Dissection of DLBCL microenvironment provides a gene expression-based predictor of survival applicable to formalin-fixed paraffin-embedded tissue.

Background: Gene expression profiling (GEP) studies recognized a prognostic role for tumor microenvironment (TME) in diffuse large B-cell lymphoma (DLBCL), but the routinely adoption of prognostic stromal signatures remains limited. Patients and methods: Here, we applied the computational method CIBERSORT to generate a 1028-gene matrix incorporating signatures of 17 immune and stromal cytotypes. Then, we carried out a deconvolution on publicly available GEP data of 482 untreated DLBCLs to reveal associations between clinical outcomes and proportions of putative tumor-infiltrating cell types. Forty-five genes related to peculiar prognostic cytotypes were selected and their expression digitally quantified by NanoString technology on a validation set of 175 formalin-fixed, paraffin-embedded DLBCLs from two randomized trials. Data from an unsupervised clustering analysis were used to build a model of clustering assignment, whose prognostic value was also assessed on an independent cohort of 40 cases. All tissue samples consisted of pretreatment biopsies of advanced-stage DLBCLs treated by comparable R-CHOP/R-CHOP-like regimens. Results: In silico analysis demonstrated that higher proportion of myofibroblasts (MFs), dendritic cells, and CD4+ T cells correlated with better outcomes and the expression of genes in our panel is associated with a risk of overall and progression-free survival. In a multivariate Cox model, the microenvironment genes retained high prognostic performance independently of the cell-of-origin (COO), and integration of the two prognosticators (COO + TME) improved survival prediction in both validation set and independent cohort. Moreover, the major contribution of MF-related genes to the panel and Gene Set Enrichment Analysis suggested a strong influence of extracellular matrix determinants in DLBCL biology. Conclusions: Our study identified new prognostic categories of DLBCL, providing an easy-to-apply gene panel that powerfully predicts patients' survival. Moreover, owing to its relationship with specific stromal and immune components, the panel may acquire a predictive relevance in clinical trials exploring new drugs with known impact on TME.

Radiotherapy or chemotherapy for clinical stage IIA and IIB seminoma: a systematic review and meta-analysis of patient outcomes.

BACKGROUND: Outcomes of radiotherapy (RT) compared with chemotherapy (CT) remain poorly defined for clinical stage (CS) IIA and IIB seminoma. We aimed to evaluate the current role of the two treatment modalities in this setting of testicular seminoma. PATIENTS AND METHODS: A systematic review and meta-analysis (MA) was carried out to identify all evaluable studies. Search was limited to studies published after 1990 and included the Medline, Embase databases, and abstracts from ASCO (GU), ESMO, AUA, and ASTRO meetings up to April 2014. Sensitivity analyses were applied including the following: CSIIA and CSIIB, paraortic + iliac RT only in both stages, RT dose (≥30 versus <30 Gy), and PEB/EP regimens only. RESULTS: Thirteen studies have been selected for MA on relapse outcome. No randomized trials compared RT and CT. There were 4 prospective and 9 retrospective studies, with a total of 607 patients receiving RT and 283 patients CT. The pooled relapse rate (RR) was similar between the RT [0.11, 95% confidence interval (CI) 0.08-0.14, P for heterogeneity = 0.096, I(2) = 38%] and CT groups (0.08, 95% CI 0.01-0.15, P for heterogeneity <0.001, I(2) = 82.5%). However, in the sensitivity analysis, the pooled RR for RT in CSIIB was 0.12 (95% CI 0.06-0.17) while it was 0.05 (95% CI 0-0.11) for CT. Long-term side-effects and incidence of second cancers were more frequently reported following RT. The overall incidence of nontesticular second malignancies was 0.04 (95% CI 0.01-0.02) in the RT group and 0.02 (95% CI 0.003-0.04) in the CT group. CONCLUSIONS: Although RT and CT appeared to be equal options in CSIIA and IIB seminoma, a trend in favor of CT for a lower incidence of side-effects and RR in CSIIB was found. This evidence is limited by the retrospective quality of studies and their small sample size.

High-dose sequential chemotherapy (HDS) versus PEB chemotherapy as first-line treatment of patients with poor prognosis germ-cell tumors: mature results of an Italian randomized phase II study.

