A framework for the molecular identification of CHIP for clinical research.

7010 Background: Clonal hematopoiesis (CH) of indeterminate potential (CHIP) is found in healthy populations as well as cancer patients (pts) and is associated with (w/) cardiovascular disease (CVD), risk of hematologic neoplasms (HN), and all-cause mortality. Germline variants (var) predispose to CHIP. However, described var are nonspecific to solid tumor pts. Identifying CHIP risk factors and mitigation strategies is paramount for improving outcomes. Methods: Pts in breast (BC) and head & neck cancer (HNC) survivorship (2020-2023) following curative treatment (tx) were eligible for our 10 year (yr) prospective study of annual next generation sequencing (NGS) and complete blood count (CBC) to identify CHIP. Mutations (mt) were classified as clinically significant (CS) or var of unknown significance (VUS), and as CH (med. VAF 4.7%) or potentially germline (PG; med. VAF 50%). Pts w/ CHIP were managed in both CHIP Clinic (CC) and Preventive Cardiology (PC) for monitoring and CVD reduction. Fisher’s exact and ANOVA tests were used for analyses. Results: Of 168 pts enrolled (117 BC, 51 HNC), 158 had NGS: 73 yr 1, 85 through yr 2 or 3; 22 pts received chemotherapy (CT), 49 radiation therapy (RT), 72 CT & RT (CRT). Sixty-eight pts (43%) had a mt; 21 (13%) had CHIP (6 w/ PG VUS). CHIP was found to be associated w/ older age (69 vs. 58, p= 0.0002). The most common CHIP mt were DNMT3A (n = 11), PPM1D (6), TET2 (6), JAK2 a nd TP53 (2). Two pts without yr 1 mt developed CHIP in yr 2. For PPM1D, 2 PG VUS were point mt from DNA transitions while 6 CHIP were truncating from transversions and deletions. All pts w/ PPM1D had RT (7/8 CRT), suggesting a molecular signature which varies from transition-driven aging. Six pts had thrombocytopenia (TP), 3 w/ PPM1D CHIP. TP was more common in CHIP (OR 11, p= 0.0356) and PPM1D (OR 29, p= 0.0016). In this cohort, anemia was not seen in pts w/ CHIP ( p= 0.048). Normal CBC was 6x less common in pts w/ CRT ( p= 2.3x10-7). Seven CHIP pts were seen by PC; 4 had yr 2 NGS following PC visit. All pts had addition of new/dose escalation of current CVD medication. Two CHIP pts had stable NGS; 2 CHIP & PG VUS pts had clonal changes including mt disappearance and acquisition. Of note, the PG VUS’s were assessed for institutional incidence in 3,918 HN pts w/ NGS data and in Mastermind (MM) for frequency of occurrence in published literature. Sixteen PG VUS (40%) occurred at our institution (13 found in MM, 7 classified as rare (avg gnomAD MAF 6x10-4)) and associated w/ HN, notably TET2 (n = 3). Conclusions: This ongoing prospective study is one of the largest to report characteristics and outcomes of CHIP pts in CC/PC and is expected to accrue more in expansion. We anticipate highlighting risk factors for CHIP progression and report novel PG VUS, which may portend health risks based on their prevalence in HN. Furthermore, it appears that a strategy for CVD prevention may promote clonal stability in survivorship pts.

