Laura L. Worth

Cord-blood engraftment with ex vivo mesenchymal-cell coculture.

BACKGROUND Poor engraftment due to low cell doses restricts the usefulness of umbilical-cord-blood transplantation. We hypothesized that engraftment would be improved by transplanting cord blood that was expanded ex vivo with mesenchymal stromal cells. METHODS We studied engraftment results in 31 adults with hematologic cancers who received transplants of 2 cord-blood units, 1 of which contained cord blood that was expanded ex vivo in cocultures with allogeneic mesenchymal stromal cells. The results in these patients were compared with those in 80 historical controls who received 2 units of unmanipulated cord blood. RESULTS Coculture with mesenchymal stromal cells led to an expansion of total nucleated cells by a median factor of 12.2 and of CD34+ cells by a median factor of 30.1. With transplantation of 1 unit each of expanded and unmanipulated cord blood, patients received a median of 8.34×10(7) total nucleated cells per kilogram of body weight and 1.81×10(6) CD34+ cells per kilogram--doses higher than in our previous transplantations of 2 units of unmanipulated cord blood. In patients in whom engraftment occurred, the median time to neutrophil engraftment was 15 days in the recipients of expanded cord blood, as compared with 24 days in controls who received unmanipulated cord blood only (P<0.001); the median time to platelet engraftment was 42 days and 49 days, respectively (P=0.03). On day 26, the cumulative incidence of neutrophil engraftment was 88% with expansion versus 53% without expansion (P<0.001); on day 60, the cumulative incidence of platelet engraftment was 71% and 31%, respectively (P<0.001). CONCLUSIONS Transplantation of cord-blood cells expanded with mesenchymal stromal cells appeared to be safe and effective. Expanded cord blood in combination with unmanipulated cord blood significantly improved engraftment, as compared with unmanipulated cord blood only. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00498316.).

A nude mouse model of human osteosarcoma lung metastases for evaluating new therapeutic strategies

The purpose of these studies was to develop a metastatic osteosarcoma nude mouse model to evaluate the in vivo efficacy of new therapeutic compounds. Human SAOS-2 osteosarcoma cells (106 cells) were injected i.v. into nude mice. Cells isolated from a rare pulmonary metastases 6 months later were established (SAOS-LM1) in culture and re-injected. This procedure was repeated 5 additional times to produce the SAOS-LM6 cell line. Visible pulmonary nodules were present 8 weeks following i.v. injection of 106 SAOS-LM6 cells as compared to 17 weeks using SAOS-LM2 cells. Microscopic SAOS-LM6 pulmonary metastases were demonstrated at 6 weeks. Administration of adriamycin on week 9 resulted in regression of macroscopic SAOS-LM6 lung tumors. The ability of the model to be used to evaluate the effectiveness of a biologic agent against microscopic disease was also verified. It was concluded that this model can assess therapeutic efficacy and therefore, may have a role in investigating the potential of novel approaches aimed at eliminating pulmonary metastatic osteosarcoma.

Autologous bone marrow mononuclear cell therapy for severe traumatic brain injury in children.

BACKGROUND:Severe traumatic brain injury (TBI) in children is associated with substantial long-term morbidity and mortality. Currently, there are no successful neuroprotective/neuroreparative treatments for TBI. Numerous preclinical studies suggest that bone marrow-derived mononuclear cells (BMMNCs), their derivative cells (marrow stromal cells), or similar cells (umbilical cord blood cells) offer neuroprotection. OBJECTIVE:To determine whether autologous BMMNCs are a safe treatment for severe TBI in children. METHODS:Ten children aged 5 to 14 years with a postresuscitation Glasgow Coma Scale of 5 to 8 were treated with 6 × 106 autologous BMMNCs/kg body weight delivered intravenously within 48 hours after TBI. To determine the safety of the procedure, systemic and cerebral hemodynamics were monitored during bone marrow harvest; infusion-related toxicity was determined by pediatric logistic organ dysfunction (PELOD) scores, hepatic enzymes, Murray lung injury scores, and renal function. Conventional magnetic resonance imaging (cMRI) data were obtained at 1 and 6 months postinjury, as were neuropsychological and functional outcome measures. RESULTS:All patients survived. There were no episodes of harvest-related depression of systemic or cerebral hemodynamics. There was no detectable infusion-related toxicity as determined by PELOD score, hepatic enzymes, Murray lung injury scores, or renal function. cMRI imaging comparing gray matter, white matter, and CSF volumes showed no reduction from 1 to 6 months postinjury. Dichotomized Glasgow Outcome Score at 6 months showed 70% with good outcomes and 30% with moderate to severe disability. CONCLUSION:Bone marrow harvest and intravenous mononuclear cell infusion as treatment for severe TBI in children is logistically feasible and safe.

