Efficacy of different dosing schedules of capecitabine for metastatic breast cancer: a single-institution experience.

Purpose Capecitabine is widely used as a single agent on a 21-day cycle in the management of metastatic breast cancer (MBC). Our primary objective was to compare the standard dosing of capecitabine (Arm A: days 1-14 on 21-day cycle) to biweekly dosing (Arm B: days 1-7 and 15-21 on 28-day cycle) using retrospective data analysis. Methods 166 patients with MBC treated with single agent capecitabine at The Ohio State University from 2002 to 2014 were considered eligible. Median time to treatment failure (TTF) and overall survival (OS) were estimated using Kaplan-Meier (KM) methods. KM curves were compared using log-rank tests with Holm's correction for multiplicity. Results Patients were grouped by dose schedule into one of three arms: Arm A (21-day cycle; capecitabine given at 1000 mg/m2 orally, twice daily on days 1-14 of 21-day cycle); Arm B (28-day cycle; capecitabine given at 1000 mg/m2 orally, twice daily on days 1-7 and 15-21 of 28-day cycle); and Arm C (changeover regimen where patients started on the 21-day cycle, but changed to a 28-day cycle for tolerability). No difference was found in TTF or OS for patients with MBC between those who received capecitabine on either standard dosing (Arm A) and those on a biweekly cycle (Arm B or C). Overall, 41% of patients required dose reduction. Conclusions Our single institution experience showed that alternate dosing of capecitabine (biweekly, 28-day cycle) may be a reasonable alternative to standard 21-day cycle with similar efficacy and fewer dose reductions.

A phase I study of an oral selective gamma secretase (GS) inhibitor RO4929097 in combination with neoadjuvant paclitaxel and carboplatin in triple negative breast cancer.

Upregulation of Notch pathway is associated with poor prognosis in breast cancer. We present the results of a phase I study of an oral selective gamma secretase (GS) inhibitor (critical to Notch signaling), RO4929097 in combination with neoadjuvant chemotherapy for operable triple negative breast cancer. The primary objective was to determine the maximum tolerated dose (MTD) of RO4929097. Secondary objectives were to determine real-time pharmacokinetics of RO4929097 and paclitaxel, safety and pathologic (pCR) complete response to study treatment. Eligible patients, initiated carboplatin at AUC 6 administered intravenously (IV) on day 1, weekly paclitaxel at 80 mg/m2 IV and RO4929097 10 mg daily given orally (PO) on days 1-3, 8-10 and 15-17 for six 21-day cycles. RO4929097 was escalated in 10 mg increments using the 3 + 3 dose escalation design. Two DLTs were observed in 14 patients - Grade (G) 4 thrombocytopenia in dose level 1 (10 mg) and G3 hypertension in dose level 2 (20 mg). Protocol-defined MTD was not determined due to discontinuation of RO4929097 development. However, 4 of 5 patients enrolled to 20 mg dose of RO4929097 required dose reduction to 10 mg due to toxicities (including neutropenia, thrombocytopenia and hypertension) occurring during and beyond the DLT observation period. Thus, 10 mg would have been the likely dose level for further development. G3 or higher hematologic toxicities included neutropenia (N = 8, 57%) and thrombocytopenia (N = 5, 36%) patients. Six (43%) patients had G2-3 neuropathy requiring paclitaxel dose reduction. No signs of drug-drug interaction between paclitaxel and RO4929097 were evident. Five patients (36%) had pCR.

Posttraumatic stress in breast cancer survivors diagnosed at a young age.

