European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia.

The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR.

Treatment-free remission following frontline nilotinib in patients with chronic myeloid leukemia in chronic phase: results from the ENESTfreedom study.

The single-arm, phase 2 ENESTfreedom trial assessed the potential for treatment-free remission (TFR; i.e., the ability to maintain a molecular response after stopping therapy) following frontline nilotinib treatment. Patients with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase with MR4.5 (BCR-ABL1⩽0.0032% on the International Scale (BCR-ABL1IS)) and ⩾2 years of frontline nilotinib therapy were enrolled. Patients with sustained deep molecular response during the 1-year nilotinib consolidation phase were eligible to stop treatment and enter the TFR phase. Patients with loss of major molecular response (MMR; BCR-ABL1IS⩽0.1%) during the TFR phase reinitiated nilotinib. In total, 215 patients entered the consolidation phase, of whom 190 entered the TFR phase. The median duration of nilotinib before stopping treatment was 43.5 months. At 48 weeks after stopping nilotinib, 98 patients (51.6%; 95% confidence interval, 44.2-58.9%) remained in MMR or better (primary end point). Of the 86 patients who restarted nilotinib in the treatment reinitiation phase after loss of MMR, 98.8% and 88.4%, respectively, regained MMR and MR4.5 by the data cutoff date. Consistent with prior reports of imatinib-treated patients, musculoskeletal pain-related events were reported in 24.7% of patients in the TFR phase (consolidation phase, 16.3%).

Pre- and post-transplant quantification of measurable ('minimal') residual disease via multiparameter flow cytometry in adult acute myeloid leukemia.

Measurable ('minimal') residual disease (MRD) before or after hematopoietic cell transplantation (HCT) identifies adults with AML at risk of poor outcomes. Here, we studied whether peri-transplant MRD dynamics can refine risk assessment. We analyzed 279 adults receiving myeloablative allogeneic HCT in first or second remission who survived at least 35 days and underwent 10-color multiparametric flow cytometry (MFC) analyses of marrow aspirates before and 28±7 days after transplantation. MFC-detectable MRD before (n=63) or after (n=16) transplantation identified patients with high relapse risk and poor survival. Forty-nine patients cleared MRD with HCT conditioning, whereas two patients developed new evidence of disease. The 214 MRD(neg)/MRD(neg) patients had excellent outcomes, whereas both MRD(neg)/MRD(pos) patients died within 100 days following transplantation. For patients with pre-HCT MRD, outcomes were poor regardless of post-HCT MRD status, although survival beyond 3 years was only observed among the 58 patients with decreasing but not the seven patients with increasing peri-HCT MRD levels. In multivariable models, pre-HCT but not post-HCT MRD was independently associated with overall survival and risk of relapse. These data indicate that MRD(pos) patients before transplantation have a high relapse risk regardless of whether or not they clear MFC-detectable disease with conditioning and should be considered for pre-emptive therapeutic strategies.

Microfluidics for single-cell genetic analysis.

The ability to correlate single-cell genetic information to cellular phenotypes will provide the kind of detailed insight into human physiology and disease pathways that is not possible to infer from bulk cell analysis. Microfluidic technologies are attractive for single-cell manipulation due to precise handling and low risk of contamination. Additionally, microfluidic single-cell techniques can allow for high-throughput and detailed genetic analyses that increase accuracy and decrease reagent cost compared to bulk techniques. Incorporating these microfluidic platforms into research and clinical laboratory workflows can fill an unmet need in biology, delivering the highly accurate, highly informative data necessary to develop new therapies and monitor patient outcomes. In this perspective, we describe the current and potential future uses of microfluidics at all stages of single-cell genetic analysis, including cell enrichment and capture, single-cell compartmentalization and manipulation, and detection and analyses.

Nilotinib in imatinib-resistant or imatinib-intolerant patients with chronic myeloid leukemia in chronic phase: 48-month follow-up results of a phase II study.

Nilotinib (Tasigna) is a BCR-ABL1 tyrosine kinase inhibitor approved for the treatment of patients with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase (CML-CP) who are newly diagnosed or intolerant of or resistant to imatinib. The 48-month follow-up data for patients with CML-CP treated with nilotinib after imatinib resistance or intolerance on an international phase II study were analyzed. Overall, 59% of patients achieved major cytogenetic response; 45% achieved complete cytogenetic response while on study. The estimated rate of overall survival (OS) and progression-free survival (PFS) at 48 months was 78% and 57%, respectively. Deeper levels of molecular responses at 3 and 6 months were highly positively correlated with long-term outcomes, including PFS and OS at 48 months. Of the 321 patients initially enrolled in the study, 98 (31%) were treated for at least 48 months. Discontinuations were primarily due to disease progression (30%) or adverse events (21%). Nilotinib is safe and effective for long-term use in responding patients with CML-CP who are intolerant of or resistant to imatinib. Further significant improvements in therapy are required for patients who are resistant or intolerant to imatinib.

