Cytomegalovirus viral load monitoring after allogeneic bone marrow transplantation in patients receiving antiviral prophylaxis

Cytomegalovirus viral load measurement is a powerful new tool for monitoring of CMV disease; however, the optimal strategy for use is unknown. Weekly plasma CMV viral loads and CMV-related outcomes were monitored in 46 consecutive allogeneic bone marrow transplantation (BMT) recipients receiving standardised antiviral prophylaxis. A total of 412 CMV viral loads were quantitated in the first 100 days post transplantation with 77 positive samples (19%) in 20 patients (43%). No patient with all negative CMV viral load results developed CMV disease. Two of three patients with highly positive CMV viral loads (first positive < or =30 days post transplant, maximum viral load > or =5000 copies/ml, and > or =50% of samples positive) developed CMV disease. A total of 17 patients with positive CMV viral loads, who did not meet the criteria for highly positive, did not develop CMV disease. CMV viral load detection was higher in recipients who were CMV sero-positive. In conclusion, CMV disease did not occur in the setting of a persistently negative CMV viral load. A positive CMV viral load result occurred commonly after allogeneic BMT, even in patients receiving antiviral prophylaxis.     

Second marrow transplantation following high dose busulfan, etoposide, and Ara-C after testicular relapse in a patient with AML]

Prognosis of second marrow transplantation after leukemia relapse is usually gloomy. We report a patient with AML who was successfully treated by the second marrow transplant following high dose busulfan, etoposide, and Ara-C for the testicular relapse after the first marrow transplantation. A 24-year-old man was diagnosed as having acute myeloid leukemia (AML) in September, 1988. In December of 1989 when he was in early relapse after his 2nd remission, he received the first allogeneic BMT from his HLA identical brother after high dose busulfan and cyclophosphamide conditioning. His posttransplant course was uneventful and graft versus host disease was not observed. Three months after BMT, he noticed swelling on right testicle. Leukemic cell infiltration was confirmed by aspiration cytology. The testicular relapse was followed by marrow relapse. After successful remission induction chemotherapy, he received 17.5 Gy testicular irradiation and second marrow transplantation using high dose busulfan, etoposide, and Ara-C conditioning. Although his posttransplant period was complicated by severe mucositis, high fever and bronchopneumonia, hematologic recovery was obtained by 3 weeks after the second transplant. He is now continuing in complete remission 18 months after the second BMT. This case report suggests that the combination of high dose busulfan, etoposide, and Ara-C could be a choice as a conditioning regimen for resistant AML relapsing after BMT.     

Reduced risk of persisting cytomegalovirus pp65 antigenemia and cytomegalovirus interstitial pneumonia following allogeneic PBSCT

In order to evaluate the risk of cytomegalovirus (CMV) associated disease after allogeneic stem cell transplantation (SCT), 158 consecutive patients at risk for infection were analyzed. BMT was performed in 101 patients and peripheral blood stem cell transplantation (PBSCT) in 57 patients. CMV antigenemia was found in 57 cases (56%) after BMT and 27 cases (47%) after PBSCT, respectively. CMV antigenemia resistant to a 14-day course of GCV was found in 26 patients (26%) after BMT but in only four patients (7%) after PBSCT (P < 0.01). Eighteen patients (11%) developed CMV disease, 14 post BMT and four post PBSCT. Lethal CMV-related interstitial pneumonia (CMV-IP) occurred in 13 cases of whom 12 patients were bone marrow recipients (P = 0.04). The subgroup of seronegative patients with a CMV seropositive donor had a significantly lower risk of developing CMV antigenemia, GCV-resistant CMV antigenemia (P < 0.01) and CMV-related disease (P = 0.01). In conclusion, the incidence of persistent CMV antigenemia and CMV-IP was significantly reduced when allogeneic transplantation was performed with peripheral blood stem cells instead of bone marrow. These findings suggest that our previous in vitro data on improved immune reconstitution after allogeneic PBSCT as compared to allogeneic BMT have clinical relevance.     

