Engraftment, clinical, and molecular follow-up of patients with multiple myeloma who were reinfused with highly purified CD34+ cells to support single or tandem high-dose chemotherapy

Use of Backup Stem Cells for Stem Cell Boost and Second Transplant in Patients with Multiple Myeloma Undergoing Autologous Stem Cell Transplantation

Autologous hematopoietic stem cell transplantation (ASCT) is a standard treatment for multiple myeloma (MM). Consensus guidelines recommend collecting sufficient stem cells in case there is a need for stem cell boost for delayed/poor engraftment or for future second ASCT. However, collecting and storing backup stem cells in all patients requires significant resources and cost, and the rates of backup stem cell utilization are not well studied. We sought to examine the utilization of backup stem cells (BSCs) in patients with MM undergoing ASCT. Patients with MM aged ≥18 years old who underwent first ASCT at our institution from January 2010 through December 2015 and collected sufficient stem cells for at least 2 transplants were included in this single-center retrospective study. This timeframe was selected to allow for adequate follow-up. A total of 393 patients were included. The median age was 58 years (range, 25-73). After a median follow-up of 6 years, the median progression-free survival (PFS) of the cohort was 3 years. Sixty-one percent (n = 240) of patients progressed or relapsed. Chemotherapy-based mobilization was used in almost all patients (98%). The median total CD34+ cells collected was 18.2 × 106/kg (range, 3.4-112.4). A median of 5.7 × 106 CD34+ cells/kg (range, 1.8-41.9) was infused during the first ASCT, and a median of 10.1 × 106 CD34+ cells/kg (range, 1.5-104.5) was cryopreserved for future use. Of the patients, 6.9% (n = 27) used backup stem cells, with 2.3% (n = 10) using them for stem cell boost, 4.6% (n = 18) for a second salvage ASCT, including 1 patient for both stem cell boost and second ASCT. Rates of backup stem cell use among patients aged <60, 60-69, and ≥70 years were 7.8%, 5.7%, and 5.9%, respectively. There was a trend toward higher rates of backup stem cell use for second ASCT in patients who were younger, had suboptimal disease control at time of first ASCT, and longer PFS. The median dose of stem cell boost given was 5.6 × 106 CD34+ cells/kg (range, 1.9-20). The median time from stem cell boost to neutrophil, hemoglobin, and platelet engraftment was 4 (range, 2-11), 15 (range, 4-34), and 12 (range, 0-34) days, respectively. Lower CD34+ dose and older age at time of ASCT predicted need for stem cell boost. With new salvage therapies for relapsed MM, the rates of second ASCT are very low. The low rates of use suggest that institutional policies regarding universal BSC collection and long-term storage should be reassessed and individualized. However, need for stem cell boost in 2.3% of patients may present a challenge to that.

Stem Cell Mobilization and Autograft Minimal Residual Disease Negativity with Novel Induction Regimens in Multiple Myeloma

Autologous stem cell transplantation (ASCT) remains the standard of care for transplantation-eligible patients with multiple myeloma (MM). Bortezomib with lenalidomide and dexamethasone (VRD) is the most common triplet regimen for newly diagnosed MM in the United States. Carfilzomib with lenalidomide and dexamethasone (KRD) has shown promising efficacy and may supplant VRD. We compared stem cell yields and autograft minimal residual disease (MRD)-negativity after VRD and KRD induction. Deeper responses (ie, very good partial response or better) were more common with KRD. Precollection bone marrow (BM) cellularity, interval from the end of induction therapy to start of stem cell collection, and method of stem cell mobilization were similar for the 2 cohorts. Days to complete collection was greater with KRD (2.2 days, versus 1.81 days with VRD), which more often required ≥3 days of apheresis. Precollection viable CD34⁺ cell content was greater with VRD, as was collection yield (11.11 × 10⁶, versus 9.19 × 10⁶ with KRD). Collection failure (defined as <2 × 10⁶ CD34⁺ cells/kg) was more frequent with KRD (5.4% versus .7% with VRD). The difference in stem cell yield between VRD and KRD is associated with the degree of lenalidomide exposure. Age ≥70 years predicted poorer collection for both cohorts. Stem cell autograft purity/MRD-negativity was higher with KRD (81.4%, versus 57.1% with VRD). For both cohorts, MRD-negativity was attained in a larger fraction of autografts than in precollection BM. For patients proceeding to ASCT, the time to neutrophil/platelet engraftment was comparable in the 2 study arms. In summary, our data demonstrate that KRD induces deeper clinical responses and greater autograft purity than VRD without compromising stem cell yield or post-transplantation engraftment kinetics.

Stem Cell Transplantation for Multiple Myeloma

BACKGROUND

Multiple myeloma (MM) is the second most common hematologic malignancy, affecting approximately 14,000 new patients in the United State per year. The median overall survival is 5 years, and cure is a realistic goal for only a small minority of patients.

METHODS

A review of the literature was conducted that focused on treatment strategies for MM involving administration of high doses of chemotherapy followed by autologous or allogeneic hematopoietic stem cell transplant.

RESULTS

For over three decades, the standard treatment for MM has been a regimen of melphalan and prednisone (MP). Complete responses (CRs) have been rare, and 50% of patients have had disease that was resistant to treatment with MP. Attempts have been made to improve the outcome of MM by administering other combinations of standard doses of chemotherapy, but these treatments are equivalent in terms of overall survival. For patients who are candidates, high-dose therapy followed by autologous stem cell transplantation results in higher CR rates and improved long-term survival compared to treatment with standard doses of chemotherapy alone. While this strategy represents an advance in the treatment of MM, evidence-based reviews indicate that there are a number of issues to consider regarding the induction therapy, the collection of stem cells, and the timing, type, and number of high-dose therapies to use in this type of treatment strategy.

CONCLUSIONS

Advances have been made in autologous transplantation, allogeneic transplantation, anti-MM agents, and immunotherapy for MM. Combining these different strategies to achieve synergistic responses is an exciting possibility.

Autologous haematopoietic stem cell mobilisation in multiple myeloma and lymphoma patients: a position statement from the European Group for Blood and Marrow Transplantation

Autologous haematopoietic SCT with PBSCs is regularly used to restore BM function in patients with multiple myeloma or lymphoma after myeloablative chemotherapy. Twenty-eight experts from the European Group for Blood and Marrow Transplantation developed a position statement on the best approaches to mobilising PBSCs and on possibilities of optimising graft yields in patients who mobilise poorly. Choosing the appropriate mobilisation regimen, based on patients' disease stage and condition, and optimising the apheresis protocol can improve mobilisation outcomes. Several factors may influence mobilisation outcomes, including older age, a more advanced disease stage, the type of prior chemotherapy (e.g., fludarabine or melphalan), prior irradiation or a higher number of prior treatment lines. The most robust predictive factor for poor PBSC collection is the CD34(+) cell count in PB before apheresis. Determination of the CD34(+) cell count in PB before apheresis helps to identify patients at risk of poor PBSC collection and allows pre-emptive intervention to rescue mobilisation in these patients. Such a proactive approach might help to overcome deficiencies in stem cell mobilisation and offers a rationale for the use of novel mobilisation agents.

