Exploring the boundaries of precision haemato-oncology : The case of FLT3 length mutated acute myeloid leukaemia

This dissertation explores the astounding biological heterogeneity of acute myeloid leukaemia (AML). In three research papers, we study FLT3 length mutated (LM) AML to contribute to the characterisation of genetic diversity between patients but also within the same patient as the disease develops over time. AML is a rare but severe blood cancer for which outcome is poor. In haemato-oncology as in other cancer fields, the imaginary of precision medicine is a potent force that provides direction to research as well as the development of clinical practice. Specifically, the hope is to tailor cancer management by molecular profiling and therapeutic targeting of actionable aberrations. In the case of AML, the validity and utility of this approach is an open empirical question. The aim of this dissertation is to explore the biological boundaries of precision oncology in the context of AML. I have pursued this aim through empirical characterisation of AML as a heterogeneous and dynamic phenomenon (in the research papers) and a literature study and theoretical reflection on the relationship between that empirical characterisation and available conceptual frameworks of cancer (in the synthesis part of the dissertation). Somatic mutation theory, tumour evolution theory and cancer stem cell theory were identified as the prevailing conceptual frameworks representing variants of explanatory models in AML. These theories also provide justification for the clinical approaches related to precision haemato-oncology. The synthesis provides an overview of empirical FLT3-LM AML research poorly accounted for by these prevailing models, including intra-leukaemic plurality of FLT3-LMs as well as clinico-pathological relationships that suggest context-dependency with regards to FLT3-LM properties. Indeed, in Paper I we confirm the finding that AML patients may have several FLT3-LMs. In Paper II, we show hitherto undiscovered sex differences in genetic profiles of FLT3-LM AML. In Paper III, a single patient is followed through the course of his disease to reveal how genetically diverse cell populations may initiate leukaemia in animal models. These findings pose challenges to the understanding of FLT3-LMs as causal contributors in AML pathogenesis. A major conclusion of this dissertation is that somatic mutation theory is not a sufficient conceptual framework for AML. Evolutionary perspectives seem called for, and the dissertation proposes that a selection-centric perspective to further the understanding and interpretation of FLT3- LM AML pathogenesis, conceptualising both cancer cells and cancer as dynamic phenomena rather than confined entities. Based on this I propose a shift towards characterisation of permissive conditions facilitating the emergence and persistence of disease

Filled with Desire, Perceive Molecules

Could there be a Taoist philosophy of Acute Myeloid Leukaemia (AML)? This chapter discusses why a molecular treatment of AML has been so hard to find but still so intensely researched, and exposes some of the ethical dilemmas involved when treating this aggressive blood cancer. It does so by applying the concepts and style of the ancient Chinese masterpiece Tao Te Ching, the essence of which is that the real world is richer than what can be expressed by language.publishedVersio

Titrating complex mass cytometry panels

We describe here a simple and efficient antibody titration approach for cell‐surface markers and intracellular cell signaling targets for mass cytometry. The iterative approach builds upon a well‐characterized backbone panel of antibodies and analysis using bioinformatic tools such as SPADE. Healthy peripheral blood and bone marrow cells are stained with a pre‐optimized “backbone” antibody panel in addition to the progressively diluted (titrated) antibodies. Clustering based on the backbone panel enables the titration of each antibody against a rich hematopoietic background and assures that nonspecific binding and signal spillover can be quantified accurately. Using a slightly expanded backbone panel, antibodies quantifying changes in transcription factors and phosphorylated antigens are titrated on ex vivo stimulated cells to optimize sensitivity and evaluate baseline expression. Based on this information, complex panels of antibodies can be thoroughly optimized for use on healthy whole blood and bone marrow and are easily adaptable to the investigation of samples from for example clinical studies.publishedVersio

Cancer Biomarkers: Ethics, Economics and Society

publishedVersio

Reframing cancer: challenging the discourse on cancer and cancer drugs—a Norwegian perspective

Background As the range of therapeutic options in the field of oncology increases, so too does the strain on health care budgets. The imbalance between what is medically possible and financially feasible is frequently rendered as an issue of tragic choices, giving rise to public controversies around health care rationing. Main body We analyse the Norwegian media discourse on expensive cancer drugs and identify four underlying premises: (1) Cancer drugs are de facto expensive, and one does not and should not question why. (2) Cancer drugs have an indubitable efficacy. (3) Any lifetime gained for a cancer patient is an absolute good, and (4) cancer patients and doctors own the truth about cancer. Applying a principle-based approach, we argue that these premises should be challenged on moral grounds. Within the Norwegian public discourse, however, the premises largely remain unchallenged due to what we find to be unjustified claims of moral superiority. We therefore explore alternative framings of the issue of expensive cancer drugs and discuss their potential to escape the predicament of tragic choices. Conclusions In a media discourse that has seemingly stagnated, awareness of the framings within it is necessary in order to challenge the current tragic choices predicament the discourse finds itself in. In order to allow for a discourse not solely concerned with the issue of tragic choices, the premises that underlie it must be subjected to critical examination. As the field of oncology advances rapidly, we depend on a discussion of its opportunities and challenges that is meaningful, and that soberly addresses the future of cancer care—both its potential and its limits

Targeted Therapy of FLT3 in Treatment of AML—Current Status and Future Directions

