Design principles to tailor Hsp104 therapeutics

The hexameric AAA+ disaggregase, Hsp104, collaborates with Hsp70 and Hsp40 via its autoregulatory middle domain (MD) to solubilize aggregated protein conformers. However, how ATP- or ADP-specific MD configurations regulate Hsp104 hexamers remains poorly understood. Here, we define an ATP-specific network of interprotomer contacts between nucleotide-binding domain 1 (NBD1) and MD helix L1, which tunes Hsp70 collaboration. Manipulating this network can: (a) reduce Hsp70 collaboration without enhancing activity; (b) generate Hsp104 hypomorphs that collaborate selectively with class B Hsp40s; (c) produce Hsp70-independent potentiated variants; or (d) create species barriers between Hsp104 and Hsp70. Conversely, ADP-specific intraprotomer contacts between MD helix L2 and NBD1 restrict activity, and their perturbation frequently potentiates Hsp104. Importantly, adjusting the NBD1:MD helix L1 rheostat via rational design enables finely tuned collaboration with Hsp70 to safely potentiate Hsp104, minimize off-target toxicity, and counteract FUS proteinopathy in human cells. Thus, we establish important design principles to tailor Hsp104 therapeutics.

Mechanical force of uterine occupation enables large vesicle extrusion from proteostressed maternal neurons

Large vesicle extrusion from neurons may contribute to spreading pathogenic protein aggregates and promoting inflammatory responses, two mechanisms leading to neurodegenerative disease. Factors that regulate extrusion of large vesicles, such as exophers produced by proteostressed C. elegans touch neurons, are poorly understood. Here we document that mechanical force can significantly potentiate exopher extrusion from proteostressed neurons. Exopher production from the C. elegans ALMR neuron peaks at adult day 2 or 3, coinciding with the C. elegans reproductive peak. Genetic disruption of C. elegans germline, sperm, oocytes, or egg/early embryo production can strongly suppress exopher extrusion from the ALMR neurons during the peak period. Conversely, restoring egg production at the late reproductive phase through mating with males or inducing egg retention via genetic interventions that block egg-laying can strongly increase ALMR exopher production. Overall, genetic interventions that promote ALMR exopher production are associated with expanded uterus lengths and genetic interventions that suppress ALMR exopher production are associated with shorter uterus lengths. In addition to the impact of fertilized eggs, ALMR exopher production can be enhanced by filling the uterus with oocytes, dead eggs, or even fluid, supporting that distention consequences, rather than the presence of fertilized eggs, constitute the exopher-inducing stimulus. We conclude that the mechanical force of uterine occupation potentiates exopher extrusion from proximal proteostressed maternal neurons. Our observations draw attention to the potential importance of mechanical signaling in extracellular vesicle production and in aggregate spreading mechanisms, making a case for enhanced attention to mechanobiology in neurodegenerative disease.

Tuning Hsp104 specificity to selectively detoxify α-synuclein

Hsp104 is an AAA+ protein disaggregase that solubilizes and reactivates proteins trapped in aggregated states. We have engineered potentiated Hsp104 variants to mitigate toxic misfolding of α-synuclein, TDP-43, and FUS implicated in fatal neurodegenerative disorders. Though potent disaggregases, these enhanced Hsp104 variants lack substrate specificity and can have unfavorable off-target effects. Here, to lessen off-target effects, we engineer substrate-specific Hsp104 variants. By altering Hsp104 pore loops that engage substrate, we disambiguate Hsp104 variants that selectively suppress α-synuclein toxicity but not TDP-43 or FUS toxicity. Remarkably, α-synuclein-specific Hsp104 variants emerge that mitigate α-synuclein toxicity via distinct ATPase-dependent mechanisms involving α-synuclein disaggregation or detoxification of soluble α-synuclein conformers. Importantly, both types of α-synuclein-specific Hsp104 variant reduce dopaminergic neurodegeneration in a C. elegans model of Parkinson's disease more effectively than non-specific variants. We suggest that increasing the substrate specificity of enhanced disaggregases could be applied broadly to tailor therapeutics for neurodegenerative disease.

Unique structural features govern the activity of a human mitochondrial AAA+ disaggregase, Skd3

The AAA+ protein, Skd3 (human CLPB), solubilizes proteins in the mitochondrial intermembrane space, which is critical for human health. Skd3 variants with defective protein-disaggregase activity cause severe congenital neutropenia (SCN) and 3-methylglutaconic aciduria type 7 (MGCA7). How Skd3 disaggregates proteins remains poorly understood. Here, we report a high-resolution structure of a Skd3-substrate complex. Skd3 adopts a spiral hexameric arrangement that engages substrate via pore-loop interactions in the nucleotide-binding domain (NBD). Substrate-bound Skd3 hexamers stack head-to-head via unique, adaptable ankyrin-repeat domain (ANK)-mediated interactions to form dodecamers. Deleting the ANK linker region reduces dodecamerization and disaggregase activity. We elucidate apomorphic features of the Skd3 NBD and C-terminal domain that regulate disaggregase activity. We also define how Skd3 subunits collaborate to disaggregate proteins. Importantly, SCN-linked subunits sharply inhibit disaggregase activity, whereas MGCA7-linked subunits do not. These advances illuminate Skd3 structure and mechanism, explain SCN and MGCA7 inheritance patterns, and suggest therapeutic strategies.

Therapeutic genetic variation revealed in diverse Hsp104 homologs

The AAA+ protein disaggregase, Hsp104, increases fitness under stress by reversing stress-induced protein aggregation. Natural Hsp104 variants might exist with enhanced, selective activity against neurodegenerative disease substrates. However, natural Hsp104 variation remains largely unexplored. Here, we screened a cross-kingdom collection of Hsp104 homologs in yeast proteotoxicity models. Prokaryotic ClpG reduced TDP-43, FUS, and α-synuclein toxicity, whereas prokaryotic ClpB and hyperactive variants were ineffective. We uncovered therapeutic genetic variation among eukaryotic Hsp104 homologs that specifically antagonized TDP-43 condensation and toxicity in yeast and TDP-43 aggregation in human cells. We also uncovered distinct eukaryotic Hsp104 homologs that selectively antagonized α-synuclein condensation and toxicity in yeast and dopaminergic neurodegeneration in C. elegans. Surprisingly, this therapeutic variation did not manifest as enhanced disaggregase activity, but rather as increased passive inhibition of aggregation of specific substrates. By exploring natural tuning of this passive Hsp104 activity, we elucidated enhanced, substrate-specific agents that counter proteotoxicity underlying neurodegeneration.

The extent of Ssa1/Ssa2 Hsp70 chaperone involvement in nuclear protein quality control degradation varies with the substrate

Protein misfolding is a recurring phenomenon that cells must manage; otherwise misfolded proteins can aggregate and become toxic should they persist. To counter this burden, cells have evolved protein quality control (PQC) mechanisms that manage misfolded proteins. Two classes of systems that function in PQC are chaperones that aid in protein folding and ubiquitin-protein ligases that ubiquitinate misfolded proteins for proteasomal degradation. How folding and degradative PQC systems interact and coordinate their respective functions is not yet fully understood. Previous studies of PQC degradation pathways in the endoplasmic reticulum and cytosol have led to the prevailing idea that these pathways require the activity of Hsp70 chaperones. Here, we find that involvement of the budding yeast Hsp70 chaperones Ssa1 and Ssa2 in nuclear PQC degradation varies with the substrate. In particular, nuclear PQC degradation mediated by the yeast ubiquitin-protein ligase San1 often involves Ssa1/Ssa2, but San1 substrate recognition and ubiquitination can proceed without these Hsp70 chaperone functions in vivo and in vitro. Our studies provide new insights into the variability of Hsp70 chaperone involvement with a nuclear PQC degradation pathway.

