The East Africa Consortium for human papillomavirus and cervical cancer in women living with HIV/AIDS

The East Africa Consortium was formed to study the epidemiology of human papillomavirus (HPV) infections and cervical cancer and the influence of human immunodeficiency virus (HIV) infection on HPV and cervical cancer, and to encourage collaborations between researchers in North America and East African countries. To date, studies have led to a better understanding of the influence of HIV infection on the detection and persistence of oncogenic HPV, the effects of dietary aflatoxin on the persistence of HPV, the benefits of antiretroviral therapy on HPV persistence, and the differences in HPV detections among HIV-infected and HIV-uninfected women undergoing treatment for cervical dysplasia by either cryotherapy or LEEP. It will now be determined how HPV testing fits into cervical cancer screening programs in Kenya and Uganda, how aflatoxin influences immunological control of HIV, how HPV alters certain genes involved in the growth of tumours in HIV-infected women. Although there have been challenges in performing this research, with time, this work should help to reduce the burden of cervical cancer and other cancers related to HIV infection in people living in sub-Saharan Africa, as well as optimized processes to better facilitate research as well as patient autonomy and safety. KEY MESSAGESThe East Africa Consortium was formed to study the epidemiology of human papillomavirus (HPV) infections and cervical cancer and the influence of human immunodeficiency virus (HIV) infection on HPV and cervical cancer.Collaborations have been established between researchers in North America and East African countries for these studies.Studies have led to a better understanding of the influence of HIV infection on the detection and persistence of oncogenic HPV, the effects of dietary aflatoxin on HPV detection, the benefits of antiretroviral therapy on HPV persistence, and the differences in HPV detections among HIV-infected and HIV-uninfected women undergoing treatment for cervical dysplasia by either cryotherapy or LEEP.

Investigating a key structural determinant of health, racism, and related social determinants of health in Massachusetts during the COVID-19 pandemic

A disproportionate burden of the ongoing COVID-19 pandemic is being shouldered by members of racial and ethnic minorities and socially disadvantaged communities. Structural and social determinants of health have been recognized as key contributors to the inequalities observed. Racism, a major structural determinant of health that patterns related social determinants of health, in the USA, warrants further investigation. In this perspective piece we provide an overview of the historical context of racism, followed by preliminary findings from the ongoing COVIDStory study-a cross-sectional study addressing perceptions of COVID-19 and COVID-19 research-that highlights the experiences of non-Hispanic Black and Hispanic identifying adult participants, residing in Worcester Massachusetts, during the COVID-19 pandemic. We then discuss these findings in the context of current and past research considering racism and relevant social determinants of health. Our study results suggest that racism and its residuals (residential segregation, economic insecurity, discrimination, bias, and vigilance) are modern challenges for non-Hispanic Black and Hispanic participants, and these findings are supported by the existing literature. It is our hope that this perspective piece provides additional evidence for action on structural and social determinants affecting the health of minoritized people, especially those living in Massachusetts.

Oropharyngeal microbiome profiled at admission is predictive of the need for respiratory support among COVID-19 patients

The oropharyngeal microbiome, the collective genomes of the community of microorganisms that colonizes the upper respiratory tract, is thought to influence the clinical course of infection by respiratory viruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Infectious Disease 2019 (COVID-19). In this study, we examined the oropharyngeal microbiome of suspected COVID-19 patients presenting to the Emergency Department and an inpatient COVID-19 unit with symptoms of acute COVID-19. Of 115 initially enrolled patients, 50 had positive molecular testing for COVID-19+ and had symptom duration of 14 days or less. These patients were analyzed further as progression of disease could most likely be attributed to acute COVID-19 and less likely a secondary process. Of these, 38 (76%) went on to require some form of supplemental oxygen support. To identify functional patterns associated with respiratory illness requiring respiratory support, we applied an interpretable random forest classification machine learning pipeline to shotgun metagenomic sequencing data and select clinical covariates. When combined with clinical factors, both species and metabolic pathways abundance-based models were found to be highly predictive of the need for respiratory support (F1-score 0.857 for microbes and 0.821 for functional pathways). To determine biologically meaningful and highly predictive signals in the microbiome, we applied the Stable and Interpretable RUle Set to the output of the models. This analysis revealed that low abundance of two commensal organisms, Prevotella salivae or Veillonella infantium (< 4.2 and 1.7% respectively), and a low abundance of a pathway associated with LPS biosynthesis (< 0.1%) were highly predictive of developing the need for acute respiratory support (82 and 91.4% respectively). These findings suggest that the composition of the oropharyngeal microbiome in COVID-19 patients may play a role in determining who will suffer from severe disease manifestations.

