MS4A3 promotes differentiation in chronic myeloid leukemia by enhancing common ß-chain cytokine receptor endocytosis.

The chronic phase of chronic myeloid leukemia (CP-CML) is characterized by the excessive production of maturating myeloid cells. As CML stem/progenitor cells (LSPCs) are poised to cycle and differentiate, LSPCs must balance conservation and differentiation to avoid exhaustion, similar to normal hematopoiesis under stress. Since BCR-ABL1 tyrosine kinase inhibitors (TKIs) eliminate differentiating cells but spare BCR-ABL1-independent LSPCs, understanding the mechanisms that regulate LSPC differentiation may inform strategies to eliminate LSPCs. Upon performing a meta-analysis of published CML transcriptomes, we discovered that low expression of the MS4A3 transmembrane protein is a universal characteristic of LSPC quiescence, BCR-ABL1 independence, and transformation to blast phase (BP). Several mechanisms are involved in suppressing MS4A3, including aberrant methylation and a MECOM-C/EBPε axis. Contrary to previous reports, we find that MS4A3 does not function as a G1/S phase inhibitor but promotes endocytosis of common ß-chain (ßc) cytokine receptors upon GM-CSF/IL-3 stimulation, enhancing downstream signaling and cellular differentiation. This suggests that LSPCs downregulate MS4A3 to evade ßc cytokine-induced differentiation and maintain a more primitive, TKI-insensitive state. Accordingly, knockdown (KD) or deletion of MS4A3/Ms4a3 promotes TKI resistance and survival of CML cells ex vivo and enhances leukemogenesis in vivo, while targeted delivery of exogenous MS4A3 protein promotes differentiation. These data support a model in which MS4A3 governs response to differentiating myeloid cytokines, providing a unifying mechanism for the differentiation block characteristic of CML quiescence and BP-CML. Promoting MS4A3 reexpression or delivery of ectopic MS4A3 may help eliminate LSPCs in vivo.

International Consensus Classification of Myeloid Neoplasms and Acute Leukemias: integrating morphologic, clinical, and genomic data.

The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

Quantification of measurable residual disease using duplex sequencing in adults with acute myeloid leukemia.

The presence of measurable residual disease (MRD) is strongly associated with treatment outcomes in acute myeloid leukemia (AML). Despite the correlation with clinical outcomes, MRD assessment has yet to be standardized or routinely incorporated into clinical trials and discrepancies have been observed between different techniques for MRD assessment. In 62 patients with AML, aged 18-60 years, in first complete remission after intensive induction therapy on the randomized phase III SWOG-S0106 clinical trial (clinicaltrials gov. Identifier: NCT00085709), MRD detection by centralized, high-quality multiparametric flow cytometry was compared with a 29-gene panel utilizing duplex sequencing (DS), an ultrasensitive next-generation sequencing method that generates double-stranded consensus sequences to reduce false positive errors. MRD as defined by DS was observed in 22 (35%) patients and was strongly associated with higher rates of relapse (68% vs. 13%; hazard ratio [HR] =8.8; 95% confidence interval [CI]: 3.2-24.5; P<0.001) and decreased survival (32% vs. 82%; HR=5.6; 95% CI: 2.3-13.8; P<0.001) at 5 years. DS MRD strongly outperformed multiparametric flow cytometry MRD, which was observed in ten (16%) patients and marginally associated with higher rates of relapse (50% vs. 30%; HR=2.4; 95% CI: 0.9-6.7; P=0.087) and decreased survival (40% vs. 68%; HR=2.5; 95% CI: 1.0-6.3; P=0.059) at 5 years. Furthermore, the prognostic significance of DS MRD status at the time of remission for subsequent relapse was similar on both randomized arms of the trial. These findings suggest that next-generation sequencing-based AML MRD testing is a powerful tool that could be developed for use in patient management and for early anti-leukemic treatment assessment in clinical trials.

