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Biomedical subjects

M K Brenner

Publications and source records attributed to M K Brenner.

At least 127 records · Page 7Linked to original sources
PubMed1992

An approach for the analysis of relapse and marrow reconstitution after autologous marrow transplantation using retrovirus-mediated gene transfer.

Autologous bone marrow transplantation (ABMT) is widely used as treatment for malignant disease. Although the major cause of treatment failure is relapse, it is unknown if this arises entirely because of residual disease in the patient or whether contaminating cells in the rescuing marrow contribute. Attempts to purge marrow of its putative residual malignant cells may delay hematopoietic reconstitution and are of uncertain efficacy. We now describe how retrovirus-mediated gene transfer may be used to elucidate the source of relapse after ABMT for acute myeloid leukemia and to evaluate the efficacy of purging. Clonogenic myeloid leukemic blast cells in patient marrow can be transduced with the NeoR gene-containing helper-free retrovirus, LNL6, with an efficacy of 0% to 23.5% (mean, 10.5%). Transduced colonies grow in selective media and the presence of the marker gene can be confirmed in individual malignant colonies by polymerase chain reaction. If such malignant cells remain in harvested "remission" marrow, they will therefore be marked after exposure to LNL6. Detection of the marker gene in the malignant cells present at any later relapse would be firm evidence that residual disease contributed to disease recurrence, and would permit rapid subsequent evaluation of purging techniques. The technique also marks normal marrow progenitors from patients with acute myeloblastic leukemia. These colony-forming cells can be detected in long-term marrow cultures at a frequency of 1% to 18% for up to 10 weeks after exposure to the vector. Animal models and analysis of probability tables both suggest that these levels of marking in vitro are sufficient to provide information about the mechanisms of relapse and the biology of marrow regeneration in vivo. These preclinical data form part of the basis for current clinical studies of gene transfer into marrow before ABMT.

Bone Marrow↗
PubMed1992

Retrovirus-mediated gene transfer as an approach to analyze neuroblastoma relapse after autologous bone marrow transplantation.

Disseminated neuroblastoma is a malignancy of children often treated by intensive chemotherapy/radiotherapy followed by autologous bone marrow transplantation (ABMT). A high proportion of those treated subsequently relapse. It is unknown if relapse is a consequence of residual disease in the patient or of contaminating malignant cells remaining in the infused marrow, which, of necessity, is harvested and stored prior to ablative chemotherapy/radiotherapy. The assumption that residual cells in the infused marrow contribute to relapse has lead to the adoption of marrow purging prior to reinfusion. However, neither the necessity nor the efficacy of the procedure have been established. We now show how retroviral-mediated gene transfer using the LNL6 vector may resolve this issue. Clonogenic neuroblastoma cells in patient marrow can be transduced and the NEOR gene detected by observing individual neuroblastoma cell colony growth in G418, and by polymerase chain reaction (PCR) of individual colonies. Efficiency of transduction is between 0 and 13.5%. If marrow is exposed to LNL6 prior to infusion and marked cells are detected at the time of relapse, this would demonstrate that infused marrow contributed to disease recurrence. The technique could then be used to analyze the efficacy of marrow purging techniques. Since normal progenitor cells from these patients are also marked, the technique can be used to study factors that modify reconstitution and transducibility of infused marrow. Clinical studies using this approach have now begun.

Base Sequence↗
PubMed1992

Effects of anti-TNF monoclonal antibody infusion in patients with hairy cell leukaemia.

Tumour necrosis factor (TNF) can act as an autocrine growth factor for hairy cell leukaemia (HCL) cells. The TNF produced by the malignant clone may also inhibit normal haematopoiesis thereby contributing to the cytopenias observed in patients with the disease. We have studied the effects of infusing a murine monoclonal anti-TNF antibody in three patients with HCL. In two patients receiving 0.5 mg of antibody/kg on alternate days for 12 d, the drug was well tolerated. The third patient received 2 mg/kg on alternate days and developed symptoms of serum sickness by day 9. In two patients with severe B-lymphocytopenia, circulating CD19 and CD20 positive, B-cells were restored to normal, the majority of which were negative for the HCL-associated marker CD11c. B-lymphocyte recovery was associated with a rise in serum immunoreactive IL-6 and with an early rise in immunoreactive TNF. These short courses of anti-TNF MAb treatment had modest effect on the tumour burden, producing a reduction in splenomegaly in one patient. Exploration of the effects of more prolonged administration of higher dose anti-TNF antibody will only be feasible when less immunogenic MAbs are available.

