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HLA-haploidentical haematopoietic stem cell transplantation (haplo-HSCT) is increasingly offered to patients with high-risk acute leukaemia. Unfortunately, haplo-HSCT is followed by a delayed immunoreconstitution. The aim of this EBMT registry study was to explore the clinical impact of lymphocyte subset counts after haplo-HSCT. We considered 144 leukaemic patients transplanted in the period 2001-2012. Pre-transplantation clinical variables and differential immune-cell counts (CD3, CD4, CD8 T cells, NK and B cells) measured before day 100 were evaluated for their capacity to predict overall survival, relapse mortality or non-relapse mortality (NRM). Negative prognostic factors for overall survival were advanced disease state at transplantation, host age and CMV seropositivity. Higher CD3, CD4 and CD8 counts were associated with a better overall survival and a lower NRM. Strikingly, when tested in multivariable analysis, higher CD3 and CD8 counts were still significantly associated with a lower NRM. These results indicate that an accelerated T-cell reconstitution correlates with less transplantation mortality, likely due to the protective role of T cells against viral infections. This observation suggests that CD8+ T-cell counts should be investigated as surrogate biomarkers of outcome in prospective haplo-HSCT trials.

In Press., In the absence of an HLA-matched donor, the best treatment for acquired aplastic anemia patients refractory to immunosuppression is unclear. We collected and analyzed data from all acquired aplastic anemia patients who underwent a haploidentical transplantation with posttransplant cyclophosphamide in Europe from 2011 to 2017 (n = 33). The cumulative incidence of neutrophil engraftment was 67% (CI95%: 51–83%) at D +28 and was unaffected by age group, stem cell source, ATG use, or Baltimore conditioning regimen. The cumulative incidence of grades II–III acute GvHD was 23% at D +100, and limited chronic GvHD was 10% (0–20) at 2 years, without cases of grade IV acute or extensive chronic GvHD. Two-year overall survival was 78% (64–93), and 2-year graft-versus-host disease-free survival was 63% (46–81). In univariate analysis, the 2-year OS was higher among patients who received the Baltimore conditioning regimen (93% (81–100) versus 64% (41–87), p = 0.03), whereas age group, stem cell source, and ATG use had no effect. Our results using unmanipulated haploidentical transplantation and posttransplant cyclophosphamide for treating refractory AA patients are encouraging, but warrant confirmation in a prospective study with a larger number of patients and longer follow-up.

Background. BK virus-associated hemorrhagic cystitis (BKV-HC) is a severe complication after allogeneic hematopoietic stem cell transplantation (HSCT), but antiviral treatment for this condition has not been evaluated. Methods. We conducted a retrospective survey on the safety and outcome of cidofovir treatment for patients with BKV-HC in centers affiliated with the European Group for Blood and Marrow Transplantation. Results. From 1 April 2004 to 31 December 2007, 62 patients received a diagnosis of BKV-HC after a median interval of 35 days after HSCT (range, 3-577 days). Fifty-seven patients (92%) received intravenous cidofovir, whereas 5 patients received cidofovir intravesically. Complete response (CR) was recorded in 38 (67%) of 57 patients with HC treated with intravenous cidofovir, whereas partial response (PR) was documented in 7 patients (12%). CR was documented in 3 patients and PR in 1 patient with HC treated with intravesical cidofovir. A reduction of 1-3 logs in BKV load was documented in 8 of the 10 patients achieving CR. Mild-to-moderate toxic effects were recorded in 18 of 57 patients who received intravenous cidofovir administration. In a multivariate analysis, the factors significantly associated with response to cidofovir were the stem cell source (Pp. 01) and the use of total body irradiation (P = .03). After a median follow-up of 287 days, overall survival and total treatment-related mortality rates were 63% and 40% for patients achieving CR, compared with 14% and 72% for patients with PR or no response to cidofovir, respectively (P < .001 and P = .001, respectively). Conclusions. Cidofovir may be a potentially effective therapy for BKV-HC, but evidence supporting its use requires randomized controlled trials.

