Outcomes With Palbociclib at Altered Dose and Schedule in Liposarcoma

Key Points

  • A palbociclib dose of 125 mg/d for 21 of 28 days appeared to be active in advanced well-differentiated or dedifferentiated liposarcoma.
  • The lower dose appeared to be associated with reduced toxic effects compared with the earlier-studied dose.

In a single-center phase II trial reported in JAMA Oncology, Dickson et al found that changing the dose and schedule of palbociclib (Ibrance) from those in a previous phase II trial appeared to maintain activity while potentially reducing hematologic adverse effects in patients with advanced well-differentiated or dedifferentiated liposarcoma. In the previous study, a palbociclib regimen of 200 mg/d for 14 days every 21 days in 30 patients was associated with median progression-free survival of 18 weeks and excessive hematologic adverse events.

New Dose and Schedule

In the current study, 60 patients were treated with palbociclib at 125 mg daily for 21 of every 28 days. Progression-free survival at 12 weeks was 57.2% (95% confidence interval [CI] = 42.4%–68.8%), and median progression-free survival was 17.9 weeks (95% CI = 11.9–24.0 weeks). One complete response lasting more than 2 years was observed.

Hematologic adverse events included grade 3 and 4 neutropenia in 33% and 3%, grade 3 anemia in 22%, and grade 3 and 4 thrombocytopenia in 5% and 2%. No neutropenic fever was observed. Dose was reduced to 100 mg/d in three patients and to 75 mg/d in one patient due to hematologic adverse events.

The investigators concluded: “In patients with advanced well-differentiated or dedifferentiated liposarcoma, treatment with palbociclib was associated with a favorable [progression-free survival] and occasional tumor response. This dose and schedule appears active and may have less toxic effects than 200 mg for 14 days.”

The study was supported by the National Cancer Institute, the National Institutes of Health, and Pfizer.

Mark A. Dickson, MD, of the Memorial Sloan Kettering Cancer Center in New York, is the corresponding author of the JAMA Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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