Chronic Myeloid Leukaemia
The pre-treatment transcript level of t(9;22) [BCR-ABL] can inform prognosis and determine downstream log reduction levels.
In addition, three monthly follow up MRD analysis is recommended as per national and international guidelines.
Studies have indicated PB monitoring for most follow up time-points is sufficient, with BM monitoring at stipulated time points, according to national and ELN guidelines, where these will help to inform when cytogenetics testing is necessary.
The use of donor lymphocyte infusion (DLI) can be indicated in post-transplant patients. Therefore if DLI is being used, a clinically urgent test request can be made, so that a shorter turnaround time is implemented in the laboratory to support therapeutic decision making. This would also be available when other clinical urgencies require this, such as loss of a response or disease progression.
The availability of 2nd and 3rd plus generation drugs etc, their appropriate usage, and the occurrence of resistance to therapy due to the presence of ABL kinase domain mutations, requires additional testing.
We can send appropriate samples for an ABL kinase domain mutation screen to our collaborators, on behalf of referrers.
The current testing is applied to mutations occurring in the ABL kinase gene. This does not exclude other mechanisms of resistance that have been documented.
Acute Lymphocytic Leukaemia
In ALL, paired PB and BM samples are required for MRD monitoring in acute phase disease. Refer to the AML sample criteria for PB and BM samples required. We currently offer BCR-ABL testing for these patients.
Acute Myeloid Leukaemia
MRD monitoring is used to guide therapy and identify those patients at an increased risk of relapse. Paired PB and BM samples are required to accurately determine levels of MRD. This is because there can be large differences in the interpretation of the relapse risk if you are looking at leukaemic gene expression in PB or BM alone.
For this reason, it is important to identify the sample type (PB or BM) on the requisition form or request card.
The accurate monitoring of MRD requires samples to be fresh, to reach us ideally within 24 hours of phlebotomy and no later than 48 hours for reliable result generation. When it is not possible to obtain both samples, it is advised to send one sample PB or BM rather than miss the time point of MRD monitoring and the interpretation of the results will take this into account.
Core-Binding Factor (CBF) Leukaemias
Paired PB and BM samples are required for MRD as per the specimen requirements table.
Use of DLI or monitoring patients pre and post-transplant can be very informative for their clinical management. A repeat sample should always be tested if a significant change in transcript levels is observed to confirm this change, prior to any alteration in therapeutic decision making, which applies to all MRD monitoring.
Acute Promyelocytic Leukaemias
For APML, BM samples can indicate increased risk of relapse much earlier than PB. Residual transcript detection, following completion of treatment, is highly indicative of an increased risk of relapse. Paired PB and BM samples are the most informative specimens for MRD monitoring. As with all MRD, a pre-treatment diagnostic level is important to look at log reduction in levels over time.
In APL, there is also the advantage of being able to detect the genetic lesion in molecular assays if cytogenetic testing is unable to detect the translocation due to technical issues with the sample. This helps to confirm the diagnosis and inform clinical management of the patient.
Normal Karyotype AML testing
Note that FLT3 testing is currently performed by LabPMM. As many patients do not have a specific translocation to facilitate MRD monitoring, we routinely monitor for NPM1 and FLT3-ITDs on the diagnostic pre-treatment sample.
This is usually done on PB alone for FLT3-ITDs and both PB and BM for NPM1. In addition, the FLT3 D835 TKD variant is screened for.
Separate samples are required for FLT3-ITD and NPM1 screening because the tests are carried out on DNA and RNA respectively.
In 2005, the JAK2 V617F mutation was found in almost all patients with PV and about half of those patients with ET and IMF.
This test is now part of the clinical work up guidelines for diagnosing these patients.
For JAK2 molecular tests, 10ml EDTA PB is required and not a BM aspirate sample.
The JAK2 V617F mutation is found in ~95% of cases with PV, however approximately 5% of patients do not have this mutation.
It has been reported that the majority of the JAK2 V617F negative PV patients have a mutation in an alternative region of the JAK2 gene, within exon 12.
Currently we are able to send an appropriate aliquot of the archived DNA sample for screening exon 12 to our collaborators, on behalf of referrers.
Essential Thrombocythaemia and Idiopathic Myelofibrosis (IMF)
These patients are tested for JAK2 V617F mutation.
In JAK2 V617F-negative ET and IMF cases, 3-4% and 4-8% of patients respectively have a mutation in exon 10 of the MPL gene.
Mutations in exon 9 of the calreticulin gene (CALR) have been described in around one third of ET and IMF patients who are JAK2 V617F-negative and MPL-non mutated.
Screening of these mutations has been included as part of the BCSH criteria for the diagnosis of ET and IMF. CALR and MPL screening is performed by the laboratory.
B and T cell lymphomas
At the present time please discuss sample requirements with Leeds HMDS.
St James’s Institute of Oncology
Level 3 Bexley Wing
St James’s University Hospital
Leeds LS9 7TF
Telephone for General Enquiries: 01132067851
Clinical trials samples
We are the regional centre for haemato-oncology molecular testing.
The clinical trial protocol will advise on the appropriateness of referral to designated centres and when it is appropriate to use regional centres. When the MDC laboratory participates in a clinical trial as the designated UK centre for testing, this will be indicated in the trial protocol.
It is also appropriate to refer patients for molecular testing that are not participants in a clinical trial. Therefore these can be referred directly to the MDC laboratory and any advice required can be sought by contacting the laboratory.
Tests under development
(will be referred on by us until in-house testing is validated)
- JAK2 exon 12
- BCR-ABL mutation screen for the ABL kinase domain to provide information on drug resistance and to indicate changes that may be required in therapy based upon the mutation indicated
- Other new and established target genes as required for the molecular work up indicated by standard and best practice relating to leukaemia and lymphoma
- Next generation sequencing to assess increased panels of genes for diagnostic profiling to risk stratify patients for specific treatment options
- The above gene panel tests will be influenced by NHS E Test Directory requirements