Fabian Zohren

The monoclonal anti-VLA-4 antibody natalizumab mobilizes CD34 hematopoietic progenitor cells in humans

We investigated the role of adhesion molecule VLA-4 in CD34+ blood stem-cell mobilization. Therefore, we examined 20 patients with multiple sclerosis (MS) who were treated with the anti-VLA-4 antibody natalizumab. Treated patients had received a median number of 4 natalizumab infusions (range: 2-9 infusions). Blood samples were taken 4 weeks following the last infusion. With a median proportion of 7.6 CD34+ cells/microL (range: 2.2-30.4 cells/microL), these patients had a significantly higher (P=.003) amount of circulating CD34+ cells compared with 5 healthy volunteers (median: 1.4/microL; range: 0.6-2.4/microL) and 5 untreated MS patients (median: 1.0/microL; range: 0.5-1.7/microL) (P=.001). Serial measurements in 4 patients receiving their first natalizumab infusion showed a maximal significant increase in circulating CD34+ cells from 3.3/microL (range: 1.6-4.8/microL) to 10.4/microL (range: 7.5-12.04/microL) 72 hours following natalizumab infusion (P=.001), including pluripotent cells in colony-forming assays. This mobilizing ability of natalizumab might be useful for patients with poor response to granulocyte colony-stimulating factor (G-CSF)-based protocols.

Escalation therapy with bortezomib, dexamethasone and bendamustine for patients with relapsed or refractory multiple myeloma

In order to improve remission rates without causing undue toxicity, we treated 50 patients with relapsed/refractory multiple myeloma according to an institutional sequential treatment algorithm. Bortezomib was given as monotherapy (1.3 mg/m2 on day 1 + 4 + 8 + 11) followed by the addition of dexamethasone in a first (40 mg on day 1 + 4 + 8 + 11) and bendamustine (50 – 100 mg/m2 on day 1 + 8) in a second escalation step for patients with less than a minor response. Bortezomib monotherapy was sufficient in 23 (46%) patients, treatment escalation with dexamethasone was necessary in 20 (40%) patients and 7 (14%) patients needed triple combination therapy. Overall response rate was 84% while toxicity was manageable. Median time to progression and overall survival were 8 and 20 months, respectively. In conclusion, this treatment algorithm resulted in responses in the majority of heavily pre-treated patients while at the same time restricting the toxicity of triple combination therapy to only 14% of non-responding patients.

CD34+ progenitor cells mobilized by natalizumab are not a relevant reservoir for JC virus

Background: Progressive multifocal leukoencephalopathy (PML) is associated with natalizumab treatment in patients with multiple sclerosis (MS). It has been hypothesized that natalizumab mobilizes JC virus (JCV)-infected haematopoietic progenitor cells mediating viraemia and subsequently this disease. Objective: The objective of this study was to investigate peripheral haematopoietic progenitor cells for evidence of JCV DNA in MS patients treated with natalizumab. Methods: We assessed JCV and cytomegalovirus (CMV) DNA in magnetically separated CD34+ haematopoietic progenitor cells, peripheral blood mononuclear cells and plasma of 67 natalizumab-treated patients with MS and six PML patients. Results: Viral DNA was not detectable in CD34+ haematopoietic progenitor or peripheral blood mononuclear cells from any sample. Two plasma samples from patients with MS while undergoing natalizumab treatment were JCV-positive. In one case clinically manifest PML developed 8 months thereafter. Conclusions: Our findings do not support the hypothesis that natalizumab mobilizes JC virus-infected CD34+ cells from the bone marrow mediating JC viraemia. Notably, JC viraemia was detected in one patient with MS prior to developing clinical PML. This warrants further study.

