Photo by Chad McNeeley
HSCT preparation
Gene sequencing early after transplant may provide important prognostic information in patients with myelodysplastic syndromes (MDS), according to a new study.
Patients who had disease-associated mutations in the bone marrow 30 days after hematopoietic stem cell transplant (HSCT) were significantly more likely to experience disease progression and have lower rates of progression-free survival (PFS) at 1 year.
“Using our sequencing method, we’re identifying residual tumor cells before a pathologist could see them under the microscope and before a patient develops symptoms,” said Matthew J. Walter, MD, of Washington University in St. Louis, Mo.
“At that moment, there may be time to intervene in ways that could delay the cancer from coming back or potentially prevent it completely.”
Dr. Walter and his colleagues described results with their sequencing method in The New England Journal of Medicine.
The researchers sequenced bone marrow and skin (control) samples from 90 adults with MDS who underwent allogeneic HSCT.
The team used enhanced exome sequencing to detect mutations before HSCT and evaluated mutation clearance using error-corrected sequencing to genotype mutations in bone marrow samples collected 30 days after HSCT.
The researchers detected at least one validated somatic mutation in the pre-HSCT samples from 86 of 90 patients.
Of the 86 patients, 32 had at least one mutation with a maximum variant allele frequency of at least 0.5% detected 30 days after HSCT. The frequency is equivalent to 1 heterozygous mutant cell per 100 cells, the researchers explained.
Patients who experienced disease progression had mutations with a median maximum variant allele frequency of 0.9%, compared with 0% for patients who did not progress (P<0.001).
Progression occurred in 53.1% of patients who had one or more mutations with a variant allele frequency of at least 0.5% at 30 days, whereas progression occurred in 13% of patients who did not have such mutations. After adjusting for conditioning regimen, the hazard ratio (HR) for disease progression in the patients with mutations was 3.86 (P<0.001).
The 1-year PFS rate was 31.3% in patients who had one or more mutations with a variant allele frequency of at least 0.5% at 30 days and 59.3% in patients who did not have the mutations. After adjusting for conditioning, the HR for progression or death was 2.22 (P=0.005).
The researchers noted that PFS was lower in patients who had received reduced-intensity conditioning and had at least one persistent mutation with a variant allele frequency of at least 0.5% at day 30 (P≤0.001), when compared to other combinations of conditioning regimen and mutation status.
In multivariable analyses, the presence of a mutation with at least 0.5% variant allele frequency was associated with a more than four-fold risk of progression (HR, 4.48; P<0.001) and a more than two-fold risk of progression or death (HR, 2.39; P=0.002).
“Now that we have detected mutations early and shown that it predicts a higher risk of recurrence, we want to determine the best course of action for those high-risk patients,” Dr. Walter said.
He and his colleagues acknowledged that the high-coverage exome sequencing technique used for this study is not routinely available in the clinic. Therefore, the researchers also analyzed samples using a subset of genes that are usually included in gene sequencing panels for MDS and acute myeloid leukemia.
The researchers noted that this 40-gene panel revealed fewer patients (n=68; 79%) with mutations, but “the prognostic value of detection of measurable residual disease was still highly clinically significant.”
With this approach, the presence of at least one mutation with a variant allele frequency of at least 0.5% 30 days after HSCT was associated with a higher risk of disease progression at 1 year (HR, 3.39; P=0.001) and a higher risk of progression or death at 1 year (HR, 2.09; P=0.02).
This study was supported by grants from the Leukemia and Lymphoma Society and other groups.