Human mesenchymal stem cell transplantation extends survival, improves motor performance and decreases neuroinflammation in mouse model of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a lethal disease affecting motoneurons. In familial ALS, patients bear mutations in the superoxide dismutase gene (SOD1). We transplanted human bone marrow mesenchymal stem cells (hMSCs) into the lumbar spinal cord of asymptomatic SOD1(G93A) mice, an experimental model of ALS. hMSCs were found in the spinal cord 10 weeks after, sometimes close to motoneurons and were rarely GFAP- or MAP2-positive. In females, where progression is slower than in males, astrogliosis and microglial activation were reduced and motoneuron counts with the optical fractionator were higher following transplantation. Motor tests (Rotarod, Paw Grip Endurance, neurological examination) were significantly improved in transplanted males. Therefore hMSCs are a good candidate for ALS cell therapy: they can survive and migrate after transplantation in the lumbar spinal cord, where they prevent astrogliosis and microglial activation and delay ALS-related decrease in the number of motoneurons, thus resulting in amelioration of the motor performance.

Poor prognosis osteosarcoma: new therapeutic approach.

Over the past 30 years, a significant improvement in the prognosis of localized osteosarcoma of the extremities has been observed. Despite these results, approximately 30-40% of patients will relapse, mostly within the first 3 years from diagnosis. The prognosis of patients with recurrent disease or metastases at diagnosis is poor. To improve the survival in this patient population, several attempts have been made. An increased dose intensity of chemotherapy induces short lasting remission but does not increase the survival. In the era of targeted therapy, few drugs have been tested with dismal results. The use of biological agents endowed with immunomodulant activity (that is IL-2) or reduced-intensity allogeneic hemopoietic SCT has produced intriguing results that need further confirmation. In this context, an ongoing study explores the antitumor activity of specific T-cytotoxic lymphocytes.

Lymphocyte subsets recovery following allogeneic bone marrow transplantation (BMT): CD4+ cell count and transplant-related mortality.

To assess the kinetics of lymphocyte subset recovery, 758 allografted patients were monitored by surface markers (CD3, CD4, CD8, CD56), with a 5-year follow-up. The donor was a matched sibling donor (MSD) (n=502) or an alternative donor (family mismatched or unrelated, AD) (n=256). The stem cell source was bone marrow for all patients. CD4+ cell recovery was influenced -- in univariate analysis -- by three factors: donor type, patient age and GvHD. This was not the case for CD8+ and CD56+ cells. The median CD4+ cell count on day +35 after HSCT was 86/mul. Patients achieving this CD4+ cell count had significantly lower transplant-related mortality (TRM) compared to patients who did not achieve this CD4+ cell count (20 vs 39%, P=0.00001), due to a lower risk of lethal infections (24 vs 47%, P=0.0003). In multivariate analysis MSD (RR 3.45, P=0.0001) and recipient age less than 16 years (RR 3.23, P=0.003) were significantly associated with a better CD4+ cell recovery. CD4+ counts on day +35 was predicted TRM (RR=1.97, P=0.0017) together with acute GvHD grade II-IV (RR 1.59, P=0.0097). No difference of TRM was observed for CD8+ and CD56+ cell counts.

Response to melphalan in up-front investigational window therapy for patients with metastatic Ewing's family tumours.

The aim of the study was to determine the activity and toxicity of melphalan as a single agent given in up-front therapy for patients with newly-diagnosed Ewing's family tumours with bone/bone marrow metastases. Nineteen patients were enrolled from 2001 to 2004. The treatment consisted of up-front therapy with melphalan (two courses of 50 mg/m2, 3 weeks apart). The overall rate of response to melphalan (complete response+partial response, according to the RECIST criteria) was 78%. Transient grade 3-4 neutropenia, thrombocytopenia and anaemia were recorded in 97%, 81% and 28% of melphalan courses, respectively. No other relevant toxicities were recorded. Melphalan proved to be active in up-front treatment at non-myeloablative doses, and its toxicity was predictable and manageable. The schedule adopted did not interfere with any further intensive chemotherapy or myeloablative treatment in the majority of cases.