Background The use of haploidentical hematopoietic cell transplantation (haplo-HCT) with posttransplantation cyclophosphamide prophylaxis is gaining traction in patients with acute lymphoblastic leukemia (ALL). Methods The Acute Leukemia Working Party/European Society for Blood and Marrow Transplantation registry was used to evaluate the outcomes of adult patients with ALL who underwent haplo-HCT during 2011 through 2015 and compared them with the outcomes of those who underwent transplantation during 2016 through 2018. Results The analysis consisted of 195 patients, including 79 who underwent transplantation during 2011 through 2015 and 116 who underwent transplantation during 2016 through 2018. Overall, the 2-year leukemia-free survival and relapse incidence rates were 56.5% and 21%, respectively. The 100-day incidence of grade 2 through 4 acute graft-vs-host disease (GVHD) was 34.5%. The rates of nonrelapse mortality (NRM) and overall survival (OS) were 22.5% and 64.7%, respectively. Patients who underwent transplantation during 2016 through 2018 experienced improved rates of leukemia-free survival (64.9% vs 47.3%; P = .019) and OS (75.5% vs 53.5%; P = .006). Patients who underwent transplantation during 2016 through 2018 developed more grade 2 through 4 acute GVHD (42% vs 26.4%; P = .047). The incidence of relapse, GVHD-free/relapse-free survival, grade 3 and 4 acute GVHD, chronic GVHD, and extensive chronic GVHD did not differ significantly between groups. In multivariate analysis, more recently transplanted patients had a significantly reduced risk of NRM (hazard ratio, 0.44; 95% CI, 0.22-0.89; P = .022) and improved OS (hazard ratio, 0.47; 95% CI, 0.26-0.86; P = .014). A comparable analysis of patients who had acute myeloid leukemia during the same timeframes did not reveal any statistically significant differences in any outcomes. Conclusions The outcome of adult patients with ALL who receive posttransplant cyclophosphamide has improved over time, with an impressive 2-year OS of 75% and, most recently, an NRM rate of only 17%.

Allogeneic hematopoietic cell transplantation (HCT) is recommended in high-risk patients with T cell acute lymphoblastic leukemia (T-ALL). For patients without an HLA-identical donor, haploidentical (haplo-) HCT is becoming the leading source of stem cell donation. However, data are scarce on predictive factors for outcome in that setting. We identified 122 adults (20% female; median age, 31 years; range, 18 to 68 years) with T-ALL who underwent haplo-HCT with post-transplantation cyclophosphamide (ptCy) between 2010 and 2017. The median duration of follow-up of living patients was 23 months. The 2-year incidences of relapse and nonrelapse mortality were 45% and 21%, respectively. The 2-year leukemia-free survival (LFS), overall survival (OS), and graft-versus-host disease, relapse-free survival (GRFS) were 34%, 42%, and 27%, respectively. The 2-year LFS and OS were highly influenced by disease status at transplantation, being 49% and 55%, respectively, for patients in first complete remission (CR1); 34% and 50%, respectively, for those in second CR (CR2); and 8% and 12%, respectively, for patients with active disease. On multivariate analysis, only disease status was found to affect LFS and OS. Transplantation in CR2 negatively affected LFS, whereas active disease at the time of haplo-HCT negatively affected LFS and OS. In conclusion, haplo-HCT with ptCy produced encouraging results in this challenging disease, particularly when performed in patients in CR. Despite the limitation of the small sample size, our results were not affected by the type of conditioning, calling into question the need for total body irradiation-based myeloablative conditioning in that setting.