Reliable engraftment, low toxicity, and durable remissions following allogeneic blood stem cell transplantation with minimal conditioning

OBJECTIVE Allogeneic blood stem cell transplantation (BSCT) can cure patients with hematologic malignancies by high-dose chemotherapy and allogeneic graft-vs-tumor (GvT) reactions. To avoid high-dose conditioning and evaluate engraftment, toxicity, and GvT reactions, we treated a group of high-risk patients with a minimal intensive conditioning regimen followed by allogeneic BSCT. MATERIALS AND METHODS Thirty-four patients with lymphoma (11), myeloma (10), chronic myeloid leukemia (4), myelodysplastic syndrome (5), and acute myeloid leukemia (4) were treated with fludarabine (3 x 30 mg/m(2)) and 200 cGy total-body irradiation followed by the infusion of peripheral blood stem cells from related (28) or unrelated (6) donors. Cyclosporine or tacrolimus and mycophenolate mofetile were given posttransplant. Most patients had advanced disease, were intensively pretreated, and had contraindications against conventional myeloablative transplantation. RESULTS Thirty-two patients (94%) had engraftment of donor cells. Patients with lymphatic malignancies developed complete donor chimerism significantly faster than patients with myeloid malignancies (p < 0.05). Clinical responses were observed in 16 of 27 patients (59%) who had active disease at transplantation. Of 7 patients who were treated in remission, 5 remain free of disease. After a median follow-up of 325 days (range 100-844) 22 patients are alive (65%, 14 CR, 4 PR, 4 PD). Two patients (6%) died of treatment-related complications and 10 patients (29%) died of progressive disease. Acute graft-vs-host-disease (GvHD) of grade II or more developed in 17 patients (50%). Chronic GvHD is present in 10 of 22 patients (45%) who are alive beyond day 100. CONCLUSIONS Toxicity and survival in this group of high-risk patients are superior to those expected with conventional allogeneic transplantation. GvT reactions frequently occur in conjunction with GvHD and can induce durable remissions in patients with advanced hematologic malignancies.

Therapy-related myeloid neoplasms following treatment with radioiodine

Background Few data are available on therapy-related myelodysplastic syndromes and acute myeloid leukemia developing after radioiodine treatment. Design and Methods We retrospectively analyzed 39 patients with myeloid neoplasms following radioiodine treatment, whose data were reported to the Duesseldorf Myelodysplastic Syndromes Register (8 of 3814 patients) and five other German Myelodysplastic Syndromes centers (n=31) between 1982 and 2011. These data were compared with those from 165 patients from our Myelodysplastic Syndromes Register with therapy-related myeloid neoplasms following chemotherapy (n=90), radiation (n=30), or radiochemotherapy (n=45). Results With a median latency of 79 months, 18 patients developed therapy-related acute myeloid leukemia and 21 presented with therapy-related myelodysplastic syndromes (8 refractory anemia with excess blasts I/II, 6 refractory anemia with multilineage dysplasia, 3 myelodysplastic syndromes with del(5q), 1 refractory anemia, 1 refractory anemia with ring sideroblasts, 1 chronic myelomonocytic leukemia II, 1 myelodysplastic/myeloproliferative neoplasm unclassifiable). Risk assessment according to the International Prognostic Scoring System was low-risk in 23%, intermediate-1 in 29%, intermediate-2 in 35%, and high-risk in 13%. Karyotype was abnormal in 68%, with chromosomes 7 (30%), 5 (26%), 8 (26%) and 3 (17%) being most frequently affected. No differences in the distribution of gender, World Health Organization subtype, acute myeloid leukemia progression, International Prognostic Scoring System score, and cytogenetic risk were observed between patients with therapy-related myeloid neoplasms following radioiodine or other treatment modalities. Of 17 patients who received induction chemotherapy, 71% were refractory to this treatment or died from treatment-related toxicity. The median overall survival in the entire group was 21.7 months (95%-CI 10.5–33 months) and did not differ significantly in comparison to the survival of patients with therapy-related myeloid neoplasms following other cytotoxic treatments. Patients with therapy-related acute myeloid leukemia had significantly inferior overall survival (12.4 versus 28.7 months, P=0.002). Conclusions Patients developing a therapy-related myeloid neoplasm after radioiodine treatment usually present with biological characteristics similar to those seen in patients with therapy-related myeloid neoplasms following other cytotoxic treatment modalities, associated with a low response rate to induction chemotherapy and poor prognosis.

