Phase I and pharmacological study of cytarabine and tanespimycin in relapsed and refractory acute leukemia

BACKGROUND

In preclinical studies the heat shock protein 90 (Hsp90) inhibitor tanespimycin induced down-regulation of checkpoint kinase 1 (Chk1) and other client proteins as well as increased sensitivity of acute leukemia cells to cytarabine. We report here the results of a phase I and pharmacological study of the cytarabine + tanespimycin combination in adults with recurrent or refractory acute leukemia.

DESIGN AND METHODS

Patients received cytarabine 400 mg/m(2)/day continuously for 5 days and tanespimycin infusions at escalating doses on days 3 and 6. Marrow mononuclear cells harvested before therapy, immediately prior to tanespimycin, and 24 hours later were examined by immunoblotting for Hsp70 and multiple Hsp90 clients.

RESULTS

Twenty-six patients were treated at five dose levels. The maximum tolerated dose was cytarabine 400 mg/m(2)/day for 5 days along with tanespimycin 300 mg/m(2) on days 3 and 6. Treatment-related adverse events included disseminated intravascular coagulation (grades 3 and 5), acute respiratory distress syndrome (grade 4), and myocardial infarction associated with prolonged exposure to tanespimycin and its active metabolite 17-aminogeldanamycin. Among 21 evaluable patients, there were two complete and four partial remissions. Elevations of Hsp70, a marker used to assess Hsp90 inhibition in other studies, were observed in more than 80% of samples harvested 24 hours after tanespimycin, but down-regulation of Chk1 and other Hsp90 client proteins was modest.

CONCLUSIONS

Because exposure to potentially effective concentrations occurs only for a brief time in vivo, at clinically tolerable doses tanespimycin has little effect on resistance-mediating client proteins in relapsed leukemia and exhibits limited activity in combination with cytarabine. (Clinicaltrials.gov identifier: NCT00098423).

"Bridge population": sex workers or their clients?--STI prevalence and risk behaviors of clients of female sex workers in China

As the HIV/AIDS epidemic and the spread of sexually transmitted infections (STIs) in China has come to the forefront of public health attention, female sex workers (FSWs) and their clients (CFSWs) are becoming increasingly important to HIV/STI prevention efforts. This secondary analysis uses data abstracted from the Chinese Health and Family Life Survey 1999-2000 to report prevalence rates of two STIs as well as sexual risk behaviors for CFSWs - men who paid for sex with FSWs in the past 12 months - in comparison with men who had not patronized FSWs. Among 1879 Chinese CFSWs who completed anonymous interviews and urine testing, 152 (6.3%, weighted) said they had paid for sex in the past 12 months and 18.8% of CFSWs (weighted) tested positive for gonorrhea. CFSWs were 10 times more likely to have an STI (either self-reported or tested) than non-client Chinese men, and they were equally likely to use condoms inconsistently with their spouses. This study highlights the importance of studying CFSWs who use condoms inconsistently and do not practice safe sex with their spouse as a potential bridge population. Prevention and intervention efforts should target this bridge population and include education on HIV/AIDS and STI transmission, condom promotion, marriage counseling, destigmatization of HIV and STIs, and promotion of STI diagnosis and treatment.

FLT3 inhibitors in acute myeloid leukemia

The fms-like tyrosine kinase 3 (FLT3) plays an important role in both normal and malignant hematopoiesis. Activating mutations in the FLT3 receptor can be detected in approximately 30% of acute myeloid leukemias (AMLs) and are associated with a distinctly poor clinical outcome for patients. There are now several classes of FLT3 inhibitors in development with varying degrees of potency and selectivity for the target, including several in late-phase clinical trials in combination with chemotherapy. Major clinical responses in AML patients receiving single-agent FLT3 inhibitors have been rare, although transient peripheral blood blast reduction is common. Given such biological suggestion and preclinical activity, FLT3 inhibitors hold promise in improving the outcome of patients with mutant FLT3 AML. This review summarizes the current attempts to target this molecule, with emphasis on the validity of the target, the results of the clinical trials evaluating the FLT3 inhibitors in AML, the optimal use of these compounds and the mechanisms of resistance.

