CD34(+)/CD38(-) stem cells in chronic myeloid leukemia express Siglec-3 (CD33) and are responsive to the CD33-targeting drug gemtuzumab/ozogamicin

Background

CD33 is a well-known stem cell target in acute myeloid leukemia. So far, however, little is known about expression of CD33 on leukemic stem cells in chronic leukemias.

Design and Methods

We analyzed expression of CD33 in leukemic progenitors in chronic myeloid leukemia by multi-color flow cytometry and quantitative polymerase chain reaction. In addition, the effects of a CD33-targeting drug, gemtuzumab/ozogamicin, were examined.

Results

As assessed by flow cytometry, stem cell-enriched CD34⁺/CD38⁻/CD123⁺ leukemic cells expressed significantly higher levels of CD33 compared to normal CD34⁺/CD38⁻ stem cells. Moreover, highly enriched leukemic CD34⁺/CD38⁻ cells (>98% purity) displayed higher levels of CD33 mRNA. In chronic phase patients, CD33 was found to be expressed invariably on most or all stem cells, whereas in accelerated or blast phase of the disease, the levels of CD33 on stem cells varied from donor to donor. The MDR1 antigen, supposedly involved in resistance against ozogamicin, was not detectable on leukemic CD34⁺/CD38⁻ cells. Correspondingly, gemtuzumab/ozogamicin produced growth inhibition in leukemic progenitor cells in all patients tested. The effects of gemtuzumab/ozogamicin were dose-dependent, occurred at low concentrations, and were accompanied by apoptosis in suspension culture. Moreover, the drug was found to inhibit growth of leukemic cells in a colony assay and long-term culture-initiating cell assay. Finally, gemtuzumab/ozogamicin was found to synergize with nilotinib and bosutinib in inducing growth inhibition in leukemic cells.

Conclusions

CD33 is expressed abundantly on immature CD34⁺/CD38⁻ stem cells and may serve as a stem cell target in chronic myeloid leukemia.     

Non-myeloablative conditioning with allogeneic hematopoietic cell transplantation for the treatment of high-risk acute lymphoblastic leukemia

Background

Allogeneic hematopoietic cell transplantation is a potentially curative treatment for patients with acute lymphoblastic leukemia. However, the majority of older adults with acute lymphoblastic leukemia are not candidates for myeloablative conditioning regimens. A non-myeloablative preparative regimen is a reasonable treatment option for this group. We sought to determine the outcome of non-myeloablative conditioning and allogeneic transplantation in patients with high-risk acute lymphoblastic leukemia.

Design and Methods

Fifty-one patients (median age 56 years) underwent allogeneic hematopoietic cell transplantation from sibling or unrelated donors after fludarabine and 2 Gray total body irradiation. Twenty-five patients had Philadelphia chromosome-positive acute lymphoblastic leukemia. Eighteen of these patients received post-grafting imatinib.

Results

With a median follow-up of 43 months, the 3-year overall survival was 34%. The 3-year relapse/progression and non-relapse mortality rates were 40% and 28%, respectively. The cumulative incidences of grades II and III-IV acute graft-versus-host disease were 53% and 6%, respectively. The cumulative incidence of chronic graft-versus-host disease was 44%. Hematopoietic cell transplantation in first complete remission and post-grafting imatinib were associated with improved survival (P=0.005 and P=0.03, respectively). Three-year overall survival rates for patients with Philadelphia-negative acute lymphoblastic leukemia in first remission and beyond first remission were 52% and 8%, respectively. For patients with Philadelphia chromosome-positive acute lymphoblastic leukemia in first remission who received post-grafting imatinib, the 3-year overall survival rate was 62%; for the subgroup without evidence of minimal residual disease at transplantation, the overall survival was 73%.

Conclusions

For patients with high-risk acute lymphoblastic leukemia in first complete remission, non-myeloablative conditioning and allogeneic hematopoietic cell transplantation, with post-grafting imatinib for Philadelphia chromosome-positive disease, can result in favorable long-term survival. (Clinicaltrials.gov identifier: NCT0036738)     

ABC transporter A3 facilitates lysosomal sequestration of imatinib and modulates susceptibility of chronic myeloid leukemia cell lines to this drug

Background

Inhibition of BCR-ABL tyrosine kinase activity has evolved as a mainstay of therapy for patients with chronic myeloid leukemia. However, a fraction of leukemic cells persists under targeted therapy and can lead to disease progression on cessation of treatment.

