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MDx/CDx Focus: EMA Okays Perjeta; Published Study on Prolaris; HER2 Tests for Kadcyla Clear FDA


EMA Approves Roche/Genentech's Perjeta

Roche has garnered approval from the European Medicines Agency for its HER2-positive metastatic breast cancer drug Perjeta.

The agency has approved Perjeta in combination with Herceptin and docetaxel for patients with HER2-positive metastatic breast cancer or locally recurrent, unresectable disease who haven't received anti-HER2 treatments or chemotherapy for their advanced stage cancer.

The US Food and Drug Administration approved the drug, along with two new HER2 companion tests last June (PGx Reporter 6/13/2012).

Perjeta, developed by Roche subsidiary Genentech, is a monoclonal antibody that inhibits the HER2 receptor from joining with other HER receptors, such as EGFR/HER1, HER3, and HER4, thereby stopping cancer growth by blocking cell signaling in HER2-positive cancer. Since Perjeta binds to a different region of the HER2 receptor than Herceptin, by combining the two drugs Genentech is hoping to provide a more effective blockade against the HER2 signaling that drives cancer. Herceptin, also developed by Genentech, was the first drug approved for HER2-positive breast cancer.

The European and US regulators approved Perjeta based on data from the 800-patient CLEOPATRA trial. In the study, HER2-positive breast cancer patients were randomized to receive either the Perjeta/Herceptin/docetaxel cocktail or Herceptin/docetaxel plus a placebo. The data, published in the New England Journal of Medicine in December by researchers led by Jose Baselga of Harvard Medical School, showed that patients receiving the Perjeta-containing regimen experienced a median progression-free survival of 18.5 months compared to 12.4 months for those receiving just Herceptin plus chemotherapy. Common side effects linked to the Perjeta regimen included diarrhea, hair loss, reduced white blood cells, nausea, fatigue, rash, and nerve damage.

Myriad Nets Fourth Published Study for Prolaris

The Journal of Clinical Oncology has published a fourth study on Myriad Genetics' Prolaris test, the company announced this week. The study, involving more than 400 men who had undergone a radical prostatectomy, showed that the multi-gene test could accurately assess which study participants were at heightened risk for prostate cancer recurrence.

The study adds to a growing body of evidence supporting the use of Prolaris to gauge which patients are at high or low risk of prostate cancer recurrence.

Prolaris analyzes the expression level of 46 cell cycle progression genes and stratifies men's risk of biochemical recurrence of prostate cancer. In the published study, researchers from the University of California, San Francisco, and Myriad reported that 100 percent of the men whom Prolaris deemed to be at "low risk" of recurrence did not experience a recurrence within the five years the study was ongoing. Meanwhile, 50 percent of those the test deemed to be a "high risk" did experience recurrence during that time.

Additionally, the researchers found that the Prolaris test could "more accurately predict the risk of prostate cancer recurrence than current clinical parameters used in risk assessment."

Currently, after a man receives a prostatectomy, a physician will monitor him until biochemical recurrence has occurred but doesn't provide additional treatment post surgery. However, 30 percent of patients experience recurrence in this setting. Myriad is hoping that with the help of Prolaris, doctors will be able to identify which patients need to be treated aggressively with radiation or chemotherapy after surgery.

Prolaris represents a major revenue opportunity for Myriad and a $1 billion market potential. The company is marketing Prolaris as a test that doctors can use in conjunction with clinical parameters to gauge the aggressiveness of a patients' prostate cancer. After the publication of this latest study in JCO, Myriad said it will have published, peer-reviewed data on Prolaris involving 1,500 patients.

"In all four studies, researchers were able to demonstrate the effectiveness of the Prolaris test as a prognostic tool for predicting the risk of recurrence and prostate cancer survival across a variety of tissue formats," the company said in a statement.

An upcoming competitor to Prolaris may be a test that is slated for launch later this year by Genomic Health. The company has said it has conducted six feasibility and development studies in partnership with the Cleveland Clinic to evaluate more than 700 patients and 700 candidate genes in order to select the multi-gene set for the prostate cancer test.

Upon launching the molecular diagnostic, Genomic Health will market it as a tool that doctors can use in conjunction with the Gleason grading system, the prostate specific antigen test, and patients' other clinical data in order to personalize prostate cancer treatment. That test, according to Genomic Health, can differentiate which patients have aggressive or indolent disease.

Week after Kadcyla Approval, FDA Green Lights Companion Tests Developed by Dako

Agilent subsidiary Dako announced this week that the US Food and Drug Administration has approved two of its tests as companion diagnostics for Kadcyla, a drug for HER2-positive breast cancer.

The agency approved Kadcyla, developed by Genentech, on Feb. 22 (PGx Reporter 2/27/2013). The drug is indicated as a treatment for HER2-positive metastatic breast cancer for patients who have received prior treatment with another HER2-targeted drug Herceptin (trastuzumab) and a taxane chemotherapy. The drug is an antibody-drug conjugate in that it combines Herceptin with the chemotherapy DM1 via a stable linker.

The two assays now approved by FDA are Dako's HercepTest and HER2 IQFISH pharmDx, which physicians can use to gauge whether patients harbor HER2-positive tumors that can benefit from Kadcyla treatment.

According to Dako, the company inked a collaboration with Genentech specifically to advance companion tests for Kadcyla in 2012. Later that same year, Dako submitted applications for its two tests for regulatory approval with the FDA.

The FDA usually aims for simultaneous approval of drug/test combination products, as it did with Herceptin, Pfizer's Xalkori, and Roche's Zelboraf. However, sometimes the approval times for the drug and accompanying tests are slightly off. For example, last year, when FDA approved Genentech's other HER2-targeted, metastatic breast cancer treatment Perjeta for previously untreated patients, the approval of the two HER2 companion tests (also developed by Dako) followed a few days later (PGx Reporter 6/13/2012). This is the same situation with Kadcyla.