FLT3 ligand impedes the efficacy of FLT3 inhibitors in vitro and in vivo

We examined in vivo FLT3 inhibition in acute myeloid leukemia patients treated with chemotherapy followed by the FLT3 inhibitor lestaurtinib, comparing newly diagnosed acute myeloid leukemia patients with relapsed patients. Because we noted that in vivo FLT3 inhibition by lestaurtinib was less effective in the relapsed patients compared with the newly diagnosed patients, we investigated whether plasma FLT3 ligand (FL) levels could influence the efficacy of FLT3 inhibition in these patients. After intensive chemotherapy, FL levels rose to a mean of 488 pg/mL on day 15 of induction therapy for newly diagnosed patients, whereas they rose to a mean of 1148 pg/mL in the relapsed patients. FL levels rose even higher with successive courses of chemotherapy, to a mean of 3251 pg/mL after the fourth course. In vitro, exogenous FL at concentrations similar to those observed in patients mitigated FLT3 inhibition and cytotoxicity for each of 5 different FLT3 inhibitors (lestaurtinib, midostaurin, sorafenib, KW-2449, and AC220). The dramatic increase in FL level after chemotherapy represents a possible obstacle to inhibiting FLT3 in this clinical setting. These findings could have important implications regarding the design and outcome of trials of FLT3 inhibitors and furthermore suggest a rationale for targeting FL as a therapeutic strategy.

Have the bioavailabilities of trace metals to a suite of biomonitors changed over three decades in SW England estuaries historically affected by mining?

Many estuaries of southwest England were heavily contaminated with toxic metals associated with the mining of copper and other metals, particularly between 1850 and 1900. The question remains whether the passage of time has brought remediation to these estuaries. In 2003 and 2006 we revisited sites in 5 metal-contaminated estuaries sampled in the 1970s and 1980s - Restronguet Creek, Gannel, West Looe, East Looe and Tavy. We evaluate changes in metal contamination in sediments and in metal bioavailabilities in sediments and water to local organisms employed as biomonitors. We find that the decline in contamination in these estuaries is complex. Differences in bioavailable contamination in the water column were detectable, as were significant detectable changes in at least some estuaries in bioavailable metal contamination originating from sediments. However, in the 100 years since mining activities declined, bioavailable contamination has not declined to the regional baseline in any estuary affected by the mine wastes. The greatest decline in contamination occurred in the one instance (East Looe) where a previous industrial source of (Ag) contamination was considered. We used the macroalgae Fucus vesiculosus and Ascophyllum nodosum as biomonitors of dissolved metal bioavailabilities and the deposit feeders Nereis diversicolor and Scrobicularia plana as biomonitors of bioavailable metal in sediments. We found no systematic decrease in the atypically high Ag, Cu, Pb and Zn concentrations in the estuarine sediments over a 26 year period. Accumulated metal (Ag, As, Cu, Pb, and Zn) concentrations in the deposit feeders are similarly still atypically high in at least one estuary for each metal, and there is no consistent evidence for general decreases in sediment metal bioavailabilities over time. We conclude that the legacy of mining in sheltered estuaries of southwest England is the ongoing presence of sediments rich in metals bioavailable to deposit feeders, while dissolved metal bioavailabilities from this historical source alone are no longer atypically high.

Role of allogeneic transplantation for FLT3/ITD acute myeloid leukemia: outcomes from 133 consecutive newly diagnosed patients from a single institution

Acute myelogenous leukemia (AML) patients with FLT3/ITD mutations have an inferior survival compared to AML patients with wild-type (WT) FLT3, primarily because of an increased relapse rate. Allogeneic transplantation represents a postremission therapy that is effective at reducing the risk of relapse for many cases of poor-risk AML. Whether or not allogeneic transplantation in first complete remission (CR) can improve outcomes for patients with FLT3/ITD AML remains controversial. Our institution has adopted a policy of pursuing allogeneic transplantation, including the use of alternate donors, for FLT3/ITD AML patients in remission. As part of an instituional review board-approved study, we performed a review of the clinical data from November 1, 2004, to October 31, 2008, on all adult patients under the age of 60 presenting in consecutive fashion to the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins with newly diagnosed non-M3 AML. We followed their outcomes through August 1, 2010. During the study period, 133 previously untreated AML patients between the ages of 20 and 59 were diagnosed and received induction and consolidation therapy at our institution. Of these 133 patients, 31 (23%) harbored an FLT3/ITD mutation at diagnosis. The median overall survival (OS) from the time of diagnosis for the FLT3/ITD AML patients was compared to the OS of the entire cohort and found to be comparable (19.3 months versus 15.5 months, P = .56). Historically, OS for FLT3/ITD AML patients is significantly worse than for AML patients lacking this mutation. However, the OS for the 31 FLT3/ITD patients reported here was comparable to the 102 patients with WT FLT3 over the same 4-year time period. One difference that might have contributed to the surprising outcomes for the FLT3/ITD group is our aggressive pursuit of allogeneic bone marrow transplant (BMT) in CR1 within this group (60% of FLT3/ITD versus 17% with WT). Our single-institution study of consecutively treated AML patients supports the hypothesis that allogeneic transplant in early CR1 improves the long-term outcomes for FLT3/ITD AML.

