Adding Ibrance Stops Growth of Metastatic Triple-Positive Disease for More Than a Year

Ibrance (chemical name: palbociclib) plus the standard-of-care first treatments for metastatic hormone receptor-positive, HER2-positive breast cancer dramatically increased progression-free survival. This was according to results of the PATINA trial presented at the 2024 San Antonio Breast Cancer Symposium.

Progression-free survival is how long a person lives without the cancer growing.

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  Progression-free survival was 44.3 months with Ibrance and the standard of care, compared to 29.1 months for the standard of care alone.

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  This benefit was seen in all subgroups of the study, including people who had previously received anti-HER2 medicines for early-stage disease.

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  While people who received Ibrance had more side effects, these were expected and rates of severe (grade 4 or higher) side effects were equal in both treatment groups.

While Ibrance isn’t yet approved to be used in this way, Dr. Otto Metzger of the Dana-Farber Cancer Institute, who presented the results, said Pfizer, the company that makes Ibrance, is expected to file an application for U.S. Food and Drug Administration approval, as well as for approvals outside the United States. There is no way to predict how long this approval will take. It could be a few months to a few years.

“Palbociclib [Ibrance] added to anti-HER2 and endocrine therapy may represent a new standard of care for patients diagnosed with hormone receptor-positive, HER2-positive advanced-stage breast cancer,” Metzger said. “We feel this data is compelling and, hopefully, should be a regimen that is widely available for patients diagnosed with this type of breast cancer.

“We’re talking about patients being on a treatment that’s well tolerated, where patients continued to work, continued to carry on with their lives, despite being on treatment for metastatic breast cancer, for four years, which is remarkable.”

The PATINA study included 518 people (three were men) diagnosed with metastatic hormone receptor-positive, HER2-positive breast cancer. About 91% were white. Half were older than 53 and half were younger.

All the people started off by receiving what the researchers called induction therapy. This consisted of six to eight cycles of one or two anti-HER2 medicines: Herceptin (chemical name: trastuzumab), with or without Perjeta (chemical name: pertuzumab), along with vinorelbine or taxane chemotherapy. Taxane chemotherapy medicines include Taxol (chemical name: paclitaxel) and Taxotere (chemical name: docetaxel).

After the people completed the induction therapy, they stayed in the study only if the cancer had not grown.

In the second part of the study, the people were randomly assigned to one of two treatments:

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  257 people received Herceptin, with or without Perjeta, plus either an aromatase inhibitor or Faslodex (chemical name: fulvestrant)

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  261 people received the same regimen, plus Ibrance

Overall, 97% of the people received both Herceptin and Perjeta and 91% received an aromatase inhibitor.

After five years of follow-up, progression-free survival was 44.3 months among people who received Ibrance plus the standard of care and 29.1 months among people who received only anti-HER2 therapy and hormonal therapy. This represents a 26% decrease in the risk of the cancer growing.

Progression-free survival was better in all the subgroups the researchers analyzed, including people who received anti-HER2 medicines for early-stage disease and people who did not, as well as people who received only Herceptin.

Data on overall survival — how long the people lived whether or not the cancer grew — is still being collected, but there was a trend for better overall survival among people who received Ibrance.

The most common side effects among people who received Ibrance were:

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  grade 3 neutropenia (low white blood cell counts): 63%

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  grade 2 fatigue: 23%

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  grade 2 diarrhea: 26% 

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  grade 2 mouth sores: 17%

Metzger, O. et al.  AFT-38 PATINA: A Randomized, Open Label, Phase III Trial to Evaluate the Efficacy and Safety of Palbociclib + Anti-HER2 Therapy + Endocrine Therapy vs. Anti-HER2 Therapy + Endocrine Therapy after Induction Treatment for Hormone Receptor-Positive (HR+)/HER2-Positive Metastatic Breast Cancer. 2024 San Antonio Breast Cancer Symposium. Abstract GS2-12.