Allo-SCT conditioning for myelodysplastic syndrome and acute myeloid leukemia with clofarabine, cytarabine and ATG

The application of myeloablative Allo-SCT is limited by its associated morbidity and mortality. Reduced-intensity conditioning regimens attempt to diminish these, but are associated with a higher risk of disease relapse. Given the evidence of activity of clofarabine and cytarabine in myelodysplastic syndrome/acute myeloid leukemia (MDS/AML), we explored a novel reduced-intensity conditioning regimen based on this backbone. Patients received clofarabine 40 mg/m(2) i.v. on days -6 to -2, cytarabine 1 g/m(2) i.v. on days -6 to -2 and anti-thymocyte globulin (ATG) 1 mg/kg on day -4 and 2.5 mg/kg x 2 days on days -3 and -2. Seven patients were enrolled. Their median age was 54 years; three were with MDS and four with AML. The median duration of neutropenia was 14 days and that of thrombocytopenia was 22 days. Toxicities included hand-foot syndrome (57% grade 2), elevated alanine aminotransferase (ALT) (57% grade 3), elevated aspartate aminotransferase (AST) (86% grade 3) and hyperbilirubinemia (29% grade 3-5). No acute GVHD was observed. Enrollment to the trial was halted after three of the first seven patients expired on days +15, +26 and +32. Three of the four surviving patients have relapsed with a median TTP of 152 days. This regimen was not sufficiently immunosuppressive to ensure engraftment, and was associated with substantial morbidity and mortality.

Phase I study for poor-prognosis lymphoma: Augmentation of the “BEAM” regimen with escalating dose melphalan using amifostine cytoprotection and autologous hematopoietic stem cell transplantation — a preliminary report

We and others have previously shown that the use of amifostine (Ethyol; MedImmune Inc, Gaithersburg, MD) can ameliorate certain regimen-related toxicities of high-dose melphalan (HD-MEL) in the autologous hematopoietic stem cell transplant setting. Our recent experience indicated that the maximum tolerated dose of HD-MEL plus autologous hematopoietic stem cell transplant could be increased from approximately 200 mg/m2 to at least 280 mg/m2 with amifostine. Although a dose-limiting toxicity was not clearly identified, atrial fibrillation was noted in several patients. Phase II trials using this regimen have been reported in lymphoma and myeloma. Nonetheless, it is unlikely that single agent therapy, regardless of dose, will be highly curative in advanced hematologic malignancy. Thus, we used amifostine to permit dose escalation of HD-MEL within the BEAM (BCNU/etoposide/arabinosylcytosine/HD-MEL) combination chemotherapy regimen before autologous hematopoietic stem cell transplant in selected patients with lymphoma. Patient entry at the starting dose (ie, HD-MEL 140 mg/m2) has been completed without the development of severe regimen-related toxicities. This trial is ongoing.

Effects of the farnesyl transferase inhibitor R115777 on normal and leukemic hematopoiesis

Patients with acute myelogenous leukemia or myelodysplastic syndrome may respond to farnesyl transferase inhibitors (FTIs) with partial or complete response rates noted in about 30% of such patients. FTIs prevent the attachment of a lipid farnesyl moiety to dependent proteins prior to their insertion into the plasma membrane and thereby prevent activity of these prenylation-dependent proteins, but their mechanism of tumor suppression remains unknown. Many patients receiving FTIs do experience myelosuppression. In this work, the in vitro effects of the FTI, R115777 on normal and leukemic hematopoiesis have been examined as have its effects on apoptosis induction and cell cycle profile in both leukemic blasts and normal CD34+ cells. R115777 was inhibitory to normal CD34+ cell proliferation and to leukemic blast cells, but did not affect long-term culture initiating cell frequency nor NOD-SCID reconstituting capacity. No induction of apoptosis or cell cycle changes were noted in AML blasts. These data suggest that myelosuppression with R115777 occurs largely at the intermediate to late progenitor stage of hematopoiesis and that cyclic use might avoid long-term marrow suppression.

Impact of mobilized blood progenitor cell quality determined by the CFU-GM/CD34+ ratio on rapid engraftment after blood stem cell transplantation

To find a parameter to predict the quality of collected mobilized CD34+ blood as hemopoietic reconstituting cells, the ratio of CFU-GM to CD34+ cells was examined. One hundred six consecutive patients who underwent blood stem cell transplantation at the University of Rochester from 01/01/99 to 12/31/99 were examined retrospectively for the number of days to reach an absolute neutrophil count of 500 or 1000 cells/microl and an absolute platelet count of 20,000 or 50,000 cells/microl without transfusion support as measures of engraftment. Linear regression analyses were conducted to determine factors influencing engraftment. The number of CD34+ cells/kg and CFU-GM/kg correlated highly with the number of nucleated blood cells/kg. In this population, in which 90% of patients received >2 x 10(6) CD34+ cells/kg, neither the number of CD34+ cells/kg nor the number of CFU-GM/kg correlated with the time to engraftment as judged by neutrophil or platelet levels. In contrast, the lower the ratio of CFU-GM to CD34+ cells, the more rapid the reconstitution of platelets to 20,000/microl (P = 0.03) and 50,000/microl (P = 0.02). Thus, a lower ratio of the CFU-GM/CD34+ appended to reflect a greater number of hematopoietic reconstituting cells in the blood cell collection. The CFU-GM/CD34+ ratio is an apparent predictor of earlier platelet engraftment, suggesting that the ratio reflects the engraftment potential of mobilized donor progenitor cells.

Response of human CD34+ cells to CXC, CC, and CX3C chemokines: implications for cell migration and activation

Ultrastructural studies of marrow and examination of the in vivo processes of stem cell homing and mobilization show that multipotential hematopoietic progenitors are able to traverse endothelial cells. The regulation of this process by various classes of chemokines was studied in this report, using an in vitro model of transendothelial migration. Human umbilical vein endothelial cells (HUVECs) or bone marrow-derived endothelial cells (BMECs) were grown to confluence on 3-microm microporous membrane inserts and placed in 24-well culture plates. CD34(+) cells isolated from normal volunteer donor marrow by immunoadsorption or magnetic bead selection techniques were added to the inserts and various individual chemokines were added to the lower chamber of the culture plates in serum-free conditions. After 24 h, the percentage of transmigrated cells was determined. A mean of 8.5% of unfractionated marrow CD34(+) populations migrated, and all chemokines tested, with the exception of macrophage inflammatory protein-1alpha (MIP-1alpha), had some positive effect on this migration. The greatest effects were seen with stroma-derived factor-1alpha (SDF-1alpha) and stroma-derived factor-1beta (SDF-1beta), with lesser effects noted for other chemokines and cytokines. When the CD34(+) population was subselected for expression of CD38, a greater fraction of the CD38(-) cells migrated as compared to the CD38(+) fraction. CD34(+) cells isolated from mobilized peripheral blood and cord blood also migrated in response to chemokines. Chemokines of the CC, CXC, and CX(3)C classes as well as other hematopoietic cytokines may modulate the process of stem cell transmigration of endothelial cells. Further understanding of this process may help elucidate the mechanism of stem cell mobilization and homing.

