The Half-Life of Plasmic Degradation Products of Human Fibrinogen in Rabbits

Human fibrinogen and purified plasmic degradation fragments X (stages 1 and 2), D and E were labelled with 125-1 using the lactoperoxidase method. The chromatographic, elec-trophoretic and immunologic properties of the labelled proteins were found to be similar to those of non-labelled fragments. All the degradation products diffused rapidly (T½ 0.27–0.75 hours) from the intravascular space of rabbits, as compared with fibrinogen (4.26 hours). In addition, the metabolic half-life was found to be 49.3 hours for fibrinogen, as compared with only 5.1, 6.1, 2.3 and 1.4 for fragments X (stage 1), X (stage 2), D and E, respectively. The metabolic half-life roughly reflects the molecular size of the degradation products.

Irradiated mononuclear cells express significant in vitro cytotoxic activity: promise for in vivo clinical efficacy of irradiated mismatched donor lymphocytes infusion

BACKGROUND

Relapse of the original disease remains the most common cause of treatment failure after allogeneic hematopoietic stem cell transplantation (allo-SCT). Patients who relapse post-allo-SCT can achieve prolonged remission after donor lymphocyte infusion. Donor lymphocyte infusion as well as other immunotherapeutic strategies are usually complicated by severe graft versus host disease.

AIM

In the present study, we examined the effect of irradiation on the cytotoxic activity of mononuclear cells (MNCs).

MATERIALS & METHODS

Cytotoxic activity of fresh and irradiated MNCs from healthy donors was tested against the leukemic cell line K562 and against fresh leukemic cells from patients with acute myeloid leukemia. Cytotoxicity was assessed by using a flow-cytometry assay.

RESULTS & DISCUSSION

Interestingly, we observed that 25 Gy irradiated MNCs retain significant cytotoxic activity against K562. Based on these in vitro data, the safety and efficacy of irradiated haploidentical, IL-2-activated lymphocytes were tested in six patients after allo-SCT. Acute skin graft versus host disease developed in two patients and was resolved after a short course of steroids. One patient with mixed chimera converted to full donor chimera after infusion of irradiated donor cells.

CONCLUSION

The efficacy of irradiated haploidentical lymphocytes should be further tested in a larger number of patients.

Assessment of CD4 T-lymphocyte reactivity by the Cylex ImmuKnow assay in patients following allogeneic hematopoietic SCT

After allogeneic hematopoietic SCT (alloHSCT), immunosuppressed patients are susceptible to opportunistic infections, and uncontrolled function of the graft can result in GVHD. Accurate immune monitoring may help early detection and treatment of these severe complications. Between October 2005 and November 2007, a total of 170 blood samples were collected from 40 patients after alloHSCT in the Hadassah Hebrew University Medical Center and from 13 healthy controls. We utilized the Cylex ImmuKnow assay for CD4 ATP levels to compare known clinically immunocompromised vs immunocompetent patients after alloHSCT. We also compared the reconstitution of WBC count to the ImmuKnow results and clinical status. The patients' clinical course correlated with the stratification of immune response established by the ImmuKnow assay for solid organ transplantation (immunocompetent vs immunocompromised), and this often differed from their WBC count. On the basis of our observations, we conclude that the ImmuKnow assay is a simple and fast immune-monitoring technique for patients undergoing alloHSCT, with potential to predict clinical course and facilitate prompt management of post-HSCT complications. The assay should be evaluated prospectively in clinical trials.

Post-autologous stem cell transplantation administration of rituximab improves the outcome of patients with aggressive B cell non-Hodgkin's lymphoma

The major cause of treatment failure following high-dose therapy with autologous stem cell transplantation (ASCT) for aggressive B cell non-Hodgkin's lymphoma (NHL) is persistent disease or recurrence. We describe our experience with the administration of rituximab post-ASCT, either as maintenance therapy or for the treatment of relapsed disease in patients with aggressive B cell NHL. Fifty-six patients achieved complete remission post-transplant, and 19 of them received maintenance with rituximab. Maintenance with rituximab resulted in statistically significant superior outcome in terms of progression free (PFS; p = 0.002) and overall survival (OS; p = 0.011). The median PFS and OS of patients in the maintenance arm has not been reached yet, while the median PFS and OS of patients in the control arm were 29 and 42 months, respectively. Fifty-four patients had disease progression or relapsed post-ASCT, and 15 of them received rituximab in combination with chemo- and/or radiotherapy in order to achieve disease remission. Therapeutic administration of rituximab resulted in statistically significant prolongation of OS (p = 0.021). The median OS of patients treated with rituximab was 17 months, while median OS of patients in the control group was 10 months. We consider that the results of our study are promising but need to be verified within large randomized trials.

A new induction protocol for the control of steroid refractory/dependent acute graft versus host disease with alefacept and tacrolimus

BACKGROUND AIMS

We have shown previously that alefacept is effective in acute steroid resistant/dependent and chronic extensive graft versus host disease (GvHD) with a protocol using timings similar to those used for psoriasis treatment. In this study, we describe the use of an alefacept induction (e.g. for 7 consecutive days) followed by a bi-weekly maintenance treatment in combination with tacrolimus for acute steroid resistant/dependent GvHD 1, 3.

METHODS

Sixteen patients were treated in this cohort, most with refractory GvHD. The pre-treatment GvHD grade ranged from 2 to 4 (median 3), involving the skin 16, gut 11 and liver 5.