Clonal hematopoiesis of indeterminate potential (CHIP) is defined by the age-dependent accumulation of somatic leukemia-associated driver mutations in hematopoietic stem cells, in individuals with normal blood counts and with absence of an underlying myeloid neoplasm (MN).1, 2 CHIP is associated with an increased risk of developing MN and an increased all-cause mortality, largely due to cardiovascular disease.3 The presence of CHIP prior to receiving chemotherapy and radiation has been associated with therapy related MN (T-MN), such as myelodysplastic syndromes (MDS) and acute myeloid leukemia.4 Autologous stem cell transplantation (ASCT) is an effective treatment modality for managing higher-risk patients with non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM). In a seminal NHL study, 30% of patients were found to have CHIP at the time of ASCT, with the presence of CHIP being associated with an increased rate of T-MN (10-year cumulative incidence of 14.1% vs 4.3%) and an inferior overall survival (10 year OS 30.4% vs 60.9%).5 In MM, targeted sequencing of 629 patients prior to ASCT detected CHIP in 21.6% of patients, with the presence of CHIP strongly associating with inferior OS (HR 1.34, p = .02) and an inferior progression-free survival (PFS, HR 1.45, p < .001). Interestingly, in this study, adverse CHIP-associations were apparently overcome by lenalidomide maintenance therapy.6 Unlike in NHL, CHIP in MM was not associated with T-MN; while lenalidomide maintenance therapy, independent of the presence or absence of CHIP, was associated with T-MN (p = .047) and second primary malignancies (SPM).6 We carried out this study to assess the prevalence and prognostic impact of CHIP in a relatively uniform cohort of MM patients at the time of ASCT, with all patients going on to receive lenalidomide maintenance therapy. Successive MM patients who consented to have their pre-ASCT bone marrow (BM) sample collected and who underwent first ASCT at Mayo Clinic, followed by lenalidomide maintenance therapy, were included in the study. The BM mononuclear cell DNA from pre-ASCT samples was extracted after excluding CD38/CD138+ (negative selection) plasma cells and then subjected to targeted NGS testing (42-myeloid related genes) by previously described methods.7 All patients were closely followed for the development of T-MN as defined by the 2016 WHO criteria, arterial and venous thromboembolism (VTE) and SPM.8, 9 Response to therapy was assessed using the international myeloma working group (IMWG) consensus criteria 2016.10 Statistical methods are highlighted in the supplemental material. Clonal hematopoiesis was detectable in 23 (23%) of 101 MM patients assessed in the study (Table S1, Figure S1). Clinical characteristics, MM risk stratification, median number of prior therapies, response to therapy, ASCT conditioning regimens, engraftment data, day +100 post ASCT outcomes and median duration of lenalidomide maintenance are outlined in Table 1. Except for a higher median age at MM diagnosis in MM patient with CHIP (p = .002), there were no other significant differences between the two groups (Figure S2). Ten (43.5%) patients in the MM CHIP group and 30 (38.0%) in the MM no CHIP group, received alkylatingagent-based induction therapy prior to ASCT (p = .66). Melphalan 200 mg/m2 conditioning was used in 87.1% of patients (95.7% in the CHIP vs 84.6% in the no CHIP group, p = .45), while the remainder received melphalan 140 mg/m2 conditioning. The median duration of lenalidomide maintenance therapy was 21 months (10–36); 16 months in MM patients with CHIP and 22 months in MM patients without CHIP (p = .76), with the median lenalidomide dose being 15 mg (range 10–15 mg; 10 mg in the CHIP group and 15 mg in the no CHIP group, p = .08). The most frequent CHIP mutations encountered included DNMT3A [52%; median variant allele frequency (VAF) 9.0%, range 2.0%–29.2%], TET2 (26%; median VAF 3.0%, range 2.0%–4.8%), followed by TP53, PPM1D and BRAF (10.0% each), respectively (Figures 1(A) and S1). Sixteen patients (69.6%) had one mutation, while seven (30.4%) had >1 mutation and two patients had four mutations each (Figure 1(B)). Eight (66.6%) of 12 patients with DNMT3A mutations had nonsynonymous missense mutations, while four had deletion variants: with no patient harboring the commonly mutated DNMT3A R882 hot spot. There were no statistically significant differences in CHIP mutation distribution, including TP53 and PPM1D mutations, between MM CHIP patients that received alkylating-agent based induction therapy prior to ASCT, vs MM CHIP patients that did not (Figure 1(C)). At last follow up, 70 (69.3%) relapses after ASCT and 41 (40.6%) deaths were documented. Twenty-nine patients (28.7%) were on salvage therapy whereas 13 (12.9%) were on lenalidomide maintenance and 14 (13.8%) were on observation