Prediction of outcomes in patients with Ph+ chronic myeloid leukemia in chronic phase treated with nilotinib after imatinib resistance/intolerance.

The purpose was to assess predictive factors for outcome in patients with chronic myeloid leukemia (CML) in chronic phase (CML-CP) treated with nilotinib after imatinib failure. Imatinib-resistant and -intolerant patients with CML-CP (n=321) were treated with nilotinib 400 mg twice daily. Of 19 baseline patient and disease characteristics and two response end points analyzed, 10 independent prognostic factors were associated with progression-free survival (PFS). In the multivariate analysis, major cytogenetic response (MCyR) within 12 months, baseline hemoglobin ≥ 120 g/l, baseline basophils <4%, and absence of baseline mutations with low sensitivity to nilotinib were associated with PFS. A prognostic score was created to stratify patients into five groups (best group: 0 of 3 unfavorable risk factors and MCyR by 12 months; worst group: 3 of 3 unfavorable risk factors and no MCyR by 12 months). Estimated 24-month PFS rates were 90%, 79%, 67% and 37% for patients with prognostic scores of 0, 1, 2 and 3, respectively, (no patients with score of 4). Even in the presence of poor disease characteristics, nilotinib provided significant clinical benefit in patients with imatinib-resistant or -intolerant CML. This system may yield insight on the prognosis of patients.

Predicting relapse prior to transplantation in chronic myeloid leukemia by integrating expert knowledge and expression data.

MOTIVATION: Selecting a small number of signature genes for accurate classification of samples is essential for the development of diagnostic tests. However, many genes are highly correlated in gene expression data, and hence, many possible sets of genes are potential classifiers. Because treatment outcomes are poor in advanced chronic myeloid leukemia (CML), we hypothesized that expression of classifiers of advanced phase CML when detected in early CML [chronic phase (CP) CML], correlates with subsequent poorer therapeutic outcome. RESULTS: We developed a method that integrates gene expression data with expert knowledge and predicted functional relationships using iterative Bayesian model averaging. Applying our integrated method to CML, we identified small sets of signature genes that are highly predictive of disease phases and that are more robust and stable than using expression data alone. The accuracy of our algorithm was evaluated using cross-validation on the gene expression data. We then tested the hypothesis that gene sets associated with advanced phase CML would predict relapse after allogeneic transplantation in 176 independent CP CML cases. Our gene signatures of advanced phase CML are predictive of relapse even after adjustment for known risk factors associated with transplant outcomes.

Molecular alterations of the IDH1 gene in AML: a Children's Oncology Group and Southwest Oncology Group study.

Recent whole-genome sequencing efforts led to the identification of IDH1(R132) mutations in acute myeloid leukemia (AML) patients. We studied the prevalence and clinical implications of IDH1 genomic alterations in pediatric and adult AML. Diagnostic DNA from 531 AML patients treated on Children's Oncology Group trial COG-AAML03P1 (N=257), and Southwest Oncology Group trials SWOG-9031, SWOG-9333 and SWOG-9500 (N=274), were tested for IDH1 mutations. Codon R132 mutations were absent in the pediatric cohort, but were found in 12 of 274 adult patients (4.4%, 95% CI 2.3-7.5). IDH1(R132) mutations occurred most commonly in patients with normal karyotype, and those with FLT3/ITD and NPMc mutations. Patients with IDH1(R132) mutations trended toward higher median diagnostic white blood cell counts (59.2 x 10(9) vs 29.1 x 10(9) per liter, P=0.19) than those without mutations, but the two groups did not differ significantly in age, bone marrow blast percentage, overall survival or relapse-free survival. Eleven patients (2.1%) harbored a novel V71I sequence alteration, which was found to be a germ-line polymorphism. IDH1 mutations were not detected in pediatric AML, and are uncommon in adult AML.

Six-year follow-up of patients receiving imatinib for the first-line treatment of chronic myeloid leukemia.