Flavopiridol induces apoptosis and caspase-3 activation of a newly characterized Burkitt's lymphoma cell line containing mutant p53 genes

Burkitt's lymphoma cell lines have been important in vitro models for studying the pathogenesis of Burkitt's lymphoma (BL) and for exploring new treatment strategies. A new EBV(-) Burkitt's lymphoma cell line (GA-10) was established from a patient with a clinically aggressive, chemorefractory BL and characterized. Although functional p-glycoprotein could not be demonstrated by dye-efflux assays, both p53 genes were mutated in the GA-10 cells, perhaps contributing to the resistant phenotype of the original neoplasm. Two properties of BL cells which may be useful targets for novel cytotoxic therapeutics are their surface expression of CD77, the receptor for Shiga toxin (Stx), and their high rate of proliferation. Expression of CD77 on the GA-10 cells was heterogeneous in that certain subclones expressed high levels of CD77 and correspondingly exhibited strong growth inhibition by Stx while others showed low levels of CD77 expression and weak Stx-induced growth inhibition. Flavopiridol, a potent inhibitor of cell cycle progression through G1 and G2, induced cytotoxicity of the GA-10 cells with an LC(50) of approximately 40 nM vs 70 nM for HL-60 cells (P < 0.05). The concentrations of flavopiridol at which only 10% of the cells were viable (LC(10)) were approximately 280 nM for the GA-10 cells and 520 nM for the HL-60 cells (P < 0.05). Dose-related induction of apoptosis in response to flavopiridol was demonstrated in the GA-10 cells by morphology, TUNEL assay, and activation of caspase-3. Flavopiridol was also cytotoxic to seven other BL cell lines tested. These data suggest that flavopiridol may have therapeutic value in the treatment of Burkitt's lymphoma.

MIP-1alpha and TGF-beta production in CD34+ progenitor-stromal cell coculture systems: effects of progenitor isolation method and cell-cell contact

ABSTRACT Macrophage inflammatory protein-1alpha (MIP-1alpha) is a C-C chemokine which has antiproliferative effects on early hematopoietic progenitors and stimulatory effects on later progenitors. It also possesses chemotactic and activating properties for monocytes, macrophages, and T-cells. CD34+ progenitors isolated utilizing an avidin-biotin immunoadsorption column produced significant amounts of MIP-1alpha from 24 h onward when cultured in medium with 10% fetal calf serum (>200 pg/ml). Such production persisted through 96 h of culture and was greater when such progenitors were cocultured with a preformed marrow stromal layer (4000 pg/ml at 24 h). The production of MIP-1alpha declined over time of coculture with stromal layers, and stromal layers themselves produced minimal MIP-1alpha as detected by ELISA: <100 pg/ml. In contrast, CD34+ cells isolated by flow cytometry or by magnetic bead adsorption produced minimal MIP-1alpha (0-30 pg/ml). MIP-1alpha production also increased when cells isolated by these two methods were cocultured with stromal layers. The difference in MIP-1alpha production could not be accounted for by differences in purity of the CD34+ population between isolation methods nor on the basis of monocytic or lymphocytic contamination as assessed by the presence of CD14 or CD3 positive cells. CD34+ cells isolated by immune adsorption had increased expression of endothelial and mesenchymal associated antigens, however, suggesting that this subpopulation might account for the MIP-1alpha production observed. Freshly isolated CD34+ cells expressed MIP-1alpha message as assessed by RT-PCR and by in situ hybridization. Coculture of CD34+ cells isolated by any means with stromal cells increased transforming growth factor-beta (TGF-beta) production, in this case by the stromal layer itself. Both MIP-1alpha and TGF-beta have been found to influence cell cycle status and proliferation status of early hematopoietic progenitors, and both have potential effects on accessory cell function. These studies indicate that progenitor-stromal cell interactions may influence local cytokine output, thus potentially influencing progenitor cycling status and accessory cell activation. The method of isolation of CD34+ progenitors may influence secretion of certain cytokines and chemokines.

Mobilization of peripheral-blood stem cells by concurrent administration of daniplestim and granulocyte colony-stimulating factor in patients with breast cancer or lymphoma

PURPOSE

To evaluate the safety and hematopoietic activity of daniplestim administered concurrently with granulocyte colony-stimulating factor (G-CSF) for peripheral-blood stem-cell (PBSC) mobilization.

PATIENTS AND METHODS

In the initial dose-escalation phase, 25 patients with adenocarcinoma of the breast (AB; 13 patients) or lymphoma (12 patients) were given daniplestim at doses ranging from 0.1 to 3.75 microgram/kg/d plus G-CSF 10 microgram/kg/d. In the randomized phase, 52 patients with AB (27 patients) or lymphoma (25 patients) were randomized within disease categories to the daniplestim dose chosen in the dose-escalation phase plus G-CSF 10 microgram/kg/d (D+G) or placebo plus G-CSF 10 microgram/kg/d (P+G) for up to 7 days.

RESULTS

A daniplestim dose of 2. 5 microg/kg/d was chosen for further study because it was hematopoietically active and had an acceptable side-effect profile. In the randomized phase, in patients with AB, D+G was associated with a higher probability (P =.0696) of collecting >/= 2.5 x 10(6) CD34(+) cells/kg and significantly higher circulating CD34(+) cell counts (P =.0498) on days 6 through 9 after the initiation of dosing. The target level was more likely to be reached with additional leukaphereses in the patients given D+G. Patients given P+G did not benefit from additional leukaphereses beyond the first procedure. The type of mobilization did show a trend toward a shorter duration of neutropenia in the D+G group. The adverse events with D+G consisted largely of mild to moderate flu-like symptoms, including headache and fever, and occurred more frequently than with P+G.

CONCLUSION

Daniplestim administered at 2.5 microgram/kg/d is tolerable and active when combined with G-CSF, and the combination may prove more effective than G-CSF alone in promoting the collection of adequate numbers of CD34(+) cells for PBSC infusion in patients with AB.

Allogeneic bone marrow transplantation for children with acute leukemia: cytoreduction with fractionated total body irradiation, high-dose etoposide and cyclophosphamide

Marrow-ablative chemo-radiotherapy followed by hematopoietic stem cell rescue from an allogeneic source improves outcomes for children with high-risk acute leukemia. The first effective pre-transplant preparative regimens consisted of high-dose cyclophosphamide (CY) and total body irradiation (TBI). Subsequent attempts have been made to improve leukemia-free survival, by adding other chemotherapy agents to these agents. In previous clinical studies of total body irradiation, etoposide, cyclophosphamide (TBI-VP-16-Cy) in adult allogeneic bone marrow transplantation, there has been a high incidence of severe regimen-related toxicity. In this study, we investigated the safety and efficacy of this combination in 41 children who received TBI (12-14 Gy), VP-16 (30 mg/kg), and CY (60 mg/kg x 2) and then either matched sibling or alternative donor transplants for acute leukemia. There was only one case of fatal regimen-related toxicity. The estimated 3-year event-free survival for patients with early or intermediate stage disease was 68% (53-88%). The estimated event-free survival of patients with advanced disease was 17% (5-59%). TBI-VP16-CY is safe in pediatric transplantation, and it has good efficacy for transplant recipients with less advanced disease. Bone Marrow Transplantation (2000) 25, 489-494.

