Citations

Context.— Lung cancer is the number one cause of cancer deaths in the United States and globally. The advent of targeted therapies has offered a new treatment paradigm for lung cancer, but currently validated and emerging drugs are effective in only a small minority of lung cancers, predominantly adenocarcinomas. Folate receptors can serve as targets for drugs attached to folate and are overexpressed in many cancers. Objective.— To determine the frequency of folate receptor overexpression in lung cancers of different cell types as potential targets for folate-linked therapy. Design.— High-density tissue microarrays were constructed from archival formalin-fixed, paraffin-embedded resection specimens from 188 primary stage I or stage II adenocarcinomas or squamous cell carcinomas of the lung with three 0.1-cm cores from each tumor. Tissue microarrays were immunostained for folate receptor α with mAb343 and the results scored (0 to 1+ = weak expression, 2+ to 3+ = strong expression). Results.— Eighty-four of 117 (72%) of the adenocarcinomas were strongly positive for the folate receptor, and 36 of 71 (51%) of the squamous cell carcinomas were strongly positive for the folate receptor. Conclusions.— Our data indicate that a large percentage of lung cancers, including squamous cell carcinomas in addition to adenocarcinomas, strongly express folate receptor. This suggests that folate-linked targeted therapy can potentially be used to treat the majority of lung cancers, both adenocarcinomas and, particularly, squamous cell carcinomas, that do not respond to current targeted therapies.

Abstract Introduction: Invasive transitional cell carcinoma of the urinary bladder (InvTCC) kills >14,000 people yearly in the US. Folate receptors (FRs, especially FRα) are being targeted for imaging and therapy across multiple cancer types. This work was performed to define FR expression and uptake in InvTCC, with comparison to normal bladder; and to determine the antitumor activity and toxicity of folate-targeted vinblastine in dogs with naturally-occurring InvTCC where the cancer closely mimics human InvTCC. Canine InvTCC metastasizes frequently, and only 35% of dogs have remission with chemotherapy. Methods: Immunohistochemistry (IHC, mab343, PU17, FRβmab) was performed in InvTCC, bladder tissues adjacent to InvTCC in humans, and in bladder from normal dogs. Folate uptake was determined ex vivo by folate binding assay, and in vivo in dogs with InvTCC by nuclear scintigraphy (99mTc based FR targeted imaging agent). A dose escalation study of folate-targeted vinblastine (EC0905, IV weekly) was performed in dogs with biopsy-confirmed, FR-positive, measurable InvTCC. Toxicity (VCOG criteria) was assessed by CBCs, serum chemistry profiles, urinalyses, physical exams, and dog owner observations. The MTD was defined as the highest dose at which 0 of 6 dogs had grade 4 toxicity and ≤1 of 6 dogs had grade 3 toxicity. Tumor response was assessed by ultrasonography (with detailed bladder mapping) and radiography. Results: FR expression (IHC, PU17) was noted in the majority of canine samples including 56 of 74 (76%) primary tumors, 7 of 12 (58%) nodal metastases, and 10 of 21 (48%) lung metastases, as well as in normal urothelium. Typically, >50% of tumor cells were positive. FR expression was cytoplasmic in 18, membrane in 6, and in both sites in 32 InvTCC cases. Scintigraphy (n= 12 dogs) revealed folate uptake in primary and metastatic lesions. The MTD of EC0905 in dogs was 0.25 mg/kg IV weekly. At doses above the MTD, gastrointestinal upset and myelosuppression occurred. No urologic toxicity was noted. Tumor responses included partial remission (≥50% reduction in tumor volume) in 5 dogs and stable disease (<50% change in tumor volume) in 5 dogs. In human InvTCC, IHC results with PU17 were similar to those in dogs with 29 of 36 (78%) primary tumors, 12 of 15 (80%) nodal metastases, and 5 of 5 tissues adjacent to InvTCC being positive. Immunoreactivity to mab343 was less frequent (22% of primary tumors, 33% of nodal metastases). FRβ was expressed in 3 of 14 (21%) InvTCC cases. Ex vivo folate binding to human and canine InvTCC was detected, although binding varied from case to case and did not always correlate with IHC. Conclusions: Folate-targeted therapy holds promise for the treatment of InvTCC. FR expression was detected in human and canine InvTCC, and folate-targeted vinblastine had excellent antitumor activity against canine InvTCC where the cancer closely mimics human InvTCC. In addition to FRα, FRβ may be important in InvTCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-5. doi:1538-7445.AM2012-LB-5