Imatinib mesylate is considered standard of care for first-line treatment of chronic phase chronic myeloid leukemia (CML-CP). In the phase III, randomized, open-label International Randomized Study of Interferon vs STI571 (IRIS) trial, previously untreated CML-CP patients were randomized to imatinib (n=553) or interferon-alpha (IFN) plus cytarabine (n=553). This 6-year update focuses on patients randomized to receive imatinib as first-line therapy for newly diagnosed CML-CP. During the sixth year of study treatment, there were no reports of disease progression to accelerated phase (AP) or blast crisis (BC). The toxicity profile was unchanged. The cumulative best complete cytogenetic response (CCyR) rate was 82%; 63% of all patients randomized to receive imatinib and still on study treatment showed CCyR at last assessment. The estimated event-free survival at 6 years was 83%, and the estimated rate of freedom from progression to AP and BC was 93%. The estimated overall survival was 88% -- or 95% when only CML-related deaths were considered. This 6-year update of IRIS underscores the efficacy and safety of imatinib as first-line therapy for patients with CML.

Efficacy and safety of dasatinib in imatinib-resistant or -intolerant patients with chronic myeloid leukemia in blast phase.

Dasatinib is an inhibitor of BCR-ABL and SRC-family kinases for patients with imatinib-resistant or -intolerant chronic myelogenous leukemia (CML). In this international phase II trial, dasatinib was administered orally (70 mg twice daily) to patients with myeloid blast phase (MBP, n=109) or lymphoid blast phase (LBP, n=48) CML. After a minimum follow-up of 12 months (range 0.03-20.7 months), major hematologic responses were induced in 34% (MBP-CML) and 35% (LBP-CML) of patients. Major cytogenetic responses were attained in 33% (MBP-CML) and 52% (LBP-CML) of patients and complete cytogenetic responses were attained in 26 and 46%, respectively. Median progression-free survival was 6.7 (MBP-CML) and 3.0 (LBP-CML) months. Median overall survival was 11.8 (MBP-CML) and 5.3 (LBP-CML) months. Overall, dasatinib had acceptable tolerability. Fluid retention events were more frequent in the MBP-CML than the LBP-CML cohort: pleural effusion occurred in 36 and 13% (all grades) and 15 and 6% (grades 3/4), respectively. Other non-hematologic side effects were primarily grade 1/2; grade 3/4 events were recorded in

The detection and significance of minimal residual disease in acute and chronic leukemia.

Minimal residual disease (MRD) can be detected in many patients with leukemia who have achieved complete remission as defined by conventional pathology examination. The detection of MRD, be it by flow cytometry or by polymerase chain reaction assays, has now been found to be associated with subsequent relapses in most leukemia subtypes, either following chemotherapy or following hematopoietic stem cell transplantation. These assays are now increasingly used in clinical trial design to optimize therapy and provide a novel way to assess treatment efficacy.

Hematopoietic cell transplantation from HLA-identical sibling donors after low-dose radiation-based conditioning for treatment of CML.

A total of 24 patients (median age 58; range, 27-71 years) with chronic myeloid leukemia (CML) in first chronic (CP1) (n=14), second chronic (n=4), or accelerated phase (n=6) who were not candidates for conventional hematopoietic cell transplantation (HCT), received nonmyeloablative HCT from HLA-matched siblings a median of 28.5 (range, 11-271) months after diagnosis. They were conditioned with 2 Gy total body irradiation (TBI) alone (n=8) or combined with fludarabine, 90 mg/m(2) (n=16). Postgrafting immunosuppression included cyclosporine and mycophenolate mofetil. All patients initially engrafted. However, 4 of 8 patients not given fludarabine experienced nonfatal rejection while all others had sustained engraftment. With a median follow-up of 36 (range, 4-49) months, 13 of 24 patients (54%) were alive and in complete remission. There were five (21%) deaths from nonrelapse mortality, one (4%) during the first 100 days after transplant. The proportions of grade II, III, and IV acute GVHD were 38, 4, and 8%, respectively. The 2-year estimate of chronic GVHD was 32%. The 2-year survival estimates for patients in CP1 (n=14) and beyond CP1 (n=10) were 70 and 56%, respectively. This study shows encouraging remission rates for patients with CML not eligible for conventional allografting.

A distinctive nuclear morphology in acute myeloid leukemia is strongly associated with loss of HLA-DR expression and FLT3 internal tandem duplication.

In a 5-year survey of nonpromyelocytic/nonmonocytic acute myeloid leukemias (AMLs) diagnosed in the University of Washington Hematopathology Laboratory, we identified 19 cases containing distinctive, cup-like nuclear indentation in 10% or more of the blasts ('AML-cuplike'). Fourteen of these cases (74%) demonstrated near-complete loss of HLA-DR expression, while the other five cases showed partial loss of HLA-DR. A total of 16 of the cases (84%) demonstrated internal tandem duplication (ITD) of the Flt3 gene. When compared to a selected set of AMLs lacking this nuclear morphology, AML-cuplike was significantly more likely to lack HLA-DR and CD34 expression, to express CD123 without CD133, to have a normal karyotype, and to harbor the Flt3 ITD. To characterize AML-cuplike in an unselected series of AMLs, we analyzed 42 consecutive nonpromyelocytic/nonmonocytic AMLs diagnosed in our laboratory during a 6-month period in 2002. Strikingly, in this unselected series, there was a statistically significant coincidence of invaginated nuclear morphology, loss of HLA-DR, and presence of the Flt3 ITD beyond that expected if these three features were unrelated, suggesting that AMLs with these three features may represent a distinct AML subset.

