Abstract 3215: BloodCCD is a novel biomarker to detect circadian rhythm disruption in cancer survivors with insomnia

Introduction: Insomnia is a significant co-morbidity for cancer survivors, and can independently reduce lifespan, but there is currently no objective biochemical measure of insomnia. Circadian rhythms are 24 hour cycles that control physiologic processes including sleep. Disrupted circadian rhythms have been proposed as a cause of insomnia. Here, we describe the use of a novel biomarker, BloodCCD, to assess circadian rhythms from RNA-sequencing of blood samples from two independent clinical trials and one observational study. BloodCCD was adapted from Clock Correlation Distance (CCD), which assesses normal progression of the molecular circadian clock from gene expression in tissue samples. We used BloodCCD to interrogate whether 1) cancer patients and survivors with insomnia have disrupted circadian rhythms compared to healthy good sleepers, and 2) whether the degree of circadian disruption correlates with severity of insomnia in survivors. Methods: For BloodCCD analysis, time-series RNA-sequencing of human blood from healthy subjects were used to construct a reference correlation matrix of 42 genes which oscillate with 24-hour rhythms. To assess the Aims, RNA-sequencing from patient and survivor blood samples were compared to this reference correlation matrix to generate a BloodCCD score. A higher score indicates a further distance from a healthy clock, and thus clock disruption. For the first Aim, blood RNA-sequencing from cancer patients undergoing active treatment and survivors at least 2-months post-treatment and with insomnia were compared to healthy good sleepers. For the second Aim, blood RNA-sequencing from cancer survivors with insomnia were assessed, stratified by Insomnia Severity Index (ISI) Score into mild (ISI 10-14), moderate (ISI 15-21), and severe (ISI 22-28) insomnia. Results: Patients (n=28, 100% prostate cancer) and cancer survivors (n=497, ~72% breast cancer) had higher BloodCCD scores, indicating disrupted circadian clock, compared to healthy good sleepers (n=14), with scores of 9.98, 7.99, and 4.13, respectively. When cancer survivors were stratified by insomnia severity, those with severe insomnia (ISI 22-28) had the highest BloodCCD, 9.00, while those with moderate insomnia (ISI 15-21) had a score of 8.24 and those with mild insomnia (ISI 10-14) had the lowest score of 7.93, indicating that survivors with severe insomnia had a more disrupted circadian clock. All BloodCCD values were p < 0.001 for each value compared to reference c