The purpose of this study is to evaluate the ability of the T-SPOT.CMV assay to determine immune competence against CMV infection in stem cell transplantation.

To determine the utility of the T-SPOT.CMV assay used before transplantation to determine immune competence against subsequent CMV reactivation and to determine the utility of the T-SPOT.CMV assay used after transplantation to determine immune competence against subsequent CMV reactivation.

In this prospective, non-randomized, observer-blind observational study, up to 200 patients who meet the study's eligibility criteria will be enrolled at up to 20 study centers. Enrollment will be actively managed by the sponsor.

Blood samples will be collected up to 14 days before transplantation, and then at 2-week intervals for the 6 months after the transplant procedure.

Study duration: 15 months: 9 months to enroll all patients, with 6 months (182 days) of participation for each patient.

Inclusion Criteria:

1. Age ≥18 years.
2. Patients who will undergo one of the following types of allogeneic transplantation: matched related donor, matched or mismatched unrelated donor, haploidentical, or cord blood.
3. Patients must be seropositive for CMV prior to transplantation, regardless of donor seropositivity.
4. Institutional Review Board (IRB)-approved written Informed Consent and privacy agreement per national regulation (e.g., Health Insurance Portability and Accountability Act [HIPAA] for sites in the USA) must be obtained from the patient or the patient's legally authorized representative prior to any study-specific procedures.
5. Patients must be considered suitable for the study by the Investigator.

Exclusion Criteria:

• 1. Patients with a known active CMV reactivation within 1 month prior to enrollment or during the study's pre-transplant screening period.

  2. Patients who have received any antiviral therapy active against CMV other than acyclovir and valacyclovir (i.e., foscarnet, ganciclovir, valganciclovir, or cidofovir) during the month prior to enrollment.

  3. Patients who have previously received or are planning to receive a CMV vaccine.

  4. Patients who are known to be hepatitis B, hepatitis C, or human immunodeficiency virus (HIV) positive.

  5. Patients who are known to have a clinically significant medical or psychiatric condition considered a high risk for participation in an investigational study.

  6. Patients who are participating in or plan to participate in CMV-related drug or vaccine studies.

Patients enrolled in this study will be men or women aged 18 years or older with positive CMV serostatus (R+) who are candidates for allogeneic HSCT.

The patients enrolled are intended to be representative of those who would be anticipated to have T SPOT.CMV testing when it is used in routine clinical practice. Enrollment will be actively managed by the sponsor.