Treatment of chronic myelogenous leukemia with autologous bone marrow transplantation followed by roquinimex

Unmanipulated autologous bone marrow transplant (ABMT) offers patients with chronic myelogenous leukemia (CML) a long-term survival of 10%, at best. Immunotherapy has a role in the myeloid leukemias, and there is increasing evidence that of all hematopoietic neoplasms, CML may be the most susceptible to immune regulation. Roquinimex is known to enhance T cell, NK cell and macrophage activity. A phase II study was initiated in March 1992 to evaluate the role of roquinimex in Ph chromosome-positive CML post ABMT. Patients were conditioned with busulfan/ cyclophosphamide followed by reinfusion of unmanipulated Ph-positive bone marrow stem cells (>1 x 108 NBC/kg). When engraftment of neutrophils (ANC) reached 100/microl, patients received oral roquinimex twice weekly, escalating to a maximal dose of 0.2 mg/kg in 2 weeks. Seventeen patients have entered the study; 11 in first chronic phase (CP1); two in second chronic phase (CP2) and four in accelerated phase (AP). All required significant myelosuppressive therapy prior to ABMT to maintain stable blood counts and most had also received prior interferon therapy. All patients survived the transplant. Subsequent toxicity consisted mainly of musculoskeletal aches and peripheral edema. Additionally, specific skin changes were observed including graft-versus-host-like disease and eccrine sweat gland necrosis. Eight out of 17 patients are alive 28-60 months post ABMT. Of the nine patients who died, two were in CP2 and three in AP. All patients in CP1 went into a complete hematological remission post ABMT and seven of the 11 patients had at least a major cytogenetic response (greater than 65% Ph-negative metaphases) at 1 year or beyond and four of the 11 patients had a complete cytogenetic response at 2 years or beyond. Cytogenetic response post transplant often developed over time and did not simply represent post ABMT engraftment with Ph-negative cells. The clinical and cytogenetic data in these patients are encouraging and suggest that roquinimex may have significant activity when given post ABMT to patients with Ph-positive CML.

Analysis of factors that correlate with mucositis in recipients of autologous and allogeneic stem-cell transplants

PURPOSE

To identify predictors of oral mucositis and gastrointestinal toxicity after high-dose therapy.

PATIENTS AND METHODS

Mucositis and gastrointestinal toxicity were prospectively evaluated in 202 recipients of high-dose therapy and autologous or allogeneic stem-cell rescue. Of 10 outcome variables, three were selected as end points: the peak value for the University of Nebraska Oral Assessment Score (MUCPEAK), the duration of parenteral nutritional support, and the peak daily output of diarrhea. Potential covariates included patient age, sex, diagnosis, treatment protocol, transplantation type, stem-cell source, and rate of neutrophil recovery. The three selected end points were also examined for correlation with blood infections and transplant-related mortality.

RESULTS

A diagnosis of leukemia, use of total body irradiation, allogeneic transplantation, and delayed neutrophil recovery were associated with increased oral mucositis and longer parenteral nutritional support. No factors were associated with diarrhea. Also, moderate to severe oral mucositis (MUCPEAK > or = 18 on a scale of 8 to 24) was correlated with blood infections and transplant-related mortality: 60% of patients with MUCPEAK > or = 18 had positive blood cultures versus 30% of patients with MUCPEAK less than 18 (P =.001); 24% of patients with MUCPEAK > or = 8 died during the transplantation procedure versus 4% of patients with MUCPEAK less than 18 (P =.001).

CONCLUSION

Gastrointestinal toxicity is a major cause of transplant-related morbidity and mortality, emphasizing the need for corrective strategies. The peak oral mucositis score and the duration of parenteral nutritional support are useful indices of gastrointestinal toxicity because these end points are correlated with clinically significant events, including blood infections and treatment-related mortality.

Human immunodeficiency virus and the hematopoietic repertoire: implications for gene therapy

The human immunodeficiency virus (HIV) infects primarily the hematopoietic and immune systems. At the onset of infection, an initial activation of the immune system occurs, with a subsequent suppression thereafter due to direct viral infection of cells, inhibitory effects of HIV proteins, an altered microenvironment with cytokine imbalance, and increased apoptosis of both infected and non-infected cells. The CD34+ hematopoietic stem cell, however, remains free of infection. Novel methods in gene therapy utilize viral vectors that can introduce genes with good efficiency into the non-dividing stem cell. Therefore, HIV-resistance genes can be introduced into stem cells using these vectors. This confers resistance to infection to their respective progeny, and concurrently allows for repopulation of the immuno-hematopoietic repertoire. Applications of this technology to the patient infected with HIV are discussed in the context of myeloablative therapy and stem cell rescue.

A RANTES-antibody fusion protein retains antigen specificity and chemokine function

The successful eradication of cancer cells in the setting of minimal residual disease may require targeting of metastatic tumor deposits that evade the immune system. We combined the targeting flexibility and specificity of mAbs with the immune effector function of the chemokine RANTES to target established tumor deposits. We describe the construction of an Ab fusion molecule with variable domains directed against the tumor-associated Ag HER2/neu, linked to sequences encoding the chemokine RANTES (RANTES.her2.IgG3). RANTES is a potent chemoattractant of T cells, NK cells, monocytes, and dendritic cells, and expression of RANTES has been shown to enhance immune responses against tumors in murine models. RANTES.her2.IgG3 fusion protein bound specifically to HER2/neu Ag expressed on EL4 cells and on SKBR3 breast cancer cells as assayed by flow cytometry. RANTES.her2.IgG3 could elicit actin polymerization of THP-1 cells and transendothelial migration of primary T lymphocytes. RANTES.her2.IgG3 prebound to SKBR3 cells also facilitated migration of T cells. RANTES.her2.IgG3 bound specifically to the CCR5 chemokine receptor, as demonstrated by flow cytometry, and inhibited HIV-1 infection via the CCR5 coreceptor. RANTES.her2.IgG3, alone or in combination with other chemokine or cytokine fusion Abs, may be a suitable reagent for recruitment and activation of an expanded repertoire of effector cells to tumor deposits.