Plasmonic nanobubbles as tunable cellular probes for cancer theranostics

This review is focused on a novel cellular probe, the plasmonic nanobubble (PNB), which has the dynamically tunable and multiple functions of imaging, diagnosis, delivery, therapy and, ultimately, theranostics. The concept of theranostics was recently introduced in order to unite the clinically important stages of treatment, namely diagnosis, therapy and therapy guidance, into one single, rapid and highly accurate procedure. Cell level theranostics will have far-reaching implications for the treatment of cancer and other diseases at their earliest stages. PNBs were developed to support cell level theranostics as a new generation of on-demand tunable cellular probes. A PNB is a transient vapor nanobubble that is generated within nanoseconds around an overheated plasmonic nanoparticle with a short laser pulse. In the short term, we expect that PNB technology will be rapidly adaptable to clinical medicine, where the single cell resolution it provides will be critical for diagnosing incipient or residual disease and eliminating cancer cells, while leaving healthy cells intact. This review discusses mechanisms of plasmonic nanobubbles and their biomedical applications with the focus on cancer cell theranostics.

Collection of peripheral blood stem cells in new patients with myeloma receiving minimal or no prior cytoreductive therapy

The aim of the study was to evaluate whether adequate stem cells (CD34+) could be harvested at presentation in myeloma patients such that high dose melphalan (HDM) with autologous stem cell rescue can be offered as primary therapy. The regimes either involved no prior cytoreductive chemotherapy (steroids only, n = 31) or a single course of VAD (n = 22). The median number of CD34 cells collected with steroids was 1.3 x 10(6) (0.2-5.6) compared to 4.6 x 10(6) (0.3-19.2) cells/kg with VAD (P < 0.0001). We conclude that it is possible to collect stem cells from myeloma patients at presentation with minimal prior therapy. Using this strategy, of a single prior course of chemotherapy followed by immediate harvest, it is feasible to offer early high-dose therapy in clinical situations where this is important.

Efficacy and safety of busulfan-based conditioning regimens for multiple myeloma

Multiple myeloma is a malignancy of B cells characterized by accumulation of abnormal plasma cells in the bone marrow. In the past 20 years, the use of high-dose therapies and novel agents has resulted in significant and meaningful improvements in survival. Autologous stem cell transplantation (auto-SCT) following a high-dose melphalan-conditioning regimen represents the standard of care for younger patients as well as older patients with a good performance status. A number of strategies have been proposed to improve the outcome of auto-SCTs, including the incorporation of new agents such as thalidomide, lenalidomide, and bortezomib into the induction regimen administered before auto-SCT; the administration of maintenance therapy after auto-SCT; the incorporation of novel agents into chemotherapeutic regimens after transplantation as consolidation therapy; and the use of reduced-intensity allogeneic transplantation after an initial autograft. Although these approaches have demonstrated some success in improving responses after auto-SCT, none of these strategies are curative. An additional strategy to improve outcomes after auto-SCT is to enhance the immediate pretransplant conditioning regimens by either increasing the dose of melphalan or by incorporating novel agents, such as busulfan. This literature review focuses on the efficacy and safety of busulfan-based conditioning regimens for auto-SCT in patients with multiple myeloma.

Autologous Hematopoietic Stem Cell Transplantation for Multiple Myeloma without Cryopreservation

High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation is considered the standard of care for multiple myeloma patients who are eligible for transplantation. The process of autografting comprises the following steps: control of the primary disease by using a certain induction therapeutic protocol, mobilization of stem cells, collection of mobilized stem cells by apheresis, cryopreservation of the apheresis product, administration of high-dose pretransplant conditioning therapy, and finally infusion of the cryopreserved stem cells after thawing. However, in cancer centers that treat patients with multiple myeloma and have transplantation capabilities but lack or are in the process of acquiring cryopreservation facilities, alternatively noncryopreserved autologous stem cell therapy has been performed with remarkable success as the pretransplant conditioning therapy is usually brief.

High-dose therapy and autologous peripheral blood stem cell transplantation in patients with multiple myeloma

Since its introduction in 1983, high-dose therapy followed by autologous peripheral blood stem cell transplantation is a pillar of the treatment of patients with multiple myeloma. In the last decades, a multitude of clinical trials helped to improve strategies based on high-dose therapy and autologous stem cell transplantation resulting in a continuously prolongation of overall survival of patients. In this chapter we will review the progress, which has been made in order to enhance the mobilisation of autologous stem cells and increase the effectiveness of this treatment.

[Advances and perspectives in treatment for refractory neuropathies with special reference to immune-mediated neuropathies and Crow-Fukase syndrome]

There are significant advances in immune-modulating treatments for Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) in the past 20 years. GBS, however, is still a serious disease with a mortality rate of 8% and 20% of the patients being unable to walk independently a year after onset For CIDP and related disorders such as multifocal motor neuropathy, and demyeinating neuropathy with anti-myelin-associated-glycoprotein (MAG) antibody, treatments should be based on individual pathophysiology. Rituximab could be a promising agent for the subtypes of CIDP refractory to conventional immune treatments. Crow-Fukase syndrome is a rare cause of demyelinating neuropathy with multiorgan involvement Overproduction of vascular endothelial growth factor (VEGF), probably mediated by monoclonal proliferation of plasma cells, is likely to be responsible for most of the characteristic symptoms. There is no established treatment regimen for Crow-Fukase syndrome. In appropriate candidates, high-dose chemotherapies with autologous peripheral blood stem cell transplantation is highly recommended, because this treatment could result in obvious improvement in neuropathy as well as other symptoms. Indication of this treatment has not yet been established, and long-term prognosis is unclear at present. Treatments that should be considered as future therapy against Crow-Fukase syndrome include thalidomide, and anti-VEGF monoclonal antibody (bevacizumab).

Plerixafor and G-CSF versus placebo and G-CSF to mobilize hematopoietic stem cells for autologous stem cell transplantation in patients with multiple myeloma

This phase 3, multicenter, randomized (1:1), double-blind, placebo-controlled study evaluated the safety and efficacy of plerixafor with granulocyte colony-stimulating factor (G-CSF) in mobilizing hematopoietic stem cells in patients with multiple myeloma. Patients received G-CSF (10 microg/kg) subcutaneously daily for up to 8 days. Beginning on day 4 and continuing daily for up to 4 days, patients received either plerixafor (240 microg/kg) or placebo subcutaneously. Starting on day 5, patients began daily apheresis for up to 4 days or until more than or equal to 6 x 10(6) CD34(+) cells/kg were collected. The primary endpoint was the percentage of patients who collected more than or equal to 6 x 10(6) CD34(+) cells/kg in less than or equal to 2 aphereses. A total of 106 of 148 (71.6%) patients in the plerixafor group and 53 of 154 (34.4%) patients in the placebo group met the primary endpoint (P < .001). A total of 54% of plerixafor-treated patients reached target after one apheresis, whereas 56% of the placebo-treated patients required 4 aphereses to reach target. The most common adverse events related to plerixafor were gastrointestinal disorders and injection site reactions. Plerixafor and G-CSF were well tolerated, and significantly more patients collected the optimal CD34(+) cell/kg target for transplantation earlier compared with G-CSF alone. This study is registered at www.clinicaltrials.gov as #NCT00103662.

Phase I/II clinical trial of sequential subcutaneous and intravenous delivery of dendritic cell vaccination for refractory multiple myeloma using patient-specific tumour idiotype protein or idiotype (VDJ)-derived class I-restricted peptides

Fifteen multiple myeloma (MM) patients who had failed maintenance therapy after tandem autologous stem cell transplantation underwent anti-idiotype (Id) vaccination with dendritic cells (DCs). CD14(+)-derived DCs were loaded with the autologous Id as whole protein (=6) or Id-derived class I-restricted peptides (=9) and keyhole limpet hemocyanin (KLH). Vaccination consisted of three subcutaneous (sc) and two intravenous injections of increasing DC doses at 2 weeks interval. DC therapy was well tolerated. Most patients developed both humoral and T-cell responses to KLH, suggesting immunocompetence. Eight of 15 patients developed an Id-specific T-cell proliferative response, 8/15 increased interferon-gamma-secreting T cells and 4/15 showed an Id-positive delayed-type hypersensitivity test. Anti-Id cytotoxic T-lymphocyte precursors increased after DC vaccination in 2/2 evaluable patients. A more robust T-cell response was observed after sc DC injections and increased Id-specific T-cell proliferation was found up to 1 year after vaccination. VDJ-derived peptides were as effective as the whole protein in stimulating T-cell responses. Clinically, 7/15 patients have stable disease after a median follow-up of 26 months, one patient achieved durable partial remission after 40 months, and seven patients progressed. In conclusion, sc injections of cryopreserved Id-pulsed DCs were safe and, in contrast with intravenous administrations, induced anti-MM T-cell responses.

