Blood Test Predicts Lymphoma Therapy Success

Diffuse large B cell lymphoma, a blood cancer, is the most common type of non-Hodgkin lymphoma and because it is highly biologically variable, patients vary widely in their response to treatment. Although most people are cured by conventional therapy, about one-third are not. Being able to predict early in the course of treatment those who will need additional or more aggressive therapies would be a significant boon to both clinicians and patients.

A large team of scientists led by Stanford Medicine (Stanford, CA, USA) tracked circulating tumor DNA (ctDNA) levels in 217 people with diffuse large B cell lymphoma that were treated at six medical centers, three in the USA and three in Europe. For each patient, they compared levels of ctDNA before treatment began with the levels after the first and second rounds of conventional chemotherapy. They then correlated those changes with each patient's outcome.

The scientists found that ctDNA was detectable prior to the initiation of therapy in 98% of the people studied, and, as would be expected, the amount of ctDNA in the blood dropped in all patients once treatment began. However the precipitousness of the decline varied. Those people whose ctDNA levels dropped a hundredfold after the first round or three-hundredfold by the second round were much more likely to live 24 months or more without experiencing a recurrence of their disease than those whose ctDNA levels declined more slowly.

David M. Kurtz, MD, PhD, the lead author of the study, said, “We found that ctDNA levels serve as a very sensitive and specific biomarker of response to therapy within as few as 21 days. Every year, about 30,000 people in the USA are diagnosed with diffuse large B cell lymphoma and, for the most part, they're treated with six cycles of combination therapy. But we know that not all patients need six cycles. A large fraction could be cured with fewer cycles, maybe even just two. If we can identify those people who are responding extremely well, we could spare them additional treatments. Conversely, we could intensify the therapy or seek other options for those who are not responding as well as we would have hoped.” The study was published on August 20, 2018, in the Journal of Clinical Oncology.

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