Fifteen-year follow-up of relapsed indolent non-Hodgkin lymphoma patients vaccinated with tumor-loaded dendritic cells.

We previously published the results of a pilot study showing that vaccination with tumor-loaded dendritic cells (DCs) induced both T and B cell response and produced clinical benefit in the absence of toxicity in patients with relapsed, indolent non-Hodgkin lymphoma (iNHL). The purpose of the present short report is to provide a 15-year follow-up of our study and to expand the biomarker analysis previously performed. The long-term follow-up highlighted the absence of particular or delayed toxicity and the benefit of active immunization with DCs loaded with autologous, heat-shocked and UV-C treated tumor cells in relapsed iNHL (5-year and 10-year progression-free survival (PFS) rates: 55.6% and 33.3%, respectively; 10-year overall survival (OS) rate: 83.3%). Female patients experienced a better PFS (p=0.016) and a trend towards a better OS (p=0.185) compared with male patients. Of note, we observed a non-negligible fraction of patients (22%) who experienced a long-lasting complete response. In a targeted gene expression profiling of pre-treatment tumor biopsies in 11 patients with available formalin-fixed, paraffin-embedded tissue, we observed that KIT, ATG12, TNFRSF10C, PBK, ITGA2, GATA3, CLU, NCAM1, SYT17 and LTK were differentially expressed in patients with responder versus non-responder tumors. The characterization of peripheral monocytic cells in a subgroup of 14 patients with available baseline blood samples showed a higher frequency of the subset of CD14++CD16+ cells (intermediate monocytes) in patients with responding tumors. Since in patients with relapsed iNHL the available therapeutic options are often incapable of inducing a long-lasting complete remission and can be sometimes characterized by intolerable toxicity, we think that the encouraging results of our long-term follow-up analysis represent a stimulus to further investigate the role of active vaccination in this specific setting and in earlier lines of therapy and to explore novel combinatorial strategies encompassing other innovative immunotherapy agents, such as immune-checkpoint inhibitors.

Cognitive decline in older long-term survivors from Non-Hodgkin Lymphoma: a multicenter cross-sectional study.

OBJECTIVES: To compare cognition in a group of older long-term survivors from Non-Hodgkin Lymphoma (NHL) and in a corresponding group of non-cancer controls of the same age. Functional status, polypharmacy and multimorbidity were also evaluated. METHODS: A cross-sectional study was performed in a population of 63 outpatient long-term survivors from NHL, aged 65 or more and 61 non-cancer controls. Socio-demographic, clinical and functional data were collected. Cognitive function was assessed through neuropsychological tests. RESULTS: NHL survivors showed a slightly worse functional status than controls, they were affected by more chronic conditions (3.4 vs 2.3; p = .003) and were taking a higher number of medications (3.4 vs 2.3; p = .03). The Mini Mental State Examination (MMSE) was not significantly different between the groups. NHL survivors performed worse than controls in executive functioning (Trail Making Test B-A 47.9 vs 32.1 p = .04, OR for Stroop test time over 75th percentile in survivors: 2.66; CI 95% 1.04-6.61; OR for Multiple Features Target Cancellation time over 75th percentile in survivors: 2.84; CI 95% 1.10-7.31). A small, statistically significant difference was also observed in verbal memory scores between the two groups. . CONCLUSIONS: The findings of this study suggest that, compared with non-cancer controls, older survivors from NHL may have a lower cognitive performance, especially in the executive functioning and attention domains, regardless of multimorbidity and polypharmacy. Further evidence from larger samples is needed to confirm such findings and better characterize cognitive decline in NHL survivors.

Obinutuzumab and miniCHOP for unfit patients with diffuse large B-cell lymphoma. A phase II study by Fondazione Italiana Linfomi.