Oropharyngeal Microbiome Profiled at Admission is Predictive of the Need for Respiratory Support Among COVID-19 Patients

The clinical course of infection due to respiratory viruses such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2), the causative agent of Coronavirus Disease 2019 (COVID-19) is thought to be influenced by the community of organisms that colonizes the upper respiratory tract, the oropharyngeal microbiome. In this study, we examined the oropharyngeal microbiome of suspected COVID-19 patients presenting to the Emergency Department and an inpatient COVID-19 unit with symptoms of acute COVID-19. Of 115 enrolled patients, 74 were confirmed COVID-19+ and 50 had symptom duration of 14 days or less; 38 acute COVID-19+ patients (76%) went on to require respiratory support. Although no microbiome features were found to be significantly different between COVID-19+ and COVID-19-patients, when we conducted random forest classification modeling (RFC) to predict the need of respiratory support for the COVID-19+ patients our analysis identified a subset of organisms and metabolic pathways whose relative abundance, when combined with clinical factors (such as age and Body Mass Index), was highly predictive of the need for respiratory support (F1 score 0.857). Microbiome Multivariable Association with Linear Models (MaAsLin2) analysis was then applied to the features identified as predicative of the need for respiratory support by the RFC. This analysis revealed reduced abundance of Prevotella salivae and metabolic pathways associated with lipopolysaccharide and mycolic acid biosynthesis to be the strongest predictors of patients requiring respiratory support. These findings suggest that composition of the oropharyngeal microbiome in COVID-19 may play a role in determining who will suffer from severe disease manifestations.

Importance

The microbial community that colonizes the upper airway, the oropharyngeal microbiome, has the potential to affect how patients respond to respiratory viruses such as SARS-CoV2, the causative agent of COVID-19. In this study, we investigated the oropharyngeal microbiome of COVID-19 patients using high throughput DNA sequencing performed on oral swabs. We combined patient characteristics available at intake such as medical comorbidities and age, with measured abundance of bacterial species and metabolic pathways and then trained a machine learning model to determine what features are predicative of patients needing respiratory support in the form of supplemental oxygen or mechanical ventilation. We found that decreased abundance of some bacterial species and increased abundance of pathways associated bacterial products biosynthesis was highly predictive of needing respiratory support. This suggests that the oropharyngeal microbiome affects disease course in COVID-19 and could be targeted for diagnostic purposes to determine who may need oxygen, or therapeutic purposes such as probiotics to prevent severe COVID-19 disease manifestations.

Detection of types of HPV among HIV-infected and HIV-uninfected Kenyan women undergoing cryotherapy or loop electrosurgical excision procedure

OBJECTIVE

To assess the baseline types of HPV infection among HIV-positive and HIV-negative women in western Kenya undergoing cryotherapy or loop electrosurgical excision procedure (LEEP) for cervical intraepithelial neoplasia.

METHODS

A prospective observational study was conducted of baseline HPV characteristics of women undergoing visual inspection with acetic acid (VIA) and cryotherapy or LEEP. After a positive VIA in HIV-positive and HIV-negative women, data on demographics, CD4 count, and use of antiretroviral therapy and a cervical swab were collected. HPV typing was performed using the Roche Linear Array.

RESULTS

Of 175 participants, 86 (49.1%) were HIV-positive and had a higher prevalence of low-risk HPV types (odds ratio [OR] 5.28, P=0.005) compared with HIV-negative women. The most common high-risk (HR)-HPV types in HIV-positive women were HPV 16 (13.9%) and HPV 18 (11.1%). HIV-positive women requiring LEEP were more likely to have HR-HPV types (OR 6.67, P=0.012) and to be infected with multiple HR-HPV types (OR 7.79, P=0.024) compared to those undergoing cryotherapy.

