Test Aids Prostate Cancer Treatment

Print 07 July 2016
Ron Winslow / The Wall Street Journal

Genomic Health will commercialize a new screening to influence choice of therapies

A new blood test can help advanced prostate cancer patients decide whether to try costly new-generation drugs or rely on much cheaper traditional chemotherapy to improve their chances for survival. PHOTO: ACKERMAN + GRUBER FOR THE WALL STREET JOURNAL

Genomic Health Inc. has struck a deal to commercialize a new blood test that can help advanced prostate cancer patients decide whether to try costly new-generation drugs or rely on much cheaper traditional chemotherapy to improve their chances for survival.

The test, developed by closely held Epic Sciences Inc., San Diego, detects a mutation associated with a poor response to two new drugs, Xtandi from Medivation Inc. and Astellas Pharma Inc. of Japan, and Zytiga from Johnson & Johnson.

The two blockbuster drugs have significantly extended survival for many patients with advanced prostate cancer. But in a study published last month, patients who tested positive for the anomaly—a variant of the androgen receptor called AR-V7—lived substantially longer if they were treated with chemotherapy than those given the two new drugs. The receptor is the target of the new drugs.

“If AR-V7 was present, the patients didn’t respond to the [new] agents,” said Howard Scher, chief of genitourinary oncology at Memorial Sloan-Kettering Cancer Center, New York. “They progressed more quickly and they didn’t live as long” as those treated with chemo. Dr. Scher is lead author of the study, which was published online by the journal JAMA Oncology.

The findings suggest that patients with the variant can improve their survival chances while avoiding use of the more-costly therapies. Xtandi is priced at more than $10,000 a month while Zytiga lists at about $8,600. Docetaxel and cabazitaxel, the standard so-called taxane chemotherapies for advanced prostate cancer, cost several hundred dollars a month, researchers said.

“You get both improved clinical outcome and economic benefits to the health system,” said Murali Prahalad, Epic’s president and chief executive.

The retrospective study involved 161 men. Researchers said the test needs further validation in larger, prospective randomized trials. The companies believe the recent study, and previous research linking a poor response to the two drugs to the AR-V7 variant, are sufficient validation for clinical use, said Phil Febbo, Genomic Health’s chief medical officer. They plan to launch the test early next year while more rigorous studies are under way. The price hasn’t been determined.

The companies estimate that about 50,000 U.S. patients a year have advanced prostate cancer that has progressed after standard hormone therapy and would be candidates for the test as they and their doctors consider treatment with the new agents. Studies suggest as many as 20% may have the AR-V7 variant, or acquire it as their tumors change during courses of therapy.

The agreement bolsters Genomic Health’s portfolio of cancer diagnostic tests intended to help doctors tailor treatment based on the molecular traits of their patients’ tumors. Its OncotypeDX line of tests for breast, prostate and colon cancers gives patients with early-stage disease information on whether they’re likely to benefit from chemotherapy—or in the case of the prostate, other aggressive care—as part of their treatment. The new pact is part of Genomic Health’s plan to provide diagnostics to guide treatment for metastatic, or advanced disease.

The test is called a liquid biopsy because it analyzes blood instead of tumor tissue to determine if the mutation is present. It is based on technology that cannot only detect AR-V7 but also determine whether it is in the nucleus of individual tumor cells.

The presence of the AR-V7 in the nucleus is a key factor in whether patients respond to the new drugs, Dr. Scher said. In the study, no patient determined to have the variant in a single tumor cell’s nucleus responded to either Xtandi or Zytiga.

In the study, a positive test for AR-V7 didn’t assure patients would respond to the chemotherapy, nor did a negative test promise a response to the Xtandi or Zytiga.

Under the agreement, which covers commercializing the test in the U.S., Genomic Health is making an equity investment in Epic. Specific financial terms weren’t disclosed.

Qiagen NV of Germany and Tokai Pharmaceuticals Inc., Boston, are codeveloping an AR-V7 liquid biopsy test based on different technology as a diagnostic test for Tokai’s experimental prostate-cancer drug called galeterone intended to treat men who test positive for AR-V7.

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