Ellin Berman

Leukaemogenesis induced by an activating β-catenin mutation in osteoblasts

Cells of the osteoblast lineage affect the homing and the number of long-term repopulating haematopoietic stem cells, haematopoietic stem cell mobilization and lineage determination and B cell lymphopoiesis. Osteoblasts were recently implicated in pre-leukaemic conditions in mice. However, a single genetic change in osteoblasts that can induce leukaemogenesis has not been shown. Here we show that an activating mutation of β-catenin in mouse osteoblasts alters the differentiation potential of myeloid and lymphoid progenitors leading to development of acute myeloid leukaemia with common chromosomal aberrations and cell autonomous progression. Activated β-catenin stimulates expression of the Notch ligand jagged 1 in osteoblasts. Subsequent activation of Notch signalling in haematopoietic stem cell progenitors induces the malignant changes. Genetic or pharmacological inhibition of Notch signalling ameliorates acute myeloid leukaemia and demonstrates the pathogenic role of the Notch pathway. In 38% of patients with myelodysplastic syndromes or acute myeloid leukaemia, increased β-catenin signalling and nuclear accumulation was identified in osteoblasts and these patients showed increased Notch signalling in haematopoietic cells. These findings demonstrate that genetic alterations in osteoblasts can induce acute myeloid leukaemia, identify molecular signals leading to this transformation and suggest a potential novel pharmacotherapeutic approach to acute myeloid leukaemia.

Phase I and II study of fludarabine phosphate in leukemia: therapeutic efficacy with delayed central nervous system toxicity.

Fludarabine phosphate (9-beta-D-arabinofuranosyl-2-fluoroadenine), a novel purine nucleoside, has demonstrated excellent preclinical antitumor activity and little toxicity in phase I clinical trials. We evaluated the clinical use of fludarabine given as a continuous intravenous (IV) infusion for remission induction in patients with relapsed or refractory leukemia. Thirty infusions were administered to 25 patients. At doses less than or equal to 125 mg/m2/d for five days, only three of 17 patients cleared their bone marrow of leukemic cells, and none achieved complete remission (CR). Nine patients received doses of 150 mg/m2/d for five days or 125 mg/m2/d for seven days. Four of these patients achieved CR (three patients with acute nonlymphoblastic leukemia (ANLL), one patient with acute lymphoblastic leukemia (ALL]. However, severe CNS toxicity was encountered in five patients at the two highest dose levels. Initial symptoms of neurotoxicity were delayed from 21 to 43 days after starting treatment and consisted of optic neuritis, cortical blindness, altered mental status, and generalized seizure. Only one patient regained visual and neurologic function; four other patients experienced progressive neurologic deterioration and died. Clinicopathologic evaluation suggested widespread, severe demyelination as the etiology of these reactions. We conclude that fludarabine is an effective drug for remission induction in acute leukemia. However, doses required to achieve CR are associated with unacceptable CNS toxicity. In view of its potent antileukemic activity, further evaluation of fludarabine at lower doses (less than or equal to 75 mg/m2/d for five days) may be warranted in combination with other chemotherapeutic agents for the treatment of patients with acute leukemia.

Vaccination with synthetic analog peptides derived from WT1 oncoprotein induces T-cell responses in patients with complete remission from acute myeloid leukemia

A pilot study was undertaken to assess the safety, activity, and immunogenicity of a polyvalent Wilms tumor gene 1 (WT1) peptide vaccine in patients with acute myeloid leukemia in complete remission but with molecular evidence of WT1 transcript. Patients received 6 vaccinations with 4 WT1 peptides (200 microg each) plus immune adjuvants over 12 weeks. Immune responses were evaluated by delayed-type hypersensitivity, CD4+ T-cell proliferation, CD3+ T-cell interferon-gamma release, and WT1 peptide tetramer staining. Of the 9 evaluable patients, 7 completed 6 vaccinations and WT1-specific T-cell responses were noted in 7 of 8 patients. Three patients who were HLA-A0201-positive showed significant increase in interferon-gamma-secreting cells and frequency of WT1 tetramer-positive CD8+ T cells. Three patients developed a delayed hypersensitivity reaction after vaccination. Definite related toxicities were minimal. With a mean follow-up of 30 plus or minus 8 months after diagnosis, median disease-free survival has not been reached. These preliminary data suggest that this polyvalent WT1 peptide vaccine can be administered safely to patients with a resulting immune response. Further studies are needed to establish the role of vaccination as viable postremission therapy for acute myeloid leukemia.

Cytarabine with high-dose mitoxantrone induces rapid complete remissions in adult acute lymphoblastic leukemia without the use of vincristine or prednisone.