Osteosarcoma cell line growth inhibition by zoledronate-stimulated effector cells.

Bisphosphonates have a profound effect on bone resorption and are widely used in the treatment of osteoclast-mediated bone diseases. Zoledronic acid (ZA), a third-generation biphosphonate, has a potent antitumor activity and expands gammadelta (gammadelta) T cells endowed of major histocompatibility complex-unrestricted lytic activity. Many solid tumors express tumor-specific antigens on their surface, representing targets for immune effector T cells. Nevertheless, the immune surveillance against clinically manifested tumors is relatively inefficient. Therefore, we investigated the hitherto unknown effects of ZA activated gammadelta T cells of normal donors on osteosarcoma cell lines. gammadelta T cells were stimulated with ZA and low doses of interleukin-2, and then analyzed for proliferation and generation of effector activity against osteosarcoma cell lines. Our results show the potent anti-tumor activity of ZA-stimulated gammadelta T cells and the enhanced immunosensitivity of osteosarcoma cell lines to gammadelta T cells suggesting that osteosarcoma is another gammadelta T cell susceptible tumor type.

Prospective comparative study of bone marrow transplantation and postremission chemotherapy for childhood acute myelogenous leukemia. The Associazione Italiana Ematologia ed Oncologia Pediatrica Cooperative Group.

PURPOSE: This study was conducted to assess the comparative values of allogeneic bone marrow transplantation (BMT) and autologous bone marrow transplantation (ABMT) with sequential postremission chemotherapy (SPC) in children with acute myelogenous leukemia (AML) in first remission. PATIENTS AND METHODS: From March 1987 to March 1990, 161 assessable patients younger than 15 years of age with newly diagnosed AML were treated uniformly with two courses of daunorubicin and standard-dose cytarabine. After initial consolidation with a course of daunorubicin, cytarabine, and thioguanine (DAT), patients in complete remission (CR) were randomized to receive either ABMT or SPC, except for those with an HLA-matched sibling who were assigned to undergo BMT. SPC consisted of three additional courses of DAT, followed by three pairs of drugs administered sequentially for a total of six cycles. RESULTS: Overall, 127 of 161 patients attained CR (79%). The estimated probabilities of survival and event-free survival (EFS) at 5 years for all patients were 42% and 25%, respectively (median follow-up, 28 months). For the 127 complete responders, the 5-year probability of disease-free survival (DFS) was 31%, with a cumulative risk of relapse of 64%. For the purpose of this study, all complete responders were evaluated for analysis of disease outcome according to the intent-to-treat principle, regardless of whether they actually received the intended therapy. The 5-year DFS was 51% for the BMT group (n = 24), significantly higher (P = .03) than that observed for the other cohorts: 21% for ABMT (n = 35), 27% for SPC (n = 37), and 34% for a group of 31 nonrandomized (NR) patients. Bone marrow relapse was the most frequent cause of postremission failure in all therapeutic subgroups, including the BMT cohort, in which no deaths attributable to the toxicity of the procedure were recorded. CONCLUSION: The results of this study show that BMT is more effective than ABMT or SPC in preventing leukemia relapse and extending DFS duration in children with AML in first remission.

Tumor response and toxicity after single high-dose versus standard five-day divided-dose dactinomycin in childhood rhabdomyosarcoma.