Natalizumab and Impedance of the Homing of CD34+ Hematopoietic Progenitors

BACKGROUND Treatment with natalizumab, an antibody blocking the α4-integrin, is associated with increased numbers of circulating CD34+ cells in the peripheral blood of patients with multiple sclerosis. OBJECTIVE To determine whether natalizumab mobilizes CD34+ cells from or inhibits homing to the bone marrow (BM). DESIGN Fifty-two patients with relapsing-remitting multiple sclerosis treated with natalizumab were included. Flow cytometric analyses; polymerase chain reaction assays for JC (John Cunningham) virus DNA detection; and adhesion, migration, and apoptosis assays of immunomagnetically enriched peripheral blood and BM CD34+ cells were conducted. A comparison was made with CD34+ cells from granulocyte colony-stimulating factor-mobilized peripheral blood or steady-state BM of age- and sex-matched healthy donors. RESULTS We found adhesion and migration of peripheral blood-derived CD34+ cells to be reduced. In BM aspirates from natalizumab-treated patients, the cellularity, the proportion, and the adhesive capacity of CD34+ cells were normal. The JC virus was undetectable. CONCLUSIONS Natalizumab mediates an increase in circulating CD34+ cells by interfering with homing to the BM. Thus, CD34+ cells appear unlikely to represent a source mobilizing JC virus out of the BM in patients treated with natalizumab.

The role of natalizumab in hematopoietic stem cell mobilization.

The humanized monoclonal very late antigen 4 (VLA-4) antibody natalizumab is FDA approved for the treatment of patients with multiple sclerosis and Crohns disease. In this review we focus on its role in the context of hemato-poietic stem cell transplantation and stem cell diseases. The use of natalizumab alone or in combination with either cytotoxic drugs or other antibodies might be a new modality for stem cell mobilization and a therapeutic option for patients with hematologic malignancies.

Upfront Allogeneic Blood Stem Cell Transplantation for Patients with High-Risk Myelodysplastic Syndrome or Secondary Acute Myeloid Leukemia Using a FLAMSA-Based High-Dose Sequential Conditioning Regimen

Patients suffering from high-risk myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML) secondary to MDS (sAML) are characterized by poor response to conventional cytotoxic chemotherapy. The purpose of our prospective single-center study was to examine the safety and efficacy of an allogeneic hematopoietic stem cell transplantation (HSCT) following a sequential conditioning regimen as first-line therapy for previously untreated patients with high-risk MDS or sAML. Between November 2003 and June 2010, 30 patients (20 high-risk MDS, 10 sAML) received fludarabine (4 × 30 mg/m(2)), amsacrine (4 × 100 mg/m(2)), and Ara-C (4 × 2 g/m(2), FLAMSA). After 2 to 3 days of rest, patients received high-dose melphalan alone (200 mg/m(2) for patients with an age <50 years, 150 mg/m(2) for patients with an age between 50 and 60 years, and 100 mg/m(2) for patients with an age >60 years; n = 24) or melphalan and thiotepa (10 mg/kg, Mel/Thio, n = 6). Following these high-dose conditioning regimens, a median number of 7.7 × 10(6) CD34(+) cells/kg body weight (range: 2.9 × 10(6)-17.2 × 10(6)) were transplanted from 13 related or 17 unrelated donors. Antithymocyte globulin (Fresenius 30-60 mg/kg) as well as tacrolimus and mycophenolate mofetil were used for graft-versus-host disease (GVHD) prophylaxis. All patients except 1 with primary graft failure achieved complete remission after HSCT. After a median follow-up time of 28 months (range: 7-81), 21 patients (70%) were alive and free of disease. Overall, 4 patients relapsed. At 2 years, overall survival, event-free survival, and treatment-related mortality were 70%, 63%, and 30%, respectively. Because of undue toxicity, thiotepa is no longer part of the conditioning regimen. Our results add to the body of evidence that a FLAMSA-based sequential conditioning therapy is effective for previously untreated patients with high-risk MDS or sAML.

