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RecruitingLast updated: 23 October 2025

RATIONAL-PT (Stop-IG domain): A study for people with blood cancer who are taking immunoglobulin to prevent infection to test whether further treatment with antibiotics or immunoglobulin is more effectiveRole of Antibiotic Therapy or Immunoglobulin On iNfections in hAematoLogy (Stop-Ig)

Trial purpose

Medical clipboardSide effect and wellbeing

Tumor type

Blood Cancers Haematological

Age

People18+

Trial acronym

RATIONAL-PT (Stop-IG domain)

Clinical summary

Summary

This research forms part of the RATIONAL Platform Trial. This study aims to find out whether people with blood cancers who are receiving immunoglobulin therapy (IVIg or SCIg) to prevent infections can safely stop after six months and instead take oral antibiotics to prevent serious infections. It will also test whether oral antibiotics should be taken daily or only when symptoms of an infection appear.

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 if you are eligible to participate, 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 three groups (arms) to compare the different treatments. There is one usual care group and two investigational groups. Each participant is put into a group by chance (randomly). The three groups are:

  • Continue immunoglobulin - this is the usual care group
  • Stop immunoglobulin and take daily oral antibiotics
  • Stop immunoglobulin and keep oral antibiotics at home to take only when infection symptoms start

If eligible to participate in a domain of RATIONAL-PT, your active 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 in 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 (immunoglobulins, antibiotics or none).

The results of this trial will inform clinical decision making about the use of immunoglobulin and oral antibiotics for people wtih blood cancers. Your participation may help doctors who treat patients with blood diseases in the future to know whether to prescribe oral antibiotics or immunoglobulins 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 currently receivnig immunoglobulin

Eligibility

Inclusion

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

Stop-Ig domain inclusion criteria:
1. Patients must be receiving Ig (IV or subcutaneous - SCIg) replacement for prevention of bacterial infections due to hypogammaglobulinaemia for at least 6 consecutive months.
2. Patient is eligible for trial of Ig cessation in the opinion of the treating clinician and local investigator.
3. Willing and able to comply with each of the treatment arms.

Exclusion

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

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

Stop-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. Already receiving systemic antibiotic prophylaxis for the purpose of preventing bacterial infection (NB: patients may receive antiviral, antifungal and Pneumocystis jirovecii Pneumonia (PJP) prophylaxis).
4. Intolerance of all trial antibiotic options in either arm A or arm B.
5. Communication, compliance or logistical issues (e.g. living long distance from medical facility) that are likely to limit a patient’s ability to take prophylactic or emergency antibiotics, or to obtain urgent medical attention for symptoms of infection.
6. Pregnant or breastfeeding.
7. Severe renal impairment (estimated or measured creatinine clearance of <30mL/min).
8. Previous splenectomy.
9. Previous participation in this domain

10. Treating team deems enrolment in the domain is not in the best interests 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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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 (Stop-Ig)

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