This report deals with a randomized prospective multicentric clinical trial in childhood rhabdomyosarcoma (RMS) conducted to evaluate the toxicity and the effectiveness of dactinomycin (ACT-D) administered as high, single doses v five-day, divided doses administered in combination with vincristine (VCR) and cyclophosphamide (CYC). Fifty-five group III evaluable patients (pts) less than 15 years of age with tumor size greater than 5 cm in diameter, without high-risk features of CNS involvement, and 15 group IV RMS pts were randomized to receive VAC as primary chemotherapy (CT): VCR, 1.5 mg/m2 intravenously (IV) days 1 and 8; CYC, 275 mg/m2 IV days 1 through 5; and ACT-D, 0.45 mg/m2 IV days 1 through 5 every 28 days for three cycles (33 pts), or VAC-M: CYC, 150 mg/m2 intramuscularly (IM) days 1 through 7; VCR, 2.0 mg/m2 IV day 8; and ACT-D, 1.7 mg/m2 IV day 8 every 21 days for four cycles (37 pts). Major responses (complete plus partial responses [PR]) were obtained in 67% of the VAC pts and in 70% of the VAC-M pts. Toxic effects were low, and no increased toxicity was observed in pts treated with high, single-dose ACT-D. These results confirm the effectiveness and feasibility of single, high doses of ACT-D with the advantage of requiring less pt hospitalization.

Treatment of acute myelogenous leukemia in children: results of the Italian Cooperative Study AIEOP/LAM 8204.

One hundred thirty-three children with acute myelogenous leukemia (AML) entered the multicenter Pediatric Branch of the Italian Association Against Leukemia trial AIEOP/LAM 8204 between July 1982 and May 1986. Induction therapy consisted of two courses of daunomycin (DNM) plus cytosine arabinoside (Ara-C). Those patients who achieved remission were given four courses of consolidation with DNM, 6-thioguanine (6-TG) and escalated doses of Ara-C followed by six courses of sequential continuation therapy using monthly pairs: etoposide (VP-16)/Ara-C, Ara-C/6-TG, and DNM/Ara-C. Periodic intrathecal Ara-C was used for CNS prophylaxis. One hundred seven (80%) children achieved complete remission (CR). Kaplan-Meier estimates of 3-year disease-free survival (DFS) and event-free survival (EFS) are 41% and 33%, respectively. Relapses occurred in 34 patients after 5 to 97 weeks (32 marrow; 2 marrow plus CNS). Overall, 14 patients died of complications during treatment (nine during induction; five during the postremission phase), mostly from infection. Risk factor analysis showed that induction failures occurred predominantly in children with French-American-British (FAB) M5 and in those with elevated leukocyte counts; by step-up Cox analysis, only FAB subtype was predictive of remission success. None of the variables examined was significant for predicting the duration of remission. Hyperleukocytosis was predictive of a significantly worse EFS rate. These results are encouraging and further support the use of intensive chemotherapy programs for childhood AML.

High-dose chemotherapy in the treatment of relapsed osteosarcoma: an Italian sarcoma group study.

PURPOSE: To study the feasibility and activity of two courses of high-dose chemotherapy (HDCT) in patients with osteosarcoma in metastatic relapse. PATIENTS AND METHODS: Patients with high-grade osteosarcoma in metastatic relapse (multiple metastases or solitary metastasis at intervals of less than 30 months) were eligible for study. High-dose chemotherapy consisted of carboplatin and etoposide followed by stem-cell rescue. A second course was planned 4 to 6 weeks after the first. Surgery was performed before or after HDCT. RESULTS: Thirty-two patients were enrolled onto the study. At the end of the treatment, 25 patients were in complete remission (CR), six were alive with disease progression, and one died of toxicity. At present, 14 patients are alive with a median survival time of 23 months from study entry: four are in first CR, three are in second CR, and one is in fourth CR. Six patients are alive with disease. Eighteen patients (56%) died: 17 of disease and one of toxicity. Transplantation-related mortality was 3.1%. The relapse or progression disease rate was 84.4%. The 3-year overall survival rate is 20% and the 3-year disease-free survival rate is 12%. CONCLUSION: HDCT combined with surgery is feasible and can induce CR in a large portion of patients. Two points, however, need to be considered: only patients who are chemosensitive to induction treatment can obtain CR after HDCT, and the length of remission is short, because most patients relapse. Thus novel strategies are needed to maintain the remission status or to treat patients who do not respond to induction treatment.