Positive selection and transplantation of autologous highly purified CD133(+) stem cells in resistant/relapsed chronic lymphocytic leukemia patients results in rapid hematopoietic reconstitution without an adequate leukemic cell purging

We assessed the capacity of positively selected autologous CD133(+) hematopoietic stem cells (HSCs) to reconstitute lymphomyelopoiesis in chronic lymphocytic leukemia (CLL) patients receiving myeloablative chemotherapy. Ten resistant/relapsed CLL patients underwent HSC mobilization with chemotherapy and granulocyte-colony stimulating factor (G-CSF). Positive selection of circulating CD133(+) HSCs was performed by immunomagnetic technique. Highly purified HSCs were reinfused after busulphan/melphalan myeloablative treatment. A median number of 4.2 x 10(6) CD34(+) cells/kg and of 3.14 x 10(6) CD133(+) cells/kg were collected. Immunomagnetic selection resulted in the reinfusion of a median number of 2.45 x 10(6) CD133(+) cells/kg (median purity: 94.8%; median recovery: 84%) and 2.4 x 10(6) CD34(+) cells/kg (median purity: 93%; median recovery: 71%). HSC selection resulted in a median T cell and CD19(+)/CD5(+) cell depletion of 3.85 log and 2.8 log, respectively. At the molecular level, however, 7 of 8 valuable purified HSC fractions were contaminated by leukemic cells. All CLL patients showed rapid and sustained myeloid engraftment after reinfusion of purified CD133(+) cells. Immunologic reconstitution was comparable to that routinely observed in patients reinfused with unmanipulated leukapheresis products and no late infectious complications were observed. With a median follow-up of 28 months for transplanted patients, 5 patients are in clinical complete remission, 3 are in partial remission, and 1 is in progression. In conclusion, the reinfusion of highly purified CD133(+) HSCs allowed the rapid and sustained recovery of hematopoiesis after myeloablative treatment in resistant/relapsed CLL patients. However, the purging potential of positive selection of CD133(+) cells is not adequate to achieve tumor-free autografts.

Molecular purging of multiple myeloma cells by ex-vivo culture and retroviral transduction of mobilized-blood CD34+ cells

Background

Tumor cell contamination of the apheresis in multiple myeloma is likely to affect disease-free and overall survival after autografting.

Objective

To purge myeloma aphereses from tumor contaminants with a novel culture-based purging method.

Methods

We cultured myeloma-positive CD34⁺ PB samples in conditions that retained multipotency of hematopoietic stem cells, but were unfavourable to survival of plasma cells. Moreover, we exploited the resistance of myeloma plasma cells to retroviral transduction by targeting the hematopoietic CD34⁺ cell population with a retroviral vector carrying a selectable marker (the truncated form of the human receptor for nerve growth factor, ΔNGFR). We performed therefore a further myeloma purging step by selecting the transduced cells at the end of the culture.

Results

Overall recovery of CD34⁺ cells after culture was 128.5%; ΔNGFR transduction rate was 28.8% for CD34⁺ cells and 0% for CD138-selected primary myeloma cells, respectively. Recovery of CD34⁺ cells after ΔNGFR selection was 22.3%. By patient-specific Ig-gene rearrangements, we assessed a decrease of 0.7–1.4 logs in tumor load after the CD34⁺ cell selection, and up to 2.3 logs after culture and ΔNGFR selection.

Conclusion

We conclude that ex-vivo culture and retroviral-mediated transduction of myeloma leukaphereses provide an efficient tumor cell purging.

Effect of CD34 cell dose on hematopoietic reconstitution and outcome in 508 patients with multiple myeloma undergoing autologous peripheral blood stem cell transplantation

BACKGROUND

We analyzed the hematopoietic reconstitution and outcome of 508 patients with multiple myeloma (MM) with respect to the number of CD34+ cells reinfused at our center.

PATIENTS AND METHODS

Each cohort of 390 patients (unselected CD34+ cell transplant) and 118 patients (CD34+ selected transplant) was divided into four subgroups. Among the 390 transplantations, 86 patients received a high dose (HD-) of > or =6.50 x 10(6) unselected CD34+ cells/kg, 116 patients a low dose (LD-) of <3.00 x 10(6) CD34+ cells/kg. Among the patients treated with CD34+ selected PBSC, 34 received > or =6.50 x 10(6) CD34+ cells/kg (HD+) and 16 <3.00 x 10(6) CD34+ cells/kg (LD+).

RESULTS

HD- patients experienced a reduced median time to leukocyte (13 d vs. 14 d) (P < 0.001) and platelet reconstitution >20 x 10(9)/L (10 d vs. 12 d) (P < 0.001). Similarly, HD+ showed a reduced median time to leukocyte (12 d vs. 15 d) (P < 0.001) and platelet recovery >20 x 10(9)/L (10 d vs. 11 d) (P = 0.058). CD34+ cell-dose was significant for long-term platelet recovery at day 360 (unselected transplant P = 0.015, selected transplant P = 0.023). Number of transplanted CD34+ cells had no significant impact on transplant related mortality, overall survival or CR/PR rates within 100 d. In terms of supportive care the differences of high-/low-dose grafts were minimal.

CONCLUSIONS

These results confirm that high doses of CD34+ PBSC shorten hematopoietic reconstitution and reduce hospitalization. Nevertheless secure engraftment results from transplantation of 2.00-3.00 x 10(6) CD34+ cells/kg. As 60% of our pretreated patients are able to collect > or =5.00 x 10(6) CD34+ cells/kg within a single leukapheresis, division into two or more freezing bags allows safe tandem transplantation in the majority of MM patients.

A novel pattern of transaminase elevation associated with autologous transplant for neuroblastoma

To determine the pattern and degree of hepatic transaminitis experienced by children undergoing autologous transplantation for neuroblastoma. Sixty-four children with high-risk neuroblastoma received an autologous transplant with cyclophosphamide, etoposide, and carboplatin conditioning. Forty-eight went on to receive a second transplant with M and TBI conditioning. Charts were reviewed for evidence of hepatic regimen-related toxicity. A high rate of transaminitis was observed after both regimens. In each transplant, there was an early period of transaminitis during conditioning, from which patients recovered, followed by a second period of transaminase elevation. The degree of elevation was not associated with age, whether the administered dose was calculated based on a per kg or per M(2) basis or the presence of regimen-related severe mucositis. Elevated transaminases at admission were not associated with maximal hepatotoxicity during the first transplant although there was an association in the second transplant. However, the magnitude of transaminase elevation was less in the second transplant. VOD occurred in one and three patients in transplants 1 and 2, respectively. Both conditioning regimens were associated with an early and late elevation of transaminases without significant cholestasis. This biphasic pattern of transaminitis has not been reported previously. The high prevalence of transaminase elevation at time of both transplants was not associated with an increased incidence of VOD. We conclude that elevated transaminases should not preclude proceeding to a first or second autologous transplant with these regimens.