OBJECTIVE: Young breast cancer patients experience greater psychosocial distress compared with older patients, which raises concern for their risk of posttraumatic stress disorder (PTSD). We sought to characterize the prevalence of clinically significant symptoms of PTSD and associated factors among breast cancer survivors diagnosed at a young age. METHODS: The Young Women's Breast Cancer Study, an ongoing prospective cohort study, enrolled 1302 women diagnosed with breast cancer at age ≤ 40 between 2006 and 2016. Participants complete serial surveys, and we obtained additional information from medical record review. Socio-demographics, anxiety and depression, social support, and psychiatric co-morbidities and medications were assessed at study baseline (median, 5 months post-diagnosis). We defined a participant as having clinically significant posttraumatic stress symptoms (PTSS) by scoring ≥50 on the PTSD Checklist-Specific Version, administered on the 30-month survey. RESULTS: Among 700 women with stage 1-3 disease, the prevalence of PTSS was 6.3% (95%CI = 4.5-8.1). In multivariable analyses, PTSS was significantly associated with anxiety (OR 12.43, 95%CI = 5.81-26.59, P < .0001) and stage 2 vs 1 disease (OR 2.26, 95%CI = 1.04-4.93, P = .04). PTSS was inversely associated with having a college degree (OR 0.29, 95%CI = 0.13-0.62, P = .002) and greater social support (OR 0.44, 95%CI = 0.21-0.94, P = .03). CONCLUSIONS: We found similar rates of cancer-related PTSS in breast cancer survivors diagnosed at a young age compared with the general breast cancer population despite their well-documented increased risk of overall distress. Nevertheless, factors associated with posttraumatic stress should be considered at diagnosis and in survivorship to identify young patients who may benefit from psychosocial resources.

The impact of granulocyte colony-stimulating factor use in patients with metastatic breast cancer treated with palliative chemotherapy: a single-institution retrospective review.

PURPOSE: The goal of chemotherapy for metastatic breast cancer (MBC) is palliation of symptoms while minimizing treatment-related toxicities. It remains unclear whether use of granulocyte colony-stimulating factor (G-CSF) to maintain relative dose intensity of chemotherapy for MBC is associated with improved clinical outcomes. METHODS: The medical records of MBC patients treated with chemotherapy in 1st-3rd-line settings between May 2010 and April 2014 were reviewed. Time to progression (TTP), progression-free survival (PFS), and overall survival (OS) were compared between patients who received G-CSF and those who did not. Antibiotic use, total clinic visits, and pre- and post-treatment Eastern Cooperative Oncology Group (ECOG) performance status were also compared between the groups. RESULTS: Of the 169 patients included, 55 (32.5%) received > 1 G-CSF dose and 114 (67.5%) did not receive any G-CSF. The median TTP was similar between the two groups (5.0 months (95% CI 3.4-7.1) vs. 5.2 months (95% CI 4.8-6.2) respectively; p = 0.998). The median PFS (p = 0.955; 5.0 months (95% CI 3.4-5.9) vs. 5.2 months (95% CI 4.7-6.0), respectively) and OS (14.6 (95% CI 9.0-26.6) vs. 18.5 months (95% CI 15.2-22.0) in G-CSF and non-G-CSF groups, respectively; p = 0.628) were also similar between groups. No significant between-group differences were noted in rate of decline in ECOG performance status, antibiotic use, and number of clinic visits and hospitalizations. CONCLUSION: This retrospective analysis did not find any evidence that the use of G-CSF to maintain chemotherapy dose intensity for the treatment of MBC improves TTP, PFS, and OS or results in improved ECOG performance status compared with lack of G-CSF use in patients with MBC treated in 1st to 3rd-line settings.

Assessment of outcomes and novel immune biomarkers in metaplastic breast cancer: a single institution retrospective study.

BACKGROUND: Metaplastic breast cancer remains poorly characterized given its rarity and heterogeneity. The majority of metaplastic breast cancers demonstrate a phenotype of triple-negative breast cancer; however, differences in clinical outcomes between metaplastic breast cancer and triple-negative breast cancer in the era of third-generation chemotherapy remain unclear. METHODS: We compared the clinical outcomes between women with metaplastic breast cancer and women with triple-negative breast cancer diagnosed between 1994 and 2014. Metaplastic breast cancer patients were matched 1:3 to triple-negative breast cancer patients by stage and age at diagnosis. Distant disease-free survival (DDFS) and overall survival (OS) were estimated using Kaplan Meier methods and Cox proportional hazard regression models. Immune checkpoint markers were characterized by immunohistochemistry in a subset of samples. RESULTS: Forty-four metaplastic breast cancer patients (stage I 14%; stage II 73%; stage III 11%; stage IV 2%) with an average age of 55.4 (± 13.9) years at diagnosis. Median follow-up for the included metaplastic breast cancer and triple-negative breast cancer patients (n = 174) was 2.8 (0.1-19.0) years. The DDFS and OS between matched metaplastic breast cancer and triple-negative breast cancer patients were similar, even when adjusting for clinical covariates (DDFS: HR = 1.64, p = 0.22; OS: HR = 1.64, p = 0.26). Metaplastic breast cancer samples (n = 27) demonstrated greater amount of CD163 in the stroma (p = 0.05) and PD-L1 in the tumor (p = 0.01) than triple-negative breast cancer samples (n = 119), although more triple-negative breast cancer samples were positive for CD8 in the tumor than metaplastic breast cancer samples (p = 0.02). CONCLUSIONS: Patients with metaplastic breast cancer had similar outcomes to those with triple-negative breast cancer based on DDFS and OS. The immune checkpoint marker profile of metaplastic breast cancers in this study may prove useful in future studies attempting to demonstrate an association between immune profile and survival.

