Identification and prioritization of myeloid malignancy germline variants in a large cohort of adult patients with AML.

Inherited predisposition to myeloid malignancies is more common than previously appreciated. We analyzed the whole-exome sequencing data of paired leukemia and skin biopsy samples from 391 adult patients from the Beat AML 1.0 consortium. Using the 2015 American College of Medical Genetics and Genomics (ACMG) guidelines for variant interpretation, we curated 1547 unique variants from 228 genes. The pathogenic/likely pathogenic (P/LP) germline variants were identified in 53 acute myeloid leukemia (AML) patients (13.6%) in 34 genes, including 6.39% (25/391) of patients harboring P/LP variants in genes considered clinically actionable (tier 1). 41.5% of the 53 patients with P/LP variants were in genes associated with the DNA damage response. The most frequently mutated genes were CHEK2 (8 patients) and DDX41 (7 patients). Pathogenic germline variants were also found in new candidate genes (DNAH5, DNAH9, DNMT3A, and SUZ12). No strong correlation was found between the germline mutational rate and age of AML onset. Among 49 patients who have a reported history of at least one family member affected with hematological malignancies, 6 patients harbored known P/LP germline variants and the remaining patients had at least one variant of uncertain significance, suggesting a need for further functional validation studies. Using CHEK2 as an example, we show that three-dimensional protein modeling can be one of the effective methodologies to prioritize variants of unknown significance for functional studies. Further, we evaluated an in silico approach that applies ACMG curation in an automated manner using the tool for assessment and (TAPES) prioritization in exome studies, which can minimize manual curation time for variants. Overall, our findings suggest a need to comprehensively understand the predisposition potential of many germline variants in order to enable closer monitoring for disease management and treatment interventions for affected patients and families.

Chronic Myeloid Leukemia, Version 2.2024, NCCN Clinical Practice Guidelines in Oncology.

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome resulting from a reciprocal translocation between chromosomes 9 and 22 [t9;22] that gives rise to a BCR::ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase in developed countries. Tyrosine kinase inhibitor (TKI) therapy is a highly effective treatment option for patients with chronic phase-CML. The primary goal of TKI therapy in patients with chronic phase-CML is to prevent disease progression to accelerated phase-CML or blast phase-CML. Discontinuation of TKI therapy with careful monitoring is feasible in selected patients. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase-CML.

Entospletinib with decitabine in acute myeloid leukemia with mutant TP53 or complex karyotype: A phase 2 substudy of the Beat AML Master Trial.

BACKGROUND: Patients with acute myeloid leukemia (AML) who have tumor protein p53 (TP53) mutations or a complex karyotype have a poor prognosis, and hypomethylating agents are often used. The authors evaluated the efficacy of entospletinib, an oral inhibitor of spleen tyrosine kinase, combined with decitabine in this patient population. METHODS: This was a multicenter, open-label, phase 2 substudy of the Beat AML Master Trial (ClinicalTrials.gov identifier NCT03013998) using a Simon two-stage design. Eligible patients aged 60 years or older who had newly diagnosed AML with mutations in TP53 with or without a complex karyotype (cohort A; n = 45) or had a complex karyotype without TP53 mutation (cohort B; n = 13) received entospletinib 400 mg twice daily with decitabine 20 mg/m2 on days 1-10 every 28 days for up to three induction cycles, followed by up to 11 consolidation cycles, in which decitabine was reduced to days 1-5. Entospletinib maintenance was given for up to 2 years. The primary end point was complete remission (CR) and CR with hematologic improvement by up to six cycles of therapy. RESULTS: The composite CR rates for cohorts A and B were 13.3% (95% confidence interval, 5.1%-26.8%) and 30.8% (95% confidence interval, 9.1%-61.4%), respectively. The median duration of response was 7.6 and 8.2 months, respectively, and the median overall survival was 6.5 and 11.5 months, respectively. The study was stopped because the futility boundary was crossed in both cohorts. CONCLUSIONS: The combination of entospletinib and decitabine demonstrated activity and was acceptably tolerated in this patient population; however, the CR rates were low, and overall survival was short. Novel treatment strategies for older patients with TP53 mutations and complex karyotype remain an urgent need.

Identifying patients at risk for hereditary myeloid malignancy syndromes incorporating a novel, self-administered questionnaire to an initial screening platform.