BACKGROUND: In the late 1990s, the use of high-dose chemotherapy (HDCT) and stem-cell rescue held promise for patients with advanced and poor prognosis germ-cell tumors (GCT). We started a randomized phase II trial to assess the efficacy of sequential HDCT compared with cisplatin, etoposide, and bleomycin (PEB). PATIENTS AND METHODS: Patients were randomly assigned to receive four cycles of PEB every 3 weeks or two cycles of PEB followed by a high-dose sequence (HDS) comprising HD-cyclophosphamide (7.0 g/m(2)), 2 courses of cisplatin and HD-etoposide (2.4 g/m(2)) with stem-cell support, and a single course of HD-carboplatin [area under the curve (AUC) 27 mg/ml × min] with autologous stem-cell transplant. Postchemotherapy surgery was planned on responding residual disease in both arms. The primary end point was progression-free survival (PFS). The study was designed to detect a 30% improvement of 5-year PFS (from 40% to 70%), with 80% power and two-sided α at 5%. RESULTS: From December 1996 to March 2007, 85 patients were randomized: 43 in PEB and 42 in HDS arm. Median follow-up was 114.2 months [interquartile range (IQR): 87.7-165.8]. Complete or partial response with normal markers (PRm-) were obtained in 28 (65.1%) and 29 (69.1%) patients, respectively. Five-year PFS was 55.8% [95% confidence interval (CI) 42.8-72.8] and 54.8% (95% CI 41.6%-72.1%) in PEB and HDS arm, respectively (log-rank test P = 0.726). Five-year overall survival was 62.8% (95% CI 49.9-79.0) and 59.3% (95% CI 46.1-76.3). One toxic death (PEB arm) was recorded. CONCLUSIONS: The study failed to meet the primary end point. Furthermore, survival estimates of conventional-dose chemotherapy higher than expected should be accounted for and will likely limit further improvements in the first-line setting. CLINICALTRIALS.GOV: NCT02161692.

Analysis of plasma cytokines and angiogenic factors in patients with pretreated urothelial cancer receiving Pazopanib: the role of circulating interleukin-8 to enhance the prognostic accuracy.

BACKGROUND: Pazopanib achieved the end point of clinical activity in pretreated patients with urothelial cancer in a single-group, phase 2 trial. The objective was to identify biological predictors of clinical benefit to pazopanib in these patients. METHODS: EDTA blood samples were collected at baseline (T0) and after 4 weeks (T1) of treatment, together with radiological imaging in all 41 patients to analyse plasma circulating angiogenic factor levels by multiplex ELISA plates. Changes from T0 to T1 in marker levels were matched with response with the covariance analysis. Univariable and multivariable analyses evaluated the association with overall survival (OS), adjusted for prespecified clinical variables. Net reclassification improvement (NRI) tested the performance of the recognised Cox model. RESULTS: Increasing IL8(T1) level associated with lower response probability at covariance analysis (P=0.010). Both IL8(T0) (P=0.019) and IL8(T1) (P=0.004) associated with OS and the prognostic model, including clinical variables and IL8(T1) best-predicted OS after backward selection. The NRI for this model was 39%.When analysed as a time-varying covariate, IL8(T1) level<80 pg ml(-1) portended significantly greater response (∼80%) and 6-month OS (∼60%) probability than level ≥ 80. CONCLUSION: IL8-level changes during pazopanib allowed for a prognostic improvement and were associated with response probability.

PF-03446962, a fully-human monoclonal antibody against transforming growth-factor ß (TGFß) receptor ALK1, in pre-treated patients with urothelial cancer: an open label, single-group, phase 2 trial.