OBJECTIVE: To evaluate activity and safety of obinutuzumab-miniCHOP (Ga101-miniCHOP) combination in older patients with Diffuse Large B-Cell Lymphoma (DLBCL) unfit to receive full dose immunochemotherapy. MATERIALS AND METHODS: We conducted a Simon's two-stage phase II multicenter trial to investigate response rate (primary endpoint) and safety of six courses of Ga101-miniCHOP in older patients with DLBCL (≥65 years), prospectively defined as unfit according to a simplified Comprehensive Geriatric Assessment (sCGA). RESULTS: Overall, 34 patients were enrolled (median age 82 years; range 68-89), with 27 out of the 33 eligible patients completing all six planned courses. Complete Remission (CR) rate was reported in fourteen patients (42%). After a median follow-up of sixteen months, the two-year Progression Free and Overall Survival (PFS and OS) were 49% (95% Confidence Interval (CI), 28 to 67) and 68% (95% CI, 49 to 81), respectively. The most frequent grade 3-4 adverse event was neutropenia in thirteen patients (26%). CONCLUSIONS: Based on the observed CR rate, study accrual was interrupted due to the very low probability of demonstrating the initial study hypothesis that Ga101-miniCHOP could improve results of historical data obtained with R-miniCHOP in this group of patients. Nonetheless, results achieved with the 33 treated patients confirm activity and good tolerability of the Ga101-miniCHOP regimen for older unfit adult patients with DLBCL.

Addition of Rituximab to Involved-Field Radiation Therapy Prolongs Progression-free Survival in Stage I-II Follicular Lymphoma: Results of a Multicenter Study.

PURPOSE: Rituximab (Rit) therapy added to involved-field radiation therapy (RT) has been proposed as an effective treatment for stage I-II follicular lymphoma (FL). The results of an observational multicenter study on the Rit-RT combination in limited-stage FL are here reported. METHODS AND MATERIALS: Data have been collected from 2 consecutive cohorts of 94 patients with stage I-II FL treated between 1985 and 2011 at 5 Italian institutions. All patients had grade 1-3a FL, a median age of 54 years (range: 25-82). The first 51 patients received RT alone (control group), while the subsequent series of 43 patients received 4 rituximab courses (375 mg/m(2), days 1, 8, 15, 22) before RT (Rit-RT). Molecular disease was evaluated by nested bcl-2/IgH PCR or clonal IgH rearrangement was available in 33 Rit-RT patients. RESULTS: At a median follow-up of 10.9 years (range: 1.8-22.9), the 10-year progression-free survival (PFS) and overall survival (OS) projections for the whole cohort were 57% and 87.5%, respectively. The 10-year PFS was significantly longer (P<.05) in the Rit-RT group (64.6%) compared to RT alone (50.7%), whereas the 10-year OS projections were not significantly different. On bivariate analysis controlling for stage, there was only a trend toward improved PFS for Rit-RT (HR, 0.55; P=.081). Follicular lymphoma international prognostic index and age were associated with OS but not with PFS on Cox regression analysis. Bone marrow molecular analysis showing PCR positivity at diagnosis was strongly associated with relapse risk upon univariate and multivariate analysis. CONCLUSIONS: This multicenter observational study suggests a potential benefit of adding rituximab to radiation therapy for stage I-II FL. The results of the currently ongoing randomized studies are required to confirm these results. The study underlines the importance of molecular disease monitoring also for patient with limited-stage disease.

Predictors of CD34+ cell mobilization and collection in adult men with germ cell tumors: implications for the salvage treatment strategy.

BACKGROUND: High-dose chemotherapy with tandem or triple carboplatin and etoposide course is currently the first curative choice for relapsing GCT. The collection of an adequate amount of hematopoietic (CD34(+)) stem cells is a priority. PATIENTS AND METHODS: We analyzed data of patients who underwent HDCT at 2 referral institutions. Chemotherapy followed by myeloid growth factors was applied in all cases. Uni- and multivariable models were used to evaluate the association between 2 prespecified variables and mobilization parameters. Analyses included only the first mobilizing course of chemotherapy and mobilization failures. RESULTS: A total of 116 consecutive patients underwent a mobilization attempt from December 1995 to November 2012. Mobilizing regimens included cyclophosphamide (CTX) 7 gr/m(2) (n = 39), cisplatin, etoposide, and ifosfamide (PEI) (n = 42), paclitaxel, cisplatin, and gemcitabine (TPG) (n = 11), and mixed regimens (n = 24). Thirty-seven percent were treated in first-line, 50% (n = 58) in second-line, 9.5% (n = 11) and 3.4% (n = 4) in third- and fourth-line settings, respectively. Six patients did not undergo HDCT because they were poor mobilizers, 2 in first- and second-line (1.9%), and 4 beyond the second-line (26.7%). In the multivariable model, third-line or later setting was associated with a lower CD34(+) cell peak/µL (P = .028) and a lower total CD34(+)/kg collected (P = .008). The latter was also influenced by the type of mobilizing regimen (P < .001). CONCLUSION: A decline in significant mobilization parameters was found, primarily depending on the pretreatment load. Results lend support to the role of CD34(+) cell mobilization in the therapeutic algorithm of relapsing GCT, for whom multiple HDCT courses are still an option, and potentially a cure.