Design and Methods

We analyzed bone marrow progenitor cells with the side population phenotype, and characterized the role of the intracellular ABC transporter A3 in imatinib detoxification.

Results

BCR-ABL-positive leukemic cells contribute to the side population cell compartment in untreated patients. Such leukemic side population cells, as well as CD34-positive progenitors from chronic myeloid leukemia samples, strongly express the intracellular ABCA3. Functionally, ABCA3 levels are critical for the susceptibility of chronic myeloid leukemia blast cell lines to specific BCR-ABL inhibition by imatinib. The transporter is localized in the limiting membrane of lysosomes and multivesicular bodies, and intracellular [¹⁴C]-labeled imatinib accumulates in such organelles. The lysosomal storage capacity increases with ABCA3 expression, thus regulating imatinib sequestration.

Conclusions

The intracellular ABC transporter A3 is expressed in chronic myeloid leukemia progenitor cells and may contribute to intrinsic imatinib resistance by facilitating lysosomal sequestration in chronic myeloid leukemia cells.     

CD8+ T-cell immunity against cancer-testis antigens develops following allogeneic stem cell transplantation and reveals a potential mechanism for the graft-versus-leukemia effect

Background

Allogeneic stem cell transplantation is associated with a powerful ‘graft-versus-leukemia’ effect that is generally considered to result from an alloreactive T-cell immune response. However, disease remission can also be observed after syngeneic transplantation and we investigated whether a T-cell immune response to cancer-testis antigens can be detected in patients in the post-transplant period.

Design and Methods

The T-cell immune response against cancer-testis antigens was studied in a cohort of 41 patients who underwent allogeneic stem cell transplantation for the management of acute myeloid leukemia or multiple myeloma. The cytokine secretion assay was combined with magnetic selection to allow detection of an interferon-γ-secreting T-cell response to a panel of cancer-testis antigen peptides.

Results

A cancer-testis antigen-specific CD8⁺ T-cell immune response was observed in the peripheral blood of five patients with an average magnitude of 0.045% of the CD8⁺ T-cell repertoire. Four of these patients had undergone reduced intensity conditioning transplantation with alemtuzumab for the treatment of acute myeloid leukemia and three remain in long-term remission. T-cell immunity was focused against peptides derived from MAGE proteins and was markedly increased within the bone marrow.

Conclusions

Functional cancer-testis antigen-specific CD8⁺ T-cell immune responses develop in the early period following reduced intensity allogeneic stem cell transplantation and are preferentially localized to bone marrow. These immune responses are likely to contribute to the cellular basis of the graft-versus-leukemia effect.     

Chronic phase chronic myeloid leukemia patients with low OCT-1 activity randomized to high-dose imatinib achieve better responses and have lower failure rates than those randomized to standard-dose imatinib

Background

The functional activity of the organic cation transporter 1 (OCT-1) protein (OCT-1 activity) is an excellent predictor of molecular response and progression-free survival in patients with newly diagnosed chronic phase chronic myeloid leukemia treated with imatinib as front-line therapy.

Design and Methods

In this study the predictive value of OCT-1 activity in patients treated with imatinib 400 mg/day or 800 mg/day was evaluated in relation to trough imatinib plasma levels assessed in 100 patients enrolled in the Tyrosine Kinase Inhibitor Optimization and Selectivity (TOPS) trial.

Results

The rate of major molecular responses by 24 months in patients on imatinib 400 mg/day was significantly higher in those with high OCT-1 activity than in those with low OCT-1 activity (low OCT-1 activity, 57% of patients; high OCT-1 activity, 100%; P<0.001); the corresponding difference in patients treated with imatinib 800 mg/day did not reach statistical significance (low OCT-1 activity, 68%; high OCT-1 activity, 95%; P=0.073). In addition, the combination of low trough imatinib levels (<1200 ng/mL) and low OCT-1 activity defined a group of patients who had the lowest rates of major molecular response (47%) by 24 months compared to all other patients (81%, P=0.009). These patients were also at the highest risk of failed imatinib therapy when compared to all other patients (P<0.001).

