Clonal Hematopoiesis and Therapy-Related Myeloid Neoplasms After Autologous Transplant for Hodgkin Lymphoma.

PURPOSE: Therapy-related myeloid neoplasm (t-MN) is a life-threatening complication of autologous peripheral blood stem cell transplantation (aPBSCT) for Hodgkin lymphoma (HL). Although previous studies have reported an association between clonal hematopoiesis (CH) in the infused PBSC product and subsequent post-aPBSCT risk of t-MN in patients with non-HL, information about patients with HL treated with aPBSCT is not available. METHODS: We constructed a retrospective cohort of 321 patients with HL transplanted at a median age of 34 years (range, 18-71). Targeted DNA sequencing of PBSC products performed for CH-associated or myeloid malignancy-associated genes identified pathogenic mutations in these patients. RESULTS: CH was identified in the PBSC product of 46 patients (14.3%) with most prominent representation of DNMT3A (n = 25), PPM1D (n = 7), TET2 (n = 7), and TP53 (n = 5) mutations. Presence of CH in the PBSC product was an independent predictor of t-MN (adjusted hazard ratio [aHR], 4.50 [95% CI, 1.54 to 13.19]). Notably all patients with TP53 mutations in the PBSC product developed t-MN, whereas none of the patients with DNMT3A mutations alone (without co-occurring TP53 or PPM1D mutations) did. Presence of TP53 and/or PPM1D mutations was associated with a 7.29-fold higher hazard of t-MN when compared with individuals carrying no CH mutations (95% CI, 1.72 to 30.94). The presence of TP53 and/or PPM1D mutations was also associated with a 4.17-fold higher hazard of nonrelapse mortality (95% CI, 1.25 to 13.87). There was no association between CH and relapse-related mortality. CONCLUSION: The presence of TP53 and/or PPM1D mutations in the PBSC product increases the risk of post-aPBSCT t-MN and nonrelapse mortality among patients with HL and may support alternative therapeutic strategies.

Clonal hematopoiesis in the setting of hematopoietic cell transplantation.

Clonal hematopoiesis (CH) in autologous transplant recipients and allogeneic transplant donors has genetic features and clinical associations that are distinct from each other and from non-cancer populations. CH in the setting of autologous transplant is enriched for mutations in DNA damage response pathway genes and is associated with adverse outcomes, including an increased risk of therapy-related myeloid neoplasm and inferior overall survival. Studies of CH in allogeneic transplant donors have yielded conflicting results but have generally shown evidence of potentiated alloimmunity in recipients, with some studies showing an association with favorable recipient outcomes.

Prevalence, Dynamics, and Prognostic Role of Clonal Hematopoiesis of Indeterminate Potential in Patients With Breast Cancer.

PURPOSE: Clonal hematopoiesis of indeterminate potential (CHIP) is frequent in patients with solid tumors. Prospective data about CHIP prevalence at breast cancer diagnosis and its dynamic evolution under treatment selective pressure are limited. PATIENTS AND METHODS: We performed targeted error-corrected sequencing on 614 samples from 380 patients with breast cancer. We investigated the dynamics of CHIP on prospectively collected paired samples from patients with early breast cancer (eBC) receiving chemotherapy (CT) or endocrine therapy (ET). We assessed the correlation of CHIP with survival in patients with metastatic triple-negative breast cancer (mTNBC). We estimated the risk of progression to treatment-related myeloid neoplasms (t-MN) according to the clonal hematopoiesis risk score (CHRS). In exploratory analyses, we considered clonal hematopoiesis (CH) with variant allele fraction (VAF) ≥0.005. RESULTS: CHIP was identified in 15% of patients before treatment. Few CHIP emerged after treatment, and the risk of developing new mutations was similar for patients receiving CT versus ET (odds ratio [OR], 1.16; P = .820). However, CT increased the risk of developing new CH with VAF ≥0.005 (OR, 3.45; P = .002). Five TP53-mutant CH with VAF ≥0.005 emerged among patients receiving CT. Most patients had low risk of t-MN according to the CHRS score. CHIP did not correlate with survival in mTNBC. CONCLUSION: CHIP is frequent in patients with breast cancer. In this study, CT did not lead to emergence of new CHIP, and most patients had low risk of developing t-MN. This finding is reassuring, given long life expectancy of patients with eBC and the association of CHIP with morbidity and mortality. However, TP53-mutant CH with VAF ≥0.005 emerged with CT, which carries high risk of t-MN. Evolution of these small clones and their clinical significance warrant further investigation.

