of the effects of flavopiridol in the National Cancer Institute tumor cell line panel using the COMPARE algorithm demonstrated that flavopiridol most closely resembles cytotoxic antineoplastic intercalators. Collectively, these data suggest that DNA might be a second target of flavopiridol, providing a potential explanation for the ability of this agent to kill noncycling cancer cells.

Characterization of an ovarian carcinoma cell line resistant to cisplatin and flavopiridol.

Flavopiridol, the first inhibitor of cyclin-dependent kinases to enter clinical trials, has shown promising antineoplastic activity and is currently undergoing Phase II testing. Little is known about mechanisms of resistance to this agent. In the present study, we have characterized an ovarian carcinoma cell line [OV202 high passage (hp)] that spontaneously developed drug resistance upon prolonged passage in tissue culture. Standard cytogenetic analysis and spectral karyotyping revealed that OV202 hp and the parental low passage line OV202 shared several marker chromosomes, confirming the relatedness of these cell lines. Immunoblotting demonstrated that OV202 and OV202 hp contained similar levels of a variety of polypeptides involved in cell cycle regulation, including cyclin-dependent kinases 2 and 4; cyclins A, D1, and E; and proliferating cell nuclear antigen. Despite these similarities, OV202 hp was resistant to flavopiridol and cisplatin, with increases of 5- and 3-fold, respectively, in the mean drug concentrations required to inhibit colony formation by 90%. In contrast, OV202 hp and OV202 displayed indistinguishable sensitivities to oxaliplatin, paclitaxel, topotecan, 1,3-bis(2-chloroethyl)-1-nitrosourea, etoposide, doxorubicin, vincristine, and 5-fluorouracil, suggesting that the spontaneously acquired resistance was not attributable to altered P-glycoprotein levels or a general failure to engage the cell death machinery. After incubation with cisplatin, whole cell platinum and platinum-DNA adducts measured using mass spectrometry were lower in OV202 hp cells than OV202 cells. Similarly, after flavopiridol exposure, whole cell flavopiridol concentrations measured by a newly developed high performance liquid chromatography assay were lower in OV202 hp cells. These data are consistent with the hypothesis that acquisition of spontaneous resistance to flavopiridol and cisplatin in OV202 hp cells is due, at least in part, to reduced accumulation of the respective drugs. These observations not only provide the first characterization of a flavopiridol-resistant cell line but also raise the possibility that alterations in drug accumulation might be important in determining sensitivity to this agent.

Characterization of caspase processing and activation in HL-60 cell cytosol under cell-free conditions. Nucleotide requirement and inhibitor profile.

The present studies compared caspase activation under cell-free conditions in vitro and in etoposide-treated HL-60 leukemia cells in situ. Immunoblotting revealed that incubation of HL-60 cytosol at 30 degrees C in the presence of cytochrome c and ATP (or dATP) resulted in activation of procaspases-3, -6, and -7 but not -2 and -8. Although similar selectivity was observed in intact cells, affinity labeling revealed that the active caspase species generated in vitro and in situ differed in charge and abundance. ATP and dATP levels in intact HL-60 cells were higher than required for caspase activation in vitro and did not change before caspase activation in situ. Replacement of ATP with the poorly hydrolyzable analogs 5'-adenylyl methylenediphosphate, 5'-adenylyl imidodiphosphate, or 5'-adenylyl-O-(3-thiotriphos-phate) slowed caspase activation in vitro, suggesting that ATP hydrolysis is required. Caspase activation in vitro was insensitive to phosphatase and kinase inhibitors (okadaic acid, staurosporine, and genistein) but was inhibited by Zn(2+), aurintricarboxylic acid, and various protease inhibitors, including 3,4-dichloroisocoumarin, N(alpha)-p-tosyl-L-phenylalanine chloromethyl ketone, N(alpha)-p-tosyl-L-lysine chloromethyl ketone, and N-(N(alpha)-benzyloxycarbonylphenylalanyl)alanine fluoromethyl ketone, each of which inhibited recombinant caspases-3, -6, -7, and -9. Experiments with anti-neoepitope antiserum confirmed that these agents inhibited caspase-9 activation. Collectively, these results suggest that caspase-9 activation requires nucleotide hydrolysis and is inhibited by agents previously thought to affect apoptosis by other means.