Structure of Calcarisporiella thermophila Hsp104 Disaggregase that Antagonizes Diverse Proteotoxic Misfolding Events

Hsp104 is an AAA+ protein disaggregase with powerful amyloid-remodeling activity. All nonmetazoan eukaryotes express Hsp104 while eubacteria express an Hsp104 ortholog, ClpB. However, most studies have focused on Hsp104 from Saccharomyces cerevisiae and ClpB orthologs from two eubacterial species. Thus, the natural spectrum of Hsp104/ClpB molecular architectures and protein-remodeling activities remains largely unexplored. Here, we report two structures of Hsp104 from the thermophilic fungus Calcarisporiella thermophila (CtHsp104), a 2.70Å crystal structure and 4.0Å cryo-electron microscopy structure. Both structures reveal left-handed, helical assemblies with all domains clearly resolved. We thus provide the highest resolution and most complete view of Hsp104 hexamers to date. We also establish that CtHsp104 antagonizes several toxic protein-misfolding events in vivo where S. cerevisiae Hsp104 is ineffective, including rescue of TDP-43, polyglutamine, and α-synuclein toxicity. We suggest that natural Hsp104 variation is an invaluable, untapped resource for illuminating therapeutic disaggregases for fatal neurodegenerative diseases.

Amyloid assembly and disassembly

Amyloid fibrils are protein homopolymers that adopt diverse cross-β conformations. Some amyloid fibrils are associated with the pathogenesis of devastating neurodegenerative disorders, including Alzheimer's disease and Parkinson's disease. Conversely, functional amyloids play beneficial roles in melanosome biogenesis, long-term memory formation and release of peptide hormones. Here, we showcase advances in our understanding of amyloid assembly and structure, and how distinct amyloid strains formed by the same protein can cause distinct neurodegenerative diseases. We discuss how mutant steric zippers promote deleterious amyloidogenesis and aberrant liquid-to-gel phase transitions. We also highlight effective strategies to combat amyloidogenesis and related toxicity, including: (1) small-molecule drugs (e.g. tafamidis) to inhibit amyloid formation or (2) stimulate amyloid degradation by the proteasome and autophagy, and (3) protein disaggregases that disassemble toxic amyloid and soluble oligomers. We anticipate that these advances will inspire therapeutics for several fatal neurodegenerative diseases.

Summary: This Review showcases important advances in our understanding of amyloid structure, assembly and disassembly, which are inspiring novel therapeutic strategies for amyloid disorders.

Ratchet-like polypeptide translocation mechanism of the AAA+ disaggregase Hsp104

Hsp100 polypeptide translocases are conserved members of the AAA+ family (adenosine triphosphatases associated with diverse cellular activities) that maintain proteostasis by unfolding aberrant and toxic proteins for refolding or proteolytic degradation. The Hsp104 disaggregase from Saccharomyces cerevisiae solubilizes stress-induced amorphous aggregates and amyloids. The structural basis for substrate recognition and translocation is unknown. Using a model substrate (casein), we report cryo-electron microscopy structures at near-atomic resolution of Hsp104 in different translocation states. Substrate interactions are mediated by conserved, pore-loop tyrosines that contact an 80-angstrom-long unfolded polypeptide along the axial channel. Two protomers undergo a ratchet-like conformational change that advances pore loop-substrate interactions by two amino acids. These changes are coupled to activation of specific nucleotide hydrolysis sites and, when transmitted around the hexamer, reveal a processive rotary translocation mechanism and substrate-responsive flexibility during Hsp104-catalyzed disaggregation.

Association of dementia in patients with benign paroxysmal positional vertigo

OBJECTIVE

We conducted a cohort study to investigate whether benign paroxysmal positional vertigo (BPPV) is correlated with an increased risk of dementia.

METHODS

We established a case cohort comprising 7818 patients aged over 20 years who were diagnosed with BPPV from 2000 to 2010. In addition, we formed a control cohort by randomly selecting 31,272 people without BPPV and matched them with the BPPV patients according to gender, age, and index year. Cox proportional hazard regressions were performed to compute the hazard ratio (HR) of dementia after we adjusted for demographic characteristics and comorbidity.

RESULTS

The prevalence of comorbidity was higher among patients with BPPV than among those without BPPV. In addition, patients with BPPV exhibited a 1.24-fold (95% confidence interval, CI 1.09-1.40; P < 0.001) higher risk of dementia than those without BPPV after we adjusted for age, gender, and comorbidity. An analysis stratified according to demographic factors revealed that women with BPPV exhibited a 1.36-fold (95% CI 1.16-1.59; P < 0.001) higher risk of dementia. Patients with BPPV aged over 65 years exhibited a significantly higher risk of dementia (adjusted HR: 1.26; 95% CI 1.10-1.43; P < 0.001) than those without BPPV.

CONCLUSIONS

Patients with BPPV exhibited a higher risk of dementia than those without BPPV.

Mechanistic Insights into Hsp104 Potentiation

Potentiated variants of Hsp104, a protein disaggregase from yeast, can dissolve protein aggregates connected to neurodegenerative diseases such as Parkinson disease and amyotrophic lateral sclerosis. However, the mechanisms underlying Hsp104 potentiation remain incompletely defined. Here, we establish that 2-3 subunits of the Hsp104 hexamer must bear an A503V potentiating mutation to elicit enhanced disaggregase activity in the absence of Hsp70. We also define the ATPase and substrate-binding modalities needed for potentiated Hsp104(A503V) activity in vitro and in vivo. Hsp104(A503V) disaggregase activity is strongly inhibited by the Y257A mutation that disrupts substrate binding to the nucleotide-binding domain 1 (NBD1) pore loop and is abolished by the Y662A mutation that disrupts substrate binding to the NBD2 pore loop. Intriguingly, Hsp104(A503V) disaggregase activity responds to mixtures of ATP and adenosine 5'-(γ-thio)-triphosphate (a slowly hydrolyzable ATP analogue) differently from Hsp104. Indeed, an altered pattern of ATP hydrolysis and altered allosteric signaling between NBD1 and NBD2 are likely critical for potentiation. Hsp104(A503V) variants bearing inactivating Walker A or Walker B mutations in both NBDs are inoperative. Unexpectedly, however, Hsp104(A503V) retains potentiated activity upon introduction of sensor-1 mutations that reduce ATP hydrolysis at NBD1 (T317A) or NBD2 (N728A). Hsp104(T317A/A503V) and Hsp104(A503V/N728A) rescue TDP-43 (TAR DNA-binding protein 43), FUS (fused in sarcoma), and α-synuclein toxicity in yeast. Thus, Hsp104(A503V) displays a more robust activity that is unperturbed by sensor-1 mutations that greatly reduce Hsp104 activity in vivo. Indeed, ATPase activity at NBD1 or NBD2 is sufficient for Hsp104 potentiation. Our findings will empower design of ameliorated therapeutic disaggregases for various neurodegenerative diseases.

A biomarker panel and psychological morbidity differentiates the irritable bowel syndrome from health and provides novel pathophysiological leads

BACKGROUNDS

The development of a reliable biomarker for irritable bowel syndrome (IBS) remains one of the major aims of research in functional gastrointestinal disorders (FGIDs) and is complicated by the absence of a perfect reference standard. Previous efforts based on genetic and immune markers have showed promise, but have not been robust.