Conclusions

High-dose imatinib leads to superior molecular responses in patients with low OCT-1 activity. In this group trough imatinib levels may define a group with inferior outcomes. Among patients with high OCT-1 activity, neither higher imatinib dose nor monitoring imatinib trough levels was found to be of significant clinical value. Hence OCT-1 activity determined prior to the start of therapy in newly diagnosed CML patients provides a valuable prognostic tool to determine the optimal up-front dose of imatinib in patients with newly diagnosed chronic phase chronic myeloid leukemia.     

Early intervention during imatinib therapy in patients with newly diagnosed chronic-phase chronic myeloid leukemia: a study of the Spanish PETHEMA group

Background

Despite the favorable results of imatinib front line in chronic-phase chronic myeloid leukemia there is room for improvement.

Design and Methods

Early intervention during imatinib therapy was undertaken in 210 adults with chronic-phase chronic myeloid leukemia less than three months from diagnosis (Sokal high risk: 16%). Patients received imatinib 400 mg/day. At three months, dose was increased if complete hematologic response was not achieved. At six months, patients in complete cytogenetic response were kept on 400 mg and the remainder randomized to higher imatinib dose or 400 mg plus interferon-alfa. At 18 months, randomized patients were switched to a 2^nd generation tyrosine kinase inhibitor if not in complete cytogenetic response and imatinib dose increased in non-randomized patients not in major molecular response.

Results

Seventy-two percent of patients started imatinib within one month from diagnosis. Median follow-up is 50.5 (range: 1.2–78) months. At three months 4 patients did not have complete hematologic response; at six months 73.8% were in complete cytogenetic response; among the remainder, 9 could not be randomized (toxicity or consent withdrawal), 17 were assigned to high imatinib dose, and 15 to 400 mg + interferon-alpha. The low number of randomized patients precluded comparison between the two arms. Cumulative response at three years was: complete hematologic response 98.6%, complete cytogenetic response 90% and major molecular response 82%. On an intention-to-treat basis, complete cytogenetic response was 78.8% at 18 months. At five years, survival was 97.5%, survival free from accelerated/blastic phase 94.3%, failure free survival 82.5%, and event free survival (including permanent imatinib discontinuation) 71.5%.

Conclusions

These results indicate the benefit of early intervention during imatinib therapy (ClinicalTrials.gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT00390897","term_id":"NCT00390897"}}NCT00390897).     

Second-line salvage chemotherapy for transplant-eligible patients with Hodgkin's lymphoma resistant to platinum-containing first-line salvage chemotherapy

Background

The management of patients with relapsed or refractory Hodgkin’s lymphoma who achieve less than a partial response to first-line salvage chemotherapy is unclear. The objective of this study was to evaluate response and outcomes to second-line salvage and autologous stem cell transplantation in patients not achieving a complete or partial response to platinum-containing first-line salvage chemotherapy.

Design and Methods

Consecutively referred transplant-eligible patients with relapsed/refractory Hodgkin’s lymphoma after primary chemotherapy received gemcitabine, dexamethasone, and cisplatin as first salvage chemotherapy. Those achieving a complete or partial response, and those with a negative gallium scan and stable disease with bulk <5 cm proceeded to high-dose chemotherapy and autologous stem cell transplantation. Patients with progressive disease or stable disease with a positive gallium scan or bulk ≥5 cm were given second salvage chemotherapy with mini-BEAM (carmustine, etoposide, cytarabine, melphalan). Patients who responded (according to the same definition) proceeded to autologous stem cell transplantation.

Results

One hundred and thirty-one patients with relapsed/refractory Hodgkin’s lymphoma received first-line salvage gemcitabine, dexamethasone, and cisplatin; of these patients 99 had at least a partial response (overall response rate 76%). One hundred and twelve (85.5%) patients proceeded to autologous stem cell transplantation, while the remaining 19 (14.5%) patients received mini-BEAM. Among these 19 patients, six had at least a partial response (overall response rate 32%), and nine proceeded to autologous stem cell transplantation. The remaining ten patients received palliative care. Seven of the nine patients transplanted after mini-BEAM had a subsequent relapse. Patients receiving second salvage mini-BEAM had poor outcomes, with a 5-year progression-free survival rate of 11% and a 5-year overall survival rate of 20%.

Conclusions

Patients who require a second salvage regimen to achieve disease control prior to autologous stem cell transplantation have a relatively poor outcome and should be considered for alternative treatment strategies.     

Can anthocyanins improve maintenance therapy of Ph+ acute lymphoblastic leukaemia?

