UC Irvine Chao Family Comprehensive Cancer Center

A vailable tyrosine kinase inhibitors for chronic myeloid leukemia bind in an adenosine 5′-triphosphate-binding pocket and are affected by evolving mutations that confer resistance. Rebastinib was identified as a switch control inhibitor of BCR-ABL1 and FLT3 and may be active against resistant mutations. A Phase 1, first-in-human, single-agent study investigated rebastinib in relapsed or refractory chronic or acute myeloid leukemia. The primary objectives were to investigate the safety of rebastinib and establish the maximum tolerated dose and recommended Phase 2 dose. Fifty-seven patients received treatment with rebastinib. Sixteen patients were treated using powder-in-capsule preparations at doses from 57 mg to 1200 mg daily, and 41 received tablet preparations at doses of 100 mg to 400 mg daily. Dose-limiting toxicities were dysarthria, muscle weakness, and peripheral neuropathy. The maximum tolerated dose was 150 mg tablets administered twice daily. Rebastinib was rapidly absorbed. Bioavailability was 3- to 4-fold greater with formulated tablets compared to unformulated capsules. Eight complete hematologic responses were achieved in 40 evaluable chronic myeloid leukemia patients, 4 of which had a T315I mutation. None of the 5 patients with acute myeloid leukemia responded. Pharmacodynamic analysis showed inhibition of phosphorylation of substrates of BCR-ABL1 or FLT3 by rebastinib. Although clinical activity was observed, clinical benefit was insufficient to justify continued development in chronic or acute myeloid leukemia. Pharmacodynamic analyses suggest that other kinases inhibited by rebastinib, such as TIE2, may be more relevant targets for the clinical development of rebastinib (clinicaltrials.gov Identifier:00827138).

Abstract Introduction: Epidemiologic observations have suggested a protective effect of soybeans against a number of epithelial cancers including oral malignancies and by inference precursor lesions such as leukoplakia. Several compounds in soybeans have shown activity in preclinical models; we have focused our studies on BBI (Bowman-Birk inhibitor), which is active against the protease chymotrypsin. Our phase I trial demonstrated a very low toxicity profile and a 31% response rate in a 1-month nonrandomized study that was associated with favorable modulation of protease activity and neu oncogene in exfoliated buccal mucosal cells (EBMC). Methods: An intent-to-treat(ITT) randomized placebo (Quaker mass harina, a corn flour)-controlled, double-blind clinical trial of a soybean concentrate (C) of BBI (600 C.I. units) was performed in a multinstitutional investigation (7 sites). The study duration was 6 months and included pre/interim/postevaluation of lesions sizes and pre/post photographic assessments and oral mucosa biopsies(with post central pathology review) of the involved area(s). Intermediate biomarkers (IBM) included serial measurements of EBMC neu protein (ng/mg) and protease (Delrfu/min/ug protein) and serum neu protein (ng/ml). 325 patients underwent preliminary screening and 148 per protocol eligible were enrolled. Of these, 132 were randomized and 105 completed 6 months on study. All data on lesion sizes, photo judgments, and pathology indications of degree of abnormality or change in abnormality were entered into SAS datasets and subjected to 100% verification against the crf forms by the statistician. The several IBM measurements were converted from the original Microsoft Excel sheets into SAS data sets, and subject to spot checks against the original spreadsheets. Similarly, host-factor information from the questionnaires was spot checked against the original records. In all cases, the primary, per-protocol analyses was ITT. The per-protocol, intent-to-treat cohort, and all other categorizations of study participants will also be described with appropriate descriptive summary measures. Results: The ITT data set is composed of all those with valid, two-dimensional measurements on all lesions observed at both the randomization and 6-month visit. 89 evaluable patients met these criteria: 43 in the treatment and 46 in the placebo group. For the BBIC group, the mean relative percent change in total lesion area was −20.6% and for the placebo group −17.1%. Clinical responses for the 89 patients were: four showed a complete response (4.5%), 22 showed a partial response (25%), 53 showed stable disease (60%), and 10 showed disease progression (11.2%). For the drug group the CR+PR(>50% change) was 27.91% and for placebo group 30.43%. Neither the lesion size nor response comparisons demonstrated differences between the two groups that were significantly different (p>0.05). Photos of the same lesion at baseline and at the 6-month exam were available for 91 participants. Five qualified reviewers made judgments of the degree of change in abnormality on a seven-point scale, blinded to study arm and timepoint of photos. For mean comparison scores, 1 was substantial improvement over time, 4 indicated no change and 7 meaning much worse decline over time. Preliminary assessments of 77% of the patients having pre/post photos indicates that there were no significant differences between the placebo and treatment groups. Conclusion: BBIC is not effective as a chemoprevention agent for the management of oral leukoplakia. Central pathology review by two reviewers is near completion, but is unlikely to affect this conclusion. Final measurements of the three biomarkers should be available by the time of presentation and subanalysis will be presented for the two groups and for the patients who seemed to have had a clinical response. Citation Information: Cancer Prev Res 2010;3(12 Suppl):CN02-05.

