David M. Ross

Limited clinical value of regular bone marrow cytogenetic analysis in imatinib-treated chronic phase CML patients monitored by RQ-PCR for BCR-ABL

Real-time quantitative polymerase chain reaction (PCR) for BCR-ABL mRNA in the peripheral blood (RQ-PCR) provides an accurate and reliable measure of response to therapy in chronic myeloid leukaemia (CML). We wanted to determine in what circumstances additional clinically relevant information was provided by simultaneous cytogenetic analysis in RQ-PCR monitored patients receiving imatinib treatment. We analysed 828 simultaneous RQ-PCR and bone marrow cytogenetic analyses from 183 patients with chronic phase CML with a median follow-up of 20 months. Cytogenetic progression was defined as Philadelphia (Ph)-positive clonal evolution, loss of complete cytogenetic response or an increase of ⩾20% Ph-positive cells. Cytogenetic progression occurred in 24/183 (13%) patients. At the time of cytogenetic progression, none of the 24 patients had a major molecular response (MMR;⩾3-log reduction in BCR-ABL from standardised baseline). There were 320 RQ-PCR results from 95 patients indicating MMR. No abnormality was detected in any of the corresponding cytogenetic analyses. A policy of regular RQ-PCR monitoring with cytogenetic analysis targetted only to patients who have not achieved, or have lost MMR would represent a rational approach to monitoring and spare most patients the discomfort of multiple marrow aspirates. This approach depends upon availability of an accurate, reproducible RQ-PCR assay with ongoing quality assurance.

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%).

A tale of two siblings: two cases of AML arising from a single pre-leukemic DNMT3A mutant clone.

A tale of two siblings: two cases of AML arising from a single pre-leukemic DNMT3A mutant clone

Vosaroxin is a novel topoisomerase-II inhibitor with efficacy in relapsed and refractory acute myeloid leukaemia

Introduction: Vosaroxin is a first-in-class anti-cancer quinolone that inhibits topoisomerase-II leading to cell cycle arrest and apoptosis. It has shown efficacy in a range of solid organ and haematopoietic tumours in vitro, and several clinical trials are underway or completed in the field of Acute Myeloid Leukaemia (AML). The treatment of relapsed and refractory AML is a clinical challenge, where long-term survival is rare without allogeneic haematopoietic stem cell transplantation. Areas covered: We review the data from the published clinical trials of vosaroxin, including the recently presented Phase III VALOR study. In combination with intermediate dose cytarabine, vosaroxin almost doubled complete response (CR) rates in relapsed and refractory AML compared with cytarabine alone, and prolonged median survival by 1.4 months. Expert opinion: Vosaroxin is a promising new agent in the treatment of AML, with the potential to improve CR rates in a high-risk group of patients with relapsed and refractory AML. However, higher CR rates have been associated with higher rates of treatment-related morbidity and mortality, especially in elderly/unfit patients. Maximising the potential of vosaroxin will therefore require the identification of patients most likely to benefit from vosaroxin-containing combination regimens.

Reply to ‘What do we mean by sensitivity when we talk about detecting minimal residual disease?’ by Steinbach and Debatin

Reply to ‘What do we mean by sensitivity when we talk about detecting minimal residual disease?’ by Steinbach and Debatin

Delayed diagnosis leading to accelerated-phase chronic eosinophilic leukemia due to a cytogenetically cryptic, imatinib-responsive TNIP1-PDFGRB fusion gene.

Delayed diagnosis leading to accelerated-phase chronic eosinophilic leukemia due to a cytogenetically cryptic, imatinib-responsive TNIP1 – PDFGRB fusion gene

A case‐based discussion of clinical problems in the management of patients treated with ruxolitinib for myelofibrosis

Ruxolitinib is a dual janus kinase 1 (JAK1)/JAK2 inhibitor used to treat splenomegaly and symptoms associated with myelofibrosis (MF). Current therapeutic options for symptomatic MF include supportive care, myelosuppressive therapy (such as hydroxycarbamide) and janus kinase (JAK) inhibitors (in particular ruxolitinib). Allogeneic stem cell transplantation remains the only potentially curative treatment for MF, and younger transplant‐eligible patients should still be considered for allogeneic stem cell transplantation; however, this is applicable only to a small proportion of patients. There is now increasing and extensive experience of the efficacy and safety of ruxolitinib in MF, both in clinical trials and in ‘real‐world’ practice. The drug has been shown to be of benefit in intermediate‐1 risk patients with symptomatic splenomegaly or other MF‐related symptoms, and higher risk disease. Optimal use of the drug is required to maximise clinical benefit, requiring an understanding of the balance between dose‐dependent responses and dose‐limiting toxicities. There is also increasing experience in the use of ruxolitinib in the pre‐transplantation setting. This paper aims to utilise several ‘real‐life’ cases to illustrate several strategies that may help to optimise clinical practice.

