Biallelic TET2 mutations confer sensitivity to 5'-azacitidine in acute myeloid leukemia.

Precision medicine can significantly improve outcomes for patients with cancer, but implementation requires comprehensive characterization of tumor cells to identify therapeutically exploitable vulnerabilities. Here, we describe somatic biallelic TET2 mutations in an elderly patient with acute myeloid leukemia (AML) that was chemoresistant to anthracycline and cytarabine but acutely sensitive to 5'-azacitidine (5'-Aza) hypomethylating monotherapy, resulting in long-term morphological remission. Given the role of TET2 as a regulator of genomic methylation, we hypothesized that mutant TET2 allele dosage affects response to 5'-Aza. Using an isogenic cell model system and an orthotopic mouse xenograft, we demonstrate that biallelic TET2 mutations confer sensitivity to 5'-Aza compared with cells with monoallelic mutations. Our data argue in favor of using hypomethylating agents for chemoresistant disease or as first-line therapy in patients with biallelic TET2-mutated AML and demonstrate the importance of considering mutant allele dosage in the implementation of precision medicine for patients with cancer.

Genome-wide association study identifies susceptibility loci for acute myeloid leukemia.

Acute myeloid leukemia (AML) is a hematological malignancy with an undefined heritable risk. Here we perform a meta-analysis of three genome-wide association studies, with replication in a fourth study, incorporating a total of 4018 AML cases and 10488 controls. We identify a genome-wide significant risk locus for AML at 11q13.2 (rs4930561; P = 2.15 × 10-8; KMT5B). We also identify a genome-wide significant risk locus for the cytogenetically normal AML sub-group (N = 1287) at 6p21.32 (rs3916765; P = 1.51 × 10-10; HLA). Our results inform on AML etiology and identify putative functional genes operating in histone methylation (KMT5B) and immune function (HLA).

Serum Flt3 ligand is a biomarker of progenitor cell mass and prognosis in acute myeloid leukemia.

Fms-like tyrosine kinase 3 (Flt3) is expressed on progenitor cells and acute myeloid leukemia (AML) blasts. Fms-like tyrosine kinase 3 ligand (Flt3L) is detectable during homeostasis and increases in hypoplasia due to genetic defects or treatment with cytoreductive agents. Conversely, Flt3+ AML is associated with depletion of Flt3L to undetectable levels. After induction chemotherapy, Flt3L is restored in patients entering complete remission (CR) but remains depressed in those with refractory disease. Weekly sampling reveals marked differences in the kinetics of Flt3L response during the first 6 weeks of treatment, proportionate to the clearance of blasts and cellularity of the bone marrow. In the UK NCRI AML17 trial, Flt3L was measured at day 26 in a subgroup of 140 patients with Flt3 mutation randomized to the tyrosine kinase inhibitor lestaurtinib or placebo. In these patients, attainment of CR was associated with higher Flt3L at day 26 (Mann-Whitney UP < .0001). Day 26 Flt3L was also associated with survival; Flt3L ≤291 pg/mL was associated with inferior event-free survival (EFS), and Flt3L >1185 pg/mL was associated with higher overall survival (OS; P = .0119). The separation of EFS and OS curves increased when minimal residual disease (MRD) status was combined with Flt3L measurement, and Flt3L retained a near-significant association with survival after adjusting for MRD in a proportional hazards model. Serial measurement of Flt3L in patients who had received a hematopoietic stem cell transplant for AML illustrates the potential value of monitoring Flt3L to identify relapse. Measurement of Flt3L is a noninvasive test with the potential to inform clinical decisions in patients with AML.

Inhibition of ATR acutely sensitizes acute myeloid leukemia cells to nucleoside analogs that target ribonucleotide reductase.

The ataxia telangiectasia and Rad3-related (ATR) protein kinase promotes cancer cell survival by signaling stalled replication forks generated by replication stress, a common feature of many cancers including acute myeloid leukemia (AML). Here we show that the antileukemic activity of the chemotherapeutic nucleoside analogs hydroxyurea and gemcitabine was significantly potentiated by ATR inhibition via a mechanism involving ribonucleotide reductase (RNR) abrogation and inhibition of replication fork progression. When administered in combination with gemcitabine, an inhibitor of the M1 RNR subunit, the ATR inhibitor VX-970, eradicated disseminated leukemia in an orthotopic mouse model, eliciting long-term survival and effective cure. These data identify a synergistic interaction between ATR inhibition and RNR loss that will inform the deployment of small molecule inhibitors for the treatment of AML and other hematologic malignancies.