Chemotherapy and tyrosine kinase inhibitors provide high remission rates. However, prognosis of adult patients with Philadelphia chromosome–positive acute lymphoblastic leukaemia (Ph⁺ ALL) still remains poor. Because most adults eventually relapse without allogeneic stem cell transplantation, which is not available for all patients, novel strategies are required for relapse prevention. As the integrity of the immune system is essential for the control of remaining leukaemia cells, we compared the efficacy of anthocyanins, imatinib and a DNA‐based vaccine as non‐immunosuppressant components with 6‐mercaptopurine (6‐MP) to control minimal residual disease in vitro and in vivo using different leukaemia cell lines and syngeneic mice. Proliferation of Ph⁺ ALL was significantly better inhibited by anthocyanin‐rich berry extract or imatinib compared with 6‐MP. Although anthocyanins induced apoptosis in some leukaemia cell lines, the level of caspase‐3, caspase‐8 and caspase‐9 was significantly lower compared with imatinib and 6‐MP. When used as single components, anthocyanins and imatinib mesylate failed to eradicate pre‐existing Ph⁺ ALL in syngeneic mice, while 6‐MP led to 10% and DNA vaccination to 56% survival. Intriguingly, only the combination of DNA vaccination with berry extract but not with the isolated anthocyanin, cyanidin‐3‐rutinoside or imatinib further increased leukaemia‐free and overall survival, and 90% of lethally challenged mice survived. We suggest that induction and enhancement of a leukaemia‐specific immunity by DNA vaccination and anthocyanin‐rich berry extract can also decrease the relapse rate in patients with Ph⁺ ALL. Furthermore, this approach may serve as strategy for maintenance therapy of other malignancies.     

Impact of the use of autologous stem cell transplantation at first relapse both in naive and previously rituximab exposed follicular lymphoma patients treated in the GELA/GOELAMS FL2000 study

Background

We analyzed detailed characteristics and salvage treatment in 175 follicular lymphoma patients from the FL2000 study who were in progression after first-line therapy with or without addition of rituximab to chemotherapy and interferon.

Design and Methods

The impact of using autologous stem cell transplantation and/or rituximab administration at first progression was investigated, taking into account initial therapy. With a median follow up of 31 months, 3-year event free and overall survival rates after progression were 50% (95%CI 42–58%) and 72% (95%CI 64–78%), respectively.

Results

The 3-year event free rate of rituximab re-treated patients (n=112) was 52% (95%CI 41–62%) versus 40% (95%CI 24–55%) for those not receiving rituximab second line (n=53) (P=0.075). There was a significant difference in 3-year overall survival between patients receiving autologous stem cell transplantation and those not: 92% (95%CI 78–97%) versus 63% (95%CI 51–72%) (P=0.0003), respectively. In multivariate analysis, both autologous stem cell transplantation and period of progression/relapse affected event free and overall survival.

Conclusions

Regardless of front-line rituximab exposure, this study supports incorporating autologous stem cell transplantation in the therapeutic approach at first relapse for follicular lymphoma patients.     

Cytopenias after day 28 in allogeneic hematopoietic cell transplantation: impact of recipient/donor factors, transplant conditions and myelotoxic drugs

Background

Secondary cytopenias are serious complications following hematopoietic cell transplantation. Etiologies include myelotoxic agents, viral infections, and possibly transplant-related factors such as the intensity of the conditioning regimen and the source of stem cells.

Design and Methods

We retrospectively analyzed data from 2162 hematopoietic cell transplant recipients to examine the effect of these factors on overall cytopenias occurring after 28 days in hematopoietic cell transplantation.

Results

Advanced age of the patient, recipient cytomegalovirus seropositivity, unrelated donor status, human leukocyte antigen mismatch and lower doses of transplanted CD34⁺ cells (≤ 6.4×10⁶/kg) significantly increased the risk of cytopenias after day 28. Non-myeloablative hematopoietic cell transplantation had protective effects on anemia and thrombocytopenia after day 28 (adjusted odds ratio 0.76, probability value of 0.05 and adjusted odds ratio 0.31, probability value of <0.0001, respectively) but not on overall or ganciclovir-related neutropenia. This lack of protection appeared to be due to the use of mycophenolate mofetil in the majority of recipients of non-myeloablative hematopoietic cell transplants. Peripheral blood stem cells did not confer protection from cytopenias when compared to bone marrow.

