Primer on medical genomics. Part XIII: Ethical and regulatory issues

Ethics in the new genomics era has become an increasingly complex subject that often arouses passion and confusion. Although 50 years have elapsed since the elucidation of the DNA molecule, the recent near-complete sequencing of the human genome has sharply accelerated the incorporation of genetics into the medical mainstream. Along with these scientific advances, however, have surfaced challenges, liabilities, and issues regarding the processing and management of genetic information as they relate to core ethical principles such as respect for autonomy, beneficence, nonmaleficence, and justice. Institutions and state and federal governments have initiated systematic and preemptive measures in education, resource development, and protective legislation to address these cardinal ethical issues. Genetic research is also being scrutinized carefully by institutional review boards, an activity that should not be perceived as being adversarial but rather as a protective shield for investigators and research participants alike. Ultimately, it is hoped that genomics medicine will diminish rather than enhance existing sex-, race-, and socioeconomic class-based inequities in health care access and delivery. This article describes some but not all aspects of the ethical, legal, and social implications of genomics in clinical practice.     

TG101209, a novel JAK2 inhibitor,has significant in vitro activity in multiple myeloma and displays preferential cytotoxicity for CD45+ myeloma cells

Interaction of myeloma cells with the bone marrow microenvironment is mediated in large part through different cytokines, especially VEGF and IL6. These cytokines, especially IL6, leads to upregulation of the JAK/STAT pathway in myeloma cell, contributing to increased proliferation, decreased apoptosis, and acquired drug resistance. Here, we examined the preclinical activity of a novel JAK2 inhibitor TG101209. TG101209 induced dose‐ and time‐dependent cytotoxicity in a variety of multiple myeloma (MM) cell lines. The induction of cytotoxicity was associated with inhibition of cell cycle progression and induction of apoptosis in myeloma cell lines and patient‐derived plasma cells. Evaluation of U266 cell lines and patient cells, which have a mix of CD45 positive and negative cells, demonstrated more profound cytotoxicity and antiproliferative activity of the drug on the CD45+ population relative to the CD45? cells. Exploring the mechanism of action of TG101209 indicated downregulation of pJak2, pStat3, and Bcl‐xl levels with upregulation of pErk and pAkt levels indicating cross talk between signaling pathways. TG101209, when used in combination with the PI3K inhibitor LY294002, demonstrated synergistic cytotoxicity against myeloma cells. Our results provide the rationale for clinical evaluation of TG101209 alone or in combination with PI3K/Akt inhibitors in MM. Am. J. Hematol., 2010. © 2010 Wiley‐Liss, Inc.     

The diagnostic interface between histology and molecular tests in myeloproliferative disorders

PURPOSE OF REVIEW: The sighting of the Philadelphia chromosome in 1960, later shown to harbor the BCR-ABL mutation in chronic myeloid leukemia, is arguably the most seminal contribution to molecular oncology. In the decades that followed, other cytogenetic and molecular disease markers have been described and effectively incorporated into routine diagnostic tests. This review discusses how this process is unfolding in myeloproliferative disorders. RECENT FINDINGS: In 2003, a karyotypically-occult FIP1L1-PDGFRA was reported in a subset of patients with blood eosinophilia and bone marrow mastocytosis; this mutation has since joined several other molecular markers for eosinophilic (e.g. PDGFRbeta- and FGFR1-rearrangements) and mast cell (e.g. KITD816V) disorders. In 2005, JAK2V617F was described in polycythemia vera and other BCR-ABL myeloproliferative disorders; the particular discovery has already had a major impact on current diagnostic approaches in polycythemia vera. These remarkable molecular discoveries are both redefining and reinforcing the diagnostic role of bone marrow histopathology. SUMMARY: Recent progress in the molecular pathogenesis of myeloproliferative disorders calls for a paradigm shift in traditional diagnostics, which is based on subjective technologies or assignment to a 'consensus'-based ever-changing list of inclusionary and exclusionary criteria. Routine clinical practice might be better served by diagnostic algorithms that incorporate molecular disease markers, which complement histological impression.     