alone, with no statistically significant differences between MM patients with CHIP vs MM without CHIP. Rates of VTE were similar between MM patients with CHIP (30%) and those without CHIP (24%), with similar rates of provoked thromboses (33% vs 29%, p = .4). Thromboses were diagnosed in typical locations in individuals with CHIP including seven lower extremity deep vein thromboses (DVT) and two pulmonary emboli (PE). In contrast, a variety of VTE locations were diagnosed in those without CHIP, including 10 lower extremity DVT, three PE, one DVT with PE, two upper extremity DVT and one portal vein thrombosis. There was a distinction in VTE timing with regards to lenalidomide use between MM patients with CHIP and those without CHIP. For MM patients with CHIP, 2/9 (22.2%) VTE occurred while on lenalidomide, 2/9 (22.2%) occurred prior to lenalidomide and 4/9 (44.4%) occurred at least 3 months after discontinuation of lenalidomide therapy. For MM patients without CHIP, majority (13/17, 76.5%) of VTE occurred while on lenalidomide, with a minority (11%) occurring either before or at least 3 months after discontinuation of lenalidomide. While lenalidomide is a known risk factor for thrombosis in MM, the fact that 44% of VTE in MM with CHIP occurred >3 months after discontinuing lenalidomide, suggests that CHIP might increase VTE risk in this setting (P = .04). Median OS from the time of diagnosis of the entire cohort was 124.6 months (95%CI 97.5-N/A months) with a corresponding 5 year OS of 82.0% (95% CI 74.8%–89.9%). There was no difference in median OS between MM with CHIP vs those without CHIP (100.2 months; 95%CI 76.2-NA months vs 135.6 months; 95%CI 106.3-N/A months, p = .27) (Figure 1(D)), including assessments with individual CHIP-mutations. The median EFS after ASCT was 36.4 months (95%CI 30.5–48.5 months), with there being no difference in median PFS between MM CHIP (36.4 months, 95%CI 24.1–58.5 months) patients vs MM patients without CHIP (36.4 months, 95%CI 29.9–52.4 months) (p = .34) (Figure 1(E)), including TP53 mutations (Figure S3). There were also no differences between the two groups with regards to non-relapse mortality (Figure S4), cumulative incidence of relapse after ASCT (Figure S5) and time to next treatment. Nineteen (18.8%) SPM were documented, 7 (30.4%) in MM CHIP group vs 12 (15.3%) in the MM no CHIP group (Figure 1(F), p = .13), with corresponding 5-year cumulative incidence rates of 22% and 13%, respectively. These SPM included five (4.9%) hematological malignancies (two in MM CHIP vs three in MM no CHIP), seven (6.9%) skin cancers (three in MM CHIP vs four in MM no CHIP) and seven visceral malignancies (two in MM CHIP vs five in MM no CHIP) (Table S2, Figure S6). The two MM CHIP patients who developed T-MN/MDS had TP53 and PPM1D mutations, respectively. In the MM no CHIP group, there was one patient with B-acute lymphoblastic leukemia and two patients with T-MDS with monosomal karyotypes. In summary, we define the CHIP landscape in MM patients at the time of ASCT, with mutations in epigenetic regulator genes being most common (57%), followed by tumor suppressor genes (17%). Unlike in NHL, presence of CHIP at time of ASCT in MM did not impact OS, PFS and incidence of T-MN; a finding potentially attributable to immunomodulatory properties of lenalidomide, or to the use of maintenance therapy in general.6, 11 While the presence of CHIP and lenalidomide therapy have individually been associated with increased risk of thromboses,1-3, 9 we did not see synergy in MM patients with CHIP, although the timing and patterns of thromboses suggest that CHIP might negatively influence thrombotic risk. While SPM have been well described with lenalidomide maintenance therapy,9 we did not see any differences in SPM and hematological malignancies between the two groups. The findings of this study independently confirm a prior observation on the potential ability of lenalidomide maintenance to mitigate the expected adverse effects of CHIP on OS and PFS in MM patients' post-ASCT6; an important consideration given that approximately 13 000 MM patients undergo ASCT in the US annually, with lenalidomide maintenance considered as standard of care.12, 13 Given the smaller sample size and the inherent flaws of a retrospective analysis, future clinical trials evaluating therapies in MM patients' post-ASCT should consider accounting for the presence of CHIP and its impact on outcomes. The authors would like to acknowledge the “Henry Predolin Leukemia Foundation”, Mayo Clinic, Rochester, MN, USA. Mrinal Patnaik has served on the advisory board of Kura Oncology. A Keith Stewart has served on the advisory board for Celgene. Rafael Fonseca has the following disclosures: Consulting: Amgen, BMS, Celgene, Takeda, Bayer, Janssen, Novartis, Pharmacyclics, Sanofi, Karyopharm, Merck, Juno, Kite, Aduro, OncoTracker, Oncopeptides, GSK, AbbVie. Scientific