Clofarabine ± Fludarabine with Once Daily i.v. Busulfan as Pretransplant Conditioning Therapy for Advanced Myeloid Leukemia and MDS

Although a combination of i.v. busulfan (Bu) and fludarabine (Flu) is a safe, reduced-toxicity conditioning program for acute myelogenous leukemia/myelodysplastic syndromes (AML/MDS), recurrent leukemia posttransplantation remains a problem. To enhance the conditioning regimens antileukemic effect, we decided to supplant Flu with clofarabine (Clo), and assayed the interactions of these nucleoside analogs alone and in combination with Bu in Bu-resistant human cell lines in vitro. We found pronounced synergy between each nucleoside and the alkylator but even more enhanced cytotoxic synergy when the nucleoside analogs were combined prior to exposing the cells to Bu. We then designed a 4-arm clinical trial in patients with myeloid leukemia undergoing allogeneic stem cell transplantation (allo-SCT). Patients were adaptively randomized as follows: Arm I-Clo:Flu 10:30 mg/m(2), Arm II-20:20 mg/m(2), Arm III-30:10 mg/m(2), and Arm IV-single-agent Clo at 40 mg/m(2). The nucleoside analog(s) were/was infused over 1 hour once daily for 4 days, followed on each day by Bu, infused over 3 hours to a pharmacokinetically targeted daily area under the curve (AUC) of 6000 μMol-min ± 10%. Fifty-one patients have been enrolled with a minimum follow-up exceeding 100 days. There were 32 males and 19 females, with a median age of 45 years (range: 6-59). Nine patients had chronic myeloid leukemia (CML) (BC: 2, second AP: 3, and tyrosine-kinase inhibitor refractory first chronic phase [CP]: 4). Forty-two patients had AML: 14 were induction failures, 8 in first chemotherapy-refractory relapse, 7 in untreated relapse, 3 in second or subsequent relapse, 4 were in second complete remission (CR), and 3 in second CR without platelet recovery (CRp), 2 were in high-risk CR1. Finally, 1 patient was in first CRp. Graft-versus-host disease (GVHD) prophylaxis was tacrolimus and mini-methorexate (MTX), and those who had an unrelated or 1 antigen-mismatched donor received low-dose rabbit-ATG (Thymoglobulin™). All patients engrafted. Forty-one patients had active leukemia at the time of transplant, and 35 achieved CR (85%). Twenty of the 42 AML patients and 5 of 9 CML patients are alive with a projected median overall survival (OS) of 23 months. Marrow and blood (T cell) chimerism studies at day +100 revealed that both in the lower-dose Clo groups (groups 1+2) and the higher-dose Clo groups (groups 3+4), the patients had a median of 100% donor (T cell)-derived DNA. There has been no secondary graft failure. In the first 100 days, 1 patient died of pneumonia, and 1 of liver GVHD. We conclude that (1) Clo ± Flu with i.v. Bu as pretransplant conditioning is safe in high-risk myeloid leukemia patients; (2) clofarabine is sufficiently immunosuppressive to support allo-SCT in myeloid leukemia; and (3) the median OS of 23 months in this high-risk patient population is encouraging. Additional studies to evaluate the antileukemic efficacy of Clo ± Flu with i.v. Bu as pretransplant conditioning therapy are warranted.

Growth suppression of established human osteosarcoma lung metastases in mice by aerosol gene therapy with PEI-p53 complexes

Lung metastases are a frequent complication of osteosarcoma and a treatment that would reduce the severity of this complication would be of great benefit to patients. We have used a formulation consisting of polyethyleneimine (PEI) and a p53 gene administered in aerosol to treat established lung micrometastases as a model of human osteosarcoma in nude mice. The SAOS-LM6 cell line, a metastatic derivative of the p53 null SAOS-2 line, expresses high levels of p53 protein after in vitro transfection with PEI– p53 complexes as determined by ELISA, and transfection with both p53 wt and the p53 variant, p53 -CD(1–366) in vitro , results in a marked inhibition of SAOS-LM6 cell proliferation. Aerosol delivery of plasmid DNA containing either the p53 gene or a p53-CD(1–366) variant gene formulated with PEI to mice resulted in highly significant reductions in the numbers and size of tumors ( P <.001), the total number of tumor foci in the lungs ( P <.001) and the size of individual tumor nodules in treated animals compared to untreated, PEI only–treated and PEI–CAT–treated control animals. The different tissues examined did not reveal any signs of toxicity or inflammation after repeated exposure to PEI–DNA. The aerosol delivery of PEI-based formulations of p53 or synthetic p53 variant genes represents a promising new strategy for the treatment of established human osteosarcoma lung metastases. The noninvasive nature of aerosol delivery coupled with low toxicity also make this therapeutic approach potentially appropriate for combination therapy with either radio- or chemotherapy. Cancer Gene Therapy (2001) 8, 619–627.