Treatment of chronic-phase chronic myeloid leukemia in patients randomized to dasatinib or imatinib after suboptimal responses to three months of imatinib therapy: final 5-year results from DASCERN.

Early molecular response (EMR) at 3 months is predictive of improved overall survival (OS) and progression-free survival (PFS) in patients with chronic myeloid leukemia in the chronic phase (CML-CP). Although about one-third of patients treated with first-line imatinib do not achieve EMR, long-term OS and PFS are still observed in most patients. DASCERN (NCT01593254) is a prospective, phase IIb, randomized trial evaluating a switch to dasatinib in patients who have not achieved EMR after 3 months of treatment with first-line imatinib. Early analysis demonstrated an improved major molecular response (MMR) rate at 12 months with dasatinib versus imatinib (29% vs. 13%, P=0.005). Here, we report results from the final 5-year follow-up. In total, 174 patients were randomized to dasatinib and 86 to remain on imatinib. Forty-six (53%) patients who remained on imatinib but subsequently experienced failure were allowed to cross over to dasatinib per protocol. At a minimum follow-up of 60 months, the cumulative MMR rate was significantly higher in patients randomized to dasatinib versus imatinib (77% vs. 44%, P.

Ultra-deep mutational landscape in chronic lymphocytic leukemia uncovers dynamics of resistance to targeted therapies.

BTK inhibitors, Bcl-2 inhibitors, and other targeted therapies have significantly improved the outcomes of patients with chronic lymphocytic leukemia (CLL). With increased survivorship, monitoring disease and deciphering potential mechanisms of resistance to these agents are critical for devising effective treatment strategies. We used duplex sequencing, a technology that enables detection of mutations at ultra-low allelic frequencies, to identify mutations in five genes associated with drug resistance in CLL and followed their evolution in two patients who received multiple targeted therapies and ultimately developed disease progression on pirtobrutinib. In both patients we detected variants that expanded and reached significant cancer cell fractions (CCF). In patient R001, multiple known resistance mutations in both BTK and PLCG2 appeared following progression on zanubrutinib (BTK p.L528W, p.C481S; PLCG2 S707F, L845F, R665W, and D993H). In contrast, patient R002 developed multiple BTK mutations following acalabrutinib treatment, including known resistance mutations p.C481R, p.T474I and p.C481S. We found that pirtobrutinib was able to suppress, but not completely eradicate, BTK p.C481S mutations in both patients, but other resistance mutations such as mutations in PLCG2 and new BTK mutations increased while the patients were receiving pirtobrutinib. For example, BTK p.L528W in patient R001 increased in frequency more than 1,000-fold (from a CCF of 0.02% to 35%), and the CCF in p.T474I in patient R002 increased from 0.03% to 4.2% (more than 100-fold). Our data illuminate the evolutionary dynamics of resistant clones over the patients' disease course and under selective pressure from different targeted treatments.

Hematological, clinical, cytogenetic and molecular profiles of confirmed chronic myeloid leukemia patients at presentation at a tertiary care teaching hospital in Addis Ababa, Ethiopia: a cross-sectional study.