CONCLUSION

HIV-positive women requiring LEEP versus cryotherapy had a higher prevalence of any HR-HPV type and multiple HR-HPV types. There were no such differences in HPV types identified among HIV-negative women.

Abstract A18: Characterization of checkpoint inhibitors in the tumor microenvironment (TME) and peripheral blood in endemic Burkitt Lymphoma

Introduction: The tumor microenvironment and the interaction between immune checkpoint inhibitors (ICIs) and tumor cells are essential to understand for designing future immunotherapy strategies. In this study, we aim to characterize the tumor microenvironment (TME) in children diagnosed with endemic Burkitt lymphoma (eBL), the most common pediatric cancer in Africa. A history of chronic malaria (Plasmodium falciparum) and Epstein-Barr virus (EBV) coinfections are both risk factors in the etiology of eBL.

Methods: Using multicolor flow cytometry and single-cell RNA sequencing, we analyzed the expression of immune checkpoint inhibitors in T cells from the tumor microenvironment and from peripheral blood mononuclear cells (PBMC) of eBL patients, along with age-matched controls with different malaria exposure. Additionally, CD8 T-cell infiltration was confirmed by immunohistochemistry.

Results: PD-1+ CD4 T cells from eBL PBMCs were increased in number compared to healthy controls from the malaria-endemic area (p=0.03). Both CD4 and CD8 T cells from eBL PBMCs reveal higher frequency of TIGIT expressers compared to healthy controls (non-malaria endemic) (p=0.002, p=0.007 respectively). PD1+ TIGIT+ IFNG- memory CD4 T cells phenotype from eBL PBMCs was increased upon short stimulation with PMA/ionomycin, as well as “naive-like” CD95+ PD1high TIGIT+ CTLA4+ IFNG+ CD8T cells. Tumor samples from 4 eBL patient were used on single-cell analysis; we observed activated T-cells profile that highly upregulated TIGIT within the tumor microenvironment. We also noticed relatively low expression of other ICIs such as PD1, TIM3, LAG3, and CTLA4. Base on all these data, we calculated an exhaustion score that was higher than the cytotoxicity score in our eBL-derived tumor-infiltrating lymphocytes (TILs). In addition, we use immunohistochemistry staining to confirm CD8 T-cell infiltration and ICI expression in eBL tumor fine needle aspirates. Our future directions will employ TIGIT blockade inhibitor studies of CD8 T cells, in order to increase expansion and function of CD8 TILs. Our results will help support future development of ICI therapies in endemic Burkitt lymphoma.

Citation Format: Priya Saikumar-Lakshmi, Cliff Oduor, Catherine Forconi, Patrick Marsh, John Michael Ong’echa, Jeffrey Bailey, Ann Moormann. Characterization of checkpoint inhibitors in the tumor microenvironment (TME) and peripheral blood in endemic Burkitt Lymphoma [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr A18.

Endemic Burkitt lymphoma - an aggressive childhood cancer linked to Plasmodium falciparum exposure, but not to exposure to other malaria parasites

Burkitt lymphoma (BL) is an aggressive non-Hodgkin lymphoma. The prevalence of BL is ten-fold higher in areas with stable transmission of Plasmodium falciparum malaria, where it is the most common childhood cancer, and is referred to as endemic BL (eBL). In addition to its association with exposure to P. falciparum infection, eBL is strongly associated with Epstein-Barr virus (EBV) infection (>90%). This is in contrast to BL as it occurs outside P. falciparum-endemic areas (sporadic BL), where only a minority of the tumours are EBV-positive. Although the striking geographical overlap in the distribution of eBL and P. falciparum was noted shortly after the first detailed description of eBL in 1958, the molecular details of the interaction between malaria and eBL remain unresolved. It is furthermore unexplained why exposure to P. falciparum appears to be essentially a prerequisite to the development of eBL, whereas other types of malaria parasites that infect humans have no impact. In this brief review, we summarize how malaria exposure may precipitate the malignant transformation of a B-cell clone that leads to eBL, and propose an explanation for why P. falciparum uniquely has this capacity.

