International consensus criteria for the assessment of response and minimal residual disease in multiple myeloma may be ahead of clinical practice in Australia.

Dr Louise Wienholt, from the Royal College of Pathologists of Australasia’s (RCPA) Quality Assurance Program, told the limbic that there was too much variability between laboratories in Australia with respect to tests for monitoring multiple myeloma.

She said the 2016 consensus document by the International Myeloma Working Group recognised the need to better define the improved patient response to the many new drug treatments for myeloma.

“Newer tests such as next-generation sequencing and multiparamtetric flow cytometry look at millions of cells and can detect minimal residual disease which is strongly linked to clinical remission or relapse.”

“However most of these assays lack standardisation between centres and external quality assurance,” she said.

Speaking at the RCPA’s Pathology Update at the International Convention Centre Sydney last week, Dr Wienholt said there were still also significant variations between conventional markers of tumour load such as urine and serum protein electrophoresis (SPEP).

Some of the factors influencing variability were methodological such as sample collection while others were the difficulty in interpretation, even for experienced scientists.

“Clinicians are not necessarily aware that no one indicator can be used to accurately define clinical remission,” she said.

“For example, serum protein electrophoresis is more accurate with very high levels of monoclonal protein. If the levels are low, the variability is too wide to know if it truly represents clinical remission.”

She said clinicians should also be aware of variability in results between laboratories – particularly as myeloma was becoming more like chronic disease.

“Results from different laboratories are not interchangeable. We need more standardisation in our assays and a robust evaluation of newer tests,” she said.

She also said the international consensus criteria were particularly useful for establishing baselines and monitoring patients in the context of clinical trials for new drugs.

However the criteria were not yet as applicable in clinical practice.