FEATURE
quencing amplifies all possible sequences in the
gene region of interest. At diagnosis, patients
get a signature for that particular leukemia that
can be screened for in subsequent tests.
“In standard PCR testing, we have to
do a special test for each patient. In nextgeneration sequencing we only do one test for
all possible sequences and then look for that
particular signature,” Michael J. Borowitz,
MD, PhD, professor of pathology and oncology at Johns Hopkins Medical Institutions in
Baltimore, Maryland, explained.
Next-generation sequencing has a greater
sensitivity and, according to Dr. Hunger, is
able to “get down to one cell of a 100,000 and,
potentially, to one cell in a million.”
This emerging technology is predicted
to become the future of MRD detection for
ALL, but there are still hurdles to overcome –
including a need for large-scale clinical trials
– before it is used widely in practice.
Powerful Prognostics
MRD monitoring aids in risk stratification,
can be used to determine the efficacy of treatment, identify the presence of tumor cells
after therapy, or determine the best timing for
a stem cell transplantation. MRD may also
forecast the possibility of a relapse – although
those in the field caution that MRD does not
define relapse.
Ample research has shown that MRD is a
valuable risk-prediction tool in pediatric patients with ALL. In a recent study, Dr. Pui and
colleagues found that patients who had MRD
on day 19 of remission induction therapy had
significantly worse 10-year event-free survival
(EFS) rates than those who tested negative
– regardless of their initial risk stratification.1 Patients who were categorized as being
low-risk but who had MRD levels ≥1 percent
had 10-year EFS rates of just 69.2 percent,
while patients who were initially categorized
as standard-risk but who had MRD levels <1
percent had 10-year EFS rates of 82.9 percent.
Due to its highly prognostic nature, hematologists and oncologists often use MRD
monitoring to tailor therapies for pediatric
patients based on their risk level.
For instance, Dr. Borowitz explained,
patients who test positive for MRD or those
who have the highest levels of ɕͥ