NCCN Task Force report: tyrosine kinase inhibitor therapy selection in the management of patients with chronic myelogenous leukemia

The advent of imatinib has dramatically improved outcomes in patients with chronic myelogenous leukemia (CML). It has become the standard of care for all patients with newly diagnosed chronic-phase CML based on its successful induction of durable responses in most patients. However, its use is complicated by the development of resistance in some patients. Dose escalation might overcome this resistance if detected early. The second-generation tyrosine kinase inhibitors (TKIs) dasatinib and nilotinib provide effective therapeutic options for managing patients resistant or intolerant to imatinib. Recent studies have shown that dasatinib and nilotinib provide quicker and potentially better responses than standard-dose imatinib when used as a first-line treatment. The goal of therapy for patients with CML is the achievement of a complete cytogenetic response, and eventually a major molecular response, to prevent disease progression to accelerated or blast phase. Selecting the appropriate TKI depends on many factors, including disease phase, primary or secondary resistance to TKI, the agent's side effect profile and its relative effectiveness against BCR-ABL mutations, and the patient's tolerance to therapy. In October 2010, NCCN organized a task force consisting of a panel of experts from NCCN Member Institutions with expertise in the management of patients with CML to discuss these issues. This report provides recommendations regarding the selection of TKI therapy for the management of patients with CML based on the evaluation of available published clinical data and expert opinion among the task force members.

Characterization of chronic myeloid leukemia stem cells

Although tyrosine kinase inhibitors have redefined the care of chronic myeloid leukemia (CML), these agents have not proved curative, likely due to resistance of the leukemia stem cells (LSC). While a number of potential therapeutic targets have emerged in CML, their expression in the LSC remains largely unknown. We therefore isolated subsets of CD34(+) stem/progenitor cells from normal donors and from patients with chronic phase or blast crisis CML. These cell subsets were then characterized based on ability to engraft immunodeficient mice and expression of candidate therapeutic targets. The CD34(+)CD38(-) CML cell population with high aldehyde dehydrogenase (ALDH) activity was the most enriched for immunodeficient mouse engrafting capacity. The putative targets: PROTEINASE 3, SURVIVIN, and hTERT were expressed only at relatively low levels by the CD34(+)CD38(-)ALDH(high) CML cells, similar to the normal CD34(+)CD38(-)ALDH(high) cells and less than in the total CML CD34(+) cells. In fact, the highest expression of these antigens was in normal, unfractionated CD34(+) cells. In contrast, PRAME and WT1 were more highly expressed by all CML CD34(+) subsets than their normal counterparts. Thus, ALDH activity appears to enrich for CML stem cells, which display an expression profile that is distinct from normal stem/progenitor cells and even the CML progenitors. Indeed, expression of a putative target by the total CD34(+) population in CML does not guarantee expression by the LSC. These expression patterns suggest that PROTEINASE 3, SURVIVIN, and hTERT are not optimal therapeutic targets in CML stem cells; whereas PRAME and WT1 seem promising.

Acute myeloid leukemia is characterized by Wnt pathway inhibitor promoter hypermethylation

Nuclear localization of non-phosphorylated, active beta-catenin is a measure of Wnt pathway activation and is associated with adverse outcome in patients with acute myeloid leukemia (AML). While genetic alterations of the Wnt pathway are infrequent in AML, inhibitors of this pathway are silenced by promoter methylation in other malignanices. Leukemia cell lines were examined for Wnt pathway inhibitor methylation and total beta-catenin levels, and had frequent methylation of Wnt inhibitors and upregulated beta-catenin by Western blot and immunofluorescence. One hundred sixty-nine AML samples were examined for methylation of Wnt inhibitor genes. Diagnostic samples from 72 patients with normal cytogenetics who received standard high-dose induction chemotherapy were evaluated for associations between methylation and event-free or overall survival. Extensive methylation of Wnt pathway inhibitor genes was observed in cell lines, and 89% of primary AML samples had at least one methylated gene: DKK1 (16%), DKK3 (8%), RUNX3 (27%), sFRP1 (34%), sFRP2 (66%), sFRP4 (9%), sFRP5 (54%), SOX17 (29%), and WIF1 (32%). In contrast to epithelial tumors, methylation of APC (2%) and RASSF1A (0%) was rare. In patients with AML with normal cytogenetics, sFRP2 and sFRP5 methylation at the time of diagnosis was associated with an increased risk of relapse, and sFRP2 methylation was associated with an increased risk for death. In patients with AML: (a) there is a high frequency of Wnt pathway inhibitor methylation; (b) Wnt pathway inhibitor methylation is distinct from that observed in epithelial malignancies; and (c) methylation of sFRP2 and sFRP5 may predict adverse clinical outcome in patients with normal karyotype AML.