Guidelines for the diagnosis and management of acute myeloid leukaemia in pregnancy.

Pregnant women should be managed by a multidisciplinary team that includes haematologists, obstetricians, neonatologists and anaesthetists (Grade 1C) As for non-pregnant patients, acute myeloid leukaemia (AML) should be diagnosed using the World Health Organization (WHO) classification (Grade 1A) Women diagnosed with AML in pregnancy should be treated without delay (Grade 1B) When the diagnosis of AML is made in the first trimester, a successful pregnancy outcome is unlikely and spontaneous pregnancy loss in this situation carries considerable risks for the mother. The reasons for and against elective termination should be discussed with the patient (Grade 2C) In the case of presentation beyond 32 weeks gestation, it may be reasonable to deliver the foetus prior to commencement of chemotherapy (Grade 2C) Between 24 and 32 weeks, risks of foetal chemotherapy exposure must be balanced against risks of prematurity following elective delivery at that stage of gestation (Grade 1C) The risk-benefit ratio must be carefully considered before using any drugs in pregnancy (Grade 1C) Where AML induction chemotherapy is delivered, a standard daunorubicin, cytarabine 3 + 10 schedule should be used (Grade 1B) Chemotherapy should be dosed according to actual body weight and adjustments made for weight changes during treatment (Grade 1C) Quinolones, tetracyclines and sulphonamide use should be avoided in pregnancy (Grade 1B) Amphotericin B or lipid derivatives are the antifungal of choice in pregnancy (Grade 2C) Cytomegalovirus (CMV)-negative blood products should be administered during pregnancy regardless of CMV serostatus (Grade 1B) A course of corticosteroids should be considered if delivery is anticipated between 24 and 35 weeks gestation, given over a 48-h period during the week prior to delivery (Grade 1A) Use of magnesium sulphate should be considered in the 24 h prior to delivery if this is before 30 weeks gestation (Grade 1A) Where possible, delivery should be planned for a time when the woman is at least 3 weeks post-chemotherapy to minimize risk of neonatal myelosuppression (Grade 1C) Planned delivery is easier to manage than spontaneous labour; induction of labour is usually advised (Grade 2C) Epidural analgesia should be avoided in a woman who is significantly thrombocytopenic (platelet count <80 × 10(9) /l) and/or neutropenic (white blood cell count <1 × 10(9) /l): (Grade 1C) Elective caesarean section should only be recommended for obstetric indications (Grade 2C) Antibiotics should be administered during and after premature rupture of membranes and delivery (Grade 1C).

An international approach to the treatment of Hodgkin's disease in the elderly: launch of the SHIELD study programme.

Utilising the Scotland and Newcastle Lymphoma Group population data for Hodgkin's disease (HD), collected over a 20-year period, it is evident that 20% of patients are over the age of 60 yr at diagnosis. Data from 674 patients are available. This group comprised 346 men and 328 women. Median follow-up was 9.5 yr. In total 361 patients had stage I/II disease. In this cohort overall response and complete response (CR) rates were 88% and 79%, respectively, for treated patients. Overall 308 patients had stage III/IV disease. Among treated patients in this cohort, overall and CR rates were 78% and 59%, respectively. Response data were missing for 26 patients with stage I/II disease and 43 patients with stage III/IV disease. The chlorambucil, vinblastine, procarbazine and prednisolone, mechlorethamine, vincristine, probarbazine and prednisolone and doxorubicin, bleomycin, vinblastine and decarbazine were the commonest chemotherapy regimens, in descending order of frequency, used to treat this cohort of patients. Outcome did not vary with these regimens. Thirty-four other chemotherapy combinations were used, some curative others palliative. These data and all other published studies confirm the need for a prospective, age-defined approach to HD in the elderly. Such an approach needs to be closely linked to issues of comorbidity, an assessment of frailness and the tailoring of specific protocols for the elderly to allow full dose delivery. The Study of Hodgkin Lymphoma In the Elderly/Lymphoma Database programme has now been launched and attempts to address these issues (http://www.shieldstudy.co.uk).