Treatment versus Punishment: Understanding Racial Inequalities in Drug Policy.

CONTEXT: Many observers believe that the policy response to the opioid crisis is less punitive than the crack scare and that the reason is that victims are (stereotypically) white. METHODS: To assess this conjecture, we compile new longitudinal data on district-level drug-related deaths and (co)sponsorship of legislation on drug abuse in the House of Representatives over the past four decades. Using legislator fixed effects models, we then test how changes in drug-related death rates in legislators' districts predict changes in (co)sponsorship of treatment-oriented or punitive legislation in the subsequent year and assess whether these relationships vary by race of victim or drug type. FINDINGS: Policy makers were more likely to introduce punitive drug-related bills during the crack scare and are more likely to introduce treatment-oriented bills during the current opioid crisis. The relationship between district-level drug deaths and subsequent sponsorship of treatment-oriented legislation is greater for opioid deaths than for cocaine-related deaths and for white victims than for black victims. By contrast, district-level drug deaths are not significantly related to sponsorship of punishment-oriented bills. CONCLUSIONS: These results suggest that the racial inequalities and double standards of drug policy still persist but in different forms.

A pilot videoconference group stress management program in cancer survivors: lessons learned.

CONTEXT: Cancer is a challenging experience and there is evidence that psychosocial interventions are effective at improving adjustment following treatment. At our cancer center, 14 cancer survivors (breast, prostate and blood cancers) completed a four-session cognitive-behavioral stress program. The first session was delivered at the survivor's local cancer center, where they were provided with a loaner tablet. The three subsequent sessions were delivered through group-based videoconference on the tablet. Session content was supplemented with a tailored ebook, designed specifically for this program. Participants provided feedback about the program as well as a standardized measure of perceived stress. ISSUES: Despite evidence that psychosocial programs are effective, there are significant barriers to dissemination, particularly for those residing in rural areas who do not live near academic medical centers where such programming is more readily available. Our experiences delivering a group-based videoconference program in cancer survivors are described, including positives and challenges associated with its design and implementation. LESSONS LEARNED: Study participants enrolled from across four different US states, and the majority reported at least a 30-minute commute to their cancer center. This travel burden played a meaningful role in their desire to participate in our videoconference-based program. Although participants reported that session content was well suited to addressing stress management concerns, and session facilitators were able to effectively teach program techniques (eg progressive muscle relaxation, cognitive-reframing) and that the program was helpful overall, only modest improvements in perceived stress were seen. Participants noted challenges of the delivery including feeling disconnected from others, difficulty focusing, technical problems, and a desire for a longer program. Thus, although the novel delivery of a group-based, psychosocial program using tablet videoconference is feasible in a survivorship program, and desired by cancer survivors, key improvements must be made in future efforts. Our enthusiasm about the potential of telehealth must be tempered with the reality that such delivery can present challenges that interfere with the intervention implementation and efficacy. Facilitators must proactively address both the technological and interpersonal challenges associated with the use of group-based videoconference in order to improve its ability to positively impact cancer survivors. Many of these issues can be resolved prior to program launch, and require foresight and planning on the part of the program team.

Partner support and anxiety in young women with breast cancer.

