By Bill Berkrot
Nov 21 (Reuters) - Johnson & Johnson's blockbuster multiple myeloma drug Darzalex when added to a standard therapy regimen reduced the risk of disease progression or death by 50 percent compared with the standard therapy alone in patients not previously treated for the blood cancer, according to data released on Tuesday.
The data could lead to approval of the Darzalex combination as an initial, or first-line, therapy for multiple myeloma, providing a larger sales opportunity for the medicine, one of J&J's most important growth drivers.
Darzalex, a biotech drug known chemically as daratumumab, is already approved in combination with other medicines or alone in patients who had received one or more prior treatment regimens.
It had third quarter sales of $317 million, with annual sales forecast to reach about $5 billion by 2021, according to Thomson Reuters data.
In the first-line study, 706 patients deemed not eligible for bone marrow transplant received either Darzalex with Takeda Pharmaceutical's Velcade, the chemotherapy melphalan and the steroid prednisone or the combination without Darzalex.
Median time until disease progression, or progression-free survival, was 18.1 months for the standard regimen but had not yet been reached for the Darzalex group, according to a summary of data to be presented next month at the American Society of Hematology (ASH) meeting in Atlanta.
The superior PFS with Darzalex was driven by more patients achieving deep responses, including a significantly higher complete response rate, researchers concluded.
The overall response rate was 90.9 percent for the Darzalex group, while 73.9 percent of those in the control group responded.
The rate of complete responses, meaning no detectable cancer in the blood or bone marrow, was 42.6 percent for Darzalex versus 24.4 percent for the standard regimen.
Overall survival data was not yet available.
About 71 percent of Darzalex patients had what was deemed a very good partial response versus 49.7 percent for the other regimen.
There was a higher rate of serious infections in the Darzalex group - 23.1 percent vs 14.7 percent.
Dr. Kenneth Anderson, the ASH president, called the responses "impressive," but added they were likely to be viewed as even more significant outside the United States.
The trial was primarily conducted in Europe using the standard first-line regimen there. Celgene Corp's Revlimid is part of the standard regimen used in the United States.
"It likely will be the basis for approval of daratumumab to be incorporated into the initial combination therapy of myeloma," Anderson said of the results. (Reporting by Bill Berkrot; Editing by Andrew Hay)