Blood cancers

Liquid biopsy ctDNA testing is now ‘prime time’ for blood cancers

Circulating tumour DNA (ctDNA) testing is starting to make a difference in the management of haematological malignancies in Australia, according to local clinicians.

While still largely in the research setting, access to ctDNA genomic testing is being made available to some patients through the Christine and Bruce Wilson Centre for Lymphoma Genomics at the Peter MacCallum Cancer Centre in Melbourne.

Professor Miles Prince, director of blood cell therapies at Peter Mac and director of molecular oncology and cancer immunology at Epworth Healthcare, told the limbic it was now ‘prime time’ for ctDNA.

“Whereas we used to get a lot of false positives and negatives, the technology has really moved forward now and with even better sample collection and logistics behind it the DNA doesn’t get degraded and we can get analyses done fairly robustly.”

“It is exciting. The technology is there now to do some really good studies and build on the existing studies.”

He said studies have shown ctDNA in the context of large cell lymphoma can be helpful in detecting different and potentially targetable mutations.

“For example, EZH2 is a gene which is commonly expressed in both follicular lymphoma and large cell lymphoma and can be sometimes found in ctDNA and not found on node biopsy because you might get heterogeneity in the tumour.”

“It does seem to relate to tumour bulk so it is probably not going to be a great screening test for lymphoma but it is going to be helpful for us to look for potentially targetable mutations,” he said.

In one case of a T-Cell lymphoma where tumours were difficult to biopsy, ctDNA was able to identify PDL1 mutations that were responsive to pembrolizumab.

Professor Prince said unfortunately, right now, there were only a limited number of mutations that could be directly targeted.

“But with time that will grow so we have to be ahead ourselves. It is for the exception, rather than the routine at the moment.”

He said some of the current research around ctDNA included comparing it to PET imaging as a predictor of relapse and monitoring how quickly levels fall after treatment as a predictor of outcomes.

Professor Prince is also a co-founder of the Snowdome Foundation which supports research and diagnostic testing at the Wilson Centre.

He said clinicians can approach the Wilson Centre for access to ctDNA testing for patients with difficult tumours to biopsy.

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