Abstract P4-11-15: Outcomes for Breast Cancer Patients with Isolated Metastasis or Recurrence to the Contralateral Nodal Basins

Background: Aggressive treatment of isolated breast cancer metastasis to either bone or lung has been reported to achieve long term survival. For the first time, we analyzed outcomes for patients (pts) with isolated metastasis to the contralateral (contra) supraclavicular (SCV) and/or axillary nodal basins.

Material and Methods: Pts treated with definitive or palliative radiation to the contra nodal basin(s) at M.D. Anderson were analyzed from the period of 2005-2010. They were divided into two groups: pts initially diagnosed with contra SCV and/or axilla as the only site of metastasis (designated Primary), and pts with recurrence in the contra SCV and/or axilla, without other distant metastasis (designated Recurrent).

Results: Of 34 potential pts with contra lymph node metastasis, 13 had isolated disease and were analyzed. In the Primary group (N=8, T4d N1- 3c M1), median survival was 25 mos, and 2-yr actuarial overall survivalwas 62.5%. All received neoadjuvant anthracycline and/or taxane-based chemotherapy followed by ipsilateral (ipsi) modified radical mastectomy and ipsi axillary lymph node dissection (ALND). The contra lymphatics were treated with ALND followed by radiation (N=5, 56-60 Gy) or with radiation alone (N=3, 45-66 Gy). Radiation fields included ipsi chest wall as well as ipsi and involved contra lymphatics. The contra chest wall or breast was radiated in 3 of the 8 pts. Two pts had estrogen receptor (ER) positive disease, and all had Her2-neu negative disease. Both ER+ pts are alive with no evidence of disease (NED; 1 had contra ALND; survival 25 and 51 mos). All 6 ER-pts died with disease (WD; 4 had contra ALND; survival 10 to 32 mos). One pt had an in-field recurrence in the contra nodal basin (51 Gy post ALND). No contra chest wall/breast recurrences were seen. All ER-pts developed additional distant metastasis, most within 4 mos of starting adjuvant radiation.

Regarding the Recurrent group (N=5), median survival was 25 mos after recurrence. Two ER+ pts received initial anti-estrogen therapy; all ER-pts initially received a taxane-based chemotherapy. The contra chest wall or breast was radiated in addition to the involved contra lymphatics in 3 of the 5 pts. Two pts had adjuvant radiation treatment with definitive intent to the contra lymphatics after ALND (50-50.4 Gy), with 1 alive/NED (66 mos from recurrence, no radiation to the contra breast) and 1 dead/WD (25 mos from recurrence). Radiation intent was palliation in 3 pts (none received ALND) with 1 alive/WD (60 Gy, 64 mos from recurrence) and 2 dead/WD (53.8 and 45 Gy, 6 and 18 mos from recurrence, respectively). In-field recurrence in the contra nodal basin occurred in 1 pt (50.4 Gy). Pts who died had progressive disease or additional distant metastasis within 3 mos of starting radiation.

Discussion: In this uncommon clinical scenario, locoregional control of the contra lymphatics was achieved with radiation alone or with surgery followed by radiation for a select group of pts; control was achieved without radiating the contra chest wall/breast. Only ER+ pts were rendered NED. Most ER-pts quickly developed other distant metastasis, highlighting the need for more effective systemic therapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-11-15.

Abstract P1-17-02: Outcome after Locoregional Recurrence in Patients with Inflammatory Breast Cancer

Purpose: High rates of locoregional recurrence (LRR) have been reported in spite of comprehensive tri-modality therapy for patients with inflammatory breast cancer (IBC). The aim of this study was to examine the prognosis of patients who have experienced LRR after treated primary IBC. Methods:

We retrospectively reviewed information for 124 IBC patients who experienced a LRR seen in our institution from 1990-2008. 63 patients had simultaneous distant disease (DM) +/−3 months of LRR (simLRR),

5 patients had LRR > 3 months subsequent to DM, while 56 patients had isolated LRR >3 months prior to DM (isLRR). Overall survival (OS) was calculated from date of recurrence using the Kaplan-Meier method. Results:

Median time to LRR from diagnosis was 13 months (interquartile range 8-21 months). Median survival after LRR was 15 months. 2-yr OS was 46%. Regarding the primary tumors, 23% were estrogen receptor positive (ER+), 33% were HER2-neu positive (H2N+), 81% had lymph vascular space invasion (LVSI), and 83% were grade 3. Comparing isLRR and simLRR cohorts, median survival was 18 months vs. 10 months and 2 yr-OS was 66% vs. 28%, respectively. ER+ and H2N+ primary status predicted for longer 2 yr OS among patients with simLRR but not among isLRR patients. (simLRR, ER+ 57% vs. ER-19% p = 0.02, H2N+ 45% vs. H2N-17% p = 0.01; IsLRR ER+ vs. ER-92% vs. 55% p = 0.15, H2N+ 86% vs. H2N-57% p = 0.11). LVSI was not prognostic in either group and Grade 3 primary trended towards worse outcome among isLRR cohort only, Grade 2 83% vs. Grade 3 64% P = 0.08. Molecular subtyping using ER and H2N status to group tumors demonstrates basal subtype in the primary tumor compared to H2N, luminal B and luminal A is associated with significantly worse 2 yr OS after isLRR (43% vs. 88%, 82%, and 83%, P = 0.04) and simLRR (13% vs. 34%, 80%, 32% P = 0.005) respectively. Conclusions:

Forty-five% of LRR occurred as isolated first events. LRRs generally occur within 2 years after primary IBC treatment and are associated with poor outcomes even as first events. Basal subtype predicts for worse overall survival regardless of distant disease.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-17-02.

Epigenetic differences in cytogenetically normal versus abnormal acute myeloid leukemia

BACKGROUND

Methylation of tumor suppression genes (TSGs) is common in myeloid malignancies. However, application of this as a molecular marker for risk stratification in patients with AML is limited.

DESIGN AND METHODS

To elucidate the impact of patterns of TSG methylation on outcome in cytogenetically normal patients, 106 samples from patients with having normal cytogenetic AML were evaluated for methylation of 12 genes by MSP. For sake of comparison, samples from patients with AML and abnormal cytogenetics (n = 63) were also evaluated.

RESULTS

Methylation frequencies in the whole group (n = 169) were similar to previous reports for CDH1 (31%), ER (31%), FHIT (9%), p15 (INK4b) (44%), p73 (25%), and SOCS1 (75%). Methylation of CTNNA1 was observed in 10%, CEBP-α in16%, CEBP-δ in 2%, MLH1 in 24%, MGMT in 11% and DAPK in 2% of AML samples. We find that DNA methylation was more prevalent in patients with normal compared to karyotypically abnormal AML for most genes; CEBPα (20% vs 9%), CTNNA1 (14% vs 4%), and ER (41% vs 19%) (p < 0.05 for all comparisons). In contrast, p73 was more frequently methylated in patients with karyotypic abnormalities (17% vs 38%; p < 0.05), perhaps due to specific silencing of the pro-apoptotic promoter shifting p73 gene expression to the anti-apoptotic transcript. In AML patients with normal cytogenetics, TSG methylation was not associated with event free or overall survival in a multivariate analysis.

CONCLUSIONS

In patients with AML, TSG methylation is more frequent in patients with normal karyotype than those with karyotypic abnormalities but does not confer independent prognostic information for patients with normal cytogenetics.

Urine catecholamine levels as diagnostic markers for neuroblastoma in a defined population: implications for ophthalmic practice

PURPOSE

although elevated urinary catecholamine levels have been reported in 90-95% of patients with neuroblastoma, more recent studies of pediatric Horner syndrome caused by an underling neuroblastoma have reported normal values at presentation. The purpose of this population-based study is to report the percentage of cases of neuroblastoma with elevated urinary catecholamine levels at presentation and to suggest a recommended work-up for cases of idiopathic pediatric Horner syndrome.

METHODS

the medical records of all pediatric (<19 years) residents of Olmsted County, Minnesota diagnosed with neuroblastoma from 1 January 1969 through 31 December 2008 were retrospectively reviewed.

RESULTS

a total of 14 patients <19 years of age were diagnosed with neuroblastoma as residents of Olmsted County, Minnesota, during the 40-year study period. A total of 10 (71%) of the 14 cases manifested elevated urinary catecholamine metabolites at the initial presentation. Urinary vanillylmandelic acid (VMA) levels were greater than twice the upper limit of normal in eight (57%) of 14 cases, whereas homovanillic acid (HVA) levels were greater than two times the upper limit of normal in 10 (71%) of the 14 cases. Three (75%) of the four cases without significantly elevated urinary VMA or HVA levels were diagnosed with stage IV disease, whereas one (25%) had stage II neuroblastoma.