AIM

To evaluate an extensive panel of gene expression and serology markers combined with psychological measures in differentiating IBS from health and between subtypes of IBS.

METHODS

Of subjects eligible for analysis (N = 244), 168 met criteria for IBS (60 IBS-C, 57 IBS-D and 51 mixed), while 76 were free of any FGID. A total of 34 markers were selected based on pathways implicated in pathophysiology of IBS or whole human genome screening. Psychological measures were recorded that covered anxiety, depression and somatisation. Models differentiating disease and health were based on unconditional logistic regression and performance assessed through area under the receiver-operator characteristic curve (AUC), sensitivity and specificity.

RESULTS

The performance of a combination of 34 markers was good in differentiating IBS from health (AUC = 0.81) and was improved considerably with the addition of four psychological markers (combined AUC = 0.93). Of the 34 markers considered, discrimination was derived largely from a small subset. Good discrimination was also obtained between IBS subtypes with the best being observed for IBS-C vs. IBS-D (AUC = 0.92); however, psychological variables provided almost no incremental discrimination subtypes over biological markers (combined AUC = 0.94).

CONCLUSIONS

A combination of gene expression and serological markers in combination with psychological measures shows exciting progress towards a diagnostic test for IBS compared with healthy subjects, and to discriminate IBS-C from IBS-D.

Abstract P6-05-06: Association of HER2/neu single nucleotide polymorphism with trastuzumab-related cardiotoxicity

Background: Treatment with trastuzumab prolongs overall survival when given to patients (pts) with Her2/neu+ breast cancer (BC). The primary toxicity of trastuzumab is cardiotoxicity and the incidence is estimated at 2-4% in the adjuvant setting. The mechanism for trastuzumab-induced cardiotoxicity is not known. Although Her2neu expression is usually not seen on cardiac myocytes, its expression has been shown to be upregulated after chemotherapy. Trastuzumab is a monoclonal antibody that binds to the extracellular domain of Her2/neu. We hypothesized that single nucleotide polymorphisms (SNPs) in the Her2/neu receptor may play a role in trastuzumab associated cardiotoxicity.

Methods: 140 pts with BC who were treated with chemotherapy and trastuzumab were enrolled into an IRB approved protocol at the Weill Cornell Medical College between July 2008 and March 2013. Cardiotoxicity was defined as either symptomatic CHF, or a decline in LVEF of 15% (or if LVEF &lt;55% a decline in LVEF of 10%) that required management with medications and led to temporary or permanent discontinuation of trastuzumab. 11 nonsynonomous human ErbB2 SNPs were identified in the National Center for Biotechnology Information SNP database (rs1136201, rs2172826, rs28933368, rs28933369, rs28933370, rs34602395, rs36085723, rs4252633, rs55943169, rs56366519, rs61552325). Genotyping of SNPs was performed on DNA prepared from blood or buccal washes. The relationship between SNP characteristics and cardiotoxicity status was assessed by the chi-square test and multivariable logistic regression analysis.

Results: 140 subjects (29 with cardiotoxicity and 111 without) had 11 SNPs sequenced. Median age of subjects was 56 years (range: 32-85), mean baseline LVEF was 65% (±6%). 16.4% of subjects had hypertension (HTN). 80% of patients were Caucasian, 10% East Asian, 7.1% African American, 2.9% South Asian. There were two SNPs for which there was variation seen among subjects: rs 1136201 (corresponding to codon 655) and rs61552325 (codon 1170). The frequencies of the codon 655 polymorphisms were: AA (Ile/Ile) 67.9%, AG (Ile/Val) 29.3%, and GG (Val/Val) 2.9%. The frequencies of the codon 1170 polymorphisms were: CC (Pro/Pro) 20.7%, GC (Ala/Pro) 45.7%, and GG (Ala/Ala) 33.6%. There was no association observed between the codon 655 polymorphism and cardiotoxicity (p = 0.96). A significant association between cardiotoxicity and the codon 1170 polymorphism was observed, with subjects having cardiotoxicity being more likely to carry the CC allele compared with subjects without cardiotoxicity (34.5% vs 17.1%, p = 0.04). This association persisted after multivariable adjustment for age, race, and HTN status (adjusted OR = 2.60, 95% CI = 1.02-6.62, p = 0.046).

Conclusion: In this study, the Her2/neu 1170 Pro/Pro polymorphism was associated with trastuzumab cardiotoxicity. If confirmed in a larger series, this polymorphism could be used to identify pts who may be at increased risk for cardiotoxicity and who may benefit from treatments associated with less cardiotoxicity. Furthermore, the Her2/neu 1170 SNP has previously been implicated as a minor histocompatibility antigen, and our findings raise the possibility that immune mediated mechanisms may play a role in trastuzumab related cardiotoxicity.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-05-06.

Case-Study Investigation of Equine Maternity via PCR-RFLP: A Biochemistry Laboratory Experiment

A simple and robust biochemistry laboratory experiment is described that uses restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR) products to verify the identity of a potentially valuable horse. During the first laboratory period, students purify DNA from equine samples and amplify two loci of mitochondrial DNA. During the second laboratory period, students digest PCR products with restriction enzymes and analyze the fragment sizes through agarose gel electrophoresis. An optional step of validating DNA extracts through realtime PCR can expand the experiment to three weeks. This experiment, which has an engaging and versatile scenario, provides students with exposure to key principles and techniques of molecular biology, bioinformatics, and evolution in a forensic context.

Tetrathiomolybdate-associated copper depletion decreases circulating endothelial progenitor cells in women with breast cancer at high risk of relapse

BACKGROUND

Bone marrow-derived endothelial progenitor cells (EPCs) are critical for metastatic progression. This study explores the effect of tetrathiomolybdate (TM), an anti-angiogenic copper chelator, on EPCs in patients at high risk for breast cancer recurrence.

PATIENTS AND METHODS

This phase 2 study enrolled breast cancer patients with stage 3 and stage 4 without evidence of disease (NED), and stage 2 if triple-negative. TM 100 mg orally was administered to maintain ceruloplasmin <17 mg/dl for 2 years or until relapse. The primary end point was change in EPCs.

RESULTS

Forty patients (28 stage 2/3, 12 stage 4 NED) were enrolled. Seventy-five percent patients achieved the copper depletion target by 1 month. Ninety-one percent of triple-negative patients copper-depleted compared with 41% luminal subtypes. In copper-depleted patients only, there was a significant reduction in EPCs/ml by 27 (P = 0.04). Six patients relapsed while on study, of which only one patient had EPCs maintained below baseline. The 10-month relapse-free survival was 85.0% (95% CI 74.6%-96.8%). Only grade 3/4 toxicity was hematologic: neutropenia (3.1% of cycles), febrile neutropenia (0.2%), and anemia (0.2%).

CONCLUSIONS

TM is safe and appears to maintain EPCs below baseline in copper-depleted patients. TM may promote tumor dormancy and ultimately prevent relapse.

Abstract P1-15-07: Ixabepilone-associated peripheral neuropathy in metastatic breast cancer patients and its effects on the ultrastructure of neurons

Background: Peripheral neuropathy is a dose-limiting toxicity of most microtubule-stabilizing chemotherapeutic agents. Ixabepilone, a semisynthetic analog of the natural epothilone B, has activity in a wide range of tumors including taxane-resistant disease. In this study, we sought to understand the effect of ixabepilone on the development of peripheral neuropathy both clinically and its effect at the ultrastructural level of the peripheral nerves and circulating factors over time. Parallel studies in animal models of neuropathy were performed at the same time (Proc AACR 2010 Abstract 4184).