Presentation and Treatment Outcomes of Liberian Children Age 5 Years and Under Diagnosed With Severe Malaria

Malaria is endemic in Liberia with a prevalence rate of up to 60% in some regions, and it has been a major cause of death in children under 5 years of age. Prior to the recent Ebola epidemic, we undertook a prospective, hospital-based pilot study at the National Referral Hospital in Monrovia, to characterize the presentation, accuracy of diagnosis, and treatment outcomes of children presenting for treatment of malaria. From June 2013 to May 2014, we recruited children 5 years and under who presented to the JFK Medical Center with suspected malaria. We collected both clinical and laboratory data on admission and on discharge. We enrolled 477 patients with an average age of 1.6 years. Demographic factors associated with testing negative for malaria included regular bed net use and prior treatment for malaria. The most common presenting symptoms of severe malaria in this population were headache and seizures. Of 246 patients admitted and treated for severe malaria, 33% tested negative by rapid diagnostic test and blood smear for malaria. The case fatality rate was higher for the patients who tested negative for malaria (4.9%) versus those who tested positive (0.6%). Three children who tested negative for malaria showed evidence of undiagnosed Salmonella typhi infection. These results suggest that malaria may be overdiagnosed and that the diagnoses of other infectious diseases, which present in a similar fashion, may be neglected. These findings underscore the need to develop rapid diagnostic tests to screen for alternative causes of febrile illness.

Comparison of HPV detection in HIV-infected and HIV-uninfected Kenyan women with or without cervical dysplasia

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Background: Cervical cancer, a malignancy caused by human papillomavirus (HPV) infection, is the most common malignancy in women living in sub-Saharan African countries including Kenya. HIV co-infection accelerates the natural course of cervical cancer. To determine the specific HPV type distribution in HIV-infected women compared to HIV-uninfected women, with and without evidence of cervical dysplasia. Methods: Demographic information, behavioral data, and a cervical swab were collected from women 18 and 45 years of age, HIV-infected or HIV-uninfected, who presented for cervical cancer screening at Moi Referral and Teaching Hospital in Eldoret, Kenya. Women were triaged based on the presence or absence of cervical dysplasia. HPV testing was performed using the Roche Linear Array Assay. Results were compared between women with or without HIV co-infection and between those with or without cervical dysplasia, using Chi-square tests or Fisher’s exact tests. Results: 223 women had normal VIAs. All had HPV testing, 221 had valid results: 115 HIV-infected women (mean age 37 years) and 106 HIV-uninfected (mean age 33 years). 175 women had abnormal VIAs. 143 women had HPV testing performed, 140 had valid results: 70 HIV-infected women (mean age 38.5 years) and 70 HIV-uninfected (mean age 31.3 years). Greater than 90% of all HIV-infected women in both projects were receiving anti-retroviral therapy at enrollment. HPV of any type was detected in 48% of all women with normal VIA vs. 61% of women with abnormal VIA (P = 0.018). High risk (HR)-HPV was detected in 38% of all women with normal VIA vs. 51% of all women with abnormal VIA (P = 0.012). HIV-uninfected women with normal VIA had significantly lower detection of all HPV (P = 0.026), high risk-HPV (P = 0.018), IARC high risk-HPV (P = 0.047), A9 types (P = 0.050), and individual types HPV 16 (P = 0.0274), HPV 18 (P = 0.007), and HPV 51 (P = 0.009) than HIV-uninfected women with abnormal VIA. Among HIV-infected women, there was no difference in detection of any group of HPV types or individual types with respect to VIA results. Conclusions: HIV-uninfected women without cervical dysplasia had lower detection of oncogenic HPV than HIV-uninfected women with dysplasia. In contrast, HPV detection did not differ among HIV-infected women between those with or without cervical dysplasia. In addition, VIA appears to lack specificity for HPV-associated cervical dysplasia, as 39% of women with abnormal VIA examinations did not have any HPV detected, and 49% of women with abnormal VIA examinations did not have any HR-HPV detected.