Detection of minimal residual disease in hematopoietic progenitor cell harvests: lack of predictive value of peripheral blood and bone marrow analysis in mantle cell and indolent lymphoma.

Elimination of neoplastic cells from peripheral blood progenitor cells (PBPCs) is an important issue in transplantation-based high-dose chemotherapy in non Hodgkin's lymphoma (NHL). The capacity to reliably assess the presence of residual lymphoma cells in PBPCs is mandatory in designing this type of protocols. Polymerase chain reaction (PCR) amplification of molecular rearrangements is widely used to detect minimal residual disease (MRD) in NHL patients. Although concordant data can be obtained in most of the cases from peripheral blood (PB) and bone marrow (BM) at diagnosis, the relationship between these two compartments and the role of their analysis in predicting the molecular status of PBPCs is still an open issue. Here we report data about MRD analysis in BM, PB and PBPCs in a series of mantle cell and indolent NHL patients who underwent high-dose chemotherapy: discordant results were obtained comparing PB, BM and PBPC molecular data. In addition, differences were noted among these results if molecular analysis was performed using well-known rearrangements (i.e., bcl-1/IgH and bcl-2/IgH) or patient specific oligonucleotides. We conclude that neither BM nor PB are reliable in predicting the molecular status of PBPCs and that caution must be adopted in interpreting molecular data obtained using patient specific oligonucleotides.

Phase II study of sorafenib in patients with relapsed or refractory lymphoma.

The safety and activity of the multikinase inhibitor sorafenib were investigated in patients with relapsed or refractory lymphoproliferative disorders who received sorafenib (400 mg) twice daily until disease progression or appearance of significant clinical toxicity. The primary endpoint was overall response rate (ORR). Biomarkers of sorafenib activity were analysed at baseline and during treatment. Thirty patients (median age, 61 years; range, 18-74) received a median of 4 months of therapy. Grade 3-4 toxicities included hand/foot skin reactions (20%), infections (12%), neutropenia (20%) and thrombocytopenia (14%). Two patients achieved complete remission (CR), and two achieved partial remission (PR) for an ORR of 13%. Stable disease (SD) and progressive disease (PD) was observed in 15 (50%) and 11 patients (37%), respectively. The median overall survival (OS) for all patients was 16 months. For patients who achieved CR, PR and SD, the median time to progression and OS was 5 and 24 months, respectively. Compared with patients with PD, responsive patients had significantly higher baseline levels of extracellular signal-regulated kinase phosphorylation and autophagy and presented a significant reduction of these parameters after 1 month of therapy. Sorafenib was well tolerated and had a clinical activity that warrants development of combination regimens.

Long-term results of high-dose chemotherapy with autologous bone marrow or peripheral stem cell transplant as first salvage treatment for relapsed or refractory Hodgkin lymphoma: a single institution experience.

The introduction of high-dose (HD) chemotherapy (CT) and autologous stem cell (ASCT) or bone marrow transplant (ABMT) in the last two decades has improved the prognosis of patients with refractory or relapsed Hodgkin lymphoma (HL) over conventional-dose salvage CT. To evaluate the outcome of adult patients with HL treated with HD CT and ASCT or ABMT after failure or relapse from first-line treatment with CT +/- radiotherapy, we report the results of a retrospective analysis in 82 consecutive patients given HD CT and autologous transplant as second-line therapy between October 1984 and December 2006. Thirty-two patients were given sequential high-dose cytoreductive therapy while 50 received other conventional induction regimens. Seventy-three patients with chemoresponsive disease underwent the myeloablative phase, while eight patients had progressive disease during cytoreductive CT. After a median follow-up of 73 months, the 10-year progression-free survival (PFS) and overall survival (OS) were 57% and 51%, respectively. According to response to first-line treatment, PFS and OS were, respectively, 54% and 82% for patients with complete remission (CR) lasting 12 months or more; 49% and 51% for patients with CR less than 12 months; and 47% and 50% for patients who never achieved CR or progressed during first-line CT (induction failure). Response to cytoreductive CT significantly influenced outcome, with PFS and OS being, respectively, 56% and 68% vs. 44% and 47% (p = 0.009) in patients in CR versus patients not in CR after induction therapy. Treatment was well tolerated, and therapy related mortality was only 3.7%. These long-term results confirm that HD CT and ASCT or ABMT was feasible, safe, and very effective. Therefore, this therapeutic strategy may represent an active salvage approach even in the unfavorable group of patients with induction failure.