Autotransplantation for relapsed or refractory Hodgkin's disease: long-term follow-up and analysis of prognostic factors

Seventy consecutive patients with refractory or relapsed Hodgkin's disease who received high-dose chemotherapy followed by autologous stem cell rescue were analyzed to identify clinically relevant predictors of long-term event-free survival. High-dose therapy consisted primarily of carmustine (BCNU), etoposide, cytarabine and cyclophosphamide (BEAC). The 5-year Kaplan-Meier event-free survival (EFS) for the entire cohort was 32% (95% confidence interval; 18-45%) with a median follow-up of 3.6 years (range 7 months-7.6 years). The most significant predictor of improved survival was the presence of minimal disease (defined as all areas < or =2 cm) at the time of transplant: the 5 years EFS was 46 vs 10% for patients with bulky disease (P = 0.0002). Other independent predictors identified by step-wise regression analysis included the presence of non-refractory disease and the administration of post-transplant involved-field radiotherapy (XRT). Treatment-related mortality occurred in 13 of 70 patients: nine patients (13%) died within the first 100 days, mainly from cardiopulmonary toxicity. However, only one of 24 patients (4%) transplanted during the last 4.5 years died from early treatment-related complications. While high-dose therapy followed by autotransplantation led to long-term EFS of 50% for patients with favorable prognostic factors, a substantial proportion of patients relapsed, indicating that new therapeutic strategies are needed.

Effect of stromal cell coculture on progenitor cell expansion and myeloid effector function in vitro

Stimulation of CD34(+)-enriched marrow or light density marrow with various growth factor combinations can generate granulocyte progenitors and mature neutrophils in vitro. In this work, we have examined the influence of irradiated marrow stromal layers on growth factor-induced myeloid and early multipotential progenitor expansion from enriched marrow CD34+ progenitors. We have also explored whether the addition of early-acting growth factors known to enhance myelopoiesis in long-term culture, such as fibroblast growth factor (b-FGF), insulin growth factor (IGF-1), c-kit ligand or stem cell factor (SCF), and flk-2flt-3 ligand (FL), can lengthen survival of CD34+ progenitors in these cultures. Stromal cell coculture resulted in greater numbers of total cells and CFU-GM at day 7 and day 14, but with the addition of multiple growth factors, these effects of stromal cell coculture were diminished. At day 14, generally < 1% of the expanded cells over stromal coculture conditions were CD34+, with up to 90% demonstrating CD15 positivity. Culture of CD34+ cells in the presence of early-acting growth factors did not cause significant expansion of CD34+ cells over a 14-day life span, even in the presence of marrow stromal cells. These data suggest that although stromal cell coculture for a period up to 14 days can enhance expansion of total cell numbers and CFU-GMs, stromal cell presence does not lead to expansion of CD34+ cells in these cultures and may diminish the number of clonogenic cells present when growth factors with differentiating capacity are present. Mature neutrophils harvested from such cultures are capable of chemotaxis, actin polymerization, and migration, suggesting a replete functional status.

TGF-beta down-regulates stromal IL-7 secretion and inhibits proliferation of human B cell precursors

Development of lymphoid progenitors in vivo requires interaction with a bone marrow stromal microenvironment containing multiple cytokines involved in the development of nonlymphoid hemopoietic lineages. We tested the effect of one such cytokine, TGF-beta, on the proliferation of early human clonogenic lymphoid progenitors using a stroma-dependent in vitro culture system. TGF-beta caused a dose-dependent inhibition of lymphoid progenitor colonies that was reversible at low TGF-beta doses by addition of exogenous IL-7 to the cultures. IL-7 was unable to reverse the inhibitory effect of higher TGF-beta concentrations or inhibition caused by IL-1alpha, IL-4, or TNF-alpha. Stromal IL-7 mRNA expression and protein secretion were markedly down-regulated by TGF-beta, suggesting that inhibition of stromal IL-7 secretion partially accounts for the inhibitory effect of TGF-beta on lymphopoiesis in this culture system. It is likely that higher TGF-beta concentrations do not inhibit lymphopoiesis by down-regulating IL-7 receptor expression, since this cytokine did not reduce IL-7R alpha or gamma c mRNA levels in normal B cell precursors. Since direct stromal contact is required for in vitro lymphopoiesis, the potential regulation of the IL-7 pathway by cell adhesion was examined. Adhesion of human B cell precursors to stroma did not alter stromal IL-7 expression or expression of IL-7R alpha or gamma c-chains by B cell precursors. These results indicate that TGF-beta is a significant negative regulator of stroma-dependent proliferation of early human lymphoid progenitors and acts in part by down-regulating stromal IL-7 secretion.

TGF-beta down-regulates stromal IL-7 secretion and inhibits proliferation of human B cell precursors

Development of lymphoid progenitors in vivo requires interaction with a bone marrow stromal microenvironment containing multiple cytokines involved in the development of nonlymphoid hemopoietic lineages. We tested the effect of one such cytokine, TGF-beta, on the proliferation of early human clonogenic lymphoid progenitors using a stroma-dependent in vitro culture system. TGF-beta caused a dose-dependent inhibition of lymphoid progenitor colonies that was reversible at low TGF-beta doses by addition of exogenous IL-7 to the cultures. IL-7 was unable to reverse the inhibitory effect of higher TGF-beta concentrations or inhibition caused by IL-1alpha, IL-4, or TNF-alpha. Stromal IL-7 mRNA expression and protein secretion were markedly down-regulated by TGF-beta, suggesting that inhibition of stromal IL-7 secretion partially accounts for the inhibitory effect of TGF-beta on lymphopoiesis in this culture system. It is likely that higher TGF-beta concentrations do not inhibit lymphopoiesis by down-regulating IL-7 receptor expression, since this cytokine did not reduce IL-7R alpha or gamma c mRNA levels in normal B cell precursors. Since direct stromal contact is required for in vitro lymphopoiesis, the potential regulation of the IL-7 pathway by cell adhesion was examined. Adhesion of human B cell precursors to stroma did not alter stromal IL-7 expression or expression of IL-7R alpha or gamma c-chains by B cell precursors. These results indicate that TGF-beta is a significant negative regulator of stroma-dependent proliferation of early human lymphoid progenitors and acts in part by down-regulating stromal IL-7 secretion.

Autotransplantation for relapsed or refractory non-Hodgkin's lymphoma (NHL): long-term follow-up and analysis of prognostic factors

One hundred and thirty-six patients autografted for relapsed or refractory non-Hodgkin's lymphoma (NHL) were evaluated to assess long-term event-free survival and to identify important prognostic factors. High-dose therapy consisted primarily of carmustine (BCNU), etoposide, cytarabine, and cyclophosphamide (BEAC) followed by unpurged autologous stem cell rescue. The 5-year Kaplan-Meier event-free survival (EFS) for the entire cohort was 34% (95% confidence interval: 24-44%) with a median follow-up of approximately 3 years (range 0-7.5 years). For patients entering with minimal disease (defined as all areas < or = 2 cm), the 5-year EFS was 40 vs 26% for those entering with bulky disease (P = 0.0004). In the multivariate analysis, minimal disease on entry and administration of involved-field XRT post-transplant were significantly associated with improved EFS; the latter association was observed mainly in the cohort of patients with bulky disease. The overall 100-day treatment-related mortality rate was 4.4% (3% for the last 71 patients). New strategies are needed to reduce the high rate of relapse (50-60%) following auto-transplantation for relapsed or refractory NHL.