Prevention of primary transfusion-associated cytomegalovirus infection in bone marrow transplant recipients by the removal of white cells from blood components with high-affinity filters

Summary. A prospective study was carried out to determine whether use of cytomegalovirus (CMV) unscreened red blood cells and platelet concentrates, white blood cell (WBC) depleted with high-efficiency filters, would prevent transfusion-associated (TA) CMV infection in CMV seronegative bone marrow transplant recipients. Blood components were filtered in the bloodcentre under quality control and after filtration residual WBC counts were always below 5 × 10⁶ cells/U. Since 1990, 23 consecutive allogeneic and 37 autologous CMV seronegative marrow transplant recipients, have been transfused with filtered blood components and followed for 6 months for evidence of CMV infection by monitoring culture and CMV serology. None of the patients showed clinical symptoms of CMV infection, and CMV cultures during episodes of fever were always negative. IgM anti-CMV antibodies were negative during the study in all patients. Low titres of IgG anti-CMV antibodies (5-12 relative ELISA units) were found in 24/60 patients during the first month after bone marrow transplantation (BMT), probably due to passive transfer of IgG administered with the platelet transfusions. 3 and 6 months after BMT, 56 and 48 patients respectively were still alive; and CMV serology was negative in all patients. The results show that TA-CMV infection is preventable by filtration of blood through high-efficiency filters in patients undergoing autologous and allogeneic BMT.     

A second unrelated bone marrow transplant: successful quantitative monitoring of mixed chimerism using a highly discriminative PCR-STR system

A second bone marrow transplant (BMT) might be considered as an option in patients with leukaemia with graft failure after BMT. We report the successful treatment of a patient with graft failure by a second stem cell transplant from another unrelated donor. We evaluated the usefulness of an unrelated donor as the source of the second BMT in this clinical setting. In addition to this, a penta PCR-STR system was tested and shown to be sensitive for monitoring of marrow engraftment. The conditioning regimen for the first transplantation consisted of busulfan and cyclophosphamide while anti-thymocyte globulin and CY were used for the second BMT. The patient successfully engrafted at day + 11 after second BMT.     

Kinetics of cytomegalovirus IgG antibody following infusion of a hyperimmune globulin preparation in allogeneic marrow transplant recipients

We investigated prospectively cytomegalovirus (CMV) IgG antibody kinetics following infusion of a CMV hyperimmune globulin preparation in 19 consecutive patients undergoing allogeneic bone marrow transplantation (BMT). CMV IgG against late antigen was measured by enzyme-linked immunosorbent assay. On a prophylactic hyperimmune globulin regimen (100 mg/kg body weight every 20 days), the mean half-life (t1/2) +/- SD of CMV IgG in seronegative patients with seronegative marrow donors was 19.7 +/- 7.9 days after the first infusion on day -7 before BMT, 24.9 +/- 12.5 days after the second infusion on day +13 after BMT, and 19.4 +/- 6.9 days after the third infusion on day +33. The t1/2 in individual patients showed a wide variation ranging from 10.9 to 47.6 days. A therapeutic high-dose hyperimmune globulin regimen (200-400 mg/kg body weight at 4-day intervals) given to five patients resulted in high serum levels of CMV IgG, which were maintained throughout therapy, even in two patients with severe intestinal graft-versus-host disease. The variation of CMV IgG kinetics between individual BMT recipients may contribute to the lack of protection from active CMV infection observed in some patients.     

A second unrelated bone marrow transplant: successful quantitative monitoring of mixed chimerism using a highly discriminative PCR-STR system.

A second bone marrow transplant (BMT) might be considered as an option in patients with leukaemia with graft failure after BMT. We report the successful treatment of a patient with graft failure by a second stem cell transplant from another unrelated donor. We evaluated the usefulness of an unrelated donor as the source of the second BMT in this clinical setting. In addition to this, a penta PCR-STR system was tested and shown to be sensitive for monitoring of marrow engraftment. The conditioning regimen for the first transplantation consisted of busulfan and cyclophosphamide while anti-thymocyte globulin and CY were used for the second BMT. The patient successfully engrafted at day +11 after second BMT.     