Advisory Board: Adaptive Biotechnologies, Caris Life Sciences and OncoTracker. Gene mutations annotated in the study have been provided in the supplementary material. Raw sequencing data can be made available on request. Appendix S1 Supporting Information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Clonal hematopoiesis (CH) of indeterminate potential (CHIP), driven by somatic mutations in leukemia-associated genes, confers increased risk of hematologic malignancies, cardiovascular disease, and all-cause mortality. In blood of healthy individuals, small CH clones can expand over time to reach 2% variant allele frequency (VAF), the current threshold for CHIP. Nevertheless, reliable detection of low-VAF CHIP mutations is challenging, often relying on deep targeted sequencing. Here, we present UNISOM, a streamlined workflow for enhancing CHIP detection from whole-genome and whole-exome sequencing data that are underpowered, especially for low VAFs. UNISOM utilizes a meta-caller for variant detection, in couple with machine learning models which classify variants into CHIP, germline, and artifact. In whole-exome sequencing data, UNISOM recovered nearly 80% of the CHIP mutations identified via deep targeted sequencing in the same cohort. Applied to whole-genome sequencing data from Mayo Clinic Biobank, it recapitulated the patterns previously established in much larger cohorts, including the most frequently mutated CHIP genes and predominant mutation types and signatures, as well as strong associations of CHIP with age and smoking status. Notably, 30% of the identified CHIP mutations had < 5% VAFs, demonstrating its high sensitivity toward small mutant clones. This workflow is applicable to CHIP screening in population genomic studies. The UNISOM pipeline is freely available at https://github.com/shulanmayo/UNISOM and https://ngdc.cncb.ac.cn/biocode/tool/7816.

Introduction: Clonal hematopoiesis of indeterminate potential (CHIP) is an age-related disorder associated with increased risk of atherosclerotic cardiovascular disease (ASCVD). Mechanistic studies of CHIP implicate inflammatory pathways underlying this relationship. Although inflammation is a well-established component of chronic kidney disease (CKD), linked to both CKD progression and ASCVD in CKD patients, CHIP has not been investigated in a CKD setting. Objective: To estimate the prevalence of CHIP in patients with CKD and to examine the cross-sectional associations between CHIP and biomarkers that were previously related to CKD progression and ASCVD among CKD patients. Methods: The current study was conducted among 598 Chronic Renal Insufficiency Cohort (CRIC) study participants with whole-exome sequencing data and baseline measures of fibrinogen, interleukin (IL)-6, serum albumin, and tumor necrosis factor-α. CHIP was detected from sequencing data using MuTect2. CHIP was defined as the presence of a somatic hematologic malignancy-associated mutation with a variant allele frequency (VAF) of at least 2%. CHIP was also categorized ordinally by clone size as no CHIP, small CHIP clone (VAF&lt;10%), and large CHIP clone (VAF ≥10%). Ordinal logistic regression was used to test associations of CHIP with each biomarker in age- and multivariable-adjusted models. Multivariable models adjusted for age, sex, ancestry, body mass index, estimated glomerular filtration rate, systolic blood pressure, low-density lipoprotein cholesterol, fasting plasma glucose, and blood pressure, lipid, and glucose lowering medications. Results: CHIP was detected in a total of 28 individuals from the WES study (4.7%). Among those 70 years of age and older, we detected a CHIP prevalence of nearly 16%. As expected, participants with CHIP were older than those without CHIP (mean age: 67 and 58 years, respectively; P&lt;0.0001). Other demographic and clinical variables were similar between groups . Age-adjusted models showed strong associations between CHIP and both fibrinogen and IL-6 with odds ratios of 2.49 (95% CI: 1.09, 5.71) and 2.45 (95% CI: 1.05, 5.72), respectively. After multivariable adjustment, only fibrinogen remained associated with CHIP with an odds ratio of 4.70 (95% CI: 1.69, 13.0). Consistent with these findings, there was a strong dose-dependent association between CHIP clone size and fibrinogen in multivariable adjusted analyses (P for linear trend=0.009). Compared to those without CHIP, odds ratios for higher fibrinogen tertile were 3.0 (95% CI: 0.84, 11.3) and 4.7 (95% CI: 1.29, 16.7) among those with small and large CHIP clone sizes, respectively. Conclusions: CHIP prevalence was higher among CKD patients in the current study compared to previous estimates from the general population. Furthermore, a strong, dose-dependent association between CHIP and fibrinogen was identified.