RESULTS

Twelve out of the 16 patients showed a response. As with the first protocol, the response of GvHD in the skin was fastest. In contrast to our previous protocol, however, the gastro-intestinal (GI) GvHD response was faster (P=0.05 compared with the first cohort). A hepatic response was seen in 4/6 patients and was complete in three. All responses were durable, including mucocutaneous, gut and liver GvHD. In all responding patients we were able to decrease the steroid dose significantly and in seven it was completely withdrawn.

CONCLUSION

Alefacept induction is safe in acute steroid resistant/dependent GvHD and may be more effective therapeutically than our previous alefacept protocol. We speculate that alefacept initiates an allo-versus-allo cellular effect through its Fc receptor.

Targeted immunotherapy with intentionally mismatched rIL-2 activated donor lymphocytes in an attempt to eliminate minimal residual disease in patients with high-risk metastatic cancer

21175

Background: Graft-versus-leukemia and graft-versus-tumor (GVT) effects following stem cell transplantation are well established, however, procedure related toxicity and mortality are unavoidable. In addition to limited efficacy following stem cell transplantation (SCT), graft-versus-host disease (GVHD) is unavoidable. Our protocol was designed to induce more potent anti-cancer immunotherapy by rIL-2 activated intentionally mismatched donor lymphocytes (MDL) at the stage of minimal residual disease (MRD) outpatient procedure with no SCT avoiding GVHD. Methods: Optimizing MDL was accomplished by cyclophosphamide 1,500 mg/m2 and 2 injections of alpha interferon (3x106IU) for more effective immunotherapy, aiming for depletion of regulatory T cells, followed by infusion of haploidentically mismatched lymphocytes activated with rIL-2 (6,000 IU/ml) for 4 days. On the day of cell infusion, patients received rIL-2 6x106 IU subcutaneously outpatient for 5 days. Results: A total of 41 (age 5–73, median 52) high risk patients were included: metastatic breast 13; colorectal 3; gastric 3; pancreatic 3; melanoma 3; head & neck 3; glioblastoma 2; and 6 with other solid tumors. Five patients had resistant hematological malignancies: multiple myeloma 2; non-Hodgkin's lymphoma 2 and Hodgkin's disease 1. 6 patients received lymphocytes with bispecific antibodies for targeted cell-therapy (3 with catumaxomab against CD3 & epithelial cell adhesion molecule (EpCAM); 3 with ertumaxomab directed against CD3 & Her-2/neu WHO toxicity >grade 2 was noted. 14 of evaluable patients are alive. 10/32 with solid tumors are alive, 7 with no evidence of disease > 9–91 (median 17) months (4 breast; 1 squamous cell; 1 head & neck; 1 prostate). Of 5 patients with hematological malignancies 4 are alive and disease free >18–96 (median 46) months. Conclusions: Safe induction of GVT effects may be accomplished by MDL, preferably targeted with bispecific antibodies after cyclophosphamide conditioning lymphocytes are more potent and act faster than matched lymphocytes and GVHD is avoided by rejection of donor lymphocytes. When applied at a stage of MRD, such treatment may result in operational cure.

No significant financial relationships to disclose.

A prospective, double-blind phase II study evaluating the safety and efficacy of a topical histamine gel for the prophylaxis of oral mucositis in patients post hematopoietic stem cell transplantation

The aim of this study was to evaluate the safety, tolerability and efficacy of a topical gel containing histamine dihydrochloride (HDC) versus a placebo gel in preventing oral mucositis in hematopoietic stem cell transplantation (HSCT) patients. A total of 45 patients post-HSCT were enrolled in a prospective longitudinal, placebo-controlled, double-blind study. Patients were evaluated twice weekly for oral mucositis (OMAS, NCI score), oral pain (VAS), oral function and salivary flow rate. Compliance was assessed using a patient diary. Oral mucositis developed in 85% of the HDC group and 63% of the placebo group. The mean maximal intensity for NCI score was 1.45+/-1 in the HDC group and 1.21+/-1.27 in the placebo group (P=0.37). The mean duration of oral mucositis was 4.7+/-3.6 and 2.33+/-2.23 days in the HDC and placebo groups, respectively (P=0.06). The same trends were measured with OMAS. Visual analogue scale for oral pain and oral function was not significantly different between the two groups. Histamine dihydrochloride was found to be safe. In the search for topical agents for the prevention of mucositis, we found that HDC neither improves nor worsens oral mucositis in HSCT patients. The balance between the pro- and anti-inflammatory effects of HDC should be investigated further in order to acquire a clinically effective topical medication based on its anti-inflammatory properties.

The half-life of plasmic degradation products of human fibrinogen in rabbits

Human fibrinogen and purified plasmic degradation fragments X (stages 1 and 2), D and E were labelled with 125-I using the lactoperoxidase method. The chromatographic, electrophoretic and immunologic properties of the labelled proteins were found to be similar to those of non-labelled fragments. All the degradation products diffused rapidly (T 1/2 0.27-0.75 hours) from the intravascular space of rabbits, as compared with fibrinogen (4.26 hours). In addition, the metabolic half-life was found to be 49.3 hours for fibrinogen, as compared with only 5.6, 6.1, 2.3 and 1.4 for fragments X (stage 1), X (stage 2), D and E, respectively. The metabolic half-life roughly reflects the molecular size of the degradation products.