OBJECTIVE: Using a large prospective cohort of women age 40 or younger diagnosed with breast cancer, we examined the relationship between perceived partner support and anxiety. METHODS: Six hundred seventy-five young women with breast cancer Stages I-III, median age 36, completed a self-report baseline questionnaire. Perceived partner support was assessed using items extracted from the marital subscale of the Cancer Rehabilitation Evaluation System; generalized social support was assessed with the Medical Outcomes Study-Social Support Survey. Anxiety was measured using the anxiety subscale of the Hospital Anxiety and Depression Scale. Multivariable logistic regression analyses evaluated the association between partner support, other sociodemographic factors, and anxiety. RESULTS: Mean age at diagnosis was 35.4 years. Fourteen percent of the women were not partnered, and among those who were partnered or in a significant relationship, 20% were categorized as unsupported. In univariate and multivariable analysis adjusting for sociodemographic factors, women in an unsupported-partnered relationship had higher odds of anxiety symptoms compared with women in a supported-partnered relationship. Young age and being financially insecure were also both independently associated with anxiety. CONCLUSIONS: Our findings suggest that partner support may play a key role in a young woman's adjustment to a serious stressor such as breast cancer. In addition, younger age increases vulnerability to anxiety as does struggling with finances. Because supportive efforts of a partner have potential to protect against the impact of stress, interventions to enhance partner support and reduce anxiety might be beneficial to address challenges experienced as a couple in this setting.

Outpatient portal use among pregnant individuals: Cross-sectional, temporal, and cluster analysis of use.

Background: Outpatient portal technology can improve patient engagement. For pregnant individuals, the level of engagement could have important implications for maternal and infant outcomes. Objective: This study: (1) cross-sectionally and temporally characterized the outpatient portal use among pregnant individuals seen at our academic medical center; and (2) identified clusters of the outpatient portal user groups based on the cross-sectional and temporal patterns of use. Methods: We used outpatient portal server-side log files to execute a hierarchical clustering algorithm to group 7663 pregnant individuals based on proportions of outpatient portal function use. Post-hoc analyses were performed to further assess outpatient portal use on key encounter characteristics. Results: The most frequently used functions were MyRecord (access personal health information), Visits (manage appointments), Messaging (send/receive messages), and Billing (view bills, insurance information). Median outpatient portal function use plateaued by the third trimester. Four distinct clusters were identified among all pregnant individuals: "Schedulers," "Resulters," "Intense Digital Engagers," and "Average Users." Post-hoc analyses revealed that the use of the Visits function increased and the use of the MyRecord function decreased over time among clusters. Conclusions: Our identification of distinct cluster groups of outpatient portal users among pregnant individuals underscores the importance of avoiding the use of generalizations when describing how such patients might engage with patient-facing technologies such as an outpatient portal. These results can be used to improve user experience and training with outpatient portal functions and may educate maternal health providers on patient engagement with the outpatient portal.

Outpatient portal use in prenatal care: differential use by race, risk, and area social determinants of health.

To report the relationship of outpatient portal (OPP) use with clinical risk, area social determinants of health (SDoH), and race/ethnicity among pregnant women. Regression models predicting overall and individual portal feature use (main effects and interactions) based on key variables were specified using log files and clinical data. Overall OPP use among non-Hispanic Black women or patients who lived in lower SDoH neighborhoods were significantly less. High-risk pregnancy patients were likely to use the OPP more than those with normal-risk pregnancy. We found similar associations with individual OPP features, like Visit (scheduling) and My Record (test results). We also found significant interactive associations between race/ethnicity, clinical risk, and SDoH. Non-Hispanic Black women and those living in lower SDoH areas used OPP less than non-Hispanic White women from similar or affluent areas. More research must be conducted to learn of OPP use implications for pregnant women with specific clinical diagnoses.

Assessment of Leptomeningeal Carcinomatosis Diagnosis, Management and Outcomes in Patients with Solid Tumors Over a Decade of Experience.