e24108 Background: Clonal hematopoiesis of Indeterminate Potential (CHIP) is associated with adverse clinical outcomes including increased risk of hematologic malignancies and heart disease. Limited data suggest an increased prevalence of CHIP in patients treated for solid tumors, particularly after exposure to radiation and chemotherapy. CHIP testing may inform risk-reduction strategies for cancer survivors. Little is known about patient knowledge, attitudes, and preferences regarding CHIP testing. Methods: We surveyed survivors without history of recurrence participating in an ongoing prospective cohort study of young women with breast cancer (BC). The survey was sent by email and included an introduction to CHIP including risk factors and clinical associations. Respondents then reviewed a vignette and were asked about CHIP testing preferences (definitely/probably test vs. definitely/probably not test) considering sequentially: 1) population-based 10-year risk of BC recurrence, hematological malignancy and heart disease; 2) estimated increase in these risks with CHIP; 3) current CHIP management; 4) a dedicated CHIP clinic; and 5) a theoretical CHIP treatment. Changes in preferences from the prior scenario were evaluated with the McNemar's test using a type I error rate of 5%. Results: 528/642 (82.2%) eligible women responded to the survey, at a median age of 46 (range: 31-54) years (median time from diagnosis: 108 months (range: 60-168)), and 88% were white. Most had stage 1/2 BC (78.8%) and had received chemotherapy (73.1%) and/or radiation (61.9%). 93.6% had never heard of CHIP prior to survey. After initial patient vignette presentation, most women (87.1%,) recommended CHIP testing if offered. Preferences for testing decreased (p&lt;0.05) when considering population-based risks, with 11.1% shifting their preference from CHIP testing to not testing. After considering increased risks associated with CHIP, interest in testing increased (p&lt;0.05), with 10.1% shifting their preference to testing. Interest significantly (p&lt;0.05) increased with the possibility of managing CHIP through a clinic or a hypothetical CHIP treatment, with 7.2% and 14.1% switching their preferences towards testing, respectively. Finally, 75.8% responded that they themselves, after learning about CHIP and reviewing the vignette, would want to have CHIP testing; 28.2% reported that learning about CHIP and the associated risks caused them at least moderate anxiety. Conclusion: Few young BC survivors were aware of CHIP yet most indicated an interest in testing after learning about it. Testing preferences were influenced by risks presented and potential management strategies. Findings highlight the importance of effective risk communication and the need for adequate psychosocial support when considering testing for CHIP and other potential clinical biomarkers predictive of cancer and other medical risks in cancer survivors.

INTRO: Clonal hematopoiesis (CH) of indeterminate potential (CHIP) is associated with poor outcomes in those with non-hematologic cancers. CH mutated macrophages and neutrophils have increased capacity to home to peripheral tissues, driving local inflammation; they are also implicated in immunotherapy related toxicity. The relationship between CH and the microbiome in those treated with immunotherapy is not well understood. RESULTS: 35 patients with stage IV melanoma treated with upfront immunotherapy; treatment and cohort characteristics are below (Table 1). We performed error corrected duplex sequencing on peripheral blood mononuclear cells using a panel previously validated for CH mutations. With a cutoff of 0.5% variant allele frequency (VAF), among 10 CHIP positive patients, we found mutations in TET2 (8/10), DNMT3A (7/10), PPM1D (2/10), and JAK2 (1/10). There was no difference in either survival or response based on CHIP status (Log-Rank Chi-Square p=0.44); however, CHIP positivity was associated with greater microbiome richness as measured by alpha diversity (p=0.0012 Shannon diversity) and distinct structural/compositional diversity vs CHIP negative patients as measured by beta diversity (p=0.032, R Squared= 0.045). We inferred KEGG pathway activity from whole genome sequencing and identified that CHIP positive patients were enriched for exopolysaccharide biosynthesis while CHIP negative patients had higher expression of nucleotide sugars biosynthesis and amino acid metabolism pathways. DISCUSSION: In patients treated with immunotherapy for melanoma, microbiome diversity signatures correlate with presence of CHIP. The analysis suggests that there are distinct taxonomic and functional features defining CHIP positivity. The effect of these cells in the tumor microenvironment and their role in immunotherapy response requires further exploration. Citation Format: Eleanor A. Fallon, Samuel Urrutia, Reed Ayabe, Manoj Chelvanambi, Ashish Damania, Sarah Johnson, Tomoyuki Tanaka, Zongrui Li, Yongwoo David Seo, Samuel Cass, Matthew C. Wong, Nadim Ajami, Jennifer Wargo, Koichi Takahashi. Identifying gut microbial determinants of clonal hematopoiesis of indeterminate potential (CHIP) in immunotherapy treated melanoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2801.

