AstraZeneca’s Olaparib Prolongs Remission in Ovarian Cancer, Study Finds
AstraZeneca Plc (AZN)’s experimental pill olaparib prolonged remission rates in women with ovarian cancer, slowing progression of the deadly disease, researchers said.
The medication, designed to prevent tumor cells from repairing damage caused naturally or by chemotherapy, helped women with serous ovarian cancer live for 8.4 months before the tumor resumed growing, compared with 4.8 months for those given a placebo. All 264 women were in remission when they started the company-funded study, a time when no drugs are typically taken.
The findings reveal a broader range of patients who may benefit from olaparib, known as a PARP inhibitor, said senior author Ursula Matulonis, medical director of gynecological oncology at Dana-Farber Cancer Institute in Boston. The medicine has mainly been studied in a small group of women with BRCA gene mutations that put them at increased cancer risk, she said. The latest trial wasn’t limited to women with the gene mutation.
“This is expanding the population that may be amenable to therapy with a PARP inhibitor,” Matulonis said in a telephone interview. “We are starting to hone in on where PARP inhibitors may have the most efficacy, so you don’t give a drug to a patient who wouldn’t have a chance at response.”
The excitement surrounding the novel class of medicines dissipated in January when Sanofi’s BSI-201, the lead compound in the category, failed to help patients with a hard-to-treat breast cancer live longer, Michael Leacock, an analyst at Royal Bank of Scotland in London, said in an e-mail. He gives the drug from London-based AstraZeneca a 40 percent chance at success with a first filing for regulatory approval in 2015, and estimates sales of $130 million in 2017.
Medical Meeting
The findings of the study from the second of three stages needed to win regulatory approval will be presented at the American Society of Clinical Oncology meeting, which starts June 3 in Chicago.
AstraZeneca canceled a phase 3 breast cancer trial after a study last October showed olaparib failed to benefit women with BRCA-related ovarian cancer more than chemotherapy and said it was waiting for additional results before moving forward.
Patients in AstraZeneca’s trials have had to take numerous capsules to get the correct dose of olaparib, said Jane Robertson, the company’s medical science director. The company won’t move to the next phase of testing for the drug until it develops a tablet that can hold a higher dose, she said.
The company hopes to have additional data on olaparib in combination with chemotherapy for ovarian cancer and a tablet to take forward by the end of the year, she said in a telephone interview.
Abbott PARP Inhibitor
A separate study showed Abbott Laboratories (ABT)’ ABT-888, a rival PARP inhibitor, may help patients with advanced colon cancer who have no other treatment options. Cancer growth was halted for about six months in 23 percent of the 49 patients given ABT-888 plus Merck & Co.’s Temodar chemotherapy, and two had their tumors shrink.
The study was funded by the Ruesch Center for the Cure of Gastrointestinal Cancers in Washington. Abbott, based in Abbott Park, Illinois, provided the ABT-888 pills free of charge. The class of medicines is called PARP inhibitors because they block the enzyme that helps repair damaged DNA.
“This is a classic one-two punch: the chemotherapy damages the cancer cells and the PARP inhibitor prevents it from fixing itself, leaving the cell to die,” said lead researcher Michael Pishvaian, an assistant professor at Georgetown University Medical Center’s Lombardi Comprehensive Cancer Center.
The researchers are analyzing tissue samples to see if they can discern why the remaining 39 patients didn’t respond, he said in a telephone interview. The findings will help identify patients for future studies that may get the best results.
Ovarian Cancer Potential
More than 21,000 women in the U.S. are diagnosed with ovarian cancer each year, and almost 14,000 die from it, according to the American Cancer Society.
About 60 percent have serous ovarian cancer, a tumor type that often already has problems fixing damaged DNA. Using a PARP inhibitor to block an enzyme needed to carry out such repairs can further accelerate cancer cell death, even when given alone, Robertson said.
“If the cell already has a deficiency in this area, it’s like an Achilles heel where the PARP inhibitor can move in and have a chance at efficacy,” Matulonis said. “It predisposes the tumor cell to respond.”
Once the cancer returns, it’s much less likely to be cured, Robertson said. While patients get treated again, fewer respond and the benefit isn’t as long-lasting. Existing chemotherapy drugs are too toxic for patients to get while in remission, she said.
“This will be embraced because we know the outcome is grim for women with ovarian cancer,” said Karen Lu, professor of gynecologic oncology at MD Anderson Cancer Center in Houston.
The remaining question is whether the drug prolongs overall survival, Lu, who wasn’t involved in the trial, said in a telephone interview. “If we can continue to stretch out survival with a drug that has relatively minimal side effects, that is a gain for us.”
To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net
To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net
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