PURPOSE To evaluate the efficacy and safety of a new induction regimen for adult acute lymphoblastic leukemia (ALL) that does not contain vincristine or corticosteroids. PATIENTS AND METHODS Thirty-seven adult patients with newly diagnosed ALL and lymphoblastic lymphoma were treated with a dose-intense induction regimen. This regimen was designed to increase the fraction of patients achieving an early complete remission (CR) in an attempt to increase long-term disease-free survival. The induction regimen was cytarabine (Ara-C) 3 g/m2/d for 5 days and mitoxantrone 80 mg/m2 as a single dose on day 3. Granulocyte colony-stimulating factor (G-CSF) 200 micrograms/ m2/d beginning on day 7 was used to promote early myeloid recovery. RESULTS There were 31 CRs (84%). Median time to CR was 34 days, median hospital stay was 28 days, and the median number of days with a neutrophil count less than 500/microL was 18. There were three patients with resistant disease who experienced treatment failure and three early deaths from sepsis. Four patients with Philadelphia chromosome-positive (Ph+) ALL achieved hematologic and cytogenetic CRs. CONCLUSION This dose-intense induction regimen produced a high incidence of CRs with acceptable toxicity without the use of vincristine or corticosteroids. Comparisons with our prior vincristine/prednisone-based induction regimen (the L-20 protocol) suggest that patients treated on the current study were more likely to achieve a CR and that they achieved this remission earlier than patients treated with a traditional four-drug (vincristine, prednisone, doxorubicin, and cyclophosphamide) induction regimen.

Phase 1/2 study to assess the safety, efficacy, and pharmacokinetics of barasertib (AZD1152) in patients with advanced acute myeloid leukemia

The primary objective of this 2-part phase 1/2 study was to determine the maximum-tolerated dose (MTD) of the potent and selective Aurora B kinase inhibitor barasertib (AZD1152) in patients with newly diagnosed or relapsed acute myeloid leukemia (AML). Part A determined the MTD of barasertib administered as a continuous 7-day infusion every 21 days. In part B, the efficacy of barasertib was evaluated at the MTD. In part A, 32 patients were treated with barasertib 50 mg (n = 3), 100 mg (n = 3), 200 mg (n = 3), 400 mg (n = 4), 800 mg (n = 7), 1200 mg (n = 6), and 1600 mg (n = 6). Dose-limiting toxicities (stomatitis/mucosal inflammation events) were reported in the 800 mg (n = 1), 1200 mg (n = 1), and 1600 mg (n = 2) groups. The MTD was defined as 1200 mg. In part B, 32 patients received barasertib 1200 mg. In each part of the study, 8 of 32 patients had a hematologic response according to Cheson AML criteria. The most commonly reported grade ≥ 3 events were febrile neutropenia (n = 24) and stomatitis/mucosal inflammation (n = 16). We concluded that the MTD of barasertib is 1200 mg in patients with relapsed or newly diagnosed AML. Toxicity was manageable and barasertib treatment resulted in an overall hematologic response rate of 25%. This study is registered at www.ClinicalTrials.gov as NCT00497991.

Inhibition of leukemia cell engraftment and disease progression in mice by osteoblasts

The bone marrow niche is thought to act as a permissive microenvironment required for emergence or progression of hematologic cancers. We hypothesized that osteoblasts, components of the niche involved in hematopoietic stem cell (HSC) function, influence the fate of leukemic blasts. We show that osteoblast numbers decrease by 55% in myelodysplasia and acute myeloid leukemia patients. Further, genetic depletion of osteoblasts in mouse models of acute leukemia increased circulating blasts and tumor engraftment in the marrow and spleen leading to higher tumor burden and shorter survival. Myelopoiesis increased and was coupled with a reduction in B lymphopoiesis and compromised erythropoiesis, suggesting that hematopoietic lineage/progression was altered. Treatment of mice with acute myeloid or lymphoblastic leukemia with a pharmacologic inhibitor of the synthesis of duodenal serotonin, a hormone suppressing osteoblast numbers, inhibited loss of osteoblasts. Maintenance of the osteoblast pool restored normal marrow function, reduced tumor burden, and prolonged survival. Leukemia prevention was attributable to maintenance of osteoblast numbers because inhibition of serotonin receptors alone in leukemic blasts did not affect leukemia progression. These results suggest that osteoblasts play a fundamental role in propagating leukemia in the marrow and may be a therapeutic target to induce hostility of the niche to leukemia blasts.

Reasons that patients with acute myelogenous leukemia do not undergo allogeneic bone marrow transplantation.

