Stromal cells in haemopoiesis

Stromal cells of the bone marrow can provide the growth-promoting and differentiation-inducing molecules which are necessary for haemopoiesis. While the nature of these stimuli is largely unknown, the development of haemopoietic cells in association with stromal cells requires intimate cell contact. Molecules of the extracellular matrix, such as heparan sulphate, are able to bind growth factors and in this way the stromal cells may form microenvironmental niches which preferentially promote development of multipotent and committed cells along discrete lineages. Cells from some patients with acute and chronic myeloid and lymphoid leukaemias are defective in their ability to interact with stromal cells and consequently cannot survive in stromal cell-mediated long-term marrow cultures. We have exploited this phenomenon to obtain normal haemopoietic cells from patients with leukaemia, and to use these cells for successful autografting in patients with acute and chronic myeloid leukaemias.

Cadmium accumulation in the human retina: effects of age, gender, and cellular toxicity

Tobacco smoking and aging are among the few factors linked to age-related macular degeneration (AMD), a major cause of blindness in the elderly. Recent studies indicate that cadmium (Cd), an environmental toxic trace metal, is approximately four-fold higher in the retinas of smokers compared to non-smokers. In this study, we determined the effects of age and gender on Cd accumulation in human retinal tissues, specifically the neural retina, retinal pigment epithelium (RPE), and choroid. Cadmium levels in cultured RPE cells or retinal tissues isolated from frozen donor eyes were measured using inductively coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrophotometry (GF-AAS). Cadmium uptake in cultured human RPE cells (ARPE-19) was also assessed using GF-AAS. Toxic effects of cadmium were determined from cell loss (measured as a decrease in cell density) and lactate dehydrogenase release (an indicator of membrane disruption). In "young" eyes (< 55 years) Cd was highest in the retinal pigment epithelium and lowest in the neural retina. Cd was higher in all tissues in aged eyes (>or=55 years) and was significantly higher in the neural retina and RPE in older females. Cultured RPE cells exposed to Cd showed altered cell morphology, decreased cell survival, elevated ROS levels and concentration-dependent disruption of membrane integrity. We conclude that cadmium is accumulated differently in the neural retinal and RPE of older men and women. The deleterious effects of Cd on RPE cells indicate that this environmental toxin is a potentially important factor in age-related retinal disease.

Characteristics of a high-risk minority population

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Background: Black and Hispanic breast cancer patients have a worse outcome when compared to Caucasians. This could be due to socioeconomic, cultural or biologic factors. We hypothesized that host and tumor biologic characteristics associated with a poor outcome may be found more often in minority women. Methods: Race/ethnicity, menopausal status, tumor histological features, and patient characteristics including age and body mass index (BMI) were reviewed from a prospective neoadjuvant trial of docetaxel vs. doxorubicin/cyclophosphamide at Baylor College of Medicine Breast Center, from September 2002 to September 2006. The data were analyzed using Chi-square and Fisher's exact tests, while the Kruskal-Wallis method was used to analyze BMI. Results: Of the 167 patients, 63% (n=105) were Caucasian, 15% (n=26) were Hispanic and 22% (n=36) were Black. The mean age was 47.6 years (range: 30–72). Fifty-nine percent were premenopausal. Overall, mean BMI was 29, with Caucasians having a mean BMI of 27.5, Hispanics with 29.8 and Blacks with a BMI of 34.6 (P<0.001). Sixty-five percent of the Caucasians and 58% of Hispanics were ER+ or PR+ versus 44% of Blacks (P=0.09). Sixteen percent of Caucasians were HER-2 positive compared to 4% of Hispanics and 9% of Blacks (p=0.25). In addition, 22% of Caucasians and 38% of Hispanics were ER-, PR-, HER-2- compared to 50% of tumors from Blacks (p=0.007). There was a trend linking BMI and triple negative status in breast cancers, which did not achieve statistical significance (p=0.21). Conclusion: In this study we found that black and Hispanic women were more likely to be obese and have ER-, PR-, HER-2- tumor phenotypes, both of which have been associated with poorer outcomes. Ongoing studies are being performed to elucidate the link between clinical and biological characteristics and understand the underlying molecular mechanisms associated with these findings.

No significant financial relationships to disclose.