Despite a compelling preclinical rationale for the use of anti-angiogenic drugs in urothelial cancer (UC), short-living responses have been observed in clinical trials. PF-03446962 is a novel monoclonal antibody against Activin Receptor-Like Kinase-1 (ALK1), a type I subclass of the TGFß receptor, with dose-dependent anti-angiogenic activity. An open label, single-group, phase 2 trial of PF-03446962 was conducted in salvage setting. Patients failing at least one chemotherapy regimen were eligible. Design provided PF-03446962 10 mg/Kg intravenously fortnightly until disease progression (PD) or unacceptable toxicity. Two-month progression-free survival (PFS) was the primary endpoint. The trial was registered with ClinicalTrials.gov, number NCT01620970. Fourteen patients were enrolled from October 2012 to July 2013. Median age was 64 years (interquartile range [IQR]: 58.2-69.5), 9 patients had a Bellmunt score of 1-2, median number of prior drugs was 3. One stable disease and 13 PD were recorded and the study met the futility stopping rule of interim analysis. Median PFS was 1.8 months (95 %CI, 1.4-2.0). After a median follow up of 7.4 months (IQR 4.5-10.9), 8 patients are alive. Median overall survival (OS) was 8 months (95 %CI, 2.9-not estimable). Most common toxicities were thrombocytopenia (G1-2 in 5 cases, persistent G3 in one, with 3 dose delays and 1 dose interruption), fatigue and abdominal pain (G1-2 in 4 cases each). Impairment of quality of life (ESAS score) was observed as well as an increase from baseline to +2 month median levels of vascular endothelial growth factor (VEGF) and interleukin-8. PF-03446962 had no activity as single drug in refractory UC and we do not recommend further investigation outside of the combination with agents targeting the VEGF receptor axis.

Modified cisplatin, etoposide, and ifosfamide (PEI) salvage therapy for male germ cell tumors: long-term efficacy and safety outcomes.

BACKGROUND: Since 1985, we introduced a modified combination of etoposide, ifosfamide, and cisplatin (PEI) as second-line therapy of adult male germ cell tumors with the aim to reduce toxic effect while maintaining efficacy over the original regimen. PATIENTS AND METHODS: Patients received four cycles of ifosfamide at 2.5 g/m(2) on days 1-2, etoposide, and cisplatin at 100 and 33 mg/m(2), respectively, on days 3-5 every 21 days, followed by surgery. Results were stratified according to the International Germ Cell Consensus Classification Group-2 (IGCCCG-2). RESULTS: From February 1985 to January 2012, 189 patients were treated. 72.6% were IGCCCG-2 intermediate-to-very high risk. Thirty-five patients (18.5%) had a complete response, 67 (35.4%) a marker normalization (PRm-). Median follow-up was 122.1 months (inter-quartile range [IQR]: 71.4-232.0). Two-year progression-free and 5-year overall survival were 34.3% [95% confidence interval (CI) 28.1% to 41.9%] and 42.1% (95% CI 35.3% to 50.2%), respectively. Survival estimates compared favorably with those obtained by conventional dose chemotherapy (CDCT) regimens in each prognostic category. 70.4% of grade 3-4 neutropenia (25.5% febrile neutropenia), 48.1% thrombocytopenia, 21.2% anemia, 3.2% neurotoxic effect, and no severe renal toxic effect were recorded. CONCLUSION: Dose-modified Italian PEI should be considered as an appropriate benchmark for CDCT in the first salvage setting.

An expanded peripheral T cell population to a cytotoxic T lymphocyte (CTL)-defined, melanocyte-specific antigen in metastatic melanoma patients impacts on generation of peptide-specific CTLs but does not overcome tumor escape from immune surveillance in metastatic lesions.

It is not known if immune response to T cell-defined human histocompatibility leukocyte antigen (HLA) class I-restricted melanoma antigens leads to an expanded peripheral pool of T cells in all patients, affects cytotoxic T lymphocyte (CTL) generation, and correlates with anti-tumor response in metastatic lesions. To this end, a limiting dilution analysis technique was developed that allowed us to evaluate the same frequency of peptide-specific T cells as by staining T cells with HLA-peptide tetrameric complexes. In four out of nine patients, Melan-A/Mart-1(27-35)-specific CTL precursors (CTLp) were >/=1/2,000 peripheral blood lymphocytes and found mostly or only in the CD45RO(+) memory T cell subset. In the remaining five patients, a low (<1/40,000) peptide-specific CTLp frequency was measured, and the precursors were only in the CD45RA(+) naive T cell subset. Evaluation of CTL effector frequency after bulk culture indicated that peptide-specific CTLs could be activated in all patients by using professional antigen-presenting cells as dendritic cells, but CTLp frequency determined the kinetics of generation of specificity and the final number of effectors as evaluated by both limiting dilution analysis and staining with HLA-A*0201-Melan-A/Mart-1 tetrameric complexes. Immunohistochemical analysis of 26 neoplastic lesions from the nine patients indicated absence of tumor regression in most instances, even in patients with an expanded peripheral T cell pool to Melan-A/Mart-1 and whose neoplastic lesions contained a high frequency of tetramer-positive Melan-A/Mart-1-specific T cells. Furthermore, frequent lack of a "brisk" or "nonbrisk" CD3(+)CD8(+) T cell infiltrate or reduced/absent Melan-A/Mart-1 expression in several lesions and lack of HLA class I antigens were found in some instances. Thus, expansion of peripheral immune repertoire to Melan-A/Mart-1 takes place in some metastatic patients and leads to enhanced CTL induction after antigen-presenting cell-mediated selection, but, in most metastatic lesions, it does not overcome tumor escape from immune surveillance.