Methods: This open-label, non-randomized phase II study enrolled 14 patients with metastatic breast cancer. Ixabepilone was administered by 2 schedules: the FDA approved dose of 40 mg/m2 every 3 weeks (q3w) and 16 mg/m2 on day 1, 8, and 15 of a 28-day cycle (weekly). Five controls, 2 with residual taxane-associated peripheral neuropathy and 3 with no prior chemotherapy or peripheral neuropathy, were also accrued. The primary objectives were to characterize the natural history of ixabepilone-associated peripheral neuropathy using the Total Neuropathy Score Clinical (TNSc) assessment tool prior to each cycle and to correlate changes in the ultrastructure of dermal myelinated nerve fibers via a 3 mm punch biopsy of an area 10 cm above the lateral malleolus every 2 cycles with electron microscopy (EM), as well as circulating factors (both inflammatory and neurotrophic) considered to be important in the pathogenesis of chemotherapy-induced peripheral neuropathy. Secondary objectives included progression-free survival (PFS) and non-neurologic toxicity.

Results: 14 patients were enrolled and were equally divided between the 2 schedules of ixabepilone chemotherapy. There were no differences in baseline characteristics between the two groups. Mean age was 54 years (range 32–71). Mean number of previous chemotherapy regimens was 3.5 (range 0–8). 57% of patients had received a taxane in the adjuvant setting and 64% in the metastatic setting. The mean neuropathy score (TNSc) at baseline was 4.6 (range 1–11). At a mean cumulative dose of 185 mg/m2, the TNSc with ixabepilone q3w schedule was 3.7 points higher/worse (95% CI: 2.2–5.3, p = 0.03) than the mean score observed in patients on the weekly schedule. The sensory component was most significantly affected, predominantly numbness. In 3 patients, the chemotherapy schedule was changed from every 3 weeks to weekly due to &gt; grade 2 toxicity at a mean cumulative dose of 107 mg/m2, and TNSc decreased/improved by 2.7 points. PFS in patients on q3w ixabepilone was 133 days (range 28–280) and in patients on weekly ixabepilone was 179 days (range 66–336), nonsignificant. Evaluation of EM and circulating factors is ongoing.

Conclusions: Weekly ixabepilone appears to have a more favorable neurotoxicity profile compared to the standard q3w schedule. Integration of the EM data and the circulating factor data are underway and will be presented. Ixabepilone-associated peripheral neuropathy may improve in patients switched to weekly ixabepilone without compromising efficacy.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-15-07.

Abstract P6-11-04: Targeting the tumor microenvironment: tetrathiomolybdate decreases circulating endothelial progenitor cells in women with breast cancer at high risk of relapse

Background: Bone marrow-derived endothelial progenitor cells (EPCs) constitute an important part of the tumor microenvironment and are critical for metastatic progression in preclinical models and breast cancer patients (Jain et al, Breast Cancer Res Treat, 2012). Tetrathiomolybdate (TM), a copper-depleting compound inhibits angiogenesis, tumor growth, and metastasis. This study explores the effect of TM on EPCs in patients at high risk for breast cancer recurrence.

Methods: This phase II study enrolled stage 3, 4 without evidence of disease (NED), and any node-positive triple negative breast cancer patient. Only concomitant hormone therapy was allowed. Patients received induction TM 180 mg daily at baseline followed by an equal or lower daily dose (median 100 mg, range 0–140) to maintain ceruloplasmin (Cp) level &lt; 17 mg/dl (target for copper depletion). We monitored EPCs (CD45dim/CD133+/VEGFR2+), Cp, CEA, and CA15-3 at baseline and monthly. Wilcoxon signed-rank was used to compare Cp and EPC levels between baseline and subsequent time points. All p-values were two-sided with statistical significance evaluated at the 0.05 alpha level.

Results: 50 patients (33 adjuvant, 17 Stage 4 NED, and 22 triple negative) were enrolled. In the first 40 patients enrolled who had received at least 24 months of TM, EPC and Cp data were available for analysis. Of these 40 patients, 1 patient did not take TM due to patient preference, and 736 cycles of TM (average 18.9 per patient) were administered. Median age was 50 years (range 29–66). Median number of tumor size and positive lymph nodes among adjuvant patients were 3.5 cm (range 1.2–7) and 9 (range 0–42), respectively. Of the patients receiving hormone therapy, 11 patients were on tamoxifen and 16 patients were on an aromatase inhibitor. Median baseline Cp level was 30 mg/dL (range 20–47). 71% patients adequately copper depleted at month 1 to a mean Cp of 14.8 mg/dL. A larger proportion of triple negative patients copper depleted (82%) compared to hormone receptor positive subtypes (47%) and HER2/neu positive subtypes (67%). Median EPCs/ml decreased from baseline to last dose by 16 in patients that achieved the copper depletion target, p = 0.014. Conversely, in patients that did not copper deplete, median EPCs/ml increased by 136, p = 0.005. Of the 50 patients on study, 7 patients relapsed in which a significant increase in EPCs preceded an objective clinical relapse and a tumor marker rise by a median of 1 month. Only grade 3/4 toxicity was hematologic, occurred in 49 cycles (6.7%), and resolved in 5–13 days with TM held and resumed at a lower dose.

Conclusions: TM is a well-tolerated oral copper chelator that may contribute to maintaining EPCs below baseline in copper-depleted patients. Molecular subtype may impact on the ability to copper deplete. EPCs may have potential as a surrogate marker for early relapse and as a therapeutic target for interrupting the metastatic progression.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-11-04.

Employment after a breast cancer diagnosis: a qualitative study of ethnically diverse urban women

Employment status is related to treatment recovery and quality of life in breast cancer survivors, yet little is known about return to work in immigrant and minority survivors. We conducted an exploratory qualitative study using ethnically cohesive focus groups of urban breast cancer survivors who were African-American, African-Caribbean, Chinese, Filipina, Latina, or non-Latina white. We audio- and video-recorded, transcribed, and thematically coded the focus group discussions and we analyzed the coded transcripts within and across ethnic groups. Seven major themes emerged related to the participants' work experiences after diagnosis: normalcy, acceptance, identity, appearance, privacy, lack of flexibility at work, and employer support. Maintaining a sense of normalcy was cited as a benefit of working by survivors in each group. Acceptance of the cancer diagnosis was most common in the Chinese group and in participants who had a family history of breast cancer; those who described this attitude were likely to continue working throughout the treatment period. Appearance was important among all but the Chinese group and was related to privacy, which many thought was necessary to derive the benefit of normalcy at work. Employer support included schedule flexibility, medical confidentiality, and help maintaining a normal work environment, which was particularly important to our study sample. Overall, we found few differences between the different ethnic groups in our study. These results have important implications for the provision of support services to and clinical management of employed women with breast cancer, as well as for further large-scale research in disparities and employment outcomes.

Randomised clinical trial: alosetron improves quality of life and reduces restriction of daily activities in women with severe diarrhoea-predominant IBS

BACKGROUND

Patients with irritable bowel syndrome with diarrhoea (IBS-D) experience restriction in daily activities and decreased health-related quality of life (QOL).

AIM

To investigate effects of alosetron on patient-reported health-related QOL, satisfaction and productivity in women with severe IBS-D.