Radioimmunotherapy and secondary leukemia: a case report.

This study describes a patient with a relapsed, diffuse, large B cell lymphoma (DLBCL) treated with radioimmunotherapy (RIT) with yttrium-90 ((90)Y)-ibritumomab tiuxetan (Zevalin) who 5 months later developed acute myeloid leukemia (AML) with inversion of chromosome 16. Our data indicate that molecular biological techniques should be used in selected cases to integrate data obtained with standard cytogenetics: using RT-PCR we showed that inversion of chromosome 16 was already present before RIT, in striking contrast to the normal karyotype found with conventional cytogenetics. This approach will allow investigators to avoid misleading data and provide support for conclusions regarding the side effects of treatment.

Vaccination with autologous tumor-loaded dendritic cells induces clinical and immunologic responses in indolent B-cell lymphoma patients with relapsed and measurable disease: a pilot study.

Eighteen relapsed patients with measurable indolent non-Hodgkin lymphoma (NHL) were vaccinated with dendritic cells (DCs) loaded with killed autologous tumor cells. Six patients had objective clinical responses including 3 continuous complete responses (CRs) and 3 partial responses (PRs), with a median follow up of 50.5 months. Eight patients had stable disease, whereas 4 had progressive disease. Clinical responses were significantly associated with a reduction in CD4(+)CD25(+)FOXP3(+) regulatory T cells, an increase in CD3(-)CD56(dim)CD16(+) natural killer (NK) cells, and maturation of lymphocytes to the effector memory stage in either postvaccination peripheral blood or tumor specimen samples. In partial responding patients, vaccination significantly boosted the IFN-gamma-producing T-cell response to autologous tumor challenge. In one HLA-A*0201(+) patient who achieved CR, IL-4 release by circulating T cells in response to tumor-specific IgH-encoded peptides was also documented. Immunohistochemical analysis of tumor biopsies using biotin-conjugated autologous serum samples revealed a tumor-restricted humoral response only in the postvaccination serum from responding patients. Collectively these results demonstrate that vaccination with tumor-loaded DCs may induce both T- and B-cell responses and produces clinical benefits in indolent NHL patients with measurable disease. This study is registered with the Istituto Superiore di Sanità: http://www.iss.it with protocol number 7578-PRE 21-801.

High-dose yttrium-90-ibritumomab tiuxetan with tandem stem-cell reinfusion: an outpatient preparative regimen for autologous hematopoietic cell transplantation.

PURPOSE: To develop high-dose myeloablative therapy for CD20(+) non-Hodgkin's lymphoma (NHL) as a safe and widely applicable regimen. PATIENTS AND METHODS: Patients with relapsed/refractory (n = 25) or de novo high-risk (n = 5) NHL received one myeloablative dose of yttrium-90 ((90)Y)-ibritumomab tiuxetan after five chemotherapy courses, including three cycles of anthracycline- or platinum-containing regimens, one cycle of cyclophosphamide (4 to 7 g/m(2)), and one cycle of cytarabine (12 to 24 g/m(2)). The only exclusion criteria were CNS lymphoma and Eastern Cooperative Oncology Group performance status of more than 3. Primary end points were overall survival (OS) and event-free survival (EFS). Secondary end points included safety and applicability of high-dose (90)Y-ibritumomab tiuxetan. To minimize hematologic toxicity, stem cells were reinfused at days 7 and 14 after (90)Y-ibritumomab tiuxetan. RESULTS: Thirteen patients received (90)Y-ibritumomab tiuxetan 0.8 mCi/kg, and 17 patients received 1.2 mCi/kg. At 1.2 mCi/kg, the radiation absorbed by critical nonhematologic organs approached the protocol-defined upper safety limit, defining this as the recommended dose for subsequent studies. Hematologic toxicity was mild to moderate and of short duration. Infections occurred in 27% of patients (none had a severity grade greater than 3). After a median observation time of 30 months (range, 22 to 48 months), no myeloid secondary malignancy or chromosomal abnormality was observed, the OS rate was 87%, and the EFS rate was 69%. CONCLUSION: High-dose (90)Y-ibritumomab tiuxetan seems to be an innovative myeloablative regimen with unprecedented short-term toxicity and wide applicability. Further studies are required to assess its long-term safety and role in the management of CD20(+) NHL.