Immune reconstitution inflammatory syndrome associated with Aspergillus terreus pulmonary infection in an autologous stem cell transplant recipient.

We describe an autologous stem cell transplant recipient who developed immune reconstitution inflammatory syndrome (IRIS) associated with Aspergillus terreus invasive pulmonary infection after recovery from neutropenia. Clinical and radiological worsening of pulmonary invasive aspergillosis coincident with a robust decline of serum galactomannan values and rising neutrophil counts should be interpreted as IRIS and should not require changes to antifungal therapy.

Proviral DNA of Moloney leukemia virus: purification and visualization.

Closed-circular proviral DNA of Moloney leukemia virus has been purified from a 10(7) excess of cellular and mitochondrial DNA. The DNA can be visualized in the electron microscope and has the contour length of a molecule with a moleculecular weight of about 5.5 + 10(6). Electron microscopic observation of a hybrid between viral RNA and this circular DNA confirms the viral origin of this molecule.

Primary diffuse large B-cell lymphoma of the breast: prognostic factors and outcomes of a study by the International Extranodal Lymphoma Study Group.

BACKGROUND: Primary diffuse large B-cell lymphoma (DLBCL) of breast is rare. We aimed to define clinical features, prognostic factors, patterns of failure, and treatment outcomes. PATIENTS AND METHODS: A retrospective international study of 204 eligible patients presenting to the International Extranodal Lymphoma Study Group-affiliated institutions from 1980 to 2003. RESULTS: Median age was 64 years, with 95% of patients presenting with unilateral disease. Median overall survival (OS) was 8.0 years, and median progression-free survival 5.5 years. In multifactor analysis, favourable International Prognostic Index score, anthracycline-containing chemotherapy, and radiotherapy (RT) were significantly associated with longer OS (each P < or = 0.03). There was no benefit from mastectomy, as opposed to biopsy or lumpectomy only. At a median follow-up time of 5.5 years, 37% of patients had progressed--16% in the same or contralateral breast, 5% in the central nervous system, and 14% in other extranodal sites. CONCLUSIONS: The combination of limited surgery, anthracycline-containing chemotherapy, and involved-field RT produced the best outcome in the pre-rituximab era. A prospective trial on the basis of these results should be pursued to confirm these observations and to determine whether the impact of rituximab on the patterns of relapse and outcome parallels that of DLBCL presenting at other sites.

Allogeneic stem cell transplantation following reduced-intensity conditioning can induce durable clinical and molecular remissions in relapsed lymphomas: pre-transplant disease status and histotype heavily influence outcome.

The safety and efficacy of reduced-intensity conditioning (RIC) followed by allogeneic stem cell transplantation (SCT) for relapsed lymphomas remains unresolved. We conducted a prospective, multicentered, phase II trial. A total of 170 relapsed/refractory lymphomas received a RIC regimen followed by SCT from sibling donors. The primary study end point was non-relapse mortality (NRM). Histologies were non-Hodgkin's lymphomas (NHL) (indolent (LG-NHL), n=63; aggressive (HG-NHL), n=61; mantle cell lymphoma (MCL), n=14) and Hodgkin's disease (HD, n=32). Median follow-up was 33 months (range, 12-82). The results show that frequencies were as follows: cumulative NRM at 3 years, 14%; acute and chronic graft-versus-host disease (GVHD) 35 and 52%, respectively; 3-year overall survival (OS), 69% for LG-NHL, 69% for HG-NHL, 45% for MCL and 32% for HD (P=0.058); and 3-year relapse incidence, 29, 31, 35 and 81%, respectively (P<0.001). Relapse risk differed significantly at 3 years between follicular lymphoma (FL) and chronic lymphocytic leukemia (CLL) (14 versus 46%, P=0.04). Molecular remission occurred in 94 and 40% (P=0.002) of patients with FL and CLL, respectively. On multivariate analysis, OS was influenced by chemorefractory disease (hazard ratio (HR)=3.6), diagnosis of HD (HR=3.5), and acute GVHD (HR=5.9). RIC allogeneic SCT is a feasible and effective salvage strategy in both indolent and aggressive NHL.