A one-step method for protein estimation in biological samples: nitration of tyrosine in nitric acid.

A number of methods are commonly employed for the determination of protein in biological samples. Unfortunately, several compounds that are constituents of biological buffers interfere with these methods, limiting their application. Previous studies have demonstrated that tyrosine rapidly undergoes nitration in nitric acid to yield 3-nitrotyrosine, which has a lambdamax of 358 nm. Utilizing this reaction, we have developed a one-step method for the assessment of protein content in biological samples. Common interfering substances, including SDS, urea, glycerol, ammonium sulfate, and beta-mercaptoethanol, do not interfere with this method. Because of its simplicity, this reaction might be useful for estimating protein content in a variety of biological samples.

Cytotoxic synergy between flavopiridol (NSC 649890, L86-8275) and various antineoplastic agents: the importance of sequence of administration.

Flavopiridol, the first potent cyclin-dependent kinase inhibitor to undergo clinical trials as an antineoplastic agent in the United States, has attracted considerable attention because of its unique cellular targets and its ability to kill noncycling tumor cells in vitro. To better understand how flavopiridol might be used clinically, the present study used colony-forming assays to examine the cytotoxicity resulting from combining flavopiridol with eight other antineoplastic agents in four different administration schedules in A549 human non-small cell lung carcinoma cells in vitro. Cytotoxic synergy, as assessed by the median effect method, resulted when flavopiridol was combined with seven of the eight tested antineoplastic agents but was highly dependent upon administration schedule. Cisplatin was the only agent that resulted in sequence-independent synergy when combined with flavopiridol. For paclitaxel, cytarabine, topotecan, doxorubicin, and etoposide, synergy was more pronounced when the agents were administered before flavopiridol rather than concomitant with or following flavopiridol. Examination suggested that this sequence dependence reflected arrest of cells in G1 and G2 phases of the cell cycle during and for 24 h following flavopiridol treatment. Interestingly, 48-72 h after flavopiridol removal, the fraction of surviving cells in S phase increased 2-3-fold relative to untreated controls. Consistent with these results, administration of flavopiridol for 24 h followed 3 days later by exposure to an S phase-active agent (cytarabine or 5-fluorouracil) resulted in a highly synergistic interaction. These results highlight the importance of administration schedule when combining flavopiridol with other agents and provide a starting point for examining the effect of flavopiridol in drug combinations in vivo.

Flavopiridol: a cytotoxic flavone that induces cell death in noncycling A549 human lung carcinoma cells.

Flavopiridol (NSC 649890, L86-8275), a potent inhibitor of cyclin-dependent kinase 1/p34cdc2 phosphorylation and kinase activity, is currently undergoing Phase I clinical testing as a potential antineoplastic agent. Previous studies have suggested that flavopiridol is cytostatic but not cytotoxic when applied to exponentially growing cells. In the present study, various human tumor cell lines were assayed for trypan blue exclusion and ability to form colonies after exposure to flavopiridol under a variety of growth conditions. When log phase A549 non-small cell lung cancer cells were examined 72 h after the start of a 24-h flavopiridol exposure, as many as 90% of the cells accumulated trypan blue. A 24-h exposure to 250-300 nM resulted in trypan blue uptake in 50% of A549 cells at 72 h and a 50% reduction in colony formation. Similar results were observed in HCT8 ileocecal adenocarcinoma, T98G glioblastoma, MCF-7 breast adenocarcinoma, and HL-60 leukemia cells. With A549 cells, identical results were obtained in actively growing logarithmic phase cells and growth-arrested confluent cells. Treatment with the DNA synthesis inhibitor aphidicolin only minimally affected the cytotoxicity of flavopiridol. In contrast, the RNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole or the protein synthesis inhibitor cycloheximide reduced the cytotoxicity of flavopiridol. These results suggest that: (a) flavopiridol is not only cytostatic, but also cytotoxic to a variety of human tumor cell lines; (b) flavopiridol is equally active against cycling and noncycling A549 cells; and (c) RNA and protein synthesis appear to play a role in flavopiridol-induced cytotoxicity.

