End-of-study data from the CLEOPATRA trial supports the long-term efficacy of Genentech‘s Perjeta (pertuzumab) plus Herceptin (trastuzumab) and docetaxel chemotherapy for patients with previously untreated HER2-positive metastatic breast cancer.
Patients on the Perjeta combination regimen lived a median 16.3 months longer, compared with the control group not receiving Perjeta, an improvement considered “unprecedented” for this type of cancer.
The results were presented at the American Society of Clinical Oncology (ASCO) 2019 Annual Meeting by Sandra M. Swain, MD, FASCO, a breast cancer specialist and professor at Georgetown University.
Trial data were highlighted in the poster, “End-of-study analysis from the phase III, randomized, double-blind, placebo (Pla)-controlled CLEOPATRA study of first-line (1L) pertuzumab (P), trastuzumab (H), and docetaxel (D) in patients (pts) with HER2-positive metastatic breast cancer (MBC).”
“Our science-driven approach has been transforming standards of care in breast cancer for more than 20 years, and we are excited to present data from a Perjeta study that showed an unprecedented survival benefit for patients living with advanced HER2-positive disease,” Sandra Horning, MD, Roche’s chief medical officer and head of global product development, said in a press release.
The CLEOPATRA study (NCT00567190) was a Phase 3 study evaluating first-line treatment with intravenous infusions of Perjeta or placebo, added to Herceptin and docetaxel, in 808 patients with HER2-positive breast cancer whose cancer had come back (recurrent) and spread elsewhere in the body (metastatic).
After a long-term follow-up of eight years, patients in the Perjeta group had an overall survival of 57.1 months, compared with 40.8 months in the control arm (placebo, Herceptin and chemotherapy). This means they lived 16.3 months longer, with a 31% overall reduction in the risk of death.
At the 8-year landmark, over a third (37%) of the patients on the Perjeta regimen were alive versus less than one quarter (23%) in the control group.
These new data are consistent with the previously reported results of 50 months follow-up and confirm the unparalleled overall survival benefit of the Perjeta-based regimen after an additional four years of follow-up, Roche (which owns Genentech) said in the release.
The long-term triple combo’s safety was generally consistent with that known for Perjeta and maintained the safety profiles reported at 50 months. Since this prior analysis, there were only two new heart-related events — a serious adverse event suggestive of heart failure and another one of left ventricular systolic dysfunction, which were both resolved.
Likewise, data from the Chinese PUFFIN Phase 3 study (NCT02896855) also presented at this year’s ASCO meeting, confirmed the benefits of the Perjeta regimen for treating patients with recurrent HER2-positive metastatic breast cancer, with efficacy results consistent with the CLEOPATRA study.
Perjeta, much like Herceptin, is an inhibitor of the HER2 receptor, a protein known to participate in breast cancer growth and survival. But while Perjeta works by preventing the HER2 protein from binding the HER3 protein, Herceptin prevents the HER2 protein from binding to similar HER2 proteins.
Researchers think that blocking both mechanisms could provide more effective inhibition of the HER2 signaling.
Perjeta is approved in the U.S., in combination with Herceptin and chemotherapy, for the treatment of patients with HER2-positive early breast cancer and a high likelihood that the cancer will return after surgery, based on the APHINITY Phase 3 trial (NCT01358877).
It is not yet approved for patients whose cancer came back after surgery and spread to distant organs.