By Bill Berkrot
(Reuters) - Roche's newly approved leukemia drug Gazyva helped patients live nearly a year longer without the disease worsening than the drugmaker's top-selling Rituxan in a head-to-head trial that should help fend off competition from cheaper versions of the older medicine.
Gazyva, previously known as GA101, was approved in the United States last week as an initial treatment for patients with chronic lymphocytic leukemia, or CLL, one of the most common forms of blood cancer. It is awaiting approval decisions in Europe and other markets.
Roche, in the trial, aimed to demonstrate the clear superiority of the new drug over Rituxan in order to protect and build on its $7 billion a year blood cancer franchise before Rituxan begins to face competition from cheaper versions known as biosimilars.
Rituxan's European patent protection expires late this year. It is not clear when the first biosimilar will arrive on the market.
Rituxan's U.S. patent does not expire until 2018, giving Roche additional time to switch patients over to Gazyva in the most lucrative market. As with Rituxan, Roche will share a portion of Gazyva profits with Biogen Idec after Biogen exercised its option on the new drug.
In the 663-patient study, patients who received Gazyva plus the chemotherapy drug chlorambucil on average went 26.7 months without their disease worsening, a measure known as progression free survival, or PFS. That compared with 15.2 months for previously untreated patients who took Rituxan and chlorambucil, according to data announced by the Swiss company on Thursday.
The difference translates into a 61 percent reduction in the risk of the disease worsening.
Three times as many patients who received Gazyva - 21 percent versus 7 percent for Rituxan - had a complete response, meaning no sign of a cancerous tumor after completing treatment.
By another less frequently used measure that tracks cancer cells in the blood following treatment, Gazyva was far superior. By that metric, 29.4 percent of Gazyva patients had no detectable disease in the blood, compared with just 2.5 percent of Rituxan patients.
Gazyva, known chemically as obinutuzumab, is an engineered antibody designed to better enable the immune system to attack and kill B cells, from which many blood cancers, such as CLL and lymphomas, originate. The drug, which recognizes B cells on the surface of tumors, was designed to be more potent in attacking them than Rituxan.
Gazyva plus chemotherapy had previously been tested against chemotherapy alone, demonstrating statistically significant PFS and response superiority. Roche said patients who took Gazyva in that arm of the study lived longer, but it did yet have median overall survival data.
No new safety problems turned up for either Gazyva or Rituxan, Roche said. There was a far higher number of Gazyva patients who suffered adverse infusion-related reactions, such as hives, itching or shortness of breath: 20 percent versus 4 percent for the Rituxan group.
But researchers found no increase in serious infections associated with Gazyva, with infections seen in 7 percent of patients in each group.
It is estimated that more than 15,000 Americans will be diagnosed and nearly 5,000 will die from chronic lymphocytic leukemia in 2013, according to the National Cancer Institute.
Detailed data from the study, dubbed CLL11, will be presented next month at an American Society of Hematology meeting in New Orleans.
(Reporting by Bill Berkrot; Editing by John Wallace)