Individualizing high-dose oral busulfan: Prospective dose adjustment in a pediatric population undergoing allogeneic stem cell transplantation for advanced hematologic malignancies

We investigated whether adjusting the oral busulfan (BU) dosage on the basis of early pharmacokinetic data to achieve a targeted drug exposure could reduce transplant-related complications in children with advanced hematologic malignancies. Twenty-five children received a preparative regimen consisting of thiotepa (250 mg/m2 i.v. daily for 3 days), BU (40 mg/m2 per dose p.o. every 6 h for 12 doses), and cyclophosphamide (60 mg/kg i.v. daily for 2 days) and then underwent allogeneic stem cell transplantation. Busulfan clearance and area under concentration time-curve (AUC) were determined after the first dose using a one-compartment pharmacokinetic (PK) model with first-order absorption. The initial PK analysis was successfully completed after the first BU dose in 21 patients (84%). A final AUC of 1000–1500 μm × min/dose was targeted and subsequent doses were modified as necessary to achieve this value. Fourteen of the 25 patients (56%) required dose adjustment. Follow-up PK analysis was completed in 21 patients and 16 of these achieved the targeted BU exposure for the course of therapy. Interpatient variability in BU clearance was high (up to five-fold). The most frequent regimen-related toxicities were cutaneous and gastrointestinal (stomatitis and diarrhea). Only one patient developed hepatic veno-occlusive disease. Our study demonstrates the feasibility of adjusting the oral BU dose in individual pediatric patients. Although toxicity associated with BU seemed to be reduced, this conclusion is tempered by the fact that the overall regimen-related toxicity (RRT) remains substantial and reflected the effects of all agents used in the preparative regimen. Bone Marrow Transplantation (2000) 26, 463–470.

Increased Fas Expression Reduces the Metastatic Potential of Human Osteosarcoma Cells

Purpose: The process of metastasis requires the single tumor cell that seeds the metastatic clone to complete a complex series of steps. Identifying factors responsible for these steps is essential in developing and improving targeted therapy for metastasis. Resistance to receptor-mediated cell death, such as the Fas/Fas ligand pathway, is one mechanism commonly exploited by metastatic cell populations. Experimental Design and Results: LM7, a subline of the SAOS human osteosarcoma cell line with low Fas expression, was selected for its high metastatic potential in an experimental nude mouse model. When transfected with the full-length Fas gene (LM7-Fas), these cells expressed higher levels of Fas than the parental LM7 cells or LM7-neo control-transfected cells. These cells were also more sensitive to Fas-induced cell death than controls. When injected intravenously into nude mice, the LM7-Fas cell line produced a significantly lower incidence of tumor nodules than control cell lines. Lung weight and tumor nodule size were also decreased in those mice injected with LM7-Fas. Levels of Fas were quantified in osteosarcoma lung nodules from 17 patients. Eight samples were Fas negative, whereas the remaining 9 were only weakly positive compared with normal human liver (positive control). Conclusions: Our results demonstrate that altering Fas expression can impact the metastatic potential of osteosarcoma cells. We conclude that the increase of Fas on the surface of the LM7 osteosarcoma cells increased their sensitivity to Fas-induced cell death in the microenvironment of the lung, where Fas ligand is constitutively expressed. Thus, loss of Fas expression is one mechanism by which osteosarcoma cells may evade host resistance mechanisms in the lung, increasing metastatic potential. Fas may therefore be a new therapeutic target for osteosarcoma.

