Continuing to strengthen FDA's science approach to emerging technologies.

Emerging technologies result when advances and innovation in technology lead to discoveries. Often emerging technologies stimulate novel research in medical product development that contribute to new approaches to manufacturing and can improve the quality of products. By supporting investments in agency coordination, staff training and professional development, regulatory science research, stakeholder engagement, and enhancing opportunities for expert input, the U.S. Food and Drug Administration plays a critical role in translating innovations into novel safe and effective medical products that improve the public health.

Regulation of xenogeneic porcine pancreatic islets.

The use of xenogeneic porcine pancreatic islets has been shown to be a potentially promising alternative to using human allogeneic islets to treat insulin-dependent type 1 diabetes (T1D). This article provides an overview of the existing FDA regulatory framework that would be applied to the regulation of clinical trials utilizing xenogeneic porcine pancreatic islets to treat T1D.

Depletion of L-ascorbic acid alternating with its supplementation in the treatment of patients with acute myeloid leukemia or myelodysplastic syndromes.

PURPOSE: L-ascorbic acid (LAA) modifies the in vitro growth of leukemic cells from approximately 50% of patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS). To test the hypothesis that depletion of LAA, alternating with supplementation to prevent scurvy, would provide therapeutic benefit, a single-arm pilot trial was conducted (ClinicalTrials.gov identifier: NCT00329498). Experimental results: During depletion phase, patients with refractory AML or MDS were placed on a diet deficient in LAA; during supplementation phase, patients received daily intravenous administration of LAA. An in vitro assay was performed pretherapy for LAA sensitivity of leukemic cells from individual patients. RESULTS: Of 18 patients enrolled, eight of 16 evaluable patients demonstrated a clinical response. Responses were obtained during depletion (four patients) as well as during supplementation (five patients) but at a pharmacologic plasma level achievable only with intravenous administration. Of nine patients for whom the in vitro assay indicated their leukemic cells were sensitive to LAA, seven exhibited a clinical response; compared with none of six patients who were insensitive to LAA. CONCLUSIONS: The clinical benefit, along with a conspicuous absence of significant adverse events, suggests that further testing of LAA depletion alternating with pharmacologic dose intravenous supplementation in patients with these and other malignancies is warranted.

Cole-Cole, linear and multivariate modeling of capacitance data for on-line monitoring of biomass.

This work evaluates three techniques of calibrating capacitance (dielectric) spectrometers used for on-line monitoring of biomass: modeling of cell properties using the theoretical Cole-Cole equation, linear regression of dual-frequency capacitance measurements on biomass concentration, and multivariate (PLS) modeling of scanning dielectric spectra. The performance and robustness of each technique is assessed during a sequence of validation batches in two experimental settings of differing signal noise. In more noisy conditions, the Cole-Cole model had significantly higher biomass concentration prediction errors than the linear and multivariate models. The PLS model was the most robust in handling signal noise. In less noisy conditions, the three models performed similarly. Estimates of the mean cell size were done additionally using the Cole-Cole and PLS models, the latter technique giving more satisfactory results.

Biomimetic carbohydrate substrates of tunable properties using immobilized dextran hydrogels.

Glycidylmethacrylate-modified dextran macromers (Dex-GMA) of different degrees of substitution (DS) were synthesized. The elastic modulus of the hydrogels produced using one-component and two-component macromer systems was measured using rheometry. When one macromer of DS 1/10 was used, a hydrogel modulus in the range of 0.2 Pa to 42 kPa was obtained by varying the Dex-GMA concentration from 80 to 200 mg/mL. When a mixture of two macromers of different DS (1/10 and 1/23) was used, a more uniform variation of modulus in the range of 0.4 Pa to 42 kPa was achieved by controlling the ratio of the two macromers. When dextran hydrogels were functionalized with fibronectin and immobilized onto glass substrates, the attachment, spreading, and growth of human aortic smooth muscle cells were modulated by the elastic properties of the dextran matrix. The dextran hydrogel system with tunable mechanical and biochemical properties appears promising for applications in cell culture and tissue engineering.

Adhesion of MC3T3-E1 cells to RGD peptides of different flanking residues: detachment strength and correlation with long-term cellular function.