Animals↗
PubMed1992

IL-2 infusion abrogates humoral immune responses in humans.

Although IL-2 infusion enhances cell-mediated cytotoxicity in patients with neoplastic disease, administration is paradoxically associated with a modest fall in total serum IgG and an increased risk of infection. We now show that the adverse effects of IL-2 infusion on the humoral immune system are substantial. Although IL-2 induces the B cell growth and differentiating factors IL-4 and IL-6, infusion abrogates primary antibody responses entirely and reduces secondary antibody responses 50-fold following antigen challenge. There is no evidence of the generation of cells with suppressive activity on B cells but IL-2 increases the ratio of circulating virgin:memory cells. These results may help to explain the increased rate of bacterial infection in patients receiving IL-2. As IL-2 plays a central role in the generation of an immune response, the finding that it is also sufficiently immunosuppressive to inhibit primary- and secondary-type antibody responses suggests that exploration of the underlying mechanisms may provide insights into immune system homeostasis and may offer new approaches to therapeutic immunosuppression.

Adolescent↗
PubMed1992

Current strategies for treatment of acute myeloid leukemia at St Jude Children's Research Hospital.

We examined the feasibility of maintaining specific plasma concentrations of ara-C and VP-16 in children with AML. Sixty-one children were treated with 6 sequential cycles of intensive chemotherapy consisting of: (1) cytarabine (ara-C)/VP-16, (2) ara-C/daunorubicin (Dauno), (3) VP-16/amsacrine (m-AMSA), (4) VP-16/5-azacytidine (5-Az), (5) ara-C/Dauno, and (6) ara-C/VP-16. Fifty-nine children had de novo AML, and 2 had a previous myelodysplastic syndrome. The number of patients with each specific FAB subtype was: M0-1; M1-7; M2-24; M3-7; M4-5; M5-11; and M7-6. Simultaneous continuous infusions of ara-C and VP-16 (cycle 1) given at individualized doses to achieve drug plasma concentrations of 1 microM and 30 microM, respectively, produced complete remission (CR) in 26 of 61 patients (43%); an additional 17 patients entered CR after Dauno/ara-C (cycle 2), and one patient required 4 cycles of chemotherapy to achieve CR (total CR rate = 72%). The preliminary 2-year event-free survival (EFS) for patients with FAB-M1 and -M2 AML was only 15% versus 40% for those with FAB-M4 and -M5 AML. Overall, 21 of the 61 patients remain in CR (2-yr EFS = 29%). We conclude that intense treatment with ara-C and VP-16 at doses individualized to achieve target plasma concentrations is feasible although severely myelosuppressive. It results in an acceptable CR rate, but does not improve EFS.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Chloroadenosine↗
PubMed1992

Escalating sequential high-dose carboplatin and etoposide with autologous marrow support in children with relapsed solid tumors.

Thirty patients with relapsed pediatric solid tumors received high-dose carboplatin and etoposide with autologous marrow support in a dose-escalation trial. These patients had received extensive prior treatment, which included both cisplatin and etoposide in 25 cases. Six patient cohorts received carboplatin in doses of 1200-2100 mg/m2 and etoposide in doses of 960-1500 mg/m2. All courses were associated with severe neutropenia and thrombocytopenia. The median times from bone marrow infusion to granulocyte recovery (> 0.5 x 10(9)/l) and platelet recovery (> 50 x 10(9)/l) were 33 and 28 days, respectively, with similar findings for all dosage levels. The frequency of non-hematologic toxicities was generally low, although hyponatremia (Na+ < 129 mEq/l) was seen in one-third of the courses. Hepatoxicity was dose-limiting and was significantly associated with the cumulative prior cisplatin dose (p = 0.006). There were four toxic deaths (CNS hemorrhage, alfa-streptococcal sepsis, Candida sepsis, and enterocolitis). Eleven patients received a second course of therapy; toxicity profiles and times to hematologic recovery were similar for the two courses. Clinical responses were observed at all dosage levels. Eleven of 26 evaluable patients achieved a clinical response (one complete, 10 partial). The majority of responses were in patients with neuroblastoma (six of 16) or Hodgkin's disease (two of three). For phase II clinical trials, we recommend dosages of 2100 mg/m2 of carboplatin and 1500 mg/m2 of etoposide for children with prior cumulative cisplatin exposure < 960 mg/m2. This carboplatin dose represents a three- to four-fold increase over pediatric doses tolerated without bone marrow support.