Corruption of the Fas Pathway Delays the Pulmonary Clearance of Murine Osteosarcoma Cells, Enhances Their Metastatic Potential, and Reduces the Effect of Aerosol Gemcitabine

Purpose: Pulmonary metastases continue to be a significant problem in osteosarcoma. Apoptosis dysfunction is known to influence tumor development. Fas (CD95, APO-1)/FasL is one of the most extensively studied apoptotic pathways. Because FasL is constitutively expressed in the lung, cells that express Fas should be eliminated by lung endothelium. Cells with low or no cell surface Fas expression may be able to evade this innate defense mechanism. The purpose of these studies was to evaluate Fas expression in osteosarcoma lung metastases and the effect of gemcitabine on Fas expression and tumor growth. Experimental Design and Results: Using the K7M2 murine osteosarcoma model, Fas expression was quantified using immunohistochemistry. High levels of Fas were present in primary tumors, but no Fas expression was present in actively growing lung metastases. Blocking the Fas pathway using Fas-associated death domain dominant-negative delayed tumor cell clearance from the lung and increased metastatic potential. Treatment of mice with aerosol gemcitabine resulted in increased Fas expression and subsequent tumor regression. Conclusions: We conclude that corruption of the Fas pathway is critical to the ability of osteosarcoma cells to grow in the lung. Agents such as gemcitabine that up-regulate cell surface Fas expression may therefore be effective in treating osteosarcoma lung metastases. These data also suggest that an additional mechanism by which gemcitabine induces regression of osteosarcoma lung metastases is mediated by enhancing the sensitivity of the tumor cells to the constitutive FasL in the lung.

Infections in 100 cord blood transplantations: Spectrum of early and late posttransplant infections in adult and pediatric patients 1996-2005

Cord blood-derived stem cells are successfully used in the treatment of cancer and congenital disorders in children. This alternative source of stem cells is also explored for adult cancer patients with limited donor options. However, delayed engraftment, prolonged neutropenia, secondary graft loss, and graft-versus-host disease (GVHD) in recipients of cord blood transplantation (CBT) make opportunistic infections a serious concern. We evaluated the spectrum of infections in adults and children undergoing CBT at our National Cancer Institute-designated comprehensive cancer center. The infection incidence rate ratio (total infection episodes/days at risk [survival after CBT] × 100) was 2.4 times higher in 35 adult patients than in 62 children, especially in adults with neutropenia (3 × higher) and GVHD (1.9 × higher). Ninety-two percent of fungal infection episodes occurred within 100 days after transplantation; half of these infections occurred in the first 30 days after CBT. Most bacterial infections (80%) were also diagnosed in the first 100 days, whereas late (>100 d) post-CBT cytomegalovirus and varicella zoster virus infections occurred only in children with chronic GVHD. Multivariate analysis showed that resolution of lymphocytopenia (≥1000 cells/μL) (hazard ratio [HR] 0.71; p < 0.0001) and successful engraftment (HR 0.20; p < 0.0001) were associated with a low risk of serious infection. Children (HR 0.36; p < 0.0002) with sustained engraftment (HR 0.39; p < 0.004) and those with cancer in remission (HR 0.47; p < 0.007) were less likely to die from infection. More effective measures for surveillance and prevention of late cytomegalovirus and varicella zoster virus infections in children with CBT and chronic GVHD are needed. Abbreviations: BCG = bacilli Calmette-Guèrin, CBT = cord blood transplantation, CMV = cytomegalovirus, GVHD = graft-versus-host disease, HHV = human herpesvirus, HLA = human lymphocyte antigen, HR = hazard ratio, VZV = varicella zoster virus.

Reduced-intensity conditioning using fludarabine, melphalan and thiotepa for adult patients undergoing haploidentical SCT.

Haploidentical SCT (HaploSCT) has been most commonly performed using a myeloablative, TBI-based preparative regimen; however, the toxicity with this approach remains very high. We studied the feasibility of a reduced-intensity conditioning regimen in a phase II clinical trial using fludarabine, melphalan and thiotepa and antithymocyte globulin (ATG) for patients with advanced hematological malignancies undergoing T-cell depleted HaploSCT. Twenty-eight patients were entered in the study. Engraftment with donor-derived hematopoiesis was achieved in 78% of patients after a median of 13 days. Six patients experienced primary graft failure, three out of four tested patients had donor-specific anti-HLA antibodies (DSA) (P=0.001). Toxicity included mostly infections. A total of 21 out of 22 patients with AML/myelodysplastic syndrome (MDS) achieved remission after transplant (16 with relapsed/refractory AML). Five out of the 12 patients (42%) with AML/MDS with <15% BM blasts survived long term as compared with none with more advanced disease (P=0.03). HaploSCT with this fludarabine, melphalan and thiotepa and ATG RIC is an effective, well-tolerated conditioning regimen for patients with AML/MDS with low disease burden at the time of transplant and allowed a high rate of engraftment in patients without DSA. Patients with overt relapse fared poorly and require novel treatment strategies.