Little is known regarding the potential relationship between clonal hematopoiesis (CH) of indeterminate potential (CHIP), which is the expansion of hematopoietic stem cells with somatic mutations, and risk of prostate cancer, the fifth leading cause of cancer death of men worldwide. We evaluated the association of age-related CHIP with overall and aggressive prostate cancer risk in two large whole-exome sequencing studies of 75 047 European ancestry men, including 7663 prostate cancer cases, 2770 of which had aggressive disease, and 3266 men carrying CHIP variants. We found that CHIP, defined by over 50 CHIP genes individually and in aggregate, was not significantly associated with overall (aggregate HR = 0.93, 95% CI = 0.76-1.13, P = 0.46) or aggressive (aggregate OR = 1.14, 95% CI = 0.92-1.41, P = 0.22) prostate cancer risk. CHIP was weakly associated with genetic risk of overall prostate cancer, measured using a polygenic risk score (OR = 1.05 per unit increase, 95% CI = 1.01-1.10, P = 0.01). CHIP was not significantly associated with carrying pathogenic/likely pathogenic/deleterious variants in DNA repair genes, which have previously been found to be associated with aggressive prostate cancer. While findings from this study suggest that CHIP is likely not a risk factor for prostate cancer, it will be important to investigate other types of CH in association with prostate cancer risk.

Clonal hematopoiesis (CH) of indeterminate potential (CHIP) is a risk factor for cardiovascular disease. The relationship between CHIP and coronary microvascular dysfunction (CMD) is unknown. The current study examines the association between CHIP and CH with CMD and the potential relationships in risk for adverse cardiovascular outcomes. In this retrospective observational study, targeted next-generation sequencing was performed for 177 participants with no coronary artery disease who presented with chest pain and underwent routine coronary functional angiogram. Patients with somatic mutations in leukemia-associated driver genes in hematopoietic stem and progenitor cells were examined; CHIP was considered at a variant allele fraction ≥2%; CH was considered at a variant allele fraction ≥1%. CMD was defined as coronary flow reserve to intracoronary adenosine of ≤2. Major adverse cardiovascular events considered were myocardial infarction, coronary revascularization, or stroke. A total of 177 participants were examined. Mean follow-up was 12±7 years. A total of 17 patients had CHIP and 28 had CH. Cases with CMD (n=19) were compared with controls with no CMD (n=158). Cases were 56±9 years, were 68% women, and had more CHIP (27%; P=0.028) and CH (42%; P=0.001) than controls. CMD was associated with independent risk for major adverse cardiovascular events (hazard ratio, 3.89 [95% CI, 1.21-12.56]; P=0.023), and 32% of this risk was mediated by CH. The risk mediated by CH was ≈0.5× as large as the direct effect of CMD on major adverse cardiovascular events. In humans, we observe patients with CMD are more likely to have CHIP, and nearly one-third of major adverse cardiovascular events in CMD are mediated by CH.

