Citations

Abstract ABCB7 is a mitochondrial transporter that exports iron-sulfur (Fe-S) cluster intermediates from the mitochondria to the cytoplasm. Using CD2-iCre ABCB7 cKO mice, we found ABCB7 is required for early B cell development. These mice have a severe block in pro-B cell development at the Fr. C to Fr. C′ transition, with reduced expression of intracellular μ and pre-BCR. CD19-cre and CD23-cre ABCB7 cKO mice have normal B cell development and peripheral B cell populations, indicating ABCB7 is required only during early B cell development. We observed reduced expression of Runx1, Ikaros, Foxo1, E47 (E2A), and Pax5 in CD2-iCre ABCB7 cKO pro-B cells. Interestingly, we also observed decreased BACH2 expression, which indicates elevated heme synthesis is occurring in the absence of ABCB7. We hypothesize that in the absence of ABCB7, developing B cells enhance heme synthesis to dispose of accumulating mitochondrial iron. Using a hen egg lysozyme BCR transgene, we were able to rescue B cell development in CD2-iCre ABCB7 cKO mice. Intriguingly, at the age of 5–8 weeks old, CD2-iCre ABCB7 cKO mice become lethargic and hunched. CBCs reveal an increase in peripheral blood neutrophils. Both the spleen and bone marrow become highly infiltrated by CD11b+Ly6Glow/+Ly6C− cells that are immature and mature neutrophils. As other knockout mice with pro-B cell blocks do not have neutrophilia, we considered if increased iron or heme is responsible for our observation. As heme can stimulate TLR4, we propose that excess heme from developing ABCB7-deficent B cells activates macrophages. In support of this, hemin induced GM-CSF production in BMDM cultures. We are currently exploring the mechanism by which excess heme production can stimulate the production of neutrophils.

68 Background: Accrual of racial and ethnic minority patients (pts) to clinical trials has been an ongoing challenge in research. Barriers exist at many levels of engagement including trial availability, screening biases, strict enrollment criteria, and structural racism. Lack of trial diversity has led to less generalizable medical evidence, suboptimal data for toxicity and efficacy of cancer treatments, poorer outcomes and continued mistrust by communities of color in research processes that exclude or marginalize them. Site factors and study design strategies associated with successful recruitment of diverse study populations are understudied. Methods: Alliance A191901 is an RCT testing combinations of text and telephone support to promote endocrine therapy adherence among breast cancer survivors. It oversamples Black participants and those < 50 years at thresholds of 30% each. Administrative enrollment data was used to track and describe monthly accrual trajectory by race among the initial 50% of participants (n = 590) and to examine associations between % Black participants accrued and accruing site characteristics, including site type, geographic region, % Black population in the site’s zip code and volume of pts by race accrued to recent (2018-2019) Alliance trials, using χ2 tests. We also examined patterns of Black participant accrual before and after closure of the A191901 study to non-Black participants. Results: At 50% accrual, 124 sites had enrolled at least 1 participant. Among 590 participants, 9.7% were Black and 22.5% were < 50 years. Neither site type nor volume was associated with % Black participants recruited. Sites in the South recruited higher proportions of Blacks (19.0% vs 5.6% for Midwest, the lowest region, p < 0.001). Neighborhood racial composition was positively associated with accrual of Black participants (17.2% at sites from highest Black composition vs. 2.3% in lowest, p < 0.001). Recruitment trajectories of Black participants consistently lagged those of non-Black participants in the first half of the study; however, Black participants recruited per month numerically increased after the study reached target accrual of non-Blacks and closed to non-Black participants. Conclusions: Sites in neighborhoods and geographic regions with larger Black populations recruited higher proportions of Black participants, but site type and volume were not associated with recruitment of Black participants. Closure of non-Black study strata based on predetermined accrual targets may positively impact recruitment trajectories of Black participants, but further study is needed. Site selection based on neighborhood composition and geography may be an appropriate tool for increasing trial diversity. Support: UG1CA189823. Clinical trial information: NCT04379570.

