Ibrance Shows Promise in Treatment of Myelofibrosis

An Ibrance-Jakafi combination shows promise in a mouse model of myelofibrosis.

A drug used to treat advanced breast cancer may offer a new treatment option for myelofibrosis, a rare blood cancer, according to a new study. The research was done in a mouse model, so the finding is preliminary and useful for guiding research, not treatment decisions.

The medication, Ibrance (palbociclib) may be able to prevent the scarring of bone marrow that existing treatments for myelofibrosis cannot, according to the study published in Cancer Research. The scarring disrupts the marrow’s production of blood cells and causes severe anemia that leaves patients weak and fatigued, and often makes blood clotting difficult, leading to an enlarged spleen, University of Virginia Health said in a news release.

Myelofibrosis occurs in approximately 1 to 1.5 of every 100,000 people, primarily those who are middle-aged or older. Patients with intermediate or high-risk cases typically survive only 16 to 35 months.

While Jakafi (ruxolitinib) is used to relieve patients’ symptoms, it does not offer significant reduction in bone marrow fibrosis and often loses its effectiveness with prolonged use, the researchers wrote. The new research suggests that pairing the drug with Ibrance may make for a superior treatment, UVA said.

“Current therapies only provide symptomatic relief without offering significant improvement of bone marrow fibrosis. So, there is a critical need to develop more effective therapy for myelofibrosis,” said Golam Mohi, Ph.D., the senior author of the study in the Cancer Research and a researcher in the Department of Biochemistry and Molecular Genetics in UVA’s School of Medicine.

To that end, Mohi and other researchers identified CDK6, a regulator of cell cycle, as a new therapeutic target in myelofibrosis. “We demonstrate that CDK4/6 inhibitor palbociclib (Ibrance) in combination with ruxolitinib (Jakafi) markedly inhibits myelofibrosis, suggesting this drug combination could be an effective therapeutic strategy against this devastating blood disorder,” he said in the press release.

Ibrance, dampens the activity of bone marrow in patients with metastatic breast cancer, reduced bone marrow scarring in two different mouse models of myelofibrosis. It also decreased the abnormally high levels of white blood cells seen in myelofibrosis and shrank the mice’s enlarged spleens.

Combining the drug with Jakafi produced a number of positive outcomes, the researchers said. The combination restored the bone marrow and white blood cell counts to normal and dramatically reducing the size of the mice’s enlarged spleens.

The study results suggest support the clinical investigation of the palbociclib and ruxolitinib combination in patients with myelofibrosis, Mohi told Managed Healthcare Executive®. “We are working with hematologists and oncologists at UVA Cancer Center to submit a proposal for clinical trial of this drug combination in myelofibrosis patients,” he said.