Sorafenib treatment in 13 patients with acute myeloid leukemia and activating FLT3 mutations in combination with chemotherapy or as monotherapy.

Following the demonstration of its anti-leukemic properties in vitro and in FLT3-positive mouse models, we and other groups have shown the therapeutic efficacy of sorafenib monotherapy in a group comprising a total of 26 patients with FLT3+ AML, with some of them achieving even a complete molecular response [4–9] . Recently, Ravandi et al. [10] have published results from a phase I/II trial, in which 61 patients with either relapsed/refractory (n = 10) or de novo AML (n = 51) were treated with sorafenib together with a classical induction chemotherapy consisting of idarubicin and cytarabine without increased toxicity. In this study, 22 of 61 patients carried a FLT3 mutation and these patients had a significantly higher complete remission (CR) rate compared to the patients with wild-type (WT) FLT3. Here, we present the results of 13 patients with AML carrying activating FLT3 mutations who were treated with sorafenib as an individual treatment decision at our hospital and were therefore included into this retrospecMutations in the gene encoding the Fms-like tyrosine-3 kinase (FLT3) are present in 25–40% of the patients with de novo acute myeloid leukemia (AML) and lead to a constitutive activation of this receptor kinase thereby increasing the proliferation of AML blasts [1] . While the prognostic significance of the less frequent point mutation (D835) in the tyrosine kinase domain (TKD) of FLT3 is not yet clear, internal tandem duplication (ITD) mutations within the juxtamembrane domain are more frequent and go along with a higher relapse rate and a worse overall survival. Several FLT3 inhibitors such as lestaurtinib, midostaurin and tandutinib have shown clinical activity in patients with FLT3-positive AML and act synergistically with standard cytotoxic agents. In order to improve the outcome of these patients, these small molecules are under ongoing investigations [2, 3] . Sorafenib is a multikinase inhibitor approved for the treatment of metastatic hepatocellular and renal cell carcinoma. Besides its inhibitory activity on Raf, the vascular endothelial growth factor receptor and the plateletderived growth factor receptor, sorafenib also targets the FLT3 receptor tyrosine kinase. Received: May 25, 2010 Accepted after revision: July 31, 2010 Published online: October 11, 2010

Prognostic value of circulating Bcl-2/IgH levels in patients with follicular lymphoma receiving first-line immunochemotherapy.

Bcl-2/IgH rearrangements can be quantified in follicular lymphoma (FL) from peripheral blood (PB) by polymerase chain reaction (PCR). The prognostic value of Bcl-2/IgH levels in FL remains controversial. We therefore prospectively studied PB Bcl-2/IgH levels from 173 first-line FL patients who were consecutively enrolled, randomized, and treated within the multicenter phase 3 clinical trial NHL1-2003 comparing bendamustine-rituximab (B-R) with rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone. From April 2005 to August 2008, 783 pre- and posttreatment PB samples were quantified by quantitative PCR. At inclusion, 114 patients (66%) tested positive and 59 (34%) were negative for Bcl-2/IgH. High pretreatment Bcl-2/IgH levels had an adverse effect on progression-free survival (PFS) compared with intermediate or low levels (high vs intermediate: hazard [HR], 4.28; 95% confidence interval [CI], 1.70-10.77; P = .002; high vs low: HR, 3.02; 95% CI, 1.55-5.86; P = .001). No PFS difference between treatment arms was observed in Bcl-2/IgH-positive patients. A positive posttreatment Bcl-2/IgH status was associated with shorter PFS (8.7 months vs not reached; HR, 3.15; 95% CI, 1.51-6.58; P = .002). By multivariate analysis, the pretreatment Bcl-2/IgH level was the strongest predictor for PFS. Our data suggest that pre- and posttreatment Bcl-2/IgH levels from PB have significant prognostic value for PFS in FL patients receiving first-line immunochemotherapy. This trial was registered at www.clinicaltrials.gov as #NCT00991211 and at the German Federal Institute for Drugs and Medical Devices as #BfArM-4021335.