METHODS

A total of 705 women (severe IBS-D, Rome II criteria) randomised to alosetron 0.5 mg QD, 1 mg QD, 1 mg BID, or placebo for 12 weeks were studied. IBSQOL, treatment satisfaction, daily activities, and lost workplace productivity (LWP) were evaluated at randomisation and Week 12.

RESULTS

One or more doses of alosetron significantly improved all IBSQOL domains except for sexual function from baseline vs. placebo. The magnitude of IBSQOL changes was consistent with a clinically meaningful effect. Alosetron 0.5 mg QD and 1 mg BID significantly reduced IBS interference with social/leisure activities and LWP from baseline vs. placebo [social/leisure (mean ±S.E.) days lost: -6.7 ± 0.8, -7.0 ± 0.9, P < 0.01; LWP (mean ± S.E.) h lost: -11.0 ± 3.3, -21.1 ± 4.1, P < 0.05 respectively]. Significantly more patients treated with alosetron reported satisfaction vs. placebo. Improvements in IBSQOL, LWP, and treatment satisfaction significantly correlated with global improvement of IBS symptoms. The incidence of adverse events with alosetron was low with constipation being the most commonly reported event. A single case of ischaemic colitis occurred, in a patient receiving alosetron 0.5 mg QD.

CONCLUSIONS

In women with severe IBS-D, alosetron treatment, including 0.5 mg QD, resulted in statistically significant and clinically relevant improvements in health-related QOL, restriction of daily activities and treatment satisfaction over placebo. IBS symptom improvement corresponded with positive changes in IBSQOL, LWP and treatment satisfaction.

Abstract P3-15-06: No Correlation between Endocrine Symptoms and Musculoskeletal Symptoms in Women Receiving Adjuvant Aromatase Inhibitor Therapy

Background:

The etiology of Aromatase Inhibitor (AI) associated musculoskeletal symptoms remains unclear. It has been proposed that musculoskeletal side effects are related to the estrogen depletion achieved on AI therapy. Estrogen depletion with AI therapy is known to result in endocrine side effects. The 18-item Functional Assessment of Cancer Therapy Breast Cancer-Endocrine Subscale (FACTB-ES) is a reliable and well validated quality of life questionnaire shown to be sensitive to changes in endocrine symptoms in breast cancer patients. The objective of this study was to determine whether among women with breast cancer treated with adjuvant AI therapy, self reported musculoskeletal side effects correlate with increased hormonal side effects as measured by the FACTB-ES. Methods:

In this 6 month, single center, prospective cohort study, post-menopausal women with hormone-sensitive, non-metastatic breast cancer prescribed AIs by their treating oncologist were evaluated by a rheumatologist at baseline (before starting the AI) and at 6 months. Women who reported new or worsening musculoskeletal symptoms since starting the AI were classified as symptomatic. The FACTB-ES was administered at each visit.

Changes in scores between baseline and 6 months were compared between

the symptomatic and asymptomatic groups

Results:

Thirty-five subjects completed the 6 month follow up period. Nineteen (54%) were symptomatic and n=2 (5.7%) discontinued the AI due to these musculoskeletal symptoms. Mean time to onset of symptoms was 6 weeks (range 2 to 18 weeks). Baseline characteristics including age, ethnicity and body mass index did not differ between the groups. There was no significant difference in hormonal symptoms between groups. Both groups had equivalent worsening of their endocrine symptoms as seen by the reduction in their FACTB-score. The mean change in FACTB-ES score was -2.52 (range: -31.00, 23.00) in the symptomatic women versus -2.06 (range: -19.00, 22.21) in the asymptomatic women (Wilcoxon rank sum p=0.95). Conclusions:

These data suggest that endocrine symptoms as measured by the FACTB-ES do not correlate with the development of musculoskeletal pain in women treated with adjuvant AI therapy for breast cancer. Though larger studies are necessary to confirm these results, the musculoskeletal symptoms associated with AI use may not be estrogen-dependent.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-15-06.

Abstract P2-16-14: The Effect of Tetrathiomolybdate (TM) on Circulating Endothelial Progenitor Cells in Women at Moderate to High Risk of BC Recurrence

Background: Bone marrow (BM) derived endothelial progenitor cells (EPCs) are critical to tumor angiogenesis, are increased in BC patients (pts) and are probably an early marker for paclitaxel response. Copper is required for angiogenesis, and pre-clinical data suggest that TM, a copperdepleting compound, inhibits angiogenesis and maintains tumor dormancy through unknown mechanisms. We sought to measure the effect of TM on BM derived EPCs in pts at high risk of BC recurrence and to evaluate the effect of copper depletion on their absolute number. Methods: This analysis is part of an ongoing phase II study of TM in BC pts at high risk of recurrence defined as any node positive triple negative (TN) BC, Stage III or IV with no evidence of disease (NED). All therapy other than hormonal was completed at least 6 weeks prior to study. Treatment: TM 180 mg daily to achieve a target ceruloplasmin (Cp) level of 5-15 mg/dL (copper depletion), and then 100 mg daily. We monitored levels of EPCs (CD45dim, CD133+, VEGFR2+), CEA, CA15-3, and Cp at baseline and monthly. Imaging studies are done every 6 months (mos). Initial study duration is 24 mos. Extension study for an additional 24 mos in selected pts. Results: 40 pts are enrolled and 566 cycles of TM have been administered. Adjuvant: 28 pts, Stage 4 NED: 12 pts, Triple negative: 11 pts (4 stage 4 NED, 7 Adjuvant). Median age is 51 yrs (range: 29-64). Median number of positive lymph nodes among Stage 2/3 pts is 7 (4-42). Median baseline Cp level is 29 mg/dL (21-47). Among 36 pts who have reached target Cp, the median time to target is 4 wks (2-20 wks). Four pts discontinued treatment before reaching target. The median baseline EPCs is 0.01 cells/ml (0.0-0.286), and the majority of pts’ EPCs were maintained below baseline when Cp levels remained below target (i.e. copper depleted). Toxicity: Grade 3/4 neutropenia occurred in 15 cycles (2.6%) with 1 pt with febrile neutropenia. One cycle was complicated by Grade 3 anemia. All resolved 5-13 days later with TM held and resumed at a lower dose. No other grade 3/4 toxicity was observed. Six pts were diagnosed with recurrent breast cancer at 1, 2, 2, 9, 10 and 10 mos. An EPC rise preceded an abnormal marker or overt relapse by 3-5 months in 4 of 6 pts (2 pts too early to tell). Conclusions: TM is well tolerated in breast cancer patients. TM might contribute to maintaining EPCs below baseline in pts who are copper depleted. We postulate that the increased EPCs noted in 4 pts with recurrent disease 2-4 months prior to overt relapse could represent the turning on of an angiogenic switch, resulting in an outpouring of BM derived EPCs to the new site of metastasis. Other studies geared toward understanding the mechanism for metastases are underway. The trial continues to accrue.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-16-14.

Phase I trial of ixabepilone plus pegylated liposomal doxorubicin in patients with adenocarcinoma of breast or ovary

BACKGROUND

Ixabepilone is a semisynthetic epothilone B analogue that is active in taxane-resistant cell lines and has shown activity in patients with refractory breast and ovarian cancer. We carried out a phase I trial of ixabepilone plus pegylated liposomal doxorubicin (PLD) in patients with advanced taxane-pretreated ovarian and breast cancer.

METHODS

Patients with recurrent ovarian or breast carcinoma received PLD every 3 or 4 weeks plus five different dose schemas of ixabepilone in cohorts of three to six patients.