Identifying patients at high risk for neutropenic complications during chemotherapy for metastatic breast cancer (MBC) with doxorubicin or pegylated liposomal doxorubicin: Development of a prediction model

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Background: Despite the effectiveness of anthracycline (ACH) therapy in the adjuvant and MBC settings, neutropenic complications (NC) remain a common and often unpredictable problem. Consequences may include dose reductions or delays in chemotherapy, or hospitalization for fever or infection. This study describes the development of a cycle-based risk prediction model for NC during chemotherapy with traditional doxorubicin (DOX) or a pegylated liposomal formulation (PLD) for MBC. Methods: Data analyzed was from a randomized clinical trial of MBC patients (n=509), who received chemotherapy with DOX (60 mg/m2 every 3 wks) or PLD (50 mg/m2 every 4 wks) [O'Brien, 2004]. NC were defined as an absolute neutrophil count (ANC) = 1.5 x106 cells/L, febrile neutropenia or neutropenia with infection. Patient, treatment and hematological factors potentially associated with NC were evaluated. Factors with a p-value of ≤ 0.25 within a cycle were included in a generalized estimating equations (GEE) regression model. Using backward elimination, we derived a risk scoring algorithm (range 0–63) from the final reduced model. Results: Risk factors retained in the model included poor performance status, ANC = 2.0 × 106 cells/L at some point in the previous cycle, the first cycle of chemotherapy, DOX vs. PLD and older age. A precycle risk score from = 25 to < 40 for a given patient was identified as being the optimal threshold for sensitivity (58.0%) and specificity (78.7%). Patients with a score at or beyond this threshold would be considered at high risk for developing NC in later cycles. Risk scores below, within, or above this threshold predict a 0.3%–2%, 3%–8% and a 9%–45% probability risk of NC, respectively. Conclusion: This risk prediction tool demonstrated acceptable internal validity and can be readily applied by the clinician prior to a given cycle of chemotherapy. The application of this prediction tool may allow for identification and targeted intervention (such as growth factor support or the use of PLD) for those most likely to experience NC during anthracycline-based chemotherapy for MBC.

No significant financial relationships to disclose.

A genomic signature of chemotherapeutic multidrug resistance provides a rational approach to identify patients for targeted therapy in advanced solid tumors

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Background: Multidrug resistance (MDR), the process by which cells resist many structurally and functionally unrelated drugs, remains a major challenge for cancer treatment. Strategies to reliably predict MDR will revolutionize cancer therapy. Methods: We made use of in vitro drug sensitivity data on 47 FDA approved chemotherapeutic agents from the NCI-60 database coupled with Affymetrix microarray data, to develop a gene expression signature of chemotherapeutic MDR, using a 'metagene’ approach to gene expression analysis (Potti et al, Nature Medicine, 2006). The capacity of the MDR signature to predict in vitro and in vivo resistance was evaluated in multiple independent cell line and patient cohorts. Results: A gene expression signature of chemotherapeutic MDR developed from cancer cell lines using a novel ‘metagene’ approach can accurately predict patients resistant to standard chemotherapeutic agents, including multi-drug regimens. This includes cohorts of patients with early stage breast cancer (n = 171; accuracy: 75.5%, sensitivity: 49.3%, specificity: 92%), patients who received neoadjuvant chemotherapy (n = 51; accuracy: 78.5%, sensitivity: 73.7%, specificity: 92.3%), and ovarian cancer (n = 105; accuracy: 83.8%, sensitivity: 71.8%, specificity: 93.7%). We further show that MDR signature expression is an independent prognostic factor in early stage breast cancer (p = 0.02, odds ratio: 3.49) and a large cohort of non-small cell lung cancer (p = 0.03, odds ratio: 5.70), in a multivariate analysis. Finally, to identify a rational therapeutic strategy in patients with the MDR phenotype, we have integrated the prediction of MDR with profiles of oncogenic pathway deregulation (Bild A, Nature, 2006) and show that targeting the Src pathway using a Src specific inhibitor (SU6656) circumvents MDR in the in vitro setting. Conclusions: The development of a gene expression signature of MDR, that can predict resistance to commonly used cytotoxic chemotherapies, provides a rational approach to developmental therapeutics, by identifying novel 'customized’ candidate drugs (e.g. targeting Src) for further clinical development.

No significant financial relationships to disclose.