Prolonged survival in poor-risk diffuse large B-cell lymphoma following front-line treatment with rituximab-supplemented, early-intensified chemotherapy with multiple autologous hematopoietic stem cell support: a multicenter study by GITIL (Gruppo Italiano Terapie Innovative nei Linfomi).

A prospective multicenter program was performed to evaluate the combination of rituximab and high-dose (hd) sequential chemotherapy delivered with multiple autologous peripheral blood progenitor cell (PBPC) support (R-HDS-maps regimen) in previously untreated patients with diffuse large B-cell lymphoma (DLB-CL) and age-adjusted International Prognostic Score (aaIPI) score 2-3. R-HDS-maps includes: (i) three APO courses; (ii) sequential administration of hd-cyclophosphamide (CY), hd-Ara-C, both supplemented with rituximab, hd-etoposide/cisplatin, PBPC harvests, following hd-CY and hd-Ara-C; (iii) hd-mitoxantrone (hd-Mito)/L-Pam + 2 further rituximab doses; (iv) involved-field radiotherapy. PBPC rescue was scheduled following Ara-C, etoposide/cisplatin and Mito/L-Pam. Between 1999 and 2004, 112 consecutive patients aged <65 years (74 score 2, 38 score 3) entered the study protocol. There were five early and two late toxic deaths. Overall 90 patients (80%) reached clinical remission (CR); at a median 48 months follow-up, 87 (78%) patients are alive, 82 (73%) in continuous CR, with 4 year overall survival (OS) and event-free survival (EFS) projections of 76% (CI 68-85%) and 73% (CI 64-81%), respectively. There were no significant differences in OS and EFS between subgroups with Germinal-Center and Activated B-cell phenotype. Thus, life expectancy of younger patients with aaIPI 2-3 DLB-CL is improved with the early administration of rituximab-supplemented intensive chemotherapy compared with the poor outcome following conventional chemotherapy.

Current status and future perspectives for yttrium-90 ((90)Y)-ibritumomab tiuxetan in stem cell transplantation for non-Hodgkin's lymphoma.

Haematopoietic SCT is currently considered a therapeutic option mainly in relapsed or refractory non-Hodgkin's lymphoma (NHL) owing to high post-transplantation relapse rates and significant toxicity of conventional myeloablative conditioning for allogeneic SCT. Radiolabelled immunotherapy combines the benefits of monoclonal antibody targeting with therapeutic doses of radiation, and is a promising advance in the treatment of malignant lymphomas. It is now under investigation as a component of conditioning prior to SCT, with the aim of improving outcomes following SCT without increasing the toxicity of high-dose chemotherapy pre-transplant conditioning. An expert panel met at a European workshop in November 2006 to review the latest data on radiolabelled immunotherapy in the transplant setting, and its potential future directions, with a focus on (90)Y-ibritumomab tiuxetan. They reviewed data on the combination of standard/high/escalating dose (90)Y-ibritumomab tiuxetan with high-dose chemotherapy, and high/escalating dose (90)Y-ibritumomab tiuxetan as the sole myeloablative agent, prior to autologous SCT, and also (90)Y-ibritumomab tiuxetan as a component of reduced intensity conditioning prior to allogeneic SCT. The preliminary data are highly promising in terms of conditioning tolerability and patient outcomes following transplant; further phase II studies are now needed to consolidate these data and to investigate specific patient populations and NHL subtypes.

Long-term follow-up of patients with peripheral T-cell lymphomas treated up-front with high-dose chemotherapy followed by autologous stem cell transplantation.