6602 Background: Treatment advances have greatly improved survival and quality of life among blood cancer patients, yet significant financial costs are a growing concern. Methods: We conducted an observational, prospective survey in 2019-2020 to estimate the self-reported prevalence of financial difficulty among multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) patients and identify sociodemographic correlates of financial difficulty. Patients with an MM or CLL diagnosis >/= 18 years of age were recruited from NCI NCORP sites of care. Financial difficulty was measured in a previously validated single question from the EORTC QLQ C30 and a composite measure of five questions from the EORTC QLQ C30. Results: 521 MM and CLL patients were registered to the study, 416 patients were administered all or part of the patient survey, for an overall response rate of 79.8%. 16.8% of respondents reported experiencing financial difficulty in response to the single item question and 58.6% reported experiencing financial difficulty in response to the composite measure. Respondents reporting financial difficulty to both measures had reported household incomes of less than $60,000, identified their highest education levels as a high school diploma or GED, had more than one medical comorbidity and used an expensive oral chemotherapeutic agent to treat their blood cancer. Conclusions: Blood cancer patients treated at NCI NCORP sites are experiencing financial difficulties. Results of this study aim to inform physician, site of care and policy efforts to improve access among cancer patients. Clinical trial information: NCT03870633. [Table: see text]

After antigenic activation, quiescent naive CD4 + T cells alter their metabolism to proliferate. This metabolic shift increases production of nucleotides, amino acids, fatty acids, and sterols. Here, we show that histone deacetylase 3 (HDAC3) is critical for activation of murine peripheral CD4 + T cells. HDAC3-deficient CD4 + T cells failed to proliferate and blast after in vitro TCR/CD28 stimulation. Upon T-cell activation, genes involved in cholesterol biosynthesis are upregulated while genes that promote cholesterol efflux are repressed. HDAC3-deficient CD4 + T cells had reduced levels of cellular cholesterol both before and after activation. HDAC3-deficient cells upregulate cholesterol synthesis appropriately after activation, but fail to repress cholesterol efflux; notably, they overexpress cholesterol efflux transporters ABCA1 and ABCG1. Repression of these genes is the primary function for HDAC3 in peripheral CD4 + T cells, as addition of exogenous cholesterol restored proliferative capacity. Collectively, these findings demonstrate HDAC3 is essential during CD4 + T-cell activation to repress cholesterol efflux.

Iron-sulfur (Fe-S) clusters are cofactors essential for the activity of numerous enzymes including DNA polymerases, helicases, and glycosylases. They are synthesized in the mitochondria as Fe-S intermediates and are exported to the cytoplasm for maturation by the mitochondrial transporter ABCB7. Here, we demonstrate that ABCB7 is required for bone marrow B cell development, proliferation, and class switch recombination, but is dispensable for peripheral B cell homeostasis in mice. Conditional deletion of ABCB7 using Mb1-cre resulted in a severe block in bone marrow B cell development at the pro-B cell stage. The loss of ABCB7 did not alter expression of transcription factors required for B cell specification or commitment. While increased intracellular iron was observed in ABCB7-deficient pro-B cells, this did not lead to increased cellular or mitochondrial reactive oxygen species, ferroptosis, or apoptosis. Interestingly, loss of ABCB7 led to replication-induced DNA damage in pro-B cells, independent of VDJ recombination, and these cells had evidence of slowed DNA replication. Stimulated ABCB7-deficient splenic B cells from CD23-cre mice also had a striking loss of proliferation and a defect in class switching. Thus, ABCB7 is essential for early B cell development, proliferation, and class switch recombination.

