Novel drug may benefit myelofibrosis patients

Volume 4, Issue 4, 2015


Research shows that imetelstat can induce remission for some.

Ayalew Tefferi, M.D.

Ayalew Tefferi, M.D.

Researchers in the Mayo Clinic Cancer Center are studying a novel drug called imetelstat for the treatment of patients with myelofibrosis.

Myelofibrosis is a chronic myeloid cancer in which bone marrow cells that produce blood cells develop and function abnormally. Imetelstat works by inhibiting telomerase activity in tumor cells, which leads to cell death.

Results of a Mayo Clinic study of the drug were published in the New England Journal of Medicine in September 2015.

"We observed that imetelstat was active and induced morphologic and molecular remissions in some patients with myelofibrosis," said Ayalew Tefferi, M.D., a hematologist in the Mayo Clinic Cancer Center and lead author of the published study. "We also observed that imetelstat demonstrated selective anticlonal activity, inhibiting the growth of cancer cells, which we had not previously documented with other drugs."

Myelofibrosis is characterized by bone marrow scarring, and although patients may derive symptomatic relief from other treatments, such as ruxolitinib, they usually don't revert back to normal bone marrow, Dr. Tefferi said. But with imetelstat treatment, some patients have reverted back to normal bone marrow, he said.

Researchers studied 33 patients, with a median age of 67, who were treated with imetelstat. Nearly half the patients in the group had received prior treatment with a JAK inhibitor.

Researchers noted a complete or partial remission in seven patients treated with imetelstat. The median duration of complete response was 18 months. Bone marrow fibrosis was reversed in all four patients who experienced a complete response, and a molecular response was documented in three of the four patients.

"We noted a difference in response rates, especially in complete remission rates, in patients with and without certain specific gene mutations, such as ASXL1, SF3B1 and U2AF1," Dr. Tefferi said. "This underscores the need for laboratory correlative studies in future clinical trials."

Treatment-related side effects included thrombocytopenia, neutropenia, anemia and elevation in liver function enzyme levels. Geron Corp. provided funding for the study.