Abstract: The impact of KRAS mutations on the efficacy of therapies that target the epidermal growth factor receptor (EGFR) is a major, ongoing area of oncology research, aimed at identifying the best possible treatments for individual colon cancer patients. Because patients with KRAS mutant colorectal tumors rarely respond to anti-EGFR monoclonal antibodies, testing is required to confirm the patient's tumor is KRAS wild-type before utilizing these therapies. Despite being studied for more than 30 years, new information continues to develop regarding KRAS and its role in colon carcinogenesis. This information must be integrated into the development of effective colon cancer treatment strategies. This review will summarize recent evidence that most, if not all, colon tumors encompass at least a subpopulation of KRAS mutant cells, meaning tumors characterized as KRAS wild-type are in most cases tumors with relatively low KRAS mutant tumor cell content. Recent studies support the hypothesis that relapse in advanced colorectal patients treated with EGFR-targeted monoclonal antibody therapy involves the outgrowth of previously undetected KRAS mutant tumor cell populations. Studies investigating the effects of oxidative stress on Ras signaling suggest that the frequent presence of minor KRAS mutant tumor cell populations may be a consequence of hypoxic conditions within tumors, which produce a negative selection against KRAS mutant cells in polyclonal tumors. Thus, the literature and current practices for characterizing tumor KRAS mutation don't accurately reflect the nature of colon tumor KRAS mutation, even though an accurate understanding is critical for identifying the best strategies for intervention. ... Read more

Abstract: The use of targeted oral anticancer medications (OAMs) is becoming increasingly prevalent in cancer care. Approximately 25-30% of the oncology drug pipeline involves oral agents and there are now over 50 OAMs approved by the Food and Drug Administration. This change represents a major shift in management of patients with cancer from directly observed, intermittent intravenous therapy to self-administered, oral chronic therapy. The increased prevalence of OAMs raises the issue of adherence in oncology, including understanding the challenges of adherence to OAMs. This review focuses on studies of adherence for patients taking molecularly targeted OAMs for breast cancer, chronic myelogenous leukemia (CML), gastrointestinal stromal tumors (GIST), non-small cell lung cancer (NSCLC), and renal cell carcinoma (RCC). We then discuss barriers to adherence and studies performed to date testing interventions for improving adherence. Finally, we discuss future areas of investigation needed to define and improve adherence to OAMs in targeted therapy for cancer. ... Read more

Abstract: A promising new era of cancer therapeutics with agents that inhibit specific growth stimulatory pathways is finding a new niche in our armamentarium in the war against cancer. Targeted cancer therapeutics, including humanized monoclonal antibodies (mAbs) and tyrosine kinase inhibitors (TKIs), are amongst the major treatment options for cancer today together with cytotoxic chemotherapies. Targeted therapies are more selective for cancer cells and improve the quality of life for cancer patients undergoing treatment. Many of these drugs have been approved by the FDA, and several more are being studied in clinical trials. Although development of targeted therapeutics has improved cancer treatment significantly, the harsh reality is that the "War on Cancer" still exists. Major challenges still exist with the currently marketed inhibitors, including limitations associated with mAbs and TKIs drug types, acquired mechanisms of drug resistance that cause patient relapse, and tumor heterogeneity. Today, there is an urgent need for the development of novel anti-tumor agents that are cheaper, stable, can selectively target cancer dependent pathways without affecting normal cells, and most importantly, avoid development of resistance mechanisms. Peptide mimics have the potential benefits of being highly selective, stable, cheap, and non-toxic. The focus of this review is to discuss the disadvantages associated with the use of monoclonal antibodies and tyrosine kinase inhibitors. A special emphasis will be placed on efforts taken in our laboratory to 1) design peptide vaccines and therapeutics that target cancer dependent pathways and 2) use a combination approach that will shut down alternative mechanisms that lead to resistance. ... Read more