Association of Somatic TET2 Mutations With Giant Cell Arteritis.

OBJECTIVE: Giant cell arteritis (GCA) is an age-related vasculitis. Prior studies have identified an association between GCA and hematologic malignancies (HMs). How the presence of somatic mutations that drive the development of HMs, or clonal hematopoiesis (CH), may influence clinical outcomes in GCA is not well understood. METHODS: To examine an association between CH and GCA, we analyzed sequenced exomes of 470,960 UK Biobank (UKB) participants for the presence of CH and used multivariable Cox regression. To examine the clinical phenotype of GCA in patients with and without somatic mutations across the spectrum of CH to HM, we performed targeted sequencing of blood samples and electronic health record review on 114 patients with GCA seen at our institution. We then examined associations between specific clonal mutations and GCA disease manifestations. RESULTS: UKB participants with CH had a 1.48-fold increased risk of incident GCA compared to UKB participants without CH. GCA risk was highest among individuals with cytopenia (hazard ratio [HR] 2.98, P = 0.00178) and with TET2 mutation (HR 2.02, P = 0.00116). Mutations were detected in 27.2% of our institutional GCA cohort, three of whom had HM at GCA diagnosis. TET2 mutations were associated with vision loss in patients with GCA (odds ratio 4.33, P = 0.047). CONCLUSIONS: CH increases risk for development of GCA in a genotype-specific manner, with the greatest risk being conferred by the presence of mutations in TET2. Somatic TET2 mutations likewise increase the risk of GCA-associated vision loss. Integration of somatic genetic testing in GCA diagnostics may be warranted in the future.

Acute Lymphoblastic Leukemia with Myeloid Mutations Is a High-Risk Disease Associated with Clonal Hematopoiesis.

Myeloid neoplasms arise from preexisting clonal hematopoiesis (CH); however, the role of CH in the pathogenesis of acute lymphoblastic leukemia (ALL) is unknown. We found that 18% of adult ALL cases harbored TP53, and 16% had myeloid CH-associated gene mutations. ALL with myeloid mutations (MyM) had distinct genetic and clinical characteristics, associated with inferior survival. By using single-cell proteogenomic analysis, we demonstrated that myeloid mutations were present years before the diagnosis of ALL, and a subset of these clones expanded over time to manifest as dominant clones in ALL. Single-cell RNA sequencing revealed upregulation of genes associated with cell survival and resistance to apoptosis in B-ALL with MyM, which responds better to newer immunotherapeutic approaches. These findings define ALL with MyM as a high-risk disease that can arise from antecedent CH and offer new mechanistic insights to develop better therapeutic and preventative strategies. SIGNIFICANCE: CH is a precursor lesion for lymphoblastic leukemogenesis. ALL with MyM has distinct genetic and clinical characteristics, associated with adverse survival outcomes after chemotherapy. CH can precede ALL years before diagnosis, and ALL with MyM is enriched with activated T cells that respond to immunotherapies such as blinatumomab. See related commentary by Iacobucci, p. 142.

SRCAP mutations drive clonal hematopoiesis through epigenetic and DNA repair dysregulation.

Somatic mutations accumulate in all cells with age and can confer a selective advantage, leading to clonal expansion over time. In hematopoietic cells, mutations in a subset of genes regulating DNA repair or epigenetics frequently lead to clonal hematopoiesis (CH). Here, we describe the context and mechanisms that lead to enrichment of hematopoietic stem cells (HSCs) with mutations in SRCAP, which encodes a chromatin remodeler that also influences DNA repair. We show that SRCAP mutations confer a selective advantage in human cells and in mice upon treatment with the anthracycline-class chemotherapeutic doxorubicin and bone marrow transplantation. Furthermore, Srcap mutations lead to a lymphoid-biased expansion, driven by loss of SRCAP-regulated H2A.Z deposition and increased DNA repair. Altogether, we demonstrate that SRCAP operates at the intersection of multiple pathways in stem and progenitor cells, offering a new perspective on the functional impact of genetic variants that promote stem cell competition in the hematopoietic system.

