Pertuzumab regimen extends lives in HER2-positive breast cancer

Adding pertuzumab (Perjeta, Roche) to trastuzumab (Herceptin, Genentech) and docetaxel chemotherapy extended the lives (overall survival; OS) of people with previously untreated HER2-positive metastatic breast cancer by 15.7 months compared to Herceptin and chemotherapy (median OS: 56.5 vs. 40.8 months), according to data presented at the European Society for Medical Oncology 2014 congress in Madrid, Spain.

According to the American Cancer Society, metastatic cancer is a cancer that has spread from the part of the body where it started (the primary site) to other parts of the body. When cancer cells break away from a tumor, they can travel to other areas of the body through the bloodstream or the lymph system (which contains a collection of vessels that carry fluid and immune system cells).

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Perjeta targets the HER2 receptor, a protein found on the outside of many normal cells and in high quantities on the outside of cancer cells in HER2-positive cancers. Perjeta is designed specifically to prevent the HER2 receptor from pairing (or “dimerising”) with other HER receptors (EGFR/HER1, HER3 and HER4) on the surface of cells, a process that is believed to play a role in tumour growth and survival. B

“This is extremely important information as it demonstrates greater efficacy with a drug used to treat a very common malignancy,” said according to FormularyWatch advisor James M. Wooten, PharmD, associate professor, department of medicine, University of Missouri-Kansas City School of Medicine. 

“Practitioners will continue to gain knowledge about this drug as more controlled trials are conducted,” Dr Wooten said.

The phase 3 CLEOPATRA (CLinical Evaluation Of Pertuzumab And TRAstuzumab) was an international, randomized, double-blind, placebo-controlled study compared the combination of Perjeta, Herceptin and docetaxel chemotherapy with placebo, Herceptin and chemotherapy in 808 people with previously untreated HER2-positive mBC, or with HER2-positive metastatic breast cancer that had come back after prior therapy in the adjuvant or neoadjuvant setting. The primary end point of the study was progression-free survival (PFS) as assessed by an independent review committee. Secondary end points included OS and safety profile.

The risk of death was reduced by 32% for people who received the Perjeta regimen compared to those who received Herceptin and chemotherapy (HR=0.68, 95% CI, 0.56–0.84; P=.0002). Patients treated with the Perjeta regimen had a 32% reduction in the risk of their disease worsening or death (PFS; HR=0.68, 95% CI, 0.58–0.80) compared to people who received Herceptin and chemotherapy. With longer follow-up, the median PFS improvement of more than 6 months was maintained (median PFS of 18.7 months for people who received Perjeta, Herceptin and chemotherapy compared to 12.4 months for those who received Herceptin and chemotherapy).

Diarrhea, rash, mucosal inflammation, headache, upper respiratory tract infection, itching, low white blood cell count with fever, dry skin and muscle spasms were the most common adverse events seen with the Perjeta regimen.

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