OBJECTIVE: Leptomeningeal carcinomatosis (LMC), a common complication of advanced malignancies, is associated with high morbidity and mortality, yet diagnosis and treatment decisions remain challenging. This study describes the diagnostic and treatment modalities for LMC and identifies factors associated with overall survival (OS). MATERIALS AND METHODS: We performed a single-institution retrospective study (registration #: OSU2016C0053) of 153 patients diagnosed with LMC treated at The Ohio State University, Comprehensive Cancer Center, (OSUCCC)-James between January 1, 2010 and December 31, 2015. RESULTS: Median age at diagnosis was 55.7 years, and 61% had Eastern Cooperative Oncology Group baseline performance status ≤1. Most common primary tumors were breast (43%), lung (26%), and cutaneous melanoma (10%). At presentation, most patients were stage III-IV (71%) with higher grade tumors (grade III: 46%). Metastases to bone (36%), brain (33%), and lung (12%) were the most common sites with a median of 0.5 years (range, 0-14.9 years) between the diagnosis of first metastasis and of LMC. 153 (100%) patients had MRI evidence of LMC. Of the 67 (44%) who underwent lumbar puncture (LP), 33 (22%) had positive cerebrospinal fluid (CSF) cytology. Most patients received radiotherapy for LMC (60%) and chemotherapy (93%) for either the primary disease or LMC. 28 patients received intrathecal chemotherapy, 22 of whom had a primary diagnosis of breast cancer. 98% died with median OS of all patients was 1.9 months (95% CI: 1.3-2.5 months). CONCLUSION: Despite improved treatments and targeted therapies, outcomes of LMC remain extremely poor. Positive CSF cytology was associated with lower OS in patients who had cytology assessed and specifically in patients with breast cancer. CSF cytology serves as an important indicator for prognosis and helps aid in developing individualized therapeutic strategies for patients with LMC.

Iron uptake from plasma transferrin by a transferrin receptor 2 mutant mouse model of haemochromatosis.

BACKGROUND & AIMS: Hereditary haemochromatosis type 3 is caused by mutations in transferrin receptor (TFR) 2. TFR2 has been shown to mediate iron transport in vitro and regulate iron homeostasis. The aim of this study was to determine the role of Tfr2 in iron transport in vivo using a Tfr2 mutant mouse. METHODS: Tfr2 mutant and wild-type mice were injected intravenously with (59)Fe-transferrin and tissue (59)Fe uptake was measured. Tfr1, Tfr2 and ferroportin expression was measured by real-time PCR and Western blot. Cellular localisation of ferroportin was determined by immunohistochemistry. RESULTS: Transferrin-bound iron uptake by the liver and spleen in Tfr2 mutant mice was reduced by 20% and 65%, respectively, whilst duodenal and renal uptake was unchanged compared with iron-loaded wild-type mice. In Tfr2 mutant mice, liver Tfr2 protein was absent, whilst ferroportin protein was increased in non-parenchymal cells and there was a low level of expression in hepatocytes. Tfr1 expression was unchanged compared with iron-loaded wild-type mice. Splenic Tfr2 protein expression was absent whilst Tfr1 and ferroportin protein expression was increased in Tfr2 mutant mice compared with iron-loaded wild-type mice. CONCLUSIONS: A small reduction in hepatic transferrin-bound iron uptake in Tfr2 mutant mice suggests that Tfr2 plays a minor role in liver iron transport and its primary role is to regulate iron metabolism. Increased ferroportin expression due to decreased hepcidin mRNA levels is likely to be responsible for impaired splenic iron uptake in Tfr2 mutant mice.

Clinical impact of interruption in adjuvant Trastuzumab therapy in patients with operable HER-2 positive breast cancer.

BACKGROUND: Trastuzumab-induced cardiotoxicity (TIC) can lead to early discontinuation of adjuvant therapy, however there is limited evidence on long-term survival outcomes in patients with operable human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) experiencing treatment interruption or discontinuation. METHODS: The primary objective of the study was to evaluate disease-free survival (DFS) in non-metastatic, HER2-positive, female BC patients who experienced treatment interruption or early discontinuation of trastuzumab therapy. Clinical and histopathological data were collected on 400 patients at The Ohio State University, an NCI-designated comprehensive cancer center between January 2005 and December 2015. Treatment interruption was defined as any delay of ≥2 weeks during trastuzumab therapy, including permanent cessation prior to completing planned therapy. TIC was defined as LVEF < 50% or > 15 points decline from baseline as evaluated by 2D echocardiogram after initiation of (neo) adjuvant therapy. DFS was defined as the time from diagnosis to first recurrence (loco-regional or distant recurrence) including second primary BC or death. Overall survival (OS) was defined as the time from diagnosis to death or last known follow up. OS/DFS estimates were generated using Kaplan-Meier methods and compared using Log-rank tests. Cox proportional hazard models were used to calculate adjusted hazard ratios (aHR) for OS/DFS. RESULTS: A total of 369 patients received trastuzumab therapy; 106 (29%) patients experienced treatment interruption at least once and 42 (11%) permanently discontinued trastuzumab prior to completing planned therapy. TIC was the most common reason for interruption (66 patients, 62%). The median duration of trastuzumab in patients with treatment interruption was 11.3 months (range: 0.5-16.9) with 24 (23%) patients receiving ≤6 months of therapy. This duration includes the time delay related to treatment interruption. Patients with any treatment interruption had worse DFS (aHR: 4.4, p = 0.001) and OS (aHR: 4.8, p < 0.001) after adjusting for age, stage, grade, ER, node status and TIC. CONCLUSIONS: Treatment interruption or early discontinuation of trastuzumab therapy in early HER2-positive BC, most often from TIC, is an independent prognostic marker for worse DFS and OS in operable HER2-positive BC. Future prospective studies should consider targeting at-risk populations and optimizing cardiac function to avoid interruption in trastuzumab therapy.