PPM1D modulates hematopoietic cell fitness and response to DNA damage and is a therapeutic target in myeloid malignancy.

PPM1D encodes a phosphatase that is recurrently activated across cancer, most notably in therapy-related myeloid neoplasms. However, the function of PPM1D in hematopoiesis and its contribution to tumor cell growth remain incompletely understood. Using conditional mouse models, we uncover a central role for Ppm1d in hematopoiesis and validate its potential as a therapeutic target. We find that Ppm1d regulates the competitive fitness and self-renewal of hematopoietic stem cells (HSCs) with and without exogenous genotoxic stresses. We also show that although Ppm1d activation confers cellular resistance to cytotoxic therapy, it does so to a lesser degree than p53 loss, informing the clonal competition phenotypes often observed in human studies. Notably, loss of Ppm1d sensitizes leukemias to cytotoxic therapies in vitro and in vivo, even in the absence of a Ppm1d mutation. Vulnerability to PPM1D inhibition is observed across many cancer types and dependent on p53 activity. Importantly, organism-wide loss of Ppm1d in adult mice is well tolerated, supporting the tolerability of pharmacologically targeting PPM1D. Our data link PPM1D gain-of-function mutations to the clonal expansion of HSCs, inform human genetic observations, and support the therapeutic targeting of PPM1D in cancer.

Allogeneic Hematopoietic Cell Transplantation Improves Outcome in Myelodysplastic Syndrome Across High-Risk Genetic Subgroups: Genetic Analysis of the Blood and Marrow Transplant Clinical Trials Network 1102 Study.

PURPOSE: Allogeneic hematopoietic cell transplantation (HCT) in patients with myelodysplastic syndrome (MDS) improves overall survival (OS). We evaluated the impact of MDS genetics on the benefit of HCT in a biological assignment (donor v no donor) study. METHODS: We performed targeted sequencing in 309 patients age 50-75 years with International Prognostic Scoring System (IPSS) intermediate-2 or high-risk MDS, enrolled in the Blood and Marrow Transplant Clinical Trials Network 1102 study and assessed the association of gene mutations with OS. Patients with TP53 mutations were classified as TP53multihit if two alleles were altered (via point mutation, deletion, or copy-neutral loss of heterozygosity). RESULTS: The distribution of gene mutations was similar in the donor and no donor arms, with TP53 (28% v 29%; P = .89), ASXL1 (23% v 29%; P = .37), and SRSF2 (16% v 16%; P = .99) being most common. OS in patients with a TP53 mutation was worse compared with patients without TP53 mutation (21% ± 5% [SE] v 52% ± 4% at 3 years; P < .001). Among those with a TP53 mutation, OS was similar between TP53single versus TP53multihit (22% ± 8% v 20% ± 6% at 3 years; P = .31). Considering HCT as a time-dependent covariate, patients with a TP53 mutation who underwent HCT had improved OS compared with non-HCT treatment (OS at 3 years: 23% ± 7% v 11% ± 7%; P = .04), associated with a hazard ratio of 3.89; 95% CI, 1.87 to 8.12; P < .001 after adjustment for covariates. OS among patients with molecular IPSS (IPSS-M) very high risk without a TP53 mutation was significantly improved if they had a donor (68% ± 10% v 0% ± 12% at 3 years; P = .001). CONCLUSION: HCT improved OS compared with non-HCT treatment in patients with TP53 mutations irrespective of TP53 allelic status. Patients with IPSS-M very high risk without a TP53 mutation had favorable outcomes when a donor was available.

Genetic modification of inflammation- and clonal hematopoiesis-associated cardiovascular risk.

