Study to Assess the Safety and Immunogenicity of GlaxoSmithKline (GSK) Biologicals' Herpes Zoster Subunit (HZ/su) Vaccine in Adults Aged 18 Years and Older With Blood Cancers

Inclusion Criteria:

* Subjects who the investigator believes can and will comply with the requirements of the protocol.
* Written informed consent obtained from the subject.
* A male or female, aged 18 years or older at the time of study entry.
* Subject who has been diagnosed with one or more haematologic malignancies prior to the first vaccination and who is receiving, is scheduled to receive or has just finished immunosuppressive cancer therapy to treat this condition.
* Life expectancy greater than or equal to 12 months, as assessed by the investigator.
* Female subjects of non-childbearing potential may be enrolled in the study.

  * Non-childbearing potential is defined as pre-menarche, current tubal ligation, hysterectomy, ovariectomy or post-menopause.
* Female subjects of childbearing potential may be enrolled inthe study, if the subject:

  * has practiced adequate contraception for 30 days prior to vaccination, and
  * has a negative pregnancy test on the day of vaccination, and
  * has agreed to continue adequate contraception during the entire treatment period and for 2 months after completion of the vaccination series.

Exclusion Criteria:

* Subject diagnosed with chronic lymphocytic leukaemia (CLL) who is receiving only oral cancer therapy (subject receiving intra-venous cancer therapy for CLL or intra-venous cancer therapy in combination with oral therapy may be enrolled).
* Subject receiving radiotherapy alone as treatment for his/her haematologic malignancy.
* Planned haematopoietic stem cell transplant (HCT) during the study period. (If a HCT occurred prior to enrolment in the study, the subject may not receive study vaccine until at least 50 days after the transplant procedure).
* Human immunodeficiency virus (HIV) infection by clinical history.
* Use of any investigational or non-registered product other than the study vaccine within 30 days preceding the first dose of study vaccine/placebo, or planned use during the study period. However, the investigational use of a registered product to treat the subject's underlying disease, is allowed.
* Previous vaccination against HZ or varicella within the 12 months preceding the first dose of study vaccine/placebo.
* Planned administration during the study of a HZ or varicella vaccine (including an investigational or non-registered vaccine) other than the study vaccine.
* Occurrence of a varicella or HZ episode by clinical history within the 12 months preceding the first dose of study vaccine/placebo.
* History of any reaction or hypersensitivity likely to be exacerbated by any component of the vaccine.
* Administration or planned administration of a live vaccine in the period starting 30 days before the first dose of study vaccine and ending 30 days after the last dose of study vaccine.
* Administration or planned administration of a non-replicating vaccine within 8 days prior to or within 14 days after either dose of study vaccine.
* Pregnant or lactating female.
* Female planning to become pregnant or planning to discontinue contraceptive precautions before Month 3 (i.e., 2 months after the last dose of study vaccine/placebo).