AB0161 CLONAL HEMATOPOIESIS IS INCREASED AND NOT RELATED TO AGING IN SYSTEMIC SCLEROSIS

Clonal hematopoiesis is a proposed marker of aging. Clonal hematopoiesis of indeterminate potential (CHIP) is a candidate risk factor for atherosclerotic cardiovascular diseases, hematological malignancies, and all-cause mortality, while its associations with the diseases of other systems and cause-specific mortality remain inconclusive. We estimated the longitudinal risk for CHIP with 70 common diseases, all-cause, and cause-specific mortality among 431,546 participants in the UK Biobank. Two-sample Mendelian randomization analyses were performed to test the causal associations of CHIP with incident diseases. Cox proportional hazard regression model was used to generate the hazard ratio [HR] and 95% confidence interval [CI] for each CHIP phenotype with the common health-related outcomes. Also evaluated the joint associations between CHIP and telomere length for diseases and mortalities. This study included 431,546 participants (mean age, 56.49years; 45.7% male), of whom 20,274 had CHIP. CHIP at baseline was associated with increased risk of cancers (HR = 1.14, 95% CI 1.10-1.17), infections (HR = 1.12, 95% CI 1.07-1.16), ischemic heart diseases (HR = 1.07, 95% CI 1.02-1.12), diseases of the blood (HR = 1.31, 95% CI 1.26-1.37), nervous (HR = 1.05, 95% CI 1.01-1.10), respiratory (HR = 1.10, 95% CI 1.06-1.13), and genitourinary systems (HR = 1.10, 95% CI 1.07-1.14), and related mortality (false discovery rate<0.05). CHIP carriers were also at elevated risk of incident mental (HR = 1.07, 95% CI 1.03-1.12) and dermatological (HR = 1.07, 95% CI 1.03-1.11) disorders and mortality due to circulatory system (HR = 1.19, 95% CI 1.11-1.28). Most of the associations between CHIP and diseases or mortalities were robust after adjustment for inflammatory parameters. Large clone size CHIP had higher longitudinal risks compared with small clone size or overall CHIP. CHIP due to TET2 mutation was associated with more outcomes than other common CHIP driver genes. Significant interactions were observed between CHIP and short telomere length, the additive and multiplicative effects on the risk of diseases and mortalities were more obvious among large clone size CHIP. This study showed that CHIP was associated with diseases and mortalities of multiple systems, suggesting CHIP was a candidate risk factor for human health.

Clonal Hematopoiesis of Indeterminate Potential Is Associated with Decreased Inflammatory Toxicity and Increased Late Cytopenia in Patients with Multiple Myeloma and Non-Hodgkin Lymphoma Treated with Chimeric Antigen Receptor T-Cell Therapy

Background. Patients (pts) with metastatic triple negative breast cancer (mTNBC) receive serial cytotoxic chemotherapy regimens, often with cumulative myelosuppressive effects, impairing treatment tolerance. Clonal hematopoiesis of indeterminate potential (CHIP) refers to the detection of somatic mutations in genes recurrently mutated in hematologic malignancies in the blood of adults with no evident hematologic abnormalities. Little is known about the natural history of CHIP after breast cancer treatment. We sought to characterize CHIP in pts undergoing treatment for mTNBC. Methods. In this retrospective cohort study we identified 149 pts with biopsy-proven mTNBC at a single tertiary care institution with at least one blood sample collected within six months of metastatic diagnosis. We performed targeted sequencing of cryopreserved peripheral blood mononuclear cell (PBMC)-derived genomic DNA and defined CHIP as the presence of at least one pathogenic somatic mutation present at variant allelic fraction (VAF) of 0.02-0.35. We assessed the relationship between CHIP status and overall survival (OS), demographics, clinicopathologic features, germline mutation status, and type and timing of therapy. Results. We identified 27 unique CHIP variants across 22/149 pts (15%) within six months of metastatic diagnosis. Frequency of mutated genes were as follows: DNMT3A (n=15), PPM1D (n=4), TP53 (n=3), TET2 (n=2), SRCAP (n=1), ZBTB33 (n=1), ZNF318 (n=1). Median follow-up in the cohort was 37.9 months (IQR: 23.9-Not reached). The median age at time of blood draw was 55 years (IQR: 8.5) for pts with CHIP vs. 51 years (IQR: 16.5) for pts without CHIP. Ten (45%) pts with CHIP and 47 (37%) pts