We report the results of two prospective phase II studies investigating the role of high-dose sequential chemotherapy, followed by autologous stem cell transplantation (ASCT) in 62 patients with advanced stage peripheral T-cell lymphomas (PTCLs) at diagnosis. Conditioning regimen consisted of mitoxantrone (60 mg/m2) and melphalan (180 mg/m2) or carmustine, etoposide, Ara-C and melphalan followed by peripheral blood stem cell autografting. In an intent-to-treat analysis, 46 out of 62 patients (74%) completed the whole programme, whereas 16 patients did not undergo ASCT, mainly because of disease progression. At a median follow-up of 76 months, the estimated 12-year overall (OS), disease-free and event-free survival (EFS) were 34, 55 and 30%, respectively. OS and EFS were significantly better in patients with anaplastic lymphoma-kinase (ALK)-positive anaplastic large-cell lymphoma (ALCL), as compared with the remaining PTCL. Multivariate analysis showed that patients attaining complete remission (CR) before ASCT had a statistically significant benefit in terms of OS and EFS (P<0.0001). Overall treatment-related mortality rate was 4.8%. In conclusion, our findings indicate (1) up-front high-dose therapy and ASCT are feasible, but could induce a high rate of long-term CR only in patients with ALK-positive ALCL and (2) the achievement of CR before autografting is a strong predictor of better survival.

Early reduction of serum TARC levels may predict for success of ABVD as frontline treatment in patients with Hodgkin Lymphoma.

BACKGROUND: Many efforts have been made to predict prognosis of newly diagnosed Hodgkin Lymphoma (HL) patients. Objective of this study was to investigate the association between early reduction of Thymus and Activation-Regulated Chemokine after the first ABVD cycle (TARC-1) and prognosis of HL patients. METHODS: Serum samples of 116 HL patients were collected at baseline, after every ABVD cycle and during follow-up. The 99th centile of TARC distribution in a group of 156 independent healthy subjects (800pg/ml) was considered as cut-off for discriminating between abnormal and normal TARC values. FINDINGS: 101 patients out of 116 had baseline TARC above 800pg/ml (median value 27515pg/ml (IQR, 11001-68139)) and were the object of this analysis. TARC-1 significantly decreased to a median value of 556pg/ml (IQR, 378-977pg/ml). TARC-1 values below 800pg/ml were associated with success of therapy (p=0.0003) and PET-2 negativity (p=0.001). TARC-1≤800pg/ml identified a population with a significantly higher 5-years PFS in the whole cohort (90.1% vs 55.6%; p<0.0001) and in both subgroups of advanced (p=0.003) and early stage patients (p=0.021). At multivariable analysis, TARC-1 was significant independent predictor of PFS (p=0.0035). INTERPRETATION: Early reduction of TARC serum levels can predict success of treatment, being associated with achievement of interim PET-2 negative and favorable long-term outcome in HL patients receiving ABVD as front-line therapy.

Effect of age and previous autologous transplantation on nonrelapse mortality and survival in patients treated with reduced-intensity conditioning and allografting for advanced hematologic malignancies.

PURPOSE: Older age and a previously failed autologous stem-cell transplantation (SCT) are poor prognostic factors for patients receiving myeloablative conditioning and allogeneic SCT. Reduced-intensity conditioning (RIC) regimens achieved a significant reduction of treatment-related mortality, but the influence of previously described risk factors on the outcome of this novel transplantation strategy have not been fully analyzed yet. PATIENTS AND METHODS: One hundred fifty patients with advanced hematologic malignancies received a RIC regimen containing thiotepa (10 mg/kg), fludarabine (60 mg/m2), and cyclophosphamide (60 mg/kg), followed by an allogeneic transplantation from an HLA-identical sibling donor. Patients were divided into two cohorts according to age; 90 patients were younger than 55 years, and 60 patients were 55 years old or older. The other pretransplantation characteristics were fairly balanced. RESULTS: Actuarial 5-year nonrelapse mortality (NRM) rate was not statistically different between the groups (13% in the younger group and 19% in the older group). By univariate and multivariate analysis, NRM was significantly higher in older patients who previously experienced failure with an autograft. The occurrence of grade 3 to 4 acute graft-versus-host disease (GVHD) or extensive chronic GVHD was associated with a higher NRM in both age cohorts. Overall survival (OS) was not statistically different between the younger (66%) and older groups (61%). By multivariate analysis, refractory disease was associated with a worse OS irrespective of age group. CONCLUSION: RIC transplantations show a rather low NRM, and age > or = 55 years per se cannot be considered a risk factor anymore. The timing of transplantation and novel strategies for the prevention of severe GVHD could further improve patient outcome.

Activity of a monoclonal antibody-saporin-6 conjugate against B-lymphoma cells.