Graft-versus-host disease following second syngeneic stem cell transplantation for relapsed chronic myeloid leukemia

 Allogeneic bone marrow transplantation is the only curative treatment for patients with Philadelphia chromosome-positive chronic myeloid leukemia (CML); however, recurrence of disease remains a major cause of treatment failure. A 26-year-old man with chronic myeloid leukemia who had a cytogenetic relapse 49 months after his first syngeneic bone marrow transplant (BMT) and hematologic relapse 23 months thereafter progressed to blast crisis despite treatment with IFN-alpha for 15 months. He underwent a second transplantation in early second blast crisis, 92 months after the first BMT with PBPC from his previous donor. Successful hematological reconstitution occurred. On day 50 after the second transplantation the patient developed a generalized rash, hepatomegaly, and cholestatic signs. Skin and liver biopsy revealed changes compatible with acute graft-versus-host disease (GVHD). Treatment with cyclosporin A (CSA) and prednisone was started, and the GVHD resolved. Fifteen months after PBPC transplantation he had a molecular relapse. Despite discontinuation of CSA, the patient progressed into blast crisis 7 months later. The occurrence of GVHD and disappearance of the BCR-ABL-positive clone suggest that a graft-versus-leukemia (GVL) effect may have been operative for 15 months in a patient given a second syngeneic BMT in blast crisis. Received: May 12, 1998 / Accepted: August 10, 1998     

Cytomegalovirus infection in leucocytes after bone marrow transplantation demonstrated by mRNA in situ hybridization

Summary. Cytomegalovirus (CMV) infection in leucocytes after bone marrow transplantation (BMT) was identified using a ³⁵S-labelled antisense RNA probe specific for CMV immediate early (IE) gene mRNA. 54 patients were examined regularly up to 14 weeks after BMT, 36 after allogeneic BMT and 18 after autologous BMT. Only mononuclear cells with monocyte morphology were CMV IE mRNA positive. The number of CMV positive leucocytes was higher after allogeneic BMT than after autologous BMT ( P =0.006), and in patients with acute graft-versus-host disease (GvHD) II-IV than with GvHD 0-I ( P =0.06). In patients who later developed chronic GvHD, the mean value of CMV infected leucocytes during the first week after BMT was higher than in patients without chronic GvHD ( P =0.034). Patients with symptomatic CMV infection had greater numbers of CMV infected leucocytes during the fourth and fifth week after BMT than patients without CMV disease, but the difference did not reach statistical significance.
CMV infection of monocytes may be an important factor in the early onset of CMV infection and of GvHD.     

Resolution of immune haemolytic anaemia with allogeneic bone marrow transplantation after an unsuccessful autograft

Autologous transplantation of lymphocyte-depleted peripheral blood stem cells (PBSC) has been proposed for treatment of patients with severe autoimmune disease. However, several patients have been reported to achieve only transient remissions. We report on a child with thalassaemia intermedia and immune-mediated haemolytic anaemia, given an autologous lymphocyte-depleted PBSC transplant, who relapsed 7 weeks after transplant. A complete remission, lasting 18 months to date, was obtained with allogeneic bone marrow transplantation (BMT) from an HLA-matched unrelated donor. This experience indicates that, in selected cases, allogeneic BMT may be the treatment of choice for life-threatening autoimmune disease. A graft-versus-autoimmunity effect may favour the eradication of the recipient autoaggressive lymphocytes.     

Risk Factors for Cytomegalovirus Retinitis Following Bone Marrow Transplantation From Unrelated Donors in Patients With Severe Aplastic Anemia or Myelodysplasia

Two cases of cytomegalovirus (CMV) retinitis following bone marrow transplantation (BMT) from unrelated donors are reported. 1 patient had been treated for severe aplastic anemia (SAA) and the other for hypoplastic myelodysplastic syndrome (MDS). Because first line therapy with antithymocyte globulin (ATG) and cyclosporin A (CsA) had failed, BMT was performed following a conditioning regimen of ATG, cyclophosphamide, and total lymphoid irradiation. Treatment for CMV retinitis was successfully carried out with gancyclovir (systemic and intraocular injection), foscarnet, and photocoagulation (Case 1) and gancyclovir and foscarnet (Case 2). Both patients also developed Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD). We compared these 2 cases with 14 SAA patients who did not develop CMV retinitis after BMT using marrow from either HLA-identical siblings (n = 9) or from unrelated donors (n = 5). Unlike the retinitis patients, the latter 5 patients received ATG only once. The retinitis patients had significantly lower CD4+ T-cell levels in their peripheral blood than the 14 patients who did not develop CMV retinitis. We believe that repeated treatment with ATG and transplantation from unrelated donors may lead to immune dysfunction that could increase the likelihood of CMV retinitis, as well as LPD. For such BMT patients, regular ophthalmic examinations and careful testing for CMV antigenemia are recommended.     