Conclusions

Elderly patients appear to be more prone to cumulative toxicities of post-transplant drug regimens, but non-myeloablative conditioning, optimized human leukocyte antigen matching, and higher doses of CD34⁺ cell infusions may reduce the risk of cytopenia after day 28.     

Second-generation tyrosine kinase inhibitors improve the survival of patients with chronic myeloid leukemia in whom imatinib therapy has failed

Background

It has not been clearly established whether second-generation tyrosine kinase inhibitors actually improve the survival of patients with chronic myeloid leukemia in chronic phase who are given nilotinib or dasatinib therapy after treatment failure with imatinib.

Design and Methods

To address this issue we compared the survival of 104 patients in whom first-line therapy with imatinib failed and who were then treated with second-generation tyrosine kinase inhibitors with the outcome of 246 patients in whom interferon-α therapy failed and who did not receive tyrosine kinase inhibitor therapy.

Results

Patients treated with second-generation tyrosine kinase inhibitors had longer overall survival than the interferon controls (adjusted relative risk= 0.28, P=0.0001). However this survival advantage was limited to the 64.4% of patients in whom imatinib failed but who achieved complete cytogenetic response with the subsequent tyrosine kinase inhibitor (adjusted relative risk =0.05, P=0.003), whereas the 35.6% of patients who failed to achieve complete cytogenetic response on the second or third inhibitor had similar overall survival to that of the controls (adjusted relative risk=0.76, P=0.65).

Conclusions

Patients in whom imatinib treatment fails who receive sequential therapy with second-generation tyrosine kinase inhibitors have an enormous advantage in survival over controls (palliative therapy); this advantage is, however, limited to the majority of the patients who achieve a complete cytogenetic response.     

The long-term durability of cytogenetic responses in patients with accelerated phase chronic myeloid leukemia treated with imatinib 600 mg: the GIMEMA CML Working Party experience after a 7-year follow-up

Background

Imatinib mesylate is the first line treatment for chronic myeloid leukemia. The advent of imatinib increased survival significantly in patients in an advanced phase of the disease. However, few long-term data on the outcome of these patients based on large, prospective and controlled trials are available.

Design and Methods

A phase 2 multicenter trial of the use of imatinib 600 mg/daily in patients with accelerated phase chronic myeloid leukemia was sponsored and promoted by the Italian Cooperative Study Group on Chronic Myeloid Leukemia in 2001.

Results

One hundred and eleven patients were enrolled; the median follow-up of the 41 living patients is 82 months (range, 73–87). One hundred and seven patients (96%) returned to chronic phase and 79 patients (71%) achieved a complete hematologic response. Cumulative best rates of major cytogenetic response and complete cytogenetic response were 30% and 21%, respectively. All responses were maintained for a minimum of 4 weeks. At last follow-up, four patients were alive in complete remission after allogeneic transplant, 16 patients (14%) had switched to a second generation tyrosine kinase inhibitor and 21 patients (19%) were alive on imatinib therapy. No late toxicities were observed. Progression-free survival and event-free survival rates were 36.5% and 15%, respectively, at 7 years. The median survival time was 37 months, and was significantly associated with the achievement of a complete hematologic response or a complete cytogenetic response.

Conclusions

Imatinib may induce durable responses, associated with prolonged survival, in patients with accelerated phase chronic myeloid leukemia     

High rates of durable response are achieved with imatinib after treatment with interferon α plus cytarabine: results from the International Randomized Study of Interferon and STI571 (IRIS) trial

Background

Imatinib is the standard of care for newly diagnosed chronic-phase chronic myeloid leukemia. The largest randomized clinical trial of imatinib was the multinational IRIS trial in which 1106 patients were randomized to receive either imatinib 400 mg/day or a standard regimen of interferon-α plus cytarabine.

Design and Methods

Patients were allowed to cross over to the opposite treatment for intolerance, lack of response, disease progression, and, following release of the initial efficacy data, reluctance to remain on therapy with interferon-α plus cytarabine. The safety and efficacy of imatinib in patients who crossed over from interferon-α plus cytarabine to imatinib is reported here.