CONCLUSION

urinary catecholamine levels were significantly elevated at presentation in 10 (71%) of the 14 neuroblastoma cases during the 40-year study period, suggesting that greater emphasis be placed on performing a thorough physical examination and obtaining warranted imaging studies in cases of idiopathic pediatric Horner syndrome.

Prevalence and risks for sexually transmitted infections among a national sample of migrants versus non-migrants in China

This study aims to describe and compare the gender-specific prevalence of chlamydia and gonorrhoea, sexual behaviours and experiences, and risk factors associated with sexually transmitted infections (STIs) among migrants versus rural and urban non-migrants in China. Data were abstracted from the Chinese Health and Family Life Survey conducted from 1999 to 2000, which provided a nationally representative adult (ages 20-64 years) sample. STI results were determined using a urine-based nucleic acid amplification assay. The prevalence of chlamydia for migrant women was triple that of rural non-migrant women. Migrants were more likely to engage in STI-associated risk behaviours than non-migrants (e.g. receiving money for sex). Among migrants, women were more likely than men to have STIs. The high STI prevalence among migrants highlights an urgent need to implement comprehensive prevention and intervention programmes targeting the cultural, social and structural needs of migrants in the city, especially migrant women.

Chenopodium as a prehistoric domesticate in eastern north america: evidence from russell cave, alabama

Approximately 50,000 carbonized fruits of the species Chenopodium berlandieri recovered from Russell Cave, Alabama, and dating to 1975 +/- 55 before the present, exhibit a set of interrelated morphological characteristics reflecting domestication (thin testa, truncate margin, rectanguloid fruit cross section, ligulate cotyledons, and increased internal fruit volume). These morphological characteristics establish the presence of a domestic variety of Chenopodium in the eastern United States by 2000 years ago.

Biodynamic modelling of the accumulation of Ag, Cd and Zn by the deposit-feeding polychaete Nereis diversicolor: inter-population variability and a generalised predictive model

Biodynamic parameters of the ragworm Nereis diversicolor from southern Spain and south England were experimentally derived to assess the inter-population variability of physiological parameters of the bioaccumulation of Ag, Cd and Zn from water and sediment. Although there were some limited variations, these were not consistent with the local metal bioavailability nor with temperature changes. Incorporating the biodynamic parameters into a defined biodynamic model, confirmed that sediment is the predominant source of Cd and Zn accumulated by the worms, accounting in each case for 99% of the overall accumulated metals, whereas the contribution of dissolved Ag to the total accumulated by the worm increased from about 27 to about 53% with increasing dissolved Ag concentration. Standardised values of metal-specific parameters were chosen to generate a generalised model to be extended to N. diversicolor populations across a wide geographical range from western Europe to North Africa. According to the assumptions of this model, predicted steady state concentrations of Cd and Zn in N. diversicolor were overestimated, those of Ag underestimated, but still comparable to independent field measurements. We conclude that species-specific physiological metal bioaccumulation parameters are relatively constant over large geographical distances, and a single generalised biodynamic model does have potential to predict accumulated Ag, Cd and Zn concentrations in this polychaete from a single sediment metal concentration.

Bioaccumulation of arsenic from water and sediment by a deposit-feeding polychaete (Arenicola marina): a biodynamic modelling approach

Arsenic bioaccumulation in the deposit-feeding polychaete Arenicola marina has been investigated using biodynamic modelling. Radiotracer techniques were used to determine the rates of uptake of As as arsenate from water and sediment and its subsequent efflux in the laboratory. Lugworms accumulated As from solution linearly at concentrations of 2-20 microg l(-1), with a corresponding uptake rate constant of 0.1648+/-0.0135 l g(-1)d(-1). 7.8+/-0.8% (assimilation efficiency) of the As ingested bound to sediments was retained after egestion of unassimilated metal. Elimination of As followed a two-compartment model, with mean efflux rate constants (from the slow pool) very similar for As accumulated from solution and ingested sediments (0.0449+/-0.0034 and 0.0478+/-0.0225 d(-1), respectively) and a corresponding biological half-time of roughly 15 d. A biodynamic model was constructed and validated through the comparison of biodynamic model predictions against measured bioaccumulated concentrations in lugworms from five UK estuaries. The model accurately predicted bioaccumulated As concentrations in lugworms using mean values of relevant physiological parameters (uptake rate, efflux rate and growth rate constants), a site-specific ingestion rate (calculated according to mean worm size and sediment organic matter content and expressed as the rate of ingestion of the mass of fine sediment), a site-specific sediment concentration measured after HCl extraction, and a standard dissolved As concentration. This combination of parameters showed that sediment ingestion contributed 30-60% of the total As accumulated by lugworms at the studied sites, depending on the different geochemistry at each site. This study showed that it is difficult to predict accurately As bioaccumulation at sites with different chemistries, unless that chemistry is taken into account.