INTRODUCTION: Four to 10% of cases of myeloid malignancies are inherited. We report our experience on hereditary myeloid malignancy syndromes (HMMS) incorporating a novel questionnaire in the screening platform for patients with myeloid malignancies and aplastic anemia. METHODS: The questionnaire was sent via electronic patient portal prior to clinic visits. Patients screened positive based on responses to questionnaire items, presence of suspicion disease characteristics (young age, family history, monosomy 7 etc.) and/or presence of signs of HMMS. Those deemed at-risk based on questionnaire responses, clinical features and/or somatic mutation profile were offered germline testing. RESULTS: A total of 408 patients were screened, 141 (35%) were deemed at-risk. Fifty-four (38%) of at-risk patients were seen in the genetics clinic. Forty-one (76%) of the patients seen agreed to germline testing and 13 declined due to cost or personal decision. Twenty pathogenic (P)/likely-pathogenic (LP) germline mutations were identified in 16 (39%) of the tested patients. Five patients also had a variant of uncertain significance (VUS) and an additional 13 had at least 1 VUS without P/LP mutations (total 29 VUS's were found in 18 (44%) of tested patients). The median age of diagnosis for patients with P/LP mutations was 56 years versus 66 years in the entire cohort. CONCLUSION: Incorporating an electronic questionnaire is an effective screening method for HMMS. Many patients declined testing due to cost. These results highlight the importance of germline testing in patients with myeloid malignancies, further research in HMMS, and coverage by healthcare plans.

Durable Remissions with Ivosidenib in IDH1-Mutated Relapsed or Refractory AML.

BACKGROUND: Mutations in the gene encoding isocitrate dehydrogenase 1 ( IDH1) occur in 6 to 10% of patients with acute myeloid leukemia (AML). Ivosidenib (AG-120) is an oral, targeted, small-molecule inhibitor of mutant IDH1. METHODS: We conducted a phase 1 dose-escalation and dose-expansion study of ivosidenib monotherapy in IDH1-mutated AML. Safety and efficacy were assessed in all treated patients. The primary efficacy population included patients with relapsed or refractory AML receiving 500 mg of ivosidenib daily with at least 6 months of follow-up. RESULTS: Overall, 258 patients received ivosidenib and had safety outcomes assessed. Among patients with relapsed or refractory AML (179 patients), treatment-related adverse events of grade 3 or higher that occurred in at least 3 patients were prolongation of the QT interval (in 7.8% of the patients), the IDH differentiation syndrome (in 3.9%), anemia (in 2.2%), thrombocytopenia or a decrease in the platelet count (in 3.4%), and leukocytosis (in 1.7%). In the primary efficacy population (125 patients), the rate of complete remission or complete remission with partial hematologic recovery was 30.4% (95% confidence interval [CI], 22.5 to 39.3), the rate of complete remission was 21.6% (95% CI, 14.7 to 29.8), and the overall response rate was 41.6% (95% CI, 32.9 to 50.8). The median durations of these responses were 8.2 months (95% CI, 5.5 to 12.0), 9.3 months (95% CI, 5.6 to 18.3), and 6.5 months (95% CI, 4.6 to 9.3), respectively. Transfusion independence was attained in 29 of 84 patients (35%), and patients who had a response had fewer infections and febrile neutropenia episodes than those who did not have a response. Among 34 patients who had a complete remission or complete remission with partial hematologic recovery, 7 (21%) had no residual detectable IDH1 mutations on digital polymerase-chain-reaction assay. No preexisting co-occurring single gene mutation predicted clinical response or resistance to treatment. CONCLUSIONS: In patients with advanced IDH1-mutated relapsed or refractory AML, ivosidenib at a dose of 500 mg daily was associated with a low frequency of grade 3 or higher treatment-related adverse events and with transfusion independence, durable remissions, and molecular remissions in some patients with complete remission. (Funded by Agios Pharmaceuticals; ClinicalTrials.gov number, NCT02074839 .).

Genomic landscape of neutrophilic leukemias of ambiguous diagnosis.