Adolescent↗
PubMed1992

Reconstitution of the T cell receptor alpha beta repertoire in recipients of allogeneic BMT.

This report describes the qualitative analysis of T cell receptor (TCR) repertoire regeneration in recipients of BMT. RNA samples from patient and control peripheral blood lymphocytes were prepared and tested for the presence of multiple V alpha and V beta transcripts by the polymerase chain reaction. TCR V gene expression was highly diverse within the first 6 months post-transplantation in recipients receiving either T cell-depleted or T cell-replete marrow, and in HLA mismatched as well as matched donor-recipient pairs. The sequencing of TCR message from BMT recipients also demonstrated J gene diversity and apparently normal junctional diversity at the V-J alpha join. Thus, T cell pools in BMT recipients are largely heterogeneous, not mono- or oligoclonal.

Adolescent↗
PubMed1992

Immunotherapy of leukemia.

There is now a substantial body of evidence that the immune system can help eradicate leukemia. While alloreactive T cells may play this role after allogeneic bone marrow transplants (BMT), T-cells may also exist which are able to recognize processed leukemia specific antigens such as mutant oncogenes/fusion proteins. In addition, a contribution may come from major histocompatibility complex unrestricted but leukemia-selective killing by natural killer/activated killer cells. These effector mechanisms may be augmented by administration of interleukin 2 after chemotherapy or autologous BMT. Finally, techniques of gene marking may help to determine more accurately the site and characteristics of minimal residual disease and thereby improve the targeting of immune mediated eradication of leukemia.

Humans↗
PubMed1991

Homeostatic action of interleukin-4 on endogenous and recombinant interleukin-2-induced activated killer cell function.

Cytokine-secreting, major histocompatibility complex-unrestricted activated killer (AK) cells are toxic to a wide range of virus-infected or malignant target cells and may be generated endogenously, eg, after bone marrow transplantation, or by infusion of cytokines such as recombinant interleukin-2 (rIL-2). Although AK cells secrete cytokines such as gamma-interferon and tumor necrosis factor, which are themselves able to recruit fresh cytokine-secreting AK cells, activation in both settings is short-lived, implying the existence of homeostatic regulatory mechanisms. We now demonstrate one mechanism by which rapid homeostasis is achieved. We show that IL-4 is produced in patients with both endogenously and exogenously generated AK cells. The cytokine was detected in serum after marrow transplantation, and IL-4 transcripts appeared in circulating lymphocytes during rIL-2 infusion. Although IL-4 inhibited the induction phase of AK cell function, it had no significant inhibitory effect on the ability of AK cells from these individuals to respond to restimulation. Nonetheless, neutralization of the IL-4 induced during cell activation doubled the half-life of AK function, once activating stimuli were removed, from 18 to 44 hours and produced a 2-log increase in AK cell secretion of tumor necrosis factor and gamma-interferon. These data suggest that IL-4 induced in vivo during lymphocyte activation abbreviates AK cell responses once the triggering stimuli have been removed. Neutralization of endogenous IL-4 in vivo by appropriate monoclonal antibodies might prolong the duration of AK function.

Bone Marrow Transplantation↗
PubMed1991

Graft-versus-host reactions and bone-marrow transplantation.

Three areas of bone-marrow transplantation have developed particularly rapidly during the past year. First, increasing numbers of bone-marrow transplants using matched unrelated donors or HLA-mismatched family members have been successfully performed. Second, trials of recombinant hemopoietic growth factors have shown these agents can accelerate hemopoietic recovery after bone-marrow transplant and reduce the incidence of infections and other post-transplant complications. But potentially the most important advances have come in a series of separate observations, which in conjunction suggest mechanisms by which the anti-leukemic activity of an allograft may be separated from its ability to induce graft-versus-host disease.