Cytomegalovirus: biology, clinical features and methods for diagnosis

Cytomegalovirus (CMV) infections remain a major obstacle to the successful outcome of bone marrow transplantation (BMT). The clinical manifestations of CMV-induced disease are many and varied and may mimic other disease processes commonly seen after BMT. The development of effective strategies for the prevention and treatment of such infections requires an understanding of the life cycle of the virus. In this review we discuss the molecular structure of CMV, the modes of replication and transmission, and the biology of the development of latency and reactivation. The recent availability of potentially effective anti-CMV drugs emphasizes the need for rapid diagnostic techniques which permit the initiation of treatment early in the disease. We review the diagnostic methods in common use and compare the newly developed rapid assays with the standard techniques of viral isolation and serological responses, with particular reference to their use in marrow transplant recipients.     

Successful bone marrow transplantation for severe aplastic anemia following orthotopic liver transplantation: long-term follow-up and outcome

Severe aplastic anemia (SAA) is well described in children following liver transplantation for fulminant hepatic failure (FHF) secondary to non-A, non-B, non-C hepatitis, and is associated with a high mortality rate. Successful immunosuppressive treatment of SAA following liver transplantation has been reported, but death from infectious complications is not uncommon. We report the 8-year follow-up of a 3.5-year-old boy who underwent successful HLA-identical sibling donor bone marrow transplant for SAA 7 months following orthotopic liver transplant for non-A, non-B, non-C hepatitis. His post-bone marrow transplantation course was uneventful with no evidence of liver toxicity. Eight months following BMT he developed renal cell carcinoma metastatic to lymph nodes which was treated surgically. Six years following BMT he developed a mucoepidermoid carcinoma of the parotid gland also treated surgically. Despite these malignancies, he is currently well 8 years following liver and bone marrow transplantation, without signs of GVHD, growth failure or liver graft rejection. This is the first report of long-term follow-up of bone marrow transplantation for SAA following liver transplantation. The occurrence of two subsequent malignancies in this child underscores the need for close follow-up of future similar cases.     

Current concepts on cytomegalovirus infection after liver transplantation

Cytomegalovirus (CMV) is the most common viral pathogen that negatively impacts on the outcome of liver transplantation. CMV cause febrile illness often accompanied by bone marrow suppression, and in some cases, invades tissues including the transplanted allograft. In addition, CMV has been significantly associated with an increased predisposition to allograft rejection, accelerated hepatitis C recurrence, and other opportunistic infections, as well as reduced overall patient and allograft survival. To negate the adverse effects of CMV on outcome, its prevention, whether through antiviral prophylaxis or preemptive therapy, is regarded as an essential component to the medical management of liver transplant patients. Two recent guidelines have suggested that antiviral prophylaxis or preemptive therapy are similarly effective in preventing CMV disease in modest-risk CMV-seropositive liver transplant recipients, while antiviral prophylaxis is the preferred strategy over preemptive therapy for the prevention of CMV disease in high-risk recipients [CMV-seronegative recipients of liver allografts from CMV-seropositive donors (D+/R-)]. However, antiviral prophylaxis has only delayed the onset of CMV disease in many CMV D+/R- liver transplant recipients, and at least in one study, such occurrence of late-onset primary CMV disease was significantly associated with increased mortality after liver transplantation. Therefore, optimized strategies for prevention are needed, and aggressive treatment of CMV infection and disease should be pursued. The standard treatment of CMV disease consists of intravenous ganciclovir or oral valganciclovir, and if feasible, one should also reduce the degree of immunosuppression. In one recent controlled clinical trial, valganciclovir was found to be as effective and safe as intravenous ganciclovir for the treatment of mild to moderate CMV disease in solid organ (including liver) transplant recipients. In this article, the authors review the current state and the future perspectives of prevention and treatment of CMV disease after liver transplantation.     