A monoclonal antibody reactive with the immunoglobulin heavy chain (TEC IgM) has been conjugated to saporin-6 (SAP), which is the major ribosome-inactivating protein from the seeds of the plant Saponaria officinalis. Studies with Burkitt's lymphoma cell line Bjab 113 demonstrate that this immunotoxin is capable of killing 3 logs (99.9%) of clonogenic lymphoma cells after a 2-hour incubation. The presence of human bone marrow inhibits the activity of the conjugate. However, full potency of TEC IgM-SAP immunotoxin is restored by adding 1 mM amantadine to the incubation medium. The reaction is highly specific and is inhibited by the presence of excess anti-mu-antibody or human serum. Clonal growth of other Burkitt's lymphoma cell lines is inhibited to a lesser extent by the immunotoxin. The presence of surface IgM on the different cell lines is directly correlated to target cell killing by TEC IgM-SAP. Isolation of Bjab 113 clones surviving treatment demonstrates that only a minority are truly resistant and that the others randomly escape the treatment. The highly potent and specific activity of this conjugate in the presence of bone marrow buffy coat and its exceptionally rapid onset of action make this conjugate a good candidate for the ex vivo elimination of neoplastic cells from the bone marrow of non-Hodgkin's lymphoma patients.

Autologous dendritic cells derived from CD34+ progenitors and from monocytes are not functionally equivalent antigen-presenting cells in the induction of melan-A/Mart-1(27-35)-specific CTLs from peripheral blood lymphocytes of melanoma patients with low frequency of CTL precursors.

Peptide presentation by autologous dendritic cells (DCs) is a new tool to activate tumor antigen-specific T cells in melanoma patients. However, it is not known whether autologous DCs, differentiated by two of the most efficient protocols (from CD34+ progenitors or from monocytes), are equally effective as professional antigen-presenting cells (APCs) when the patients have a low frequency of peptide-specific precursors. To this end, a limiting dilution assay was applied to evaluate the frequency of antigen-specific CTL precursors (CTLps) in peripheral blood of HLA-A*0201+ melanoma patients. Then, from two melanoma patients showing low frequency of CTLps to melanoma antigen-A/melanoma antigen recognized by T cell (Melan-A/Mart-1)(27-35) peptide, autologous DCs were differentiated from granulocyte colony-stimulating factor-mobilized CD34+ progenitors or from monocytes. CD34+- and monocyte-derived DCs were characterized by a similar proportion of CD1a+ cells expressing HLA class II antigens and CD54, CD80, and CD86 molecules. Both types of DC presented Melan-A/Mart-1(27-35) and tyrosinase(369-377) peptides to melanoma-specific CTL clones and were equally effective as peptide-pulsed APCs in the activation of influenza A matrix(58-66)-specific CTLs from high-frequency precursors (1294/10(6) and 1789/10(6) lymphocytes in the two patients). However, efficient activation of Melan-A/Mart-1(27-35)-specific CTLs from low-frequency precursors (158/10(6) and 77/10(6) lymphocytes) of the two patients was markedly dependent on the use of peptide-loaded CD34+-derived DCs. These results suggest that CD34+- and monocyte-derived DCs are not functionally equivalent APCs for the activation of low-frequency peptide-specific CTLps.

Immunotoxin-mediated inhibition of chronic lymphocytic leukemia cell proliferation in humans.

We evaluated the cytotoxicity of the immunotoxin OKT1-SAP on fresh B-chronic lymphocytic leukemia (B-CLL) cells from 31 consecutive patients. OKT1-SAP comprised the OKT1 (CD5) monoclonal antibody disulfide linked to saporin-6 (SAP) ribosome-inactivating protein from the plant Saponaria officinalis. The effect of OKT1-SAP on target CD5-positive B-CLL cells was estimated using an in vitro proliferation inhibition assay in which control or OKT1-SAP-treated B-CLL cells were induced to proliferate by sequential stimulation with insolubilized anti-C3b receptor CB04 (CD35) antibody and low molecular weight B-cell growth factor. In 90% of patients, OKT1-SAP specifically suppressed B-CLL cell proliferation in a dose-related manner (50% inhibitory concentration, 4.0-6.8 nM). Taken together the findings reported in this article provide information relevant to the clinical development of immunotoxins because: (a) the in vitro conditions under which B-CLL cell proliferation is inhibited by OKT1-SAP are achievable in vivo without nonspecific toxicity according to our previous toxicology and pharmacokinetics studies in primates; and (b) the B-CLL cell proliferation inhibition assay described here provides a basis for future comparative studies.