We synthesized a series of RGD peptides and immobilized them to an amine-functional self-assembled monolayer using a modified maleimide-based conjugate technique that minimizes nonspecific interactions. Using a spinning disc apparatus, a trend in the detachment strength (tau(50)) of RGD peptides of different flanking residues was found: RGDSPK > RGDSVVYGLR approximately RGDS > RGES. Using blocking monoclonal antibodies, cellular adhesion to the peptides was shown to be primarily alpha(v)-integrin-mediated. In contrast, the tau(50) value of the cells on fibronectin (Fn)-coated substrates of similar surface density was 6-7 times higher and involved both alpha(5)beta(1) and alpha(v)beta(3) integrins. Cellular spreading was enhanced on RGD peptides after 1 h when compared to RGE and unmodified substrates. However, no significant differences were observed between the different RGD peptides. Long-term function of MC3T3-E1 cells was also evaluated by measuring alkaline phosphatase (ALP) activity and mineral deposition. Among the four peptides, RGDSPK exhibited the highest level of ALP activity after 11 days and mineralization after 15 days and reached comparable levels as Fn substrates after 15 and 24 days, respectively. These findings collectively illustrate both the advantages and limitations of enhancing cellular adhesion and function by the design of RGD peptides.

Effect of biomaterial surface properties on fibronectin-alpha5beta1 integrin interaction and cellular attachment.

The ability of fibronectin (Fn) to mediate cell adhesion through binding to alpha(5)beta(1) integrins is dependent on the conditions of its adsorption to the surface. Using a model system of alkylsilane SAMs with different functional groups (X=OH, COOH, NH(2) and CH(3)) and an erythroleukemia cell line expressing a single integrin (alpha(5)beta(1)), the effect of surface properties on the cellular adhesion with adsorbed Fn layers was investigated. (125)I-labeled Fn, a modified biochemical cross-linking/extraction technique and a spinning disc apparatus were combined to quantify the Fn adsorption, integrin binding and adhesion strength, respectively. This methodology allows for a binding equilibrium analysis that more closely reflects cellular adhesion found in stable tissue constructs in vivo. Differences in detachment strength and integrin binding were explained in terms of changes in the adhesion constant (psi, related to affinity) and binding efficiency of the adsorbed Fn for the alpha(5)beta(1) integrins (CH(3) approximately NH(2)

Extranodal nasal type NK/T-cell lymphoma: elucidating clinical prognostic factors for risk-based stratification of therapy.

The purpose of this study was to define distinctive clinical features of "nasal" and "nasal-type" NK/T cell lymphomas by assessing prognostic factors. The anatomic definition of extranasal NK/T cell lymphoma has been vague resulting in variable definitions of extranasal sites by different groups. We analysed the clinical behavior of 90 NK/T cell lymphoma patients and attempted to elucidate the prognostic factors for risk-based stratification of therapy. We observed no significant difference between "nasal" and "nasal-type" NK/T cell lymphomas in regards to clinical features and survival using the conventional anatomic classification. We suggest the categorisation of the two subtypes of NK/T cell lymphoma as follows: UNKTL (upper aerodigestive tract NK/T cell lymphoma) including all lymphomas confined to nasal cavity, nasopharynx, and the upper aerodigestive tract and EUNKTL (extra-upper aerodigestive tract NK/T cell lymphoma) group to include all sites other than the UNKTL group. The EUNKTL group in this study had advanced stage at diagnosis, higher LDH, higher IPI score, poorer performance and inferior response to the anthracycline-based chemotherapy with statistical significance. There was a significant difference in survival rate between EUNKTL and UNKTL group (20.0%, 54.0%, respectively, P = 0.0068). More aggressive treatment should be sought for this particular group of patients for EUNKTL patients.

The effect of non-specific interactions on cellular adhesion using model surfaces.

The contribution of non-specific interactions between cells and model functional surfaces was measured using a spinning disc apparatus. These model functional surfaces were created using self-assembled monolayers (SAM) of alkylsilanes terminated with epoxide, carboxyl (COOH), amine (NH(2)), and methyl (CH(3)) groups. These SAMs were characterized using ellipsometry, atomic force microscopy, contact angle goniometry, and X-ray photoelectron spectroscopy to confirm the presence of well-formed monolayers of expected physicochemical characteristics. All substrates also demonstrated excellent stability under prolonged exposure (up to 18 h) to aqueous conditions. The adhesion strength of K100 erythroleukemia cells to the functional substrates followed the trend: CH(3) < COOH approximately epoxide << NH(2). The NH(2) SAM surface exhibited nearly an order of magnitude greater adhesion strength than the other SAMs and this non-specific effect exceeded the adhesion measured when RGD tri-peptides were also immobilized on the surface. These findings illustrate the importance of substrate selection in quantitative studies of peptide-mediated cellular adhesion.

