MOGN related AACR abstracts. I think I got them all.
abstractonline.com
Abstract Number: 602
Presentation Title:
Chromosome aberrations, DNA damage signaling and chemosensitivity induced by the anticancer agent, irofulven
Presentation Start/End Time:
Sunday, Apr 17, 2005, 8:00 AM -12:00 PM
Category:
ET06-05 Novel antitumor agents
Author Block:
Weixin Wang, Timothy Wiltshire, Yutian Wang, Sharon L. Wenger, Emily S. Van Laar, Stephen J. Waters, Eddie Reed. West Virginia University, Morgantown, WV, MGI-Pharma, Bloomington, MN
Irofulven (6-hydroxymethylacylfulvene) is one of a new class of anticancer agents that are semi-synthetic derivatives of the mushroom toxin illudin S. Preclinical studies and clinical trials have demonstrated that irofulven is effective against multiple tumor types. While mechanism of action studies suggest that irofulven induces DNA damage, ATM-dependent CHK2 activation, which contributes to S-phase arrest, and apoptosis, little is known regarding the nature and structure of DNA damage caused by irofulven. In this study, the chromosome damage and DNA damage response induced by irofulven, and the correlation between DNA damage signaling and chemosensitivity were investigated. In ovarian cancer cell lines A2780 (p53 wildtype) and CAOV3 (p53 mutant) cells irofulven induces chromosome breaks, triradials and quadriradials as demonstrated by mitotic spreads, suggesting irofulven induces DNA interstrand cross-linking and double strand breaks. Similar chromosome alterations were observed in paired colon cancer cell lines HCT116 and HCT116 p53-/- after irofulven treatment. The mitotic index was unchanged or decreased in all cells after irofulven treatment, indicating that irofulven-induced DNA damage results in cell cycle arrest. More chromosome radial formations and breaks were observed in CAOV3 and HCT116 p53-/- cells than in A2780 and HCT116 cells, suggesting that chromosome aberrations induced by irofulven are related to p53 status. Activation of DNA damage signaling proteins by irofulven induced DNA damage was explored in ovarian cancer cell lines. Phosphorylation of SMC1, NBS1, BRCA1 and p53 was observed after irofulven treatment. Furthermore, immunofluorescent staining indicated that 53BP1 and BRCA1 formed foci at the irofulven-induced damaged sites. To investigate whether the activation of DNA damage signaling proteins might contribute to chemosensitivity, vector and BRCA1-transfected human breast cancer cell line HCC1937, which lacks functional BRCA1, were treated with irofulven. As demonstrated by the colonogenic survival assay, BRCA1 expression conferred increased resistance to irofulven treatment. This observation was further corroborated by increased sensitivity to irofulven observed after knocking down the BRCA1 protein level by RNA interference in SKOV3 cells. In summary, these results indicate that irofulven induces chromosome aberrations and activates important effector proteins of DNA damage response pathways. Among them, BRCA1 contributes to irofulven-induced chemosensitivity. These findings may have clinical implications for irofulven-based therapy given the fact that BRCA1 is frequently mutated in familial breast and ovarian cancers. These observations also suggest that enhanced antitumor activity of irofulven can be achieved by targeted therapy against mediators of the DNA damage-signaling pathway.
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Abstract Number: 3310
Presentation Title:
The potential of irofulven to overcome chemo-resistance of hypoxic cells
Presentation Start/End Time:
Monday, Apr 18, 2005, 1:00 PM - 5:00 PM
Category:
ET02-02 Cell death pathways and treatment
Author Block:
Barbara A. Woynarowska, Adan Alvarez, Jan M. Woynarowski. UT Health Science Ctr., San Antonio, TX
Hypoxia is a critical factor limiting the efficacy of cancer chemo- and radio-therapy. The resistance of hypoxic cells is linked to hypoxia-stabilized HIF-1alpha, which mediates transcriptional activation of several survival genes, including pro-angiogenic VEGF. To be active, HIF-1 alpha needs to be reduced by the key redox regulating protein thioredoxin (Trx). Therefore agents interfering with the Trx function are expected to maintain activity under hypoxic conditions. The Trx system is among prominent protein targets for a novel antitumor drug irofulven (hydroxymethylacylfulvene), although the drug also forms monoadducts with DNA. This dual targeting has been linked to the consistently potent pro-apoptotic activity of irofulven in various models resistant to other pro-apoptotic stimuli. We hypothesized that by affecting the Trx system the drug might interfere with the transcriptional activation of HIF-1 and retain its activity against hypoxic cancer cells.