Chronic neutrophilic leukemia (CNL), atypical chronic myeloid leukemia (aCML), and myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN-U) are a group of rare and heterogeneous myeloid disorders. There is strong morphologic resemblance among these distinct diagnostic entities as well as a lack of specific molecular markers and limited understanding of disease pathogenesis, which has made diagnosis challenging in certain cases. The treatment has remained empirical, resulting in dismal outcomes. We, therefore, performed whole-exome and RNA sequencing of these rare hematologic malignancies and present the most complete survey of the genomic landscape of these diseases to date. We observed a diversity of combinatorial mutational patterns that generally do not cluster within any one diagnosis. Gene expression analysis reveals enrichment, but not cosegregation, of clinical and genetic disease features with transcriptional clusters. In conclusion, these groups of diseases represent a continuum of related diseases rather than discrete diagnostic entities.

Ex vivo drug response profiling detects recurrent sensitivity patterns in drug-resistant acute lymphoblastic leukemia.

Drug sensitivity and resistance testing on diagnostic leukemia samples should provide important functional information to guide actionable target and biomarker discovery. We provide proof of concept data by profiling 60 drugs on 68 acute lymphoblastic leukemia (ALL) samples mostly from resistant disease in cocultures of bone marrow stromal cells. Patient-derived xenografts retained the original pattern of mutations found in the matched patient material. Stromal coculture did not prevent leukemia cell cycle activity, but a specific sensitivity profile to cell cycle-related drugs identified samples with higher cell proliferation both in vitro and in vivo as leukemia xenografts. In patients with refractory relapses, individual patterns of marked drug resistance and exceptional responses to new agents of immediate clinical relevance were detected. The BCL2-inhibitor venetoclax was highly active below 10 nM in B-cell precursor ALL (BCP-ALL) subsets, including MLL-AF4 and TCF3-HLF ALL, and in some T-cell ALLs (T-ALLs), predicting in vivo activity as a single agent and in combination with dexamethasone and vincristine. Unexpected sensitivity to dasatinib with half maximal inhibitory concentration values below 20 nM was detected in 2 independent T-ALL cohorts, which correlated with similar cytotoxic activity of the SRC inhibitor KX2-391 and inhibition of SRC phosphorylation. A patient with refractory T-ALL was treated with dasatinib on the basis of drug profiling information and achieved a 5-month remission. Thus, drug profiling captures disease-relevant features and unexpected sensitivity to relevant drugs, which warrants further exploration of this functional assay in the context of clinical trials to develop drug repurposing strategies for patients with urgent medical needs.

Immune responses and long-term disease recurrence status after telomerase-based dendritic cell immunotherapy in patients with acute myeloid leukemia.

BACKGROUND: Telomerase activity in leukemic blasts frequently is increased among patients with high-risk acute myeloid leukemia (AML). In the current study, the authors evaluated the feasibility, safety, immunogenicity, and therapeutic potential of human telomerase reverse transcriptase (hTERT)-expressing autologous dendritic cells (hTERT-DCs) in adult patients with AML. METHODS: hTERT-DCs were produced from patient-specific leukapheresis, electroporated with an mRNA-encoding hTERT and a lysosomal-targeting sequence, and cryopreserved. A total of 22 patients with a median age of 58 years (range, 30-75 years) with intermediate-risk or high-risk AML in first or second complete remission (CR) were enrolled. hTERT-DCs were generated for 24 patients (73%). A median of 17 intradermal vaccinations (range, 6-32 intradermal vaccinations) containing 1×107 cells were administered as 6 weekly injections followed by 6 biweekly injections. A total of 21 patients (16 in first CR, 3 in second CR, and 2 with early disease recurrence) received hTERT-DCs. RESULTS: hTERT-DCs were well tolerated with no severe toxicities reported, with the exception of 1 patient who developed idiopathic thrombocytopenic purpura. Of the 19 patients receiving hTERT-DCs in CR, 11 patients (58%) developed hTERT-specific T-cell responses that primarily were targeted toward hTERT peptides with predicted low human leukocyte antigen (HLA)-binding affinities. With a median follow-up of 52 months, 58% of patients in CR (11 of 19 patients) were free of disease recurrence at the time of their last follow-up visit; 57% of the patients who were aged ≥60 years (4 of 7 patients) also were found to be free of disease recurrence at a median follow-up of 54 months. CONCLUSIONS: The generation of hTERT-DCs is feasible and vaccination with hTERT-DCs appears to be safe and may be associated with favorable recurrence-free survival. Cancer 2017;123:3061-72. © 2017 American Cancer Society.

Oncogenic CSF3R mutations in chronic neutrophilic leukemia and atypical CML.