Features, Outcomes, and Management Strategies of Male Breast Cancer: A Single Institution Comparison to Well-Matched Female Controls.

OBJECTIVE: The primary objective of this study was to delineate differences in management, overall and distant disease-free survival in males diagnosed with breast cancer and treated at The Ohio State University Comprehensive Cancer Center as compared to comprehensively matched female subjects. Secondary objectives included assessment of clinical and histopathologic features and recurrence score, as measured by Oncotype DX and the modified Magee equation #2. MATERIALS AND METHODS: This single institution retrospective study compared male and comprehensively matched female patients (1:2) with stage I-III breast cancer between 1994 and 2014. Recurrence risk was estimated using a modified Magee equation. Overall survival and distant disease-free survival were estimated and compared using Kaplan-Meier and Log-rank methods. RESULTS: Forty-five male breast cancer patients were included (stage I: 26.7%; stage II: 53.3%; stage III: 20.0%; hormone receptor positive: 97.8%; human epidermal growth factor receptor 2 negative: 84.4%) with a median age of 63.8 (43.0-79.4) years at diagnosis. Intermediate and low recurrence scores were most common in male and female patients respectively; mean score was similar between groups (20.3 vs. 19.8). The proportion of male breast cancer patients treated with adjuvant chemotherapy and post-mastectomy radiation was lower compared to female patients (42.2% vs. 65.3%, p=0.013; 22.7% vs. 44.4%, p=0.030, respectively). Overall survival and distant disease-free survival between male and female patients were similar. CONCLUSION: Male breast cancer patient outcomes were similar compared to well-matched female patients suggesting that breast cancer specific factors are more prognostic than gender.

TTF-1 Positive Primary Small Cell Carcinoma of the Breast: A Case Report and Review of the Literature.

Primary small cell carcinoma of the breast (SCCB) is a rare tumor subtype comprising <0.1% of all breast carcinomas. Here we present a case of thyroid transcription factor-1 (TTF-1) positive SCCB that recurred within 3 years of diagnosis in the lung and lymph nodes. Given the small number of cases, no clear guidelines exist on the appropriate management of patients with these aggressive tumors. We present a case study and review the current literature to highlight the knowledge gaps and needs of patients with these rare tumors. A 50-year-old premenopausal woman with no family history, presented with a palpable right breast mass. Biopsy was consistent with primary SCCB that was poorly differentiated, positive for synaptophysin and chromogranin and TTF-1 and presence of ductal carcinoma in situ component showing neuroendocrine differentiation. Imaging with PET, CT, and MRI brain excluded any other sites of primary disease. She underwent a right lumpectomy with axillary lymph node dissection and was treated with adjuvant cisplatin-based chemotherapy and concurrent radiation therapy. Thirty-four months later, routine scans showed a new right lower-lobe lung nodule and an enlarged sub-carinal node that was proven to be poorly differentiated neuroendocrine cancer. This case report sheds light on a rarely described disease and provides a comprehensive approach to diagnosis and management. Primary SCCB is an extremely rare, aggressive form of breast cancer that is molecularly and histologically similar to SCLC. However, a review of the literature highlights recent mutational analyses that show important differences between these two cancer types, including an increase in PIK3CA mutations in primary SCCB. Further studies, including genomic analyses are needed to better define this malignancy and to develop a standard treatment.

Iron trafficking inside the brain.