Influential factors for the collection of peripheral blood stem cells and engraftment in acute myeloid leukemia patients in first complete remission.

Although several studies have investigated factors influencing peripheral blood stem cell (PBSC) mobilization in patients with nonmyeloid malignancies in an effort to increase the efficiency of autologous PBSC transplantation (APBSCT), there are very few reports on the efficiency of PBSC mobilization in patients with leukemia. We analyzed the effects of influential variables on successful mobilization and the correlation between infused cell doses and engraftment in acute myeloid leukemia (AML) patients in first complete remission (CR1) who received APBSCT. Between May 1998 and May 2003, 34 patients with AML underwent APBSC collections at our institution. All patients were in CR1 at the time of transplantation. Except for 1 patient, all patients successfully achieved the target CD34(+) cell yield of > or = 2 x 10(6)/kg. Among progenitor cells, the CD34(+) cell dose and the colony-forming unit-granulocyte-macrophage count showed significant correlations with neutrophil and platelet engraftments. The time to neutrophil engraftment was inversely correlated to the number of infused CD34(+) cells (r = -0.67; P < .001), whereas the time to neutrophil engraftment was not significantly correlated with the number of monocytes (r = 0.20; P = .701) or the number of nucleated cells (r = 0.35; P = .062). The time to platelet engraftment was significantly correlated with the dose of infused CD34(+) cells (r = -0.47; P = .012). The univariate analysis showed that more CD34(+) cells per kilogram and more CD34(+) cells per kilogram per day were collected from patients who had a shorter interval (less than 2 months) between diagnosis and PBSC harvest (P = .0111). In conclusion, this study showed that the CD34(+) cell dose was most strongly correlated with a successful engraftment in AML CR1 patients who underwent APBSCT. The proper timing of PBSC collections should be explored to optimize the outcome of APBSCT in AML CR1 patients.

Gefitinib (ZD1839) monotherapy as a salvage regimen for previously treated advanced non-small cell lung cancer.

PURPOSE: A worldwide compassionate-use program has enabled >42,000 patients with advanced non-small cell lung cancer (NSCLC) to receive gefitinib treatment. Here we report the outcome of gefitinib therapy in patients who enrolled in the "Iressa" Expanded Access Program at the Samsung Medical Center. EXPERIMENTAL DESIGN: Patients with advanced or metastatic NSCLC who had progressed after prior systemic chemotherapy and for whom no other treatment option was available were eligible to receive gefitinib treatment as part of the Expanded Access Program. A post hoc assessment of potential prognostic factors for response and survival was performed by multivariate analysis. RESULTS: All 111 evaluable patients had stage IV disease; most patients had a baseline performance status of 2 [n = 52 (47%)] or 3 [n = 18 (16%)] and had received >/=2 prior chemotherapy regimens (56%). The objective response rate was 26%, the disease control rate (measured over >/=8 weeks) was 40%, and the 1-year survival rate was 44%. Adenocarcinoma histology was associated with better response and disease control rates, and a performance status of 0-2 was also associated with a better disease control rate. Both of these factors, as well as female gender, were significantly associated with longer survival. Gefitinib was well tolerated; the most common adverse event was grade 1 skin rash. CONCLUSIONS: Gefitinib demonstrated significant antitumor activity and a favorable tolerability profile in this series of NSCLC patients with poor prognosis.

Trichostatin inhibits the growth of ACHN renal cell carcinoma cells via cell cycle arrest in association with p27, or apoptosis.