Successful treatment of a generalized human papillomavirus infection with granulocyte-macrophage colony-stimulating factor and interferon gamma immunotherapy in a patient with a primary immunodeficiency and cyclic neutropenia

BACKGROUND

We describe a patient with generalized verrucosis secondary to human papillomavirus (HPV) type 2 infection and a primary immunodeficiency and cyclic neutropenia. Treatment, which was well tolerated, included granulocyte-macrophage colony-stimulating factor and interferon gamma (IFN-gamma). In vitro assays to assess responses of T lymphocytes to mitogens (ie, proliferation assay and IFN-gamma enzyme-linked immunosorbent assay) were performed. In situ hybridization and polymerase chain reaction were used to detect HPV DNA in skin biopsy specimens.

OBSERVATIONS

The T lymphocytes of the patient showed a significant (P < .05, unpaired Student t test) defect in IFN-gamma production (the basis for initiating IFN-gamma therapy). The response to immunotherapy was confirmed by using molecular methods. Six months after the completion of immunotherapy, HPV DNA was undetectable in skin samples from clinically regressed warts (according to the results of in situ hybridization and polymerase chain reaction).

CONCLUSIONS

Our patient had treatment-resistant generalized verrucosis for 13 years. Treatment with granulocyte-macrophage colony-stimulating factor and IFN-gamma may have reconstituted an immune response against HPV, resulting in the dramatic regression of her widespread warts.

Expression of interleukin-7 receptor by lineage-negative human bone marrow progenitors with enhanced lymphoid proliferative potential and B-lineage differentiation capacity

Relatively little is known about the relationship of lymphoid-associated gene expression to the proliferation and differentiation potential of early human bone marrow lymphoid progenitors. Surface expression of interleukin-7 (IL-7) receptor-alpha (IL-7R alpha), a component of the high-affinity receptor for the lymphoid precursor growth factor IL-7, defined a CD34+ progenitor subset lacking the CD19+ pro-B phenotype but demonstrating markedly enhanced lymphoid clonogenic capacity and the ability to differentiate into pro-B cells in short-term culture. These progenitors expressed mRNA for the lymphoid-associated genes Ig beta, RAG-1, and PAX-5, and were uniformly TdT-positive (TdT+). In contrast, IL-7R alpha-/CD19-/ CD34+ progenitors had a 50-fold reduced lymphoid clonogenic capacity and did not differentiate into pro-B cells in short-term culture. Expression of TdT and the lymphoid-associated genes Ig beta and RAG-1, but not PAX-5, was detected in this fraction, although at lower levels than in the IL-7R alpha+ progenitors. In contrast to IL-7R alpha, loss of the stem cell factor receptor c-kit was associated with enhanced lymphoid clonogenic potential and increased B-lineage differentiation potential. These results indicate that IL-7R alpha expression defines entry into a developmental stage characterized by upregulation of multiple lymphoid-associated genes and enhanced fitness for B-lymphoid differentiation. The onset of IL-7R alpha and PAX-5 expression immediately before acquisition of CD19 is consistent with evidence suggesting upregulation of CD19 through pathways involving PAX-5 and IL-7.

Expression of costimulatory molecules: B7 and ICAM up-regulation after treatment with a suicide gene

The herpes simplex virus thymidine kinase gene (HSV-TK) in combination with ganciclovir (GCV), is currently being used in gene therapy-based clinical trials for cancer treatment. Its therapeutic effect is based on a "bystander effect" whereby HSV-TK gene-modified tumor cells are toxic to nearby unmodified tumor cells when exposed to the antiviral drug GCV. We have recently hypothesized that the in vivo mechanism of this bystander effect is due to alterations in the tumor microenvironment in response to release of cytokines and an infiltration of leukocytes after treatment with HSV-TK gene-modified tumor cells and GCV, which results in tumor regression. Expression of B7, a recently identified costimulatory molecule that is important for T-cell stimulation, has been shown to be modulated by stimulatory cytokines interferon-gamma, tumor necrosis factor-alpha, and inhibited by interleukin-10. In the present study, we investigated whether the cytokines released after HSV-TK and GCV treatment could include the expression of the costimulatory molecules B7-1 and B7-2 and the adhesion molecule (ICAM)-1 in the tumor. Furthermore, we investigated whether this altered environment affected the antitumor properties of host lymphocytes. An in vitro model was developed to establish the effects of HSV-TK gene-modified tumor cells and GCV on tumor infiltrating cells. The murine macrophage cell line (IC21) was exposed to either supernatants or cell lysates collected from a mixture of HSV-TK-transduced (KBALB-STK) and non-transduced (KBALB) murine fibrosarcoma tumor cells previously exposed to GCV (experimental). Immunohistochemical analysis showed a significant expression (P < .0001) of B7-1 and B7-2 post exposure of IC21 cells to either supernatant or lysate. In contrast, the level of expression in IC21 cells exposed to the control lysate or supernatant remained unchanged for B7-1 and B7-2. In vivo analysis for B7-1 and B7-2 expression by immunohistochemistry in tumor tissues from experimental mice receiving HSV-TK gene-modified tumor cells and GCV treatment showed a significant expression of B7.1 (35%, P < .0001) and B7.2 (38.2%, P < .0001) on tumor-infiltrating mononuclear cells. In contrast, tumor-bearing control animals showed low levels of B7-2 expression (5.8%), whereas B7-1 was undetectable, as confirmed by reverse-transcriptase polymerase chain reaction. In addition, a significant up-regulation of ICAM expression (50%) on tumor tissues was observed in the experimental group (P = .0317) as compared with the control group (25%). Furthermore, T cells isolated from experimental mice showed a significant in vitro proliferative response (p = .0202) when exposed to syngeneic tumor cells as compared with the control group. These data demonstrated that the use of HSV-TK gene-modified tumor cells and GCV as a suicide gene in the treatment of an intraperitoneal tumor resulted in the expression of the B7 costimulatory molecules and ICAM-1 adhesion molecule and enhanced proliferative response of host T cells. These findings help to understand the mechanism of tumor cell killing in vivo using HSV-TK gene-modified tumor cells.

Flutamide-induced cyanosis refractory to methylene blue therapy

Flutamide, an anti-androgen used in prostate cancer therapy, is also a derivative of aniline. Mild, usually asymptomatic, methaemoglobinaemia has been reported. We report a patient receiving flutamide therapy who developed cyanosis, dyspnoea and anaemia, initially attributed to marked methaemoglobinaemia by the CO-Oximeter method. An unsuccessful trial of methylene blue therapy led to the finding of marked sulphaemoglobinaemia. Sulphaemoglobinaemia has not previously been reported with flutamide use. Recognition of this association is important, given the refractoriness of sulphaemoglobinaemia to methylene blue therapy.

