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RecruitingLast updated: 23 October 2025

RATIONAL-PT (Dose-Ig domain): A study for people with blood cancers who are taking immunoglobulin to prevent infections, looking at whether a lower dose works just as well.Role of Antibiotic Therapy or Immunoglobulin On iNfections in hAematoLogy (Dose-Ig)

Trial purpose

Medical clipboardSide effect and wellbeing

Tumor type

Blood Cancers Haematological

Age

People18+

Trial acronym

RATIONAL-PT (Dose-Ig domain)

Clinical summary

Summary

This research project forms part of the RATIONAL Platform Trial. The study is being conducted to find out whether a lower dose of immunoglobulin (IVIg) is just as effective as preventing infections in people with blood cancers who have tried stopping in the past without success, or are not suitable to trial stopping immunoglobulin. The research will investigate if people can safely reduce their immunoglobulin dose after six months of therapy.

You may be eligible if you have a blood cancer and low levels of certain antibodies (immunoglobulins) in the blood. Your treating doctor will check to see if you are eligible to join, and you'll need to complete screening assessments to ensure it's safe for you to participate.

Study details

In this clinical trial domain, participants will be divided into two gropus (arms) to compare the different treatments. There is one usual care group and one investigational group. Each participant will be put into a group by chance (randomly). The two groups are:

  • Continue standard-dose immunoglobulin replacement therapy
  • Start low-dose immunoglobulin therapy

If eligible to participate in a domain of the RATIONAL-PT, your active study participation in that domain will last for 13 months and all participants will return to the hospital for a study visit every 3 months (4 more in-person visits after Day 1). During each month of the 12-month treatment period except the months in which you are attending in-person study visits, you will receive a phone call from your treating clinical team to check your progress (8 calls in total).

Even if you are recommended to, or choose to, stop your domain treatment during the 12-month treatment period, you will be asked to continue attending study visits and having phone calls until the end of the trial period (13 months in total) because researchers are still interested in your outcomes.

At the end of your participation on the study, your doctor will decide if you still require treatment to prevent infection, and if you do, whether to continue on the treatment you received during the study (standard-dose or low-dose immunoglobulin). 

The results of this trial will inform clinical decision making about the use of immunoglobulin and oral antibiotics for people with blood cancers. Your participation may help doctors who treat people with blood diseases in future to know what dose of immunoglobulin should be prescribed to try to prevent the onset of serious infections.

Conditions

This trial is treating people with blood cancers including chronic lymphocytic leukaemia (CLL), multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL) who are receiving IVIg replacement at a standard dose for infection prevention

Eligibility

Inclusion

Patients are eligible for the Dose-Ig domain of the RATIONAL-PT if they fulfil eligibility for both RATIONAL-PT and the Dose-Ig domain.

RATIONAL-PT inclusion criteria:
1. Aged greater than or equal to 18 years of age
2. Diagnosis of haematological malignancy, including Chronic Lymphocytic Leukaemia (CLL), Multiple Myeloma (MM) or Non-Hodgkin's Lymphoma (NHL)
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

Dose-Ig domain inclusion criteria:
1. Patients must be receiving IVIg replacement at standard dose for prevention of bacterial infections due to hypogammaglobulinaemia for at least 6 consecutive months.
2. Patient is not eligible for trial of Ig cessation in the opinion of the treating clinician and local investigator.

Exclusion

Patients are eligible for the Dose-Ig domain of the RATIONAL-PT if they fulfil eligibility for both RATIONAL-PT and the Dose-Ig domain.

RATIONAL-PT exclusion criteria:
1. Treating team deems enrolment in the study is not in the best interests of the patient

Dose-Ig domain exclusion criteria:
1. Prior or planned allogeneic haematopoietic stem cell transplantation.
2. Major infection (Grade 3 or higher) in preceding 3 months, and or current active infection requiring systemic antimicrobial treatment.
3. Previous splenectomy.
4. Known history of bronchiectasis.
5. Previous participation in this domain.
6. Treating team deems enrolment in the domain is not in the best interest of the patient.

Inclusion

  • You have had a certain type of treatment or surgical procedure.
  • You have the type of cancer, symptoms, or health risks that this clinical trial is focused on.

Exclusion

  • You have certain types of non-cancer medical conditions.
  • You have had certain treatments, surgical procedures or drugs.
Message

Clinical trials have complex eligibility criteria, and other criteria may apply for this trial. Ask your doctor about whether this trial could be right for you.

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Recruiting hospitals

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More information

Trial Identifiers

Information on this page is partially produced from ANZCTR, ClinicalTrials.gov *. View further details about this trial on the registry via the links below:

Trial sponsor

Monash University

Scientific Title

Role of Antibiotic Therapy or Immunoglobulin On iNfections in hAematoLogy (Dose-Ig)

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