Red cell alloimmunization is associated with development of autoantibodies and increased red cell transfusion requirements in myelodysplastic syndrome

Up to 90% of patients with a myelodysplastic syndrome require red blood cell transfusion; nevertheless, comprehensive data on red cell alloimmunization in such patients are limited. This study evaluates the incidence and clinical impact of red cell alloimmunization in a large cohort of patients with myelodysplastic syndrome registered in the statewide South Australian-MDS registry. The median age of the 817 patients studied was 73 years, and 66% were male. The cumulative incidence of alloimmunization was 11%. Disease-modifying therapy was associated with a lower risk of alloimmunization while alloimmunization was significantly higher in patients with a revised International Prognostic Scoring System classification of Very Low, Low or Intermediate risk compared to those with a High or Very High risk (P=0.03). Alloantibodies were most commonly directed against antigens in the Rh (54%) and Kell (24%) systems. Multiple alloantibodies were present in 49% of alloimmunized patients. Although 73% of alloimmunized patients developed alloantibodies during the period in which they received their first 20 red cell units, the total number of units transfused was significantly higher in alloimmunized patients than in non-alloimmunized patients (90±100 versus 30±52; P<0.0001). In individual patients, red cell transfusion intensity increased significantly following alloimmunization (2.8±1.3 versus 4.1±2.0; P<0.0001). A significantly higher proportion of alloimmunized patients than non-alloimmunized patients had detectable autoantibodies (65% versus 18%; P<0.0001) and the majority of autoantibodies were detected within a short period of alloimmunization. In conclusion, this study characterizes alloimmunization in a large cohort of patients with myelodysplastic syndrome and demonstrates a signficant increase in red cell transfusion requirements following alloimmunization, most probably due to development of additional alloantibodies and autoantibodies, resulting in subclinical/clinical hemolysis. Strategies to mitigate alloimmunization risk are critical for optimizing red cell transfusion support.

Discontinuation of Therapy and Treatment-Free Remission in CML

Tyrosine kinase inhibitor (TKI) treatment of chronic myeloid leukaemia (CML) has resulted in a life expectancy comparable to that of the general population for many individuals. This has led patients and clinicians to question whether, after a sustained period of deep molecular response, it might one day be possible to discontinue the TKI. A sustained molecular response without the need for ongoing treatment is referred to as a treatment-free remission (TFR). TFR has many potential advantages: patients in TFR may be free of chronic TKI toxicities that affect quality of life, and they may avoid the potential for late emerging toxicities (e.g. vascular events with nilotinib, pulmonary complications with dasatinib). It is imperative that young women with CML stop TKI prior to pregnancy due to the risk of teratogenesis. This can be achieved most safely for the mother and the baby if TFR has already been established. TFR reduces the considerable economic burden of long-term drug provision and improves the cost-effectiveness of the treatment. In this chapter, we review the clinical and biological data relevant to the topic of treatment discontinuation.

Abstract 1881: The microtubule-disrupting drug BNC105 is a potent inducer of apoptosis in AML patient samples

BNC105 is a phase II potent and highly selective disruptor of tumor microvasculature that causes the rapid onset of hypoxia and necrosis in solid tumors. BNC105 targets the colchicine-binding site on tubulin, causing chronic disruption of adhesion molecules, and was developed to be best-in-class with high specificity to actively dividing cells. It has one of the largest therapeutic windows of its class and has been shown to have direct cytotoxic activity on tumor cells. It is this highly tumor-specific mechanism of action that has positioned BNC105 as a therapeutic with high potential in the hematologic cancer setting. Previous studies of BNC105 have shown that treatment with BNC105 results in the activation of c-Jun N-terminal kinase (JNK), phosphorylation of ATF2, and the induction of ATF3 and Noxa, leading to acute apoptosis in chronic lymphocytic leukemia (CLL) cells. These findings led to the commencement of a phase 1/2 trial of BNC105 in patients with CLL. The present study was designed to investigate the effect of BNC105 treatment on acute myeloid leukemia (AML), a disease that currently has limited treatment options. To assess the utility of BNC105 therapy in this setting, six AML cell lines representing different subtypes, including the high-risk FLT3-ITD subtype, were initially used in proliferation and cytotoxicity assays. The production of reactive oxygen species (ROS), cell cycle distribution and cell signaling by Western blot were all assessed after treatment. All tested AML cell lines were highly sensitive to treatment with BNC105 with an IC 50 =0.2nM to 1.3nM after 48 hours treatment. Analysis of apoptosis induction revealed cell line-specific effects; however, a consistent dose-dependent increase in phosphorylation of JNK was observed across all cell lines. AML patient samples obtained from the South Australian Cancer Research Biobank (SACRB) were exposed to BNC105 at clinically relevant doses for up to 72 hours and cellular viability and apoptosis induction were assessed by Annexin V/ 7AAD staining and caspase 3 and 7 activation measured. BNC105 induced caspase activity and significantly decreased viability in a dose- and time-dependent manner, including the FLT3 mutant subtype patient samples. In comparison, bone marrow mononuclear cells from healthy controls were much less affected by BNC105. Effects of BNC105 on the leukemic stem cell (LSC) phenotype population were also investigated. The LSC-containing population, measured by CD34/CD38 and GPR56 or CD93 staining, was targeted by BNC105 in all AML patient samples tested. These results suggest that AML cells can be directly targeted by BNC105 at clinically relevant concentrations and hence further clinical investigation of BNC105 is warranted for AML treatment in a patient population with high unmet need. Citation Format: Daniel J. Inglis, Debora A. Casolari, Tran Nguyen, Donna M. Beaumont, Nicole L. Wittwer, David Ross, Richard D9Andrea, Tina C. Lavranos. The microtubule-disrupting drug BNC105 is a potent inducer of apoptosis in AML patient samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1881.