We investigated the in vitro effect of trichostatin (histone deacetylase inhibitor) on cell proliferation, cell cycle regulation and apoptosis in renal cell carcinoma cell lines. Trichostatin significantly inhibited the proliferation of all six cell lines examined in dose-dependent manner with IC50 of about 125-250 nM. Trichostatin (72-h incubation) induced a G1 phase arrest in ACHN, Caki-1, Caki-2 and Renca cell lines and a G2-M phase arrest in A498 cells. When we examined the effects of this drug on ACHN cells, trichostatin decreased the levels of CDK4, CDK6, cyclin D1 and cyclin A proteins. p27 protein was increased by trichostatin. In addition, trichostatin markedly enhanced the binding of p27 with CDK2 and CDK4. Furthermore, the activities of CDK2, CDK4- and CDK6-associated kinase were reduced and the lack of the CDK activity was paralleled by increased hypophosphorylation of Rb protein. Trichostatin also induced apoptosis in all the renal cell carcinoma cell lines. Apoptotic process of ACHN cells was associated with the changes of Bcl-2, caspase-9, caspase-3, caspase-7 proteins as well as mitochondria transmembrane potential (deltapsim) loss. Taken together, these results demonstrate that trichostatin inhibits the growth of renal cell carcinoma cells via cell cycle arrest or apoptosis.

Monensin inhibits the growth of renal cell carcinoma cells via cell cycle arrest or apoptosis.

Previously, we showed that monensin, Na+ ionophore, potently inhibited the growth of acute myelogenous leukemia and lymphoma cells. Here, we demonstrate that monensin inhibited the proliferation of renal cell carcinoma cells with IC50 of about 2.5 micro M. Monensin induced a G1 or a G2-M phase arrest in these cells. When we examined the effects of this drug on ACHN cells, monensin decreased the levels of CDK2, CDK6, cdc2, cyclin A and cyclin B1 proteins. p21 and p27 proteins were increased by monensin. In addition, monensin markedly enhanced the binding of p21 with CDK2 and the binding of p27 with CDK6. Furthermore, the activities of CDK2- and CDK6-associated kinase were reduced in association with hypophosphorylation of Rb protein. Monensin also induced the apoptosis in several renal cell carcinoma cells. Apoptotic process of Caki-2 cells was associated with the changes of Bcl-2, Bcl-XL, caspase-9, caspase-3, caspase-7 proteins as well as mitochondria transmembrane potential (DeltaPsim) loss. Taken together, these results demonstrate for the first time that monensin inhibits the growth of renal cell carcinoma cells via cell cycle arrest or apoptosis.

A phase II trial of concurrent chemoradiation therapy followed by consolidation chemotherapy with oral etoposide and cisplatin for locally advanced inoperable non-small cell lung cancers.

We report a phase II study to evaluate the survival rate, response rate and toxicity of concurrent chemoradiation therapy (CCRT) followed by consolidation chemotherapy (CT) with oral etoposide and cisplatin for patients with locally advanced inoperable non-small cell lung cancer (NSCLC). Fifty-four patients with locally advanced inoperable NSCLC who had received no prior therapy were enrolled into this trial between May 1995 and December 2000. Treatment consisted of two cycles of concurrent CT and four cycles of consolidation CT with oral etoposide (50 mg/m2) on days 1-14 during the CCRT courses and on days 1-21 during the consolidation CT courses, plus cisplatin (75 mg/m2 i.v.) on day 1 of a 28-day cycle. Conventional radiotherapy (1.8 Gy/fraction, 63 Gy over 7 weeks) was delivered from day 1 of the CT. Fifty-two patients were evaluable for response. Twelve patients (22%) achieved complete responses, and 32 patients (60%) achieved partial responses, for an overall response rate of 82% with a median duration of response of 9.1 months. Forty-three per cent developed grade 4 haematological toxicity, 11% grade 3 or 4 oesophagitis and 7% grade 3 or 4 lung toxicity. There were two treatment-related deaths, one from radiation pneumonitis and the other from sepsis. After a median follow-up duration of 50 months (range 20-85), the median overall survival time was 15.3 months (95% CI, 9.7-20.8), and the 1-, 2-, 3-, and 5 year overall survival rates were 62, 40, 30 and 16%, respectively. The duration of median progression-free survival was 12.3 months (95% CI, 7.4-17.3), and the 1-, 2-, 3-, and 5-year progression-free survival rates were 47, 40, 29 and 23%, respectively. Thus, concurrent conventional chest radiotherapy with oral etoposide plus cisplatin followed by consolidation CT led to an encouraging survival rate and prolongation of the time to progression, with moderate toxicity in patients with locally advanced inoperable NSCLC.