FGFR3 as a therapeutic target of the small molecule inhibitor PKC412 in hematopoietic malignancies

Reccurent chromosomal translocation t(4;14) (p16.3;q32.3) occurs in patients with multiple myeloma (MM) and is associated with ectopic overexpression of fibroblast growth factor receptor 3 (FGFR3) that sometimes may contain the activation mutations such as K650E thanatophoric dysplasia type II (TDII). Although there have been significant advances in therapy for MM including the use of proteasome inhibitors, t(4;14) MM has a particularly poor prognosis and most patients still die from complications related to their disease or therapy. One potential therapeutic strategy is to inhibit FGFR3 in those myeloma patients that overexpress the receptor tyrosine kinase due to chromosomal translocation. Here we evaluated PKC412, a small molecule tyrosine kinase inhibitor, for treatment of FGFR3-induced hematopoietic malignancies. PKC412 inhibited kinase activation and proliferation of hematopoietic Ba/F3 cells transformed by FGFR3 TDII or a TEL-FGFR3 fusion. Similar results were obtained in PKC412 inhibition of several different t(4;14)-positive human MM cell lines. Furthermore, treatment with PKC412 resulted in a statistically significant prolongation of survival in murine bone marrow transplant models of FGFR3 TDII-induced pre-B cell lymphoma, or a peripheral T-cell lymphoma associated TEL-FGFR3 fusion-induced myeloproliferative disease. These data indicate that PKC412 may be a useful molecularly targeted therapy for MM associated with overexpression of FGFR3, and perhaps other diseases associated with dysregulation of FGFR3 or related mutants.

Optimizing the use of anti-interleukin-6 monoclonal antibody with dexamethasone and 140 mg/m2 of melphalan in multiple myeloma: results of a pilot study including biological aspects

Interleukin-6 (IL-6) is a major survival factor for multiple myeloma (MM) cells preventing apoptosis induced by dexamethasone (DEX) or chemotherapy. In all, 24 consecutive patients with MM in first-line therapy received DEX for 4 days, followed by melphalan (HDM: 140 mg/m2) and autologous stem cell transplantation (ASCT). The anti-IL-6 monoclonal antibody (mAb) (B-E8) was given till haematological recovery, starting 1 day before DEX. Results were historically compared to MM patients treated with HDM 140 and 200 mg/m2. Our results show (1) that B-E8 was able to fully neutralize IL-6 activity in vivo before and after HDM as shown by inhibition of C reactive protein (CRP) production; (2) no haematological toxicity; (3) a significant reduction of mucositis and fever; (4) a median event-free survival of 35 months and an overall survival of 68.2% at 5 years with a median follow-up of 72 months; and (5) the overall daily IL-6 production progressively increased on and after 7 days post-HDM, with the increased serum CRP levels. In the 5/24 patients with uncontrolled CRP production, a large IL-6 production was detected (320 microg/day) that could not possibly be neutralized by B-E8. These data show the feasibility to neutralize IL-6 in vivo with anti-IL-6 mAb in the context of HDM.

Modified total body irradiation as a planned second high-dose therapy with stem cell infusion for patients with bone-based malignancies

PURPOSE

To estimate the maximum tolerated dose of hyperfractionated total marrow irradiation (TMI) as a second consolidation after high-dose chemotherapy with autologous or syngeneic blood stem cell transfusion for patients with bone/bone marrow-based malignant disease.

PATIENTS AND METHODS

Fifty-seven patients aged 3-65 years (median, 45 years), including 21 with multiple myeloma, 24 with breast cancer, 10 with sarcoma, and 2 with lymphoma, were treated with 1.5 Gy administered twice daily to a total dose of 12 Gy (n = 27), 13.5 Gy (n = 12), and 15 Gy (n = 18). Median time between the 2 transplants was 105 days (range, 63-162 days).

RESULTS

All patients engrafted neutrophils (median, Day 11; range, Day 9-23) and became platelet independent (median, Day 9; range, Day 7-36). There were 5 cases of Grade 3-4 regimen-related pulmonary toxicity, 1 at 12 Gy, and 4 at 15 Gy. Complete responses, partial responses, and stabilizations were achieved in 33%, 26%, and 41% of patients, respectively. Kaplan-Meier estimates of 5-year progression-free survival and overall survival for 56 evaluable patients are 24% and 36%, respectively. Median time of follow-up among survivors was 96 months (range, 77-136 months).

CONCLUSION

Total marrow irradiation as a second myeloablative therapy is feasible. The estimated maximum tolerated dose for TMI in a tandem transplant setting was 13.5 Gy. Because 20% of patients are surviving at 8 years free of disease, further studies of TMI are warranted.

The significance of minimal residual disease in stem cell grafts and the role of purging: is it better to purge in vivo or in vitro?

Contamination of autologous graft by tumor, in addition to incomplete tumor eradication, can partly explain why relapse remains the commonest cause of treatment failure after autologous stem cell transplantation (ASCT) in patients with malignant hematologic disorders. Monitoring of minimal residual disease (MRD) is now recognized as an important diagnostic tool for assessment either of the response to treatments aimed at maximal cytoreduction and the individual risk of relapse. In order to improve cure rates, many strategies to achieve in vivo or in vitro reduction, if not eradication, of residual disease have been proposed. We discuss the significance of MRD and the role of purging in the ASCT setting, focusing on acute myeloid leukemia, chronic myeloid leukemia, multiple myeloma and follicular lymphoma.

Superiority of thalidomide and dexamethasone over vincristine-doxorubicindexamethasone (VAD) as primary therapy in preparation for autologous transplantation for multiple myeloma

The aim of the present study was to compare thalidomide-dexamethasone (Thal-Dex) and vincristine-doxorubicin-dexamethasone (VAD) as primary therapy in preparation for autologous peripheral blood stem-cell (PBSC) transplantation for multiple myeloma (MM). For this purpose, we performed a retrospective matched case-control analysis of 200 patients who entered 2 consecutive studies from 1996 to 2004 and received Thal-Dex (n = 100) or VAD (n = 100) administered for 4 months before collection of PBSCs and autologous transplantation. Matching criteria included age, clinical stage, and serum beta2-microglobulin levels. In comparison with VAD, Thal-Dex resulted in a significantly higher response rate (52% versus 76%, respectively; P < .001) and effected more profound reduction in myeloma cell mass of both immunoglobulin G (IgG; P = .02) and IgA (P = .03) type. More frequent toxicities included nonfatal deep vein thrombosis with Thal-Dex (15%) and granulocytopenia with VAD (12%). In each of the 2 treatment groups, 91% of patients proceeded to PBSC mobilization. The median number of collected CD34+ cells was 7.85 x 10(6)/kg in the Thal-Dex group and 10.5 x 10(6)/kg in the control group. Thal-Dex may be considered an effective and relatively well-tolerated oral alternative to the more complex VAD regimen as front-line therapy for MM patients who are candidates for subsequent autologous transplantation.

Myeloma cell contamination of peripheral blood stem-cell grafts can predict the outcome in multiple myeloma patients after high-dose chemotherapy and autologous stem-cell transplantation

PURPOSE

High-dose chemotherapy with hematopoietic stem-cell rescue is increasingly being used in the treatment of multiple myeloma. Bone marrow and also peripheral blood stem-cell (PBSC) grafts contain measurable quantities of plasma cells, the biological significance of which is unknown.

METHODS

Patients with multiple myeloma were mobilized with chemotherapy and filgrastim. The number of CD38++/CD138+ cells/kg in the grafts for autologous transplantation was determined by flow cytometry. Patients were stratified into two groups (threshold 4.5 x 10(5) plasma cells kg(-1)) of reinfused plasma cells in the first autologous graft.