Abstract: Infectious pathogens have been linked to the genesis of malignancy in a variety of different settings. Initial studies in virology led to the important discovery of key genetic alterations underlying common malignancies, and further, lent support to the notion that malignancy can be promoted by the process of viral infection and cellular transformation. In this review, we summarize a series of hematologic malignancies with derivations from and associations with infectious organisms. Among these are a variety of lymphomas, including Hodgkin's Disease, Burkitt lymphoma, and a host of other non-Hodgkin's lymphomas. Through innovative and ground-breaking studies, some of these malignancies have been directly linked to viral infection, such as the Epstein-Barr virus (EBV), while others have been merely associated with infection through epidemiologic studies and case-reports. Some malignancies have been demonstrated to be caused by viral infection, such as adult T-cell leukemia and lymphoma (ATLL), which is caused by the human T cell lymphotropic virus type I (HTLV-I), in certain endemic area. In the future, additional malignant states may be found to be associated with infectious etiology, which could allow for novel approaches to prevention and treatment. ... Read more

Abstract: The hallmark of Ewing's sarcoma (EWS) is a translocation -- t(11;22)(q24;q12) -- that most frequently results in the EWS/FLI1 aberrant chimeric gene. Because EWS afflicts young patients, it stands out among the diverse sarcoma subtypes. The frontline, standard-of-care cytotoxic chemotherapy regimens produce minimal benefit in patients with metastases at presentation or those with relapsed disease. While the outcomes of chemorefractory EWS patients are generally poor, recent developments have led to the promising use of targeted therapy. Specifically, inhibition of insulin-like growth factor 1 receptor (IGF1R) signaling and the mammalian target of rapamycin (mTOR) pathways has emerged as a targeted therapy in EWS, with select patients experiencing dramatic therapeutic responses. However, targeted therapies in general, and these responders in particular, are faced with the ultimate conundrum of eventual resistance. To optimize response, combining IGF1R and mTOR inhibitor-based regimens with chemotherapy in the upfront setting in newly diagnosed high-risk EWS may clarify the true benefit of IGF1R inhibitors in these patients. Another option is to explore novel targeted multikinase inhibitors and poly(ADP-ribose) polymerase (PARP) inhibitors, which have experienced a surge in supporting preclinical data. Drugs inhibiting the downstream targets of EWS/FLI1 are also in preclinical development. However, ultimately, the underlying biomarker correlates of resistance and response must be delineated along with ways to overcome them. Novel agents, together with integration of advances in multimodal approaches (including surgery and radiation), as well as offering targeted therapies early in the disease course represent new strategies for confronting the challenges of EWS. ... Read more

Abstract: Gastrointestinal stromal tumors (GIST) are the most frequent sarcoma and were recognized as distinct molecular entities in 1998. Following the identification of driving molecular alterations in KIT, imatinib was rapidly introduced for the treatment of GIST, and became the paradigm of molecularly targeted therapies for solid tumors. While surgery was the only known effective treatment in 1998, two drugs are approved by the FDA and EMA in 2012 for the treatment of localized and advanced forms of this disease. Imatinib has been shown to provide a high level of clinical efficacy in patients with advanced GIST, a median progression-free survival (PFS) of 2 years and median overall survival close to 5 years, with 20% patients progression-free after 10 years of treatment. Imatinib has also been proven to improve overall survival and reduce the risk of relapse in localized GIST at high risk for relapse after resection. Sunitinib is indicated in advanced GIST after failure of imatinib, and provided a median PFS close to 6 months after imatinib failure. However, there is an important variability in the molecular and genetic characteristics that drive the pathogenesis of GIST, allowing thus for the identification of distinct molecular subtypes of GIST with different prognosis and sensitivity to the targeted treatments. Different strategies are now recommended in these different molecular subtypes of GIST which must be recognized as different entities regarding sensitivity to tyrosine kinase inhibitors and treatment decisions. This fragmentation of a yet recently recognized disease entity illustrates to strong trend of fragmentation in nosology of cancers, even in rare tumors such as GIST. For this aspect also, GIST is again a paradigmatic model for oncology, as many tumors with a higher prevalence will be fragmented in different molecular subsets and are going to become rare disease in the years to come. ... Read more