Stem cell factor and stromal cell co-culture prevent apoptosis in a subculture of the megakaryoblastic cell line, UT-7

The megakaryoblastic cell line, UT-7, is dependent for its growth upon interleukin-3 (IL-3), erythropoietin, or granulocyte-macrophage colony stimulating factor (GM-CSF). A subculture of this line can be maintained in recombinant human c-kit ligand [stem cell factor (SCF)] at 100 ng/ml without requirement for other growth factors. Removal of this subculture from SCF results in rapid loss of viability and decreased proliferation. Cells grown in SCF also can be maintained in GM-CSF but not vice versa. In this work, we have characterized the SCF dependence of this UT-7 subculture. Stem cell factor removal results in apoptosis and a decline in viability which can be restored partially by re-addition of SCF, GM-CSF, or co-culture with adherent marrow stromal cells. Apoptosis in the factor-starved UT-7 population has been documented by light microscopy, electron microscopy and DNA analysis, showing the typical 180 base pair laddering characteristic of apoptosis. To quantitate the degree of apoptosis in the cell populations, and to assess whether apoptosis decreased with re-exposure of starved cells to growth factors or stroma, we utilized flow cytometry. This confirmed that exposure of previously factor-starved cells to stroma decreased the percentage of cells undergoing apoptosis. Co-culture with an SCF-deficient murine stromal cell line was also able to prevent apoptosis, suggesting contribution of other stromal cell factors. Experiments performed using trans-well inserts which do not allow cell passage, showed greatest viability of cells in contact with stroma, but viability was also improved in cells cultured in the presence of, but not in contact with, stromal cells compared to those cultured above plastic, suggesting a role for soluble stroma-produced substances. These data demonstrate that SCF alone can prevent apoptosis in cells dependent upon its presence for proliferation. Also, marrow stromal cells can serve as a partial substitute for growth factor in the prevention of apoptosis in these cells, probably due to constitutive presentation of SCF and other hematopoietic growth factors in both soluble and surface-bound forms.

In vivo analysis of the 'bystander effect': a cytokine cascade

The "bystander effect" refers to the death of unmodified tumor cells when in contact with ganciclovir (GCV)-exposed, herpes simplex virus-thymidine kinase (HSV-TK)-modified tumor cells. Although the exact mechanism or mechanisms involved in mediating the bystander effect in vivo are unknown, our findings suggest that an intact host immune system is required for the phenomenon to occur. The present study was designed to establish the effect of HSV-TK-modified tumor cells and GCV on the tumor and its microenvironment in vivo. In sublethally irradiated and immunodeficient Balb/c mice, the bystander effect was observed to be diminished or abrogated. Histopathologic examination of the tumor mass from immunocompetent mice demonstrated centralized hemorrhagic tumor necrosis (38%) after inoculation of the HSV-TK-modified tumor cells and GCV in tumor-bearing mice compared with the control mice (5%), indicating that cytokines such as tumor necrosis factor-alpha (TNF-alpha) were being released locally. This hypothesis was underscored using reverse transcriptase polymerase chain reaction (RT-PCR), by the demonstration of cytokine mRNA expression in mice treated with HSV-TK-expressing tumors and GCV. Semiquantitative PCR analysis for TNF-alpha using PCR-MIMIC on tumor samples from mice treated on days 1 and 4 showed a two-fold increase in the level on mRNA expression. Also, immunohistochemical staining for TNF-alpha showed that mononuclear inflammatory cells infiltrating the tumor were its source. Finally, characterization of tumor-infiltrating lymphocytes (TIL) in experimental animals demonstrated a two- to three-fold increase in the number of macrophages and T cells compared with control animals. These results demonstrate that, in vivo, the bystander effect is mediated in part by an antitumor response through the release of cytokines. Further, the cytokine milieu and tumor microenvironment can be modulated following injection of HSV-TK cells and GCV to enhance the host immune response, which is of potential use in clinical trials.

In situ use of suicide genes for cancer therapy

Gene therapy has now become a standard experimental approach for treating cancers that have failed conventional therapies. As the understanding of the molecular nature of carcinogenesis develops, new approaches are being taken to directly target tumor cells, thus bypassing the difficulties of killing cells that are resistant to chemotherapy and radiation. One emerging gene therapy approach has been through the genetic modification of tumor cells with a suicide gene such as the herpes simplex virus thymidine kinase gene (HSV-TK) and ganciclovir (GCV) therapy. Death of tumor cells modified with the HSV-TK gene leads to killing of unmodified in situ tumor cells in a phenomenon termed the "bystander effect." The basis both for this effect and other gene therapy trials underway for the treatment of cancer will be discussed.

Patients > or = age 40 years undergoing autologous or allogeneic BMT have regimen-related mortality rates and event-free survivals comparable to patients < age 40 years

To evaluate the safety and efficacy of marrow transplantation for older adults, the regimen-related mortality and event-free survival for patients > or = 40 years were compared with those for patients < 40 years. Of 148 consecutive patients receiving autotransplants for lymphoma or Hodgkin's disease, 70 were < 40 years and 78 were > or = 40 years at the time of transplant, including 40 who were > or = 50 years and 12 who were > or = 60 years. Eleven patients (16%) in the younger age group died from transplant-related complications compared with 4 (5%) in the older age group. The 4-year actuarial event-free survivals (EFS) for the younger and older age groups were 43% and 48%, respectively. After adjustment for covariates with prognostic significance, older age was marginally associated with improved event-free survival (P = 0.08). Of 92 consecutive patients undergoing allogeneic BMT during the same period, 62 patients were < 40 years and 30 patients were > or = 40 years, including 8 patients > or = 50 years, and 1 patient > 60 years. Non-relapse mortality (including deaths from GVHD) occurred in 28 of the younger patients (45%) and 9 of the older patients (30%). The 3-year actuarial EFS for the younger patients was 26% vs. 56% for the patients > or = 40 years (P = 0.057). However, this difference was mainly due to the higher proportion of patients with CML and early-stage leukemia in the older age group.(ABSTRACT TRUNCATED AT 250 WORDS)

Gene-modified cells for the treatment of cancer

Gene therapy involves the insertion of a gene into an organism to treat a disease. Since its early development in the 1970s, gene therapy has expanded rapidly both in terms of the methods available and the number of candidate diseases for treatment. This report reviews gene therapy for cancer, including methodology, pre-clinical studies and experimental clinical trials.

Effect of stem cell factor on myelopoiesis potential in human Dexter-type culture systems

Hematopoiesis is influenced by the presence of the hematopoietic microenvironment, and Dexter-type liquid culture systems represent an in vitro representation of some aspects of the microenvironment that are optimal for the propagation of myeloid progenitors. Marrow stromal layers, which constitute part of these culture systems, produce growth factors, including stem cell factor (SCF), a ligand for the c-kit proto-oncogene that has been found to increase detection of myeloid, erythroid, and megakaryocytic progenitors in short-term marrow colony assays. In this work, the role of SCF in Dexter-type culture systems was examined to better define its contribution to steady-state myelopoiesis. When cultured in the continued presence of 100 ng/mL SCF, both primary and recharged cultures demonstrated significantly greater CFU-GM output, with quantitative differences noted throughout culture duration (up to 6 weeks). This increase in CFU-GM could be inhibited specifically with the addition of 1:1500 SR-1, a neutralizing anti-c-kit monoclonal antibody (MAb) that neutralizes the biological effects of SCF, and the increase was noted both with recharged light-density marrow cells and purified CD34+ progenitor cells. On the other hand, when primary or recharged marrow cultures were established in the absence of exogenous SCF, but in the continuous presence of SR-1, no inhibition of CFU-GM output was observed. When light-density marrow cells were purged of pre-existing CFU-GM by 4-hydroperoxycyclophosphamide (4-HC) and were seeded over irradiated stromal layers, exogenous SCF resulted in detection of CFU-GM from 4-HC-treated cells as early as 1 week of culture, as compared to the lack of significant emergence of CFU-GMs at 4 weeks in the control cultures. This SCF effect was also inhibited by SR-1. Purified CD34+ progenitor cells did not adhere to SCF immobilized to tissue culture plates, and the adhesion of such progenitors to murine Steel lines transfected with membrane-bound SCF was not greater than to the parent nontransfected Steel line, suggesting that the effect of SCF was not on CD34+ cell adhesion. These studies confirm the action of SCF at a pre-CFU level, and they demonstrate the ability of SCF to stimulate increased production of myeloid progenitors in long-term liquid culture systems.