Results

Of 553 patients originally assigned to interferon-α plus cytarabine, 65% crossed over to imatinib, of whom 67% continue to receive treatment. After a median of 54 months of imatinib treatment on study, 93% achieved complete hematologic remission, 86% achieved major cytogenetic remission, and 81% achieved a complete cytogenetic remission as the best observed response. Estimated rates of freedom from progression to accelerated or blast phase and overall survival were 91% and 89%, respectively, at 48 months after starting imatinib.

Conclusions

This is the largest analysis to date describing the efficacy of imatinib in patients who have received prior therapies for chronic myeloid leukemia and it demonstrates excellent responses to this treatment. (ClinicalTrials.gov identifier: {"type":"clinical-trial","attrs":{"text":"NCT00006343","term_id":"NCT00006343"}}NCT00006343)     

Value of allogeneic versus autologous stem cell transplantation and chemotherapy in patients with myelodysplastic syndromes and secondary acute myeloid leukemia. Final results of a prospective randomized European Intergroup Trial

Background

Allogeneic stem cell transplantation is usually considered the only curative treatment option for patients with advanced or transformed myelodysplastic syndromes in complete remission, but post-remission chemotherapy and autologous stem cell transplantation are potential alternatives, especially in patients over 45 years old.

Design and Methods

We evaluated, after intensive anti-leukemic remission-induction chemotherapy, the impact of the availability of an HLA-identical sibling donor on an intention-to treat basis. Additionally, all patients without a sibling donor in complete remission after the first consolidation course were randomized to either autologous peripheral blood stem cell transplantation or a second consolidation course consisting of high-dose cytarabine.

Results

The 4-year survival of the 341 evaluable patients was 28%. After achieving complete remission, the 4-year survival rates of patients under 55 years old with or without a donor were 54% and 41%, respectively, with an adjusted hazard ratio of 0.81 (95% confidence interval [95% CI], 0.49–1.35) for survival and of 0.67 (95% CI, 0.42–1.06) for disease-free survival. In patients with intermediate/high risk cytogenetic abnormalities the hazard ratio in multivariate analysis was 0.58 (99% CI, 0.22–1.50) (P=0.14) for survival and 0.46 (99% CI, 0.22–1.50) for disease-free survival (P=0.03). In contrast, in patients with low risk cytogenetic characteristics the hazard ratio for survival was 1.17 (99% CI, 0.40–3.42) and that for disease-free survival was 1.02 (99% CI, 0.40–2.56). The 4-year survival of the 65 patients randomized to autologous peripheral blood stem cell transplantation or a second consolidation course of high-dose cytarabine was 37% and 27%, respectively. The hazard ratio in multivariate analysis was 1.22 (95% CI, 0.65–2.27) for survival and 1.02 (95% CI, 0.56–1.85) for disease-free survival.

Conclusions

Patients with a donor and candidates for allogeneic stem cell transplantation in first complete remission may have a better disease-free survival than those without a donor in case of myelodysplastic syndromes with intermediate/high-risk cytogenetics. Autologous peripheral blood stem cell transplantation does not provide longer survival than intensive chemotherapy. (Eudract number: NCT00002926; http://www.cancer.gov/clinicaltrials/EORTC-06961)     

Bone marrow mesenchymal stromal cells non-selectively protect chronic myeloid leukemia cells from imatinib-induced apoptosis via the CXCR4/CXCL12 axis

Background

Residual chronic myeloid leukemia disease following imatinib treatment has been attributed to the presence of quiescent leukemic stem cells intrinsically resistant to imatinib. Mesenchymal stromal cells in the bone marrow may favor the persistence and progression of leukemia by preserving the proliferation and self-renewal capacities of the malignant progenitor cells.

Design and Methods

BV173 or primary chronic myeloid leukemia cells were co-cultured with human mesenchymal stromal cells and imatinib-induced cell death was then measured. The roles of pro-and anti-apoptotic proteins and chemokine CXCL12 in this context were evaluated. We also studied the ability of BV173 cells to repopulate NOD/SCID mice following in vitro exposure to imatinib and mesenchymal stromal cells.