Internal tandem duplications (ITDs) of the gene encoding the Fms-Like Tyrosine kinase-3 (FLT3) receptor are present in approximately 25% of patients with acute myeloid leukemia (AML). The mutation is associated with poor prognosis, and the aberrant protein product has been hypothesized as an attractive therapeutic target. Various tyrosine kinase inhibitors (TKIs) have been developed targeting FLT3, but in spite of initial optimism the first generation TKIs tested in clinical studies generally induce only partial and transient hematological responses. The limited treatment efficacy generally observed may be explained by numerous factors; extensively pretreated and high risk cohorts, suboptimal pharmacodynamic and pharmacokinetic properties of the compounds, acquired TKI resistance, or the possible fact that inhibition of mutated FLT3 alone is not sufficient to avoid disease progression. The second-generation agent quizartinb is showing promising outcomes and seems better tolerated and with less toxic effects than traditional chemotherapeutic agents. Therefore, new generations of TKIs might be feasible for use in combination therapy or in a salvage setting in selected patients. Here, we sum up experiences so far, and we discuss the future outlook of targeting dysregulated FLT3 signaling in the treatment of AML

Targeted Therapy of FLT3 in Treatment of AML—Current Status and Future Directions

Internal tandem duplications (ITDs) of the gene encoding the Fms-Like Tyrosine kinase-3 (FLT3) receptor are present in approximately 25% of patients with acute myeloid leukemia (AML). The mutation is associated with poor prognosis, and the aberrant protein product has been hypothesized as an attractive therapeutic target. Various tyrosine kinase inhibitors (TKIs) have been developed targeting FLT3, but in spite of initial optimism the first generation TKIs tested in clinical studies generally induce only partial and transient hematological responses. The limited treatment efficacy generally observed may be explained by numerous factors; extensively pretreated and high risk cohorts, suboptimal pharmacodynamic and pharmacokinetic properties of the compounds, acquired TKI resistance, or the possible fact that inhibition of mutated FLT3 alone is not sufficient to avoid disease progression. The second-generation agent quizartinb is showing promising outcomes and seems better tolerated and with less toxic effects than traditional chemotherapeutic agents. Therefore, new generations of TKIs might be feasible for use in combination therapy or in a salvage setting in selected patients. Here, we sum up experiences so far, and we discuss the future outlook of targeting dysregulated FLT3 signaling in the treatment of AML

Sex disparity in acute myeloid leukaemia with FLT3 internal tandem duplication mutations: implications for prognosis

Incidence, molecular presentation and outcome of acute myeloid leukaemia (AML) are influenced by sex, but little attention has been directed at untangling sex-related molecular and phenotypic differences between female and male patients. While increased incidence and poor risk are generally associated with a male phenotype, the poor prognostic FLT3 internal tandem duplication (FLT3-ITD) mutation and co-mutations with NPM1 and DNMT3A are overrepresented in female AML. Here, we have investigated the relationship between sex and FLT3-ITD mutation status by comparing clinical data, mutational profiles, gene expression and ex vivo drug sensitivity in four cohorts: Beat AML, LAML-TCGA and two independent HOVON/SAKK cohorts, comprising 1755 AML patients in total. We found prevalent sex-associated molecular differences. Co-occurrence of FLT3-ITD, NPM1 and DNMT3A mutations was overrepresented in females, while males with FLT3-ITDs were characterized by additional mutations in RNA splicing and epigenetic modifier genes. We observed diverging expression of multiple leukaemia-associated genes as well as discrepant ex vivo drug responses, suggestive of discrete functional properties. Importantly, significant prognostication was observed only in female FLT3-ITD-mutated AML. Thus, we suggest optimization of FLT3-ITD mutation status as a clinical tool in a sex-adjusted manner and hypothesize that prognostication, prediction and development of therapeutic strategies in AML could be improved by including sex-specific considerations.publishedVersio

Sex disparity in acute myeloid leukaemia with FLT3 internal tandem duplication mutations: implications for prognosis

Incidence, molecular presentation and outcome of acute myeloid leukaemia (AML) are influenced by sex, but little attention has been directed at untangling sex-related molecular and phenotypic differences between female and male patients. While increased incidence and poor risk are generally associated with a male phenotype, the poor prognostic FLT3 internal tandem duplication (FLT3-ITD) mutation and co-mutations with NPM1 and DNMT3A are overrepresented in female AML. Here, we have investigated the relationship between sex and FLT3-ITD mutation status by comparing clinical data, mutational profiles, gene expression and ex vivo drug sensitivity in four cohorts: Beat AML, LAML-TCGA and two independent HOVON/SAKK cohorts, comprising 1755 AML patients in total. We found prevalent sex-associated molecular differences. Co-occurrence of FLT3-ITD, NPM1 and DNMT3A mutations was overrepresented in females, while males with FLT3-ITDs were characterized by additional mutations in RNA splicing and epigenetic modifier genes. We observed diverging expression of multiple leukaemia-associated genes as well as discrepant ex vivo drug responses, suggestive of discrete functional properties. Importantly, significant prognostication was observed only in female FLT3-ITD-mutated AML. Thus, we suggest optimization of FLT3-ITD mutation status as a clinical tool in a sex-adjusted manner and hypothesize that prognostication, prediction and development of therapeutic strategies in AML could be improved by including sex-specific considerations

Titrating complex mass cytometry panels

We describe here a simple and efficient antibody titration approach for cell‐surface markers and intracellular cell signaling targets for mass cytometry. The iterative approach builds upon a well‐characterized backbone panel of antibodies and analysis using bioinformatic tools such as SPADE. Healthy peripheral blood and bone marrow cells are stained with a pre‐optimized “backbone” antibody panel in addition to the progressively diluted (titrated) antibodies. Clustering based on the backbone panel enables the titration of each antibody against a rich hematopoietic background and assures that nonspecific binding and signal spillover can be quantified accurately. Using a slightly expanded backbone panel, antibodies quantifying changes in transcription factors and phosphorylated antigens are titrated on ex vivo stimulated cells to optimize sensitivity and evaluate baseline expression. Based on this information, complex panels of antibodies can be thoroughly optimized for use on healthy whole blood and bone marrow and are easily adaptable to the investigation of samples from for example clinical studies