Rituximab induces effective clearance of minimal residual disease in molecular relapses of mantle cell lymphoma.

Molecular remission (MR) is associated with improved outcome in mantle cell lymphoma (MCL). If MR is not achieved, patients are at high risk of relapse. We retrospectively describe the molecular and clinical follow-ups of 4 patients with molecular relapses (M-rels) who were treated with rituximab. The 4 patients received rituximab-supplemented, high-dose sequential chemotherapy and autologous stem cell transplantation as induction treatment and achieved clinical remission and MR. M-rel was defined as polymerase chain reaction (PCR) positivity in 2 consecutive samples in the absence of clinical relapse. M-rels occurred at 3, 6, 39, and 52 months and were always confirmed by direct sequencing of the clonal rearrangement. Minimal residual disease was monitored by qualitative and real-time quantitative PCR. All patients received 4 courses of rituximab, with 2 additional infusions if PCR positivity remained. After 4-6 courses of rituximab, all patients re-entered MR. No clinical relapses were recorded at 3, 6, 18, and 62 months from treatment, although 1 patient had a second M-rel that was sensitive to rituximab. Our results indicate that rituximab is active against residual MCL cells and suggest that molecularly tailored maintenance therapy needs to be investigated in clinical trials.

Topical prophylaxis of conjunctivitis induced by high-dose cytosine arabinoside.

We investigated the efficacy of dexamethasone plus diclofenac eye drops as prophylaxis for conjunctivitis induced by high-dose (HD) cytarabine (Ara-C). Sixty patients were randomized to receive either dexamethasone (group A, n=29) or dexamethasone plus diclofenac (group B, n=31). Conjunctivitis was experienced by 13/29 (45%) patients in group A, and 4/31 (13%) patients in group B (p

High response rate and manageable toxicity with an intensive, short-term chemotherapy programme for Burkitt's lymphoma in adults.

UNLABELLED: A very short, intensive paediatric chemotherapy programme was tested in a consecutive monoinstitutional group of 22 adult Burkitt's lymphoma (BL) patients. After a 5-week induction phase of weekly infusions consisting of vincristine, cyclophosphamide, doxorubicin, high-dose (HD) methotrexate (MTX) plus leukovorin rescue, and intrathecal MTX or cytarabine (ARA-C), a consolidation phase including HD ARA-C plus cisplatin was given. Responding patients achieving less than complete response (CR) after completion of the initial induction phase, were promptly shifted to a high-dose, stem cell supported sequential chemotherapy schema (R-HDS). PATIENT CHARACTERISTICS: median age, 35.5 (range 18-76) years; Ann Arbor stage I-II/III-IV, 11/11; bulky disease, 15 patients; LDH > or = 460 U/l, 11 patients. The median duration of the chemotherapy programme was 62 d (range, 43-94 d). Seventeen patients achieved a CR (77%), one patient died of progressive disease and four partial responders following induction were converted to CR following R-HDS. Of 17 patients in CR, one died of infectious toxicity while in CR, and one relapsed at 30 months and died of progressive disease. After a median follow-up of 28.7 months (range, 6-158 months), 16 patients (73%) were in continued CR. Overall survival and progression-free survival were 77% [95% confidence interval (CI), 52-99%] and 68% (95% CI, 43-99%) respectively. Confirmation of these excellent efficacy and feasibility results by larger, multicentre and prospective studies is warranted.

Use of recombinant human growth hormone (rhGH) plus recombinant human granulocyte colony-stimulating factor (rhG-CSF) for the mobilization and collection of CD34+ cells in poor mobilizers.

