PubMed Health⌕ Search

Biomedical subjects

K R Meehan

Publications and source records attributed to K R Meehan.

33 records · Page 2Linked to original sources
PubMed1997

Interleukin-2-activated hematopoietic stem cell transplantation for breast cancer: investigation of dose level with clinical correlates.

Incubating hematopoietic stem cells with IL-2 in vitro for 24 h generates cytotoxic T cells. When infused into patients, these cells may stimulate a graft-versus-tumor (GVT) effect. This clinical trial was designed to assess the ability of IL-2 activated peripheral blood stem cells (PBSC) to reconstitute hematopoiesis, to investigate dose levels and dose-limiting toxicities of IL-2, and to evaluate clinical results and preliminary laboratory effects using a combination of IL-2-activated autologous PBSC followed by IL-2 after transplantation. Sixty-one women with stage II-IV breast cancer were treated. After the administration of carboplatin (200 mg/m2/day for 3 days) and cyclophosphamide (2 g/m2/day for 3 days), patients received autologous PBSC that were cultured in IL-2 for 24 h followed by parenteral administration of IL-2 beginning the day of transplantation. Three escalating doses of IL-2 were evaluated with increasing duration up to 4 weeks. Of the 57 patients receiving IL-2 after tranplantation, 19 patients (33.3%) were unable to complete the planned course of IL-2 therapy due to persistent fevers (n = 9), diarrhea (n = 2), pulmonary capillary leak syndrome (n = 3), development of a rash (n = 1), atrial fibrillation (n = 1), or patient's request (n = 3). One death occurred during hospitalization. Engraftment of neutrophils occurred on day 11.5 (mean; range 8-21 days) and platelets on day 11.7 (mean; range 7-33 days). The maximal tolerated dose of IL-2 was 6 x 10(5) IU/m2/day for 4 weeks. Disease-free survival rates for all stages were comparable to current reports in the literature. Preliminary laboratory evaluations include FACScan analysis of the IL-2 activated PBSC demonstrating an increased percentage of CD3+, CD25+, HLA-DR+ T cells. Phenotypically similar cells were present in peripheral blood samples of patients when tested 15 days after transplantation. This study demonstrates successful engraftment with IL-2-activated PBSC after high-dose chemotherapy for women with stage II-IV breast cancer. The regimen is feasible and, although toxicities are common, they are manageable and correlate with increasing dose and duration of IL-2.

Adult↗
PubMed1997

A pilot study evaluating interleukin-2-activated hematopoietic stem cell transplantation for hematologic malignancies.

Cytotoxic effector cells are generated when autologous hematopoietic cells (HSC) are cultured with IL-2 for 24 h. Infusion of these cells followed by IL-2 administration may moderate a graft-versus tumor (GvT) effect in vivo. Sixteen patients--7 with non-Hodgkin's lymphoma (NHL), 2 with AML, 4 with multiple myeloma (MM), and 3 with Hodgkin's disease (HD)--received busulfan (4 mg/kg/day for 4 days) and cyclophosphamide (60 mg/kg/day for 2 days) or cyclophosphamide/TBI (1320 cGy). Autologous HSC were activated by culturing with IL-2 for 24 h before reinfusion. Subcutaneous administration of IL-2 began after engraftment at 1.8 x 10(6) IU/m2/day for 1-4 weeks. Neutrophil engraftment occurred on day 13.1 (median) (range 9-45 days), and platelet engraftment occurred on day 19.3 (median) (range 7-54 days) for 15 patients, with delayed engraftment observed in 3 patients. One patient experienced a fatal cardiac arrhythmia. Five patients developed transient skin rashes with histologic evaluation demonstrating findings consistent with GvHD. At 17 months (median) (range 7-23 months), 9 patients are alive, with 6 patients remaining disease free. This pilot trial demonstrates mild to moderate toxicities and a possible delay in platelet engraftment. Further trials will determine the optimal dose and duration of IL-2 therapy and possible impact of this therapy on survival. Laboratory investigations are evaluating the presence of autologous GvHD and a possible GvT effect.

Adolescent↗
PubMed1997

Access to bone marrow transplantation for leukemia and lymphoma: the role of sociodemographic factors.

