Role of Antibiotic Therapy or Immunoglobulin On iNfections in hAematoLogy Platform Trial (RATIONAL-PT)

This is an adaptive platform study to find out how safe and effective different strategies are in comparison to each other, for preventing infection in patients with blood cancers. It is a comparison between Immunoglobulin and antibiotics use.

This study is being conducted to find out how safe and effective different strategies of infection prevention are in comparison to each other, for preventing infection in patients with blood cancers. The best way to find out this information is to directly compare the effect of different treatment strategies in patients with blood cancers. We want to know how these different treatments impact on your health and your use of healthcare services. This research project uses an Adaptive Platform Design. This design allows the researchers to compare multiple infection prevention strategies within the same trial at the same time (rather than running separate trials), to analyse results as the trial occurs and to add new research questions during the course of the trial. The treatments that you may receive as part of the study will be determined by which domain(s) of the platform you participate in. By combining data collected within each domain as part of the platform, the researchers can investigate and compare treatment strategies and infection outcomes across a broader range of participants.

Inclusion Criteria: 1. Aged greater than or equal to 18 years of age 2. Diagnosis of haematological malignancy, including (CLL) chronic lymphocytic leukemia, (MM) multiple myeloma or (NHL) non-Hodgkin's lymphoma. 3. Eligible to receive or currently receiving Ig (IV or subcutaneous - SCIg) replacement for history of recurrent or severe infection(s) and IgG less than the lower limit of the reference range (excluding paraprotein) OR IgG\<4g/L (excluding paraprotein) 4. Life expectancy \> 12 months 5. Able to give informed consent Exclusion Criteria: 1\. Treating team deems enrolment in the study is not in the best interests of the patient.