Purpose Deficiency of adenosine deaminase 2 (DADA2) is an inherited inborn error of immunity, characterized by autoinflammation (recurrent fever), vasculopathy (livedo racemosa, polyarteritis nodosa, lacunar ischemic strokes, and intracranial hemorrhages), immunodeficiency, lymphoproliferation, immune cytopenias, and bone marrow failure (BMF). Tumor necrosis factor (TNF-α) blockade is the treatment of choice for the vasculopathy, but often fails to reverse refractory cytopenia. We aimed to study the outcome of hematopoietic cell transplantation (HCT) in patients with DADA2. Methods We conducted a retrospective study on the outcome of HCT in patients with DADA2. The primary outcome was overall survival (OS). Results Thirty DADA2 patients from 12 countries received a total of 38 HCTs. The indications for HCT were BMF, immune cytopenia, malignancy, or immunodeficiency. Median age at HCT was 9 years (range: 2–28 years). The conditioning regimens for the final transplants were myeloablative (n = 20), reduced intensity (n = 8), or non-myeloablative (n = 2). Donors were HLA-matched related (n = 4), HLA-matched unrelated (n = 16), HLA-haploidentical (n = 2), or HLA-mismatched unrelated (n = 8). After a median follow-up of 2 years (range: 0.5–16 years), 2-year OS was 97%, and 2-year GvHD-free relapse-free survival was 73%. The hematological and immunological phenotypes resolved, and there were no new vascular events. Plasma ADA2 enzyme activity normalized in 16/17 patients tested. Six patients required more than one HCT. Conclusion HCT was an effective treatment for DADA2, successfully reversing the refractory cytopenia, as well as the vasculopathy and immunodeficiency. Clinical Implications HCT is a definitive cure for DADA2 with > 95% survival.

Background There is no information on the impact of donor type in allogeneic hematopoietic stem cell transplantation (HCT) using homogeneous graft-versus-host (GVHD) prophylaxis with post-transplant cyclophosphamide (PTCy) in acute lymphoblastic leukemia (ALL). Methods We retrospectively analyzed outcomes of adult patients with ALL in CR1 that had received HCT with PTCy as GVHD prophylaxis from HLA-matched sibling (MSD) (n = 78), matched unrelated (MUD) (n = 94) and haploidentical family (Haplo) (n = 297) donors registered in the EBMT database between 2010 and 2018. The median follow-up period of the entire cohort was 2.2 years. Results Median age of patients was 38 years (range 18–76). Compared to MSD and MUD, Haplo patients received peripheral blood less frequently. For Haplo, MUD, and MSD, the cumulative incidence of 100-day acute GVHD grade II–IV and III–IV, and 2-year chronic and extensive chronic GVHD were 32%, 41%, and 34% (p = 0.4); 13%, 15%, and 15% (p = 0.8); 35%, 50%, and 42% (p = 0.01); and 11%, 17%, and 21% (p = 0.2), respectively. At 2 years, the cumulative incidence of relapse and non-relapse mortality was 20%, 20%, and 28% (p = 0.8); and 21%, 18%, and 21% (p = 0.8) for Haplo, MUD, and MSD, respectively. The leukemia-free survival, overall survival and GVHD-free, relapse-free survival for Haplo, MUD, and MSD was 59%, 62%, and 51% (p = 0.8); 66%, 69%, and 62% (p = 0.8); and 46%, 44%, and 35% (p = 0.9), respectively. On multivariable analysis, transplant outcomes did not differ significantly between donor types. TBI-based conditioning was associated with better LFS. Conclusions Donor type did not significantly affect transplant outcome in patient with ALL receiving SCT with PTCy.