Lymphocytopenia as an unfavorable prognostic factor in patients with cytomegalovirus infection after bone marrow transplantation

Sixty-three recipients of an allogeneic marrow transplant were screened for the occurrence of cytomegalovirus (CMV) infection and clinical parameters possibly predicting the development of CMV disease in a retrospective study. Blood and urine samples obtained from these patients were screened weekly after bone marrow transplantation (BMT) for the presence of CMV by polymerase chain reaction (PCR) and virus culture technique. Forty-six of the 63 patients studied were found to be CMV-positive by PCR technique in blood and urine samples at a median of 29 days after BMT. In 33 of these 46 patients, CMV could be cultured from urine samples and 16 of the 46 had culture-positive viremia. Twenty-eight of these 46 PCR-positive patients developed CMV disease. Whereas PCR assays showed an optimal negative predictive value and sensitivity for the development of CMV disease, their positive predictive value was 61% and could not be remarkably increased when culture-proven viruria (64%) and viremia (69%) were considered. Acute graft-versus-host disease (GVHD) grade 2 to 4 (P < .05), but not underlying disease, conditioning therapy, or GVHD prophylaxis, was associated with CMV infection. On day +49, a remarkable decrease (P < .001) in the lymphocyte count, as well as in the absolute number of CD4+, CD8+, and CD56+ lymphocytes, occurred only among the patients who later developed CMV disease. The decrease of all of these cell counts, but predominantly the CD4+ T cells, to less than 100/microL on day +49 after BMT showed a very high positive predictive value (100%) for the development of CMV disease in patients with PCR-proven viremia. Persisting CD4 lymphopenia after antiviral therapy was only observed in patients who finally died of CMV disease. Thus, immunophenotyping of the patients after BMT in addition to a highly sensitive virus detection assay might help to identify patients at high risk to develop CMV disease and indicate the need for additional adoptive immunotherapy.     

Cytomegalovirus infection after autologous bone marrow transplantation: occurrence of cytomegalovirus disease and effect on engraftment

Epidemiologic and clinical characteristics of cytomegalovirus (CMV) infection and disease were analyzed retrospectively in 159 autologous marrow transplant recipients. The probability of CMV infection by day 100 after transplant was 22.5% in patients seronegative to CMV before transplant versus 61.1% in seropositive patients (P less than .0001 by logrank test). Multivariate analysis identified positive pretransplant CMV serology as the only definable risk factor for CMV infection (relative risk 1.4, P less than .0001). CMV pneumonia developed in 11 patients at a median time of 100 days after transplant and was fatal in nine cases. CMV pneumonia was associated with significantly decreased probability of survival by day 100 after transplant (relative risk of death of 16.7, P less than .0001). In contrast to earlier reports, CMV infection had no significant effect on the rapidity of platelet or neutrophil recovery after transplant as assessed by time-dependent multivariate analysis. Because the incidence of severe CMV disease is not negligible after autologous marrow transplantation, preventive measures against CMV infection are warranted, as in allogeneic marrow transplantation.     

Management of cytomegalovirus infection and disease in liver transplant recipients

Cytomegalovirus(CMV) is one of the most common viral pathogens causing clinical disease in liver transplant recipients, and contributing to substantial morbidity and occasional mortality. CMV causes febrile illness often accompanied by bone marrow suppression, and in some cases, invades tissues including the transplanted liver allograft. In addition, CMV has been significantly associated with an increased predisposition to acute and chronic allograft rejection, accelerated hepatitis C recurrence, and other opportunistic infections, as well as reduced overall patient and allograft survival. To negate the adverse effects of CMV infection on transplant outcome, its prevention, whether through antiviral prophylaxis or preemptive therapy, is an essential component to the management of liver transplant recipients. Two recently updated guidelines have suggested that antiviral prophylaxis or preemptive therapy are similarly effective in preventing CMV disease in modest-risk CMV-seropositive liver transplant recipients, while antiviral prophylaxis is the preferredstrategy over preemptive therapy for the prevention of CMV disease in high-risk recipients [CMV-seronegative recipients of liver allografts from CMV-seropositive donors(D+/R-)]. However, antiviral prophylaxis has only delayed the onset of CMV disease in many CMV D+/Rliver transplant recipients, and such occurrence of lateonset CMV disease was significantly associated with increased all-cause and infection-related mortality after liver transplantation. Therefore, a search for better strategies for prevention, such as prolonged duration of antiviral prophylaxis, a hybrid approach(antiviral prophylaxis followed by preemptive therapy), or the use of immunologic measures to guide antiviral prophylaxis has been suggested to prevent late-onset CMV disease. The standard treatment of CMV disease consists of intravenous ganciclovir or oral valganciclovir, and if feasible, reduction in pharmacologic immunosuppression. In one clinical trial, oral valganciclovir was as effective as intravenous ganciclovir for the treatment of mild to moderate CMV disease in solid organ(including liver) transplant recipients. The aim of this article is to provide a state-of-the art review of the epidemiology, diagnosis, prevention, and treatment of CMV infection and disease after liver transplantation.     