Polymorphisms of 5,10-methylenetetralydrofolate reductase (MTHFR), fruit and vegetable intake, and the risk of stomach cancer

Stomach cancer is a serious public health problem in China. 5,10-Methylenetetralydrofolate reductase (MTHFR) may be involved in both DNA methylation and DNA synthesis. Folate deficiency is associated with cancer risk that may be modulated by a genetic variation in the MTHFR gene in folate metabolism. The main goal of this study was to evaluate the association between polymorphisms of the MTHFR gene and the risk of stomach cancer. This study also explored the modification effects of fruit and vegetable intake (one of the main constituents is folate) on the risk of this disease. A population-based case-control study was conducted in Taixing, China, consisting of 206 newly diagnosed cases with primary stomach cancer and 415 healthy population controls. Polymorphisms of MTHFR C677T and A1298C were assayed by polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) techniques. The data were analysed using the logistic regression model. No obvious association between the MTHFR A1298C polymorphism and the risk of stomach cancer was observed in this study. The frequencies of 677 C/C, C/T, and T/T were 34.5, 50.9, and 14.6%, respectively, in controls. The frequency of the MTHFR 677 wild homozygotic genotype was 25.8% in cases, which was lower than that in controls (34.5%). The adjusted odds ratio (OR) for the MTHFR 677 any T genotype was 2.05 (95% confidence interval (CI), 1.26-3.34) when compared with the C/C genotype. In the low fruit and vegetable intake group an increasing trend was observed with the T allele exposure, p = 0.0056. The adjusted ORs were 1.68 (95% CI = 0.86-3.29) for the C/T genotype and 3.58 (95% CI = 1.46-8.75) for the T/T genotype, respectively. The MTHFR 677 any T genotype was associated with an increased risk of primary stomach cancer among the Chinese population. Folate deficiency might modify the MTHFR gene polymorphism and influence the risk of stomach cancer.

Use of MR spectroscopy and functional imaging in the treatment planning of gliomas

Routine anatomical imaging with CT and MRI does not reliably indicate the true extent or the most malignant areas of gliomas and cannot identify the functionally critical parts of the brain. The aim of the study was to see if the use of MR spectroscopic imaging (MRSI) along with functional MRI (fMRI) can better define both the target and the critical structures to be avoided to improve radiation delivery in gliomas. 12 patients with gliomas underwent multivoxel MRS and functional imaging using GE processing software. The choline to creatine ratio (Cho:Cr), which represents the degree of abnormality for each individual voxel on MRSI, was derived, converted into a grayscale grading system, fused to the MRI images and then transferred to the planning CT images. An intensity-modulated radiation therapy (IMRT) plan was developed using the dose constraints based on both the anatomical and the functionally critical regions. Cho:Cr consistently identified the gross tumour volume (GTV) within the microscopic disease (clinical target volume, CTV) and allowed dose painting using IMRT. No correlation between MRSI based Cho:Cr > or =2 and MR defined CTV nor their location was noted. However, MRSI defined Cho:Cr > or =3 was smaller by 40% compared with post-contrast T1 weighted MRI defined GTV volumes. fMRI helped in optimizing the orientation of the beams. In conclusion, both MRSI and fMRI provide additional information to conventional imaging that may guide dose painting in treatment planning of gliomas. A Phase I IMRT dose intensification trial in gliomas using this information is planned.

Active CMV disease does not always correlate with viral load detection

The use of quantitative cytomegalovirus (CMV) real-time polymerase chain reaction (RT-PCR) and preemptive ganciclovir therapy is replacing prophylaxis as the management of choice in high-risk patients undergoing stem cell transplantation (SCT). However, there are limited data defining its role in this setting. In the current retrospective single-centre study, quantitative RT-PCR was used to determine CMV in 577 consecutive patients undergoing SCT (172 allogeneic and 405 autologous) over a 5-year period. CMV RT-PCR was performed weekly until cessation of immunosuppression (allogeneic) or for 30 days post-SCT (autologous). Treatment was commenced after two consecutive positive results or a high copy on the first occasion (> 1000 copies/ml, > 3 log). The overall CMV reactivation rate in patients undergoing allogeneic SCT was 30%, with reactivation observed in 72% of high-risk patients (recipient positive patients). CMV end-organ disease was observed in eight patients (1%); of these, four were CMV RT-PCR negative at the time of diagnosis of end-organ CMV disease, with three remaining negative throughout the course of the disease. CMV-related mortality was recorded in three patients. The current data support a preemptive treatment strategy-based CMV RT-PCR, but indicate that in symptomatic patients, a negative CMV PCR result does not exclude CMV end-organ disease.