RESULTS

Thirty patients received a total of 142 treatment cycles of the PLD-ixabepilone combination. The recommended phase II dose and schedule of ixabepilone was 16 mg/m(2) on days 1, 8, and 15 plus PLD 30 mg/m(2) given on day 1, repeated every 4 weeks. Hand-foot syndrome and mucositis were dose limiting when both ixabepilone and PLD were given every 3 or 4 weeks. Objective responses were observed in 3 of 13 patients (23%) with breast cancer and 5 of 17 patients (29%) with ovarian cancer.

CONCLUSION

Ixabepilone may be safely combined with PLD, but tolerability is highly dependent upon the scheduling of both agents. This combination demonstrated efficacy in patients with breast and ovarian cancer and merits further evaluation in these settings.

An exploratory study of sunitinib plus paclitaxel as first-line treatment for patients with advanced breast cancer

Background: Sunitinib has shown single-agent activity in patients with previously treated metastatic breast cancer (MBC). We investigated the safety of the combination of sunitinib and paclitaxel in an exploratory study of patients with locally advanced or MBC.

Methods: Patients received oral sunitinib 25 mg/day (with escalation to 37.5 mg/day as tolerated) on a continuous daily dosing schedule and paclitaxel 90 mg/m² on days 1, 8, and 15 of each 28-day cycle. Study endpoints included safety (primary endpoint), pharmacokinetics, and antitumor activity.

Results: Twenty-two patients were enrolled. The most frequent adverse events (AEs) were fatigue/asthenia (77%), dysgeusia (68%), and diarrhea (64%). Grade 3 AEs included neutropenia (43%), fatigue/asthenia (27%), neuropathy (18%), and diarrhea (14%). No drug–drug interaction was observed on the basis of pharmacokinetic analysis. Of 18 patients with measurable disease at baseline, 7 (38.9%) achieved objective responses (including 2 complete and 5 partial responses). Clinical responses were observed in three of nine patients with triple-negative receptor status (estrogen receptor negative, progesterone receptor negative, and human epidermal growth factor receptor-2 negative).

Conclusions: These data indicate that sunitinib and paclitaxel in combination are well tolerated in patients with locally advanced or MBC. No drug–drug interaction was detected and there was preliminary evidence of antitumor activity.

A Phase II Trial Tetrathiomolybdate (TM), a Copper Depleting Compound, and Its Effect on Circulating Endothelial Progenitor Cells (EPCs) in Patients with Breast Cancer (BC) at High Risk of Recurrence

Background: EPCs are critical to tumor angiogenesis, are increased in BC patients (pts) and are probably an early marker for paclitaxel response. Copper is required for angiogenesis, and pre-clinical data suggest that TM, a copper-depleting compound, inhibits angiogenesis and maintains tumor dormancy. We sought to measure the effect of TM on circulating endothelial progenitor cells (EPCs) in pts at high risk of BC recurrence and to evaluate the effect of copper depletion on EPCs. Methods: This analysis is part of an ongoing phase II study of TM in BC pts at high risk of recurrence defined as any node positive triple negative (TN) BC, Stage III or IV with no evidence of disease (NED). All therapy other than hormonal was completed at least 6 weeks prior to study. Treatment: TM 180 mg daily to achieve a target ceruloplasmin (Cp) level of 5-15 mg/dL (copper depletion), and then 100 mg daily. We monitored levels of EPCs (CD45dim, CD133+, VEGFR2+), CEA, CA15-3, and Cp at baseline and monthly. Imaging studies are done every 6 months (mos). Results: 28 pts are enrolled and 304 cycles of TM have been administered. Adjuvant: 20 pts, Stage 4 NED: 8 pts, Triple negative: 8 pts (5 stage IV NED, 3 Adjuvant) The median age is 51 years (range: 29-64), median number of positive lymph nodes among Stage III patients is 7 (4-42). The median baseline Cp level was 28 mg/dL (21-43). Among 21 patients who have reached target Cp, the median time to target is 6 weeks (2-16 weeks). Two pts discontinued treatment before reaching target. The median baseline EPCs is 17.38 cells/ml (0.0-286.1) Although there was a trend toward increased EPCs at month 1, this was not statistically significant (p=0.8964) and the majority of pts EPCs were maintained below baseline over time when Cp levels were below target (ie. copper depleted). Toxicity: Grade 3/4 neutropenia occurred in 3 patients (0.02%) with 1 pt with febrile neutropenia. All resolved 5-13 days later with TM held and resumed at a lower dose in 2 patients. No other grade 3/4 toxicity was observed. Three patients were diagnosed with recurrent breast cancer at 1, 9 and 10 mos. An EPC rise preceded an abnormal marker or overt relapse by 3-5 months in 2 of 3 pts. Conclusions: TM is well tolerated in breast cancer patients. TM might contribute to maintaining EPCs below baseline in pts who are copper depleted. We postulate that the increased EPCs noted in both patients with recurrent disease 2-4 months prior to overt relapse could represent the turning on of an angiogenic switch, resulting in an outpouring of CEPCs to the new site of metastasis. Other studies geared toward understanding the mechanism for metastases are underway. The trial continues to accrue.Supported by the Susan B Komen for the Cure, NY Community Trust, Breast Cancer Alliance of Greenwich and the Madeline and Stephen Anbinder Foundation.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6090.

Differences in Breast Cancer Subtypes among Asian-American Women with Invasive Breast Cancer in New York City

Background: Specific breast cancer (BC) subtypes conferring distinct phenotypic and prognostic outcomes have been defined by molecular gene expression arrays. A recent study suggested that differences in BC subtypes exist among ethnic subgroups of Asian women in California. It has also been reported that there are differences in clinical outcomes among Asians with BC in the US, with Filipinos having a worse prognosis compared with other Asians. We sought to determine whether differences in BC subtypes exist among Asians in New York.Methods: Using outpatient registration records from Weill Cornell Breast Center and St. Vincent's Medical Center in New York City, we identified patients who were diagnosed with stage I, II, or III invasive BC between 1997 and 2007 who were of Chinese, Filipino, Japanese or Korean ethnicity. We reviewed pathology records according to an IRB approved protocol and recorded patient data for age, stage, grade, estrogen receptor (ER), progesterone receptor (PR) status, and HER-2/neu at diagnosis. Immunohistochemical surrogates for the four molecularly defined breast cancer subtypes were used according to accepted definitions (Luminal A: ER+Her2-; Luminal B: ER+ Her2+; Her2/neu: Her2+ ER-; Basal-like: ER-PR-, Her2-) Using chi-square analysis, we explored the relationship between ethnicity and BC subtypes.Results: 346 Asian women were identified with invasive breast cancer. Among the Chinese subgroup, 67% were of the Luminal A subtype, 15.3% were Luminal B, 10% were the Her2/neu subtype and 8.5% were Basal-like. Filipinos had a higher proportion of Luminal B cancers compared to the other ethnic groups. Filipinos and Koreans had a higher proportion of the Her2+/ER- subtype compared to Chinese and Japanese (P=0.004 by chi-square test). When considering all Her2/neu positive cancers, Filipinos had a significantly higher proportion of HER-2/neu positivity (46%) compared to Chinese (25%), Japanese (14%) and Korean (29%) groups (P=0.002). Filipinos and Koreans had a higher proportion of ER negative cancers and Grade III cancers compared to Chinese and Japanese (P=0.001 for ER status and P=0.01 for grade). In our series, Korean subjects were significantly younger than the other three ethnic groups (P&lt;0.0001 by AVOVA test).Conclusions: Differences in BC subtypes exist among Asian women with invasive breast cancer in New York. Filipino women are significantly more likely to have HER-2/neu positive BC compared with Chinese, Japanese, and Korean women. Our results are supportive of results from a study in which differences in distribution of Her2/neu positive cancers among Asians in California were seen. Furthermore, these findings provide one explanation for the worse clinical outcome for Filipinos compared with other Asians that has been previously reported.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3067.