Characterization of the adherence of normal and leukemic CD34+ cells to endothelial monolayers

The capacity of normal CD34+ marrow cells and CD34+ leukemic cell lines to adhere to human umbilical vein endothelial cells has been examined. Such interactions have importance since the processes of homing and egress within the marrow microenvironment involve the traverse of sinusoidal endothelium. Umbilical vein endothelial monolayers expressed CD44 and CD54 constitutively, and expression of both E-selectin (ELAM) and vascular cell adhesion molecule-1 (VCAM-1) were inducible with interleukin-1 (IL-1) alpha and beta and tumor necrosis factor (TNF). CD34+ marrow cells bound to unstimulated endothelial layers (33 vs. 16% to plastic), and their adhesion was significantly increased in the presence of IL-1 or TNF. This increased adhesion was not inhibited by functionally blocking antibodies to E-selectin or to CD54 but was partially inhibited by antibodies to VCAM. CD34+ KG1a cells also bound to endothelial monolayers (33 vs. 8% to plastic), and such adhesion was also upregulated by pretreatment of the endothelial cells with IL-1 or TNF. In contrast to normal CD34+ cells, this increased adhesion was inhibited by antibodies to E-selectin but not to VCAM. These findings indicate that adhesion of both normal CD34+ cells and leukemic blasts to endothelial cells can be upregulated by inflammatory mediators such as TNF and IL-1.

Mechanisms of cytopenia in human immunodeficiency virus infection

Human immunodeficiency virus (HIV) infection often has effects on the hematopoietic system which can be distinguished from the concurrent effects of medications or opportunistic infections. Exactly how the virus mediates these effects remains uncertain, but both in vivo and in vitro studies have pointed up possible direct and indirect modes of hematopoietic suppression. Whether a significant fraction of CD34+ cells in vivo are infected with HIV remains controversial, but most studies using in situ polymerase chain reaction techniques would suggest not. Other more indirect modes of hematopoietic cell suppression such as production of autoantibodies, production of other humoral inhibitory factors, T-cell mediated suppression of hematopoiesis, or production of inhibitory or stimulatory cytokines may also be contributory. It is probable that several of these mechanisms may occur simultaneously, and an increased understanding of their role may lead to improved strategies to correct the cytopenias which often accompany HIV disease.

CD34+ progenitor cell isolation from blood and marrow: a comparison of techniques for small-scale selection

The isolation and characterization of primitive hematopoietic cells and their purification in sufficient numbers is important in clinical and research marrow transplantation settings. As systems for large-scale isolation and amplification of such cells are developed, they may assume importance in transplantation, treatment of marrow failure and for gene therapy applications. Such cells have been isolated by numerous techniques and in this work, small-scale isolation of CD34+ cells by two immunoadsorption purification methods is compared with isolation by flow cytometry. While the immunoadsorption techniques allow for the processing of large numbers of density gradient-separated or unseparated cells for progenitor isolation, such techniques do not achieve the purity afforded by fluorescence activated cell sorter separation.

Effects of GM-CSF on Ki67 expression and cell cycle traverse in acute myelogenous leukemia specimens and cell lines

A new strategy in the treatment of acute myelogenous leukemia is to attempt to increase the growth fraction of clonal leukemic cells prior to administration of chemotherapeutic agents by the administration of hematopoietic growth factors. We have studied the effect of GM-CSF on the cell cycle status and Ki67 nuclear antigen expression of AML blasts in vitro. The effect of growth factors and stromal cell co-culture on Ki67 expression in leukemic cell lines was also examined. Neither stromal cell co-culture nor exposure of factor-dependent and factor-independent cell lines to GM-CSF, IL-3, SCF, or combinations thereof significantly changed the percentage of cells expressing Ki67. In the AML population analyzed as a whole, exposure of blasts to GM-CSF for up to 96 h did not significantly change the percentage of cells in S phase or expressing Ki67.

Cytokine regulation of early human lymphopoiesis

An in vitro culture system in which bone marrow-derived fibroblast-like cells support the growth of TdT+ colonies derived from CD34+/CD10- human bone marrow progenitor cells has recently been described. The regulatory role of cytokines during early B lineage commitment was investigated using this culture system. Expression of IL-7, a cytokine that induces proliferation of B cell precursors, was detectable in the adherent layer by PCR and bioassay. Lymphoid progenitor colonies were inhibited by neutralizing anti-IL-7 Ab, suggesting that IL-7 produced by the adherent layer was required even in the earliest recognizable stages of human B cell lymphopoiesis. IL-1 alpha, IL-4, and TNF-alpha inhibited lymphoid progenitor colonies in a dose-dependent fashion. Neutralizing Ab to IL-1 alpha, IL-4, or TNF-alpha did not increase lymphoid progenitor colonies, suggesting that inhibitory concentrations of these cytokines are not constitutively elaborated in the adherent layer. Recombinant Steel factor and IL-6 as well as neutralizing Abs to these cytokines did not significantly affect lymphoid progenitor colonies, arguing against an important role for these cytokines in early human B lymphopoiesis. These results indicate that IL-7 provided by the bone marrow microenvironment is a critical growth factor at the earliest recognizable stages of human lymphopoiesis. IL-1 alpha, IL-4, and TNF-alpha have been shown to indirectly stimulate release of myeloid growth factors. The inhibition of lymphopoiesis by these cytokines suggests a possible mechanism for the observed reciprocal relationship between lymphoid and myeloid supportive bone marrow microenvironments.