Quantitative, real-time polymerase chain reactions for FLT3 internal tandem duplications are highly sensitive and specific.

Internal tandem duplications (ITDs) of the FLT3 gene occur in approximately 20-30% of acute myeloid leukemia (AML) patients. We investigated if FLT3 ITDs could be used as minimal residual disease (MRD) markers for AML patients. Patient-specific polymerase chain reaction (PCR) assays for FLT3 ITDs were developed for four AML samples that contained FLT3 ITDs of varying size and location. The real-time, quantitative PCR assays for FLT3 ITDs were highly sensitive and specific, detecting between 0.01 and 0.001% of FLT3 ITD positive DNA in a background of 1 microg of normal bone marrow DNA. Our findings suggest that FLT3 ITDs can be used as molecular markers for MRD in patients with AML.

The significance of bcr-abl molecular detection in chronic myeloid leukemia patients "late," 18 months or more after transplantation.

The bcr-abl chimeric messenger RNA is frequently detected in chronic myeloid leukemia (CML) patients after bone marrow transplantation. It was previously reported that the relapse risk of bcr-abl detection 6 to 12 months after transplantation was greater than 40%. This risk decreased as the time between transplantation and detection increased. To further define the relapse risk associated with bcr-abl molecular detection in "late" CML survivors, 379 consecutive CML patients alive at 18 months after transplantation or later were studied. Ninety of 379 patients (24%) had at least one positive bcr-abl test 18 months after transplantation or later; 13 of 90 bcr-abl-positive patients (14%) and 3 of 289 bcr-abl-negative patients (1.0%) relapsed. The median time from bcr-abl detection to relapse was 916 days (range, 251-2654 days). The hazard ratio of relapse associated with bcr-abl detection was 19.2 (P <.0001). The stage of disease, chronic graft-versus-host disease, and the donor type did not alter the association between bcr-abl and relapse. Quantification of bcr-abl was performed on 344 samples from 85 bcr-abl-positive patients by means of a real-time quantitative reverse transcriptase-polymerase chain reaction assay. The median bcr-abl change of patients who relapsed was significantly greater than those that remained in remission (P =.002). The median bcr-abl level at relapse was 40 443 bcr-abl copies per microg RNA (range, 960-299 552). Of 73 bcr-abl-positive patients who failed to relapse, 69% had only one positive test at a median of 24 copies bcr-abl per microg RNA. The detection of bcr-abl is common following transplantation. The prognostic significance of a qualitative bcr-abl can be refined by quantitative assays and thus may target patients who would benefit from early intervention.

FLT3, RAS, and TP53 mutations in elderly patients with acute myeloid leukemia.

The prevalence and significance of genetic abnormalities in older patients with acute myeloid leukemia (AML) are unknown. Polymerase chain reactions and single-stranded conformational polymorphism analyses were used to examine 140 elderly AML patients enrolled in the Southwest Oncology Group study 9031 for FLT3, RAS, and TP53 mutations, which were found in 34%, 19%, and 9% of patients, respectively. All but one of the FLT3 (46 of 47) mutations were internal tandem duplications (ITDs) within exons 11 and 12. In the remaining case, a novel internal tandem triplication was found in exon 11. FLT3 ITDs were associated with higher white blood cell counts, higher peripheral blast percentages, normal cytogenetics, and less disease resistance. All RAS mutations (28 of 28) were missense point mutations in codons 12, 13, or 61. RAS mutations were associated with lower peripheral blast and bone marrow blast percentages. Only 2 of 47 patients with FLT3 ITDs also had a RAS mutation, indicating a significant negative association between FLT3 and RAS mutations (P =.0013). Most TP53 mutations (11 of 12) were missense point mutations in exons 5 to 8 and were associated with abnormal cytogenetics, especially abnormalities in both chromosomes 5 and 7. FLT3 and RAS mutations were not associated with inferior clinical outcomes, but TP53 mutations were associated with a worse overall survival (median 1 versus 8 months, P =.0007). These results indicate that mutations in FLT3, RAS, or TP53 are common in older patients with AML and are associated with specific AML phenotypes as defined by laboratory values, cytogenetics, and clinical outcomes. (Blood. 2001;97:3589-3595)