BACKGROUND: The molecular causes of many hematologic cancers remain unclear. Among these cancers are chronic neutrophilic leukemia (CNL) and atypical (BCR-ABL1-negative) chronic myeloid leukemia (CML), both of which are diagnosed on the basis of neoplastic expansion of granulocytic cells and exclusion of genetic drivers that are known to occur in other myeloproliferative neoplasms and myeloproliferative-myelodysplastic overlap neoplasms. METHODS: To identify potential genetic drivers in these disorders, we used an integrated approach of deep sequencing coupled with the screening of primary leukemia cells obtained from patients with CNL or atypical CML against panels of tyrosine kinase-specific small interfering RNAs or small-molecule kinase inhibitors. We validated candidate oncogenes using in vitro transformation assays, and drug sensitivities were validated with the use of assays of primary-cell colonies. RESULTS: We identified activating mutations in the gene encoding the receptor for colony-stimulating factor 3 (CSF3R) in 16 of 27 patients (59%) with CNL or atypical CML. These mutations segregate within two distinct regions of CSF3R and lead to preferential downstream kinase signaling through SRC family-TNK2 or JAK kinases and differential sensitivity to kinase inhibitors. A patient with CNL carrying a JAK-activating CSF3R mutation had marked clinical improvement after the administration of the JAK1/2 inhibitor ruxolitinib. CONCLUSIONS: Mutations in CSF3R are common in patients with CNL or atypical CML and represent a potentially useful criterion for diagnosing these neoplasms. (Funded by the Leukemia and Lymphoma Society and others.).

Everolimus for patients with mantle cell lymphoma refractory to or intolerant of bortezomib: multicentre, single-arm, phase 2 study.

The multicentre, open-label, two-stage, single-arm, phase 2, PILLAR (PIvotaL Lymphoma triAls of RAD001)-1 study (NCT00702052) assessed the efficacy and safety of everolimus 10 mg/d in adults with confirmed mantle cell lymphoma (MCL) refractory to or intolerant of bortezomib who received ≥1 other antineoplastic agent, either separately or in combination with bortezomib. Primary endpoint was overall response rate (ORR) per investigator review according to the response criteria for malignant lymphoma. Secondary endpoints included progression-free survival (PFS), overall survival (OS) and safety. Fifty-eight patients were enrolled from August 2008-January 2011. Five partial responses were observed (ORR 8·6%; 90% confidence interval [CI] 3·5-17·3%); the study did not meet the prespecified objective of ≥8 objective responses among 57 patients. Median PFS and OS were 4·4 months (95% CI 3·5-6·1) and 16·9 months (95% CI 14·4-29·9), respectively. Grade 3/4 non-haematological toxicities occurred in 70·7% of patients. Based on laboratory values, grade 3/4 thrombocytopenia, neutropenia and anaemia occurred in 13·8%, 13·8% and 8·6% of patients, respectively. Everolimus demonstrated modest activity and acceptable tolerability in heavily pretreated patients with MCL refractory to or intolerant of bortezomib. Future studies evaluating everolimus in a less refractory population or in combination with other targeted therapies in refractory MCL are warranted.

Racial and ethnic disparities in Acute Myeloid Leukemia: 15-year experience at a safety net hospital system.

Despite recent therapeutic advances, ethnic minorities in the U.S. continue to have disproportionately poor outcomes in many hematologic malignancies including AML. We identified 162 adult AML patients treated at a non-transplant safety net hospital from 2007 to 2022 and evaluated differences in disease characteristics, treatment and clinical outcomes based on race and ethnicity. Our cohort consisted of 82 (50.6%) Hispanic, 36 (22.2%) non-Hispanic black and 44 (27.2%) non-Hispanic white and Asian patients. Median age at diagnosis was 42.5, 49.0 and 52.5 years respectively (p=0.025). Hispanics had higher rates of intermediate and high-risk disease (p=0.699) and received high intensity induction and consolidation chemotherapy at lower rates (p=0.962), although differences did not reach statistical significance. Despite this, similar remission rates were achieved. Hispanics with high-risk disease had longer overall survival (OS) than the combined non-Hispanic cohort (mOS 14 m vs 7 m, p=0.030). Multivariate regression analysis showed that OS was negatively associated with age (HR 1.023, p=0.006), intermediate (HR 3.431, p=0.0003) and high-risk disease (HR 4.689, p<0.0001) and positively associated with Hispanic ethnicity (HR 0.614, p=0.026). This report suggests that contrary to other studies, Hispanics, particularly those with high-risk AML, may have improved OS compared to other ethnic groups. These results are unique to our safety net hospital setting where common barriers to medical care and healthcare disparities are largely mitigated.

