receiving chemotherapy
Photo by Rhoda Baer
Patients with TP53-mutated myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) may benefit from treatment with decitabine, according to a study published in NEJM.
All patients in this study who had TP53 mutations responded to decitabine.
Although these responses were not durable, the patients’ median overall survival was similar to that of patients with lower-risk disease who received decitabine.
“The findings need to be validated in a larger trial, but they do suggest that TP53 mutations can reliably predict responses to decitabine, potentially prolonging survival in this ultra-high-risk group of patients and providing a bridge to transplantation in some patients who might not otherwise be candidates,” said study author Timothy J. Ley, MD, of Washington University School of Medicine in St. Louis, Missouri.
For this study, Dr Ley and his colleagues analyzed 116 patients—54 with AML, 36 with relapsed AML, and 26 with MDS.
Eighty-four of the patients were enrolled in a prospective trial and received decitabine at a dose of 20 mg/m2/day for 10 consecutive days in monthly cycles. Thirty-two additional patients received decitabine on different protocols.
To determine whether genetic mutations could be used to predict responses to decitabine, the researchers performed enhanced exome or gene-panel sequencing in 67 of the patients. The team also performed sequencing at multiple time points to evaluate patterns of mutation clearance in 54 patients.
Response
Thirteen percent of patients (n=15) achieved a complete response (CR), 21% (n=24) had a CR with incomplete count recovery, 5% (n=6) had a morphologic CR with hematologic improvement, and 7% (n=8) had a morphologic CR without hematologic improvement.
Eight percent of patients (n=9) had a partial response, 20% (n=23) had stable disease, and 16% (n=19) had progressive disease.
There were 21 patients with TP53 mutations, and all of them achieved bone marrow blast clearance with less than 5% blasts.
Nineteen percent (n=4) had a CR, 43% (n=9) had a CR with incomplete count recovery, 24% (n=5) had morphologic CR with hematologic improvement, and 14% (n=3) had morphologic CR without hematologic improvement.
“What’s really unique here is that all the patients in the study with TP53 mutations had a response to decitabine and achieved an initial remission,” Dr Ley said.
“With standard aggressive chemotherapy, we only see about 20% to 30% of these patients achieving remission, which is the critical first step to have a chance to cure patients with additional therapies.”
Dr Ley and his colleagues also found that patients in this study were likely to respond to decitabine if they were considered “unfavorable risk” based on extensive chromosomal rearrangements. (Many of these patients also had TP53 mutations.)
Indeed, 67% (29/43) of patients with an unfavorable risk had less than 5% blasts after treatment with decitabine, compared with 34% (24/71) of patients with intermediate or favorable risk.
“The challenge with using decitabine has been knowing which patients are most likely to respond,” said study author Amanda Cashen, MD, of Washington University School of Medicine.
“The value of this study is the comprehensive mutational analysis that helps us figure out which patients are likely to benefit. This information opens the door to using decitabine in a more targeted fashion to treat not just older patients, but also younger patients who carry TP53 mutations.”
Survival and next steps
The researchers found that responses to decitabine were usually short-lived. The drug did not provide complete mutation clearance, which led to relapse.
“Remissions with decitabine typically don’t last long, and no one was cured with this drug,” Dr Ley noted. “But patients who responded to decitabine live longer than what you would expect with aggressive chemotherapy, and that can mean something. Some people live a year or 2 and with a good quality of life because the chemotherapy is not too toxic.”
The median overall survival was 11.6 months among patients with unfavorable risk and 10 months among patients with favorable or intermediate risk (P=0.29).
The median overall survival was 12.7 months among patients with TP53 mutations and 15.4 months among patients with wild-type TP53 (P=0.79).
“It’s important to note that patients with an extremely poor prognosis in this relatively small study had the same survival outcomes as patients facing a better prognosis, which is encouraging,” said study author John Welch, MD, PhD, of Washington University School of Medicine.
“We don’t yet understand why patients with TP53 mutations consistently respond to decitabine, and more work is needed to understand that phenomenon. We’re now planning a larger trial to evaluate decitabine in AML patients of all ages who carry TP53 mutations. It’s exciting to think we may have a therapy that has the potential to improve response rates in this group of high-risk patients.”
