Spatial Mapping of Hematopoietic Clones in Human Bone Marrow

Clonal hematopoiesis (CH) is the expansion of somatically mutated cells in the hematopoietic compartment of individuals without hematopoietic dysfunction. Large CH clones (i.e., >2% variant allele fraction) predispose to hematologic malignancy, but CH is detected at lower levels in nearly all middle-aged individuals. Prior work has extensively characterized CH in peripheral blood, but the spatial distribution of hematopoietic clones in human bone marrow is largely undescribed. To understand CH at this level, we developed a method for spatially aware somatic mutation profiling and characterized the bone marrow of a patient with polycythemia vera. We identified the complex clonal distribution of somatic mutations in the hematopoietic compartment, the restriction of somatic mutations to specific subpopulations of hematopoietic cells, and spatial constraints of these clones in the bone marrow. This proof of principle paves the way to answering fundamental questions regarding CH spatial organization and factors driving CH expansion and malignant transformation in the bone marrow.

SIGNIFICANCE

CH occurs commonly in humans and can predispose to hematologic malignancy. Although well characterized in blood, it is poorly understood how clones are spatially distributed in the bone marrow. To answer this, we developed methods for spatially aware somatic mutation profiling to describe clonal heterogeneity in human bone marrow. See related commentary by Austin and Aifantis, p. 139.

The NUTRIENT Trial (NUTRitional Intervention among myEloproliferative Neoplasms): Results from a Randomized Phase I Pilot Study for Feasibility and Adherence

PURPOSE

Chronic inflammation is integral to myeloproliferative neoplasm (MPN) pathogenesis. JAK inhibitors reduce cytokine levels, but not without significant side effects. Nutrition is a low-risk approach to reduce inflammation and ameliorate symptoms in MPN. We performed a randomized, parallel-arm study to determine the feasibility of an education-focused Mediterranean diet intervention among patients with MPN.

EXPERIMENTAL DESIGN

We randomly assigned patients with MPN to either a Mediterranean diet or standard U.S. Dietary Guidelines for Americans (USDA). Groups received equal but separate education with registered dietician counseling and written dietary resources. Patients were prospectively followed for feasibility, adherence, and symptom burden assessments. Biological samples were collected at four timepoints during the 15-week study to explore changes in inflammatory biomarkers and gut microbiome.

RESULTS

The Mediterranean diet was as easy to follow for patients with MPN as the standard USDA diet. Approximately 80% of the patients in the Mediterranean diet group achieved a Mediterranean Diet Adherence Score of ≥8 throughout the entire active intervention period, whereas less than 50% of the USDA group achieved a score of ≥8 at any timepoint. Improvement in symptom burden was observed in both diet groups. No significant changes were observed in inflammatory cytokines. The diversity and composition of the gut microbiome remained stable throughout the duration of the intervention.

CONCLUSIONS

With dietician counseling and written education, patients with MPN can adhere to a Mediterranean eating pattern. Diet interventions may be further developed as a component of MPN care, and potentially incorporated into the management of other hematologic conditions.

SIGNIFICANCE

Diet is a central tenant of management of chronic conditions characterized by subclinical inflammation, such as cardiovascular disease, but has not entered the treatment algorithm for clonal hematologic disorders. Here, we establish that a Mediterranean diet intervention is feasible in the MPN patient population and can improve symptom burden. These findings warrant large dietary interventions in patients with hematologic disorders to test the impact of diet on clinical outcomes.

Targeting CHAF1B Enhances IFN Activity against Myeloproliferative Neoplasm Cells

Interferons (IFNs) are cytokines with potent antineoplastic and antiviral properties. IFNα has significant clinical activity in the treatment of myeloproliferative neoplasms (MPN), but the precise mechanisms by which it acts are not well understood. Here, we demonstrate that chromatin assembly factor 1 subunit B (CHAF1B), an Unc-51-like kinase 1 (ULK1)-interactive protein in the nuclear compartment of malignant cells, is overexpressed in patients with MPN. Remarkably, targeted silencing of CHAF1B enhances transcription of IFNα-stimulated genes and promotes IFNα-dependent antineoplastic responses in primary MPN progenitor cells. Taken together, our findings indicate that CHAF1B is a promising newly identified therapeutic target in MPN and that CHAF1B inhibition in combination with IFNα therapy might offer a novel strategy for treating patients with MPN.

Significance

Our findings raise the potential for clinical development of drugs targeting CHAF1B to enhance IFN antitumor responses in the treatment of patients with MPN and should have important clinical translational implications for the treatment of MPN and possibly in other malignancies.