Previous observations have reported controversial conclusions regarding cell dose and survival endpoints after allogeneic hematopoietic stem cell transplantation (HSCT). We conducted a retrospective analysis on 414 adult patients (median age 54 years, range, 18-74 years) with acute myeloid leukemia (AML) in first and second complete remission. They received a T-cell replete allogeneic HSCT from haploidentical donors, using peripheral blood stem cells, between 2006-2018. Median number of infused CD34+ was 6.58 × 106 /kg (range, 2.2-31.2 × 106 /kg). Graft-vs-host disease (GVHD) prophylaxis was post-transplant cyclophosphamide in 293 patients and anti-lymphocyte serum in 121 patients. Conditioning was myeloablative in 179 patients and reduced-intensity in 235 patients. After a median follow-up of 23.3 months (range, 12.1-41.8 months), 2-year overall survival (OS) was 64.5% (95% CI 59.3%-69.7%) with leukemia-free survival (LFS) of 57.3% (95% CI 51.8%-62.7%) and non-relapse mortality (NRM) of 23.3% (95% CI 19%-27.7%). Grades III-IV acute GVHD day+100 incidence was 14.6% while extensive chronic GVHD was 14.4% at 2-years. Thirteen (3.2%) patients experienced graft failure. We found the optimal CD34+/kg threshold defining high (n = 334) vs low cell dose (n = 80) at 4.96 × 106 . Recipients of >4.96 × 106 /kg CD34+ cells experienced less NRM (Hazard ratio [HR] 0.48; 95% CI 0.30-0.76) and prolonged LFS (HR 0.63; 95% CI 0.43-0.91) and OS (HR 0.60; 95% CI 0.40-0.88) compared to those in the lower cell dose cohort. Larger cohort studies are needed to confirm these findings.

We compared outcomes of 1461 adult patients with acute lymphoblastic leukemia (ALL) receiving hematopoietic cell transplantation (HCT) from a haploidentical (n = 487) or matched unrelated donor (MUD; n = 974) between January 2005 and June 2018. Graft-versus-host disease (GVHD) prophylaxis was posttransplant cyclophosphamide (PTCy), calcineurin inhibitor (CNI), and mycophenolate mofetil (MMF) for haploidentical, and CNI with MMF or methotrexate with/without antithymoglobulin for MUDs. Haploidentical recipients were matched (1:2 ratio) with MUD controls for sex, conditioning intensity, disease stage, Philadelphia-chromosome status, and cytogenetic risk. In the myeloablative setting, day +28 neutrophil recovery was similar between haploidentical (87%) and MUD (88%) (P = .11). Corresponding rates after reduced-intensity conditioning (RIC) were 84% and 88% (P = .47). The 3-month incidence of grade II-IV acute GVHD (aGVHD) and 3-year chronic GVHD (cGVHD) was similar after haploidentical compared with MUD: myeloablative conditioning, 33% vs 34% (P = .46) for aGVHD and 29% vs 31% for cGVHD (P = .58); RIC, 31% vs 30% (P = .06) for aGVHD and 24% vs 29% for cGVHD (P = .86). Among patients receiving myeloablative regimens, 3-year probabilities of overall survival were 44% and 51% with haploidentical and MUD (P = .56). Corresponding rates after RIC were 43% and 42% (P = .6). In this large multicenter case-matched retrospective analysis, despite the limitations of a registry-based study (ie, unavailability of key elements such as minimal residual disease testing), our analysis indicated that outcomes of patients with ALL undergoing HCT from a haploidentical donor were comparable with 8 of 8 MUD transplantations.

The optimal myeloablative conditioning (MAC) for patients undergoing haploidentical hematopoietic cell transplantation (haplo-HCT) is unknown. We studied the outcomes of total body irradiation (TBI) vs chemotherapy (CT) based MAC regimens in acute myeloid leukemia (AML) patients. The study included 1008 patients who underwent first haplo-HCT with post-transplant cyclophosphamide, following TBI (N = 89, 9%) or CT (n = 919, 91%) based MAC. Patients in the TBI cohort were younger (median age, 38 vs 47 years, P < .01) and more likely to receive BM graft (57% vs 43%, P = .01). Two-year overall chronic GVHD (cGVHD) incidence was 42% vs 27% (P < .01) and extensive cGVHD incidence was 9% vs 12% (P = .33) in TBI and CT cohorts, respectively. Graft failure was reported in two (2%) TBI- and 65 (7%) CT-MAC recipients (P = .08). Death from veno-occlusive disease was reported in one (3%) TBI and 11 (3%) CT patients who died during the study period. In the multivariate analysis, TBI was associated with increased risk for overall cGVHD (hazard ratio = 1.95, 95% confidence interval:1.2-3.1, P < .01) compared to CT-based MAC. The choice of conditioning regimen did not impact relapse incidence, leukemia-free survival, non-relapse mortality, overall survival or GVHD-relapse-free survival in multivariate analysis. In conclusion, major transplant outcomes were not statistically different between TBI-based MAC and CT-based MAC in patients with AML after haplo-HCT/PTCy.

