Blood cancers

Genome-wide microarray for MM and CLL coming to a lab near you

MBS funding for genome-wide microarray testing (GWMA) has been recommended by MSAC for people with multiple myeloma (MM) and chronic lymphocytic leukaemia (CLL).

The positive outcome recognises the advantages of GWMA for patients with haematological cancers including returning results faster and detecting more genetic variations than karyotyping.

“For MM, MSAC supported the creation of a new MBS item for GWMA limited to one use per patient lifetime, acknowledging the complementary nature of this test with fluorescence in situ hybridisation (FISH), which MSAC had supported in August 2019.”

“For CLL, MSAC supported the modification of MBS item 73343 to allow either FISH or GWMA as alternatives, limited to testing no more frequently than one test per year…,” the Public Summary Document said.

Dr Helen Wordsworth, Chair of the Haematology Advisory Committee of the Royal College of Pathologists of Australasia (RCPA), told the limbic the improved quality of information from GWMA would help drive better decision-making.

However the MSAC decision also had to be supported by some PBAC changes.

“At the moment there are a number of drugs – ibrutinib, idelalisib and venetoclax – that are available for treating patients with relapsed/refractory CLL in the setting where they have a demonstrated particular abnormality in one of the genes.

“At the moment the PBS restriction specifically says the genetic abnormality has to be demonstrated using FISH. Obviously if people switch over from using FISH to microarray, then PBAC will need to broaden that restriction to make it technology agnostic.”

While there was currently no similarly direct impact on treatment for multiple myeloma, Dr Wordsworth says there was the potential for that in the future.

“So doctors and patients can have a really informed discussion at the outset about the prognosis for the disease; the level of risk of the disease and in an ideal world, you would then actually choose your treatment to match that risk. In the future there is the potential for targeted therapies that might come online.”

She said she expected there would be speedy uptake of GWMA.

“There are some jurisdictions where arrays are already being used but not funded under the MBS and then there’ll be other places where the technology is not yet up and going.

“In my own lab, we have certainly worked up the technologies and will be ready to go with them. I think other labs will take the opportunity to get going with this sort of testing once the funding is available.”

“Arrays and then ultimately genetic sequences will need to be considered in terms of investigating these diseases, in the future not just in CLL and multiple myeloma, but in many other diseases as well.”

Dr Wordsworth, from Sullivan Nicolaides Pathology in Brisbane, said traditional karyotyping was not particularly informative in these diseases because of the nature of the cancer itself.

“It might detect 20-30% of patients with an abnormality; in fact if you use more sensitive types of techniques like these microarrays, then most patients will have some sort of genetic abnormality.”

She noted also that as haematological cancers evolved, the percentage of cases with genetic abnormalities also increased.

So there was an argument that the restriction on GWMA of once per patient lifetime in multiple myeloma was too strict.

Dr Wordsworth said more frequent testing would be preferable however the RCPA had no immediate plans to pursue that.

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