A new study has identified genetic predictors of relapse in a common childhood leukaemia – the standard risk B-cell acute lymphoblastic leukaemia (SR B-ALL) – underscoring the importance of genetic testing for tailoring therapy for patients.
The identification of genomic predictors of relapse in SR B-ALL provides a basis for improved diagnosis, precise tailoring of treatment intensity and potentially the development of novel treatment approaches.
The study, carried out by scientists from St. Jude Children’s Research Hospital, Seattle Children’s and the Children’s Oncology Group (COG), has been published in the Journal of Clinical Oncology.
SR B-ALL relapse
Around 15 per cent of patients who achieve remission later experience a relapse, and previous studies examining genomic alterations to predict relapse risk have primarily focused on high-risk ALL subgroups.
SR B-ALL represents a larger group of patients and accounts for approximately half of children with ALL that relapse.
This study is one of the first to systematically examine genetic factors on a large scale that influence relapse risk in SR B-ALL.
“ALL, as the most common childhood cancer, is a great success story with over 90 per cent of children cured. But there remains a population of children whose disease is not fully cured, and we’ve not completely understood why that’s the case,” said co-senior author, Charles Mullighan, MBBS (Hons), MSc, MD, St. Jude Comprehensive Cancer Center Deputy Director and Department of Pathology member.
“This study focused on that group of poorly understood cases, where we know less about the features that influence the risk of treatment not working and the disease coming back.”
Identifying genes
Genomic profiling identifies specific genetic alterations associated with cancer susceptibility, relapse risk and how tumours respond to therapeutics.
These studies allow scientists and clinicians to predict how patients are likely to respond to therapy, providing insights that shape the treatment of childhood ALL.
Results from this collaborative study demonstrate the importance of genomic profiling in accurately determining patient risk in B-ALL, in conjunction with traditional criteria.
“We are planning to reduce conventional therapies in the future for children with ALL because we know that many patients can be cured with less therapy,” explained co-senior author, Mignon Loh, MD, leader of Seattle Children’s Cancer and Blood Disorders Center, COG ALL Committee chair emeritus, Seattle Children’s Ben Towne Center for Childhood Cancer Research director, and head of Seattle Children’s Division of Pediatric Hematology, Oncology, Bone Marrow Transplant and Cellular Therapy.
“We want to make sure we accurately identify those children, and because of the special design of the study, this project allowed us to do just that.”
The scientists conducted genome and transcriptome sequencing on both SR B-ALL samples that relapsed and samples that remained in complete remission in a one:two ratio.
They found that ALL subtypes, genetic alterations and patterns of aneuploidy (extra or missing chromosomes) were associated with the risk of relapse and time to relapse.
Some B-ALL subtypes, such as hyperdiploid and ETV6::RUNX1 ALL, had a low frequency of relapse, but others including PAX5-altered, TCF3/4::HLF, ETV6::RUNX1-like and BCR::ABL1-like were associated with an increased risk of relapse.
The specific type of genetic changes within those B-ALL subtypes further influenced the risk of relapse.
The results demonstrated that genetic variations and cancer subtypes influence relapse risk in SR B-ALL, and patients classified as standard-risk can have tumours with high-risk features.
“Whole genome sequencing was important to accurately and comprehensively identify these changes, and they could not all have been identified without it,” explained Mullighan.
“Children with SR ALL should have their tumour cell genome sequenced upon their initial diagnosis to identify if their tumour cells have these high-risk features, so that their initial therapy intensity can be increased.”
“Beyond conventional therapies, this information could also be used to develop and explore novel, personalised treatment strategies,” added Loh.
