TUESDAY, Dec. 12 (HealthDay News) -- A combination of two drugs -- bortezomib and lenalidomide -- designed to treat the bone marrow cancer multiple myeloma may be more effective together than when the drugs are used individually, a U.S. study concludes.

The phase I clinical trial, led by researchers at the Dana-Farber Cancer Institute in Boston, included 38 patients whose cancer had recurred after previous treatment and continued to progress despite other therapies. The patients were divided into groups that received successively higher doses of bortezomib (brand name Velcade) and lenalidomide (brand name Revlimid).

Some of the patients also received a standard myeloma medication called dexamethasone, which adds to the effects of both bortezomib and lenalidomide.

Of the 36 patients who could be evaluated at the end of the trial, 58 percent had responded to the combined treatment, including six percent who had complete remission. Overall, the average length of remission was six months, but some patients did have disease control for up to 30 months.

Side effects of the combined therapy included mild fatigue and peripheral neuropathy, which is nerve damage characterized by numbness or tingling, the study said.

The findings were to be presented Dec. 11 at the annual meeting of the American Society of Hematology, in Orlando, Fla. The study received funding from Millennium Pharmaceuticals Inc. and Celgene Inc.

"We are hopeful that this combination will prove to be a key therapeutic backbone in improving outcomes for our patients, both early and later in their course," researcher Dr. Paul Richardson said in a prepared statement.