Hepatitis B virus (HBV) infection and liver disease after allogeneic bone marrow transplantation: a report of 30 cases

Among 145 consecutive patients undergoing bone marrow transplantation (BMT) for leukemia or aplastic anemia. 30 (21%) were found positive for hepatitis B surface antigen (HBsAg) in serum either before or after BMT. Their serologic profile and clinical outcome are described. Nine out of 30 patients were HBsAg positive before BMT: four were chronic carriers and five were found HBsAg+ at transplant. Three of the former and one of the five latter patients remained persistently HBsAg+ after transplant with signs of liver disease; none developed liver failure, indicating that HBsAg positivity is not an absolute contra-indication to BMT. Among the remaining 21 patients. HBsAg was detected early (n = 12) or late (n = 9) after transplant. All 21 cleared the antigen during follow-up and liver disease was either mild and asymptomatic (nine cases) or clinically overt (12 cases), but none had life-threatening liver disease. Several HBV-infected patients were constantly seronegative for antibody to HBcAg even in the presence of active HBV replication. These results show that the serologic pattern of HBV markers in BMT patients is unpredictable. HBV infection was rarely associated with severe hepatitis and HBsAg carriage.     

Successful treatment of CMV retinitis with ganciclovir after allogeneic marrow transplantation

Cytomegalovirus (CMV) infection of the retina is a well recognized complication in patients with the acquired immune deficiency syndrome but is rarely seen after bone marrow transplantation (BMT). Among a variety of drugs ganciclovir so far appears to be the most effective therapy for CMV retinitis, but in previous studies relapses occurred in all patients in whom ganciclovir was interrupted. We report the clinical findings in a 22-year-old BMT recipient who developed bilateral exudative CMV retinitis 64 days after BMT despite prophylactic treatment with high-titer CMV-immunoglobulins and transfusions of CMV-negative blood products and donor bone marrow. During a 12 day course of treatment with 7.5 mg/kg/day of ganciclovir the CMV retinitis improved and viruria ceased on day 4 of therapy. In contrast to the previous reports, CMV retinitis in this patient continued to improve even after ganciclovir was stopped and eventually complete healing of all intraretinal lesions as well as total reconstitution of the visual acuity was achieved. He is now free of disease and without relapse of CMV retinitis more than 1 year after transplantation.     

Randomized study of valacyclovir as prophylaxis against cytomegalovirus reactivation in recipients of allogeneic bone marrow transplants

Oral valacyclovir for cytomegalovirus (CMV) prophylaxis in bone marrow transplantation (BMT) was investigated in a randomized, double-blind, acyclovir-controlled, multicenter clinical trial in recipients of allogeneic BMT who were CMV seropositive (or donor positive) before transplantation and were aged 13 years or older. Patients were randomized before BMT. All initially received intravenous acyclovir (500 mg/m(2)) 3 times daily until day 28 after transplantation or after discharge, then oral valacyclovir (2 g) or acyclovir (800 mg) 4 times daily until week 18 after transplantation. Evidence of CMV infection, CMV disease, and death were documented for 22 weeks. Primary end points were time to CMV infection (detection of CMV in blood, broncho-alveolar lavage) or CMV disease and survival. Preemptive CMV therapy was permitted. Seven hundred twenty-seven patients were evaluable for efficacy. After the administration of intravenous acyclovir, valacyclovir was significantly more effective than oral acyclovir in reducing the incidence of CMV infection. CMV infection or disease developed in 102 (28%) valacyclovir patients, compared with 143 (40%) acyclovir patients (HR, 0.59; 95% CI, 0.46-0.76; P <.0001). Survival did not differ between treatments (76% and 75% in the valacyclovir and acyclovir groups, respectively). The safety of oral valacyclovir was similar to that of high-dose oral acyclovir. Valacyclovir was more effective than acyclovir in preventing CMV reactivation in BMT recipients and showed a similar safety profile. CMV disease incidence was low, and no differences were observed between oral valacyclovir and acyclovir. Survival was similar in each group. Valacyclovir prophylaxis provides a clinically valuable intervention but must be part of an overall strategy for CMV prevention in BMT.