The Analysis of Fatigue on Tyrosine Kinase Inhibitor Therapy in Chronic Myeloid Leukaemia

The therapeutic landscape of CML has evolved significantly, as a result of targeted TKI therapy, over the past 2 decades with patients now experiencing a near normal life expectancy due to achievement of deep molecular responses. As a consequence, the appropriate management of drug related adverse events to ensure minimal impact on quality of life has never been more vital. Fatigue and sleep disturbance are commonly described and whilst it is evident that there is a strong correlation between fatigue and TKI therapy, the mechanism which drives this remains unknown. In general, the prevalence of TKI induced fatigue and predicting factors is largely unexplored. This exploratory, pilot study aims to examine the rest-activity patterns, blood parameters and fatigue related serum biomarkers of CML patients affected by fatigue on TKI therapy, and aims to provide insight into the association between fatigue and sleep disturbance on treatment. The pilot study aims to recruit 25 patients with profound fatigue on TKI therapy, for a minimum of 6 months with an impact on their activities of daily living. Additionally, we will recruit 25 further patients (age, gender and TKI matched) as a control cohort, who also have a diagnosis of Chronic Phase CML with no symptoms of fatigue. Validated fatigue questionnaires will be used (Chalder fatigue scale and the Fisk fatigue impact scale), these are key diagnostic tools in Fatigue associated disorders. TKI- fatigue syndrome (TKI-FS) symptoms can emulate the clinical pattern of Chronic Fatigue Syndrome (CFS) and this project would delineate congruence between CFS and TKI-FS. The patient cohort will also undergo actigraphy, this will be used in this study as a validated objective sleep measure, this method uses sophisticated analysis of movement to infer sleep/wake patterns. Actigraphy is non-invasive and can be used for several weeks, alongside a daily sleep diary, allowing collection of naturalistic sleep data as a participant goes about their normal activities. In addition, serum biomarkers such as activin B is a member of the activin family of proteins, which belongs to the TGF-β superfamily of growth and differentiation factors; activin B has been shown to be a potential serum biomarker in fatigue related disorders. In addition, L-carnitine is a vital molecular component in many metabolic pathways, the majority of the total body carnitine is located within skeletal muscle. Impairments in L-carnitine synthesis, transport or metabolism can result in primary or secondary deficiencies, which ultimately results in muscle weakness and fatigue. Assessment of both of these serum biomarkers in both the fatigue and control cohort may shed insight on whether there are significant differences between those patients with TKI-FS and the control group.

The aim of the study is to use the above stated modalities in order to gain further insight into the association between fatigue and sleep disturbance in CML patients treated with TKI therapy, which can have a debilitating impact on patients.