BACKGROUND: In low-income countries there is insufficient evidence on hematological, clinical, cytogenetic and molecular profiles among new CML patients. Therefore, we performed this study among newly confirmed CML patients at Tikur Anbesa Specialized Hospital (TASH), Ethiopia. OBJECTIVE: To determine the hematological, clinical, cytogenetic and molecular profiles of confirmed CML patients at tertiary care teaching hospital in Addis Ababa, Ethiopia. METHODS: A facility-based cross-sectional study was conducted to evaluate hematological, clinical, cytogenetic and molecular profiles of confirmed CML patients at TASH from August 2021 to December 2022. A structured questionnaire was used to collect the patients' sociodemographic information, medical history and physical examination, and blood samples were also collected for hematological, cytogenetic and molecular tests. Descriptive statistics were used to analyze the sociodemographic, hematological, clinical, cytogenetic and molecular profiles of the study participants. RESULTS: A total of 251 confirmed new CML patients were recruited for the study. The majority of patients were male (151 [60.2%]; chronic (CP) CML, 213 [84.7%]; and had a median age of 36 years. The median (IQR) WBC, RBC, HGB and PLT counts were 217.7 (155.62-307.4) x103/µL, 3.2 (2.72-3.6) x106/µL, 9.3 (8.2-11) g/dl and 324 (211-499) x 103/µL, respectively. All patients had leukocytosis, and 92.8%, 95.6% and 99.2% of the patients developed anemia, hyperleukocytosis and neutrophilia, respectively. Fatigue, abdominal pain, splenomegaly and weight loss were the common signs and symptoms observed among CML patients. Approximately 86.1% of the study participants were Philadelphia chromosome positive (Ph+) according to fluorescence in situ hybridization (FISH). P210, the major breakpoint protein, transcript was detected by both qualitative polymerase chain reaction (PCR) and quantitative real time polymerase chain reaction (PCR). CONCLUSION: During presentation, most CML patients presented with hyperleukocytosis, neutrophilia and anemia at TASH, Addis Ababa. Fatigue, abdominal pain, splenomegaly and weight loss were the most common signs and symptoms observed in the CML patients. Most CML patients were diagnosed by FISH, and p120 was detected in all CML patients diagnosed by PCR. The majority of CML patients arrive at referral center with advanced signs and symptoms, so better to decentralize the service to peripheral health facilities.

Molecular response in newly diagnosed chronic-phase chronic myeloid leukemia: prediction modeling and pathway analysis.

Tyrosine kinase inhibitor therapy revolutionized chronic myeloid leukemia treatment and showed how targeted therapy and molecular monitoring could be used to substantially improve survival outcomes. We used chronic myeloid leukemia as a model to understand a critical question: why do some patients have an excellent response to therapy, while others have a poor response? We studied gene expression in whole blood samples from 112 patients from a large phase III randomized trial (clinicaltrials gov. Identifier: NCT00471497), dichotomizing cases into good responders (BCR::ABL1 ≤10% on the International Scale by 3 and 6 months and ≤0.1% by 12 months) and poor responders (failure to meet these criteria). Predictive models based on gene expression demonstrated the best performance (area under the curve =0.76, standard deviation =0.07). All of the top 20 pathways overexpressed in good responders involved immune regulation, a finding validated in an independent data set. This study emphasizes the importance of pretreatment adaptive immune response in treatment efficacy and suggests biological pathways that can be targeted to improve response.

Patient- and physician-reported pain after tyrosine kinase inhibitor discontinuation among patients with chronic myeloid leukemia.

For patients with optimally treated chronic myeloid leukemia (CML), discontinuation of tyrosine kinase inhibitor (TKI) therapy can lead to treatment-free remission. In previous trials, TKI discontinuation has been associated with increased musculoskeletal pain in some patients ("withdrawal syndrome"), based on physician-reported adverse events (AE). Patient-reported pain has not been described. The Life After Stopping TKI study was a 14-site prospective, non-randomized clinical trial of TKI discontinuation. We defined increased pain after discontinuation as: (i) a physician-reported pain AE, (ii) a 2-level increase in self-reported musculoskeletal pain (4-level single item), or (iii) initiation of a medication for pain. We plotted the trajectory of patient-reported pain over time using a piecewise mixed-effects ordinal logistic model. Within 3 months of discontinuation, 35 of 172 patients (20.3%) had a physician-reported pain AE, 22 of 172 (12.8%) had an increase in self-reported pain, and 18 of 154 (11.7%) initiated a pain medication. Agreement among these measures was limited; overall, 60 of 172 patients (34.9%) had increased pain. Three patients (1.7%) restarted a TKI because of pain. The modelpredicted trajectory showed an increase in pain in the first 3 months followed by a decrease, returning to baseline levels by 6 months and further decreasing after that. This trajectory was similar among patients who did and did not restart TKI, suggesting that resuming a TKI for withdrawal syndrome may be necessary for some, but other approaches to manage pain should be tried so that patients can remain in treatment-free remission when possible.

