What we’ve shown is that in all malignant germ cell tumours we’ve identified that two microRNA clusters, that’s miR-371-373 and miR-302 cluster that are specific clusters at two points within the genome are found at very high levels in the tumours themselves when we look at them and do genetic analysis. What the implications of that finding, that this is one of the first times that we have found a common or shared biological abnormality in these tumours which actually, in the way they present clinically and the way they appear under the microscope, are actually very diverse. Now, the way that helps us is potentially in diagnosis. What we’ve gone on to show is not only are these levels of microRNAs at very high levels in the tumours but also at the time of patient diagnosis with these tumours we’ve also found in the last year or two that the levels of these microRNAs are very high in patient bloodstream at diagnosis. We’ve also gone on to show in a number of patients that following treatment the levels of these microRNAs fall and reflect the clinical status of the patient.

Now, the numbers of patients we’ve looked at and published so far have been quite small but it will be important in the future to look at these microRNAs in the bloodstream and in other body fluids really in larger numbers to confirm these initial studies with a view to getting these tests into clinical practice.

So when we refer to marker positive cases we’re referring obviously to the proteins AFP and HCG that we use in clinical practice and what we know is that in marker positive cases, yes, at diagnosis these levels of miR-371-373 and miR-302 are high. But importantly there’s a significant proportion of patients who are also marker negative with malignant germ cell tumours and we find that these microRNAs are still positive. So whereas we previously believed perhaps 30% or 40% of patients overall with these tumours were marker negative, a combination of the traditional markers of AFP and HCG combined with these new microRNA tests correctly identify all patients with the disease.

Now, to date what we have shown is that we’ve studied malignant germ cell tumour cases which occur outside of the brain and we’ve looked at cases which occur in the gonads, the testes and the ovaries, and also extra-gonadal sites, so that’s other sites in the body. Up until now what hasn’t been done is to look at cerebrospinal fluid to look to see whether patients who have malignant germ cell tumours in the brain also have raised levels of these microRNAs.

MicroRNAs are expressed right from the earliest embryonic development. Which microRNAs and how much and the levels that are expressed change and are very carefully regulated during development and during life because, similar to protein coding genes, these non-protein coding genes, if the levels either become low or high, can act as cancer forming genes. So they are very carefully controlled and the understanding in cancers is that these microRNAs, in addition to other traditional protein coding genes, become altered or the levels become abnormal in some way. That can have consequences that the cell can then escape the normal mechanisms of control and can form a malignant growth. So, as I say, these microRNAs are important in development; what I would say about the microRNAs we have shown to be very high in malignant germ cell tumours is that in normal adult tissues that the levels of them are either not expressed at all or they’re expressed at very low levels. Therefore it makes things very easy for us when we’re measuring levels in the tissues or measuring levels in body fluids to identify between abnormally raised levels and the normal levels we see in normal healthy individuals.

The two clusters of microRNAs that we see in malignant germ cell tumours are miR-371-373, and that’s situated on chromosome 19, and also miR-302 cluster which is on chromosome 4. Now, although individual microRNAs from those clusters have been shown to be expressed at high levels in certain cancers, what hasn’t been shown in any other cancer is the fact that both of these clusters are expressed at very high levels and that’s a unique finding in malignant germ cell tumours. One of the advantages of that is that it helps to distinguish high levels of perhaps one or two of those microRNAs from those clusters from, as you mentioned, embryonal tumours where a small number of those microRNAs have been identified as being at high levels. That’s important because when you have a patient who presents to you with a mass and you’re not sure whether it’s a germ cell tumour or another embryonal type tumour, by profiling the full range of microRNAs that we see, the eight main microRNAs from those two clusters, we can be confident that what we’re looking at would be a malignant germ cell tumour from another type of tumour.

At present the work has been obviously laboratory based and what would be important over the next few years is to translate those early findings in patient samples into wider studies, confirming them in bigger cohorts of patients so that we can then establish this microRNA testing as a routine test in the hospital for patient benefit.

As a practising clinician one of the difficulties is trying to arrange complicated tests for patients which involve samples being on ice, delivered on dry ice. One of the advantages of these microRNAs, as you say, is they’re very stable, the samples can be left out at room temperature for days without affecting the results. So, for example, a sample that was left overnight in a hospital biochemistry lab, the result would be the same the following day as if being processed immediately. The practical use of that means that you’re far more likely to be able to get the result and have a reliable result and not have to repeat it and have more confidence in those findings. So there are numerous studies now that have shown that microRNAs are exceptionally stable at a variety of temperatures and they’ve also been shown to be useful in a forensic setting as well because of their stability over time and a number of months or even years sometimes.

We’re looking to do as part of this meeting is to increase collaboration between different groups who are looking at these microRNAs and also to look at adding amendments to clinical trials that are already open to specifically study these microRNAs as part of the wider trials that are ongoing.