The activity of recombinant human growth hormone (rhGH) in enhancing CD34(+) cell mobilization elicited by chemotherapy plus recombinant human granulocyte colony-stimulating factor (rhG-CSF) was evaluated in 16 hard-to-mobilize patients, that is, those achieving a peak of circulating CD34+ cells 10/microL or less, or a collection of CD34(+) cells equal to or less than 2 x 10(6)/kg. Patients who had failed a first mobilization attempt with chemotherapy plus rhG-CSF (5 microg/kg/d) were remobilized with chemotherapy plus rhG-CSF and rhGH (100 microg/kg/d). As compared with rhG-CSF, the combined rhGH/rhG-CSF treatment induced significantly higher (P < or =.05) median peak values for CD34(+) cells/microL (7 versus 29), colony-forming cells (CFCs)/mL (2154 versus 28,510), and long-term culture-initiating cells (LTC-ICs)/mL (25 versus 511). Following rhG-CSF and rhGH/rhG-CSF, the median yields of CD34(+) cells per leukapheresis were 1.1 x 10(6)/kg and 2.3 x 10(6)/kg (P < or =.008), respectively; the median total collections of CD34(+) cells were 1.1 x 10(6)/kg and 6 x 10(6)/kg (P < or =.008), respectively. No specific side effect could be ascribed to rhGH, except a transient hyperglycemia occurring in 2 patients. Reinfusion of rhGH/rhG-CSF-mobilized cells following myeloablative therapy resulted in prompt hematopoietic recovery. In conclusion, our data demonstrate that in poor mobilizers addition of rhGH to rhG-CSF allows the patients to efficiently mobilize and collect CD34(+) cells with maintained functional properties.

Dendritic cell viability is decreased after phagocytosis of apoptotic tumor cells induced by staurosporine or vaccinia virus infection.

BACKGROUND AND OBJECTIVES: Dendritic cells (DC) primed with tumor antigens can effectively mediate the regression of a variety of established solid malignancies in both murine and human models. Several experimental studies indicate that apoptotic bodies are an optimal source of tumor antigens for ex vivo priming of DC. However, the clinical use of killed tumor cells as a source of antigens will require an optimal methodology to induce effective tumor cell apoptosis. DESIGN AND METHODS: The goal of this study was to compare the efficiency of three agents for inducing neoplastic B lymphocyte apoptosis; staurosporine, infection by modified vaccinia (MVA) viral particles and ultraviolet C (UVC) radiation. RESULTS: The three methods were finely tuned to induce apoptosis in more than 90% of tumor cells after 24 hours of exposure. However, the viability of monocyte-derived DC, loaded with B-cell tumor apoptotic bodies induced by staurosporine or MVA viral particles, decreased dramatically within 48 hours after phagocytosis of the killed neoplastic cells. The persistence of the apoptosis-inducing agents in the apoptotic bodies and not in the tumor supernatant, was responsible for the observed damage to DC viability. In contrast, DC viability was not affected after uptake of tumor cells killed through UVC-irradiation. Furthermore, B-lymphoblastic cell line (LCL)-specific T cells were reactivated by DC loaded with apoptotic bodies induced by UVC-rays. INTERPRETATION AND CONCLUSIONS: Since the method used to induce tumor cell apoptosis might be detrimental to DC viability, these findings should be considered when designing anticancer vaccination programs.

Human bone marrow stromal cells suppress T-lymphocyte proliferation induced by cellular or nonspecific mitogenic stimuli.

CD2(+) T lymphocytes obtained from either the donor of bone marrow stromal cells (BMSCs) or a third party were cultured in mixed lymphocyte reactions (MLRs) with either allogeneic dendritic cells (DCs) or peripheral blood lymphocytes (PBLs). When autologous or allogeneic BMSCs were added back to T cells stimulated by DCs or PBLs, a significant and dose-dependent reduction of T-cell proliferation, ranging from 60% +/- 5% to 98% +/- 1%, was evident. Similarly, addition of BMSCs to T cells stimulated by polyclonal activators resulted in a 65% +/- 5% (P =.0001) suppression of proliferation. BMSC- induced T-cell suppression was still evident when BMSCs were added in culture as late as 5 days after starting of MLRs. BMSC-inhibited T lymphocytes were not apoptotic and efficiently proliferated on restimulation. BMSCs significantly suppressed both CD4(+) and CD8(+) T cells (65% +/- 5%, [P =.0005] and 75% +/- 15% [P =.0005], respectively). Transwell experiments, in which cell-cell contact between BMSCs and effector cells was prevented, resulted in a significant inhibition of T-lymphocyte proliferation, suggesting that soluble factors were involved in this phenomenon. By using neutralizing monoclonal antibodies, transforming growth factor beta1 and hepatocyte growth factor were identified as the mediators of BMSC effects. In conclusion, our data demonstrate that (1) autologous or allogeneic BMSCs strongly suppress T-lymphocyte proliferation, (2) this phenomenon that is triggered by both cellular as well as nonspecific mitogenic stimuli has no immunologic restriction, and (3) T-cell inhibition is not due to induction of apoptosis and is likely due to the production of soluble factors.