Palbociclib halts tumor growth in early breast cancer patients

Recently published in the Journal of Clinical Oncology ,researchers from the Institute of Cancer Research (London, UK) and The Royal Marsden NHS Foundation Trust (London) have demonstrated that palbociclib alongside an aromatase inhibitor shrank tumors in half of women with early-stage breast cancer and stopped tumor growth entirely in 90% of women.

Palbociclib was compared to the hormone treatment alone which showed similar tumor shrinkage but only halted tumor growth in 59% of early breast cancer patients. The results were recently published in the Journal of Clinical Oncology.

The trial was designed to test the benefit of adding palbociclib to hormone treatment before the patients undergo surgery. Longer-term clinical trials are ongoing, to assess whether the administration of the drug combination after surgery could delay breast cancer recurrence.

The study involved 307 postmenopausal women with hormone receptor-positive breast cancer that had not begun to metastasize, and who had not yet had surgery to remove their tumor. Tumor samples were taken before, during and after a 14-week course of treatment.

The investigation also revealed that adding palbociclib slowed both growth and death of cancer cells, explaining why the tumors didn’t shrink as much as they had anticipated.

Stephen Johnston (The Royal Marsden) commented: “Patients with breast cancer often respond to various drug treatments, only for the cancer cells to adapt, change or sidestep the initial beneficial effects.

“We have demonstrated that the current standard of care for many women – hormone treatment – is effective at stopping the growth of tumor cells prior to surgery, however with the addition of this new drug palbociclib patients may benefit even further,” Johnston added.

He continued: “We are hopeful, based on the results of this large trial, that combining this targeted therapy with hormone treatment may help to delay or even stop cancer coming back. This will require further research to confirm, however these results are a vital step forward tackling one of the major challenges that we encounter with breast cancer.”