A graphical, interactive and GPU-enabled workflow to process long-read sequencing data.

BACKGROUND: Long-read sequencing has great promise in enabling portable, rapid molecular-assisted cancer diagnoses. A key challenge in democratizing long-read sequencing technology in the biomedical and clinical community is the lack of graphical bioinformatics software tools which can efficiently process the raw nanopore reads, support graphical output and interactive visualizations for interpretations of results. Another obstacle is that high performance software tools for long-read sequencing data analyses often leverage graphics processing units (GPU), which is challenging and time-consuming to configure, especially on the cloud. RESULTS: We present a graphical cloud-enabled workflow for fast, interactive analysis of nanopore sequencing data using GPUs. Users customize parameters, monitor execution and visualize results through an accessible graphical interface. The workflow and its components are completely containerized to ensure reproducibility and facilitate installation of the GPU-enabled software. We also provide an Amazon Machine Image (AMI) with all software and drivers pre-installed for GPU computing on the cloud. Most importantly, we demonstrate the potential of applying our software tools to reduce the turnaround time of cancer diagnostics by generating blood cancer (NB4, K562, ME1, 238 MV4;11) cell line Nanopore data using the Flongle adapter. We observe a 29x speedup and a 93x reduction in costs for the rate-limiting basecalling step in the analysis of blood cancer cell line data. CONCLUSIONS: Our interactive and efficient software tools will make analyses of Nanopore data using GPU and cloud computing accessible to biomedical and clinical scientists, thus facilitating the adoption of cost effective, fast, portable and real-time long-read sequencing.

Molecular testing of chronic myeloid leukaemia in low resource areas.

Most cancer cases occur in areas of low resources. The diagnosis, treatment and monitoring of cancers is especially challenging in these locations. Unique partnerships exist between non-profit organisations and pharmaceutical companies to provide free drugs to CML patients throughout the world if the diagnosis can be rigorously and unambiguously established. But there lies the rub: How do you perform molecular diagnostics in areas where even electricity is unreliable? Here we describe the evolution of testing patients from low resource areas, which, when merged with a remarkable effort to bring tyrosine kinase inhibitors to patients across the globe, have led to survival outcomes similar to cases in industrialised countries.

Capillary-Mediated Single-Cell Dispenser.

Single-cell manipulation, sorting, and dispensing into multiwell plates is useful for single-cell multiomics studies. Here, we develop a single-cell dispenser inspired by electrohydrodynamic jet printing that achieves accurate droplet generation and single-cell sorting and dispensing using fused silica capillary tubing as both the optical detection window and nozzle for droplet dispensing. Parameters that affect droplet dispensing performance-capillary inner and outer diameter, flow rate, applied voltage, and solution properties-were optimized systematically with COMSOL simulations and experimentation. Small (5-10 nL) droplets were obtained by using 100-µm inner diameter and 160-µm outer diameter capillary tubing and allowed efficient encapsulation and dispensing of single cells. We demonstrate an application of this easy-to-assemble single-cell dispenser by sorting and dispensing cells into multiwell plates for single-cell PCR analysis.

New approaches to molecular monitoring in CML (and other diseases).

Chronic myeloid leukemia (CML) is the model cancer, demonstrating the clinical benefits of targeted therapy and the power of molecular diagnostics and monitoring. In CML, the BCR-ABL1 fusion gene and its companion messenger RNA offers a unique target differentiating cancer from the normal cell, affording the potential for very sensitive and specific assays. Because CML is such an ideal model, new methods are arising that should make testing in CML faster, more reliable, and reach a greater sensitivity. New ultrasensitive sequencing approaches, coupled with single-cell genomic approaches, further the study of measurable residual disease, clonal heterogeneity, and promise to make clinical trials more innovative and informative. These methods should be able to be transferred to other hematological and solid malignancies.