Thrombosis in myeloproliferative disorders: prevalence, prognostic factors, and the role of leukocytes and JAK2V617F

An underlying myeloproliferative disorder (MPD), especially polycythemia vera (PV) or essential thrombocythemia (ET), is a risk factor for thrombosis. Considering large selected studies, prevalence rates for major thrombosis, at time of diagnosis, range from approximately 34 to 39% for PV and 10 to 29% for ET; the corresponding figures for thrombosis at follow-up are approximately 8 to 19% for PV and 8 to 31% for ET. In all instances, arterial events were more frequent than venous events. In both PV and ET, advanced age and history of thrombosis are independent predictors of recurrent thrombosis. In addition, leukocytosis, but not thrombocytosis, has been identified as a potential risk factor for thrombosis in both diseases. The particular observation is consistent with the laboratory demonstration, in these disorders, of increased number of activated granulocytes and granulocyte-platelet aggregates, upregulation of platelet P-selectin and tissue factor expression by granulocytes, and the antithrombotic value of hydroxyurea therapy. Most recently, a JAK2 gain-of-function mutation ( JAK2V617F) was described in virtually all patients with PV and approximately 50% of those with ET. Whether the presence of this specific mutation or its allele burden modifies the risk of thrombosis in patients with MPDs currently is under investigation.     

Proposals and rationale for revision of the World Health Organization diagnostic criteria for polycythemia vera, essential thrombocythemia, and primary myelofibrosis: recommendations from an ad hoc international expert panel

The Janus kinase 2 mutation, JAK2617V>F, is myeloid neoplasm-specific; its presence excludes secondary polycythemia, thrombocytosis, or bone marrow fibrosis from other causes. Furthermore, JAK2617V>F or a JAK2 exon 12 mutation is present in virtually all patients with polycythemia vera (PV), whereas JAK2617V>F also occurs in approximately half of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF). Therefore, JAK2 mutation screening holds the promise of a decisive diagnostic test in PV while being complementary to histology for the diagnosis of ET and PMF; the combination of molecular testing and histologic review should also facilitate diagnosis of ET associated with borderline thrombocytosis. Accordingly, revision of the current World Health Organization (WHO) diagnostic criteria for PV, ET, and PMF is warranted; JAK2 mutation analysis should be listed as a major criterion for PV diagnosis, and the platelet count threshold for ET diagnosis can be lowered from 600 to 450 x 10(9)/L. The current document was prepared by an international expert panel of pathologists and clinical investigators in myeloproliferative disorders; it was subsequently presented to members of the Clinical Advisory Committee for the revision of the WHO Classification of Myeloid Neoplasms, who endorsed the document and recommended its adoption by the WHO.     

Risk-based management of myelodysplastic syndrome

Most adult patients with hematopoietic failure due to myelodysplastic syndrome (MDS) are treated with supportive care measures, including hematopoietic growth factors (epoetin alfa, darbepoetin alfa, filgrastim, pegfilgrastim, sargramostim), red blood cell or platelet transfusions, and antimicrobial agents. Allogeneic stem cell transplantation can be curative, but only a small subset of patients are eligible for transplantation, and until recently there were few options other than supportive care for transplant-ineligible patients. Since 2004, the US Food and Drug Administration (FDA) has approved three new therapies specifically for the indication of MDS: two DNA methyltransferase inhibitors (azacitidine and decitabine) and an immunomodulatory agent (lenalidomide). Several other drugs are used by clinicians for treatment of patients with MDS, but are not specifically FDA-approved for this indication. With several therapeutic options available, yet none of them effective in the majority of cases, it can be challenging for clinicians to choose the most appropriate treatment for an individual patient. Here we discuss a risk-based management approach to MDS that incorporates recent data regarding these new therapies. While many questions remain about the optimal use of newer agents, the long-standing perception of MDS as a syndrome where therapeutic nihilism is the only realistic approach is slowly beginning to change.     

Philadelphia chromosome mosaicism at diagnosis in chronic myeloid leukemia: clinical correlates and effect on imatinib mesylate treatment outcome

In chemotherapy-treated patients with chronic myeloid leukemia (CML), the karyotypic detection of Philadelphia chromosome (Ph)-negative metaphases at diagnosis (i.e. Ph mosaicism) is not considered significant as a prognostic factor for survival. In the current retrospective study, clinical correlates and prognostic relevance of Ph mosaicism were evaluated in 63 Ph-positive patients with CML, including 59 in chronic phase and 4 in accelerated phase, receiving imatinib mesylate as either first (n = 46) or second (n = 17) line therapy. Thirteen patients (21%) displayed Ph-negative metaphases at diagnosis and, compared to the other 50 patients with 100% Ph-positive metaphases, presented with significantly lower leukocyte count (p = 0.0004), circulating blast percentage (p = 0.02), and incidence of palpable splenomegaly (p = 0.02). Ph mosaicism did not correlate with other CML-pertinent prognostic factors including Sokal score (p = 0.4) or the presence of additional chromosome changes (p = 0.96) found in 10 patients (16%). Neither Ph mosaicism nor the presence of additional chromosome changes affected complete or partial cytogenetic remission rates to IM. Multivariable analysis identified Ph mosaicism as a risk factor for shortened survival. Due to the small sample size, the current preliminary observations require validation in a larger group of patients.