Ganciclovir effectively prevents cytomegalovirus (CMV) disease in the first 100 days after allogeneic hematopoietic stem cell transplantation (HSCT), but lateonset CMV disease is increasingly observed. We designed a prospective cohort study to define the incidence and risk factors for late CMV infection in patients who undergo HSCT. CMV-seropositive patients were studied prospectively for CMV infection (quantitative pp65 antigenemia, quantitative CMV-DNA, blood culture), T-cell immunity (CMV-specific CD4 ؉ T-helper and CD8 ؉ cytotoxic Tlymphocyte responses, CD4 and CD8 Tcell count, absolute lymphocyte count), and other transplantation-related factors. Univariate and multivariable analyses were used to assess the risk for late CMV infection and disease and to assess overall survival. Late CMV disease developed in 26 of 146 (17.8%) patients a median of 169 days after transplantation (range, 96-784 days); the mortality rate was 46%. Thirty-eight percent of patients surviving late disease had a second episode a median of 79 days after the first episode. At 3 months after transplantation, preceding detection of CMV pp65 antigenemia, CD4 T-cell counts lower than 50 cells/ mm 3 , postengraftment absolute lymphopenia levels lower than 100 lymphocytes/mm 3 , undetectable CMV-specific T-cell responses, and graft-versus-host disease (GVHD) were associated with late CMV disease or death. After 3 months, continued detection of pp65 antigenemia or CMV DNA in plasma or peripheral blood leukocytes and lymphopenia (fewer than 300 lymphocytes/mm 3 ) were strong predictors of late CMV disease and death. In conclusion, CMV viral load, lymphopenia, and CMV-specific T-cell immunodeficiency are predictors of late CMV disease and death after allogeneic stem cell transplantation. Prevention strategies should be targeted at patients in whom CMV reactivated during the first 3 months and those with poor CMV-specific immunity or low CD4 counts. (Blood. 2003;101: 407-414)

To determine whether cytomegalovirus (CMV) antigenemiaguided ganciclovir treatment may be as effective, may require less treatment, and thus may cause less marrow toxicity than ganciclovir administered at engraftment, 226 marrow transplant recipients were randomized at engraftment to receive placebo (antigenemia-ganciclovir group) or ganciclovir (ganciclovir group) until day 100 in a double-blind study. In patients with antigenemia of 3 or more positive cells in 2 slides and/or viremia, study drug was discontinued and ganciclovir was started for at least 3 weeks or until negative CMV antigenemia and resumed only if antigenemia recurred. More patients in the antigenemia-ganciclovir group developed CMV disease before day 100 after transplantation compared with the ganciclovir group (14% v 2.7%, P = .002). Of the 16 patients with CMV disease before day 100 in the antigenemia-ganciclovir group, 10 (8.8%) had disease before or during the first episode of antigenemia and 6 (5.3%) developed disease after discontinuation of ganciclovir. Untreated low-grade antigenemia progressed to CMV disease in 19% of patients with grade 3–4 compared with 0% of patients with grade 0–2 acute graft-versus-host disease (P = .04). There was no significant difference in CMV disease by day 180 after transplantation and thereafter. CMV-related death, transplant survival, and neutropenia were not significantly different between the groups. In the ganciclovir group, more invasive fungal infections occurred (P = .03) and more ganciclovir was used (P <.0001). Thus, delaying the start of ganciclovir until highgrade antigenemia and discontinuing ganciclovir based on negative antigenemia results in more CMV disease by day 100 than ganciclovir administered at engraftment. However, ganciclovir at engraftment is associated with more early invasive fungal infections and more late CMV disease resulting in similar survival rates.

MSL-109 is a monoclonal antibody specific to the cytomegalovirus (CMV) glycoprotein H with high neutralizing capacity. In a prospective, randomized, double-blind study, allogeneic hematopoietic stem cell transplantation (HSCT) recipients with positive donor and/or recipient serology for CMV before transplantation received either 60 mg/kg MSL-109 (n = 59), 15 mg/kg MSL-109 (n = 60), or placebo (n = 60) intravenously every 2 weeks from day -1 until day 84 after transplantation. CMV pp65 antigenemia, CMV-DNA load in plasma, and viremia by culture were tested weekly. Primary end points were development of pp65 antigenemia at any level and/or viremia for which ganciclovir was given. There was no statistically significant difference in CMV pp65 antigenemia or viremia among patients in the 60-mg group (pp65 antigenemia, 47%; viremia, 15%), the 15-mg group (52%; 23%), and the placebo group (45%; 17%). There was also no difference in maximum levels of pp65 antigenemia, time to clearance of pp65 antigenemia after start of ganciclovir, CMV disease, invasive bacterial and fungal infections, time to neutrophil and platelet engraftment, acute graft-versus-host disease, days of hospitalization, and overall survival rate among the 3 groups. However, a subgroup analysis of CMV-seronegative recipients with a seropositive donor (D+/R-) showed a transiently improved survival rate by day 100 in MSL-109 recipients (mortality: 60-mg group, 1/13; 15-mg group, 1/12; placebo group, 6/10 [P = .02 for 60-mg versus placebo groups; P = .08 for 15-mg versus placebo groups]); by the end of follow-up, the difference was no longer statistically significant. The improved survival rate in D+/R- patients could not be attributed to a reduction in CMV disease; however, MSL-109 was associated with improved platelet engraftment and less grade III to IV acute graft-versus-host disease in this subgroup. In a subgroup analysis of CMV-seropositive recipients of MSL-109 (D+/R+ and D-/R+), overall mortality was increased compared to that of the placebo group (P = .12 for the 60-mg versus placebo groups, P = .05 for the 15-mg versus placebo groups, and P = .04 for the dose levels combined versus placebo). MSL-109 was well tolerated and no immune response to the drug was observed. Thus, MSL-109 was safe but did not reduce CMV infection in allogeneic HSCT recipients. The transient survival advantage seen early after transplantation in CMV D+/R- patients and the negative effect on survival in seropositive patients remain unexplained. Thus, there is no evidence that MSL-109 is beneficial in CMV-seropositive HSCT recipients.

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