BACKGROUND Numerous reports suggest that allogeneic bone marrow transplantation prolongs the survival of adult patients with acute myelogenous leukemia (AML) in first remission. However, it is unclear how many such patients actually undergo this procedure. METHODS We reviewed the case records of 350 consecutive adult patients with AML treated with chemotherapy at a single institution from 1979 (when the policy of offering allogeneic transplantation to all such patients in first remission was introduced) through 1990. The criteria for exclusion before transplantation included age greater than 40 and, beginning in 1984, a diagnosis of acute promyelocytic leukemia. RESULTS One hundred forty-two patients (41 percent of the study population) were 40 years of age or under. HLA testing was performed for 120 of these patients (85 percent). Sixty-seven patients (47 percent) had an HLA-identical sibling as a potential donor. One hundred three patients (73 percent) entered remission during treatment according to one of five chemotherapy protocols. Of the 52 patients who both entered remission and had an HLA match, 30 underwent transplantation while they were in first remission. These 30 patients constituted 21 percent of all study patients 40 years old or under, 29 percent of all patients 40 or under who entered remission, 45 percent of all patients with an HLA match, 58 percent of all patients who had both a remission and a match, and 9 percent of all patients treated according to a protocol. Among patients with a match who did not undergo transplantation, those with primary refractory disease were the largest subgroup. CONCLUSIONS These findings suggest that allogeneic bone marrow transplantation is performed in less than 60 percent of adult patients with AML who are potentially eligible for the procedure.

A pilot vaccination trial of synthetic analog peptides derived from the BCR-ABL breakpoints in CML patients with minimal disease

A pilot vaccination trial of synthetic analog peptides derived from the BCR-ABL breakpoints in CML patients with minimal disease

FoxO1-dependent induction of acute myeloid leukemia by osteoblasts in mice.

Osteoblasts, the bone forming cells, affect self-renewal and expansion of hematopoietic stem cells (HSCs), as well as homing of healthy hematopoietic cells and tumor cells into the bone marrow. Constitutive activation of β-catenin in osteoblasts is sufficient to alter the differentiation potential of myeloid and lymphoid progenitors and to initiate the development of acute myeloid leukemia (AML) in mice. We show here that Notch1 is the receptor mediating the leukemogenic properties of osteoblast-activated β-catenin in HSCs. Moreover, using cell-specific gene inactivation mouse models, we show that FoxO1 expression in osteoblasts is required for and mediates the leukemogenic properties of β-catenin. At the molecular level, FoxO1 interacts with β-catenin in osteoblasts to induce expression of the Notch ligand, Jagged-1. Subsequent activation of Notch signaling in long-term repopulating HSC progenitors induces the leukemogenic transformation of HSCs and ultimately leads to the development of AML. These findings identify FoxO1 expressed in osteoblasts as a factor affecting hematopoiesis and provide a molecular mechanism whereby the FoxO1/activated β-catenin interaction results in AML. These observations support the notion that the bone marrow niche is an instigator of leukemia and raise the prospect that FoxO1 oncogenic properties may occur in other tissues.

Importance of long-term follow-up in evaluating treatment regimens for adults with acute lymphoblastic leukemia.

During the past 20 years, we have treated 250 previously untreated adults (greater than age 15 years) with acute lymphoblastic leukemia (ALL) with five successive multidrug protocols: L2, L10, L10M, L17/17M, and L20. The L10 and L10M protocols had the highest percentage of long-term (greater than 5 years) remissions (52% and 40% respectively) compared with the L2 and more recent protocols (24%-32%); this is partly attributable to a greater prevalence of adverse risk factors among the latter protocols. The overall long-term survival of the first 199 patients with minimum 3 years follow-up is now 31%, with 35% of the 163 patients achieving complete remission (CR) remaining free of relapse for greater than 5 years. The disease-free survival of the 163 patients reaches a plateau of 33% after 6 years. The percentages of patients subsequently relapsing after remaining in continuous CR for 1.5, 3, and 5 years are 42%, 28%, and 6%, respectively; no relapses have yet occurred after 6 years in this series. Postrelapse survival improved progressively with longer duration of first remission. The results of treatment in second or later remission with either chemotherapy or bone marrow transplantation (BMT) were unsatisfactory and there were only a few long-term survivors. Recently we have attempted to select patients at highest risk of early relapse for BMT in first remission, but the number of eligible patients actually having BMTs has been low for a variety of reasons, including early death, failure to reach CR, early relapse, patient refusal, or medical contraindications.(ABSTRACT TRUNCATED AT 250 WORDS)