Here, we demonstrate that irofulven remains active under hypoxia. Prostate cancer LNCaP-Pro5 cells were essentially identically affected under hypoxic versus normoxic conditions, with 50% inhibition at 0.11 µM drug (as measured by MTT assay). The observed inactivation of the slowly proliferating hypoxic cells involved most likely direct loss of cell viability in addition to cell growth inhibition. Analogous loss of viability was observed in non-proliferating (contact inhibited) normoxic LNCaP-Pro5 cells but not in contact-inhibited normal NCM460 cells. Further experiments compared responses to irofulven in U251 glioma cells and its sublines established by Mellilo and co-workers (Cancer Res, 62: 4316-4324, 2002) harboring a luciferase reporter plasmid under the control of HIF-1a-dependent hypoxia responsive element (U251-HRE) and plasmid constitutively expressing luciferase (pGL3C). The ability of irofulven to inhibit the growth of each of these cell lines (MTT assay) was nearly identical under hypoxic versus normoxic conditions. For example, drug concentrations inhibiting the MTT signal by 50% (GI50) in wild type U251 cells amounted to 0.38±0.055 versus 0.45±0.005 µM, respectively. In U251-HRE, respective GI50 values were 0.62±0.15 and 0.64±.11 µM drug. Luciferase reporter assay confirmed the induction of HIF-1-mediated transcription in hypoxic control cells. Analogous determinations with irofulven-treated cells are in progress. Consistent with the possibility of impeded HIF-1 signaling, irofulven markedly reduced VEGF secretion in U251 cells. At 0.5-1 µM irofulven and exposure times of 24-48 h, the inhibition of VEGF secretion clearly preceded the overall inhibition of cell growth. The ability of irofulven to target and efficiently eradicate slowly proliferating and hypoxic cancer cells demonstrated by this study is relevant to the promising clinical properties of irofulven against solid tumors. (Supported by CA112175 and CA80936).
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Abstract Number: 3986
Presentation Title:
Pharmacokinetics, metabolism, and routes of excretion of intravenous [14C]-irofulven in patients with advanced solid tumors
Presentation Start/End Time:
Tuesday, Apr 19, 2005, 8:00 AM -12:00 PM
Category:
CL02-04 Pharmacokinetics
Author Block:
Francois Lokiec, Kevin Rezai, Pierre Bourgeois, G Ghanem, G Vassal, A Desroussent, Carmen Kahatt, Ajit K. Shah, Dominique De Valeriola. Centre Rene Huguenin, Saint Cloud, France, Jules Bordet Institute, Brussels, Belgium, IGR, Paris, France, Cvitkovic and Associes Consultants, Kremlin-Bicetre, France, MGI PHARMA INC, Bloomington, MN
Irofulven is a semi-synthetic derivative of the mushroom derived natural product illudin S that has demonstrated preclinical and clinical activity in a variety of tumor types. Pharmacokinetics, metabolism, and routes of excretion of [14C]-irofulven were evaluated in patients with advanced solid tumors. In this Phase I open label study, 3 patients (2 males and 1 female, 48-64 yr) received a dose of 0.55 mg/kg irofulven containing 100 µCi of [14C]-irofulven administered over a 30 min intravenous infusion on Day 1 of Cycle 1. Serial blood, plasma, urine, fecal, saliva, respiratory air, and tear samples were obtained up to 144 hr after the start of infusion. The plasma radioactivity declined with a distribution phase followed by a long elimination and was measurable up to 144 hr. In plasma, parent irofulven represented 0.2% of total radioactivity AUC(0-t). The Cmax (mean±SD) was 1130 ± 174 ng-eq/ml and 82.7±46.0 ng/ml for radioactivity and parent irofulven, respectively and occurred at Tmax of 0.72±0.12 and 0.29±0.1 hr, respectively. AUC(0-8), CLp, Vdss, and t½ for irofulven were 65.5±2.39 ng•hr/ml, 8.48±0.14 L/hr/kg, 3.12±1.99 L/kg, and 18±6 min, respectively. Blood to plasma AUC(0-t) ratio of radioactivity was 1.6±0.74 indicating little partitioning of irofulven-derived radioactivity into erythrocytes. Urinary excretion (71.2±9.6% of dose) was a major route of elimination of [14C]-irofulven equivalents and 2.9±2.4% of the radioactive dose was recovered in feces. Low levels of radioactivity were measurable in expired air and saliva. Metabolite profiling of urine samples indicated the presence of irofulven and seven metabolic products and two glucuronide conjugates. Plasma radioactivity profiling showed presence of two metabolites, none representing a major metabolite. The safety profile of irofulven was consistent with previous studies. No grade 4 hematotoxicity or biochemical abnormalities occurred. One patient experienced simultaneous grade 4 vomiting and dehydration (one episode of each). These results indicate that irofulven undergoes extensive metabolism and urinary excretion is the principal route of elimination of metabolites from the body.