Abstract: Photodynamic therapy (PDT) has emerged as an alternative modality for cancer treatment. PDT works by initiating damaging oxidation or redox-sensitive pathways to trigger cell death. PDT can also regulate tumor angiogenesis and modulate systemic antitumor immunity. The drawbacks to PDT -- photosensitizer toxicity, a lack of selectivity and efficacy of photosensitizers, and a limited penetrance of light through deep tissues -- are the same pitfalls associated with diagnostic imaging. Developments in the field of nanotechnology have generated novel platforms for optimizing the advantages while minimizing the disadvantages of PDT. Calcium phosphosilicate nanoparticles (CPSNPs) represent an optimal nano-system for both diagnostic imaging and PDT. In this review, we will discuss how CPSNPs can enhance optical agents and serve as selective, non-toxic, and functionally stable photosensitizers for PDT. We will also examine novel applications of CPSNPs and PDT for the treatment of leukemia to illustrate their potential utility in cancer therapeutics. ... Read more

Abstract: Among splenic lymphomas with circulating cells presenting cytoplasmic projections, a homogeneous clinico-pathological entity has been recently individualized as Splenic Diffuse Red Pulp Lymphomas (SDRPL) and introduced in the provisional "unclassifiable splenic lymphoma" category of the current updated WHO classification until more is known. SDRPL presents characteristic circulating basophilic villous lymphocytes and diffuse infiltration of the splenic red pulp, distinct from Splenic Marginal Zone Lymphoma (SMZL) and Hairy Cell Leukemia (HCL), but reminiscent of HCL-Variant (HCL-V). Series of SDRPL remain sparse in the literature and controversies exist about the relationship with other splenic lymphomas. Distinction of these disorders at diagnosis can be difficult, but an adequate diagnosis is important due to differences in patient management and clinical outcome. Especially, BRAF mutations have been detected in almost all patients with HCL that may have implications for pathogenesis, diagnosis, and targeted therapy. This review will report literature data and discuss the differential diagnosis, particularly with HCL-V. ... Read more

Abstract: The study of microRNA (miRNA) regulation in the pathogenesis of autoimmune diseases and hematopoietic malignancies provides new understanding of the mechanisms of disease and is currently the focus of many researchers in the field. Autoimmune disorders and cancers of immune system comprise a wide range of genetically complex diseases that share certain aspects of dysregulated genetic networks, most notably deactivation of apoptosis. miRNA mechanisms control gene expression at the post-transcriptional level, linking mRNA processing and gene function. Considerable amount of data have been accumulated that indicate that the alteration of miRNA expression closely mirrors the development of immune system diseases and is likely to play a role in their pathogenesis. However, a knowledge gap remains in our understanding of how miRNA dysregulation and the specific effects of miRNAs on target gene expression underlay the disease phenotype. Here we review a number of studies describing miRNA alterations in autoimmune diseases and hematopoietic cancers and discuss potential miRNA-regulated mechanisms that differentially influence the development of autoimmunity as compared to cancer progression. ... Read more

Abstract: Interest in pathogenesis of progressive multifocal leukoencephalopathy (PML) followed the observation of the high risk for the disease in HIV infection and the recent observation of an association with a variety of newer therapeutic modalities, e.g., natalizumab, an α4β1 integrin inhibitor, and efalizumab, an anti-CD11a monoclonal antibody. Any hypothesis of PML pathogenesis must account for a number of facts. Firstly, the causative agent JC virus is ubiquitously present, yet only a vanishingly small number of infected persons develop the disease. Secondly, disorders of cell-mediated immunity increase the risk of the disease, particularly HIV infection. Impaired innate immunity is not a risk for PML, and antibodies against JC virus are not protective. Thirdly, a latent period of several months appears necessary following the administration of natalizumab and efalizumab before PML develops. Fourthly, restoration of the immune system can arrest the PML. It is possible that infection with JC virus occurs with a form of the virus shed in the urine of as many as 40% of all adults and present in sewage worldwide. Once acquired, perhaps through an oropharyngeal route, it may replicate and disseminate. A neurotropic form of JC virus that replicates in glial tissues causes PML when immunosurveillance is impaired. There are many unanswered questions with respect to PML pathogenesis. How is virus acquired? What tissues are infected? What is the origin of the neurotropic form? When does virus enter brain? What is the role of central nervous system immunosurveillance? The lack of an animal model has made answering these questions challenging. ... Read more