PURPOSE: Use of bone marrow transplantation (BMT), a complex, costly treatment for many forms of cancers, has increased significantly in recent years. The increasingly competitive health care marketplace raises concerns about patient access to costly medical procedures such as BMT. We attempted to evaluate patient access to BMT for the treatment of leukemias and lymphomas. METHODS: We analyzed inpatient hospital discharge data from four states (California, Maryland, Massachusetts, and New York) for 2 years (1988 and 1991) to examine whether the use of BMT for patients with either leukemia or lymphoma varies by sociodemographic characteristics and insurance coverage. We developed a sorting algorithm to collapse the discharge data into patient level records. We used logistic regression to analyze the odds of receiving a BMT stratified by disease type (leukemia or lymphoma). RESULTS: After controlling for other factors, black patients with leukemia are 51% to 53% as likely as whites, while black patients with lymphoma are 34% to 45% as likely as white patients to undergo a BMT (P < .05). Medicaid, self-pay patients, and Health Maintenance Organization (HMO) enrollees with either leukemia or lymphoma are significantly less likely to undergo a BMT compared with patients with private insurance. Younger patients are significantly more predisposed to undergo a BMT than older patients. The odds of receiving a BMT have increased over time, but the rates of increase vary by state. Consistent with clinical expectations, the relative odds of BMT vary significantly by type of leukemia or lymphoma. CONCLUSION: Substantial variation exists in access to BMT for patients with either leukemia or lymphoma. Black patients, those enrolled in HMOs, those covered by Medicaid, and self-pay patients were less likely to receive a BMT when admitted for either leukemia or lymphoma. These findings raise concerns about access to cancer treatments for patients in the current health care system.

Black or African American↗
PubMed1996

Allogeneic bone marrow transplantation in a patient with hypereosinophilic syndrome.

We describe a 32-year-old man with idiopathic hypereosinophilic syndrome (HES) who presented with pulmonary dysfunction, thrombocytopenia, lymphadenopathy, and hepatosplenomegaly. The patient developed progressive disease on prednisone and hydroxyurea therapy, and he underwent a successful allogeneic bone marrow transplantation (BMT). The patient is asymptomatic with no evidence of eosinophilia 30 months after transplantation. There is currently no cure for patients with HES, and BMT should be considered in selected patients.

Adult↗
PubMed1996

Stem cell transplantation with chemoradiotherapy myeloablation and interleukin-2.

Interleukin 2 (IL-2) stimulates the proliferation of T-cells both in vitro and in vivo. When murine or human peripheral blood (PB) or bone marrow (BM) mononuclear cells are incubated with IL-2 in vitro for 24 hours, cytotoxic T-cells are generated. If these activated cells are infused into mice, the enhanced cytotoxicity continues if low dose IL-2 is administered. This combination of administering activated cells with the subsequent low dose IL-2 infusion results in enhanced tumor cell destruction and improved survival rates in mice with acute myeloid leukemia. The encouraging results of these laboratory experiments prompted the initiation of phase I clinical trials in patients with refractory/relapsed hematologic malignancies and patients with breast cancer (Stages II-IV). Results from these trials demonstrate that stem cell transplantation with IL-2 activated stem cells (either PB or BM) with or without parenteral administration of IL-2 results in hematopoietic reconstitution with mild-to-moderate toxicities. This regimen also generates cutaneous and visceral autologous graft versus host disease (AuGVHD). The majority of our patients with relapsed/refractory hematologic malignancies or breast cancer developed either clinical and/or histological evidence of AuGVHD. Further studies are being conducted to determine if patients who develop AuGVHD experience improved disease-free survival from a possible autologous graft versus tumor (GVT) effect. Current laboratory evaluations include the elucidation of the pathogenesis of AuGVHD and molecular evaluation of the purging efficacy of IL-2.

Animals↗
PubMed1996

Hematopoietic potential of IL-2-cultured peripheral blood stem cells from breast cancer patients.

Patients receiving autologous transplants for various malignancies generally experience an increased incidence of relapse compared with patients receiving unmanipulated allogeneic transplants. We initiated a protocol for IL-2 activation of peripheral blood stem cells (PBSC) for induction of in vitro and in vivo autologous graft-versus-tumor (GVT) activity in patients with breast cancer. In this study we analyzed the effects of 24 h of IL-2 incubation on the hematopoietic potential of PBSC from these patients. Cells collected by leukapheresis were first cryopreserved and stored in liquid nitrogen, then thawed rapidly and incubated with IL-2 in a serum-free system for 24 h, with samples analyzed before and after incubation. Although there was a significant drop in mononuclear cells (MNC) (from 4.5 to 3.7 x 10(8)/kg) and CD34+ cells (from 12.3 to 7.5 x 10(6)/kg) after 24 h in culture, there was no significant change in colony-forming units (CFU) (from 12.5 to 11.5 x 10(5)/kg). Time to engraftment (neutrophils: < 0.5 x 10(9)/l; platelets: > 20 x 10(9)/l) was comparable to a cohort of similar patients receiving non-cultured PBSC transplants. These results indicate that mobilized frozen/thawed PBSC which have been cultured in IL-2 for 24 h retain adequate potential for hematopoietic reconsistution in this group of patients.