Clonal hematopoiesis of indeterminate potential (CHIP) is associated with an increased risk of cardiovascular diseases (CVDs), putatively via inflammasome activation. We pursued an inflammatory gene modifier scan for CHIP-associated CVD risk among 424,651 UK Biobank participants. We identified CHIP using whole-exome sequencing data of blood DNA and modeled as a composite, considering all driver genes together, as well as separately for common drivers (DNMT3A, TET2, ASXL1, and JAK2). We developed predicted gene expression scores for 26 inflammasome-related genes and assessed how they modify CHIP-associated CVD risk. We identified IL1RAP as a potential key molecule for CHIP-associated CVD risk across genes and increased AIM2 gene expression leading to heightened JAK2- and ASXL1-associated CVD risk. We show that CRISPR-induced Asxl1-mutated murine macrophages had a particularly heightened inflammatory response to AIM2 agonism, associated with an increased DNA damage response, as well as increased IL-10 secretion, mirroring a CVD-protective effect of IL10 expression in ASXL1 CHIP. Our study supports the role of inflammasomes in CHIP-associated CVD and provides evidence to support gene-specific strategies to address CHIP-associated CVD risk.

Prediction of risk for myeloid malignancy in clonal hematopoiesis.

Background: Clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS) are defined by somatic mutations in genes associated with myeloid neoplasms (MN) at a variant allele fraction (VAF) ≥ 0.02, in the absence and presence of cytopenia, respectively. CHIP/CCUS is highly prevalent in adults and defining predictors of MN risk would aid clinical management and research. Methods: We analyzed sequenced exomes of healthy UK Biobank (UKB) participants (n = 438,890) in separate derivation and validation cohorts. Genetic mutations, laboratory values, and MN outcomes were used in conditional probability-based recursive partitioning and Cox regression to determine predictors of incident MN. Combined statistical weights defined a clonal hematopoiesis risk score (CHRS). Independent CHIP/CCUS patient cohorts were used to test prognostic capability of the CHRS in the clinical setting. Results: Recursive partitioning distinguished CHIP/CCUS cases with 10-year probabilities of MN ranging from 0.0078 - 0.85. Multivariable analysis validated partitioning variables as predictors of MN. Key features, including single DNMT3A mutations, high risk mutations, ≥ 2 mutations, VAF ≥ 0.2, age ≥ 65 years, CCUS vs CHIP and red blood cell indices, influenced MN risk in variable direction. The CHRS defined low risk (n = 10018, 88.4%), intermediate risk (n = 1196, 10.5%), and high risk (n = 123, 1.1%) groups. In clinical cohorts, most MN events occurred in high risk CHIP/CCUS patients. Conclusions: The CHRS provides simple prognostic framework for CHIP/CCUS, distinguishing a high risk minority from the majority of CHIP/CCUS which has minimal risk for progression to MN.

Clonal Hematopoiesis in Young Women Treated for Breast Cancer.

PURPOSE: Young women treated for breast cancer with cytotoxic therapies are at risk for clonal hematopoiesis of indeterminate potential (CHIP), a condition in which blood cells carrying a somatic mutation associated with hematologic malignancy comprise at least 4% of the total blood system. CHIP has primarily been studied in older patient cohorts with limited clinical phenotyping. EXPERIMENTAL DESIGN: We performed targeted sequencing on longitudinal blood samples to characterize the clonal hematopoietic landscape of 878 women treated for breast cancer enrolled in the prospective Young Women's Breast Cancer Study. RESULTS: We identified somatic driver mutations in 252 study subjects (28.7%), but only 24 (2.7%) had clones large enough to meet criteria for CHIP. The most commonly mutated genes were DNMT3A and TET2, similar to mutations observed in noncancer cohorts. At 9-year median follow-up, we found no association between the presence of a somatic blood mutation (regardless of clone size) and adverse breast cancer (distant relapse-free survival) or non-breast cancer-related outcomes in this cohort. A subset of paired blood samples obtained over 4 years showed no evidence of mutant clonal expansion, regardless of genotype. Finally, we identified a subset of patients with likely germline mutations in genes known to contribute to inherited cancer risk, such as TP53 and ATM. CONCLUSIONS: Our data show that for young women with early-stage breast cancer, CHIP is uncommon after cytotoxic exposure, is unlikely to contribute to adverse outcomes over the decade-long follow-up and may not require additional monitoring if discovered incidentally.

Clonal haematopoiesis and risk of chronic liver disease.