Clinical relevance of DNA ploidy and proliferative activity in childhood rhabdomyosarcoma: a retrospective analysis of patients enrolled onto the Italian Cooperative Rhabdomyosarcoma Study RMS88.

PURPOSE: Evaluation of the possible clinical relevance of DNA ploidy and proliferative activity assessed as S-phase fraction (SPF) in childhood rhabdomyosarcoma (RMS). PATIENTS AND METHODS: We conducted a retrospective study on 59 RMS patients enrolled onto the ICS-RMS88 protocol (seven botryoid, 35 embryonal, and 17 alveolar RMS), for which formalin-fixed paraffin-embedded (FFPE) tissue was available. Nuclear suspensions for cytometric investigation were obtained using a mechanical disaggregation. Tumors were distinguished according to their DNA index (DI) value as follows: diploid (0.9 < DI < 1.1), hyperdiploid (1.1 < or = DI < 1.8 or DI > or = 2.2), and tetraploid (1.8 < or = DI < 2.2); for analysis of SPF, a cutoff value of 14% was used. RESULTS: DNA histograms were diploid in 19 (33%) cases, hyperdiploid in 29 (49%), and tetraploid in 10 (32%). One patient showed both a hyperdiploid and a tetraploid peak. The 5-year overall survival (OS) rate by ploidy status was 73% in hyperdiploid patients as compared with 33% and 25% in diploid and tetraploid patients, respectively (P = .0012). A striking difference emerged when the 5-year OS for the combined diploid and tetraploid RMS groups was compared with survival of the hyperdiploid RMS group: 30% versus 73%, respectively (P = .0006). In addition, the SPF was prognostically relevant: 5-year OS by SPF less than or greater than 14% was 70% and 36%, respectively (P = .009). Multivariate analysis confirmed the importance of DNA content (P = .0006) and SPF (P = .034) in predicting survival. CONCLUSION: These findings confirm that ploidy and SPF are important new prognostic factors that are able to identify selected groups of patients at high risk of treatment failure, even if the tumor's presentation is favorable according to standard criteria.

The common TEL/AML1 rearrangement does not represent a frequent event in acute lymphoblastic leukaemia occuring in children with Down syndrome.

Individuals with constitutional trisomy 21 (Down syndrome) are at increased risk of developing acute leukaemias, both of myeloid and lymphoid lineage. Although the cause of leukaemia in Down syndrome (DS) remains unknown, potential candidate genes include the ones on chromosome 21, and in particular AML1, the rearrangement of which in the t(8,21) is associated with the French-American-British (FAB) classification M2 subtype of acute myeloid leukaemia (AML) in the general population and has been described in Down patients with AML-M2. Recently, a new rearrangement involving AML1, the t(12;21), producing the TEL/AML1 hybrid transcript, has been described by molecular analysis as the most recurrent genetic lesion in childhood acute lymphoblastic leukemia (ALL). In order to investigate whether the t(12;21) could give a molecular clue as to the precise basis of the etiologic association between DS and acute lymphoblastic leukemia, we tested a series of 11 consecutive cases of ALL in DS children for the presence of the TEL/AML1 transcript, by RT-PCR analysis. We report absence of the TEL/AML1 rearrangement among the 11 cases tested. This data may be suggestive of alternative pathways involved in the pathogenesis of ALL in children with constitutional trisomy 21.

Long-term results of the Italian Association of Pediatric Hematology and Oncology (AIEOP) acute lymphoblastic leukemia studies, 1982-1995.