RESULTS

The median statistical progression-free survival was 14 months (4-34 months) in the high-contamination group (>4.5 x 10(5) plasma cells kg(-1)) compared to 26 months (4-43 months) in the low-contamination group (<4.5 x 10(5) plasma cells kg(-1), P =0.0096). Patients with 13q deletion were more frequently found to have a high contamination of the stem-cell graft with malignant plasma cells.

CONCLUSIONS

Patients with graft contamination of more than 4.5 x 10(5) plasma cells kg(-1) had a high risk of early disease progression after high-dose chemotherapy. In vivo tumor cell purging prior to mobilization chemotherapy might be one strategy to improve the time to progression of high-risk patients.

Extramedullary vs medullary relapse after autologous or allogeneic hematopoietic stem cell transplantation (HSCT) in multiple myeloma (MM) and its correlation to clinical outcome

Risk-adapted treatment of multiple myeloma (MM) includes autologous (auto-) and allogeneic (allo-) hematopoietic stem cell transplantation (HSCT). Case reports on extramedullary (EM) compared to bone marrow (BM) relapse after HSCT suggest a dismal prognosis. We compared the outcome of 78 MM patients relapsing after auto- (group A: n = 53) or allo- (group B: n = 25) HSCT, stratified into BM (64 patients) vs EM (14 patients) relapse. The relapse-specific groups were also compared with respect to risk factors, including age, beta2-microglobulin, pretreatment, cytogenetics and stage. EM relapse sites were lungs (5), soft tissue (4), pericardium (2), bone (1), skin (1) and CNS (1). As of May 2004, the overall (OS) and progression-free (PFS) survival after HSCT in patients relapsing from EM sites was not significantly different from BM relapse patients, both after auto- and allo-HSCT. Although MM patients relapsing from EM sites after allo-HSCT used to be regarded as having few therapeutic options, we observed encouraging responses to donor lymphocyte infusions (DLI). Treatment responses to DLIs were observed in 5/9 (56%) BM relapse patients, and in 3/4 (75%) EM relapse patients. These observations suggest that EM relapse after HSCT is common and needs an individualized diagnostic and therapeutic approach in MM during clinical follow-up after HSCT.

Post-transplantation tumour load in bone marrow, as assessed by quantitative ASO-PCR, is a prognostic parameter in multiple myeloma

High-dose therapy (HDT) and autologous transplantation prolongs remission duration and survival in multiple myeloma (MM), but relapse still occurs at a median of 2 years post-HDT. In order to investigate whether the number of residual tumour cells in the bone marrow (BM) after transplantation can predict the duration of response, a quantitative allele-specific oligonucleotide polymerase chain reaction (qASO-PCR) assay was used to measure tumour load in BM at 3-6 months post-HDT in 67 patients. The method of maximally selected log-rank statistics was used to test for the existence of a cut-off value in the BM tumour load data set. A cut-off value with respect to progression-free survival (PFS) was identified (P = 0.001). The estimated threshold for placing patients into a "good" or "bad" prognostic group was 0.015% (n = 22 and 38 respectively) with a median PFS of 64 months vs. 16. Multivariate analysis showed grouping by PCR result to be an independent prognostic factor for PFS (estimated hazard ratio after shrinkage, 3.91). This study identifies for the first time a threshold of the post-HDT tumour load with prognostic significance for PFS in MM. Quantitative molecular assessment thus may help to identify those patients who are in need of further treatment early after autologous transplantation.

Cellular immune responses in multiple myeloma patients with treatment-induced cytopenia early after high-dose chemotherapy and autologous peripheral blood stem cell transplantation

Proliferative T cell responses were compared for two patient groups with severe treatment-induced leukopenia (white blood cell counts < 0.5 x 10(9)/l): (i). multiple myeloma patients receiving high-dose melphalan and autologous peripheral blood stem cell transplantation; (ii). patients receiving conventional intensive chemotherapy for acute leukemia or myelodysplasia. Although the majority of circulating leukocytes were CD2(+)TCRalphabeta(+) in both groups, the myeloma patients showed significantly lower T cell proliferation in responses to several activation signals (anti-CD3, anti-CD3 + IL2, anti-CD3 + anti-CD28, anti-CD3 + anti-CD28+IL2. Our results suggest that myeloma patients with post-transplant cytopenia have a more severe cellular immune defect than patients with other hematological malignancies and severe cytopenia due to conventional intensive chemotherapy.

Hemopoietic Recovery and Infectious Complications in Breast Cancer and Multiple Myeloma after Autologous CD34+ Cell-Selected Peripheral Blood Progenitor Cell Transplantation

Autografting with CD34+ cell-selected peripheral blood progenitor cells (PBPC) is often associated with a prolonged recovery time and a higher incidence of infections. The aim of our study was to evaluate whether underlying disease influences hemopoietic recovery and the infectious complications occurring after transplantation. We studied 19 breast cancer (BC) patients and 17 multiple myeloma (MM) patients entered in a high-dose chemotherapy (HDC) program of tandem autografting with CD34+ cell-selected PBPC. PBPC were collected after mobilizing chemotherapy plus granulocyte colony-stimulating factor and were processed for selection of CD34+ cells. After selection, a median of 53% CD34+ cells was recovered with a median final purity of 92% with no significant differences between the MM (52% and 92%, respectively) and BC (53% and 89%, respectively) patients. Medians of 4.5 x 10(6)/kg CD34+ cells (BC, 4.4 x 10(6)/kg; MM, 5.4 x 10(6)/kg) and 18 x 10(4)/kg colony-forming units-granulocyte-macrophage (BC, 21 x 10(4)/kg: MM, 16 x 10(4)/kg) were reinfused after each HDC. Twenty-six patients (10 MM and 16 BC) underwent tandem autografting, and 10 patients received only 1 autograft because of inadequate collection (5 patients), clinical condition (3 patients), and refusal (2 patients). In the BC patients, the HDC regimen included a high-dose melphalan course followed by an ICE (ifosfamide, carboplatin, and etoposide) course. In the MM patients, the regimen consisted of a course of high-dose melphalan therapy and a course of ICBV (idarubicin, cyclophosphamide [Cytoxan], BCNU, and etoposide) or total body irradiation, etoposide, and Cytoxan. We found a significantly prolonged time for neutrophil recovery to > 500/microL in the MM patients (13 days versus 10 days; P < .002), whereas the times for platelet recovery to > 20,000/microL in the two groups were not different (13 days versus 12 days; not significant). No late engraftment failures and no toxic deaths were observed. The incidences of extrahematologic toxicity were similar for the two patient groups. All patients received similar anti-infection prophylaxis for 3 months after transplantation. After 12 months of observation, we found a statistically significant higher incidence of bacterial infections in MM patients in both the early (77.8% versus 48.6%; P < .034) and the late (41.1% versus 0%; P < .014) posttransplantation periods, whereas the incidences of fungal infections were similar in the two groups. Viral infections consisted of herpes zoster virus infection in 2 patients of each group, and cytomegalovirus infection was observed in 3 MM patients and no BC patients. Our experience demonstrates a prolonged neutrophil recovery time and higher incidences of bacterial and viral infections in MM patients compared with BC patients. These observations, although limited by the small sample size, suggest that the underlying disease may influence the incidence of infections after CD34- cell-selected transplantation and should be considered in the planning of appropriate antimicrobial prophylaxis in the autologous transplantation setting.