Treatment options for patients with chronic myeloid leukemia who are resistant to or unable to tolerate imatinib

BACKGROUND

Imatinib has been found to substantially improve outcomes in patients with chronic myeloid leukemia (CML) compared with previously available therapies. However, its use is complicated by development of resistance or drug intolerance, prompting dose escalation or a trial of dasatinib or nilotinib, the second-generation tyrosine kinase inhibitors (TKIs).

OBJECTIVES

This article reviews the mechanisms of TKI resistance; discusses the tolerability and efficacy of high-dose imatinib, dasatinib, and nilotinib; and provides background for the rational use of second-line treatment options.

METHODS

MEDLINE (1966-December 2009) and EMBASE (1993-December 2009) were searched for pertinent English-language publications using search terms that included, but were not limited to, chronic myeloid leukemia, imatinib, dasatinib, nilotinib, and clinical trial. Abstracts from American Society of Hematology annual meetings (2005-2009) were also reviewed. There were no prespecified inclusion or exclusion criteria.

RESULTS

Major and complete cytogenetic responses (MCyR and CCyR, respectively) to second-line treatment with high-dose (600-800 mg/d PO) imatinib were restricted to CML patients who had achieved a CyR to standard-dose imatinib: >90% of patients without a previous CyR failed to respond. The expected durability of the response to this approach remains unclear. Grade 3/4 thrombocytopenia, neutropenia, and anemia occurred in 14%, 39%, and 8%, respectively, of patients receiving high-dose imatinib. In patients who failed first-line treatment with imatinib, dasatinib (70 mg BID PO) was associated with higher rates of CCyR at 2 years compared with imatinib (44% vs 18%, respectively; P = 0.003), as well as higher estimated rates of progression-free survival at 2 years (86% vs 65%; P = 0.001). Dasatinib use was complicated by grade 3/4 thrombocytopenia and neutropenia in 57% and 63% of patients, respectively, and pleural effusion in 5%. Nilotinib treatment was effective in patients who were resistant to or unable to tolerate imatinib, with 46% and 58% achieving a CCyR and MCyR, respectively, at 2 years. Nilotinib use was complicated by grade 3/4 thrombocytopenia and neutropenia in 28% and 40% of patients, respectively, and QTc-interval prolongation in 1% to 10% of patients. Neither agent was clinically effective in patients with the common T315I mutation.

CONCLUSION

Dasatinib and nilotinib were effective and generally well tolerated as second-line treatments for CML patients with a suboptimal response to standard doses of imatinib or imatinib intolerance.

K562/GM-CSF immunotherapy reduces tumor burden in chronic myeloid leukemia patients with residual disease on imatinib mesylate

PURPOSE

Chronic myeloid leukemia (CML) can be responsive to T-cell-mediated immunity. K562/granulocyte macrophage-colony stimulating factor (GM-CSF) is a GM-CSF producing vaccine derived from a CML cell line that expresses several CML-associated antigens. A pilot study was developed to determine if K562/GM-CSF immunotherapy could improve clinical responses to imatinib mesylate (IM) in patients with chronic myeloid leukemia.

EXPERIMENTAL DESIGN

Patients with chronic phase CML who achieved at least a major cytogeneic response but remained with persistent, measurable disease despite one or more years on imatinib mesylate were eligible. Each was given a series of four vaccines administered in three-week intervals, with or without topical imiquimod, while remaining on a stable dose of imatinib mesylate. CML disease burden was measured serially before and after vaccination.

RESULTS

Nineteen patients were vaccinated, with a median duration of previous imatinib mesylate therapy of 37 (13-53) months. Mean PCR measurements of BCR-ABL for the group declined significantly following the vaccines (P = 0.03). Thirteen patients had a progressive decline in disease burden, 8 of whom had increasing disease burden before vaccination. Twelve patients achieved their lowest tumor burden measurements to date following vaccine, including seven subjects who became PCR-undetectable.