Chronic liver disease is a major public health burden worldwide1. Although different aetiologies and mechanisms of liver injury exist, progression of chronic liver disease follows a common pathway of liver inflammation, injury and fibrosis2. Here we examined the association between clonal haematopoiesis of indeterminate potential (CHIP) and chronic liver disease in 214,563 individuals from 4 independent cohorts with whole-exome sequencing data (Framingham Heart Study, Atherosclerosis Risk in Communities Study, UK Biobank and Mass General Brigham Biobank). CHIP was associated with an increased risk of prevalent and incident chronic liver disease (odds ratio = 2.01, 95% confidence interval (95% CI) [1.46, 2.79]; P < 0.001). Individuals with CHIP were more likely to demonstrate liver inflammation and fibrosis detectable by magnetic resonance imaging compared to those without CHIP (odds ratio = 1.74, 95% CI [1.16, 2.60]; P = 0.007). To assess potential causality, Mendelian randomization analyses showed that genetic predisposition to CHIP was associated with a greater risk of chronic liver disease (odds ratio = 2.37, 95% CI [1.57, 3.6]; P < 0.001). In a dietary model of non-alcoholic steatohepatitis, mice transplanted with Tet2-deficient haematopoietic cells demonstrated more severe liver inflammation and fibrosis. These effects were mediated by the NLRP3 inflammasome and increased levels of expression of downstream inflammatory cytokines in Tet2-deficient macrophages. In summary, clonal haematopoiesis is associated with an elevated risk of liver inflammation and chronic liver disease progression through an aberrant inflammatory response.

Clonal hematopoiesis in older patients with breast cancer receiving chemotherapy.

BACKGROUND: The expansion of hematopoietic stem cells carrying recurrent somatic mutations, termed clonal hematopoiesis (CH), is common in elderly individuals and is associated with increased risk of myeloid malignancy and all-cause mortality. Though chemotherapy is a known risk factor for developing CH, how myelosuppressive therapies affect the short-term dynamics of CH remains incompletely understood. Most studies have been limited by retrospective design, heterogeneous patient populations, varied techniques to identifying CH, and analysis of single timepoints. METHODS: We examined serial samples from 40 older women with triple-negative or hormone receptor-positive breast cancer treated on the prospective ADjuVANt Chemotherapy in the Elderly trial to evaluate the prevalence and dynamics of CH at baseline and throughout chemotherapy (6 and 12 weeks). RESULTS: CH was detected in 44% of patients at baseline and in 53% at any timepoint. Baseline patient characteristics were not associated with CH. Over the course of treatment, mutations exhibited a variety of dynamics, including emergence, expansion, contraction, and disappearance. All mutations in TP53 (n = 3) and PPM1D (n = 4), genes that regulate the DNA damage response, either became detectable or expanded over the course of treatment. Neutropenia was more common in patients with CH, particularly when the mutations became detectable during treatment, and CH was significantly associated with cyclophosphamide dose reductions and holds (P = .02). CONCLUSIONS: Our study shows that CH is common, dynamic, and of potential clinical significance in this population. Our results should stimulate larger efforts to understand the biological and clinical importance of CH in solid tumor malignancies. TRIAL REGISTRATION: ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT03858322). Clinical trial registration number: NCT03858322.

TP53-mediated clonal hematopoiesis confers increased risk for incident atherosclerotic disease.

Somatic mutations in blood indicative of clonal hematopoiesis of indeterminate potential (CHIP) are associated with an increased risk of hematologic malignancy, coronary artery disease, and all-cause mortality. Here we analyze the relation between CHIP status and incident peripheral artery disease (PAD) and atherosclerosis, using whole-exome sequencing and clinical data from the UK Biobank and Mass General Brigham Biobank. CHIP associated with incident PAD and atherosclerotic disease across multiple beds, with increased risk among individuals with CHIP driven by mutation in DNA Damage Repair (DDR) genes such as TP53 and PPM1D. To model the effects of DDR-induced CHIP on atherosclerosis, we used a competitive bone marrow transplantation strategy, and generated atherosclerosis-prone Ldlr-/- chimeric mice carrying 20% p53-deficient hematopoietic cells. The chimeric mice were analyzed 13-weeks post-grafting and showed increased aortic plaque size and accumulation of macrophages within the plaque, driven by increased proliferation of p53-deficient plaque macrophages. In summary, our findings highlight the role of CHIP as a broad driver of atherosclerosis across the entire arterial system beyond the coronary arteries, and provide genetic and experimental support for a direct causal contribution of TP53-mutant CHIP to atherosclerosis.