Animals↗
PubMed1991

Graft versus leukaemia effects after marrow transplantation in man.

A graft versus leukaemia (GvL) effect makes a significant contribution to the lower risk of relapse seen in patients after BMT compared with patients receiving chemotherapy alone. Both T cell-dependent and T cell-independent effectors of GvL exist, and both may play an important role in the elimination of minimal residual disease after BMT. There is evidence that GvL activity may be separable from GvHD either by identifying T cell clones recognizing specific leukaemia antigens or by using immunomodulatory drugs or cytokines to enhance T cell-independent GvL mechanisms which operate without alloreactivity and therefore without concomitant exacerbation of GvHD. These approaches should improve survival after both autologous and allogeneic BMT.

Bone Marrow Transplantation↗
PubMed1991

Interleukin 2 infusion induces haemopoietic growth factors and modifies marrow regeneration after chemotherapy or autologous marrow transplantation.

Administration of interleukin 2 (IL2) to patients with minimal residual malignant disease following myeloablative chemo-radiotherapy may augment immune reconstitution and reduce the risk of relapse by increasing cytotoxic effector function and cytokine dependent killing directed at residual malignant cells. The ability of IL2 generated activated killer cells to inhibit haemopoietic progenitor cells and to release gamma-interferon (gamma IFN) and tumour necrosis factor (TNF) may, however, retard haemopoietic recovery, as both TNF and gamma IFN inhibit normal myelopoiesis in vitro. To determine the effect of IL2 infusion on myeloid regeneration in vivo, we have examined haemopoietic recovery in patients receiving this cytokine following autologous marrow transplantation or ablative chemotherapy. We find that IL2 infusion accelerates neutrophil recovery and that granulocyte-macrophage colony stimulating factor (GMCSF) and IL3 mRNA become detectable in circulating mononuclear cells. Induction of TNF by IL2 may also contribute to subsequent acceleration of myelopoiesis by initiation of GM-CSF mRNA synthesis in patient marrow fibroblasts. These results show that IL2 infusion may facilitate myeloid recovery when administered during the period of haemopoietic regeneration following ablative chemoradiotherapy.

Acute Disease↗
PubMed1991

Possible mechanism of action of interferon alpha in chronic B-cell malignancies.

Recent evidence suggests that tumour necrosis factor alpha (TNF) is an autocrine growth factor for the chronic B-cell malignancies hairy cell leukaemia (HCL) and some cases of B-chronic lymphocytic leukaemia (B-CLL). Incubation with TNF in vitro has been shown to increase viability, DNA synthesis and the expression of the protooncogenes myc, fos and jun in the tumour cells from these patients. TNF in vitro also increases expression of TNF-mRNA, suggesting the existence of an autocrine growth loop for TNF in these cells. Current experiments are compatible with the hypothesis that interferon alpha (IFN) interferes with this autocrine growth loop in HCL and B-CLL by stimulating degradation of messenger RNAs (mRNAs) for a number of cytokines including that of TNF. This RNA degradation may be mediated through induction of the enzyme 2,5 oligo-A synthetase with consequent increased synthesis of 2,5 oligo-A which is known to stimulate the activity of a latent ribonuclease capable of degrading cytokine mRNAs. Circulating tumour-derived TNF may also contribute to the pancytopenia in HCL and B-CLL. Whether cytokine autocrine growth loops are important in other B-cell malignancies, e.g. myeloma and non-Hodgkin's lymphoma, and subject to IFN-stimulated breakdown needs further study.

B-Lymphocytes↗
PubMed1991

IL2 activated killer cells may contribute to cytomegalovirus induced marrow hypoplasia after bone marrow transplantation.