CONCLUSIONS

K562/GM-CSF vaccine appears to improve molecular responses in patients on imatinib mesylate, including achieving complete molecular remissions, despite long durations of previous imatinib mesylate therapy.

What are the endpoints of therapy for acute leukemias? Old definitions and new challenges

Acute leukemias are complex diseases on multiple levels, and laboratory efforts over the past 3 decades have focused on better understanding of the molecular underpinnings and their stem cell biology. We now have a panoply of technologic advances that allow us to characterize individual leukemias by molecular profiles that relate directly to clinical behavior, to detect minimal residual disease, and to begin to develop "targeted" therapeutic strategies based on molecular considerations. There are a number of challenges surrounding this task: first, how to combine these agents with traditional chemotherapeutics and/or with each other to maximize leukemic cell kill and increase the cure rate; second, how to use these targeted agents in the minimal residual disease with potential curative intent; third, for patients unable to tolerate or unlikely to benefit from aggressive approaches, how to use one or more of these agents to reduce tumor bulk and either permit some restoration of normal marrow function or induce morphologic and functional differentiation of the leukemic clone to overcome the leukemia-associated bone marrow failure; and lastly, how to measure the effects of these agents on the molecular and cellular biologic levels in ways that correlate with and might even predict overall clinical outcome. These challenges are further complicated by the inherent heterogeneity in host biology; disease etiology and biology; and interactions among host, disease, and treatment that ultimately determine individual clinical outcomes. Toward this end, we will discuss selected issues surrounding new clinical trial designs and the development of clinically relevant molecular endpoints that might facilitate the development of new treatment approaches that will improve the outlook for adults with acute leukemias.

Protein kinase Cbeta modulates ligand-induced cell surface death receptor accumulation: a mechanistic basis for enzastaurin-death ligand synergy

Although treatment with the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) is known to protect a subset of cells from induction of apoptosis by death ligands such as Fas ligand and tumor necrosis factor-alpha-related apoptosis-inducing ligand, the mechanism of this protection is unknown. This study demonstrated that protection in short term apoptosis assays and long term proliferation assays was maximal when Jurkat or HL-60 human leukemia cells were treated with 2-5 nm PMA. Immunoblotting demonstrated that multiple PKC isoforms, including PKCalpha, PKCbeta, PKCepsilon, and PKC, translocated from the cytosol to a membrane-bound fraction at these PMA concentrations. When the ability of short hairpin RNA (shRNA) constructs that specifically down-regulated each of these isoforms was examined, PKCbeta shRNA uniquely reversed PMA-induced protection against cell death. The PKCbeta-selective small molecule inhibitor enzastaurin had a similar effect. Although mass spectrometry suggested that Fas is phosphorylated on a number of serines and threonines, mutation of these sites individually or collectively had no effect on Fas-mediated death signaling or PMA protection. Further experiments demonstrated that PMA diminished ligand-induced cell surface accumulation of Fas and DR5, and PKCbeta shRNA or enzastaurin reversed this effect. Moreover, enzastaurin sensitized a variety of human tumor cell lines and clinical acute myelogenous leukemia isolates, which express abundant PKCbeta, to tumor necrosis factor-alpha related apoptosis-inducing ligand-induced death in the absence of PMA. Collectively, these results identify a specific PKC isoform that modulates death receptor-mediated cytotoxicity as well as a small molecule inhibitor that mitigates the inhibitory effects of PKC activation on ligand-induced death receptor trafficking and cell death.

NCCN task force report: molecular markers in leukemias and lymphomas

The introduction of targeted therapies has revolutionized treatment and improved outcomes in patients with leukemias and lymphomas. However, many patients experience relapse caused by the persistence of residual malignant cells. Cytogenetic and molecular techniques are increasingly being used to assess and quantify minimal residual disease (MRD). The emergence of advanced technologies has led to the discovery of multiple novel molecular markers that can be used to detect MRD and predict outcome in patients with leukemias and lymphomas. Gene expression signatures that predict clinical outcomes in patients with non-Hodgkin's lymphoma have been identified. In chronic myelogenous leukemia, molecular monitoring has become more important in assessing response and detecting resistance to therapy. In acute leukemias, several new markers have shown potential in prognostication and monitoring treatment. In leukemias and lymphomas, microRNAs have been identified that may be useful in diagnostics and prognostication. To address these issues, the National Comprehensive Cancer Network (NCCN) organized a task force consisting of a panel of experts in leukemia and lymphoma to discuss recent advances in the field of molecular markers and monitoring MRD.