In vitro bioactivity and degradation behavior of silica xerogels intended as controlled release materials.

Room temperature-processed silica-based sol-gel, termed silica xerogel, is a novel type of controlled release material. As shown previously, these materials are porous, degradable and can release biologically functional molecules in a controlled manner. It was also demonstrated that these materials are biocompatible in vivo. Herein we report on the ability of silica-based xerogels to form a bioactive, apatite-like (AP) surface and the effect of AP surface on the xerogel stability in vitro. Formation of a crystalline, carbonated AP (c-AP) was found on all silica xerogels studied, with or without Ca- and P-oxides. Calcium and phosphate (Ca-P) free xerogels showed long times to Ca-P precipitation and to formation of a detectable AP-layer (up to 2 weeks). In contrast, the times to precipitation were reduced by 2-3 orders of magnitude, and the c-AP layer was formed within 24 h on all Ca-P containing xerogels. Mechanisms of the c-AP formation on these xerogels were similar to those typical for Ca-P based ceramics: dissolution of calcium and phosphate ions, solution oversaturation with respect to AP and subsequent precipitation of bone-like minerals. The presence of the c-AP surface film produced a remarkable surface stabilizing effect: the rates and the amounts of Si release were significantly reduced in comparison to those for xerogels without the film. This evidence of in vitro bioactivity and controlled degradation, combined with previous in vitro and in vivo reports, suggests that silica xerogel is a promising controlled release material.

Tuberculosis in hematopoietic stem cell transplant recipients in Korea.

Hematopoietic stem cell transplantation (HSCT) results in impaired cell-mediated immunity, which subsequently increases the risk of infection from bacterial, fungal, and viral pathogens. Mycobacterial infections are commonly seen in immunodeficient patients, especially in endemic areas. Several series that have reviewed mycobacterial infections in HSCT patients reported incidences varying from less than 0.1% to 5.5%. From February 1996 to July 2003, we retrospectively reviewed records of 295 adult patients who underwent HSCT at Samsung Medical Center, Korea. Mycobacterial infections were diagnosed in 9 (3.1%) of the 295 transplant recipients. The time from HSCT to tuberculosis (TB) infection ranged from 45 days to 165 days posttransplantation. Analysis at the univariate level indicated that a conditioning regimen with total body irradiation (TBI), chronic graft-versus-host disease, and a previous history of TB infection were significant risk factors for the development of TB infection after HSCT. Multivariate analysis revealed that only a previous history of TB infection and TBI increased the risk of TB infection in HSCT patients (relative risk, 4.8 and 12.5, respectively). Isoniazid prophylaxis in HSCT recipients with only radiologic findings suggestive of past inactive TB infection did not significantly alter the incidence of TB infections (P = .236). In conclusion, a previous history of active TB infection and TBI were significant risk factors of TB infection following HSCT, and isoniazid prophylaxis may benefit HSCT recipients with a previous history of active TB infection.

Phase II study of doxorubicin and cisplatin in patients with metastatic hepatocellular carcinoma.

OBJECTIVE: The outcome of systemic chemotherapy in metastatic hepatocellular carcinoma (HCC) patients had been disappointing. Based on the demonstrated antitumor activities and different mechanisms of action and toxicity profiles, we designed a phase II trial of combination therapy with doxorubicin and cisplatin in metastatic HCC patients anticipating a synergistic interaction of the combination. METHODS: From January 1998 to January 2003, 42 consecutive patients with metastatic HCC were accrued. The regimen consisted of doxorubicin 60 mg/m2 delivered as an intravenous infusion over 30 min on day 1, followed by cisplatin 60 mg/m2 infused over 1 h on day 1. The cycle was repeated every 28 days. The objective tumor response was evaluated after two or three courses of chemotherapy. The serum alpha-fetoprotein level was measured at the start of every cycle. RESULTS: In total, 122 cycles of the regimen were administered, with a median of three cycles per patient (range one to eight cycles). The median age of the patients was 45 years (range 19-61 years), and 37 were evaluable for treatment response. The objective response rate was 18.9% (95% CI 8.0-35%) with one complete response and six partial responses. Six patients (16.2%) had stable disease and 24 patients (64.9%) had progression. Median overall survival of 37 patients was 7.3 months (95% CI 5.9-8.6 months). The median time to progression of all evaluable patients was 6.6 months (95% CI 5.4-7.8 months). Of 37 evaluable patients, 12 32.4%, 95% CI 18.0-49.8%) showed more than 50% decrease in AFP level from their baseline AFP and the median time to decrease in AFP by more than 50% was 1.8 months with a range of 0.7-4.7 months. The chemotherapy was well tolerated and the most common grade 3/4 side effects were neutropenia (14.3%), thrombocytopenia (11.9%), and diarrhea (9.5%). CONCLUSION: Combination chemotherapy with doxorubicin and cisplatin in metastatic HCC patients showed modest antitumor activity with relatively tolerable adverse effects. The objective response rate of the regimen was comparable to those found in other phase II trials, but the search for the optimal chemotherapy should be continued.

