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RecruitingLast updated: 13 October 2025

CLOCK: This study is testing different fluids used to keep central lines (CVADs) clear in children receiving cancer treatment, to see which causes the fewest problemsPreventing adverse events during paediatric cancer treatment: A multi-site hybrid randomised controlled trial of catheter lock solutions (The CLOCK trial)

Trial purpose

Medical clipboardSide effect and wellbeing

Tumor type

Multi-Cancer Multi-Cancer

Age

People0 - 18

Trial acronym

CLOCK

Clinical summary

Summary

Across Australia every year, children undergoing treatment for cancer experience more than 250 blood stream infections, 70 deeo vein thromboses, and 300 blockages - all caused from the central line. This central venous access device (CVAD) is vital as it administers treatments such as chemotherapy drugs and supportive therapies including blood transfusions and antibiotics, however we need to do more to prevent harm.

When teh CVAD is not in use, it is locked with fluid. This fluid lock is an opportunity to prevent CVAD-associated complications. Therefore, the aim of this study is to compare the safety and effectiveness of three different locking solutions: KiteLock, heparinised saline and normal saline.

Participants will be randomly allocated to receive either the normal saline, heparinised saline, or KiteLock administered into the lumen of the CVAD.

The solution will be administered at a frequency based on clinical requirement plus during routine management procedures, with a maximum of one dose per 24 hours. This will continue until the device is removed or the participant withdraws from the study, for up to a maximum of 3 months post-enrolment. 

Throughout this study period, participants may be assessed by their treating clinicians for bloodstream infections using blood cultures, for CVAD-associated thrombosis (i.e. blood clots) with ultrasound or venography, for blockages of the CVAD with a test of injection and/or aspiration catheter occlusion, and for CVAD failure requiring removal. Participants will also be monitored for any adverse events, with a research nurse contacting them twice weekly across the study period. A questionnaire assessing health-related quality of life will be given to participants at the trial commencement and completion. Participants will additionally be followed up at 1 and 5 years after study completion (using medical records only).

It is hoped that this study may help to identify the locking solution with the least complications and adverse effects, in order to prevent harm in children with a CVAD undergoing treatment for cancer.

Conditions

This trial is treating people with a solid cancer or malignant blood condition and have a CVAD in place

Eligibility

Inclusion

Children (<18 years) with an oncological or malignant haematological condition who have a CVAD in situ (including peripherally inserted central catheters [PICCs], tunnelled (cuffed or non-cuffed) [e.g. Hickman®; Becton Dickinson, US] and totally implanted [e.g. PORT-A-CATH®; Smith Medical, US] will be eligible for inclusion.

Exclusion

 

- End-of-life pathway/measures at recruitment
- Pre-existing coagulopathic condition not related to current diagnosis or treatment (e.g. Haemophilia A and B or other factor deficiency; Immune Thrombocytopenic Purpura (ITP); Von Willebrand’s disease)
- Known allergy to heparin or T-EDTA

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.
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 *. View further details about this trial on the registry via the links below:

Trial sponsor

University of Queensland

Scientific Title

Preventing adverse events during paediatric cancer treatment: A multi-site hybrid randomised controlled trial of catheter lock solutions (The CLOCK trial)

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