Results

Whilst imatinib induced dose-dependent apoptosis of BV173 cells and primary chronic myeloid leukemia cells, co-culture with mesenchymal stromal cells protected both types of chronic myeloid leukemia cells. Molecular analysis indicated that mesenchymal stromal cells reduced caspase-3 activation and modulated the expression of the anti-apoptotic protein Bcl-XL. Furthermore, chronic myeloid leukemia cells exposed to imatinib in the presence of mesenchymal stromal cells retained the ability to engraft into NOD/SCID mice. We observed that chronic myeloid leukemia cells and mesenchymal stromal cells express functional levels of CXCR4 and CXCL12, respectively. Finally, the CXCR4 antagonist, AMD3100 restored apoptosis by imatinib and the susceptibility of the SCID leukemia repopulating cells to the tyrosine kinase inhibitor.

Conclusions

Human mesenchymal stromal cells mediate protection of chronic myeloid leukemia cells from imatinib-induced apoptosis. Disruption of the CXCL12/CXCR4 axis restores, at least in part, the leukemic cells’ sensitivity to imatinib. The combination of anti-CXCR4 antagonists with tyrosine kinase inhibitors may represent a powerful approach to the treatment of chronic myeloid leukemia.     

Dose-dense and high-dose chemotherapy plus rituximab with autologous stem cell transplantation for primary treatment of diffuse large B-cell lymphoma with a poor prognosis: a phase II multicenter study

Background

We investigated the addition of rituximab to dose-dense and high-dose chemotherapy with autologous stem cell transplantation in patients with untreated poor-prognosis diffuse large B-cell lymphoma.

Design and Methods

Ninety-four young patients (age, 18–60) with stage III–IV diffuse large B-cell lymphoma at intermediate/high or high risk according to the age-adjusted International Prognostic Index were enrolled into a phase II trial. The treatment was as follows: four courses of bi-weekly rituximab-cyclophosphamide-epirubicin-vincristine-prednisone (R-MegaCEOP14), two courses of rituximab-mitoxantrone-cytarabine-dexamethasone (R-MAD) and carmustine-etoposide-cytarabine-melphalan (BEAM) with autologous stem cell transplantation.

Results

The complete response and toxic death rates were 82% and 5%, respectively. Failure-free survival and overall survival rates at 4 years were 73% and 80%, respectively. The outcomes of these patients were retrospectively compared to those of 41 patients with similar characteristics enrolled into a previous phase II trial of high-dose chemotherapy without rituximab. This historical group was treated with eight weekly infusions of methotrexate-doxorubicin-cyclophosphamide-vincristine-prednisone-bleomycin (MACOP-B), two courses of MAD and BEAM with autologous stem cell transplantation. The 4-year failure-free survival rates for the rituximab and historical groups were 73% versus 44%, respectively (p=0.001); the 4-year overall survival rates were 80% and 54%, respectively (p=0.002). A Cox’s multivariable model was applied to adjust the effect of treatment for unbalanced or important prognostic factors: failure and death risks were significantly reduced in the rituximab group compared to the historical group, with an adjusted hazard ratio of 0.44 (p=0.01) for failure-free survival and 0.46 (p=0.02) for overall survival.

Conclusions

These results suggest that the addition of rituximab to high-dose chemotherapy is effective and safe in diffuse large B-cell lymphoma with a poor-prognosis and such regimens need to be compared to dose-dense chemoimmunotherapy without autologous stem cell transplantation in randomized trials.     

Intermediate dose of imatinib in combination with chemotherapy followed by allogeneic stem cell transplantation improves early outcome in paediatric Philadelphia chromosome-positive acute lymphoblastic leukaemia (ALL): results of the Spanish Cooperative Group SHOP studies ALL-94, ALL-99 and ALL-2005

Philadelphia‐chromosome acute lymphoblastic leukaemia (Ph+ ALL) is a subgroup of ALL with very high risk of treatment failure. We report here the results of the Sociedad Española de Hematología y Oncología Pediátricas (SEHOP/SHOP) in paediatric Ph+ ALL treated with intermediate‐dose imatinib concurrent with intensive chemotherapy. The toxicities and outcome of these patients were compared with historical controls not receiving imatinib. Patients with Ph+ ALL aged 1–18 years were enrolled in three consecutive ALL/SHOP trials (SHOP‐94/SHOP‐99/SHOP‐2005). In the SHOP‐2005 trial, imatinib (260 mg/m² per day) was given on day‐15 of induction. Allogeneic haematopoietic stem‐cell transplantation (HSCT) from a matched related or unrelated donor was scheduled in first complete remission (CR1). Forty‐three patients were evaluable (22 boys, median age 6·8 years, range, 1·2–15). Sixteen received imatinib whereas 27 received similar chemotherapy without imatinib. Seventeen of 27 and 15 of 16 patients in the non‐imatinib and imatinib cohort, respectively, underwent HSCT in CR1. With a median follow‐up of 109 and 39 months for the non‐imatinib and imatinib cohorts, the 3‐year event‐free survival (EFS) was 29·6% and 78·7%, respectively (P = 0·01). These results show that, compared to historical controls, intermediate dose of imatinib given concomitantly with chemotherapy and followed by allogeneic HSCT markedly improved early EFS in paediatric Ph+ ALL.     