without CHIP were current or former smokers. Two (9%) pts with CHIP and 10 (7.9%) pts without CHIP were known germline mutation carriers of BRCA1, BRCA2 or PALB2. Twenty-two (100%) pts with CHIP and 124 (98%) pts without CHIP had received systemic chemotherapy for mTNBC prior to blood draw. There were no significant differences in type of chemotherapy regimen received between patients with or without CHIP. Twenty (90.9%) pts with CHIP vs. 96 (75.6%) of pts without CHIP had received radiation therapy prior to blood draw. Pts with CHIP had similar OS to those without CHIP (median OS 7.75 [2.20-31.7] vs. 9.33 [8.02-11.73] months). No pts developed therapy-related myeloid neoplasms (t-MN) or died of complications of cardiac disease. Conclusions. Pts with mTNBC had a higher frequency of CHIP than previously reported in age-matched healthy populations, but similar CHIP prevalence to what has been seen in cohorts of pts with solid tumors. Our study assessed for the presence of CHIP at only a single time point early in the metastatic course, but serial blood sampling later in treatment might reveal additional cases of CHIP. Though this cohort of patients with life-limiting mTNBC was small, presence of CHIP in the first six months of metastatic diagnosis was not associated with worse survival. Citation Format: Katheryn Santos, Qingchun Jin, Peter G. Miller, Ashka Patel, Gregory J. Kirkner, Janet L. Files, Melissa E. Hughes, Samantha M. Stokes, Nabihah Tayob, Daniel G. Stover, Christopher J. Gibson, Eric P. Winer, Nancy U. Lin, Judy E. Garber, Heather A. Parsons. Clonal hematopoiesis of indeterminate potential (CHIP) in metastatic triple negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-08-01.

Introduction: Clonal hematopoiesis of indeterminate potential (CHIP) has been associated with an increased risk of coronary artery disease (CAD) and cardiovascular (CV) mortality. Whether CHIP may affect myocardium beyond promoting CAD, or its potential association with sudden cardiac death (SCD), the most feared manifestation of CV disease, is unknown. Research Questions/Hypothesis: We hypothesize that CHIP-mutant macrophages infiltrate the myocardium and are associated with autopsy-defined arrhythmic death. Goals/Aims: (1) determine rate of CHIP at time of death in an unselected, countywide study of all incident sudden deaths; (2) evaluate whether CHIP-mutant macrophages infiltrate into myocardium; and (3) evaluate potential association of CHIP with autopsy-confirmed arrhythmic causes among countywide sudden deaths Methods/Approach: We used autopsy to adjudicate arrhythmic from non-arrhythmic (PE, stroke, overdose, tamponade) causes in 1,148 sudden deaths and 141 trauma control deaths in San Francisco County from 2011-23. DNA was extracted from frozen blood samples collected at time of death from 399 consented cases. Sequencing of 22 CHIP-associated genes was performed to ~2000x mean target coverage. All pathogenic/likely pathogenic CHIP variants at &gt;2% variant allele frequency (VAF) were considered CHIP+. DNA was then isolated from left ventricular (LV) tissue sampled at autopsy in all CHIP+ blood cases and sequenced as above. Results: Of 399 consented cases, 70 blood samples (17.5%) were CHIP+ (range 2%-39.6%; mean age 70.6 years vs. 58.1 years for CHIP-). The most frequent mutant genes were DNMT3A, TET2, and ASXL1. Proportion of arrhythmic causes among sudden deaths was similar for CHIP+ vs. CHIP- cases (36 of 70 [52%] vs. 171 of 329 [51%]). Sequencing of available LV tissue from 61 CHIP+ blood cases revealed 67% (n=41) harbored the same CHIP mutation identified in blood at &gt;0.2% VAF (range 0.2%-4.3%). Proportion of arrhythmic causes among sudden deaths was significantly higher in cases where both blood and LV were CHIP+ (24 of 41 [58.5%] vs. 5 of 19 [26.3%] CHIP+ blood/CHIP- LV, p=0.02). Conclusions: Prevalence of CHIP positivity at sudden death is similar to published studies and correlated with age. CHIP+ status in myocardial tissue but not peripheral blood was associated with arrhythmic causes of sudden death, suggesting a direct tissue effect of CHIP-mutant macrophages.

Clonal Hematopoiesis Is Associated with Non-Myeloid Subsequent Malignant Neoplasms after Autologous Hematopoietic Cell Transplantation

The CD33 SNP rs3865444 modulates the association of clonal hematopoiesis with Alzheimer's disease