The main aim of the study is to demonstrate that, by avoiding inappropriate antiviral therapy during LTV prophylaxis, transplant patients will suffer of lower antiviral-drug-related toxicity. A monitoring strategy able to identify true episodes of HCMV productive infection during LTV prophylaxis will lead to a lower rate of inappropriate antiviral therapy and drug-related toxicity without an increased risk of HCMV disease. conditions: Cytomegalovirus Infections conditions: Cytomegalovirus Viremia conditions: Hematopoietic Stem Cell Transplantation studyType: INTERVENTIONAL phases: NA allocation: RANDOMIZED interventionModel: PARALLEL primaryPurpose: DIAGNOSTIC masking: NONE count: 140 type: ESTIMATED name: Determination of HCMV DNA in plasma after DNAse digestion. name: Determination of HCMV DNA in blood or plasma. measure: - Proportion of patients with positive HCMV DNAemia developing antiviral drug-related toxicity. measure: Proportion of patients developing HCMV DNAemia during LTV prophylaxis. measure: Proportion of patients developing HCMV disease within day 100 and between day 100 and 360 from transplant (key secondary endpoint) measure: Proportion of patients stopping LTV prophylaxis and shifting to GCV/VGCV/FOS therapy. measure: Proportion of patients requiring GCV/VGCV/FOS therapy between day 100 and 360. measure: Proportion of patients with persisting HCMV DNAemia. measure: Proportion of patients developing neutropenia between day 100 and 360. measure: Proportion of patients developing HCMV-specific T-cell response at day 100, 180, and 360. measure: Proportion of patients developing LTV-resistant HCMV strains. measure: Cumulative incidence of acute or chronic GvHD. measure: Transplant related mortality (TRM), underlying disease relapse, and 1-year survival. sex: ALL minimumAge: 18 Years stdAges: ADULT stdAges: OLDER_ADULT facility: ASST-Spedali Civili status: RECRUITING city: Brescia state: BS country: Italy name: Michele Malagola, MD role: CONTACT lat: 45.53558 lon: 10.21472 facility: Fondazione IRCCS Policlinico San Matteo status: RECRUITING city: Pavia state: PV zip: 27100 country: Italy name: Daniele Lilleri, MD role: CONTACT phone: +39 0382 502420 email: d.lilleri@smatteo.pv.it name: Irene Cassaniti, PhD role: CONTACT phone: +39 0382 502420 email: i.cassaniti@smatteo.pv.it lat: 45.19205 lon: 9.15917 facility: ASST-Ospedale Papa Giovanni XXIII status: NOT_YET_RECRUITING city: Bergamo country: Italy name: Alessandra Algarotti, MD role: CONTACT lat: 45.69601 lon: 9.66721 facility: IRCCS Azienda Ospedaliero-Universitaria di Bologna status: NOT_YET_RECRUITING city: Bologna country: Italy name: Francesca Bonifazi, MD role: CONTACT lat: 44.49381 lon: 11.33875 facility: ASST Grande Ospedale Metropolitano Niguarda status: NOT_YET_RECRUITING city: Milano country: Italy name: Arianna Pani, MD role: CONTACT lat: 45.46427 lon: 9.18951 facility: Grande Ospedale Metropolitano "Bianchi-Melacrino-Morelli" status: NOT_YET_RECRUITING city: Reggio Calabria country: Italy name: Barbara Loteta, MD role: CONTACT lat: 38.11047 lon: 15.66129 facility: AOU Policlinico Umberto I status: NOT_YET_RECRUITING city: Roma country: Italy name: Corrado Girmenia, MD role: CONTACT lat: 41.89193 lon: 12.51133 facility: Policlinico Universitario Agostino Gemelli status: NOT_YET_RECRUITING city: Roma country: Italy name: Patrizia Chiusolo, MD role: CONTACT lat: 41.89193 lon: 12.51133 hasResults: False