Cytomegalovirus (CMV) infection remains the commonest cause of infective death following allogeneic bone marrow transplantation (BMT). CMV disease post-BMT occurs in the context of compromised cellular defence mechanisms and is associated with marrow hypoplasia and pneumonitis. However, CMV infection induces release of interleukin 2 (IL2) which in turn generates MHC unrestricted lymphokine activated killer (LAK) cells. We have investigated whether recruitment of IL2 activated MHC unrestricted defence mechanisms post-transplant can be implicated in the marrow hypoplasia that frequently accompanies CMV infection. The results show that IL2 activated peripheral blood mononuclear cells (PBMC) have substantial cytotoxicity against MHC matched and MHC mismatched marrow fibroblasts but that this activity is not specific for CMV infected fibroblasts; uninfected target cells are also equally killed. Furthermore, post-BMT PBMC show greater responsiveness to IL2 than normal PBMC in killing of marrow fibroblasts. We provide a hypothesis from these observations which may explain some of the consequences of CMV infection post-BMT. Local production of IL2 activated cytotoxic cells which would be generated during CMV infection would damage uninfected as well as infected marrow fibroblasts and thereby could compromise haemopoietic growth factor production by marrow fibroblasts. Similarly generated cytotoxicity in the lung may accompany CMV pneumonitis. Our results suggest that administration of anti-IL2 receptor antibody may have a therapeutic role in CMV disease post-BMT as has recently been shown in graft-versus-host disease.

Adolescent↗
PubMed1991

Failure of purged autologous bone marrow transplantation in high risk acute lymphoblastic leukaemia in first complete remission.

Patients in first remission of acute lymphoblastic leukaemia (ALL) considered to be at high risk of relapse were offered autologous bone marrow transplantation (ABMT) using purged marrow as a therapeutic alternative to cranial irradiation and maintenance chemotherapy. Twenty-seven bone marrows taken in remission, were purged using monoclonal antibodies (anti CD7 for T lineage and anti CD10 and/or anti CD19 for B lineage leukaemias) plus rabbit complement. Retrospective analysis of 19 purged marrows by immunophenotyping or immunoglobulin gene rearrangement studies demonstrated no evidence of disease. Engraftment was seen in 26 of the patients. No correlation was found between the numbers of infused nucleated cells or colony forming units-granulocyte-macrophage (CFU-GM) and subsequent engraftment kinetics. The actuarial disease-free survival (DFS) is 32% at 7 years (median follow-up 3.4 years). There were two transplant related deaths (actuarial risk 8%); the main cause of treatment failure has been disease recurrence with an overall actuarial risk of 67%; 76% for T-ALL (five of nine), 62% for common ALL (five of 10), two of five pre B and none of three patients with B-ALL. In these 27 high risk patients in vitro purging of remission marrow as part of ABMT appears not to improve patient outcome, although confirmation of this would require a randomized trial.

Adolescent↗
PubMed1991

IL-4 acts as a homeostatic regulator of IL-2-induced TNF and IFN-gamma.

Interleukin-4 (IL-4) is a cytokine secreted by interleukin-2 (IL-2)-activated lymphocytes. IL-2-stimulated lymphocytes also secrete two cytokines, tumour necrosis factor (TNF) and gamma-interferon (IFN-gamma), which contribute to effector function and which may themselves recruit fresh, cytokine-secreting effector cells. We have now investigated whether the IL-4 induced is able to homeostatically regulate secretion of the TNF and IFN-gamma. Peripheral blood mononuclear cells or lymphocytes from normal donors and from patients with neoplastic disease were cultured in the presence of IL-2 alone, IL-4 alone or with both cytokines. IL-2 induced high levels of TNF and IFN-gamma secretion in both groups. The addition of recombinant IL-4 to these IL-2-stimulated cultures lead to significant inhibition of IFN-gamma and TNF production. IFN-gamma secretion was reduced by 50-99% in normal donors and by between 11% and 99% in patients (P less than 0.001). TNF levels induced by IL-2 were similarly reduced by IL-4 both in normal donors (P less than 0.003) and in patients (P less than 0.01). These inhibitory effects were produced by IL-4 at doses of IL-2 attainable in vivo. Inhibition appears to represent a homeostatic regulatory mechanism which may limit recruitment of fresh activated killer (AK) cells. When endogenous IL-4 activity in IL-2-activated lymphocytes was blocked by anti-IL-4 antibody, significantly higher levels of IFN-gamma and TNF were secreted (P less than 0.05). Since both TNF and IFN-gamma may contribute to the anti-neoplastic action of IL-2, manipulating the level of IL-4 activity in vivo could augment the benefits of IL-2 immunotherapy.

Bone Marrow Transplantation↗