8031 Background: New orally administered anticancer treatments have launched in recent years, promising gains in survival and quality of life, but with high prices.Financial difficulties encountered over the course of cancer diagnosis and treatment is a growing concern. These difficulties include inability to pay for basic necessities, presence of medical debt, and high out of pocket burdens relative to income. The primary objective of this study was to estimate the proportion of patients with multiple myeloma (MM) who experience financial difficulties in the past 12 months.Methods: Data collection entailed a comprehensive, theoretically grounded telephone survey and companion medical chart abstraction. Subjects included individuals with a current diagnosis of MM whose current or recent treatment included pharmaceutical-based care and who were not enrolled in a treatment-based trial. Practices eligible to recruit respondents included 44 NCORP affiliates of the Alliance. 14 geographically diverse NCORP affiliates participated between 11/2019 and 6/2020. The primary endpoint of the study was the proportion of subjects who reported financial difficulty in the past 12 months, as measured by the EORTC QLQ-C30 item #28. This proportion and 95% Wilson score confidence interval were estimated for all MM patients who responded to the financial difficulty question ((# reported financial difficulty)/(total # in that category who answered the question)). NCI Central IRB approved this study. Results: 393 subjects were recruited. 304 subjects completed the survey (77.4% response rate). Mean age was 67.5 years (SD 9.8), 143 (46.4%) were female, 24 (7.8%) self-reported race as ‘Black or African American’, 82 (26.6%) reported insured by government insurance Medicare only, 116 (38.2%) reported highest education as high school or below, and 94 (30.5%) reported high income. Mean time from diagnosis to survey enrollment was 3.6 years (SD 4.5). 292 (95.1%) were currently receiving treatment and 192 (62.5%) reported currently receiving a pre-defined ‘expensive’ oral pharmaceutical-based cancer treatment. 20.2% (95% CI:16.1%, 25.0%) reported financial difficulties. Conclusions: This is the first national study to systematically assess the prevalence of financial difficulties and its correlates among MM patients. Approximately 1 in 5 surveyed patients reported financial difficulties. Results of this study aim to inform efforts to improve financial navigation and resources for cancer patients.

Abstract Many tumors exhibit increased incorporation of sialic acids into cell-surface glycans, which impact the tumor microenvironment. Sialic acid immunoglobulin-like lectins (Siglec) are receptors that recognize sialic acids and modulate immune responses, including responses to tumors. However, the roles of individual sialyltransferases in tumorigenesis and tumor growth are not well understood. Here, we examined the sialyltransferase ST8Sia6, which generated α2,8-linked disialic acids that bind to murine Siglec-E and human Siglec-7 and -9. Increased ST8Sia6 expression was found on many human tumors and associated with decreased survival in several cancers, including colon cancer. Because of this, we engineered MC38 and B16-F10 tumor lines to express ST8Sia6. ST8Sia6-expressing MC38 and B16-F10 tumors exhibited faster growth and led to decreased survival, which required host Siglec-E. ST8Sia6 expression on tumors also altered macrophage polarization toward M2, including upregulation of the immune modulator arginase, which also required Siglec-E. ST8Sia6 also accelerated tumorigenesis in a genetically engineered, spontaneous murine model of colon cancer, decreasing survival from approximately 6 months to 67 days. Thus, ST8Sia6 expression on tumors inhibits antitumor immune responses to accelerate tumor growth.

Evidence for massage therapy (MT) in hospice patients remains limited. We conducted a prospective pilot study on MTs impact on quality of life of hospice patients and caregivers. Patient-caregiver dyads were enrolled if patients scored ≥5 on pain, depression, anxiety, or well-being using the revised Edmonton Symptom Assessment System Revised (ESAS-r). The patient received MT weekly for up to 3 massages with assessments completed at baseline, after each massage, and 1 week after the final massage for patients and at baseline and 1 week after final massage for caregivers. A satisfaction survey was completed at study completion. A pro-rated area under the curve (AUC) was utilized to assess the primary endpoints of change in ESAS-r for patient ratings of pain, depression and anxiety as well as the Linear Analogue Self-Assessment (LASA). Median difference scores (end of study value)-(baseline value) for each participant and caregiver were calculated. Of 27 patients and caregivers enrolled, 25 patients received MT. Fifteen patients completed all 3 MT sessions and were given the final symptom assessment and satisfaction survey and their caregivers completed final assessments. The proportion of patients considered success (AUC > baseline) in the primary endpoints were the following: pain 40.9%, depression 40.9%, anxiety 54.5%, LASA 54.5%. Median difference scores were largely zero indicating no significant temporal change in symptoms. Patients were highly satisfied with MT. This pilot study indicated that MT was a feasible and well-received intervention in our population of patients with inadequately controlled symptoms.