A phase II trial testing interventions to shorten time to diagnosis and reduce abandonment of treatment of children with Burkitt lymphoma in Kenya

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Background: Burkitt Lymphoma (BL) is a common pediatric cancer in sub-Saharan Africa. Despite advances in care, prognosis is poor. The BL treatment protocol at our center in Kenya used since 2010, had a one-year survival of 29% (Martijn et al. BMJ Paed Open 2017). We hypothesized that financial burdens and delays in start of therapy impact outcomes. Methods: Our trial tested interventions aimed to: 1) Shorten time from presentation to start of treatment to improve survival; and 2) Support families during therapy to reduce abandonment. Initial eligibility included clinical suspicion of BL in a child 0-13 years of age. Patients with confirmed diagnosis of a mature B-cell lymphoma received support to complete therapy. Children with prior treatment of cancer were excluded. The trial was approved by human protection boards in Kenya and Indiana and consent was obtained prior to study entry. We enrolled 96 children with possible BL. Study personnel expedited routing of tissue samples to laboratories. Touch preps or smears were stained with Giemsa and reviewed by pathologists. Fresh tissue from all sources was used for flow cytometry. Tissue from core needle or incisional biopsies was processed for routine and immunohistochemical staining. Of 96 patients, 43 had BL confirmed by pathologic studies and were treated with combination chemotherapy given over 25 weeks. We paid families for transport costs for care, called after missed appointments, and provided direct monetary support (~$200 USD) for the 200 days children were on treatment. Results: Facilitating the biopsy shortened, by 3 days, the median time from admission to initiation of therapy for BL, because families did not need to raise funds for testing. Monetary support reduced abandonment of treatment by patients. Only 2 of 43 (5%) patients abandoned therapy, compared to abandonment by 22 of a cohort of 63 (35%) patients treated previously (p < 0.001). The combination of rapid diagnosis, early therapy, and financial support and communication with families improved event free survival of children with BL to 50% at 1 year (p = 0.045). Conclusions: Simple interventions to improve efficiency of diagnosis and reduce abandonment leads to improved outcomes for children with BL in Kenya.

A cross-sectional analysis of factors associated with detection of oncogenic human papillomavirus in human immunodeficiency virus-infected and uninfected Kenyan women

Background

Cervical cancer is caused by oncogenic human papillomaviruses (HPV) and is one of the most common malignancies in women living in sub-Saharan Africa. Women infected with the human immunodeficiency virus (HIV) have a higher incidence of cervical cancer, but the full impact on HPV detection is not well understood, and associations of biological and behavioral factors with oncogenic HPV detection have not been fully examined. Therefore, a study was initiated to investigate factors that are associated with oncogenic HPV detection in Kenyan women.

Methods

Women without cervical dysplasia were enrolled in a longitudinal study. Data from enrollment are presented as a cross-sectional analysis. Demographic and behavioral data was collected, and HPV typing was performed on cervical swabs. HIV-uninfected women (n = 105) and HIV-infected women (n = 115) were compared for demographic and behavioral characteristics using t-tests, Chi-square tests, Wilcoxon sum rank tests or Fisher’s exact tests, and for HPV detection using logistic regression or negative binomial models adjusted for demographic and behavioral characteristics using SAS 9.4 software.

Results

Compared to HIV-uninfected women, HIV-infected women were older, had more lifetime sexual partners, were less likely to be married, were more likely to regularly use condoms, and were more likely to have detection of HPV 16, other oncogenic HPV types, and multiple oncogenic types. In addition to HIV, more lifetime sexual partners was associated with a higher number of oncogenic HPV types (aIRR 1.007, 95% CI 1.007–1.012). Greater travel distance to the clinic was associated with increased HPV detection (aOR for detection of ≥ 2 HPV types: 3.212, 95% CI 1.206–8.552). Older age (aOR for HPV 16 detection: 0.871, 95% CI 0.764–0.993) and more lifetime pregnancies (aOR for detection of oncogenic HPV types: 0.706, 95% CI, 0.565–0.883) were associated with reduced detection.

Conclusion

HIV infection, more lifetime sexual partners, and greater distance to health-care were associated with a higher risk of oncogenic HPV detection, in spite of ART use in those who were HIV-infected. Counseling of women about sexual practices, improved access to health-care facilities, and vaccination against HPV are all potentially important in reducing oncogenic HPV infections.