Breast Neoplasms↗
PubMed1995

Pretreatment fibrinogen levels are associated with response to chemotherapy in patients with small cell carcinoma of the lung: Department of Veterans Affairs Cooperative Study 188.

Small cell carcinoma of the lung (SCCL) responds commonly to combination chemotherapy but resistance to therapy follows. Prior reports have suggested that a relationship may exist between plasma fibrinogen levels and response to therapy in SCCL. This study was designed to determine the possible predictive value of the fibrinogen level for tumor response (chemoresistance) in SCCL. Pretreatment fibrinogen levels were correlated with outcome and response to therapy in a cohort of 119 previously untreated patients with SCCL who were admitted to VA Cooperative Study 188. Higher pretreatment fibrinogen levels at diagnosis correlated significantly with more advanced stage of disease at entry (P < 0.001) and with reduced overall survival (P = 0.030). In addition, higher pretreatment fibrinogen levels were correlated significantly with a reduced likelihood of achieving subsequent disease regression with combination chemotherapy (P = 0.005). Because several clinical trials have shown that anticoagulant therapy improves tumor response rates and survival of SCCL, we postulate that tumor cell thrombin generation not only promotes SCCL growth but may also be primarily responsible for both increased fibrinogen levels and for resistance to chemotherapy. These findings provide incentive for studies of thrombin effects on the development of multidrug resistance, and for new clinical trials of more potent and specific inhibitors of thrombin that may further improve tumor response and survival in SCCL.

Carcinoma, Small Cell↗
PubMed1995

Autologous bone marrow transplantation versus chemotherapy in relapsed/refractory non-Hodgkin's lymphoma: estimates of long-term survival from the recent literature.

Long-term survival following chemotherapy or autologous bone marrow transplantation in adults with relapsed/refractory non-Hodgkin's lymphoma was evaluated. English language articles published from January 1, 1988 to September 1, 1993 were obtained from a broad-based MEDLINE search retrieving 3,854 citations regarding therapy for lymphomas. Citations were evaluated using both computer-based evaluation and manual review. Articles were included if they addressed the disease of interest (non-Hodgkin's lymphoma, Working Formulation D-H), the population of interest (adults with either relapsed or refractory disease), and the therapies of interest (chemotherapy or autologous bone marrow transplantation). Articles were excluded if they did not provide convincing information on long-term survival (as evidenced by either survival analysis or individual patient data) or if they reported a small number of patients (N < 15). No randomized trials of the two therapies were found. Nine case series were found reporting on 444 eligible patients receiving chemotherapy; eight were found reporting on 256 patients undergoing autologous marrow transplantation. After weighting by sample size, the mean 3-year survival rate was 25% (95% CI, 20-30%) following chemotherapy and 40% (95% CI, 33-47%) following marrow transplantation. The reporting of potentially relevant prognostic factors was inconsistent among articles. Despite our comprehensive synthesis and evaluation of currently available data, the survival advantage of marrow transplantation in relapsed/refractory non-Hodgkin's lymphoma that we report must be viewed as tentative, given the limitations of the case series data. In addition, establishing the comparability of patients treated with these therapies is made more difficult by the inconsistent reporting of potentially relevant prognostic factors. The results of an international randomized trial of these two therapies is forthcoming and may address some of these shortcomings.

Adult↗
PubMed1995

Studies of possible mechanisms for the effect of urokinase therapy in small cell carcinoma of the lung.

Urokinase-type plasminogen activator has been administered by other investigators to patients with small cell carcinoma of the lung (SCCL) in an attempt to induce lysis of fibrin that is known to exist in the connective tissue stroma of this tumour type and that may support tumour growth. To study the fate of infused urokinase in this disease, a biopsy of a scalp metastasis was obtained from a patient with SCCL (entered on a phase I clinical trial of urokinase plus combination chemotherapy) immediately following urokinase infusion during the fourth course of therapy a time when this tumour mass had decreased to approximately 25% of its original size. Immunohistochemical procedures revealed abundant stromal fibrin in accord with previous observations from this laboratory. By contrast, urokinase, that is not a feature of small cell tumour cells, was present on the tumour cells in this specimen. Urokinase infusion was associated with a rapid increase in the amount of this enzyme associated with isolated peripheral blood monocytes. These results are consistent with uptake of infused urokinase onto monocytes and possibly tumour cells. It is postulated that substantial tumour fibrinolysis may not accompany such therapy and that urokinase, or its amino terminal fragment that bears the growth factor domain of this molecule, may bind to and alter the growth of the tumour cells.

Aged↗
PubMed1995

Anti-body-dependent cellular cytotoxicity (ADCC) function of peripheral blood polymorphonuclear neutrophils (PMN) after autologous bone marrow transplantation (ABMT).