Acyl tunichlorins: a new class of nickel chlorins isolated from the Caribbean tunicate Trididemnum solidum.

A new class of nickel-containing chlorins (acyl tunichlorins) has been isolated from the Caribbean tunicate Trididemnum solidum. The structures of 28 of these nickel (II) hydroporphyrins were elucidated using mass spectrometry, one- and two-dimensional NMR spectroscopy, and chemical degradation/derivatization. Unique structural features of these compounds include the diversity of aliphatic side chains, which are derived from C14:0 to C22:6 fatty acids, and their location at an unprecedented position at C-2a on the hydroporphyrin nucleus. No chlorins with ester-linked acyl side chains at C-2a have been reported previously. Although the exact biological role that these compounds play in T. solidum remains unknown, acyl tunichlorins represent the only nickel-containing chlorins to be isolated from a living system and are the C-2a acyl derivatives of tunichlorin, a nickel chlorin reported by this laboratory in 1988.

Cyclosporine A alleviates severe anaemia associated with refractory large granular lymphocytic leukaemia and chronic natural killer cell lymphocytosis.

Large granular lymphocytic (LGL) leukaemia and chronic natural killer cell lymphocytosis (CNKL) are chronic indolent disorders often associated with neutropenia and constitutional symptoms. Severe anaemia occurs in about 20% of patients and is currently treated with corticosteroids followed by oral cyclophosphamide in non-responders. 30% of patients fail initial measures, and salvage therapy is inadequate. We describe three transfusion-dependent patients (two with T-LGL leukaemia, one with CNKL) refractory to corticosteroids, cyclophosphamide, and in one case fludarabine. Cyclosporine A (CSA) initiation resulted in prompt transfusion-independence and was well tolerated in all patients, making it an attractive alternative therapy for this disorder.

Tunichlorin: a nickel chlorin isolated from the Caribbean tunicate Trididemnum solidum.

Tunichlorin, a blue-green pigment isolated from the Caribbean tunicate Trididemnum solidum, has been identified as nickel(II) 2-devinyl-2-hydroxymethylpyropheophorbide a by chemical and spectroscopic methods, with confirmation by partial synthesis of dimethyl tunichlorin from chlorophyll a. Nickel chlorins have been reported from geological sources but not from living organisms. Its occurrence in a living system suggests a metabolic role for tunichlorin and may clarify the selective accumulation of nickel by marine tunicates. Because Trididemnum tunicates are associated with algal symbionts, tunichlorin may arise directly from the tunicate, from symbiotic algae, or from tunicate modification of an algal chlorin.

Didemnins and tunichlorin: novel natural products from the marine tunicate Trididemnum solidum.

Didemnins A, B, and C, cyclic depsipeptides previously reported by our laboratory from the Caribbean tunicate Trididemnum solidum, have now been synthesized and, in the process, their structures have been revised to include the new amino acid (3S,4R,5S)-isostatine,C2H5CH(CH3)CHNH2CHOHCH2COOH. All other isomers of isostatine have also been prepared. Didemnin B is currently in Phase II clinical trials as an anticancer agent, and the antineoplastic activity, as well as the antiviral and immunosuppressive activities, of the didemnins are reviewed. A highly unusual porphynoid has also been isolated from T. solidum. The compound has been named tunichlorin and is apparently the first nickel-containing chlorin (and only the second nickel-containing porphyrin-related compound) identified from a living organism.

Gastric ulceration as a complication of hepatic artery infusion chemotherapy.

Based upon the cases reported in this paper and upon a literature review encompassing 1,783 patients having received HAIC, it is our opinion that upper gastrointestinal tract ulceration is a potentially significant complication of hepatic artery infusion chemotherapy. In addition, we believe that the mechanism responsible for HAIC-induced ulceration often involves direct perfusion of the gastric arterial supply with chemotherapeutic agents. The occurrence of ulcerations in patients with surgically placed catheters is disconcerting, and does not allow for any apparent easy method of alleviating HAIC-induced ulceration. Clinicians should be alerted to the possibility of gastric and duodenal ulceration in patients treated with HAIC, and should afford particular attention to gastrointestinal symptoms during hepatic artery infusion chemotherapy.