The first multicentric approach to childhood acute lymphoblastic leukemia (ALL) treatment in Italy started in the early 1970s when the Associazione Italiana di Ematologia ed Oncologia Pediatrica (AIEOP) was founded. Since then the AIEOP has conducted nationwide chemotherapy protocols. Results obtained in three different periods (1982-1986, 1987-1990, 1991-1995) are reported here. Treatment schedules have been characterized by a progressive intensification of systemic therapy and by a progressive substitution of protracted intrathecal therapy for cranial irradiation as central nervous system (CNS) preventive therapy. In the third period cranial radiotherapy (CRT) has been administered only to patients at high risk of relapse or with CNS involvement at diagnosis (about 15% of the overall population). A progressive improvement of therapeutic results, with a steady reduction of isolated CNS relapse rates have been obtained in the three periods considered here. The AIEOP experience shows that CRT can be safely omitted in non-high risk patients, unless they are T-ALL patients with WBC count at the diagnosis > or =100,000/mm3, and that intensification of treatment allows the improvement of overall results with a reduction of the impact of NCI prognostic criteria. Over the years, AIEOP has also continued to foster active cooperation at an international level. In the ongoing AIEOP ALL 2000 study, conducted in cooperation with the BFM group, patients are stratified according to the presence of translocations t(9;22) and t(4;11) and to treatment response (either initial steroid therapy or induction) or minimal residual disease). This cooperation will allow an adequate recruitment of patients to answer relevant randomized questions in the context of a study in which patients are stratified according to minimal residual disease findings.

Stem cell factor suppresses apoptosis in neuroblastoma cell lines.

Stem cell factor (SCF) is a glycoprotein growth factor produced by marrow stromal cells that acts after binding to its specific surface receptor, which is the protein encoded by the protooncogene c-kit. SCF synergizes with specific lineage factors in promoting the proliferation of primitive hematopoietic progenitors, and has been administered to expand the pool of these progenitors in cancer patients treated with high-dose chemotherapy. SCF and its c-kit receptor are expressed by some tumor cells, including myeloid leukemia, breast carcinoma, small cell lung carcinoma, melanoma, gynecological tumors, and testicular germ cell tumors. Previous studies of SCF in neuroblastoma have produced conflicting conclusions. To explore the role of SCF in neuroblastoma, we studied five neuroblastoma lines (IMR-5, SK-N-SH, SK-N-BE, AF8, and SJ-N-KP) and the neuroepithelioma line CHP-100. All lines expressed mRNA for c-kit and c-kit protein at low intensity as measured by flow cytometry, and secreted SCF in medium culture as shown by ELISA. Exogenous SCF did not modify 3H thymidine uptake in the neuroblastoma and neuroepithelioma cell lines. After 6 days' culture in the presence of anti-c-kit, the number of viable neuroblastoma cells was significantly lower than the control, and terminal deoxynucleotidyl transferase assay showed a substantial increase of apoptotic cells: The percentage of positive cells was 1-3% in the control lines, whereas in the presence of anti c-kit it varied from 29% of SK-N-BE to 92% of CHP-100. After 9 days' culture in the presence of anti-c-kit, no viable cells were detectable. These data indicate that SCF is produced by some neuroblastoma cell lines via an autocrine loop to protect them from apoptosis.

Population-based survival after childhood lymphoblastic leukaemia in time periods corresponding to specific clinical trials from 1979 to 1998--a report from the Childhood Cancer Registry of Piedmont (Italy).

This study evaluated the outcome after childhood acute lymphoblastic leukaemia (ALL) in a population aged 0-14 years served by the Childhood Cancer Registry of Piedmont (CCRP) during the accrual periods to nationwide clinical studies run by the Italian Association for Paediatric Haematology and Oncology (AIEOP). In the time period considered (March 1979-December 1998) the CCRP recorded 498 incident cases of ALL. The living status on 31 December 2000 was known for 497 cases. Overall survival at 5 years was 74.1% standard error (S.E.) 2.0%). It increased from 58.6% (S.E. 4.9%) for cases diagnosed in March 1979-July 1982 to 87.3 (S.E. 3.6) in May 1995-December 1998. Results observed from data in our population-based study in Piedmont were similar to those presented in the nationwide clinical trials. Survival was better (statistically significant) for children aged 1-4 years, with a white blood cell (WBC) count lower than 10 000 x 10(3) cells/litre and for B-precursor ALL. Differences by immunophenotype were statistically significant only in the univariate analyses. Girls showed a non-statistically significant survival advantage over boys. Results of the present study show the impact on the population of recent clinical trials and emphasise the role of population-based cancer registries in evaluating childhood cancer care delivery in a given population.