Rapid recovery of the number and function of polymorphonuclear neutrophils (PMN) is critical to recovery from bone marrow transplantation. Although it is relatively easy to measure PMN number recovery, the evaluation of the functional recovery of these cells has not been adequately examined. The ability of peripheral blood PMNs to perform antibody-dependent cellular cytotoxicity (ADCC) was assessed in 25 patients undergoing autologous bone marrow transplantation (ABMT). PMNs were evaluated at a single cell level for ADCC function as measured by their ability to form plaques in antibody-sensitized ox erythrocyte (oxE) monolayers. The PMNs demonstrated low or absent ADCC function in the first week after completion of high-dose chemotherapy, regardless of primary diagnoses or myeloablative regimens. Although recovery to a neutrophil count of 500/microliters was prolonged in patients with AML (mean 40.2 days; range 25-67 days), functional activity of PMNs appeared much earlier (mean 19.6 +/- 6.1 days; range 2-65 days) in this group of patients compared to the group of patients with other diagnoses in which recovery to a neutrophil count of 500/microliters and the recovery of functional activity of PMNs occurred at roughly the same time. This single cell assay provided a useful method for determining ADCC functional ability of recovering PMNs post-BMT since few cells were required for each assay. This approach may also be useful in determining optimal timing of immune therapies post-ABMT, relying on myeloid cells as effector cells.

Adult↗
PubMed1992

Prudent strategies for elective red blood cell transfusion.

OBJECTIVE: To review the literature on the appropriateness of red blood cell transfusion and current physician practice, with emphasis on the physiologic and symptomatic implications of elective transfusion in the treatment of anemia. DATA SOURCES: Studies on the therapeutic use of red blood cell transfusion were identified through a search of MEDLINE (1966 to the present) and through a manual review of bibliographies of identified articles. In addition, evidence was solicited from selected experts in the field and recent consensus panels that have developed transfusion guidelines. DATA SYNTHESIS: No controlled trials of blood transfusion were identified, but data were available on four issues relevant to transfusion practice: current physician practice and evidence for excessive use of red blood cell transfusion; physiologic adaptation to anemia; human tolerance of low hemoglobin levels; and strategies for reducing homologous transfusion requirements. CONCLUSIONS: Despite the recent decline in red blood cell use because of concerns about infection, current transfusion practice remains variable because physicians have disparate views about its appropriateness. The remarkable human tolerance of anemia suggests that clinicians can accept hemoglobin levels above 70 g/L (7 g/dL) in most patients with self-limited anemia. In patients with impaired cardiovascular status or with anemias that will not resolve spontaneously, however, the data are insufficient to determine minimum acceptable hemoglobin levels, and therapy must be guided by the clinical situation. Several therapeutic strategies and pharmacologic interventions are available in the perioperative and non-operative settings to further reduce red blood cell use.

Adaptation, Physiological↗
PubMed1992

Clinical trials with anticoagulant and antiplatelet therapies.

Clinical trials of drugs that influence coagulation and fibrinolysis pathways have been undertaken in patients with malignancy because these pathways are capable of influencing malignant progression. The validity of this concept was originally confirmed in experimental animal models of malignancy. Earlier pilot studies in human disease have been succeeded by definitive prospective randomized clinical trials that have revealed heterogeneity of responsiveness to anticoagulant and fibrinolytic agents that may be attributable to differences in mechanisms of interaction of the tumor cells of various types of malignancy with these pathways in vivo. In certain tumor types studied thus far, increased tumor response rates and prolongation of survival have been observed that suggest the possibility that substantial benefit may be realized from this treatment approach in patients with malignancy. In addition, the availability of newer and potentially more effective therapeutic agents holds promise for even greater gains in previously tested tumor types. The ability to design treatment regimens that correspond to defined mechanisms that pertain to specific tumor types should permit future studies to be designed rationally. Current data suggest that anticoagulant and fibrinolytic agents might reasonably be tested in tumor types characterized by the existence of a tumor cell-associated coagulation pathway with thrombin generation and conversion of fibrinogen to fibrin (such as small cell carcinoma of the lung). By contrast, protease inhibitors might reasonably be tested in tumor types characterized by expression of tumor cell plasminogen activators. Expansion of current views on the possible role of antithrombic drugs in cancer therapy is justified. For example, antithrombotic drugs classified as non-steroidal anti-inflammatory agents may inhibit carcinogenesis while polyanionic drugs with anticoagulant properties, such as suramin and heparin, may inhibit growth factor interactions with cells. Intriguing new opportunities clearly exist for interactions between clinical and basic investigators that may provide both novel biologic insights and improved patient care.

Anticoagulants↗