Intestinal lymphoma: exploration of the prognostic factors and the optimal treatment.

Primary gastrointestinal (GI) lymphoma accounts for 4% to 20% of all non-Hodgkin's lymphomas (NHL), being the most common extranodal site of presentation. However, the optimal management of intestinal lymphoma has not yet been established. During the period of 1994 to 2001, we retrospectively analyzed the clinical features of 67 intestinal lymphoma patients diagnosed according to the Lewin's definitions. The most frequently involved location was ileocecal (35.8%) followed by small bowel (31.3%), large bowel (19.4%), and multiple GI involvement (13.4%). The estimated 5-year overall survival rate was 53%. Out of all treated patients, 49.2% achieved complete response. The advanced stage, poor performance and T-cell phenotype had an adverse prognostic influence on overall survival. In localized diseases (stage 1 and 2), the primary surgical treatment had the most favorable influence on failure-free survival (P < 0.05). The resection of localized intestinal lymphoma may be appropriate as the primary treatment.

Oxaliplatin and UFT combination chemotherapy in patients with metastatic colorectal cancer.

A phase II study was performed to evaluate the clinical efficacy and toxicity of oxaliplatin combined with uracil and tegafur (UFT) in patients with advanced colorectal cancer previously treated with a fluoropyrimidine-based regimen. From January to December 1999, 34 patients were enrolled in this study. Patients received intravenous oxaliplatin 130 mg/m2 on day 1 and daily oral UFT 350 mg/m2 in 3 divided doses for 21 days and repeated every 21 days. Thirty-one of 34 patients were assessable for response and 32 patients for toxicity. Partial response was observed in four patients and stable disease in six patients. The response rate was 12.9% (95% CI, 3.6-29.8%) and median duration of response was 17 weeks. The median overall survival and progression-free survival of all patients were 26 weeks (range, 3-90+ weeks) and 9 weeks (range, 3-56 weeks), respectively. Sensory neuropathy was the most common toxicity, but there was no severe toxicity (>grade II) except for a case of grade III neutropenia. We conclude that oxaliplatin and UFT combination chemotherapy was well tolerated without significant toxicities. The results of this trial will serve as the basis for designing new clinical trials with a different dose or schedule.

A randomized trial of preemptive therapy for prevention of cytomegalovirus disease after allogeneic hematopoietic stem cell transplantation.

We studied the efficacy of two different doses of ganciclovir to prevent cytomegalovirus (CMV) disease in allogeneic hematopoietic stem cell transplantation (HSCT) recipients. We randomly assigned allogeneic HSCT recipients who had CMV infection to receive preemptive ganciclovir therapy with or without induction phase (5 mg/kg twice daily for 1 week). Thirty-two and thirty-six patients were randomized to the standard and the low-dose therapy group, respectively. The median time to CMV antigenemia or viremia clearance was 7 days (3-25 days) in the standard therapy group versus 11 days (3-69 days) in the low-dose therapy group (P = 0.540). The incidence of CMV disease was similar between the two groups (P = 0.366). The Kaplan-Meier estimate of event-free survival by day 180 after HSCT was 76.2% in the standard therapy group versus 66.7% in the low-dose therapy group (P = 0.590). Severe neutropenia (<0.5 x 10(9)/L) was observed in four (12.5%) patients in the standard therapy group versus two (5.6%) patients in the low-dose therapy group (P = 0.314). This study suggests that a low-dose ganciclovir preemptive therapy can be as effective as the standard-dose ganciclovir preemptive therapy for the prevention of CMV disease in allogeneic HSCT recipients.