Cyclosporine A (CSA) and methotrexate (MTX) is the standard graft-versus-host disease (GVHD) prophylaxis regimen for matched sibling donor (MSD) allogeneic hematopoietic cell transplantation (allo-HCT). Recently, post-transplantation cyclophosphamide (PTCy) has been shown to be effective in GVHD prevention. In this registry-based study, we compared outcomes of 118 patients treated with PTCy and 1202 patients with CSA/MTX who underwent MSD allo-HCT for acute myelogenous leukemia. In a matched-pair analysis, PTCy was associated with a higher incidence of relapse at 2 years compared with CSA/MTX (41.1% versus 21.3%; P = .039). The incidences of day +180 grade II-IV acute GVHD and 2-year chronic GVHD were comparable in the PTCy and CSA/MTX arms (25.2% versus 25.4% [P = .90] and 42.6% versus 42.6% [P = .84], respectively). Similarly, 2-year leukemia-free survival (LFS; 54.4% versus 74.32%; P = .052), overall survival (OS; 70.6% versus 79.7%; P = .15), and GVHD-free relapse-free survival (GRFS; 38.1% versus 52.5%; P = .49) were not statistically different in the 2 arms. Our data show that GVHD prophylaxis with PTCy is feasible, resulting in similar incidences of GVHD, GRFS, LFS, and OS as seen with conventional CSA/MTX in patients undergoing allo-HCT from an MSD. The higher rate of relapse observed with PTCy needs further evaluation in a prospective study. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Survival of patients with secondary acute myeloid leukemia (sAML) is poor. Cord blood transplantation (UCBT) and non-T-cell-depleted stem cell transplantation from haploidentical donors (HAPLO) are both strategies that have shown encouraging results in patients who do not have an human leukocyte antigen (HLA)-matched sibling or unrelated donor. We retrospectively analyzed outcomes of 409 adults with sAML receiving either UCBT (n = 163) or HAPLO (n = 246) in EBMT centers. Myelodysplastic syndrome (MDS) or myeloproliferative disorder (MPD) was the antecedent diagnosis in 79% of UCBT and 85% of HAPLO recipients. In multivariate analysis, UCBT was associated with higher risk of grade II–IV acute GVHD (HR 1.9, p = 0.009) and lower GHVD-free-relapse-free-survival (GRFS) (HR 1.57, p = 0.007) compared to HAPLO. Chronic-GVHD, RI, NRM, LFS, and OS were not statistically different between the two. Early disease stage at transplant was independently associated with lower RI and NRM and higher OS and LFS. These results indicate that HAPLO is associated with better GRFS and lower aGvHD compared to UCBT in patients with sAML and that UCBT can be a valid alternative for sAML patients who lack a matched sibling, a proper haploidentical or an unrelated donor.