ABSTRACT Activating mutations in KRAS extensively reprogram cellular metabolism to support the continuous growth, proliferation, and survival of pancreatic tumors. Targeting these metabolic dependencies are promising approaches for the treatment of established tumors. However, metabolic reprogramming is required early during tumorigenesis to provide transformed cells selective advantage towards malignancy. Acinar cells can give rise to pancreatic tumors through acinar-to-ductal metaplasia (ADM). Dysregulation of pathways that maintain acinar homeostasis accelerate tumorigenesis. During ADM, acinar cells transdifferentiate to duct-like cells, a process driven by oncogenic KRAS . The metabolic reprogramming that is required for the transdifferentiation in ADM is unclear. We performed transcriptomic analysis on mouse acinar cells undergoing ADM and found metabolic programs are globally enhanced, consistent with the transition of a specialized cell to a less differentiated phenotype with proliferative potential. Indeed, we and others have demonstrated how inhibiting metabolic pathways necessary for ADM can prevent transdifferentiation and tumorigenesis. Here, we also find NRF2-target genes are differentially expressed during ADM. Among these, we focused on the increase in the gene coding for NADPH-producing enzyme, Glucose-6-phosphate dehydrogenase (G6PD). Using established mouse models of Kras G12D -driven pancreatic tumorigenesis and G6PD-deficiency, we find that mutant G6pd accelerates ADM and pancreatic intraepithelial neoplasia. Acceleration of cancer initiation with G6PD-deficiency is dependent on its NADPH-generating function in reactive oxygen species (ROS) management, as opposed to other outputs of the pentose phosphate pathway. Together, this work provides new insights into the function of metabolic pathways during early tumorigenesis.

Abstract Background: Wnt signaling is involved in many events including embryogenesis, stem cell regulation, morphogenesis, cell fate determination, and oncogenesis. The role of Wnt pathway in angiogenesis is proposed, however the mechanism is still unclear. Most cancers express elevated levels of different Wnts when compared to normal cells. LEF-1 is a participant in and a target gene of the Wnt/ -catenin pathway. LEF-1 increases the in vitro invasiveness of cancer cells. Hypothesis: We suggest that LEF-1 controls the invasion also in endothelial cells. We hypothesize further that cancer affects local tumor angiogenesis via Wnt pathway-dependent up-regulation of LEF-1 in endothelial cells (EC). Methods: To test this hypothesis we construct a model system: endothelial cell line EaHy926 treated with Wnt3a (mostly known as a canonical Wnt signal) conditioned medium or grown in co-culture with L-cells producing Wnt3a. Results: Wnt3a increases nuclear ß-catenin in human endothelial cell line, and up-regulates LEF/TCF-dependent promoter activity. Wnt3a augments its target gene's LEF-1 promoter activity and LEF-1 mRNA concentration, demonstrating involvement of some transcription factors with E-tails. Both Wnt3a treatment and LEF-1 overexpression elevate MMP-2 mRNA level. Elimination of Wnt-dependent induction of MMP-2 gene expression by LEF-1 siRNA confirms the LEF-1 role in the MMP-2 control mechanism. Loosening up the extracellular matrix MMPs allows the cells to move around. These enzymes are integral part of invasion process. Indeed, LEF-1 up-regulates endothelial cells invasiveness in Matrigel matrix. LEF-1 increases also EC proliferation, in agreement with published data for parental primary endothelial culture HUVEC. Conclusions: In endothelial cells canonical (ß-catenin) Wnt signaling enhances invasiveness of EC via LEF-1 - dependent regulation of MMP-2 expression. There is a number of similarities between primary cells HUVEC, studied by others, and cell line EAhy926 in their response to Wnt3a. This indicates that EAhy926 cell line conserves many components of angiogenesis control by Wnt/β-catenin pathway and could serve as a simplified model to study this regulation, replacing primary endothelial cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-367.