New gorilla adenovirus vaccine vectors induce potent immune responses and protection in a mouse malaria model

Background

A DNA-human Ad5 (HuAd5) prime-boost malaria vaccine has been shown to protect volunteers against a controlled human malaria infection. The potency of this vaccine, however, appeared to be affected by the presence of pre-existing immunity against the HuAd5 vector. Since HuAd5 seroprevalence is very high in malaria-endemic areas of the world, HuAd5 may not be the most appropriate malaria vaccine vector. This report describes the evaluation of the seroprevalence, immunogenicity and efficacy of three newly identified gorilla adenoviruses, GC44, GC45 and GC46, as potential malaria vaccine vectors.

Results

The seroprevalence of GC44, GC45 and GC46 is very low, and the three vectors are not efficiently neutralized by human sera from Kenya and Ghana, two countries where malaria is endemic. In mice, a single administration of GC44, GC45 and GC46 vectors expressing a murine malaria gene, Plasmodium yoelii circumsporozoite protein (PyCSP), induced robust PyCSP-specific T cell and antibody responses that were at least as high as a comparable HuAd5-PyCSP vector. Efficacy studies in a murine malaria model indicated that a prime-boost regimen with DNA-PyCSP and GC-PyCSP vectors can protect mice against a malaria challenge. Moreover, these studies indicated that a DNA-GC46-PyCSP vaccine regimen was significantly more efficacious than a DNA-HuAd5-PyCSP regimen.

Conclusion

These data suggest that these gorilla-based adenovectors have key performance characteristics for an effective malaria vaccine. The superior performance of GC46 over HuAd5 highlights its potential for clinical development.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-1911-z) contains supplementary material, which is available to authorized users.

Mentoring future Kenyan oncology researchers

This is a summary of the 1^st Academic Model Providing Access to Healthcare (AMPATH) Oncology Institute research grant writing workshop organized in collaboration with the Kenya Medical Research Institute (KEMRI) and held in Kisumu, Kenya from January 16^th to 18^th, 2013. The goal of this meeting was to mentor future Kenyan scientists and prioritize research topics that would lead to improved cancer care and survival for the citizens of Kenya.

EBNA-1 specific effector T cell deletion associated with holoendemic malaria exposure in the etiology of endemic Burkitt’s lymphoma (P3063)

Etiological mechanism of eBL remain largely unknown despite long-standing epidemiological link between malaria and EBV co-infection. Age-dependent deficiency in EBV-specific CD8+ T cell-mediated IFN-γ immunosurveillance has been reported in malaria holoendemic exposed children which has been associated with eBL diagnosis. We sought to investigate whether qualitative differences in EBNA-1 specific T cells existed in malaria-exposed children to explain their increased risk for eBL. We conducted a cross-sectional study of healthy children from western Kenya with divergent malaria exposure:Kisumu (holoendemic) and Nandi (hypoendemic) and eBL age-matched patients. T cell effector function was evaluated by multiparameter flow cytometry against T cell lineage markers(CD3,4,8,45RA & CCR7) and functional phenotype (IFN-γ, IL10, IL17 & PD1) to EBNA-1. EBNA-1 specific responses were compared to MSP-1, EBNA2 and EBNA3A. We found significantly higher IFN-γ responses to MSP1 in the eBL & Kisumu compared to Nandi children (p=0.03), in contrast to EBNA1, which were significantly lower in eBL and Kisumu compared to Nandi children (p=0.01). Responses to EBNA2 and EBNA3A did not differ between groups. IFN-γ was generated from CD4 TEM and a heterogeneous combination of CD8 T-cells. PD-1 expressing T-cells were less frequent in eBL patients and highest in Kisumu children.This suggests that the EBNA1-specific deficiencies are due to deletion of T-cell population due to malaria induced exhaustion.

Immune escape by Epstein-Barr virus associated malignancies

Persistent Epstein-Barr virus (EBV) infection remains asymptomatic in the majority of virus carriers, despite the potent growth transforming potential of this virus. The increased frequency of EBV associated B cell lymphomas in immune compromised individuals suggests that tumor-free chronic infection with this virus is in part due to immune control. Here we discuss the evidence that loss of selective components of EBV specific immunity might contribute to EBV associated malignancies, like nasopharyngeal carcinoma, Burkitt's and Hodgkin's lymphoma, in otherwise immune competent patients. Furthermore, we discuss how current vaccine approaches against EBV might be able to target these selective deficiencies.