Functional and kinetic characterization of granulocyte colony-stimulating factor-primed CD34− human stem cells

We assessed the functional properties and the kinetic status in vitro, and the engraftment potential in vivo of human haematopoietic stem cells according to the expression of CD34 antigen. Lin-CD34- and Lin-CD34+ cells were isolated from granulocyte colony-stimulating factor-primed peripheral blood (PB) cells of healthy donors. The CD34- cell fraction did not contain either clonogenic cells in semisolid culture or long-term culture initiating cells (LTC-IC). However, stroma-dependent liquid cultures and cytokines induced CD34 expression on a minority of stem cells, acquisition of clonogenic capacity and generation of LTC-IC. Significantly higher percentages of quiescent G0 cells and lower percentages of cycling G1 cells were found in Lin-CD34- cells when compared with Lin-CD34+ cells. Kinetic quiescence of Lin-CD34- cells was associated with a significantly higher expression of the negative regulators of the cell cycle, p27Kip1 and p21(cip1/waf1). Cytokine-mediated induction of CD34, in vitro, resulted in cycling of stem cells and downregulation of p27. There was a higher rate of human long-term engraftment in immunocompromised non-obese diabetic (NOD)/recombination activating gene 1null and NOD/severe combined immunodeficient-beta2microglobulin(null) mice injected with CD34+ cells. Thus, our study indicated that CD34 expression on human PB stem cells was associated with haematopoietic activity, cell-cycle recruitment and downregulation of p27Kip1 in vitro and higher engraftment capacity in vivo.

Autologous transplantation of granulocyte colony-stimulating factor-primed bone marrow is effective in supporting myeloablative chemotherapy in patients with hematologic malignancies and poor peripheral blood stem cell mobilization

We assessed the hematopoietic recovery and transplantation-related mortality (TRM) of patients who had failed peripheral blood stem cell mobilization and subsequently received high-dose chemotherapy supported by granulocyte colony-stimulating factor (G-CSF)-primed bone marrow (BM). Studied were 86 heavily pretreated consecutive patients with acute leukemia (n = 21), refractory/relapsed non-Hodgkin lymphoma (n = 41) and Hodgkin disease (n = 17), and multiple myeloma (n = 7). There were 78 patients who showed insufficient mobilization of CD34+ cells (< 10 cells/microL), whereas 8 patients collected less than 1 x 106 CD34+ cells/kg. BM was primed in vivo for 3 days with 15 to 16 microg/kg of subcutaneous G-CSF. Median numbers of nucleated cells, colony-forming unit cells (CFU-Cs), and CD34+ cells per kilogram harvested were 3.5 x 10(8), 3.72 x 10(4), and 0.82 x 10(6), respectively. Following myeloablative chemotherapy, median times to achieve a granulocyte count higher than 0.5 x 10(9)/L and an unsupported platelet count higher than 20 and 50 x 10(9)/L were 13 (range, 8-24), 15 (range, 12-75), and 22 (range, 12-180) days, respectively, for lymphoma/myeloma patients and 23 (range, 13-53), 52 (range, 40-120), and 90 (range, 46-207) days, respectively, for leukemia patients. Median times to hospital discharge after transplantation were 17 (range, 12-40) and 27 (range, 14-39) days for lymphoma/myeloma and acute leukemia patients, respectively. TRM was 4.6%, whereas 15 patients died of disease. G-CSF-primed BM induces effective multilineage hematopoietic recovery after high-dose chemotherapy and can be safely used in patients with poor stem cell mobilization.

Autologous blood cell transplantation in multiple myeloma: impact of CD34+ cell selection with long follow-up

Positive CD34(+) selection to purge blood cell harvests is one way to attempt to reduce the high relapse risk after high-dose chemotherapy (HDT) supported by autologous blood cell transplantation (ABCT) in patients with multiple myeloma (MM). Until recently, however, the impact of CD34(+) selection, if any, on long-term clinical outcome in MM has remained obscure. We have analyzed engraftment kinetics, response to HDT, progression-free survival (PFS), and overall survival (OS) for 64 consecutive MM patients who have been treated with up-front HDT plus ABCT at our institution between 1993 and 1998. Nonrandomized comparisons were made between transplants with unselected (39 patients) and CD34(+)-selected (25 patients) grafts. The engraftment kinetics, need of blood product support, discharge time from hospital, and response to HDT were similar for both unselected and selected transplants. The median PFS was also similar (26 and 30 months, respectively) for the both groups. With a median follow-up time for the survivors of 67.5 months, the median OS (78 and 75 months, respectively) did not differ between transplants with unselected and selected grafts. In conclusion, this nonrandomized study suggests that positive CD34(+) selection has no beneficial impact on long-term outcome of patients with MM.

Tandem transplants with different high-dose regimens improve the complete remission rates in multiple myeloma. Results of a Grupo Español de Síndromes Linfoproliferativos/Trasplante Autólogo de Médula Osea phase II trial

Between 1994 and 1999, 88 multiple myeloma (MM) patients were included in a phase II study to evaluate a tandem autologous stem cell transplantation (ASCT) programme. The first was conditioned with melphalan 200 mg/m2 (MEL200-ASCT1), and the second with cyclophosphamide, etoposide and BCNU (CBV-ASCT2). All patients were in response after MEL200-ASCT1. A control group of MM patients with response to a single ASCT was selected to compare outcomes. After MEL200-ASCT1, 26 patients (30%) achieved complete remission (CR). Of the remaining 48 evaluable patients, 16 (33%) achieved CR with CBV-ASCT2. The final CR rate was 48%. The 5-year survival (OS) was 55%[95% confidence interval (CI) 43-67%] while the event-free survival (EFS) was 28% (95% CI 15-39%). CR status after CBV-ASCT2 was the most important prognostic factor for OS and EFS (P = 0.00001), although no differences in outcomes were detected when the patients in CR after MEL200-ASCT1 were compared with those who obtained CR after CBV-ASCT2. Univariate and multivariate analyses showed improved OS and EFS for the tandem series as compared with the control series treated with a single MEL200-ASCT. However, in a stratified comparison by response, there were no prognostic differences between tandem patients and control patients treated with a single ASCT. In summary, our study suggests that the benefit of a second high-dose therapy course depends on its capacity to result in CR for MM patients who have not attained CR after ASCT1.

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the therapy of multiple myeloma: an evidence-based review

Evidence supporting the role of hematopoietic stem cell transplantation (SCT) in the therapy of multiple myeloma (MM) is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published medical literature and for grading the quality of the evidence, the strength of the evidence, and the strength of the treatment recommendations. Treatment recommendations based on the evidence presented in the review were made unanimously by a panel of MM experts. Recommendations for SCT as an effective therapy for MM include the following: SCT is preferred to standard chemotherapy as de novo therapy; SCT is preferred as de novo rather than salvage therapy; autologous peripheral blood stem cell transplantation (PBSCT) is preferred to bone marrow transplantation (BMT); and melphalan is preferred to melphalan plus total body irradiation as the conditioning regimen for autologous SCT. Recommendations that SCT is not effective include the following: current purging techniques of bone marrow. Recommendations of equivalence include the following: PBSCT using CD34+ selected or unselected stem cells. No recommendation is made for indications or transplantation techniques that have not been adequately studied, including the following: SCT versus standard chemotherapy as salvage therapy, tandem autologous SCT, autologous or allogeneic SCT as a high-dose sequential regimen, allogeneic BMT versus PBSCT, a preferred allogeneic myeloablative or non-myeloablative conditioning regimen, and maintenance therapy post-autologous SCT with interferon alpha post-SCT. The priority area of needed future research is maintenance therapy posttransplantation with nothing versus interferon alpha versus other agents such as corticosteroids or thalidomide or its derivatives.

Collection of peripheral blood stem cells in newly diagnosed myeloma patients without any prior cytoreductive therapy: the first step towards an 'operational cure'?