Abstract Poly (ADP-ribose) polymerase (PARP) inhibition can enhance the efficacy of temozolomide (TMZ) and has been shown to significantly prolong survival in orthotopic GBM xenografts. Here the effects of PARP inhibitor AG014699 (AG699) on the efficacy of TMZ was evaluated and corresponding pharmacokinetic and pharmacodynamic studies were performed in the MGMT methylated GBM12 primary GBM xenograft line. AG699 effectively sensitized GBM12 cells to TMZ in vitro in a neurosphere formation assay: IC50 of 1.56 M for TMZ when combined with 1 μM AG699 compared to 8.16 M TMZ when used alone). Using these same cells, orthotopic xenografts were established and mice were randomized to 3–28 day cycles of placebo or TMZ (50 mg/kg days 1–5) with or without AG699 (1 mg/kg IP days 1–5). Although this model is responsive to other TMZ/PARP inhibitor combinations, the addition of AG699 was ineffective (median survival: placebo 16 days, TMZ 68 days and TMZ/AG699 81 days, p=0.883). In contrast, AG699 significantly potentiated TMZ-induced tumor regrowth delay in a flank tumor model with GBM12 (median time for tumors to reach endpoint: placebo 32 days, TMZ 86 days and TMZ/AG699 121 days, p<0.01). To more clearly understand the discrepancy between intracranial and flank studies, drug accumulation and target inhibition were assessed. Plasma and tissue distribution studies in mice bearing GBM12 orthotopic xenografts showed that 0.5 h after AG699 treatment its level in brain and tumor xenograft was much lower compared with that in liver (see table). In an assessment of catalytic activity, PARP activity in liver was inhibited more than 95% of control at least 2 h after AG699 treatment, while it was inhibited less than 50% and 30% in orthotopic xenograft tissue and normal brain, respectively (Table). Collectively, these data support the hypothesis that the efficacy of AG699 combined with TMZ is limited in the orthotopic model due to limited drug accumulation within the brain, and the mechanisms of which are under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A77.