A study to assess the efficacy of enasidenib and risk-adapted addition of azacitidine in newly diagnosed IDH2-mutant AML.

ABSTRACT: Enasidenib (ENA) is an inhibitor of isocitrate dehydrogenase 2 (IDH2) approved for the treatment of patients with IDH2-mutant relapsed/refractory acute myeloid leukemia (AML). In this phase 2/1b Beat AML substudy, we applied a risk-adapted approach to assess the efficacy of ENA monotherapy for patients aged ≥60 years with newly diagnosed IDH2-mutant AML in whom genomic profiling demonstrated that mutant IDH2 was in the dominant leukemic clone. Patients for whom ENA monotherapy did not induce a complete remission (CR) or CR with incomplete blood count recovery (CRi) enrolled in a phase 1b cohort with the addition of azacitidine. The phase 2 portion assessing the overall response to ENA alone demonstrated efficacy, with a composite complete response (cCR) rate (CR/CRi) of 46% in 60 evaluable patients. Seventeen patients subsequently transitioned to phase 1b combination therapy, with a cCR rate of 41% and 1 dose-limiting toxicity. Correlative studies highlight mechanisms of clonal elimination with differentiation therapy as well as therapeutic resistance. This study demonstrates both efficacy of ENA monotherapy in the upfront setting and feasibility and applicability of a risk-adapted approach to the upfront treatment of IDH2-mutant AML. This trial is registered at www.clinicaltrials.gov as #NCT03013998.

Beat-AML 2024 ELN-refined risk stratification for older adults with newly diagnosed AML given lower-intensity therapy.

ABSTRACT: Although the 2022 European LeukemiaNet (ELN) acute myeloid leukemia (AML) risk classification reliably predicts outcomes in younger patients treated with intensive chemotherapy, it is unclear whether it applies to adults ≥60 years treated with lower-intensity treatment (LIT). We aimed to test the prognostic impact of ELN risk in patients with newly diagnosed (ND) AML aged ≥60 years given LIT and to further refine risk stratification for these patients. A total of 595 patients were included: 11% had favorable-, 11% intermediate-, and 78% had adverse-risk AML. ELN risk was prognostic for overall survival (OS) (P < .001) but did not stratify favorable- from intermediate-risk (P = .71). Within adverse-risk AML, the impact of additional molecular abnormalities was further evaluated. Multivariable analysis was performed on a training set (n = 316) and identified IDH2 mutation as an independent favorable prognostic factor, and KRAS, MLL2, and TP53 mutations as unfavorable (P < .05). A "mutation score" was calculated for each combination of these mutations, assigning adverse-risk patients to 2 risk groups: -1 to 0 points ("Beat-AML intermediate") vs 1+ points ("Beat-AML adverse"). In the final refined risk classification, ELN favorable- and intermediate-risk were combined into a newly defined "Beat-AML favorable-risk" group, in addition to mutation scoring within the ELN adverse-risk group. This approach redefines risk for older patients with ND AML and proposes refined Beat-AML risk groups with improved discrimination for OS (2-year OS, 48% vs 33% vs 11%, respectively; P < .001), providing patients and providers additional information for treatment decision-making.

Anti-Spike Antibody Responses in Allogeneic Stem Cell Transplant Recipients to Two Doses of COVID-19 mRNA Vaccination: A Retrospective, Single-Center Analysis.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients were excluded from the initial SARS-CoV-2 mRNA vaccination efficacy trials. Suboptimal vaccine responses have been reported in immunocompromised cohorts such as patients with solid tumors or hematologic malignancies, suggesting the need for additional research. Widespread data on the antibody responses and vaccine efficacy in allo-HSCT recipients is limited. In our single-center, retrospective study, we analyzed the anti-spike IgG antibody responses in 75 allo-HSCT recipients who received a series of two doses of mRNA vaccination. We collected data on previous COVID-19 infection, B and T lymphocyte recovery, donor types, graft-vs.-host disease (GVHD), and immunosuppressive medications at the time of vaccination. With the original variant, a cutoff of 4,160 arbitrary units (AU)/mL has been correlated with a 0.95 probability of a viral neutralization. We also examined the number of allo-HSCT recipients who achieved this conservative threshold. To our knowledge, no correlate exists for the currently prevalent Omicron variant and viral neutralization. Despite 29.3% (22/75) of patients being on systemic immunosuppressive medications due to chronic GVHD, positive antibody responses > 50 AU/mL were seen in 96% of patients. However, only 48% (36/75) of patients were above the neutralizing antibody threshold. Those with previous COVID-19 infection had significantly higher antibody responses. Although encouraging, the variability of the responses underscores the concept of ongoing antibody monitoring as well as consideration of additional doses of the COVID-19 vaccine in this cohort.

