Clonal hematopoiesis explored in aplastic anemia

Clonal hematopoiesis was detected in DNA samples from approximately half of 439 patients with aplastic anemia, and a third of the study population carried mutations in candidate genes that correlated with clinical outcomes, according to a report published online July 2 in the New England Journal of Medicine.

Most patients with aplastic anemia respond to immunosuppressive therapy or bone marrow transplantation, but about 15% later develop myelodysplastic syndromes, acute myeloid leukemia (AML), or both. Historically, this has been attributed to “clonal evolution,” but a more accurate term is clonal hematopoiesis. However, not all patients with clonal hematopoiesis go on to develop late myelodysplastic syndromes or AML, said Dr. Tetsuichi Yoshizato of the department of pathology and tumor biology at Kyoto (Japan) University and associates.

To clarify the role of clonal hematopoiesis in aplastic anemia, the investigators analyzed DNA in blood, bone marrow, and buccal samples from 439 patients with bone marrow failure who were treated at three specialized centers in the United States and Japan.

Targeted sequencing of a panel of genes that are recurrently mutated in myeloid cancers was performed; 249 mutations were detected in candidate genes for myelodysplastic syndromes/AML in 36% of the study population. And about one-third of patients whose DNA harbored mutations had multiple (as many as 7) mutations. The most frequently mutated genes were BCOR and BCORL1 (in 9.3% of patients), PIGA (7.5%), DNMT3A (8.4%), and ASXL1 (6.2%), which together accounted for 77% of all mutation-positive patients, the investigators reported.

In addition, 47% of patients had expanded hematopoietic cell clones. Clones carrying certain mutations were associated with a better response to immunosuppressive treatment, while clones carrying several other mutations were associated with a poor treatment response, lower survival, and progression to myelodysplastic syndromes/AML. Mutations in PIGA and BCOR and BCORL1 correlated with a better response to immunosuppressive therapy and better overall and progression-free survival; mutations in a subgroup of genes that included DNMT3A and ASXL1 were associated with worse outcomes.

The pattern of mutations in individual patients, however, varied markedly over time and was often unpredictable. “It should be underscored that the complex dynamics of clonal hematopoiesis are highly variable and not necessarily determinative,” Dr. Yoshizato and associates said (N. Engl. J. Med. 2015 July 2 [doi:10.1056/NEJMoa1414799]).

Although further genetic research is needed before these findings can be applied clinically to guide prognosis and treatment, they already “have implications for bone marrow failure, for early events in leukemogenesis, and for normal aging,” the investigators added.

Clonal hematopoiesis was detected in DNA samples from approximately half of 439 patients with aplastic anemia, and a third of the study population carried mutations in candidate genes that correlated with clinical outcomes, according to a report published online July 2 in the New England Journal of Medicine.

Most patients with aplastic anemia respond to immunosuppressive therapy or bone marrow transplantation, but about 15% later develop myelodysplastic syndromes, acute myeloid leukemia (AML), or both. Historically, this has been attributed to “clonal evolution,” but a more accurate term is clonal hematopoiesis. However, not all patients with clonal hematopoiesis go on to develop late myelodysplastic syndromes or AML, said Dr. Tetsuichi Yoshizato of the department of pathology and tumor biology at Kyoto (Japan) University and associates.

To clarify the role of clonal hematopoiesis in aplastic anemia, the investigators analyzed DNA in blood, bone marrow, and buccal samples from 439 patients with bone marrow failure who were treated at three specialized centers in the United States and Japan.

Targeted sequencing of a panel of genes that are recurrently mutated in myeloid cancers was performed; 249 mutations were detected in candidate genes for myelodysplastic syndromes/AML in 36% of the study population. And about one-third of patients whose DNA harbored mutations had multiple (as many as 7) mutations. The most frequently mutated genes were BCOR and BCORL1 (in 9.3% of patients), PIGA (7.5%), DNMT3A (8.4%), and ASXL1 (6.2%), which together accounted for 77% of all mutation-positive patients, the investigators reported.

In addition, 47% of patients had expanded hematopoietic cell clones. Clones carrying certain mutations were associated with a better response to immunosuppressive treatment, while clones carrying several other mutations were associated with a poor treatment response, lower survival, and progression to myelodysplastic syndromes/AML. Mutations in PIGA and BCOR and BCORL1 correlated with a better response to immunosuppressive therapy and better overall and progression-free survival; mutations in a subgroup of genes that included DNMT3A and ASXL1 were associated with worse outcomes.

The pattern of mutations in individual patients, however, varied markedly over time and was often unpredictable. “It should be underscored that the complex dynamics of clonal hematopoiesis are highly variable and not necessarily determinative,” Dr. Yoshizato and associates said (N. Engl. J. Med. 2015 July 2 [doi:10.1056/NEJMoa1414799]).

Although further genetic research is needed before these findings can be applied clinically to guide prognosis and treatment, they already “have implications for bone marrow failure, for early events in leukemogenesis, and for normal aging,” the investigators added.

Clonal hematopoiesis was detected in DNA samples from approximately half of 439 patients with aplastic anemia, and a third of the study population carried mutations in candidate genes that correlated with clinical outcomes, according to a report published online July 2 in the New England Journal of Medicine.

Most patients with aplastic anemia respond to immunosuppressive therapy or bone marrow transplantation, but about 15% later develop myelodysplastic syndromes, acute myeloid leukemia (AML), or both. Historically, this has been attributed to “clonal evolution,” but a more accurate term is clonal hematopoiesis. However, not all patients with clonal hematopoiesis go on to develop late myelodysplastic syndromes or AML, said Dr. Tetsuichi Yoshizato of the department of pathology and tumor biology at Kyoto (Japan) University and associates.

To clarify the role of clonal hematopoiesis in aplastic anemia, the investigators analyzed DNA in blood, bone marrow, and buccal samples from 439 patients with bone marrow failure who were treated at three specialized centers in the United States and Japan.

Targeted sequencing of a panel of genes that are recurrently mutated in myeloid cancers was performed; 249 mutations were detected in candidate genes for myelodysplastic syndromes/AML in 36% of the study population. And about one-third of patients whose DNA harbored mutations had multiple (as many as 7) mutations. The most frequently mutated genes were BCOR and BCORL1 (in 9.3% of patients), PIGA (7.5%), DNMT3A (8.4%), and ASXL1 (6.2%), which together accounted for 77% of all mutation-positive patients, the investigators reported.

In addition, 47% of patients had expanded hematopoietic cell clones. Clones carrying certain mutations were associated with a better response to immunosuppressive treatment, while clones carrying several other mutations were associated with a poor treatment response, lower survival, and progression to myelodysplastic syndromes/AML. Mutations in PIGA and BCOR and BCORL1 correlated with a better response to immunosuppressive therapy and better overall and progression-free survival; mutations in a subgroup of genes that included DNMT3A and ASXL1 were associated with worse outcomes.

The pattern of mutations in individual patients, however, varied markedly over time and was often unpredictable. “It should be underscored that the complex dynamics of clonal hematopoiesis are highly variable and not necessarily determinative,” Dr. Yoshizato and associates said (N. Engl. J. Med. 2015 July 2 [doi:10.1056/NEJMoa1414799]).

Although further genetic research is needed before these findings can be applied clinically to guide prognosis and treatment, they already “have implications for bone marrow failure, for early events in leukemogenesis, and for normal aging,” the investigators added.