Abstract Glioblastoma multiforme (GBM) is the most common and highly malignant primary brain tumor in adults with a median survival just over 1 year, and novel therapies are urgently needed. Deregulation of the p16 (INK4A)-CDK4/6-pRb pathway are commonly found in human GBM patients and selective inhibitors of CDK4/6 may be specifically useful to suppress proliferation associated with these alterations. PD0332991 is an orally active small molecule that specifically inhibits CDK4 and CDK6. Therefore, the efficacy of PD0332991 was evaluated in the Mayo panel of primary GBM xenograft lines using short-term explant cultures. We hypothesized that expression of p15 and/or p16, endogenous inhibitors of CDK4/6 activity, would suppress the response of GBM tumors to PD0332991 treatment. To test this hypothesis, 2 GBM xenograft cell lines with wild-type p16/p15 levels (GBM5 and 28) and 2 lines without detectable p16/p15 levels (GBM22 and 43) were selected for further analysis. Tumor cells were treated with graded concentrations (10 nanoM to1 microM) of PD0332991 for 5 days and subjected to CyQUANT cell proliferation assays. Consistent with our hypothesis, treatment with 1 microM PD0332991 effectively inhibited cell proliferation to 56.6±3.5% (P<0.001) and 44.3±3.4% (P<0.001) of control in GBM22 and GBM43 cells respectively, but did not affect cell proliferation in GBM5 and GBM28 cells (98.7±15.6% and 101.8±12.0% of control, respectively). In addition, 1 microM PD0332991 induced G1-phase cell cycle arrest in GBM22 (treated 79.7±0.8% vs. control 63.4±0.5% of cells in G1 phase, P<0.001) and GBM43 (treated 70.6±1.1% vs. control 48.9±4.6% of cells in G1 phase, P<0.001) but not in GBM5 and GBM28 (treated 52.3±2.7% vs. control 54.0±5.1%, treated 52.4±4.7% vs. control 54.6±2.6%, respectively). The status of p15 and p16 was confirmed by RT-PCR, which demonstrated readily detectable expression of p15 and p16 in GBM5 and GBM28, but not in GBM22 and GBM43 cells. Additional comparative genomic hybridization (CGH) data showed that CDKN2A and 2B (genes encode for p16 and p15 respectively) are homozygously deleted in GBM22 and 43, hemizygously deleted in GBM5 and normal in GBM28. We also examined the status of CDK4, CDK6, pRb and other molecules in the p16-CDK4/6-pRb pathway by Western, RT-PCR and CGH in these GBM lines and the data will be presented. We are now testing whether shRNA knockdown and/or re-expression of p15/p16 in the relevant cell lines alters their responsiveness to PD0332991. In conclusion, CDK4/6 inhibitor PD0332991 inhibits cell proliferation and induces G1 cell cycle arrest in p15/p16- null GBM tumors, but is less effective in p15/p16 expressing tumors. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C191.

Background The optimal timing for surgery in patients with mitral regurgitation is disputed. Because of the frequency of left ventricular dysfunction, which is difficult to predict, early surgery has been recommended, but its potential benefits have not been demonstrated. Methods and Results The outcomes of 221 patients (mean age, 65±13 years; 71% males) with flail leaflets diagnosed with two-dimensional echocardiography between 1980 and 1989 who were eligible for operation were analyzed. Group I comprised 63 patients who had early mitral valve surgery (within 1 month after diagnosis). Group II comprised 158 patients initially treated conservatively (80 of whom were operated on later). Group I patients were younger ( P =.009), had more symptoms ( P <.0001), and were more frequently in atrial fibrillation ( P =.023) than group II patients. There was no difference in ejection fraction between the groups. The early surgery strategy was followed by an improved overall survival rate ( P= .028) and a lower incidence of cardiovascular deaths ( P =.025), congestive heart failure ( P =.046), and new chronic atrial fibrillation ( P =.032), as confirmed by multivariate analysis (adjusted risk ratios of 0.31, 0.18, 0.38, and 0.05, respectively; all P< .02). Conclusions In patients with mitral regurgitation due to flail leaflets, the strategy of early surgery versus conservative management is associated with an improved long-term survival rate, decreased cardiac mortality, and decreased morbidity after diagnosis. This outcome advantage suggests that early surgery is a reasonable treatment option to be considered in low-risk candidates with repairable valves and severe mitral regurgitation.

Background Thrombin plays an important role in the pathogenesis of acute coronary thrombosis. We studied the effects of a direct thrombin inhibitor, recombinant desulfatohirudin, and heparin on plasma levels (at 0, 4, 12, and 24 hours) of fibrinopeptide A (FPA), which reflects thrombin action, and prothrombin fragment F1.2, which reflects thrombin generation, in patients with unstable angina. Methods and Results Patients were randomized to one of two doses of heparin (n=50) (target activated partial thromboplastin time, 65 to 90 seconds or 90 to 110 seconds) or one of four doses of r-hirudin (n=113) (0.05, 0.10, 0.20, or 0.30 mg·kg −1 ·h −1 by infusion). r-Hirudin induced a dose-dependent decline in plasma FPA. At 24 hours, FPA levels with 0.1- to 0.3-mg·kg −1 ·h −1 r-hirudin regimens were significantly lower than with 0.05 mg·kg −1 ·h −1 r-hirudin; levels with 0.1- to 0.2-mg·kg −1 ·h −1 r-hirudin regimens were lower than with both heparin regimens. Plasma F1.2 did not decline significantly during therapy with heparin or hirudin except at 0.3 mg·kg −1 ·h −1 hirudin. At 24 hours, they were higher with the 0.05-mg·kg −1 ·h −1 r-hirudin regimen than with other regimens. For comparable levels of thrombin generation (F1.2 levels), FPA levels were higher in heparin patients than in hirudin patients. For the same FPA values, the corresponding F1.2 values were higher in the hirudin group. Conclusions Our findings provide evidence for distinct in vivo effects of the two agents and suggest that r-hirudin is a relatively more potent inhibitor of thrombin action but a less effective inhibitor of thrombin generation than heparin. The lower FPA levels in hirudin patients may reflect its ability to inactivate clot-bound thrombin. The relative clinical efficacies of the two agents need to be defined by clinical trials in progress.

