Updated with new information.

SAN FRANCISCO (TheStreet) -- Scientists and investors are getting their first detailed look this weekend at a large study of Amgen's (AMGN - Get Report) multiple myeloma drug Kyprolis. The study, known as ASPIRE, is a key component of Amgen's strategy to boost Kyprolis sales and not incidentally, justify the high cost to acquire the drug.

Kyprolis is approved in the U.S. as a treatment for multiple myeloma patients no longer responding to any other drugs. But sales generated to date ($240 million in the first three quarters of this year) have been a bit disappointing, lagging, for instance, Celgene's (CELG - Get Report) Pomalyst, which is also approved for a similar myeloma patient population.

Amgen markets Kyprolis following the $10.4 billion acquisition of Onyx Pharmaceuticals. A key assumption in spending that kind of money to buy Onyx was that data from the ASPIRE study and others would secure Kyprolis' approval in Europe and lead to expanded usage in a larger slice of myeloma patients.

The American Society of Hematology is highlighting the Kyprolis ASPIRE study at a press briefing this morning as part of its annual meeting currently underway. Full results from the study are being presented on Sunday afternoon. 

At the ASH media briefing, Dr. Keith Stewart of the Mayo Clinic in Scottsdale, Ariz. and an investigator in the ASPIRE study said the Kyrpolis data should convince myeloma doctors to change the way patients with earlier-stage disease are treated.

The study enrolled 792 patients with multiple myeloma which had relapsed following one to three prior therapies. The patients were randomized to treatment with a combination of Kyprolis, Celgene's Revlimid and a steroid or Revlimid plus the steroid as a control comparator.

At the interim analysis, patients in the Kyprolis arm of the study showed a 31% reduction in the risk that their disease would progress compared to the control arm. At the median, Kyprolis patients reported progression-free survival of 26.3 months compared to a 17.6 months for the control arm. These results satisfied the primary endpoint of the study with statistical significance.

Stewart described the Kyprolis PFS benefit as "unprecedented" for this myeloma patient population.

 

A final analysis of overall survival designed to determine if Kyprolis can help patients live longer has not been completed. An interim survival analysis trended in favor of Kyprolis but the result was not statistically significant.

The ASPIRE study was designed in consultation with regulators in the U.S. and Europe, which gives Amgen confidence that the positive results will be sufficient to win European approval. Some investors and analysts, however, have raised concerns that European regulators might be put off by the lack of a Kyprolis survival benefit. This fear was underscored by the failure of a second, large phase III study of Kyprolis -- dubbed FOCUS -- to also demonstrate a survival benefit in multiple myeloma patients.

Stewart said the survival benefit at the interim analysis trended in favor of Kyprolis and was "encouraging." A final survival analysis will be conducted in the future. "I'm hopeful these data will lead to worldwide regulatory approvals," he added. 

Wall Street sentiment over Kyprolis' future could swing more positive if the drug receives positive feedback from myeloma doctors at this weekend's ASH meeting.

The $240 million in Kyprolis sales reported so far this year come mainly from the U.S. By comparison, Celgene sales of competing myeloma drug Pomalyst have totaled $478 million in the same period, both in the U.S. and in Europe where it's also approved. The comparison between Kyprolis and Pomalyst isn't entirely fair because Celgene has long dominated market share for multiple myeloma drugs with Revlimid, which is on track to generate just under $5 billion in sales this year.

A related trend to watch at this year's ASH meeting is the emergence of new, novel treatments for multiple myeloma. These include the use monoclonal antibodies which bind to proteins known as CD38 found on the surface of myeloma cells. Antibodies such as Roche's (RHHBY) Rituxan are a core treatment in other blood cancers like non-Hodgkin's lymphoma, but this class of drug has never before been developed against myeloma.

Early data on two anti-CD38 antibodies -- daratumumab from a joint venture of Johnson & Johnson ( JNJ) and Genmab  ( GNMSF) and SAR650984 from Sanofi ( SNY - Get Report) -- will be presented at the ASH meeting. Celgene in partnership with Morphosys ( MPSYY) is also developing an anti-CD38 antibody, with significant data expected next year.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.