The optimal myeloablative conditioning (MAC) for patients undergoing haploidentical hematopoietic cell transplantation (haplo-HCT) is unknown. We studied the outcomes of total body irradiation (TBI)-based versus chemotherapy (CT)-based MAC regimens in patients with acute lymphoblastic leukemia (ALL). The study included 427 patients who underwent first haplo-HCT with post-transplantation cyclophosphamide (PTCy), following TBI-based (n = 188; 44%) or CT-based (n = 239; 56%) MAC. The median patient age was 32 years. Fludarabine-TBI (72%) and thiotepa-busulfan-fludarabine (65%) were the most frequently used TBI- and CT-based regimens, respectively. In the TBI and CT cohorts, 2-year leukemia-free survival (LFS) was 45% versus 37% (P = .05), overall survival (OS) was 51% versus 47% (P = .18), relapse incidence (RI) was 34% versus 32% (P = .44), and nonrelapse mortality (NRM) was 21% versus 31% (P < .01). In the multivariate analysis, TBI was associated with lower NRM (hazard ratio [HR], 0.53; 95% confidence interval [CI], 0.33 to 0.86; P = .01), better LFS (HR, 0.71; 95% CI, 0.52 to 0.98; P =.04), and increased risk for grade II-IV acute graft-versus-host disease (GVHD) (HR, 1.59; 95% CI, 1.08 to 2.34; P = .02) compared with CT-based MAC. The type of conditioning regimen did not impact RI, chronic GVHD, OS, or GVHD-free, relapse-free survival after adjusting for transplantation-related variables. TBI-based MAC was associated with lower NRM and better LFS compared with CT-based MAC in patients with ALL after haplo-HCT/PTCy.

Outcomes after unmanipulated haploidentical stem cell transplantation (Haplo) and after unrelated cord blood transplantation (UCBT) are encouraging and have become alternative options to treat patients with high-risk acute leukemia without human leukocyte antigen (HLA) matched donor. We compared outcomes after UCBT and Haplo in adults with de novo acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Median follow-up was 24 months. Analysis was performed separately for patients with AML, n = 918 (Haplo = 360, UCBT = 558) and ALL, n = 528 (Haplo = 158 and UCBT = 370). UCBT was associated with delayed engraftment and higher graft failure in both AML and ALL recipients. In multivariate analysis, UCBT was associated with lower incidence of chronic graft-vs-host disease both in the AML group (hazard ratio (HR) = 0.63, P = 0.008) and in the ALL group (HR = 0.58, P = 0.01). Not statistically significant differences were observed between Haplo and UCBT for relapse incidence (HR = 0.95, P = 0.76 for AML and HR = 0.82, P = 0.31 for ALL), non-relapse mortality (HR = 1.16, P = 0.47 for AML and HR = 1.23, P = 0.23 for ALL) and leukemia-free survival (HR 0.78, P = 0.78 for AML and HR = 1.00, P = 0.84 for ALL). There were no statistically differences on main outcomes after unmanipulated Haplo and UCBT, and both approaches are valid for acute leukemia patients lacking a HLA matched donor. Both strategies expand the donor pool for patients in need.

The use of unmanipulated graft is increasingly adopted in the setting of allogeneic hematopoietic stem cell transplantation from haploidentical family donors (haplo-SCT) in acute leukemia (AL). We analyzed the outcome of 229 adult patients with de novo AL, who received an unmanipulated haploidentical transplant as their first allo-SCT between 2007 and 2011. Median follow-up was 30 months. Disease status at transplant was: first complete remission (CR1) for 77, second CR (CR2) for 56, and advanced for 96 patients. One hundred and seventy-one patients received in vivo T-cell depletion by monoclonal antibodies (75%). The 60-day cumulative incidence (CI) of engraftment was 93 +/- 2%. The 100-day CI of acute graft-versus-host disease (GvHD) was 32 +/- 3% for grade II-IV, 12 +/- 3% for grade III-IV. The 3-year CI of chronic GvHD was 34 +/- 3%. The 3-year CI of non-relapse mortality was 31 +/- 4% with in vivo T-cell depletion and 17 +/- 5% without. At 3 years, for patients transplanted in CR1, CR2 or advanced disease leukemia-free survival was 44 +/- 6, 42 +/- 7 and 12 +/- 3%, overall survival was 55 +/- 6, 51 +/- 7 and 14 +/- 4% and CI of relapse was 32 +/- 6, 24 +/- 6 and 61 +/- 5%, respectively. These data suggest that unmanipulated haplo-SCT is a valid treatment option for adult AL patients in complete remission lacking a matched donor.

