Background: Little is known about the effects of chemotherapeutic drugs on DNA methylation status of leukocytes, which may be predictive of treatment benefits and toxicities. Based on a prospective national study, we characterize the changes in leukocyte DNA methylome from pre-to post-chemotherapy (approximately 4 months apart) in 93 patients treated for early stage breast cancer and 48 matched non-cancer controls. We further examined significant methylation changes with perceived cognitive impairment, a clinically significant problem related to cancer and chemotherapy. Results: Approximately 4.2% of the CpG sites measured using the Illumina 450K methylation array underwent significant changes after chemotherapy (p < 1e-7), in comparison to a stable DNA methylome in controls. Postchemotherapy, the estimated relative proportions of B cells and CD4 + T cells were decreased by a median of 100% and 39%, respectively, whereas the proportion of monocytes was increased by a median of 91%. After controlling for leukocyte composition, 568 CpGs from 460 genes were still significantly altered following chemotherapy. With additional adjustment for chemotherapy regimen, cumulative infusions, growth factors, and steroids, changes in four CpGs remained significant, including cg16936953 in VMP1/MIR21, cg01252023 in CORO1B, cg11859398 in SDK1, and cg19956914 in SUMF2. The most significant CpG, cg16936953, was also associated with cognitive decline in breast cancer patients. Conclusions: Chemotherapy profoundly alters the composition and DNA methylation landscape of leukocytes in breast cancer patients. Our results shed light on the epigenetic response of circulating immune cell populations to cytotoxic chemotherapeutic drugs and provide possible epigenetic links to the degeneration of cognitive function associated with chemotherapy.

OBJECTIVES To evaluate relationships between frailty and cognition longitudinally in adults 50 years and older with breast cancer receiving chemotherapy. DESIGN Secondary analysis of a prospective longitudinal observational study. SETTING University of Rochester NCI Community Oncology Research Program community oncology clinics. PARTICIPANTS Patients with breast cancer age 50 and older receiving adjuvant/neoadjuvant chemotherapy (n = 376) and age‐matched controls without cancer (n = 234). MEASUREMENTS Frailty was assessed using a modified frailty score from self‐reported assessments (weakness, exhaustion, physical activity, and gait speed). Cognition was assessed by patient report (Functional Assessment of Cancer Therapy‐Cognition [FACT‐Cog]) and objective measures. Frailty and cognition were measured at three time points (prechemotherapy [A1], postchemotherapy [A2], and 6 months postchemotherapy [A3]; similar time interval for controls). Linear regression models evaluated associations between frailty and cognition adjusting for covariates. RESULTS The average age was 59 years (standard deviation = 6.4 y). At baseline, patients with cancer had a higher mean frailty score (1.21 vs .73; P < .001) and lower mean FACT‐Cog score (158.4 vs 167.3; P < .001) compared with controls. Objective cognitive measures were not statistically different. Longitudinal decline in FACT‐Cog between A1 and A2 (P < .05) and between A1 and A3 (P < .01) was associated with increased frailty score in patients compared with controls. Longitudinal worsening in Controlled Oral Word Association (P < .05) and Trail‐Making Test (P < .01) were associated with an increase in frailty between A1 and A2 in patients compared with controls; longitudinal decline in the Delayed Match to Sample test was associated with an increase in frailty between A1 and A3 (P < .05) in patients compared with controls. This finding remained significant for a subset analysis of those aged 65 and older. CONCLUSION In patients with breast cancer aged 50 and older, longitudinal decline in FACT‐Cog and objective measures of attention and memory were associated with increased frailty during treatment and up to 6 months posttreatment. Overall, our study suggests cognition and frailty are both important factors to assess in breast cancer patients. J Am Geriatr Soc 67:928–936, 2019.

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In the present study, we have assessed, in a comparative manner, the in vitro proliferation and expansion potentials of hematopoietic progenitor cells (HPC) present in mobilized peripheral blood from normal subjects (MPB-n; n = 18) and cancer patients (MPB-c; n = 18). The latter included patients with breast cancer (BrCa; n = 8), Hodgkin disease (HD; n = 4), non-Hodgkin lymphoma (NHL; n = 3), and acute myeloid leukemia (AML; n = 3). Progenitor cells from normal bone marrow (BM) and umbilical cord blood (UCB) were included as controls. HPC, enriched by a negative selection procedure, were cultured for 25 days, in serum-free liquid media in the presence of a cytokine combination including early- and late-acting cytokines. Our results demonstrate that the in vitro biological properties of progenitor cells present in MPB differ, depending on whether they are derived from healthy individuals, from patients with solid tumors, or from patients with hematological neoplasias. Among all cell sources analyzed, UCB-derived progenitors showed the greatest proliferation and expansion potentials (1000-fold increase in total cell numbers on day 15, and a 22-fold increase in myeloid progenitor cell numbers, at day 10). Progenitor cells present in MPB from hematologically normal individuals showed proliferation and expansion potentials comparable to those of HPC from normal BM (500-fold increase in total cell numbers on day 15, and a 14-fold increase in myeloid progenitor cell numbers, at day 10). The proliferation/expansion potentials of MPB progenitors from BrCa patients were also within the normal range, although in the lower levels (327-fold increase in total cell numbers, on day 15, and 11.8-fold increase in myeloid progenitors, at day 10). In contrast, progenitors present in MPB from patients with HD, NHL, and especially AML, showed reduced in vitro capacities (119-, 102-, and 51-fold increase in total cell numbers, respectively; and 8-, 4-, and 2.6-fold increase in myeloid progenitor cells, respectively). To our knowledge, this is the first report in which the in vitro proliferation and expansion potentials of HPC from MPB from normal subjects and cancer patients are assessed simultaneously in a comparative manner.

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