Iron, an essential element for all cells of the body, including those of the brain, is transported bound to transferrin in the blood and the general extracellular fluid of the body. The demonstration of transferrin receptors on brain capillary endothelial cells (BCECs) more than 20 years ago provided the evidence for the now accepted view that the first step in blood to brain transport of iron is receptor-mediated endocytosis of transferrin. Subsequent steps are less clear. However, recent investigations which form the basis of this review have shed some light on them and also indicate possible fruitful avenues for future research. They provide new evidence on how iron is released from transferrin on the abluminal surface of BCECs, including the role of astrocytes in this process, how iron is transported in brain extracellular fluid, and how iron is taken up by neurons and glial cells. We propose that the divalent metal transporter 1 is not involved in iron transport through the BCECs. Instead, iron is probably released from transferrin on the abluminal surface of these cells by the action of citrate and ATP that are released by astrocytes, which form a very close relationship with BCECs. Complexes of iron with citrate and ATP can then circulate in brain extracellular fluid and may be taken up in these low-molecular weight forms by all types of brain cells or be bound by transferrin and taken up by cells which express transferrin receptors. Some iron most likely also circulates bound to transferrin, as neurons contain both transferrin receptors and divalent metal transporter 1 and can take up transferrin-bound iron. The most likely source for transferrin in the brain interstitium derives from diffusion from the ventricles. Neurons express the iron exporting carrier, ferroportin, which probably allows them to excrete unneeded iron. Astrocytes lack transferrin receptors. Their source of iron is probably that released from transferrin on the abluminal surface of BCECs. They probably to export iron by a mechanism involving a membrane-bound form of the ferroxidase, ceruloplasmin. Oligodendrocytes also lack transferrin receptors. They probably take up non-transferrin bound iron that gets incorporated in newly synthesized transferrin, which may play an important role for intracellular iron transport.

The transferrin homologue, melanotransferrin (p97), is rapidly catabolized by the liver of the rat and does not effectively donate iron to the brain.

Melanotransferrin (MTf) or melanoma tumor antigen p97 is a membrane-bound transferrin (Tf) homologue that binds iron (Fe). This protein is also found as a soluble form in the plasma (sMTf) and was suggested to be an Alzheimer's disease marker. In addition, sMTf has been recently suggested to cross the blood-brain barrier (BBB) and accumulate in the brain of the mouse following intravenous infusion. Considering the importance of this observation to the physiology and pathophysiology of the BBB and the function of sMTf in vivo, we investigated the uptake and distribution of 59Fe-125I-sMTf and compared it to 59Fe-125I-Tf that were injected intravenously in rats. Studies were also performed to measure 59Fe and 125I-protein uptake by reticulocytes using these radiolabelled proteins. The results showed that sMTf was rapidly catabolized, mainly in the liver and to a lesser extent by the kidneys. The 59Fe was largely retained by these organs but the 125I was released into the plasma. Only a small amount of 125I-sMTf or its bound 59Fe was taken up by the brain, less than that from 59Fe-125I-Tf. There was much less 59Fe uptake by erythropoietic organs (spleen and femurs) from 59Fe-sMTf than from 59Fe-Tf, and no evidence of receptor-mediated uptake of sMTf was obtained using reticulocytes. It is concluded that compared to Tf, sMTf plays little or no role in Fe supply to the brain and erythropoietic tissue. However, a small amount of sMTf was taken up from the plasma by the brain and a far greater amount by the liver.

Iron and magnesium exchange via the low affinity iron transporter in rabbit erythroid cells-exchange rates and the action of valinomycin, diethylstilbestrol and protein kinase inhibitors.