Efficacy of escalated imatinib combined with cytarabine in newly diagnosed patients with chronic myeloid leukemia

Background

In order to improve the molecular response rate and prevent resistance to treatment, combination therapy with different dosages of imatinib and cytarabine was studied in newly diagnosed patients with chronic myeloid leukemia in the HOVON-51 study.

Design and Methods

Having reported feasibility previously, we hereby report the efficacy of escalated imatinib (200 mg, 400 mg, 600 mg or 800 mg) in combination with two cycles of intravenous cytarabine (200 mg/m² or 1000 mg/m² days 1 to 7) in 162 patients with chronic myeloid leukemia.

Results

With a median follow-up of 55 months, the 5-year cumulative incidences of complete cytogenetic response, major molecular response, and complete molecular response were 89%, 71%, and 53%, respectively. A higher Sokal risk score was inversely associated with complete cytogenetic response (hazard ratio of 0.63; 95% confidence interval, 0.50–0.79, P<0.001). A higher dose of imatinib and a higher dose of cytarabine were associated with increased complete molecular response with hazard ratios of 1.60 (95% confidence interval, 0.96–2.68, P=0.07) and 1.66 (95% confidence interval, 1.02–2.72, P=0.04), respectively. Progression-free survival and overall survival rates at 5 years were 92% and 96%, respectively. Achieving a major molecular response at 1 year was associated with complete absence of progression and a probability of achieving a complete molecular response of 89%.

Conclusions

The addition of intravenous cytarabine to imatinib as upfront therapy for patients with chronic myeloid leukemia is associated with a high rate of complete molecular responses (Clinicaltrials.Gov Identifier: {"type":"clinical-trial","attrs":{"text":"NCT00028847","term_id":"NCT00028847"}}NCT00028847).     

OCT-1 function varies with cell lineage but is not influenced by BCR-ABL

Background

Despite the excellent responses to imatinib therapy observed in patients with chronic phase chronic myeloid leukemia, approximately 25% of patients display primary resistance or suboptimal response. The OCT-1 activity in mononuclear cells reflects the efficiency of active influx of imatinib. OCT-1 activity in mononuclear cells is highly variable between patients and significantly correlates with a patient’s molecular response to imatinib treatment and overall survival. The present study examined whether cell lineage and BCR-ABL expression influenced OCT-1 activity.

Design and Methods

The OCT-1 activity and OCT-1 mRNA expression was assessed in pure populations of neutrophils, monocytes and lymphocytes recovered from chronic myeloid leukemia patients at diagnosis, in cytogenetic remission and normal individuals. The role of BCR-ABL on OCT-1 activity and differentiation was examined in a cell line model of ectopic BCR-ABL expression.

Results

The OCT-1 activity and OCT-1 mRNA expression was highest in the neutrophil population and lowest in lymphocytes (P<0.05). This was observed for patients at diagnosis, in cytogenetic remission and normal individuals. Interestingly, neutrophil OCT-1 activity was not significantly different between patients at diagnosis, in remission and normal donors. This was also observed for monocytes and lymphocytes. Furthermore, OCT-1 activity in mononuclear cells was significantly correlated with the OCT-1 activity in neutrophils (P=0.001). In a cell line model in which BCR-ABL was ectopically expressed, we found no evidence that BCR-ABL directly affected OCT-1 expression and function. However, BCR-ABL stimulated granulocyte differentiation which, in turn, led to significantly increased OCT-1 activity (P=0.024).

Conclusions

These studies suggest that the predictive OCT-1 activity in patient mononuclear cells is strongly related to cell lineage, particularly the presence of neutrophils in the peripheral blood. Furthermore, BCR-ABL expression is unlikely to directly influence OCT-1 activity but may have an indirect role by enhancing granulocyte differentiation.