Strategies to overcome myelotoxic therapy for the treatment of Burkitt's and AIDS-related non-Hodgkin's lymphoma

BACKGROUND

Strategies to circumvent or lessen the myelotoxicity associated with combination chemotherapy may improve the overall outcome of the management of patients particularly in resource poor settings.

OBJECTIVES

To develop effective non-myelotoxic therapies for Burkitt's Lymphoma (BL) and AIDS-related non-Hodgkin's lymphoma.

DATA SOURCES

Publications, original and review articles, conference abstracts searched mainly on Pubmed indexed for medline.

DATA EXTRACTION

A systematic review of the clinical problem of combination chemotherapy. Identification of clinical strategies that circumvent or lessen the myelotoxicity of combination cytotoxic chemotherapy. Length of survival, lack of clinically significant (> grade 3) myelosuppression and weight loss were used as markers of myelotoxicity.

DATA SYNTHESIS

Review of published experience with some of these strategies including dose-modification of multi-agent chemotherapy; rationale for targeted therapies, and the preclinical development of a mouse model exploring the role of metronomic scheduling substantiate pragmatism and feasibility of these approaches.

CONCLUSION

Myelotoxic death rates using multi-agent induction chemotherapy approach 25% for endemic Burkitt's lymphoma and range between 20% to 60% for AIDS-related malignancy. This is mostly explained by the paucity of supportive care compounded by wasting and inanition attributable to advanced cancer and HIV infection making patients more susceptible to myelosuppressive side effects of cytotoxic chemotherapy. Investigations and alternative approaches that lessen or circumvent myelotoxicity of traditional cytotoxic chemotherapy for the management of Burkitt's lymphoma and AIDS-related non-Hodgkin's lymphoma in the resource-constrained setting are warranted. Pertinent pre-clinical and clinical data are emerging to support the need for abrograting the myelosuppressive effects of traditional cytotoxic chemotherapy. This can be achieved by developing targeted anti-viral and other strategies, such as the use of bryostatin 1 and vincristine, and by developing a preclinical mouse model to frame the clinical rationale for a pilot trial of metronomic therapy for the treatment of Burkitt's and AIDS-related lymphoma. Implementation of these investigational approaches must be encouraged as viable anti-cancer therapeutic strategies particularly in the resource-constrained settings.

Activation of the Epstein-Barr virus lytic cycle by the latex of the plant Euphorbia tirucalli

Exposure to the plant Euphorbia tirucalli has been proposed to be a cofactor in the genesis of endemic Burkitt's lymphoma (eBL). The purpose of this study was to examine the effects of unpurified E. tirucalli latex on Epstein-Barr virus (EBV) gene expression. A Burkitt lymphoma cell line was treated with varying dilutions of the latex and the effects on EBV gene expression were measured. We observed that the latex was capable of reactivating the EBV lytic cycle in a dose-dependent manner and at dilutions as low as 10(-6). Simultaneous treatment of cells with E. tirucalli latex and the protein kinase C inhibitor 1-(5-isoquinolinesulphonyl)-2-methylpiperazine dihydrochloride blocked lytic cycle activation. These data suggest that environmental exposure to the latex of E. tirucalli could directly activate the EBV lytic cycle and provide further evidence of a role for E. tirucalli in the aetiology of eBL.

Activity of titanocene dihalides against a human colon carcinoma heterotransplanted to athymic mice

The antitumor activity of cis-diamminedichloroplatinum (II) and of two metallocene derivatives, titanocene dichloride (C5H5)2TiCl2 and titanocene dibromide (C5H5)2TiBr2, was investigated against a human colon adenocarcinoma heterotransplanted to athymic mice. The substances were administered at various doses on a Q2DX5 or a Q3DX5 schedule. Whereas cis-diamminedichloroplatinum (II) induced an only marginal tumor-inhibiting effect, both titanocenes markedly suppressed tumor development (T/C values: 23-40%) and caused stagnation and relative decrease of tumor growth, when they were applied in subtoxic doses far below the LD10 level. The results are remarkable with respect to the general insensitivity of human colorectal carcinomas to cytostatic agents.