Thyroid dysfunction as a late effect in childhood medulloblastoma: a comparison of hyperfractionated versus conventionally fractionated craniospinal radiotherapy.

PURPOSE: Primary hypothyroidism is a common sequela of craniospinal radiotherapy in the treatment of childhood medulloblastoma. Due to the strong radiobiologic rationale, hyperfractionation can reduce the delayed effects of radiation injury. METHODS AND MATERIALS: The authors compared the incidence of thyroid dysfunction after conventionally fractionated radiotherapy (Group A, n = 20 patients) vs. hyperfractionated radiotherapy (Group B, n = 12 patients) in a group of pediatric patients with posterior fossa primitive neuroectodermal tumor (PNET). RESULTS: The mean age at the time of tumor diagnosis was 7.4 years in Group A and 8.4 years in Group B. Thyroid function was evaluated yearly, with ultrasonographic examination every 2 years. The patients were followed after diagnosis for a mean of 10.8 years for Group A and 6.0 years for Group B. Approximately 80% of the Group A (16/20) and 33.3% of the Group B (4/12) patients developed primary hypothyroidism within a similar period after irradiation (4.2 vs. 3.5 years, respectively). Analysis by cumulative incidence function demonstrated a significant difference in the risk of developing thyroid dysfunction between these two groups of patients (p < 0.05). Ultrasonography showed reduced thyroid volume in 7 Group A patients and structural changes in 21 patients (17 Group A, 4 Group B cases); a thyroid benign nodule was detected in 2 Group A patients. CONCLUSIONS: The current study findings suggest that the use of hyperfractionated craniospinal radiotherapy in the treatment of childhood medulloblastoma is associated with a lower risk of these patients' developing late thyroid dysfunction.

Persistence of E2A/PBX1 transcripts in t(1;19) childhood acute lymphoblastic leukemia: correlation with chemotherapy intensity and clinical outcome.

The occurrence of t(1;19) translocation was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR) for the E2A/PBX1 hybrid message in a panel of 37 consecutive childhood acute lymphoblastic leukemias (ALLs). Three patients with B-precursor ALL were found to be positive at diagnosis and were re-tested during follow-up to assess the presence of minimal residual disease (MRD). Two of them became PCR-negative during treatment, whereas one remains positive 3 years after diagnosis. Since all three patients are presently in clinical and hematological complete remission, PCR detection of persistent E2A/ PBX1 transcript does not seem to affect significantly the DFS at 3 years. However, the predictivity for an eventual late relapse still remains to be assessed.

Rebound thymic hyperplasia following high dose chemotherapy and allogeneic BMT.

We describe a child with acute lymphoblastic leukemia who showed mediastinal widening 8 months after allogeneic BMT. Total thymectomy was carried out by the transcervical approach. Histologic examination showed only thymic hyperplasia. The immunohistologic investigation revealed a normal distribution of thymic cell elements, without evidence of clonal proliferation of lymphocytic subpopulations. This case supports the hypothesis that thymic hyperplasia following chemotherapy may be merely a rebound phenomenon. The patient had an uneventful postoperative recovery and remains in remission more than 1 year after BMT.

Human cord blood progenitors: kinetics, regulation and their use for hemopoietic reconstitution.

The high number of cord blood (CB) hematopoietic progenitors made possible CB transplantation in children with hematologic diseases. We collected and cryopreserved CB from siblings of 11 hematologic pediatric patients for possible transplant. The number of BFU-E+CFU-GEMM and CFU-GM was adequate for engraftment. However the possibility of CB transplantation in adolescents and adults is limited by the amount of CB that can be collected. We studied the possibility of expanding the pool of CB hematopoietic progenitors by preincubation of CB CD 34+ cells with several cytokines. After pre-exposition to rhIL-3, IL-1 beta, rIL-6, GM-CSF and stem cell factor (SCF) and cloning with SCF the number of hematopoietic progenitors increased 14-18 fold compared to basal values.