We have shown that primary therapy with non-myeloablative (140 mg/m(2)) high-dose melphalan (HDM) without hematopoietic support results in high response rates in untreated myeloma and very long-term survival of some patients. This study was designed to see if sufficient CD34 (+) cells can be harvested at presentation in newly diagnosed patients to administer myeloablative HDM (200 mg/m(2); HDM200) with autograft as primary therapy. This may improve outcome by rapid achievement of complete remission (CR) and possible avoidance of late myelodysplasia as a consequence of non-transplant induction chemotherapy. Thirty untreated patients received 1 g/m(2) methylprednisolone daily (days 1-6) and 12-16 micro g/kg G-CSF daily (days 3-6), and underwent leukapheresis on days 6 and 7. The median CD34(+) cell yield was 1.31 x10(6)/kg (range, 0.23-5.63), and was > or =1 x10(6)/kg in 73%. Cell yields were significantly lower than in 82 historical controls apheresed after completion of induction chemotherapy (median 2.16 x 10(6)/kg), and improved in patients who were apheresed again after induction chemotherapy. Three patients received primary therapy with HDM200 and autograft using these cells and attained CR. We conclude that it is possible to harvest stem cells in three-quarters of untreated myeloma patients. Increasing the number of apheresis procedures is needed to improve the number of CD34(+) cells collected.

Functional analysis of human hematopoietic repopulating cells mobilized with granulocyte colony-stimulating factor alone versus granulocyte colony-stimulating factor in combination with stem cell factor

Using in vitro progenitor assays, serum-free in vitro cultures, and the nonobese diabetic/severe combined immune-deficient (NOD/SCID) ecotropic murine virus knockout xenotransplantation model to detect human SCID repopulating cells (SRCs) with multilineage reconstituting function, we have characterized and compared purified subpopulations harvested from the peripheral blood (PB) of patients receiving granulocyte colony-stimulating factor (G-CSF) alone or in combination with stem cell factor (SCF). Mobilized G-CSF plus SCF PB showed a 2-fold increase in total mononuclear cell content and a 5-fold increase in CD34-expressing cells depleted for lineage-marker expression (CD34(+)Lin(-)) as compared with patients treated with G-CSF alone. Functionally, G-CSF plus SCF-mobilized CD34(+)CD38(-)Lin(-) cells contained a 2-fold enhancement in progenitor frequency as compared with G-CSF-mobilized subsets. Despite enhanced cellularity and progenitor capacity, G-CSF plus SCF mobilization did not increase the frequency of SRCs as determined by limiting dilution analysis by means of unfractionated PB cells. Purification of SRCs from these sources demonstrated that as few as 1000 CD34(+)CD38(-)Lin(-) cells from G-CSF-mobilized PB contained SRC capacity while G-CSF plus SCF-mobilized CD34(+)CD38(-)Lin(-) cells failed to repopulate at doses up to 500 000 cells. In addition, primitive CD34(-)CD38(-)AC133(+)Lin(-) cells derived from G-CSF plus SCF-mobilized PB were capable of differentiation into CD34-expressing cells, while the identical subfractions from G-CSF PB were unable to produce CD34(+) cells in serum-free cultures. Our study defines qualitative and quantitative distinctions among subsets of primitive cells mobilized by means of G-CSF plus SCF versus G-CSF alone, and therefore has implications for the utility of purified repopulating cells from these sources.

Qualitative and quantitative polymerase chain reaction detection of the residual myeloma cell contamination after positive selection of CD34+ cells with small- and large-scale Miltenyi cell sorting system

The purging efficacy of the Miltenyi sorting system was evaluated by qualitative and TaqMan quantitative polymerase chain reaction (PCR) in myeloma patients, using immunoglobulin genes. After small-scale selection, qualitative PCR showed that in 6 of 12 leukaphereses myeloma cells were no longer detectable. Envisaging a possible clinical application, the leukaphereses from three patients underwent large-scale selection. Qualitative PCR showed that myeloma cells were still detectable. Quantitative PCR, performed in two patients, showed a tumour depletion of 1 and 2 logs respectively. Although numbers are small, the promising results obtained with small-scale selection were not reproduced in large-scale experiments.

Real-time polymerase chain reaction in multiple myeloma: quantitative analysis of tumor contamination of stem cell harvests

OBJECTIVE

Autologous transplantation of bone marrow (BM) and peripheral blood progenitor cells (PBPC) is commonly used for treatment of multiple myeloma (MM). Although both stem cell sources harbor residual clonal cells, a quantitative evaluation of their level of tumor contamination (LTC) still needs to be performed through highly accurate and reproducible approaches. In this study, we used a validated real-time polymerase chain reaction (PCR) strategy to evaluate LTC of BM and PBPC samples obtained from MM patients.

MATERIALS AND METHODS

The patients underwent two different mobilization courses (defined as early or late course) following two cycles of cyclophosphamide 5 g/m(2). LTC was evaluated by measuring the number of clonal immunoglobulin heavy-chain rearrangements followed by normalization of samples using the GAPDH gene.

RESULTS

Overall, 26 PBPC and 12 BM samples were analyzed. Main results are as follows. 1) PBPC harvests are less contaminated than BM samples taken immediately after each mobilization course (median difference 2.68 logs; range 1.7 to 4.6) (p < 0.0001). 2) LTC of PBPC harvests has only minimal variation among different leukaphereses performed during the same mobilization course (median difference 0.45 logs; range 0.22 to 1.2). 3) No difference was observed among PBPC and BM samples obtained after the late mobilization course as compared to the early mobilization course (median reduction 0.21 logs; range -0.39 to 1.3) (p = 0.84). 4) In PBPC but not in BM samples, there is a clear overestimation of the percentage of plasma cells when flow cytometric evaluation of CD38(bright) cells is compared to real-time PCR results. This suggests that in PBPC, most CD38(bright) cells do not belong to the neoplastic clone.

CONCLUSIONS

Real-time PCR using the IgH rearrangement proved an effective tool for monitoring LTC in stem cell harvests from MM patients. The smaller LTC of PBPC harvests supports the role of PBPC as stem cell rescue for MM patients compared to BM cells.

Myeloablative treatments for multiple myeloma: update of a comparative study of different regimens used in patients from the Spanish registry for transplantation in multiple myeloma

After a previous analysis that did not detect clear differences in the results of three conditioning regimens used for autologous stem cell transplantation (ASCT) in patients from the Spanish Registry for Transplant in Multiple Myeloma (MM), we have updated the registry, including a larger number of cases and a fourth conditioning regimen with a longer follow-up. We evaluate 472 MM patients treated with 200 mg/m2 melphalan (MEL200), 135 patients treated with 140 mg/m2 melphalan plus total body irradiation [(MEL140 + TBI)], 186 patients treated with 12 mg/kg busulphan plus 140 mg/m2 melphalan (BUMEL) and 28 patients treated with 14 mg/kg busulphan followed by cyclophosphamide 120 mg/kg (BUCY). There were no significant differences in respect to either transplant related death or haematological recovery, regardless of growth factor use, between the four conditioning programs. Nevertheless, hospitalization time with MEL200 was less than with BUMEL when growth factors were used (19+/-9 vs. 25+/-9 days, P = 0.009) and less than with MEL140 + TBI without growth factors (20+/-8 days vs. 27+/-9 days, P = 0.002). In patients with measurable disease at ASCT (non-complete remission [CR]), BUMEL achieved a 51% CR vs. 43%-31% in the other groups (P = 0.007). The response rate for patients in partial remission (PR) at ASCT was 100% with BUMEL vs. 93%-86% in the other groups (P between 0.02 and 0.0007). The median overall survival (OS) for the BUMEL group was 57 months (95% confidence interval [CI]: 51-78) as compared to 45 (CI: 36-64) months for the MEL200 group and 39 (CI: 28-72) months for the MEL140 + TBI and BUCY groups. The median event free survival (EFS) was longer in the BUMEL group [30 (CI: 22-44) mo] than in the MEL200 [22 (CI: 18-26) mo], BUCY [23 (CI: 11-50) mo] or MEL140 + TBI groups [20 (CI: 15-29) mo]. Nevertheless, the differences in OS and EFS did not reach statistical significance in either the univariate analysis or the multivariate analysis adjusted with other high prognostic weight factors. As in the initial study, differences in regards to the anti-myeloma effect of the conditioning regimens are not conclusive. However, the better response rates associated with the favorable tendency in outcome achieved with BUMEL, continue to justify further prospective studies.