Autologous stem-cell transplantation (ASCT) has emerged as the standard approach in patients with multiple myeloma, although it is unlikely to achieve cure. Thalidomide maintenance and non-myeloablative allogeneic transplantation (NST) may increase complete remission (CR) rate and increase overall survival. In this study, 35 ASCT and 10 NST were performed in 33 patients. Patients, who were resistant or relapsed following ASCT, underwent NST if they had an HLA-matched sibling, otherwise treated with a second ASCT. Thalidomide was started as maintenance after ASCT. After first transplantation, three patients underwent second ASCT and 10 patients underwent NST. Following first transplantation, CR rate was 39% and increased to 60% (overall response 93%) with addition of thalidomide, bortezomib, and second transplantation. CR was durable in 14 (42%) patients. During a median follow-up of 24 months, 18 patients progressed and nine patients died. The 100-d transplant-related mortality was

Twenty one relapsed/refractory myeloma patients who failed thalidomide and dexamethasone received VTD combination treatment at our institution. Median age was 57 years (range, 43–80) and median number of previous lines of therapy was 3. Ten had prior autologous SCT and one had reduced intensity allogeneic SCT. All patients had active and measurable disease. Treatment plan was as follows: bortezomib iv on 1st, 4th, 8th and 11th days of a 21-day cycle (up to 8 cycles), dexamethasone 40 mg iv before each bortezomib dose and thalidomide 100 mg each evening. Elderly (≥65 year-old, n=6, 4 of whom also had grade 1 peripheral neuropathy (PN)) and two younger patients with grade 1 PN received bortezomib 1.5 mg iv (low dose) and thalidomide 100 mg each evening only during 10 day rest periods after bortezomib treatments (sequential, n=8). All other patients received bortezomib 1.75 mg iv (higher dose) and thalidomide 100 mg each evening (concomitant, n=13). The patients received a median of 6 cycles of the treatment (range, 2–8 cycles). DVT prophylaxis was aspirin 100 mg po qd. All patients who had at least 2 cycles of the treatment were evaluable for response according to EBMT criteria and 16 (76%) were the responders: 4 CR, 9 PR (5 VGPR by IMWG criteria), 3 MR. Five were the progressive ones. Among these, 8 went on to receive autologous and 2 had reduced intensity allogeneic SCT immediately after planned VTD treatment. Median number of cycles to the best response was 6 cycles. Among responders who did not go on to transplant, duration of response lasted from 2 to 15 months. Three patients had pneumonia (14%), three had varicella zoster infection (14%). No case of DVT was recorded. No treatment related deaths occurred. Four patients had grade 3 toxicity (PN, n=2; fatigue, n=2; and pancytopenia, n=1). Thalidomide was discontiuned in two patients after 2 cycles and in one patient after 3 cycles owing to grade 3 toxicities of fatigue and/or PN that were down-graded and reversible after cessation of thalidomide. Bortezomib was temporarily discontinued in one patient owing to grade 3 pancytopenia and re-started at the dose of 1.5 mg iv. The most frequently observed adverse effects were as follows: PN, n=14 (67%); fatigue, n=13 (62%); anemia, n=13 (62%); thrombocytopenia, n=10 (48%); leucopenia, n=9 (43%); constipation, n=6 (28%); peripheral edema, n=5 (24%); insomnia, n=3 (14%). Elderly and the patients with low-grade PN who received low dose bortezomib and sequential thalidomide experienced less PN (no new cases except two patients with grade 1 PN were upgraded to grade 2 and 3) compared to the patients who received higher dose bortezomib and concomitant thalidomide treatment (newly developed PN in 8: grade 1, n=6; grade 2, n=1; grade 3, n=1). Response rates were comparable between two groups (concomitant, 77% versus sequential, 75%). We conclude that VTD combination may induce high quality responses with acceptable toxicity in a significant proportion of relapsed/refractory myeloma patients with progression after thalidomide, dexamethasone and transplantation. This may be explained by synergism and/or additive effect. Low dose bortezomib and sequential thalidomide are well tolerated with less PN by elderly and the patients with low-grade PN. Increased incidences of infections may justify antibacterial and antiviral prophylaxis.