Evidence was presented previously that rabbit erythroid cells possess a low-affinity Fe2+ transport system which operates via the Na+/Mg2+antiport [Biochim. Biophys. Acta 1282 (1996) 163]. This was investigated further by measurements of Mg2+ efflux as well as Fe2+ uptake by the cells and by examining the inhibitory effects of valinomycin, diethylstilbestrol (DES) and protein kinase inhibitors. Mg2+ efflux and Fe2+ uptake were measured using rabbit reticulocytes and mature erythrocytes incubated in isotonic KCl or NaCl solutions. Both processes were slower in mature cells than reticulocytes. Mg2+ efflux into KCl solution was much lower than into NaCl solution but was stimulated by addition of Fe2+ to the solution. The rate of Fe2+-stimulated Mg2+ efflux closely followed that of Fe2+ uptake in a one-to-one molar ratio. Valinomycin, DES and the protein kinase inhibitors all inhibited Fe2+ uptake from KCl solution. Valinomycin also inhibited Fe2+-stimulated Mg2+ efflux into KCl solution but markedly stimulated the efflux into NaCl. Maximal inhibition of Fe2+ uptake from KCl solution required the presence of K+, Rb+ or Cs+ ions with which valinomycin forms strong complexes. The results could not be explained on the basis of changes in cell membrane potential or cell volume. By contrast, the increase in Mg2+ efflux into NaCl solution produced by valinomycin was accompanied by cell shrinkage and production of a more negative membrane potential, either of which may be responsible for the effect. The inhibition produced by the protein kinase inhibitors indicate that phosphorylation of the transporter or an associated protein by protein tyrosine kinase is probably required to activate the transporter.

Iron and transition metal transport into erythrocytes mediated by nifedipine degradation products and related compounds.

The aim of this investigation was to determine the mechanism of action of the nitrosophenylpyridine derivative of nifedipine ("nitrosonifedipine", NN) on Fe(II) transport into erythrocytes. Nifedipine is rapidly degraded to NN by daylight. We used rabbit erythrocytes, NN, and several chemically related substances, and examined their effects on the transfer of iron and other transition metals (cadmium, cobalt, manganese, nickel, zinc) into and out of the cells. NN mediated the transfer of iron and zinc but not the other metals into the cell cytosol. The transfer of Fe(II) was not affected by changes in cell membrane potential and could not be ascribed to free radical production. Two hydroxamic acid compounds chemically related to NN also stimulated iron and zinc uptake, but no evidence was obtained for cell-induced transformation of NN to them. In vivo, NN is probably converted to a lactam derivative. This compound was found to have no effect on iron uptake by the cells. It is concluded that NN has a relatively high specificity for the transport of iron compared with other transition metals, and small changes in its structure markedly affect this action. Also, because the lactam to which NN is converted in vivo is inactive, it is unlikely that nifedipine will affect iron metabolism after therapeutic administration.

The metabolism of neuronal iron and its pathogenic role in neurological disease: review.

Neurons need iron, which is reflected in their expression of the transferrin receptor. The concurrent expression of the ferrous iron transporter, divalent metal transporter I (DMT1), in neurons suggests that the internalization of transferrin is followed by detachment of iron within recycling endosomes and transport into the cytosol via DMT1. To enable DMT1-mediated export of iron from the endosome to the cytosol, ferric iron must be reduced to its ferrous form, which could be mediated by a ferric reductase. The presence of nontransferrin-bound iron in brain extracellular fluids suggests that neurons can also take up iron in a transferrin-free form. Neurons are thought to be devoid of ferritin in many brain regions in which there is an association between iron accumulation and cellular damage, for example, neurons of the substantia nigra pars compacta. The general lack of ferritin together with the prevailing expression of the transferrin receptor indicates that iron acquired by activity of transferrin receptors is directed toward immediate use in relevant metabolic processes, is exported, or is incorporated into complexes other than ferritin. Iron has long been considered to play a significant role in exacerbating degradation processes in brain tissue subjected to acute damage and neurodegenerative disorders. In brain ischemia, the damaging role of iron may depend on the inhibition of detoxifying enzymes responsible for catalyzing the oxidation of ferrous iron. Brain ischemia may also lead to an increase in iron supply to neurons as transferrin receptor expression by brain capillary endothelial cells is increased. Pharmacological blockage of the transferrin receptor/DMT1-mediated uptake could be a target to prevent further iron uptake. In chronic neurodegenerative settings, a deleterious role of iron is suggested since cases of Alzheimer's disease, Parkinson's disease, and Huntington's disease have a significantly higher accumulation of iron in affected regions. Dopaminergic neurons are rich in neuromelanin, shown to be more redox-active in Parkinson's disease cases. Iron-containing inflammatory cells may, however, account for the main portion of iron present in neurodegenerative disorders. More knowledge about iron metabolism in normal and diseased neurons is warranted as this may identify pharmaceutical targets to improve neuronal iron management.