Cytokine regulation of early human lymphopoiesis

An in vitro culture system in which bone marrow-derived fibroblast-like cells support the growth of TdT+ colonies derived from CD34+/CD10- human bone marrow progenitor cells has recently been described. The regulatory role of cytokines during early B lineage commitment was investigated using this culture system. Expression of IL-7, a cytokine that induces proliferation of B cell precursors, was detectable in the adherent layer by PCR and bioassay. Lymphoid progenitor colonies were inhibited by neutralizing anti-IL-7 Ab, suggesting that IL-7 produced by the adherent layer was required even in the earliest recognizable stages of human B cell lymphopoiesis. IL-1 alpha, IL-4, and TNF-alpha inhibited lymphoid progenitor colonies in a dose-dependent fashion. Neutralizing Ab to IL-1 alpha, IL-4, or TNF-alpha did not increase lymphoid progenitor colonies, suggesting that inhibitory concentrations of these cytokines are not constitutively elaborated in the adherent layer. Recombinant Steel factor and IL-6 as well as neutralizing Abs to these cytokines did not significantly affect lymphoid progenitor colonies, arguing against an important role for these cytokines in early human B lymphopoiesis. These results indicate that IL-7 provided by the bone marrow microenvironment is a critical growth factor at the earliest recognizable stages of human lymphopoiesis. IL-1 alpha, IL-4, and TNF-alpha have been shown to indirectly stimulate release of myeloid growth factors. The inhibition of lymphopoiesis by these cytokines suggests a possible mechanism for the observed reciprocal relationship between lymphoid and myeloid supportive bone marrow microenvironments.

Integrins and adhesive receptors in normal and leukemic CD34+ progenitor cells: potential regulatory checkpoints for cellular traffic

Multiple adhesion receptors are involved in the interaction of hematopoietic cells with the marrow microenvironment. This work characterizes the expression of various adhesive receptors on normal early hematopoietic precursors and reviews how they might be altered in leukemic states. Early hematopoietic CD34+ cells express CD18, CD11a, CD49d, CD49e, CD44, ICAM-1, and ICAM-3. Likewise, most AML samples express CD49d, CD49e, and CD44. In addition to mediating the adherence of progenitors to the marrow, these multiple receptors and their respective ligands may serve to regulate in vivo leukemic cell agrees from marrow and the ability of certain leukemic phenotypes to selectively seek extramedullary sanctuary sites such as the skin and the central nervous system.

One hundred autotransplants for relapsed or refractory Hodgkin's disease and lymphoma: value of pretransplant disease status for predicting outcome

PURPOSE

One hundred autotransplants for Hodgkin's disease (HD) or non-Hodgkin's lymphoma (NHL) were examined prospectively to identify variables with prognostic significance.

PATIENTS AND METHODS

Ninety-six patients with relapsed or refractory HD or NHL underwent 100 autotransplants. Patients received high-dose carmustine (BCNU), etoposide, cytarabine, and cyclophosphamide (BEAC) followed by unpurged autologous stem-cell rescue.

RESULTS

The 3-year actuarial event-free survival (EFS) rate for the 47 HD patients is 49%, with a median followup duration of 2 years. For the 53 NHL patients, the 3-year actuarial EFS rate is 40%, with a median follow-up duration of 19 months. By multivariate analysis, minimal disease on admission (all areas < or = 2 cm) is associated with improved EFS (HD, P = .003, NHL, P = .03). The projected EFS rate for HD patients entering with minimal disease is 70% versus 15% for patients with bulky disease (P = .0001). The projected EFS rate for NHL patients with minimal disease is 48% versus 25% for patients with bulky disease (P = .04). Posttransplant involved-field radiotherapy, administered to 26 of the last 61 patients, was associated with an improved EFS rate for NHL patients (P = .015). The BEAC regimen was well tolerated by patients who entered the study with minimal disease (mortality rate, < 5%), but caused significant toxicity in patients with bulky disease (mortality rate, 25%).

CONCLUSION

Disease burden before autotransplantation is an important predictor of regimen-related toxicity and EFS. Posttransplant involved-field radiotherapy may improve outcomes in select patients with NHL. The BEAC regimen is safe and effective, particularly for patients with minimal disease.

The "bystander effect": tumor regression when a fraction of the tumor mass is genetically modified

Tumor cells expressing the herpes simplex virus thymidine kinase (HSV-TK) gene are sensitive to the drug ganciclovir (GCV). We demonstrate here that HSV-TK-positive cells exposed to GCV were lethal to HSV-TK-negative cells as a result of a "bystander effect." HSV-TK-negative cells were killed in vitro when the population of cultured cells contained only 10% HSV-TK-positive cells. The mechanism of this "bystander effect" on HSV-TK-negative cells appeared to be related to the process of apoptotic cell death when HSV-TK-positive cells were exposed to GCV. Flow cytometric and electron microscopic analyses suggested that apoptotic vesicles generated from the dying gene-modified cells were phagocytized by nearby, unmodified tumor cells. Prevention of apoptotic vesicle transfer prevented the bystander effect. The toxic effect of HSV-TK-positive cells on HSV-TK-negative cells was reproduced in an in vivo model. A mixed population of tumor cells consisting of HSV-TK-positive and HSV-TK-negative cells was inoculated s.c. into mice. Regression of the tumor mass occurred when the inoculum consisted of as few as 10% HSV-TK-expressing tumor cells. The bystander effect was also demonstrated in i.p. tumor studies. Initial experiments demonstrated that prolonged survival (> 70 days) occurred when a mixture containing 50% HSV-TK-positive and 50% HSV-TK-negative cells was injected i.p. followed by GCV treatment. Further, survival was prolonged for mice with a preexisting HSV-TK-negative i.p. tumor burden by injecting HSV-TK-positive cells and GCV. These results suggest that genetic modification of tumor cells may be useful for developing cancer therapies.

Signal pathway regulation of interleukin-8-induced actin polymerization in neutrophils

Interleukin-8 (IL-8), a recently described peptide cytokine, is a neutrophil chemoattractant and activator that exerts effects similar to fMLP, yet their receptors and their roles in pathophysiology differ. The effect of IL-8 on the neutrophil cytoskeleton has not been well studied; therefore, we compared and contrasted the effects of IL-8 and fMLP on neutrophil actin conformation and on the signal pathway regulation of actin responses. IL-8 caused a rapid, dose-dependent increase in neutrophil F-actin content within 30 seconds. The maximum increase was twofold. These changes were accompanied by the development of F-actin-rich pseudopods, as noted with fluorescence microscopy and scanning electron microscopy. Selected biochemical inhibitors were used to study the regulation of the IL-8-induced actin changes. Incubation of neutrophils with 2 micrograms/mL pertussis toxin resulted in a 67% inhibition of the IL-8-induced F-actin increase. The protein kinase C (PKC) inhibitors, staurosporine and H7, did not inhibit the increase in F-actin caused by IL-8. IL-8 caused a rapid increase in neutrophil intracellular calcium that could be completely inhibited by the chelating agent 1,2-bis(o-aminophenoxy)ethane-N,N-N',N'-tetraacetic acid (BAPTA). However, BAPTA-treated neutrophils retained the ability to increase F-actin in response to IL-8. Similar results were seen with fMLP, indicating that, similar to fMLP, the IL-8-induced actin response is mediated through pertussis-toxin-sensitive G-proteins but is neither dependent on PKC nor increases in cytosolic calcium. Thus, although IL-8 and fMLP exert their effects on neutrophils through different receptors, the signal transduction pathways used and the effects on actin conformation and pseudopod formation are similar.