Analysis of the gap in PCR monitoring availability for patients with chronic myeloid leukemia in 60 low- and middle-income countries.

PURPOSE: To estimate the resource gap in the polymerase chain reaction (PCR) monitoring for patients with chronic myeloid leukemia (CML) in low- and middle-income countries (LMICs). METHODS: We developed a model of demand and supply of PCR monitoring of CML patients in 60 LMICs. PCR testing was assumed to use Cepheid's GeneXpert® IV system. We included costs of GeneXpert® instruments, uninterrupted power supplies, warranties, calibration kits, test cartridges, and shipping. We calculated the country-specific monetary gap in PCR monitoring, stratified by country priority defined as the availability of tyrosine kinase inhibitors (TKIs) through The Max Foundation initiatives. RESULTS: The 5-year gap in PCR monitoring was $29.1 million across all countries, 22% ($6.4 million) in countries with all five TKIs available, 20% ($5.7 million) in countries with four TKIs available, 50% ($14.5 million) in countries with three TKIs available, 8% ($2.2 million) in countries with two TKIs available, and 1% ($0.3 million) in countries with one TKI available. The gap was highest in South Asia (52%; $15.1 million) and lowest in Latin America (6%; $1.9 million). Excluding labor costs, the bulk of the resource needs (86%; $25.2 million) were for procurement of BCR-ABL cartridges. CONCLUSION: Removing the 5-year gap in PCR monitoring capacity for CML in LMICs will require the mobilization of significant resources and will likely lead to better treatment outcomes and reduced treatment costs through optimization of treatment, discontinuation of therapy in appropriate patients, and facilitation of clinical research. Development of streamlined monitoring guidelines for resource-limited countries should be considered.

Predictors of tyrosine kinase inhibitor adherence trajectories in patients with newly diagnosed chronic myeloid leukemia.

INTRODUCTION: Although consistent use of tyrosine kinase inhibitors (TKIs) confers significant improvements in long-term survival for individuals with chronic myeloid leukemia (CML), only 70% of CML patients are adherent to TKIs. Understanding the factors that contribute to non-adherence and establishing dynamic adherence patterns in this population are essential aspects of targeted drug monitoring and intervention strategies. METHODS: Newly diagnosed CML patients were identified in the MarketScan database and relevant covariate values extracted. Proportion of days covered (PDC) per 30-day interval was used to calculate adherence over a 12-month follow-up period. We conducted a latent profile analysis (LPA) on these PDC estimates to identify distinct, dynamic patterns of TKI adherence. Identified trajectories were grouped into four clinically relevant categories and predictors of membership in these categories were determined via multinomial logistic regression. RESULTS: Four broad adherence categories were identified from the LPA: never adherent, initially non-adherent becoming adherent, initially adherent becoming non-adherent, and stable adherent. Results from the subsequent multinomial logistic regression indicated that younger age, female sex, greater monthly financial burden, fewer comorbidities, fewer concomitant medications, year of diagnosis, higher starting dose, TKI type, and a longer duration from diagnosis to treatment were significantly associated with membership in at least one of the three non-stable adherent groups. CONCLUSION: Select sociodemographic and clinical characteristics were found to predict membership in clinically meaningful groups of longitudinal TKI adherence. These findings could have major implications for informing personalized monitoring and intervention strategies for individuals who are likely to be non-adherent.

Targeted Sequencing Improves DIPSS-Plus Prognostic Scoring in Myelofibrosis Patients Undergoing Allogeneic Transplantation.

