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Lilly Breast Cancer Drug Results May Challenge Pfizer Pill

  • Chances that cancer would progress were reduced by 46%
  • Interim data suggests results similar to Pfizer’s Ibrance

Eli Lilly & Co.’s experimental breast cancer drug abemaciclib, when combined with standard therapy, slowed the progression of the tumor in patients with an advanced form of the disease.

Patients in the late-stage study of 493 women saw the chances that the cancer would progress reduced by 46 percent, according to preliminary results. In the study, 59 percent of patients treated with the drug had their tumors shrink, compared with 44 percent for those taking a placebo with the standard therapy.

The delay in tumor progression is similar to those from trials for Pfizer Inc.’s Ibrance and Novartis AG’s Kisqali, two medicines already approved to treat what is one of the deadliest forms of breast cancer, according to Matt Goetz, co-lead investigator in the Lilly trial.

While the abemaciclib study isn’t complete yet, it already confirms that the class of drugs known as CDK4/6 inhibitors is the most effective therapy for the type of advanced breast cancer studied, said Goetz, a physician at the Mayo Clinic in Rochester, Minnesota. He said abemaciclib provides an option for patients who can’t tolerate the other drugs.

Diarrhea occurred in 81 percent of patients who received abemaciclib, according to the interim data, which was presented at the European Society for Medical Oncology meeting in Madrid.

Additional Option

“We feel very comfortable that this drug will be an interesting addition to the set of options that breast cancer patients have already,” said Levi Garraway, vice president of global oncology at Indianapolis-based Lilly.

Competition may lower the prices of the Pfizer and Novartis treatments, but it’s unlikely to alter the standard of care, said Mariana Chavez Mac Gregor, an oncologist at M.D. Anderson Cancer Center in Houston who treats breast cancer patients.

“It’s not going to be something dramatically different than from what we already have,” Chavez Mac Gregor said.

One difference is in the way the drugs are taken. The Pfizer and Novartis treatments are taken each day for three weeks before abstaining for a week, while abemaciclib is taken every day.

Analysts anticipate the Lilly drug will reach $1.23 billion in sales in 2021, according to predictions compiled by Bloomberg.

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