PRINCETON, N.J. ( TheStreet) -- An experimental immune-based drug developed by Bristol-Myers Squibb (BMY) - Get Report and Abbvie (ABBV) - Get Report added to standard therapy for relapsed multiple myeloma patients reduced the risk of disease progression or death by 30%.

The new Bristol/Abbvie drug is called elotuzumab. Positive results from the phase III study dubbed ELOQUENT-2 were featured in a media preview Wednesday ahead of the American Society of Clinical Oncology (ASCO) annual meeting, which starts May 29.

Bristol is not disclosing regulatory plans for elotuzumab at this time, spokeswoman Audrey Abernathy said. A second phase III study of elotuzumab known as ELOQUENT-1 involving newly diagnosed multiple myeloma patients is still ongoing.

Elotuzumab is a monoclonal antibody designed to target and kill cancer cells in two ways. The drug attaches itself to a protein known as SLAMF7 found only on the surface of myeloma cells. The drug is also believed to activate a type of immune cell known as natural killer cells to target the cancer.

Multiple myeloma is a type of cancer affecting white blood cells. One of the foundational therapies to treat multiple myeloma combines the Celgene (CELG) - Get Report drug Revlimid plus dexamethasone, a chemotherapy.

In the ELOQUENT-2 study, 646 patients with relapsed multiple myeloma were randomized to receive Revlimid-dex (the control group) or Revlimid-dex plus elotuzumab.

At a median follow-up of two years, the patients treated with elotuzumab showed a 30% reduction in the risk of cancer progression and death compared to the control group. At the median, the progression-free survival for elotuzumab-treated patients was 19.4 months compared to 14.9 months for the control group. The benefit favoring elotuzumab was statistically significant, achieving the primary endpoint of the phase III study.

The benefit of Elotuzumab in the study persists for more than three years of follow-up, which suggests the drug is stimulating the patients' immune system to target and kill multiple myeloma cells, said Dr. Sagar Lonial, chief medical officer at the Winship Cancer Institute of Emory University and the principal investigator in the ELOQUENT-2 study.

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The overall response rate for elotuzumab in the study was 79% compared to 66% for the control arm, also statistically significant.

Patients in the study continue to be followed for overall survival.

Mild infusion-related reactions to elotuzumab were recorded in 10% of patients. Other common side effects including neutropenia and anemia occurred equally or more in the control group compared to elotuzumab.

Revlimid is already one the most expensive drugs used to treat multiple myeloma, so adding elotuzumab, if approved, would boost the cost of the combination therapy even higher. Lonial said cost is one factor that must be considered when evaluating the benefit of adding elotuzumab to Revlimid in multiple myeloma, but the price may be justified if the new combination therapy can provide a long-term survival benefit. 

The combination of elotuzumab with Revlimid/dexamethasone was granted Breakthrough Therapy Designation for relapsed multiple myeloma in 2014. The drug is aiming to be the first monoclonal antibody used to treat multiple myeloma. Competition could come from another antibody known as daratumumab under development by Johnson & Johnson (JNJ) - Get Report and Genmab. Results from a phase III study of daratumumab in double refractory multiple myeloma patients will be presented at the ASCO annual meeting.

Bristol is responsible for the majority of clinical development costs of elotuzumab and will sell the drug if approved. Abbvie will receive 30% of profits (or losses) in the U.S. stemming from elotuzumab's sale. Outside the U.S., Bristol will pay Abbvie a royalty based on the drug's sales.

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.