ABMT for children AML: Italian experience. GITMO-AIEOP Groups.

We report data from an Italian survey on ABMT in 93 AML children less than 14 years in 1st or 2nd remission performed in 15 Centers. Different conditioning regimens have been employed: BAVC, an original schedule of chemotherapy; TBI plus Cy and/or other drugs (TBI + CHT); other high dose chemotherapy schedules (HD CHT). 62 patients have been transplanted in 1st CR; 38 have been conditioned with BAVC, 16 with TBI + CHT and 8 with HD CHT. Relapses were 21 in the BAVC group (DFS = 35% at 66 months), 5 in the TBI group (DFS = 61% at 48 months) and 5 in the HD CHT group; overall DFS is 39% at 66 months. 31 patients have been transplanted in 2nd CR; 14 were conditioned with BAVC and 16 with TBI + CHT; 6 patients relapsed in the first group, DFS is 56% at 50 months; in the second group 2 early deaths and 3 relapses occurred, DFS is 65% at 65 months. 1 patient in 2nd CR, conditioned with HD CHT, died during aplasia. Overall DFS is 59% at 65 months. Although no final conclusions concerning ABMT in AML children may be drawn from this retrospective study because of heterogeneity of population and methods, results obtained in 2nd CR are clearly better to those obtained with standard chemotherapy alone, confirming the role of ABMT in this high risk category of patients.

Feasibility of high-dose chemotherapy and autologous peripheral blood stem cell transplantation in children with high grade osteosarcoma.

An Italian-Scandinavian treatment and research protocol with high-dose chemotherapy and double peripheral blood stem cell (PBSC) transplantation has been designed in an attempt to improve overall results of children with metastatic osteosarcoma (OST). Six patients, aged 12-17 years, underwent PBSC mobilization with CY 4 g/m2 and VP-16 600 mg/m2 followed by G-CSF (n = 4 with recurrent disease) or ifosfamide 15 g/m2 plus G-CSF (n = 2 with synchronous metastases). The target dose of CD34+ cells for two transplant procedures was 8 x 10(6)/kg or more; conditioning regimen for both the grafts consisted of carboplatin 375 mg/m2/day for 4 days and VP16 450 mg/m2/day for 4 days. The first transplant was planned 2-4 weeks after the mobilization, the second transplant 4-6 weeks after the first graft. In three patients a single course of CY-VP16 mobilised a total number of CD34+ sufficient for two transplants; in the patient who did not obtain the target dose of CD34+ cells a bone marrow harvest was added. In the two other children high-dose ifosfamide failed to achieve the required CD34+ number: one patient underwent a single transplant procedure, one patient was successfully mobilized with doxorubicin 90 mg/m2 plus G-CSF. Patients underwent a median of two collections (range 2-4). Leukapheresis resulted in the collection of a median of 8.9 CD34+ cells/kg (range 1.3-14.8). The median time to granulocyte count recovery to more than 0.5 x 10(9)/l was 10 days (range 9-14 days) after the first graft and 11 days (range 10-12 days) after the second graft, respectively. Platelets recovered to 50 x 10(9)/l at a median of 11 (range 10-30 days) and 13 days (range 10-28) respectively after the first and the second graft. Conditioning regimen was well tolerated in all patients with mild extra haematological toxicity, also following the second transplant. Two patients grafted with metastases at diagnosis are alive and disease free 3 and 7 months from the transplant. One of the four patients transplanted for recurrent disease developed pulmonary metastases 2 months after the procedure; one patient is alive with significant reduction of tumor mass 1 month after the first transplant, one patient is alive without evidence of disease 9 months from the second transplant and one after a complete metastasectomy (tumor necrosis >90%) which followed the second transplant. With the limits of the small number of cases and the short follow-up, these preliminary results show that this approach may be promising for the treatment of patients with metastatic OST who currently are not cured by conventional-dose regimens.