Background —The clinical spectrum of constrictive pericarditis (CP) has been affected by a change in incidence of etiological factors. We sought to determine the impact of these changes on the outcome of pericardiectomy. Methods and Results —The contemporary spectrum of CP in 135 patients (76% male) evaluated at the Mayo Clinic from 1985 to 1995 was compared with that of a historic cohort. Notable trends were an increasing frequency of CP due to cardiac surgery and mediastinal radiation and presentation in older patients (median age, 61 versus 45 years). Perioperative mortality decreased (6% versus 14%, P =0.011), but late survival was inferior to that of an age- and sex-matched US population (57±8% at 10 years). The long-term outcome was predicted independently by 3 variables in stepwise logistic regression analyses: (1) age, (2) NYHA class, and most powerfully, (3) a postradiation cause. Of 90 late survivors in whom functional class could be determined, functional status had improved markedly (2.6±0.7 at baseline versus 1.5±0.8 at latest follow-up [ P <0.0001]), with 83% being free of clinical symptoms. Conclusions —The evolving profile of CP, with increasingly older patients and those with radiation-induced disease in the past decade, significantly affects postoperative prognosis. Long-term results of pericardiectomy are disappointing for some patient groups, especially those with radiation-induced CP. By contrast, surgery alleviates or improves symptoms in the majority of late survivors.

Abstract Purpose: The therapeutic benefit of temozolomide in glioblastoma multiforme (GBM) is limited by resistance. The goal of this study was to elucidate mechanisms of temozolomide resistance in GBM. Experimental Design: We developed an in vivo GBM model of temozolomide resistance and used paired parental and temozolomide-resistant tumors to define the mechanisms underlying the development of resistance and the influence of histone deacetylation (HDAC) inhibition. Results: Analysis of paired parental and resistant lines showed upregulation of O6-methylguanine-DNA methyltransferase (MGMT) expression in 3 of the 5 resistant xenografts. While no significant change was detected in MGMT promoter methylation between parental and derivative-resistant samples, chromatin immunoprecipitation showed an association between MGMT upregulation and elevated acetylation of lysine 9 of histone H3 (H3K9-ac) and decreased dimethylation (H3K9-me2) in GBM12 and GBM14. In contrast, temozolomide resistance development in GBM22 was not linked to MGMT expression, and both parental and resistant lines had low H3K9-ac and high H3K9-me2 within the MGMT promoter. In the GBM12TMZ-resistant line, MGMT reexpression was accompanied by increased recruitment of SP1, C-JUN, NF-κB, and p300 within the MGMT promoter. Interestingly, combined treatment of GBM12 flank xenografts with temozolomide and the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) favored the evolution of temozolomide resistance by MGMT overexpression as compared with treatment with temozolomide alone. Conclusion: This study shows, for the first time, a unique mechanism of temozolomide resistance development driven by chromatin-mediated MGMT upregulation and highlights the potential for epigenetically directed therapies to influence the mechanisms of resistance development in GBM. Clin Cancer Res; 18(15); 4070–9. ©2012 AACR.