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Abstract Number: 4986
Presentation Title:
Enhanced in vivo antitumor activity for the combination of irofulven and the antiangiogenic compounds, anginex or KM0118
Presentation Start/End Time:
Tuesday, Apr 19, 2005, 1:00 PM - 5:00 PM
Category:
ET01-02 Combination chemotherapy
Author Block:
Ruud P.M. Dings, Emily S. Van Laar, Stephen J. Waters, Jeremy G. Webber, John R. MacDonald, Kevin H. Mayo. University of Minnesota, Minneapolis, MN, MGI Pharma, Inc., Bloomington, MN
Anginex, a novel ß-sheet forming peptide 33-mer, and KM0118, a small molecule mimetic of anginex, have demonstrated preclinical ability to inhibit vascular endothelial cell proliferation and induce apoptosis via anoikis in vitro and to inhibit tumor growth in murine and human tumor xenograft models. Irofulven (6-hydroxymethylacylfulvene) is one of a new class of anticancer agents that are semi-synthetic derivatives of the mushroom natural product, illudin S, which has produced both preclinical and clinical evidence of antitumor activity. Because the clinical utility of combining antiangiogenic compounds and cytotoxic chemotherapy has now been demonstrated with other antiangiogenic compounds, we investigated the in vivo antitumor activity of anginex or KM0118 and irofulven in combination against the MA148 human ovarian carcinoma xenograft model. Initially, the antitumor activity of irofulven monotherapy was evaluated in this model at doses of 1.5, 3.0 and 4.5 (45% MTD) mg/kg administered by i.p. injection on a q3dx4 schedule. Dose-related activity was observed with 5/8 animals showing complete tumor regression (CR) at the 4.5 mg/kg dose, 2/8 partial responses (PR) with 83% tumor growth inhibition (TGI) at 3.0 mg/kg, and the 1.5 mg/kg dose producing 81% TGI. Based on these data, combinations of anginex or KM0118 (10 mg/kg administered s.c. for 28 days via osmotic minipump) and irofulven (1.5 mg/kg administered i.p. q3dx4) were evaluated against the MA148 xenograft model. Anginex produced 2/10 PR with 24% TGI, respectively; whereas, KM0118 produced 1/10 PR with 72% TGI. The anginex/irofulven combination showed enhanced antitumor activity compared to each agent alone demonstrating PR in 4/10 animals with 91% TGI. Likewise, the KM0118/irofulven combination also produced enhanced antitumor activity compared to each agent alone with 4/6 PR with 99% TGI. In a similar study using 10 mg/kg anginex administered i.p. q3dx4, 1/7 PR with 75% TGI was observed. The combination demonstrated 1/6 CR and 3/6 PR with 88% TGI. Each combination produced minimal toxicity as determined by body weight measurements over the course of the study. These data demonstrate significant antitumor activity of these antiangiogenic-cytotoxic chemotherapy combinations with negligible toxicity. |