The effect of tetrathiomolybdate on circulating endothelial progenitor cells in patients with breast cancer at high risk of recurrence

Abstract #1036

Background: Endothelial progenitor cells are critical to tumor angiogenesis and are increased in breast cancer patients. Copper is required for angiogenesis, and pre-clinical data suggest that tetrathiomolybdate (TM), a copper-depleting compound, inhibits angiogenesis and maintains tumor dormancy. We sought to measure circulating endothelial progenitor cells (CEPCs) in patients at high risk of breast cancer recurrence and to evaluate the effect of copper depletion on CEPCs.&#x2028; Methods: This analysis is part of an ongoing phase II study of TM in breast cancer patients at high risk of recurrence defined as Stage III or IV with no evidence of disease. All therapy other than hormonal was completed at least 6 weeks prior to study. Treatment: TM 180 mg daily to achieve a target ceruloplasmin (Cp) level of 5-15 mg/dL (copper depletion), and then 100 mg daily. We monitored levels of CEPCs (CD45dim, CD133+, VEGFR2+), CEA, CA15-3, and Cp at baseline and monthly. CEPCs were also measured in 6 healthy controls.&#x2028; Results: To date we have enrolled 16 patients with a median age of 51 years (range: 29-64). 14 had a history of Stage III disease, while 2 were considered to be Stage IV with no evidence of disease. The median number of positive lymph nodes among Stage III patients was 7 (1-42), with 2 patients having received neoadjuvant therapy. The median baseline Cp level was 28 mg/dL (21-41). Among 12 patients who have reached target Cp, the median time to target was 1 month (1-3 months). The median follow-up of the 4 patients who have not yet achieved target is 2.5 months. 1 of these discontinued treatment before reaching target. The median baseline CEPCs was lower in patients than healthy controls: 0.022 cells/μL (0.000-0.286) vs. 0.123 cells/μL (0.058-0.418); p=0.03. There was no statistically significant change in CEPCs from baseline over time.&#x2028; One patient was diagnosed with recurrent breast cancer at month 10. A rise in her CEPCs preceded a rise in a CEA and overt relapse by 1 and 5 months, respectively.&#x2028; Toxicity: Grade 3/4 neutropenia occurred in 3 patients. TM was held, and this resolved 5-13 days later, after which TM was resumed. No other grade 3/4 toxicity was observed. One patient discontinued TM due to diarrhea attributed to the lactose used in the compounding of TM.&#x2028; Conclusions: TM is well tolerated in breast cancer patients. We postulate that the increased CEPCs noted in one patient at month 4, 6 months prior to overt relapse, could represent the “turning on” of an angiogenic switch, resulting in an outpouring of CEPCs to the new site of metastasis. The trial is ongoing, and with additional follow-up other trends might emerge.&#x2028; Supported by Komen for the Cure Foundation, Anbinder Foundation, NY Community Trust and Breast Cancer Alliance of Greenwich.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1036.

Phase I clinical trial of ixabepilone and pegylated liposomal doxorubicin in patients with advanced breast or ovarian cancers: New York Cancer Consortium Trial P7229

2570

Background: Ixabepilone (IX) is a semisynthetic epothilone B analog with activity in patients (pts) with taxane refractory cancer. Two phase III clinical trials in breast cancer (BC) and a phase II study in ovarian cancer (OC) have recently been completed. Pegylated liposomal doxorubicin (PLD) is used for the treatment of platinum refractory OC and has activity in patients with metastatic BC. Methods: We have completed enrollment of a phase I study of PLD IV and ixabepilone IV over 3 hours. 18 pts with metastatic cancer (10 BC and 8 OC) with median age 51 were enrolled from 1/13/06 to 12/22/06. A total of 60 cycles has been administered to date. 3 OC patients enrolled at dose level 3 have not yet completed 2 cycles of treatment and are not yet evaluable. Results: Dose limiting toxicities (DLT) based on toxicities experienced during the first 2 cycles is provided in the table below. Adverse events (AE) occurring in any cycle were: Grade 4 AE: neutropenia < 7 days (1 pt). Grade 3 AE: palmar plantar erythrodysesthesia (PPE) (4), mucositis (3), infection (2), fatigue (2), neutropenia (2), thrombocytopenia (2), anemia (1), neuropathy (1), bilirubin (1). Non-hematological grade 2 AEs included: mucositis (4), PPE (3), infection (2), neuropathy (2), rash (3), pain (3), fever (1), myalgias (1), and anorexia (1). Responses so far for 10 BC pts are PR (1) SD (3) PD (6) and for 5 OC pts are PR (1) SD (2) PD (2). Updated results will be presented. Conclusions: Although the recommended phase II dose when given every 3 weeks is 30 mg/m2 for PLD and 32 mg/m2 for IX by our criteria, PPE and mucositis became problematic when treatment was continued beyond 2 cycles. We are therefore exploring a 4 week PLD schedule, evaluating IX given either every 4 weeks (as shown) or weekly (on days 1, 8, and 15). A phase II trial of the combination in platinum refractory OC will be initiated upon completion of the phase I. Supported by N01-CM-62204

[Table: see text]

[Table: see text]

Circulating endothelial progenitor cells correlate to stage in patients with invasive breast cancer

616

Background: Tumor growth and metastasis is dependent on neo-angiogenesis. Both pre-existing and circulating vascular cells have been shown to contribute to the assembly of tumor neo-vessels in specific tumors. Mobilization of endothelial progenitor cells (EPCs) from the bone marrow constitutes a crucial step in the formation of de novo blood vessels, and levels of peripheral blood EPCs have been shown to be increased in certain malignant states. However, the role of circulating EPCs in breast cancer is largely unknown. Methods: We recruited twenty-five patients with biopsy-proven invasive breast cancer (BC) at Weill Cornell Breast Center to participate in a pilot study investigating the correlation of circulating EPCs to extent of disease and initiation of chemotherapy. For each patient, a baseline sample was drawn before systemic treatment, and for seventeen of those patients, a second sample was taken after the first round of chemotherapy. Levels of peripheral blood EPCs, as defined by co-expression of CD133 and VEGFR2, were quantified by flow cytometry. Results: BC patients with stage III & IV disease had statistically higher levels of circulating EPCs than did patients with stage I & II disease (median=165,000 EPCs/5×106MNCs vs. median=6,920 EPCs/5x106MNCs, respectively, p < 0.0001 by Wilcoxon rank-sum test). In addition, in late-stage patients, levels of EPCs demonstrated a statistically significant drop after initiation of chemotherapy (median=162,500 EPCs/5x106MNCs [pre] vs. median=117,500 EPCs/5x106MNCs [post], p = 0.01 by Wilcoxon signed-rank test). Conclusion: These results suggest that circulating EPCs may serve as a potential tumor biomarker in breast cancer and that EPCs may represent a plausible target for future therapeutic intervention. Supported in part by the Mentored Medical Student in Clinical Research Program (General Clinical Research Center/National Institutes of Health Grant M01RR00047), Madeline & Stephen Anbinder Clinical Scholar Award, and Anne Moore Breast Cancer Research Fund

No significant financial relationships to disclose.