'ADVANCE' (a pilot trial) ADjuVANt chemotherapy in the elderly: Developing and evaluating lower-toxicity chemotherapy options for older patients with breast cancer.

INTRODUCTION: Older adults with breast cancer receiving neo/adjuvant chemotherapy are at high risk for poor outcomes and are underrepresented in clinical trials. The ADVANCE (ADjuVANt Chemotherapy in the Elderly) trial evaluated the feasibility of two neo/adjuvant chemotherapy regimens in parallel-enrolling cohorts of older patients with human epidermal growth factor receptor 2-negative breast cancer: cohort 1-triple-negative; cohort 2-hormone receptor-positive. MATERIALS AND METHODS: Adults age ≥ 70 years with stage I-III breast cancer warranting neo/adjuvant chemotherapy were enrolled. Cohort 1 received weekly carboplatin (area under the curve 2) and weekly paclitaxel 80 mg/m2 for twelve weeks; cohort 2 received weekly paclitaxel 80 mg/m2 plus every-three-weekly cyclophosphamide 600 mg/m2 over twelve weeks. The primary study endpoint was feasibility, defined as ≥80% of patients receiving ≥80% of intended weeks/doses of therapy. All dose modifications were applied per clinician discretion. RESULTS: Forty women (n = 20 per cohort) were enrolled from March 25, 2019 through August 3, 2020 from three centers; 45% and 35% of patients in cohorts 1 and 2 were age > 75, respectively. Neither cohort achieved targeted thresholds for feasibility. In cohort 1, eight (40.0%) met feasibility (95% confidence interval [CI] = 19.1-63.9%), while ten (50.0%) met feasibility in cohort 2 (95% CI = 27.2-72.8). Neutropenia was the most common grade 3-4 toxicity (cohort 1-65%, cohort 2-55%). In cohort 1, 80% and 85% required ≥1 dose holds of carboplatin and/or paclitaxel, respectively. In cohort 2, 10% required dose hold(s) for cyclophosphamide and/or 65% for paclitaxel. DISCUSSION: In this pragmatic pilot examining chemotherapy regimens in older adults with breast cancer, neither regimen met target goals for feasibility. Developing efficacious and tolerable regimens for older patients with breast cancer who need chemotherapy remains an important goal. CLINICALTRIALS: gov Identifier: NCT03858322.

Patient perspectives on testing for clonal hematopoiesis of indeterminate potential.

Clonal hematopoiesis of indeterminate potential (CHIP), an emerging biomarker for personalized risk-directed interventions, is increased in cancer survivors. However, little is known about patient preferences for CHIP testing. We surveyed participants in a prospective cohort study of young women with breast cancer (BC). The emailed survey included an introduction to CHIP and a vignette eliciting participants' preferences for CHIP testing, considering sequentially: population-based 10-year risk of BC recurrence, hematologic malignancy, and heart disease; increased CHIP-associated risks; current CHIP management; dedicated CHIP clinic; and hypothetical CHIP treatment. Preference changes were evaluated using the McNemar test. The survey response rate was 82.2% (528/642). Median age at time of survey was 46 years and median time from diagnosis was 108 months. Only 5.9% had prior knowledge of CHIP. After vignette presentation, most survivors (87.1%) recommended CHIP testing for the vignette patient. Presented next with CHIP-independent, population-based risks, 11.1% shifted their preference from testing to not testing. After receiving information about CHIP-associated risks, an additional 10.1% shifted their preference to testing. Preference for testing increased if vignette patient was offered a CHIP clinic or hypothetical CHIP treatment, with 7.2% and 14.1% switching preferences toward testing, respectively. Finally, 75.8% of participants desired CHIP testing for themselves. Among participants, 28.2% reported that learning about CHIP caused at least moderate anxiety. Most young survivors favored CHIP testing, with preferences influenced by risk presentation and potential management strategies. Our findings highlight the importance of risk communication and psychosocial support when considering biomarkers for future risk in cancer survivors. This trial has been registered at www.clinicaltrials.gov as #NCT01468246.