∙ Patients are eligible for inclusion if all of the following criteria are met:

• Age ≥ 18 years

• Planned to undergo alloSCT for one of the following haematological malignancies: acute leukaemia (including myeloid and/or lymphoid lineage or biphenotypic), myelodysplastic syndrome, chronic lymphocytic leukaemia (CLL), B-cell non-Hodgkin lymphoma (NHL) and plasma cell myeloma

• Physician preference for a non-myeloablative conditioning regimen

• Available 10/10 HLA-matched related or unrelated haematopoietic stem cell donor

• Transplantation to be performed from a peripheral blood stem cell source

• Adequate renal and hepatic function at screening as follows:

‣ Calculated creatinine clearance \>50ml/min as measured by Cockroft Gault formula

⁃ AST and ALT ≤ 3.0 x ULN

⁃ Bilirubin ≤ 1.5 x ULN (except patients with Gilbert's Syndrome)

• Able to tolerate oral medications

• Disease status at the time of transplantation as follows:

‣ Acute leukaemia in complete morphologic remission

⁃ Myelodysplastic syndrome with less than 10% bone marrow blasts

⁃ CLL in complete remission (CR), partial response (PR) or PR with lymphocytosis

⁃ NHL in CR or PR

⁃ Myeloma in CR, very good partial response (VGPR) or PR within 3 months of prior autologous stem cell transplantation as part of a tandem auto-allo transplant approach

• ECOG performance status 0-1