Bioavailability and therapeutic activity of alicaforsen (ISIS 2302) administered as a rectal retention enema to subjects with active ulcerative colitis

BACKGROUND

Alicaforsen is a phosphorothioate-modified antisense oligodeoxynucleotide designed to sequence-specifically reduce intercellular adhesion molecule 1 messenger RNA levels.

AIMS

To determine the systemic and local bioavailability of alicaforsen, and its activity when administered as a once daily enema in subjects with active ulcerative colitis. METHODS An open-label study was conducted to assess the relative absorption (local and systemic pharmacokinetics) and pharmacologic activity of alicaforsen enema in subjects with active ulcerative colitis. Fifteen subjects received nightly enemas of alicaforsen (240 mg) for a treatment period of 6 weeks. Alicaforsen concentrations in plasma and colonic tissue biopsies were determined. Disease activity index and multiple measurements including endoscopy were used to assess alicaforsen activity in these subjects.

RESULTS

Plasma concentrations of parent alicaforsen represented < 0.6% mean bioavailability when compared with historical intravenous area under the plasma concentration-time curves. Concentrations of the intact oligonucleotide in mucosal colonic tissue biopsies were orders of magnitude higher than those observed in plasma. A 46% reduction in mean Disease Activity Index and 33% rate of remission as defined by complete mucosal healing were observed at the end of treatment. Conclusion These data confirm that alicaforsen enema provides local treatment for a local disease with little meaningful systemic exposure.

A phase II dose ranging, double-blind, placebo-controlled study of alicaforsen enema in subjects with acute exacerbation of mild to moderate left-sided ulcerative colitis

BACKGROUND

Alicaforsen is an antisense oligonucleotide designed to inhibit expression of human intercellular adhesion molecule 1. Previous clinical studies have demonstrated activity of alicaforsen enema in ulcerative colitis and pouchitis.

AIM

To determine the minimally effective dosing regimen of alicaforsen enema in subjects with mild to moderate left-sided ulcerative colitis.

METHODS

Randomized, placebo-controlled, double-blind, two-dose ranging multicentre study. One hundred and twelve subjects were equally randomized to receive one of four alicaforsen enema regimens or placebo daily for 6 weeks. Primary end point was Disease Activity Index at week 6. Secondary end points included evaluation of clinical improvement, relapse rates and durability of response. Analysis of data were performed on the intent-to-treat population.

RESULTS

No significant difference was observed between treatment arms and placebo in the primary end point. A prolonged reduction in mean% Disease Activity Index relative to baseline was observed in the daily 240 mg alicaforsen enema treatment arm in comparison with placebo from week 18 (51% vs. 18%, P=0.04) to week 30 (50% vs. 11%, P=0.03).

CONCLUSIONS

Alicaforsen enema was safe and well tolerated at all doses studied. The durability of the response to alicaforsen enema treatment may suggests a disease-modifying effect.

Phase III study of cyclophosphamide, doxorubicin, and fluorouracil (CAF) plus leucovorin versus CAF for metastatic breast cancer: Cancer and Leukemia Group B 9140

PURPOSE

To determine whether biochemical modulation with LV (leucovorin) enhances the efficacy of CAF (cyclophosphamide, doxorubicin, and fluorouracil) against metastatic breast cancer.

PATIENTS AND METHODS

Women with histologically confirmed stage IV breast cancer, Cancer and Leukemia Group B (CALGB) performance status 0 to 2, and no prior chemotherapy for metastatic disease were randomly assigned to receive CAF (cyclophosphamide 500 mg/m2 day 1, doxorubicin 40 mg/m2 day 1, and fluorouracil [FU] 200 mg/m2 intravenous bolus days 1 to 5) with or without LV (LV 200 mg/m2 over 30 minutes days 1 to 5 given 1 hour before FU).

RESULTS

Two hundred forty-two patients were randomly assigned to treatment; 124 patients had visceral crisis and 40 patients had a CALGB performance status score of 2. The median follow-up was 6 years. The two study arms were similar with regard to serious adverse events; four patients died from treatment-related causes, two patients on each study arm. Predictive variables for time to treatment failure and survival were visceral disease and performance status. The overall response rate was 29% for CAF versus 28% for CAF plus LV. The median time to treatment failure (9 months) and median survival (1.7 years) did not differ by treatment arm.

CONCLUSION

Modulation of CAF with LV improved neither response rates nor survival among women with metastatic breast cancer, compared with CAF alone. Multivariate analyses confirmed the prognostic importance of performance status and visceral crisis. However, the overall and complete response rates, response durations, time to treatment failure, and survival were the same in the two treatment arms.

Sedation in pediatric endoscopy

The increase in diagnostic, radiologic, and minor surgical procedures performed on pediatric patients outside of the traditional surgical suite setting has resulted in a marked increase in the use of conscious sedation. Not long ago, pediatric gastroenterologists were reticent about using intravenous sedation for pediatric endoscopy. With increased experience, careful screening, and the specialization of pediatric gastroenterology, however, endoscopy can now be performed safely with intravenous sedation on almost all patients.

The CD28 and CTLA-4 receptors associate with the serine/threonine phosphatase PP2A

CD28 and CTLA-4 are related members of a family of T lymphocyte cell surface receptors that function to regulate T cell activation. We have found that the cytoplasmic domains of both CTLA-4 and CD28 can associate with members of the PP2A family of serine/threonine phosphatases. The association of PP2A with CD28 was negatively regulated by tyrosine phosphorylation of the CD28 cytoplasmic domain. Inhibition of PP2A activity in Jurkat leukemia T cells by treatment with okadaic acid or by expression of a dominant-negative mutant enhanced T cell activation induced by CD28 engagement. Interactions between cell surface receptors such as CTLA-4 and CD28 and serine/threonine phosphatases may represent a novel mechanism for modulating the intracellular signal transduction pathways associated with cell activation.

Structural analysis of CTLA-4 function in vivo

CTLA-4-mediated inhibition of T cell activation may be accomplished by competition for ligands and/or by signals mediated through the intracellular domain. Studies have implicated Tyr201 in the cytoplasmic domain of CTLA-4 in regulating CTLA-4 signal transduction and intracellular trafficking. To investigate the mechanism of CTLA-4 function in vivo, transgenes encoding wild-type CTLA-4 (FL), a mutant lacking the cytoplasmic domain of CTLA-4 (DeltaCTLA-4 tail), or a CTLA-4 Tyr201 mutant (Y201V) were introduced into CTLA-4-deficient mice. CTLA-4-/- mice display an autoimmune lymphoproliferative disorder resulting in tissue destruction and early death. When either the FL or the Y201V transgene was bred into CTLA-4-/- animals, a complete rescue from lymphoproliferation and autoimmunity was observed. In contrast, CTLA-4-/- mice expressing the DeltaCTLA-4 tail transgene were long lived with no evidence of multiorgan lymphocytic infiltration, but exhibited lymphadenopathy and accumulated large numbers of activated T cells. Furthermore, these animals displayed a Th2-biased phenotype which conferred susceptibility to Leishmania infection. These results indicate that the inhibitory effect of CTLA-4 is mediated in part through the ability of the extracellular domain to compete for ligands. The cytoplasmic domain of CTLA-4, however, is required for complete inhibitory function of the receptor and for regulation of Th cell differentiation in vivo.