I talked briefly about the objectives of the UKALL 2003 trial in an earlier post but will go a bit deeper into it here.
Initial allocation to a treatment regimen is based on the patient's age, initial white blood count and response to treatment at Days 8 and 15.
Minimum Residual Disease is a very fine genetic measurement tool to quantify remaining leukaemic cells in the bone marrow and is much more accurate than the traditional methods of counting leukaemic cells under a microscope.
The aim of this part of the trial is to see whether the intensity of treatment can be reduced for children with varying levels of MRD without effecting their chances of suffering a later relapse (or Event Free Survival – EFS - as it is known). The advantages of this is that many of the drugs used to treat leukaemia are highly toxic leading to a range of less and more serious side-effects. If fewer drugs can be administered, will this effect the outcome of the treatment?
At the end of the first block of treatment a measurement of Minimum Residual Disease (MRD) is taken. Children (whose WBC is satisfactory, fulfill age criteria, have had no complications etc) will be assigned randomly to Regimens A or B if their MRD count is considered low, or Regimens B or C if their MRD count is high.
There are really no advantages nor disadvantages to participating in the trial – its swings and roundabouts.
In Kezia's case her white blood counts were still too high to participate in this part of the trial – she was automatically assigned to Regimen C.
Another part of the trial is to evaluate a new form of the chemotherapy drug Asparaginase. Previously, it was necessary to have more frequent injections of Asparaginase. By pegalating the drug, it is released far more slowly into the bloodstream thus necessitating fewer injections. Pegalating a drug involves adding a molecule of polyethelene glycol to it. The study is basically looking at how pegalated asparaginase behaves – its release rates, how long it survives in the blood. It goes under the trade-name Oncaspar which you will also hear being used.
The final component of the trial is to assess Quality of Life aspects of leukaemia and leukaemia treatment for both the child and its parents. This is done through administering a short questionnaire at five time points during the treatment.