Negative selection of peripheral blood stem cells to support a tandem autologous transplantation programme in multiple myeloma

We recently described a two-step negative selection procedure whereby peripheral blood stem cells (PBSCs) were efficiently purged of contaminating neoplastic cells by a combination of monoclonal antibodies. Here, we report 60 newly diagnosed multiple myeloma (MM) patients treated with a double transplant programme and randomized to receive either unmanipulated or in vitro purged PBSCs. We demonstrated that this technique is feasible and safe without significant loss of either CD34+ or CD3+ cells. Haematological engraftment and immunological reconstitution were rapid without treatment-related mortality. Using polymerase chain reaction (PCR), we compared the level of minimal residual disease (MRD) in PBSC before and after in vitro purging and in vivo after transplant. A median of one tumour cell per 10(2) normal cells (range 10(1)-10(5)) was seen in the unmanipulated aphereses with a 3-4 log reduction after manipulation in vitro. However, despite this tumour debulking, all patients remained PCR positive in vivo. At 3 years, the estimated event-free survival was 40% in the control arm and 72% in the experimental arm (P = 0.05), whereas the estimated overall survival was 83% in both arms. This suggests that autologous transplantation using efficiently purged PBSCs can be performed safely, but confirms the need for innovative protocols for MRD eradication in vivo.

Predicting long-term (> or = 5 years) event-free survival in multiple myeloma patients following planned tandem autotransplants

Although outcome in multiple myeloma (MM) patients has improved significantly with the introduction of autotransplants (AT), the curability of this approach remained to be demonstrated. Therefore, we analysed outcome and prognostic factors using a logistic regression model in 515 consecutive newly diagnosed and previously treated patients intended to receive melphalan-based tandem transplants with follow up of > or = 5 years. One quarter of patients had event-free survivals (EFS) > or = 5 years with no further relapses seen after 7 years (46 patients on plateau). On multivariate analysis, factors associated with EFS > or = 5 years were absence of chromosome 11 and 13 abnormalities (odds ratio: 6.1), < or = 12 months of preceding standard-dose therapy (SDT) (OR: 2.6) and beta-2 microglobulin (B2M) level < or = 2.5 mg/l at time of first AT (OR: 1.7). Patients with only favourable variables (25%) had a 7-year EFS in excess of 35%, compared with 15% and 10%, respectively, with one (43%) or two unfavourable variables (27%), and 0% for 5% of patients with three unfavourable variables (P < 0.0001). Using a 1-year landmark analysis to allow for guaranteed time and thereby excluding early treatment failures, attaining a complete remission (CR) had no significant effect on long-term survival. Our data are consistent with cure in MM patients with a CR duration . or = 7 years and re-establishment of a monoclonal gammopathy of undetermined significance (MGUS) phase in those with persistent evidence of disease post transplantation, but without disease progression > or = 7 years.

DCEP (dexamethasone, cyclophosphamide, etoposide, and cisplatin) is an effective regimen for peripheral blood stem cell collection in multiple myeloma

DCEP (dexamethasone, cyclophosphamide, etoposide, and cisplatin) has proved to be an effective salvage therapy for refractory-relapsed MM patients. Little is known, however, about its potential as mobilizing therapy. The aim of this study was to evaluate the efficacy of DCEP in mobilizing PBSC and to define its toxicity. Fifty-five MM patients received DCEP followed by G-CSF as part of high-dose programs including autologous transplantation. At the time of mobilization, 40 patients had previously received VAD only, and 15 alkylating agents. Mobilization was successful (minimum number of CD34(+) cells 2 x 10(6)/kg) in 48/55 patients (87%), and 41/55 patients (75%) collected >4 x 10(6)/kg CD34(+) cells. Of the seven patients who did not mobilize stem cells, five (71%) had been previously exposed to alkylating agents. The median number of CD34(+) cells harvested was 5.8 x 10(6)/kg (range 2.1-22.4). There was no treatment-related mortality. The side-effects of DCEP were always tolerable. No neutropenia <1000/microl nor thrombocytopenia <50,000/microl were observed. No patient required transfusion as a consequence of therapy, or hospitalization for septic complications. In conclusion, DCEP, in addition to its demonstrated anti-tumor activity, is an effective regimen for mobilizing peripheral blood progenitor cells in myeloma patients, with little or no side-effects. These properties render DCEP a useful regimen for the debulking and mobilization phase of high-dose programs for multiple myeloma.

Assessment of rapid remobilization intervals with G-CSF and SCF in murine and rhesus macaque models

BACKGROUND

Defining the optimum regimen and time for repeat peripheral blood progenitor cell mobilization would have important clinical applications.

STUDY DESIGN AND METHODS

Remobilization with SCF and G-CSF at 2 weeks after an initial mobilization in mice and at 2 or 4 weeks after an initial mobilization in nonhuman primates was examined. In mice, competitive repopulation assays were used to measure long-term progenitor cell-repopulating activity. In monkeys, mobilization of hematopoietic progenitor CFUs was used as a surrogate marker for progenitor cell-repopulating ability.

RESULTS

Efficacy of progenitor cell remobilization differed in the two animal species. In mice, peripheral blood progenitor cell-repopulating ability with repeat mobilization at 2 weeks was 70 percent of that with the initial mobilization. In monkeys, there was no significant difference in peripheral blood progenitor cell mobilization between the initial and the repeat mobilizations at 2 weeks. In mobilizations separated by 4 weeks, however, peripheral blood progenitor cell mobilization was higher than that with initial mobilizations.

CONCLUSION

In animal models, mobilization of peripheral blood progenitor cells with remobilization after a 2-week interval is similar to or moderately decreased from that with the initial mobilization. Progenitor cell collection at this time point may be useful in certain clinical circumstances. A 4-week interval between remobilizations may be preferable. Clinical trials in humans would be useful to clarify these issues.

Controversy in multiple myeloma transplants: tandem autotransplants and mini-allografts

Autologous stem cell transplantation appears to enhance outcome in multiple myeloma patients. To improve upon these results, various groups have utilized tandem autografts, as well as used reduced-conditioning allogeneic stem cell transplantation. These two approaches, discussed herein, have been promising. Inherent patient selection, however, appears to play a role and much of the data have not yet been subjected to peer-review scrutiny. At present, these strategies remain investigational and cannot be considered the standard-of-care for multiple myeloma patients.

Results of high-dose treatment with autologous stem cell support in patients with multiple myeloma

The introduction of high-dose treatment (HDT) with autologous hematopoietic stem cell support in patients with multiple myeloma (MM), although curative in only a minority of patients, has led to significantly longer event-free (EFS) and overall survival (OS) and likely improved quality of life compared with conventional chemotherapy. However, several issues remain unsettled. We review the current knowledge with respect to transplantation-related controversies, such as intensity of cytoreductive therapy (single v tandem transplants), optimal timing of the procedure, and potential benefit of graft purging and posttransplant consolidation chemotherapy. Special emphasis is placed on the safety and efficacy of transplant in elderly patients and in those with impaired renal function, who are usually excluded from the most effective therapy.