Long-term outcome of progressive multifocal leukoencephalopathy with recombinant interleukin-2 treatment and an associated increase in the number of HPyV-2-specific T-cells: a case report.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by reactivation of the human polyomavirus 2 (HPyV-2). PML is associated with a high morbidity and mortality rate and there is currently no standard curative therapy. We report short-term immunologic response and long-term clinical outcomes in a patient diagnosed with follicular lymphoma (FL) who developed PML. Diagnosis of PML was established conclusively based on findings from a brain biopsy. The patient was treated with recombinant interleukin 2 (IL-2) and showed rapid clinical improvement. HPyV-2-specific T-cells were tracked longitudinally and correlation with clinical status, viral load, and radiographic imaging was documented. After the progression of the patient's FL, which required an allogeneic bone marrow transplant, the patient prophylactically received human leukocyte antigen-matched donor-derived HPyV-2 T-cells to prevent the recurrence of the PML as part of a clinical trial. Twelve years after the initial diagnosis of PML, he did not develop a relapse of his PML, supporting data that therapies that increase HPyV-2-specific T-cells, including IL-2, may be effective in the management of PML.

Clinical and molecular characteristics associated with Vitamin C deficiency in myeloid malignancies; real world data from a prospective cohort.

Vitamin C is an essential vitamin that acts as a co-factor for many enzymes involved in epigenetic regulation in humans. Low vitamin C levels in hematopoietic stem cells (HSC) promote self-renewal and vitamin C supplementation retards leukaemogenesis in vitamin C-deficient mouse models. Studies on vitamin C levels in patients with myeloid malignancies are limited. We thus conducted a retrospective analysis on a prospective cohort of patients with myeloid malignancies on whom plasma vitamin C levels were measured serially at diagnosis and during treatment. Baseline characteristics including hematological indices, cytogenetics, and molecular mutations are described in this cohort. Among 64 patients included in our study, 11 patients (17%) had low vitamin C levels. We noted a younger age at diagnosis for patients with myeloid malignancies who had low plasma vitamin C levels. Patients with low plasma vitamin C levels were more likely to have acute myeloid leukemia compared to other myeloid malignancies. Low vitamin C levels were associated with ASXL1 mutations. Our study calls for further multi-institutional studies to understand the relevance of low plasma vitamin C level in myeloid neoplasms, the role of vitamin C deficiency in leukemogenesis, and the potential benefit of vitamin C supplementation.

Post-transplant cyclophosphamide and early mixed donor Chimerism in myeloid malignancies; a single-center experience.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative option for high-risk myeloid malignancies. Post-transplant cyclophosphamide (PT-Cy) has proven to be effective for graft versus host disease (GVHD) prophylaxis. Given that graft-versus-tumor (GVT) effect plays a major role in reducing the risk of disease relapse, the application of PT-Cy must balance the risk of relapse. Mixed chimerism (MC) refers to a state of concurrent presence of recipient and donor cells post allo-HSCT which may precede relapse disease. OBJECTIVE: We investigated the impact of PT-Cy on early MC (EMC) and disease relapse in patients with a myeloid malignancy post allo-HSCT. STUDY DESIGN: This retrospective single-center study included patients that underwent allo-HSCT between 2015 and 2021. Patient and disease characteristics were collected from the electronic health records. EMC was defined as <95% donor cells at day 90-120 post allo-HSCT. RESULTS: A total of 144 patient that received an allo-HSCT were included in the study. One hundred and eight (75%) patients received PT-Cy as part of the GVHD prophylaxis regimen. The majority underwent allo-HSCT for acute myeloid leukemia (62%) or myelodysplastic syndrome (31%). Sixty-five percent received allo-HSCT from a matched unrelated donor transplant and 65% received a myeloablative conditioning regimen. A lower rate of chronic GVHD (p = 0.03) and a higher rate of EMC (p = 0.04) were observed in patients that received PT-Cy. PT-Cy was not associated with overall survival (OS) and relapse-free survival (RFS). Multivariable analysis identified measurable residual disease status (p = 0.003), hematopoietic cell transplantation-specific comorbidity index (p = 0.012) and chronic GVHD (p = 0.006) as independent prognostic variables for OS. AML-adverse risk (p = 0.004) and EMC (p = 0.018) were independently prognostic for RFS. While EMC overall was not significantly associated with higher risk of relapse, EMC was associated with shorter RFS within adverse-risk AML patients. CONCLUSION: Our study shows that PT-Cy was associated with an increased risk of EMC. The predictive value of EMC for relapse remains unclear and may depend on the underlying disease, which should be validated in a larger cohort.