Primary myelofibrosis (MF) and secondary MF developing after polycythemia vera or essential thrombocythemia are clonal disorders of hematopoiesis. Currently the sole therapy offering the potential of cure is hematopoietic cell transplantation (HCT). Several risk classification systems including clinical, hematologic, and mutational parameters have been proposed. We analyzed the mutational landscape in addition to the Dynamic International Prognostic Scoring System (DIPSS)-plus in 55 patients with MF to determine the combined impact on post-HCT outcome. Mutations, analyzed in 75 genes, were most common in JAK2, CALR, ASXL1, TET2, GATA2, EZH2, U2AF1, and ETV6. Patients with ≥3 mutations in addition to JAK2 or CALR mutations had a higher post-transplantation relapse rate and nonrelapse mortality than patients with fewer mutations, independent of DIPSS-plus risk. The presence of higher numbers of mutations identified patients at the greatest risk of relapse within the highest overall risk group as determined by DIPSS-plus. These findings are consistent with molecular risk classifications for patients who do not undergo HCT and support the proposed transplantation risk classification incorporating mutational information.

Long-Term Outcomes of Imatinib Treatment for Chronic Myeloid Leukemia.

BACKGROUND: Imatinib, a selective BCR-ABL1 kinase inhibitor, improved the prognosis for patients with chronic myeloid leukemia (CML). We conducted efficacy and safety analyses on the basis of more than 10 years of follow-up in patients with CML who were treated with imatinib as initial therapy. METHODS: In this open-label, multicenter trial with crossover design, we randomly assigned patients with newly diagnosed CML in the chronic phase to receive either imatinib or interferon alfa plus cytarabine. Long-term analyses included overall survival, response to treatment, and serious adverse events. RESULTS: The median follow-up was 10.9 years. Given the high rate of crossover among patients who had been randomly assigned to receive interferon alfa plus cytarabine (65.6%) and the short duration of therapy before crossover in these patients (median, 0.8 years), the current analyses focused on patients who had been randomly assigned to receive imatinib. Among the patients in the imatinib group, the estimated overall survival rate at 10 years was 83.3%. Approximately half the patients (48.3%) who had been randomly assigned to imatinib completed study treatment with imatinib, and 82.8% had a complete cytogenetic response. Serious adverse events that were considered by the investigators to be related to imatinib were uncommon and most frequently occurred during the first year of treatment. CONCLUSIONS: Almost 11 years of follow-up showed that the efficacy of imatinib persisted over time and that long-term administration of imatinib was not associated with unacceptable cumulative or late toxic effects. (Funded by Novartis Pharmaceuticals; IRIS ClinicalTrials.gov numbers, NCT00006343 and NCT00333840 .).

Comparable outcomes of patients eligible vs ineligible for SWOG leukemia studies.

Patients may be deemed ineligible for a clinical trial for reasons that do not directly impact efficacy or safety. We identified reasons for ineligibility and compared outcomes of ineligible with eligible patients treated on Southwest Oncology Group (SWOG) Leukemia Committee protocols. Patients enrolled in SWOG phase 2, 2/3, or 3 protocols open since 2005 were analyzed for eligibility status, reasons for ineligibility, baseline characteristics, Eastern Cooperative Oncology Group (ECOG) performance status (PS), serious adverse events (SAEs), complete remission (CR) status, and overall survival. A total of 2361 patients were enrolled in the 13 included studies. Of these, 247 (10%) were deemed ineligible; 78 were excluded from analyses, and 169 were included. Of the 169 included in analyses, 60% (101/169) were excluded due to missing baseline documentation. Baseline characteristics comparing ineligible to eligible patients were similar, with the exception of ECOG PS for S0325 (P = .02) and S0530 (P = .002). In multivariable analyses, neither the proportion of patients with ECOG PS ≥ 2 (P = .12) nor the rate of grade 5 SAEs (P = .62) differed between groups. There was no difference in survival between eligible and ineligible patients (P = .25), and CR rates were similar, with the exception of S0325 (P < .001) and S0703 (P = .004). The findings of this study suggest that nonessential eligibility criteria can be less restrictive, thus expanding patient enrollment and avoiding protocol deviations. The clinical trials included in this study were registered at www.clincialtrials.gov as #NCT00085709, #NCT00066794, #NCT00070499, #NCT00109837, #NCT00093418, #NCT00492856, #NCT00337168, #NCT00352365, #NCT00658814, #NCT00792948, #NCT00945815, #NCT00840177, and #NCT01522976.