SARS-CoV-2 Vaccination IgG Antibody Responses in Patients with Hematologic Malignancies in a Myeloid Enriched Cohort: A Single Center Observation.

OBJECTIVE: Patients diagnosed with hematologic malignancies are at increased risk for severe SARS-CoV-2 infection. We evaluated the serological IgG response following two doses of the SARS-CoV-2 vaccine in patients with hematologic malignancies. METHODS: Patients treated at UT Southwestern Medical Center with a diagnosis of a myeloid or lymphoid neoplasm were included. SARS-CoV-2 vaccination response was defined as a positive quantifiable spike IgG antibody titer. RESULTS: Sixty patients were included in the study and 60% were diagnosed with a myeloid neoplasm. The majority (85%) of the patients with a myeloid malignancy and 50% of the patients with a lymphoid malignancy mounted a serological response after receiving two doses of the vaccine. CONCLUSION: Vaccination should be offered irrespective of ongoing treatment or active disease. Findings require validation in a larger cohort of patients.

Disabling Uncompetitive Inhibition of Oncogenic IDH Mutations Drives Acquired Resistance.

Mutations in IDH genes occur frequently in acute myeloid leukemia (AML) and other human cancers to generate the oncometabolite R-2HG. Allosteric inhibition of mutant IDH suppresses R-2HG production in a subset of patients with AML; however, acquired resistance emerges as a new challenge, and the underlying mechanisms remain incompletely understood. Here we establish isogenic leukemia cells containing common IDH oncogenic mutations by CRISPR base editing. By mutational scanning of IDH single amino acid variants in base-edited cells, we describe a repertoire of IDH second-site mutations responsible for therapy resistance through disabling uncompetitive enzyme inhibition. Recurrent mutations at NADPH binding sites within IDH heterodimers act in cis or trans to prevent the formation of stable enzyme-inhibitor complexes, restore R-2HG production in the presence of inhibitors, and drive therapy resistance in IDH-mutant AML cells and patients. We therefore uncover a new class of pathogenic mutations and mechanisms for acquired resistance to targeted cancer therapies. SIGNIFICANCE: Comprehensive scanning of IDH single amino acid variants in base-edited leukemia cells uncovers recurrent mutations conferring resistance to IDH inhibition through disabling NADPH-dependent uncompetitive inhibition. Together with targeted sequencing, structural, and functional studies, we identify a new class of pathogenic mutations and mechanisms for acquired resistance to IDH-targeting cancer therapies. This article is highlighted in the In This Issue feature, p. 1.

The impact of race and ethnicity on outcomes of patients with myelodysplastic syndromes: a population-based analysis.

Race and ethnic backgrounds affect the disease characteristics and clinical outcomes in many cancers, including acute myeloid leukemia; however, the association of race/ethnicity on myelodysplastic syndrome (MDS) is still controversial. Therefore, we aimed to study the impact of race/ethnicity on the disease characteristics and survival outcomes in patients with MDS. Adult patients with MDS diagnosed in 2004-2016 were selected using the SEER database. Race/ethnicity was categorized as non-Hispanic White (NHW), non-Hispanic Black (NHB), and Hispanic. Hispanic and NHB patients had significantly lower incidence rate ratio (IRR) in age group ≥01 years (p < .001) compared to NHW; however, in the age group <50 years, NHB patients had significantly higher IRR with an increased incidence rate of 49%. NHB patients had better overall survival than Hispanic and NHW patients (p < .001), even after adjusting for confounding variables. MDS have significant differences in age at diagnosis, disease risk, and survival outcomes based on racial/ethnic backgrounds.