Illuminating novel biological aspects and potential new therapeutic approaches for chronic myeloproliferative malignancies.

This review reflects the presentations and discussion at the 14th post-American Society of Hematology (ASH) International Workshop on Chronic Myeloproliferative Malignancies, which took place on the December 10 and 11, 2019, immediately after the 61st ASH Annual Meeting in Orlando, Florida. Rather than present a resume of the proceedings, we address some of the topical translational science research and clinically relevant topics in detail. We consider how recent studies using single-cell genomics and other molecular methods reveal novel aspects of hematopoiesis which in turn raise the possibility of new therapeutic approaches for patients with myeloproliferative neoplasms (MPNs). We discuss how alternative therapies could benefit patients with chronic myeloid leukemia who develop BCR-ABL1 mutant subclones following ABL1-tyrosine kinase inhibitor therapy. In MPNs, we focus on efforts beyond JAK-STAT and the merits of integrating activin receptor ligand traps, interferon-α, and allografting in the current treatment algorithm for patients with myelofibrosis.

Phase I/II multisite trial of optimally dosed clofarabine and low-dose TBI for hematopoietic cell transplantation in acute myeloid leukemia.

Clofarabine is an immunosuppressive purine nucleoside analog that may have better anti-leukemic activity than fludarabine. We performed a prospective phase I/II multisite trial of clofarabine with 2 Gy total body irradiation as non-myeloablative conditioning for allogeneic hematopoietic cell transplantation in adults with acute myeloid leukemia who were unfit for more intense regimens. Our main objective was to improve the 6-month relapse rate following non-myeloablative conditioning, while maintaining historic rates of non-relapse mortality (NRM) and engraftment. Forty-four patients, 53 to 74 (median: 69) years, were treated with clofarabine at 150 to 250 mg/m2 , of whom 36 were treated at the maximum protocol-specified dose. One patient developed multifactorial acute kidney injury and another developed multiorgan failure, but no other grade 3 to 5 non-hematologic toxicities were observed. All patients fully engrafted. The 6-month relapse rate was 16% (95% CI, 5%-27%) among all patients and 14% (95% CI, 3%-26%) among high-risk patients treated at the maximum dose, meeting the pre-specified primary efficacy endpoint. Overall survival was 55% (95% CI, 40%-70%) and leukemia-free survival was 52% (95% CI, 37%-67%) at 2 years. Compared to a historical high-risk cohort treated with the combination of fludarabine at 90 mg/m2 and 2 Gy TBI, protocol patients treated with the clofarabine-TBI regimen had lower rates of overall mortality (HR of 0.50, 95% CI, 0.28-0.91), disease progression or death (HR 0.48, 95% CI, 0.27-0.85), and morphologic relapse (HR 0.30, 95% CI, 0.13-0.69), and comparable NRM (HR 0.85, 95% CI 0.36-2.00). The combination of clofarabine with TBI warrants further investigation in patients with high-risk AML.

A Fluorescence-Activated Single-Droplet Dispenser for High Accuracy Single-Droplet and Single-Cell Sorting and Dispensing.

The ability to sort and dispense droplets accurately is essential to droplet-based single-cell analysis. Here, we describe a fluorescence-activated single-droplet dispenser (FASD) that is analogous to a conventional fluorescence-activated cell sorter, but sorts droplets containing single cells within an oil emulsion. The FASD system uses cytometric detection and electrohydrodynamic actuation-based single-droplet manipulation, allowing droplet isolation and dispensing with high efficiency and accuracy. The system is compatible with multiwell plates and can be integrated with existing microfluidic devices and large-scale screening systems. By enabling sorting based on single-cell reactions such as PCR, this platform will help expand the basis of cell sorting from mainly protein biomarkers to nucleic acid sequences and secreted biomolecules.